Toner particle manufacturing method

Abstract

To provide a method for manufacturing toner particles, capable of manufacturing the toner particles having excellent degree of coloring and charge stability while reducing an environmental load.SOLUTION: There is provided a method for manufacturing toner particles including a colorant, a binder resin and a wax, where the binder resin includes one or more kinds of resins. The method comprises steps of: preparing a toner master batch including at least the colorant, the one or more kinds of resins and the wax; dissolving or dispersing the toner master batch in an organic solvent to prepare an oil phase; adding an aqueous medium to the oil phase to perform phase inversion emulsification and obtain an oil-in-water type dispersion having fine particles dispersed in the oil phase; and adding a flocculant to the oil-in-water type dispersion to flocculate the fine particles. The colorant is C.I.Pigment Yellow 185, and the flocculant is metal salt.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing toner particles.

Background Art

[0002] In recent years, there has been a demand for reducing the environmental impact of toner. As a countermeasure, for example, reduction of energy and chemicals used in the toner manufacturing process has been studied. As such a toner manufacturing method, wet granulation methods such as emulsion polymerization method and suspension polymerization method are known.

[0003] For example, Patent Document 1 discloses a method for manufacturing an electrophotographic toner, which includes a step of obtaining a resin emulsion in which a toner master batch and a binder resin are dispersed and emulsified in an aqueous medium, and a step of aggregating and coalescing the obtained resin emulsion.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in wet granulation methods such as emulsion polymerization method and suspension polymerization method, when a pigment master batch is dissolved in an organic solvent, the effect of the pigment dispersion becomes small, and the pigment is unevenly distributed on the surface of the toner during the tonerization process. As a result, sufficient coloring degree and charge stability may not be obtained.

[0005] One aspect of the present invention is to provide a method for manufacturing toner particles capable of manufacturing toner particles having excellent coloring degree and charge stability while reducing the environmental impact.

Means for Solving the Problems

[0006] One aspect of the present invention is a method for manufacturing toner particles containing a colorant, a binder resin, and a wax, wherein the binder resin includes one or more resins, and a step of preparing a toner master batch containing at least the colorant, one or more of the resins, and the wax, and adding an aqueous medium to the oil phase to perform phase inversion emulsification, and the oil The relationshipThe process involves obtaining a dispersed oil-in-water dispersion, adding an aqueous medium to the oil phase to perform phase inversion emulsification to obtain an oil-in-water dispersion in which the oil phase is dispersed, and removing the solvent from the oil-in-water dispersion to obtain a dispersion in which fine particles are dispersed. Fine particles dispersed The process includes the step of adding a flocculant to a dispersion to flocce the fine particles, wherein the coloring agent is CIPigment Yellow 185 and the flocculant is a metal salt. [Effects of the Invention]

[0007] One aspect of the present invention provides a method for producing toner particles that have excellent coloration and electrostatic stability while reducing environmental impact. [Modes for carrying out the invention]

[0008] The method for producing toner particles according to this embodiment is a method for producing toner particles comprising a colorant, a binder resin, and a wax, wherein the binder resin comprises one or more types of resins, and includes the steps of: preparing a toner masterbatch comprising at least a colorant, one or more types of resins, and a wax; dissolving or dispersing the toner masterbatch in an organic solvent to prepare an oil phase; adding an aqueous medium to the oil phase to perform phase inversion emulsification to obtain an oil-in-water dispersion in which fine particles of the oil phase are dispersed; and adding a flocculant to the oil-in-water dispersion to flocce the fine particles.

[0009] Furthermore, the coloring agent used in the toner particle manufacturing method of this embodiment is CIPigment Yellow 185, and the flocculant is a metal salt.

[0010] With the above configuration, the toner particle manufacturing method of this embodiment makes it possible to produce toner particles with excellent coloration and electrostatic stability while reducing environmental impact.

[0011] <Toner Masterbatch Manufacturing Process> The toner masterbatch manufacturing process involves creating a toner masterbatch containing at least a colorant, one or more types of resin, and wax. The colorant used in this process is CIPigment Yellow 185.

[0012] At least CIPigment Yellow 185 as a coloring agent, one or more resins, and wax are mixed and kneaded under high shear force. The kneading machine used can be a general-purpose machine such as a twin-screw extruder, a three-roll kneader, or a lab blast mill.

[0013] The resin used in the toner masterbatch manufacturing process may be all of the one or more resins contained in the binder resin. If the binder resin contains multiple types of resins, the resin used in the toner masterbatch manufacturing process may be one or two, or some of the resins from among the multiple types.

[0014] Furthermore, internal additives may be added during the mixing process. Heating is preferable during mixing, and the heating conditions can be set as appropriate.

[0015] The toner masterbatch preparation process reduces the shock to the colorant (CIPigment Yellow 185) during oil phase dispersion when the toner masterbatch is dissolved or dispersed in the organic solvent in the subsequent oil phase preparation process, thereby preventing the aggregation of the colorant.

[0016] Therefore, the dispersibility of the colorant can be improved, and toner particles (yellow toner) with excellent coloration can be manufactured. In addition, since the uneven distribution of the colorant on the surface of the toner particles can be suppressed, variations in the resistance value of the resin contained in the toner particles can be suppressed, and toner particles (yellow toner) with excellent electrostatic stability can be manufactured.

[0017] [Coloring agent] The colorant used in the toner particle manufacturing method of this embodiment is CIPigment Yellow 185 (hereinafter referred to as "PY185"), which is an isoindoline pigment. Isoindoline pigments have excellent weather resistance among azo pigments due to their structure.

[0018] Furthermore, PY185 exhibits high transparency as a standalone pigment, displays a vivid yellow color, and has strong coloring power. Because PY185 has high transmittance in the visible range at longer wavelengths of 500-700 nm, it also exhibits good secondary color development. PY185 is a highly safe pigment that does not contain dichlorobenzidine.

[0019] The PY185 content is preferably 1 to 15% by weight relative to the toner, and more preferably 3 to 10% by weight. By having a PY185 content within the range of 1 to 15% by weight relative to the toner, toner particles with superior coloration and electrostatic stability can be produced.

[0020] [Binding resin] The binder resin used in the toner particle manufacturing method of this embodiment may be any polymer that is soluble in organic solvents and insoluble or practically insoluble in water. Examples include polystyrene, styrene-acrylic copolymer, polyvinyl chloride, polyvinyl acetate, polymethacrylate, methyl polyacrylate, polyacrylic acid ester, polyacrylonitrile, epoxy resin, polyethylene, polyurethane, polyester resin, polyethylene terephthalate, polyamide, paraffin wax, etc. These may be used individually or in combination of two or more. Among these, polyester resin is preferred.

[0021] (Polyester resin) Examples of polyester resins include polyester resins having only a polyester skeleton, and block polymers of polyester resin and resins having other skeletons. Among these, polyester resins having only a polyester skeleton are preferred.

[0022] Examples of polyester resins having only a polyester backbone include ring-opening polymers of lactones, polycondensates of hydroxycarboxylic acids, polycondensates of polyols and polycarboxylic acids, and the like. Among these, from the viewpoint of design freedom, polycondensates of polyols and polycarboxylic acids are preferred.

[0023] Examples of the polyester resin also include crystalline polyester resins and amorphous polyester resins, with amorphous polyester resins being more preferred. When the polyester resin is an amorphous polyester resin, the uniformity of the polyester resin in the resulting toner particles can be enhanced.

