Polyester resin emulsion for toner, method for producing resin particles and method for producing toner

Abstract

To provide a polyester resin emulsion for toner having a core-shell structure, capable of acquiring toner having excellent heat-resistant storage stability, and having excellent cohesiveness of core particles and shell particles and uniform fusibility of the shell particles to the core particles during production.SOLUTION: A polyester resin emulsion for toner is formed by dispersing, in an aqueous medium, resin particles (S) containing a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component. The alcohol component contains a trihydric or tetrahydric alcohol having a skeleton of a linear or branched aliphatic saturated hydrocarbon having 4 or more and 6 or less carbon atoms, the polyester resin (A) contains a sulfonate group, and when an acid value of the polyester resin (A) is AV (mgKOH / g) and a hydroxyl value of the polyester resin (A) is OHV (mgKOH / g), OHV / AV is 0.4 or more and 1.1 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester resin emulsion for toner, a method for producing resin particles, and a method for producing toner. [Background technology]

[0002] Toners used in electrophotographic image forming apparatuses are required to have excellent low-temperature fixing properties in response to market demands for energy conservation. Furthermore, toners are also required to have excellent anti-blocking properties, which prevent toner particles from fusing together even in harsh environments such as high temperature and humidity, and toners with excellent mechanical durability that can fully withstand the stresses associated with increasing output speeds of image forming apparatuses.

[0003] In recent years, there has been progress in the development of toners having a so-called core-shell structure, in which a shell layer is provided on the surface of the toner for the purpose of imparting heat resistance and mechanical durability. Various techniques for forming a core-shell toner have been proposed and put into practical use, but chemical toners in which polyester resins with excellent low-temperature fixability are used for both the core particles and the shell particles are mainstream.

[0004] For example, a toner for electrostatic charge development has been proposed in which polyethylene terephthalate (PET) is blended with the resin in the core and shell (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a polyester resin emulsion for toners that has a core-shell structure, can produce a toner with excellent heat-resistant storage stability, and is excellent in the cohesion of core particles and shell particles during production and in the uniform fusion of shell particles to core particles. [Means for solving the problem]

[0006] The polyester resin emulsion for toner of the present invention, which is a means for solving the above-mentioned problems, has the following constitution. A polyester resin emulsion for toner, comprising resin particles (S) dispersed in an aqueous medium, the resin particles (S) including a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component, the alcohol component contains a trihydric or tetrahydric alcohol having a linear or branched aliphatic saturated hydrocarbon skeleton having 4 to 6 carbon atoms, the polyester resin (A) contains a sulfonate group, and when the acid value of the polyester resin (A) is AV (mg KOH / g) and the hydroxyl value of the polyester resin (A) is OHV (mg KOH / g), OHV / AV is 0.4 or more and 1.1 or less; A polyester resin emulsion characterized by: [Effects of the Invention]

[0007] According to the present invention, it is possible to obtain a toner having a core-shell structure and excellent heat-resistant storage stability, and it is also possible to provide a polyester resin emulsion for a toner that is excellent in the cohesion of core particles and shell particles during production and in the uniform fusion of shell particles to core particles. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] It is known that in a toner having a core-shell structure, from the viewpoints of low-temperature fixability, heat-resistant storage stability, and mechanical durability of the toner, it is very important that the shell formed on the surface of the core particle is uniformly distributed and has no defects. More specifically, if the shell is not uniformly distributed on the surface of the core particle and has no defects, the mechanical durability of the toner will decrease, and there is a concern that the shell will peel off from the core particle due to development stress in an image forming apparatus, etc., and each toner performance will be significantly deteriorated.

[0010] In the prior art described in Patent Document 1, polyethylene terephthalate (PET) is introduced into the shell portion of a toner having a core-shell structure to improve the durability of the toner and suppress exposure of wax on the toner surface. However, there is concern that introducing polyethylene terephthalate (PET) into the shell particles that form the shell portion reduces the hydrophobicity of the shell particles, thereby reducing the cohesiveness of the core particles and shell particles, making it difficult to form a uniform shell on the surface of the core particles.