[0024] The weight average molecular weight of the polyester resin is usually 1,000 to 30,000, preferably 3,000 to 15,000, and more preferably 5,000 to 12,000. If the weight average molecular weight of the polyester resin is less than 1,000, the heat-resistant storage property deteriorates, and if it exceeds 30,000, the low-temperature fixing property deteriorates as an electrostatic latent image developing toner.

[0025] The glass transition temperature of the polyester resin is 35 to 80°C, preferably 40 to 70°C, and more preferably 45 to 65°C.

[0026] If the glass transition temperature of the polyester resin is less than 35°C, the resulting colored resin particles may deform when placed in a high-temperature environment such as midsummer, or the colored resin particles may stick together and lose their original behavior as particles. Also, if the glass transition temperature of the polyester resin exceeds 80°C, the fixing property deteriorates when the colored resin particles are used as an electrostatic latent image developing toner.

[0027] (Amorphous polyester resin) The amorphous polyester resin is not particularly limited and can be appropriately selected according to the purpose.

[0028] Examples of amorphous polyester resins include ring-opening polymers of lactones, condensation polymers of hydroxycarboxylic acids, and polycondensates of polyols and polycarboxylic acids. Among these, polycondensates of polyols and polycarboxylic acids are preferred from the viewpoint of design flexibility.

[0029] In this embodiment, amorphous polyester resin refers to a resin obtained by reacting a polyol with a polycarboxylic acid, as described above. Modified polyester resins, such as prepolymers and modified polyester resins obtained by at least crosslinking or stretching the prepolymer, are not included in amorphous polyester resins in this embodiment and are treated as modified polyester resins.

[0030] Furthermore, amorphous polyester resin is a polyester resin component that is soluble in tetrahydrofuran (THF).

[0031] (Crystalline polyester resin) There are no particular restrictions on the crystalline polyester resin, and it can be appropriately selected depending on the purpose. For example, a crystalline polyester resin obtained by reacting a polyol with a polycarboxylic acid can be used.

[0032] In this embodiment, crystalline polyester resin refers to a resin obtained by reacting a polyol with a polycarboxylic acid, as described above. Modified polyester resins, such as prepolymers, and resins obtained by at least crosslinking or stretching the prepolymer, do not belong to the category of crystalline polyester resins.

[0033] The crystalline polyester resin is preferably composed of a linear saturated aliphatic dicarboxylic acid having 4 to 12 carbon atoms and a linear saturated aliphatic diol having 2 to 12 carbon atoms. This results in high crystallinity and excellent sharp melt properties, enabling superior low-temperature fixation.

[0034] Furthermore, methods for controlling the crystallinity and softening point of crystalline polyester resins include designing and using nonlinear polyesters produced by condensation polymerization by adding trivalent or higher polyhydric alcohols such as glycerin to the alcohol component, or trivalent or higher polycarboxylic acids such as trimellitic anhydride to the acid component.

[0035] The molecular structure of crystalline polyester resins can be confirmed by NMR measurements in solution and solid state, as well as by X-ray diffraction, GC / MS, LC / MS, and IR measurements. However, a simpler method is to detect crystalline polyester resins in infrared absorption spectra that exhibit absorption based on δCH (out-of-plane bending vibration) of olefins at 965±10 cm⁻¹ or 990±10 cm⁻¹.

[0036] Regarding the molecular weight of crystalline polyester resins, those with a sharp molecular weight distribution and low molecular weight exhibit excellent low-temperature fixation, while those with a high proportion of low molecular weight components have poor heat-resistant storage properties. Therefore, it is preferable that the molecular weight distribution of the soluble components of o-dichlorobenzene, obtained by gel permeation chromatography (GPC), shows a molecular weight distribution graph with log(M) on the x-axis and weight% on the y-axis, with the peak position in the range of 3.5 to 4.0, the full width at half maximum of the peak being 1.5 or less, a weight-average molecular weight (Mw) of 3,000 to 30,000, a number-average molecular weight (Mn) of 1,000 to 10,000, and an Mw / Mn ratio of 1 to 10.

[0037] Furthermore, it is more preferable that the weight-average molecular weight (Mw) is 5,000 to 15,000, the number-average molecular weight (Mn) is 2,000 to 10,000, and the Mw / Mn ratio is 1 to 5.

[0038] There are no particular restrictions on the acid value of the crystalline polyester resin, and it can be appropriately selected depending on the purpose. However, from the viewpoint of affinity between paper and resin, a value of 5 mg KOH / g or higher is preferred, and 70 mg KOH / g or higher is more preferred, in order to achieve the desired low-temperature fixation. On the other hand, to improve resistance to high-temperature offset, a value of 45 mg KOH / g or lower is preferred.

[0039] There are no particular restrictions on the hydroxyl value of the crystalline polyester resin, and it can be appropriately selected depending on the purpose. In order to achieve the desired low-temperature fixability and good electrostatic properties, the hydroxyl value of the crystalline polyester resin is preferably 0 mg KOH / g to 50 mg KOH / g, and more preferably 5 mg KOH / g to 50 mg KOH / g.

[0040] There are no particular restrictions on the melting point of the crystalline polyester resin, and it can be appropriately selected depending on the purpose, but 60°C to 80°C is preferred. If the melting point is 60°C or higher, the crystalline polyester resin melts easily at low temperatures, which prevents the problem of reduced heat resistance storage of the toner. If the melting point is 80°C or lower, the crystalline polyester resin does not melt sufficiently due to heating during fixing, which prevents the problem of reduced low-temperature fixing performance.

[0041] There are no particular restrictions on the content of crystalline polyester resin, and it can be appropriately selected depending on the purpose, but it is preferably 4% to 30% by mass, and more preferably 5% to 25% by mass, relative to the total amount of toner. If the content is 4% by mass or more, it is possible to prevent the problem of poor low-temperature fixation due to insufficient sharp melt formation by the crystalline polyester resin. If the content is 30% by mass or less, it is possible to prevent the problem of deterioration of cohesiveness and adhesion at high temperatures.

[0042] -Polyol- There are no particular restrictions on the polyol used in polyester resins, and they can be appropriately selected depending on the purpose. Examples include diols and polyols with a valent or higher hydration. These may be used individually or in combination of two or more, but diols alone or a mixture of a diol and a small amount of polyol with a valent or higher hydration are preferred.

[0043] Examples of diols include alkylene glycols, alkylene ether glycols, bisphenols, alicyclic diols, alkylene oxide adducts of alicyclic diols, 4,4'-dihydroxybiphenyls, bis(hydroxyphenyl)alkanes, bis(4-hydroxyphenyl) ethers, and alkylene oxide adducts of bisphenols.

[0044] Examples of alkylene glycols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol.

[0045] Examples of alkylene ether glycols include diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol.

[0046] Examples of bisphenols include bisphenol A, bisphenol F, and bisphenol S.

[0047] Examples of alicyclic diols include 1,4-cyclohexanedimethanol and hydrogenated bisphenol A.

[0048] Examples of 4,4'-dihydroxybiphenyls include 3,3'-difluoro-4,4'-dihydroxybiphenyl.

[0049] Examples of bis(hydroxyphenyl)alkanes include bis(3-fluoro-4-hydroxyphenyl)methane, 1-phenyl-1,1-bis(3-fluoro-4-hydroxyphenyl)ethane, 2,2-bis(3-fluoro-4-hydroxyphenyl)propane, 2,2-bis(3,5-difluoro-4-hydroxyphenyl)propane (also known as tetrafluorobisphenol A), and 2,2-bis(3-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane.

[0050] Examples of bis(4-hydroxyphenyl) ethers include bis(3-fluoro-4-hydroxyphenyl) ether.

[0051] Examples of alkylene oxides in alkylene oxide adducts of alicyclic diols or alkylene oxide adducts of bisphenols include ethylene oxide, propylene oxide, and butylene oxide.

[0052] Among these, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are preferred, and alkylene oxide adducts of bisphenols, and combinations thereof with alkylene glycols having 2 to 12 carbon atoms are more preferred.

[0053] Examples of alcohols with a valency of 3 or higher include polyhydric aliphatic alcohols with a valency of 3 or higher, phenols with a valency of 3 or higher, and alkylene oxide adducts of phenols with a valency of 3 or higher.

[0054] Examples of polyhydric aliphatic alcohols with a valency of 3 or higher include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol.

[0055] Examples of phenols with a valency of 3 or higher include trisphenol PA, phenol novolac, and cresol novolac.

[0056] -Polycarboxylic acid- There are no particular restrictions on the polycarboxylic acid, and it can be appropriately selected depending on the purpose. Examples include dicarboxylic acids and polycarboxylic acids with a valency of three or more. These may be used individually or in combination of two or more, but dicarboxylic acids alone or a mixture of dicarboxylic acids and a small amount of polycarboxylic acid with a valency of three or more are preferred.

[0057] Examples of dicarboxylic acids include alkylenedicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylenedicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc.); 3-fluoroisophthalic acid, 2-fluoroisophthalic acid, 2-fluoroterephthalic acid, 2,4,5,6-tetrafluoroisophthalic acid, 2,3,5,6-tetrafluoroterephthalic acid, 5-trifluoromethyl Examples include isophthalic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane, 2,2-bis(3-carboxyphenyl)hexafluoropropane, 2,2'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 3,3'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 2,2'-bis(trifluoromethyl)-3,3'-biphenyldicarboxylic acid, and hexafluoroisopropylidene diphthalic anhydride.

[0058] Among these, alkenylenedicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms are preferred.

[0059] Examples of polycarboxylic acids with a valency of 3 or more include aromatic polycarboxylic acids with 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid).

[0060] Furthermore, as the polycarboxylic acid, the acid anhydride of the polycarboxylic acid described above, or a lower alkyl ester (methyl ester, ethyl ester, isopropyl ester, etc.) may be used.

[0061] The ratio of polyol to polycarboxylic acid is preferably 2 / 1 to 1 / 2, more preferably 1.5 / 1 to 1 / 1.5, and even more preferably 1.3 / 1 to 1 / 1.3, based on the equivalent ratio of hydroxyl group [-OH] to carboxyl group [-COOH] [-OH] / [-COOH].

[0062] (Modified polyester resin) Modified polyester resins are obtained by at least crosslinking or stretching a prepolymer, and examples include reaction products of a prepolymer and an active hydrogen group-containing compound.

[0063] Modified polyester resin is a polyester resin that is insoluble in tetrahydrofuran (THF). Polyester resin components that are insoluble in tetrahydrofuran (THF) have a reduced Tg and melt viscosity, ensuring low-temperature fixability, while having a branched structure in the molecular backbone and a three-dimensional network structure of molecular chains, resulting in rubber-like properties where it deforms at low temperatures but does not flow.

[0064] Modified polyester resins contain active hydrogen group-containing compounds and sites that can react with active hydrogen group-containing compounds. These sites exhibit pseudo-crosslinking behavior, which enhances the rubber-like properties of the prepolymer, making it possible to produce toners with excellent heat resistance, storage resistance, and high-temperature offset resistance.

[0065] By including polyester resin in the binder resin, the crosslinking density with the binder resin can be ensured, improving the dispersibility of the colorant and enabling the production of toner particles with excellent coloration. Furthermore, since the uneven distribution of the colorant on the surface of the toner particles can be suppressed, variations in the resistance value of the resin inherent in the toner particles can be reduced, enabling the production of toner particles with excellent electrostatic stability.

[0066] The dispersibility of colorants encapsulated in toner depends on the viscosity of the binder resin. In the process of adding a flocculant to an oil-in-water dispersion to flocce fine particles, the viscosity of the binder resin is proportional to the ratio of metal salts to carboxyl groups in the polyester resin, if the binder resin is polyester resin. A higher ratio of metal salts to carboxyl groups increases the viscosity (viscoelasticity) of the binder resin, and thus increases the dispersibility of the pigment. This is thought to be because carboxyl groups chelate with metal ions to form metal crosslinks, increasing the crosslink density.

[0067] Furthermore, the use of polyester resin as the binder resin provides excellent fixation. In particular, when used as a toner for electrostatic latent image development in electrophotography, the use of polyester resin provides excellent fixation.

[0068] Furthermore, the binder resin used in the toner particle manufacturing method of this embodiment preferably includes a prepolymer and a resin obtained by at least crosslinking or stretching the prepolymer.

[0069] (Prepolymer) The prepolymer is preferably a polyester resin having a group that can react with an active hydrogen group-containing compound. The prepolymer is not particularly limited and can be appropriately selected depending on the purpose.

[0070] There are no particular restrictions on the active hydrogen group, and it can be appropriately selected depending on the purpose. Examples include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, and mercapto groups. These may be used individually or in combination of two or more.

[0071] Examples of groups that can react with active hydrogen groups include isocyanate groups, epoxy groups, carboxylic acids, and acid chloride groups. Among these, isocyanate groups are preferred because they can introduce urethane or urea bonds into amorphous polyester resins. Since urea bonds are polar groups, they readily adsorb to pigments, enabling high-level dispersion of pigments.

[0072] There are no particular restrictions on the polyester resin containing isocyanate groups, and it can be appropriately selected depending on the purpose. Examples include reaction products of a polyester resin having active hydrogen groups and polyisocyanate.

[0073] Polyester resins having active hydrogen groups can be obtained, for example, by polycondensation of a diol, a dicarboxylic acid, and at least one of a trivalent or higher polyol and a trivalent or higher carboxylic acid. The trivalent or higher polyol and the trivalent or higher carboxylic acid impart a branched structure to the polyester resin containing isocyanate groups.

[0074] The prepolymer may have a branched structure conferred by at least one of a trivalent or higher polyol and a trivalent or higher carboxylic acid.

[0075] The binder resin used in the toner particle manufacturing method of this embodiment includes a prepolymer and a resin obtained by at least crosslinking or stretching the prepolymer, thereby improving the dispersibility of the colorant and enabling the production of toner particles with superior coloration.

[0076] Furthermore, since the uneven distribution of colorants on the toner particle surface can be further suppressed, variations in the resistance value of the resin inherent in the toner particles can be further suppressed, making it possible to manufacture toner particles (yellow toner) with superior electrostatic stability.

[0077] -Polyol- There are no particular restrictions on the polyol used as a prepolymer; it can be appropriately selected depending on the purpose. Examples include diols and polyols with a valent or higher valentity. These may be used individually or in combination of two or more.

[0078] Examples of diols include aliphatic diols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-dodecanediol; diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethyl Examples include diols having oxyalkylene groups such as ethylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A; alicyclic diols to which alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide have been added; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; and alkylene oxide adducts of bisphenols to which alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide have been added. These may be used individually or in combination of two or more.

[0079] Among these, from the viewpoint of controlling the glass transition temperature of the prepolymer to 20°C or below, aliphatic diols having 3 to 10 carbon atoms such as 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol; alkylene oxide adducts of bisphenols such as 2-mol ethylene oxide adducts of bisphenol A are preferred. It is more preferable that the prepolymer uses 50 mol% or more of the alcohol component in the resin.