[0011] To produce a uniform shell, it is necessary to give the shell particles cohesive properties and cause hetero-coagulation on the surface of the core particles. However, if a shell has strong cohesive properties, it will adhere to the core surface, which will also increase the cohesive properties of the core. During the shell fusion process at high temperatures, the shell may become incorporated into the core and aggregate.

[0012] The present inventors have conducted extensive research and have found that when forming a core-shell structure, i.e., when aggregating shell particles onto the surface of core particles, using an emulsion of a polyester resin dispersed in an aqueous medium, the polyester resin (A) containing a sulfonate group and a specific alcohol component and having a ratio of the hydroxyl value (OHV) of the polyester resin (A) to the acid value (AV) within an appropriate range, improves the aggregability of the core particles and shell particles during fusion, improves the uniform fusion of the shell particles to the core particles, and results in a toner with excellent heat-resistant storage stability. Specifically, this is as follows.

[0013] When preparing a toner having a core-shell structure by aggregating shell particles on the surface of core particles, a resin emulsion containing shell particles is dispersed in a dispersion liquid in which core particles are dispersed, and aggregation is carried out by utilizing collision energy between particles due to stirring, thermal energy due to heating, or an aggregating agent such as an inorganic metal salt. Here, the properties of the resin constituting the shell particles not only affect the stability of the emulsion and the aggregability with the core particles, but also affect the adhesion with the core particles when the shell particles are heat-fused to form a shell. Typical properties of the resin that constitutes the shell particles include acid value (AV), hydroxyl value (OHV), hydrophilicity / hydrophobicity, affinity with solvents, and melt viscosity. In order to effectively control hetero-aggregation of shell particles with core particles, it is effective to include, as the alcohol component, a trihydric or tetrahydric alcohol having a skeleton of a linear or branched saturated fatty acid having 4 to 6 carbon atoms. In addition, adding a sulfonate group is effective for stabilizing shell particles at high temperatures. As a result of examining the above control factors, it was found that a polyester resin containing a sulfonate group, having a hydroxyl value (OHV) to acid value (AV) ratio (OHV / AV) of 0.4 or more and 1.1 or less, and containing a trihydric or tetrahydric alcohol as the alcohol component, with a linear or branched saturated fatty acid skeleton having 4 to 6 carbon atoms, improves the cohesion of the core particles and shell particles during fusion, thereby improving the uniform fusion of the shell particles to the core particles.

[0014] The present invention will be described in detail below.

[0015] (Polyester resin emulsion for toner) The polyester resin emulsion for toner of the present invention is an emulsion in which resin particles (S) containing a polyester resin (A) are dispersed in an aqueous medium, and may contain other resins and other components as necessary.

[0016] <Resin particles (S)> The resin particles (S) contain a polyester resin (A) and may contain other components as needed.

[0017] [Volume average particle size of resin particles (S)] The volume average particle size of the resin particles (S) in the polyester resin emulsion for toner is not particularly limited and can be appropriately selected depending on the purpose. The median diameter (D50) is preferably 0.05 μm or more and 0.8 μm or less, more preferably 0.1 μm or more and 0.5 μm or less, and even more preferably 0.15 μm or more and 0.3 μm or less. When the volume average particle size of the resin particles (S) is 0.05 μm or more in terms of median diameter (D50), the aggregation efficiency of the shell particles relative to the core particles is good, and a shell with sufficient thickness can be formed on the toner surface, which is preferable. When the volume average particle size of the resin particles (S) is 0.8 μm or less in terms of median diameter (D50), the aggregation of the shell particles to the core particles becomes uniform, and a sufficiently uniform shell can be formed, which is preferable.

[0018] The method for measuring the median diameter (D50) is not particularly limited and can be appropriately selected depending on the purpose. For example, the median diameter can be measured using a laser particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.).

[0019] <<Polyester resin (A)>> The polyester resin (A) is a polyester resin obtained by polycondensation of an alcohol component and a carboxylic acid component, and may contain other alcohols, repeating units derived from polyethylene terephthalate (PET), and other components, as necessary.