[0080] The prepolymer is preferably an amorphous polyester resin. By introducing steric hindrance to the resin chain of the prepolymer, the melt viscosity during fixing is reduced, and low-temperature fixing properties are more easily achieved. For this reason, the main chain of the aliphatic diol preferably has a structure represented by the following general formula (1).

[0081] [ka] However, in the general formula (1) above, R1 and R2 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, n represents an odd number from 3 to 9, and in the n repeating units, R1 and R2 may be the same or different.

[0082] Here, the main chain of an aliphatic diol refers to the carbon chain connecting the two hydroxyl groups of the aliphatic diol in the shortest possible number of carbon atoms. When the number of carbon atoms in the main chain is odd, it is preferable because the crystallinity decreases due to the oddness. Furthermore, when there is at least one alkyl group with 1 to 3 carbon atoms in the side chain, it is more preferable because the interaction energy between the main chain molecules decreases due to the stericity.

[0083] Examples of polyols with a valency of 3 or higher include trivalent or higher aliphatic alcohols such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol; trivalent or higher polyphenols such as trisphenol PA, phenol novolac, and cresol novolac; and alkylene oxide adducts of trivalent or higher polyphenols, such as those obtained by adding alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to trivalent or higher polyphenols.

[0084] -Polycarboxylic acid- There are no particular restrictions on the polycarboxylic acid used in the prepolymer, and it can be appropriately selected depending on the purpose. Examples include dicarboxylic acids and polycarboxylic acids with a valent or higher hydration. These may be used individually or in combination of two or more, but dicarboxylic acids alone or a mixture of dicarboxylic acids and a small amount of polycarboxylic acid with a valent or higher hydration are preferred.

[0085] Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, dodecanediic acid, maleic acid, and fumaric acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid; and their anhydrides, lower (1-3 carbon atoms) alkyl esters, and halides. These may be used individually or in combination of two or more.

[0086] Among these, from the viewpoint of controlling the Tg of the prepolymer to 20°C or below, aliphatic dicarboxylic acids with 4 to 12 carbon atoms are preferred, and it is more preferable to use 50% by mass or more of the carboxylic acid component in the resin.

[0087] Examples of trivalent or higher carboxylic acids include trivalent or higher aromatic carboxylic acids; their anhydrides, lower (1-3 carbon atoms) alkyl esters, and halides. Among these, trivalent or higher aromatic carboxylic acids with 9 to 20 carbon atoms, such as trimellitic acid and pyromellitic acid, are preferred.

[0088] Examples of polyisocyanates include diisocyanates and isocyanates with a valency of three or higher.

[0089] There are no particular restrictions on the polyisocyanates, and they can be appropriately selected depending on the purpose. Examples include 1,3- and / or 1,4-phenylenediisocyanate, 2,4- and / or 2,6-tolylenediisocyanate (TDI), crude TDI, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), crude MDI, crude diaminophenylmethane, condensation products of formaldehyde and aromatic amines (aniline) or mixtures thereof; aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aromatic aliphatic diisocyanates, polyisocyanurates with a valency of 3 or higher; and modified products of these isocyanates. These may be used individually or in combination of two or more.

[0090] Examples of aliphatic diisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

[0091] Examples of alicyclic diisocyanates include isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanatoethyl)-4-cyclohexene-1,2-dicarboxylate, and 2,5- and 2,6-norbornane diisocyanate.

[0092] Examples of aromatic diisocyanates include phosgenates of a mixture of diaminodiphenylmethane and a small amount (e.g., 5-20% by mass) of a trifunctional or more polyamine: polyallyl polyisocyanate (PAPI), 1,5-naphthylene diisocyanate, 4,4',4"-triphenylmethane triisocyanate, and m- and p-isocyanatophenylsulfonyl isocyanates.

[0093] Examples of aromatic aliphatic diisocyanates include m- and p-xylylene diisocyanates (XDI) and α,α,α',α'-tetramethylxylylene diisocyanate (TMXDI).

[0094] Examples of polyisocyanurates with a valency of 3 or higher include lysine triisocyanate and diisocyanate-modified alcohols with a valency of 3 or higher.

[0095] Examples of modified isocyanates include those containing urethane groups, carbodiimide groups, allophanate groups, urea groups, biuret groups, uretodione groups, uretoimine groups, isocyanurate groups, and oxazolidone groups.

[0096] [wax] There are no particular restrictions on the wax (release agent), and it can be appropriately selected from known types, such as natural waxes and synthetic waxes. These may be used individually or in combination of two or more types.

[0097] Examples of natural waxes include plant-based waxes such as carnauba wax, cotton wax, and wood wax; animal-based waxes such as beeswax and lanolin; mineral-based waxes such as ozokerite and cerucine; and petroleum-based waxes such as paraffin, microcrystalline, and petrolatum.

[0098] Examples of synthetic waxes include synthetic hydrocarbon waxes such as Fischer-Tropsch wax, polyethylene, and polypropylene; fatty acid amide compounds such as esters, ketones, ethers, 12-hydroxystearic acid amide, stearic acid amide, phthalimide anhydride, and chlorinated hydrocarbons; homopolymers or copolymers of polyacrylates such as poly-n-stearyl methacrylate and poly-n-lauryl methacrylate, which are low molecular weight crystalline polymer resins (for example, copolymers of n-stearyl acrylate and ethyl methacrylate); and crystalline polymers having long alkyl groups in their side chains.

[0099] Among these, hydrocarbon waxes such as paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, and polypropylene wax are preferred.

[0100] There are no particular restrictions on the melting point of the wax, and it can be appropriately selected depending on the purpose, but 50°C to 120°C is preferred, and 60°C to 90°C is more preferred. If the melting point is 50°C or higher, it is possible to prevent the wax from adversely affecting its heat resistance during storage, and if it is 120°C or lower, it is possible to effectively prevent the problem of cold offset occurring during fixing at low temperatures.

[0101] The low-melting-point wax, ranging from 50°C to 120°C, when dispersed with crystalline polyester resin, effectively acts as a release agent between the fixing roller and the toner interface, resulting in good hot offset properties even in an oil-free (no oil-like release agent is applied to the fixing roller) environment.

[0102] The melt viscosity of the wax is preferably 5 cps to 1,000 cps, and more preferably 10 cps to 100 cps, measured at a temperature 20°C higher than the melting point of the wax. If the melt viscosity is 5 cps or higher, a decrease in release properties can be prevented, and if it is 1,000 cps or lower, the effects of hot offset resistance and low-temperature fixing can be fully exhibited.

[0103] There are no particular restrictions on the wax content, and it can be selected appropriately depending on the purpose, but a content of 0% to 40% by mass relative to the total amount of toner is preferable, and 3% to 30% by mass is more preferable. If the content is 40% by mass or less, deterioration of the toner's fluidity can be prevented.

[0104] <Oil phase preparation process> The oil phase preparation process involves dissolving or dispersing a toner masterbatch in an organic solvent to prepare an oil phase in which at least PY185, one or more resins, and waxes are dissolved or dispersed in the organic solvent. In the oil phase preparation process, the materials dissolved or dispersed in the organic solvent include at least the toner masterbatch, and may also include other materials as needed, such as a charge control agent and one or more resins contained in the binder resin.

[0105] When PY185 is used as a pigment alone, it tends to aggregate. However, in this embodiment, by including a toner masterbatch preparation process and an oil phase preparation process, the dispersibility of PY185 can be further improved, and toner particles with excellent coloration can be produced.