[0020] <<<Alcohol content>>> The alcohol component contains a trihydric or tetrahydric alcohol having a skeleton of a linear or branched saturated fatty acid having 4 to 6 carbon atoms. In this specification, "a trihydric or tetrahydric alcohol having a straight-chain or branched saturated fatty acid skeleton with 4 to 6 carbon atoms" may be simply referred to as "alcohol." Note that alcohols that do not fall under the category of "a trihydric or tetrahydric alcohol having a straight-chain or branched saturated fatty acid skeleton with 4 to 6 carbon atoms" may be referred to as "other alcohols." In this specification, the term "linear" refers to a structure that does not have any bonds between carbon atoms other than a carbon chain (hereinafter sometimes referred to as "main chain") that connects two oxygen atoms appropriately selected from oxygen atoms derived from hydroxyl groups in the monomer unit of the alcohol component with the minimum number of bonds between them. In this specification, the term "branched" refers to a structure having carbon-carbon bonds in addition to the main chain.

[0021] When the polyester resin (A) contains, as an alcohol component, a trihydric or tetrahydric alcohol having a linear or branched saturated aliphatic skeleton having 4 to 6 carbon atoms, the hydroxyl value (OHV) of the polyester resin (A) can be controlled and the cohesiveness and adhesion to the core particles can be improved.

[0022] The alcohol is not particularly limited as long as it has a straight-chain or branched saturated fatty acid skeleton having 4 to 6 carbon atoms and is trivalent or tetravalent, and can be appropriately selected depending on the purpose, and examples thereof include trivalent aliphatic alcohols having 4 to 6 carbon atoms and tetravalent aliphatic alcohols having 4 to 6 carbon atoms. Examples of the trivalent aliphatic alcohols having 4 to 6 carbon atoms include 1,2,3-butanetriol, 1,2,4-butanetriol, trimethylolethane, 1,2,3-pentanetriol, 1,2,4-pentanetriol, 1,2,5-pentanetriol, 1,3,5-pentanetriol, 2,3,4-pentanetriol, trimethylolpropane, 1,2,3-hexanetriol, 1,2,6-hexanetriol, 1,3,5-hexanetriol, and 2-isopropylpropane-1,2,3-triol. Examples of the tetrahydric aliphatic alcohol having 4 to 6 carbon atoms include pentaerythritol, 1,2,3,4-butanetetraol, 1,2,3,4-pentanetetraol, 1,2,3,5-pentanetetraol, 1,2,4,5-pentanetetraol, 1,2,4,5-hexanetetraol, and 1,2,5,6-hexanetetraol. These alcohols may be used alone or in combination of two or more.

[0023] The content of the alcohol is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.5 mol % or more and 10 mol % or less based on the total amount of alcohol components in the polyester resin (A). If the content of the alcohol is 0.5 mol% or more relative to the total amount of alcohol components in the polyester resin (A), the problem of insufficient cohesion of the shell particles relative to the core particles, resulting in an increase in shell particles not incorporated into the shell, can be solved, which is advantageous. When the content of the alcohol is 10 mol % or less based on the total amount of alcohol components in the polyester resin (A), the branched chains of the polyester resin (A) increase, and the melt viscosity of the shell in the toner decreases, which is a problem that sufficient heat-resistant storage stability and hot offset resistance cannot be obtained, and this is preferable.

[0024] <<<Carboxylic Acid>>> The carboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include aliphatic dicarboxylic acids or anhydrides thereof such as succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, maleic acid, citraconic acid, itaconic acid, alkenylsuccinic acid, and fumaric acid; trivalent or higher carboxylic acids such as 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, tetra(methylenecarboxy)methane, and 1,2,7,8-octanetetracarboxylic acid; Examples of the aromatic dicarboxylic acids include aliphatic carboxylic acids or their anhydrides; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid or their anhydrides; and trivalent or higher aromatic carboxylic acids such as trimellitic acid, pyromellitic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, and 1,2,4-naphthalenetricarboxylic acid or their anhydrides, and partial lower alkyl esters. These carboxylic acids may be used alone or in combination of two or more.

[0025] The method for polycondensation of the alcohol component and the carboxylic acid component is not particularly limited and can be appropriately selected depending on the purpose. For example, the method can be carried out in an inert gas atmosphere in the presence of an esterification catalyst at a temperature of 180°C to 250°C.