[0106] In the oil phase preparation process, one or more resins dissolved or dispersed in the organic solvent can be the same resins as the binder resin described above, such as polyester resins and prepolymers. In the oil phase preparation process, it is preferable to dissolve or disperse the prepolymer and a resin obtained by at least a crosslinking or extension reaction of the prepolymer in the organic solvent, in addition to the toner masterbatch.

[0107] This improves the dispersibility of the colorant, enabling the production of toner particles with excellent coloration. Furthermore, it suppresses the uneven distribution of the colorant on the surface of the toner particles, thereby reducing variations in the resistance value of the resin inherent in the toner particles, and enabling the production of toner particles with excellent electrostatic stability.

[0108] There are no particular restrictions on the method for dissolving or dispersing the toner masterbatch in an organic solvent, and a known method can be appropriately selected depending on the purpose. For example, it can be dissolved or dispersed using a disperser such as a disc mill, homomixer, or bead mill. For example, if using a homomixer, it is preferable to stir at 0°C to 30°C, 6,000 rpm to 12,000 rpm for 30 to 120 minutes.

[0109] (organic solvent) As an organic solvent, it is preferable that it is volatile with a boiling point of less than 100°C, as this facilitates subsequent solvent removal. Examples of such organic solvents include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone (hereinafter sometimes abbreviated as "MEK"), methyl isobutyl ketone, methanol, ethanol, and isopropyl alcohol. These may be used individually or in combination of two or more.

[0110] Among these, when the resin to be dissolved or dispersed in an organic solvent is a polyester resin, ester-based solvents such as methyl acetate, ethyl acetate, and butyl acetate, or ketone-based solvents such as methyl ethyl ketone and methyl isobutyl ketone are preferred in terms of high solubility, and methyl acetate, ethyl acetate, and methyl ethyl ketone are more preferred in terms of high solvent removal.

[0111] <Phase inversion emulsification process> The phase inversion emulsification process involves adding an aqueous medium to the oil phase obtained in the oil phase preparation process to perform phase inversion emulsification, thereby obtaining an oil-in-water dispersion in which fine particles of the oil phase are dispersed. This process transforms the oil phase, which is a water-in-oil solution or dispersion, into an oil-in-water dispersion.

[0112] Furthermore, in order to dissociate the carboxyl groups in the resin and improve the dispersibility of the resin, it is preferable to add an alkaline aqueous medium such as an aqueous ammonia solution to the oil phase to neutralize it to a neutralization rate of 100% to 700%, and then add an aqueous medium such as water to perform phase inversion emulsification to obtain an oil-in-water dispersion.

[0113] The phase inversion emulsification process allows for the production of an oil-in-water dispersion in which fine particles containing at least the materials included in the toner masterbatch, namely PY185, one or more resins, and waxes, are dispersed in an aqueous medium.

[0114] The aqueous medium is not particularly limited as long as phase inversion emulsification occurs, and can be appropriately selected depending on the purpose. Examples include water, a solvent miscible with water, and mixtures thereof. These may be used individually or in combination of two or more. Among these, water is preferred.

[0115] As for solvents miscible with water, there are no particular restrictions as long as phase inversion emulsification occurs, and they can be appropriately selected depending on the purpose. Examples include alcohols, dimethylformamide, tetrahydrofuran, cellosolves, and lower ketones. Examples of alcohols include methanol, isopropanol, and ethylene glycol. Examples of lower ketones include acetone and methyl ethyl ketone.

[0116] The amount of aqueous medium to be added is not particularly limited as long as phase inversion emulsification occurs, and can be appropriately selected according to the purpose, but 150 to 300 parts by mass per 100 parts by mass of oil phase is preferred.

[0117] The phase inversion emulsification of the oil phase from a water-in-oil solution or dispersion to an oil-in-water dispersion can be confirmed by observation with an optical microscope.

[0118] <Desolvent removal process> The desolvation step is a step to remove the organic solvent from the oil-in-water dispersion. There are no particular restrictions on the method of removing the organic solvent from the oil-in-water dispersion, and a known desolvation method can be appropriately selected depending on the purpose.

[0119] For example, methods include gradually increasing the temperature of the oil-in-water dispersion while stirring the entire liquid to completely evaporate and remove the organic solvent from the fine particles (droplets) made of toner material; spraying a dispersion containing fine particles of toner material into a dry atmosphere while stirring to completely remove the organic solvent from the droplets; and reducing the pressure while stirring a dispersion containing fine particles of toner material to evaporate and remove the organic solvent. The latter two methods can also be used in combination with the first method.

[0120] Examples of dry atmospheres in which fine particles made of toner material are sprayed include air, nitrogen, carbon dioxide, and gases such as combustion gases that have been heated. Among these, various gaseous streams heated to a temperature above the boiling point of the organic solvent that exhibits the highest boiling point among those used are preferred.

[0121] Examples of drying methods include spray dryers, belt dryers, and rotary kilns. A dispersion of fine particles of sufficient quality can be obtained through a short drying time.

[0122] <Agglomeration process> The flocculation process involves adding a flocculant to an oil-in-water dispersion to cause the fine particles to flocce. The flocculant is a metal salt.

[0123] The aggregation process preferably involves heating and stirring the fine particles in the oil-in-water dispersion to cause aggregation. This allows for the production of toner particles (aggregated particles) by aggregating the fine particles until they reach a desired particle size.

[0124] There are no particular restrictions on the method of agglomerating fine particles, and any known method can be appropriately selected depending on the purpose. Examples include adding a flocculant or adjusting the pH. When adding a flocculant, it may be added directly, but it is preferable to add an aqueous solution of the flocculant to avoid localized high concentrations. Furthermore, it is preferable to add the flocculant gradually while observing the particle size of the fine particles.

[0125] In the coagulation process, the temperature of the oil-in-water dispersion is preferably between (Tg-10°C) and (Tg+10°C), and more preferably between (Tg-5°C) and (Tg+5°C), relative to the Tg of the resin such as polyester resin. If the temperature is too low, coagulation will not proceed well, resulting in poor efficiency, and if the temperature is too high, the coagulation rate will be too fast, leading to a deterioration of the particle size distribution, such as the generation of coarse particles.

[0126] Once the desired particle size is reached, aggregation is stopped. Methods for stopping aggregation include, for example, adding a salt or chelating agent with a low ionic charge, adjusting the pH, lowering the temperature of the dispersion, or diluting the concentration by adding a large amount of aqueous medium.

[0127] In the aggregation process, wax may be added as a release agent, or crystalline polyester resin may be added for low-temperature fixation. In this case, a dispersion of wax in an aqueous medium, or a dispersion of crystalline polyester resin, can be prepared and mixed with an oil-in-water dispersion containing fine particles made of toner material, and then aggregated. This process allows for the production of aggregated particles in which wax or crystalline polyester resin is uniformly dispersed on the surface of the fine particles.

[0128] As the crystalline polyester resin, the same material as the crystalline polyester resin described above can be used.

[0129] (Flocculant) The flocculant can be any salt of a metal with a valency of 1 or higher, preferably a salt of a metal with a valency of 2 or higher, and more preferably a salt of a metal with a valency of 3 or higher.

[0130] The dispersibility of the colorant can be controlled by the type of metal salt used as a flocculant added in the flocculation process and the method of introducing the colorant. The dispersibility of the colorant encapsulated in the toner depends on the viscosity of the binder resin. The viscosity of the binder resin is proportional to the ratio of metal salts to carboxyl groups in the polyester resin when the binder resin contained in the fine particles in the oil-in-water dispersion obtained in the phase inversion emulsion process is polyester resin.

[0131] A higher ratio of metal salt to carboxyl groups increases the viscosity (viscoelasticity) of the binder resin, thereby increasing the dispersibility of the pigment. This is thought to be because the carboxyl groups chelate with metal ions, forming metal crosslinks and increasing the crosslink density.

[0132] By including a monovalent or higher metal salt in the flocculant, sufficient crosslinking density with the binder resin can be ensured, improving the dispersibility of the colorant and enabling the production of toner particles with excellent coloration. Furthermore, since the uneven distribution of the colorant on the surface of the toner particles can be suppressed, variations in the resistance value of the resin inherent in the toner particles can be reduced, enabling the production of toner particles with excellent electrostatic stability.

[0133] By using a metal salt with a valency of 2 or higher as the flocculant, the crosslinking density with the binder resin can be further ensured, the dispersibility of the colorant can be further improved, and toner particles with superior coloration can be produced.

[0134] Furthermore, since the uneven distribution of colorants on the surface of toner particles can be further suppressed, variations in the resistance values ​​of the resins inherent in the toner particles can be further reduced, making it possible to manufacture toner particles with superior electrostatic stability.

[0135] As metal salts, known metal salts can be used, such as metal salts of monovalent metals like sodium and potassium, metal salts of divalent metals like calcium and magnesium, and metal salts of trivalent metals like iron and aluminum.

[0136] Other processes include, for example, the aforementioned solvent removal process, fusion process, washing and drying process, annealing process, and external additive process.

[0137] <Fusing process> The fusion process involves fusing the aggregated particles obtained in the aggregation process by heat treatment, and it is preferable to heat the dispersion of aggregated particles while stirring. This makes it possible to obtain fused particles with reduced surface irregularities.

[0138] When heat-treating the aggregated particles, a temperature near the temperature exceeding the Tg of the binder resin (above Tg and below Tg + 15°C) is preferred.

[0139] There are no particular restrictions on the average circularity of the fused particles, and they can be appropriately selected depending on the purpose, but 0.940 to 0.985 is preferred, and 0.950 to 0.975 is more preferred.

[0140] <Washing and drying process> The washing and drying process involves washing and drying the aggregated particles obtained in the aggregation process or the fused particles obtained in the fusion process to obtain toner particles.

[0141] Since the dispersion of fused particles obtained in the fusion process contains by-products such as agglutinating salts in addition to fine particles made of toner material, it is preferable to wash and dry the dispersion in order to separate only the toner particles.

[0142] There are no particular restrictions on the washing method, and it can be appropriately selected depending on the purpose. Examples include centrifugal separation, vacuum filtration, and filter pressing. A cake of toner particles can be obtained by any of these methods, but if the washing is not sufficient in a single operation, the obtained cake may be dispersed again in an aqueous solvent to form a slurry, and the process of extracting the toner particles using one of the above methods may be repeated.

[0143] When washing is performed by vacuum filtration or filter press, a method may be used in which an aqueous solvent is passed through the cake to wash away auxiliary materials contained in the toner particles.

[0144] Examples of aqueous solvents used for washing include water or mixed solvents obtained by mixing water with alcohols such as methanol or ethanol. Of these, water is preferred considering the cost and environmental impact due to wastewater treatment.

[0145] Since the toner particles obtained through washing contain a large amount of water-based media, drying them to remove the water-based media will allow you to obtain only the toner particles.

[0146] There are no particular restrictions on the drying method, and it can be appropriately selected depending on the purpose. Examples of drying methods include using a spray dryer, vacuum freeze dryer, reduced pressure dryer, stationary shelf dryer, mobile shelf dryer, fluidized bed dryer, rotary dryer, and agitated dryer.

[0147] Drying is preferably carried out until the moisture content in the dried toner particles is ultimately less than 1%.

[0148] Furthermore, if the toner particles are softly aggregated after drying, causing problems during use, the aggregated particles may be broken up using equipment such as a jet mill, Henschel mixer, super mixer, coffee mill, Auster blender, or food processor.

[0149] <Annealing Process> The annealing process is performed after the drying process when crystalline polyester resin is added during the aggregation process. It is preferable to store the toner particles at a temperature near the glass transition temperature (Tg) of the polyester resin for 10 hours or more. This causes phase separation between the amorphous polyester resin and the crystalline polyester resin when an amorphous polyester resin is used as the binder resin, improving the fixation properties.

[0150] The preferred temperature range for the glass transition temperature (Tg) of polyester resin is (Tg-15°C) to (Tg+5°C).

[0151] <External addition process> The external additive process involves adding and mixing external additives with toner particles.

[0152] By adding and mixing external additives to toner particles, the resulting toner particles can be given properties such as fluidity, electrostatic properties, and cleaning properties.

[0153] There are no particular restrictions on the mixing method, and it can be appropriately selected depending on the purpose. For example, methods include applying impact force to the mixture with a rapidly rotating blade, or introducing the mixture into a high-speed airflow, accelerating it, and causing the particles or composite particles to collide with a suitable impact plate.

[0154] Methods of mixing include, for example, an Ongmill (manufactured by Hosokawa Micron Corporation), a modified I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) with reduced grinding air pressure, a hybridization system (manufactured by Nara Machine Works Co., Ltd.), a cryptron system (manufactured by Kawasaki Heavy Industries Co., Ltd.), and an automatic mortar and pestle.

[0155] [External Additives] Examples of external additives include inorganic microparticles, polymer microparticles, fluidity enhancers, and cleaning aids.

[0156] (Inorganic fine particles) Examples of inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

[0157] The average primary particle size of the inorganic fine particles is preferably 5 nm to 2 μm, and more preferably 5 nm to 500 nm. Here, the average primary particle size refers to the average value obtained by measuring the particle size of 500 arbitrary particles from a scanning electron microscope image of the inorganic fine particles dispersed in isopropyl alcohol, which is dropped onto a measurement sample stage, and after drying, using a Hitachi Technologies Ltd. "S-4800".

[0158] The specific surface area of ​​inorganic nanoparticles obtained by the BET method is 20 m². 2 / g~500m 2 / g is preferable.

[0159] The inorganic fine particle content is preferably 0.01% to 5% by mass relative to the total amount of toner.

[0160] (Polymer-based fine particles) Examples of polymer-based microparticles include polymer particles made from polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, or dispersion polymerization, as well as polymer particles made from polycondensation systems such as methacrylic acid esters and acrylic acid ester copolymers, silicon, benzoguanamine, and nylon, and thermosetting resins.

[0161] (Flow improver) As a fluidity improver, there are no particular restrictions as long as it can be surface-treated to increase hydrophobicity and prevent deterioration of fluidity and electrostatic properties even under high humidity conditions, and can be appropriately selected according to the purpose. Specifically, examples include silane coupling agents, silylation agents, silane coupling agents having alkyl fluoride, organic titanate coupling agents, aluminum coupling agents, silicone oil, and modified silicone oil.

[0162] It is particularly preferable to surface-treat silica and titanium oxide with such fluidity improvers and use them as hydrophobic silica and hydrophobic titanium oxide.

[0163] (Cleaning aid) Cleaning aids are not particularly limited as long as they are added to toner to remove residual post-transfer developer from the photoreceptor and primary transfer medium, and can be appropriately selected according to the purpose. Specifically, examples include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, polymer microparticles produced by soap-free emulsion polymerization such as polymethyl methacrylate microparticles and polystyrene microparticles.

[0164] As polymer fine particles, those with a relatively narrow particle size distribution are preferred, and those with a volume-average particle size of 0.01 μm to 1 μm are preferred. [Examples]

[0165] The present invention will be described more specifically below based on examples, but the present invention is not limited to the following examples. Note that "parts" are based on mass.

[0166] <Synthesis of polyester resin 1> In a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet, a diol component consisting of 2 mol ethylene oxide adduct of bisphenol A and 3 mol propylene oxide adduct of bisphenol A (molar ratio 40 / 60), a dicarboxylic acid component consisting of terephthalic acid and adipic acid (molar ratio 85 / 15), and 3.5 mol% trimethylolpropane relative to the total amount of monomer were added so that the molar ratio of hydroxyl groups to carboxylic acid (-OH / -COOH) was 1.2.

[0167] Furthermore, tetrabutyl orthotitanate was added as a condensation catalyst at a concentration of 1000 ppm relative to the total amount of monomer, and the mixture was heated to 230°C over 2 hours under a nitrogen atmosphere, while the reaction was carried out for 5 hours, with the water produced being removed by distillation.

[0168] Subsequently, the mixture was reacted under reduced pressure of 5 mmHg to 15 mmHg for 4 hours, cooled to 180°C, and then 1.0 mol% trimellitic anhydride and 200 ppm tetrabutyl orthotitanate relative to the total amount of monomer were added. The mixture was reacted at atmospheric pressure at 180°C for 1 hour, and then further reacted under reduced pressure of 5 mmHg to 20 mmHg for 3 hours to obtain [Polyester Resin 1].

[0169] <Creating Masterbatch 1 for Toner> Polyester resin and PY185 were pre-mixed in a 1:1 mass ratio using a Henschel mixer (Mitsui Miike Chemical Machinery Co., Ltd., FM20B), and then melted and kneaded at 130°C using a twin-screw kneader (Ikegai Co., Ltd., PCM30). The resulting kneaded material was rolled to a thickness of 2.7 mm using rollers, cooled to room temperature using a belt cooler, and then coarsely ground to 200 μm to 300 μm using a hammer mill to obtain [Toner Masterbatch 1].

[0170] <Synthesis of Prepolymer 1> In a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube, 682 parts of bisphenol A ethylene oxide 2 molar adduct, 81 parts of bisphenol A propylene oxide 2 molar adduct, 283 parts of terephthalic acid, 22 parts of trimellitic anhydride, and 2 parts of dibutyltin oxide were charged and reacted at atmospheric pressure at 230°C for 8 hours.

[0171] Next, the mixture was reacted under reduced pressure of 10 mmHg to 15 mmHg for 5 hours to synthesize [Intermediate Polyester Resin 1]. Then, 410 parts of [Intermediate Polyester Resin 1], 89 parts of isophorone diisocyanate, and 500 parts of ethyl acetate were charged into a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube, and reacted at 100°C for 5 hours to obtain [Prepolymer 1].

[0172] <Preparation of Wax Emulsion 1> 100 parts of deionized water were mixed with 28 parts of HNP-9 (manufactured by Nippon Seiro) as a wax and Sanizol (registered trademark) B50 as a surfactant. This mixture was dispersed in a homogenizer while being heated to 90°C to obtain [wax emulsion 1].

[0173] <Preparation of crystalline polyester resin dispersion C1> In a 5L four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, 1,6-hexanediol and sebacic acid were charged so that the ratio of OH groups to COOH groups (-OH / -COOH) was 1.1. The mixture was reacted with 500 ppm titanium tetraisopropoxide relative to the mass of the charged raw materials, while water was being expelled. Finally, the temperature was raised to 235°C and the reaction was carried out for 1 hour.

[0174] The reaction was then carried out under reduced pressure of 10 mmHg or less for 6 hours. Subsequently, the temperature was set to 185°C, trimellitic anhydride was added in a molar ratio of 0.053 to COOH groups, and the mixture was reacted with stirring for 2 hours to obtain [crystalline polyester resin C].

[0175] 55 parts of [crystalline polyester resin C], 40 parts of methyl ethyl ketone, and 5 parts of 2-propyl alcohol were added to a four-necked flask. Then, the mixture was heated and stirred at the melting point of [crystalline polyester resin C] to dissolve it. Subsequently, a 28% by mass aqueous ammonia solution was added to achieve a neutralization rate of 400%. The neutralization rate was calculated from the acid value of the crystalline polyester resin.

[0176] Furthermore, 130 parts of deionized water were gradually added to perform phase inversion emulsification, followed by desolvation. Subsequently, deionized water was added to adjust the solid content concentration (concentration of crystalline polyester resin) to 25% by mass, obtaining [crystalline polyester resin dispersion C1], which is a binder resin dispersion for toner.

[0177] <Synthesis of Ketimine Compound 1> In a reaction vessel equipped with a stirring rod and thermometer, 170 parts of isophorone diamine and 75 parts of methyl ethyl ketone were charged and reacted at 45°C for 5.5 hours to obtain [ketimine compound 1].

[0178] <Toner production> (Example 1) <Oil phase preparation process, phase inversion emulsification process> In a four-necked flask, 100 parts of [polyester resin 1], 10 parts of [prepolymer 1], and 10 parts of [toner masterbatch 1] were added to 120 parts of ethyl acetate and stirred to dissolve and disperse. Then, while stirring, 5 parts of 28% by mass aqueous ammonia solution were added to prepare an oil phase with a neutralization rate of 400%. 340 parts of ion-exchanged water were gradually added to perform phase inversion emulsification. After that, desolvation was performed to obtain [slurry 1].

[0179] The particle size of [Slurry 1] was measured to be 0.50 μm. The solid content concentration was measured to be 23.0%.

[0180] <Agglomeration process, fusion process> 100 parts of [Slurry 1], 5.0 parts of [Crystalline polyester resin dispersion C1], 5.0 parts of [Wax emulsion 1], and 300 parts of deionized water were placed in a container and stirred for 1 minute. Next, 20 parts of 5% aluminum sulfate solution were added dropwise to the solid content and stirred for a further 5 minutes, after which the temperature was raised to 60°C. After that, when the particle size reached 5.0 μm, 40 parts of sodium chloride were added to induce flocculation, and the mixture was heated to 70°C while stirring until the desired circularity of 0.96 was achieved, at which point it was cooled to obtain [Toner dispersion 1].

[0181] <Washing and drying process, annealing process> [Toner dispersion 1] was stored at 45°C for 10 hours, then filtered under reduced pressure, and washed and dried as follows. (1): 100 parts of deionized water were added to the filter cake, mixed with a TK homomixer (rotating at 12,000 rpm for 10 minutes), and then filtered. (2): 900 parts of deionized water were added to the filtration cake from (1), and the mixture was mixed in a TK homomixer with ultrasonic vibration (at a rotation speed of 12,000 rpm for 30 minutes), followed by vacuum filtration. This operation was repeated until the electrical conductivity of the slurry was 10 μC / cm or less, and then filtered to obtain [filtration cake 1].

[0182] [Filter cake 1] was dried in a circulating air dryer at 45°C for 72 hours, and then sieved with a 75 μm mesh to obtain [colored resin particles 1].

[0183] <External addition process> [Colored resin particles 1] was mixed with 2.5 parts of TS530, an inorganic fine particle manufactured by Cabosil, in 100 parts, and mixed in a Henschel mixer at 40 m / s for 10 minutes to obtain [Toner 1].

[0184] (Example 2) In the aggregation and fusion process, the metal salt solution used was changed from a 5% aluminum sulfate solution to a 5% magnesium chloride solution. Otherwise, the toner of Example 2 was obtained in the same manner as in Example 1.

[0185] (Example 3) The toner of Example 3 was obtained in the same manner as in Example 1, except that a styrene-acrylic copolymer resin with a specific gravity of 1.05 (BR-83, manufactured by Mitsubishi Rayon Co., Ltd.) was used instead of polyester resin 1.

[0186] (Example 4) In the aggregation and fusion process, the metal salt solution used was changed from a 5% aluminum sulfate solution to a 5% potassium chloride solution. Otherwise, the toner of Example 4 was obtained in the same manner as in Example 1.

[0187] (Example 5) The toner of Example 5 was obtained in the same manner as in Example 1, except that a prepolymer was not added.

[0188] (Comparative Example 1) The toner for Comparative Example 1 was obtained in the same manner as in Example 1, except that PY185 was added instead of toner masterbatch 1.

[0189] (Comparative Example 2) The toner for Comparative Example 2 was obtained in the same manner as for Comparative Example 1, except that CIPigment Yellow 139 was added instead of PY185.

[0190] (Comparative Example 3) Toner for Comparative Example 3 was obtained in the same manner as for Comparative Example 1, except that a styrene-acrylic copolymer resin with a specific gravity of 1.05 (BR-83, manufactured by Mitsubishi Rayon Co., Ltd.) was used instead of polyester resin, and no prepolymer was added.

[0191] (Comparative Example 4) The toner for Comparative Example 4 was obtained in the same manner as in Example 1, except that [Toner Dispersion 2] described below was used.

[0192] <Preparation of the aqueous phase> 963 parts of water, 37 parts of a 48.3% aqueous solution of sodium dodecyldiphenyl ether disulfonate (Eleminol® MON-7, manufactured by Sanyo Chemical Industries, Ltd.), and 90 parts of ethyl acetate were mixed and stirred to obtain a milky white [aqueous phase 1].

[0193] <Preparation of the oil phase> In a container equipped with a stirring rod and thermometer, 120 parts of paraffin wax (melting point 90°C), 446 parts of [crystalline polyester resin dispersion C1], and 1894 parts of ethyl acetate were charged. The mixture was heated to 80°C under stirring and maintained at 80°C for 5 hours, then cooled to 30°C in 1 hour. Next, 250 parts of pigment PY185 and 1000 parts of ethyl acetate were charged into the container and mixed for 1 hour to obtain [raw material solution]. 1324 parts of [raw material solution] were transferred to a container, and the pigment and wax were dispersed using a bead mill (Ultraviscomill, manufactured by AIMEX) under the conditions of a liquid transfer rate of 1 kg / hr, a disk peripheral speed of 6 m / sec, and 80% by volume filling of 0.5 mm zirconia beads, in 5 passes, to obtain [pigment / wax dispersion 1].

[0194] <Emulsification process, solvent removal process> 375 parts of [Pigment / Wax Dispersion 1], 500 parts of [Prepolymer 1], and 15 parts of [Ketimine Compound 1] were placed in a container and mixed at 5000 rpm for 5 minutes using a TK Homo Mixer (manufactured by Tokushu Kika Co., Ltd.). Then, 1200 parts of [Aqueous Phase 1] were added to the container and mixed at 10000 rpm for 1.5 hours using a TK Homo Mixer to obtain [Emulsified Slurry 1].

[0195] [Emulsified slurry 1] was added to a container equipped with a stirrer and thermometer, and after desolvation at 30°C for 8 hours, [toner dispersion 2] was obtained.

[0196] <Rating> The toners prepared in Examples 1-5 and Comparative Examples 1-4 were evaluated as follows. The results are shown in Table 1.

[0197] [Coloring degree] After developing an aluminum substrate using two-component developers in a cascade process to achieve a toner deposition of 0.3 mg / cm², the image was electrostatically transferred from the aluminum substrate to Tokubishi Art double-sided paper and fixed at a fixing temperature of 180°C using a belt fuser (linear speed 282 mm / sec, nip time 40.1 msec, nip pressure 37 N / cm²).

[0198] For the images, the degree of coloration (ID measurement using X-Rite Model 938) was measured. (Evaluation Criteria) A color ID of 1.55 or higher was rated as excellent (A), 1.50 or higher and less than 1.55 as good (B), 1.45 or higher and less than 1.50 as average (C), and less than 1.45 as poor (D). A, B, and C were considered to be at a usable level, while D was considered not at a usable level. The evaluation results are shown in Table 1.

[0199] [Charge stability] A modified commercially available digital full-color printer (Ricoh imagio Neo C455) was loaded with developer, and a run evaluation was conducted on 300,000 image charts with a 50% image area in single-color mode.

[0200] Then, the charge stability was determined by the change in the charge amount of the carrier after this run. Here, the change in charge amount is as follows:

[0201] Specifically, |Q1-Q2| refers to a sample that has been humidified in an open system for more than 30 minutes under conditions of 23°C and 50% relative humidity (M / M environment), with an initial carrier of 6,000g and toner of 0.452g added to a stainless steel container, sealed, and operated for 5 minutes at a scale of 150 using a YS-LD (Yayoi Corporation shaker) to induce triboelectric charging by approximately 1,100 shakes. The amount of charge measured using a general blow-off method (Toshiba Chemical Corporation: TB-200) is defined as Q1, and the amount of charge measured using the same method for the carrier obtained after removing the toner in the developer using a blow-off device is defined as Q2.

[0202] The evaluation was conducted based on the following criteria. A, B, and C were considered to be at a usable level, while D was considered not to be at a usable level. The evaluation results are shown in Table 1. (Evaluation Criteria) A: Change in charge amount is less than 10 μc / g B: Change in charge amount is 10 μC / g or more, but less than 15 μC / g. C: Change in charge amount is 15 μC / g or more, and less than 20 μC / g. D: Change in charge amount is 20 μC / g or more

[0203] Table 1 shows that in Examples 1-5, both the degree of coloration and the electrostatic stability were at a practical level. In contrast, in Comparative Examples 1-4, at least one of the degree of coloration or electrostatic stability did not meet a practical level.

[0204] [Table 1]

[0205] As described above, embodiments have been explained, but these embodiments are presented as examples only, and the present invention is not limited by these embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Prior art documents] [Patent Documents]

[0206] [Patent Document 1] Japanese Patent Publication No. 2008-70466

Claims

1. A method for producing toner particles comprising a coloring agent, a binder resin, and a wax, The aforementioned binder resin comprises one or more resins, A step of preparing a toner masterbatch comprising at least the coloring agent, one or more of the resins, and the wax, A step of dissolving or dispersing the toner masterbatch in an organic solvent to prepare an oil phase, A step of adding an aqueous medium to the oil phase to perform phase inversion emulsification and obtaining an oil-in-water dispersion in which the oil phase is dispersed, The process involves removing the solvent from the oil-in-water dispersion to obtain a dispersion in which fine particles are dispersed, The process includes adding a coagulant to a dispersion in which the fine particles are dispersed, thereby causing the fine particles to coagulate. The aforementioned coloring agent is C.I. Pigment Yellow 185. A method for producing toner particles, characterized in that the flocculant is a metal salt.

2. The method for producing toner particles according to claim 1, characterized in that the binder resin includes a polyester resin.

3. The method for producing toner particles according to claim 1 or 2, characterized in that the metal salt is a salt of a metal with a valency of 2 or higher.

4. A method for producing toner particles according to any one of claims 1 to 3, characterized in that the binding resin comprises a prepolymer and a resin obtained by at least crosslinking or stretching the prepolymer.

5. A method for producing toner particles according to any one of claims 1 to 4, characterized in that, in the step of preparing the oil phase, a prepolymer and a resin obtained by at least crosslinking or stretching the prepolymer are added to the organic solvent.

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