[0026] The esterification catalyst is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include titanium compounds and tin(II) compounds that do not have an Sn—C bond. These esterification catalysts may be used alone or in combination of two or more.

[0027] The titanium compound is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include titanium diisopropylate bistriethanolaminate, titanium diisopropylate bistriethanolaminate, titanium dipentylate bistriethanolaminate, titanium diethylate bistriethanolaminate, titanium dihydroxyoctylate bistriethanolaminate, titanium distearate bistriethanolaminate, titanium triisopropylate triethanolaminate, titanium monopropylate tris(triethanolaminate), tetra-n-butyl titanate, tetrapropyl titanate, tetrastearyl titanate, tetramyristyl titanate, tetraoctyl titanate, dioctyl dihydroxyoctyl titanate, and dimyristyl dioctyl titanate. Among these, titanium compounds having a Ti—O bond are preferred from the viewpoint of high activity and ability to reduce low-molecular-weight components in the polyester resin, and compounds having an alkoxy group, alkenyloxy group, or acyloxy group having a total of 1 to 28 carbon atoms are more preferred.

[0028] The content of the titanium compound is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of controllability of the reaction rate in the polymerization and ensuring the quality of the polyester resin, the content is preferably 0.01 parts by mass or more and 1.0 parts by mass or less, and more preferably 0.1 parts by mass or more and 0.5 parts by mass or less, relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0029] The tin(II) compound not having an Sn-C bond is not particularly limited and can be appropriately selected depending on the purpose, but a tin(II) compound having an Sn-O bond or a tin(II) compound having an Sn-X (X represents a halogen atom) bond is preferred, and a tin(II) compound having an Sn-O bond is more preferred. Examples of tin(II) compounds having an Sn-O bond include tin(II) oxalate, tin(II) acetate, tin(II) octoate, tin(II) 2-ethylhexanoate, tin(II) laurate, tin(II) stearate, and tin(II) oleate, as well as other tin(II) carboxylates having a carboxylic acid group with 2 to 28 carbon atoms; alkoxytin(II) having an alkoxy group with 2 to 28 carbon atoms, such as octyloxytin(II), lauroxytin(II), stearoxytin(II), and oleyloxytin(II); tin(II) oxide; and tin(II) sulfate. Examples of tin(II) compounds having an Sn-X bond include tin(II) halides such as tin(II) chloride and tin(II) bromide.

[0030] The content of the tin(II) compound is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of controllability of the reaction rate in the polymerization and ensuring the quality of the polyester resin, the content is preferably 0.01 parts by mass or more and 1.0 parts by mass or less, and more preferably 0.1 parts by mass or more and 0.5 parts by mass or less, relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0031] When the titanium compound and the tin(II) compound are used in combination, the total content of the titanium compound and the tin(II) compound is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of controllability of the reaction rate in polymerization and ensuring the quality of the polyester resin, the total content of the alcohol component and the carboxylic acid component is preferably 0.01 parts by mass or more and 1.0 parts by mass or less, and more preferably 0.1 parts by mass or more and 0.5 parts by mass or less, per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0032] <<<Other alcohol>>> The polyester resin (A) in the present invention may contain other alcohols in addition to the above alcohols. The other alcohol is not particularly limited and can be appropriately selected depending on the purpose. Examples of the other alcohol include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-dodecanediol; diols having an oxyalkylene group such as diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol, 1,4-sorbitan, and hydrogenated bisphenol A; and the other alcohols. Examples of the alkylene oxide adducts include those obtained by adding alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to cyclic diols; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; alkylene oxide adducts of bisphenols such as those obtained by adding alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to the above bisphenols; tri- or higher hydric aliphatic alcohols such as heptanetriol, octanetriol, decanetriol, sorbitol, and dipentaerythritol; polyphenols such as trisphenol, phenol novolac, and cresol novolac; and alkylene oxide adducts of polyphenols such as those obtained by adding alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to the above polyphenols. Among these, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol are preferred. By using these diols as the other alcohol component in the polyester resin (A), a shell having an excellent balance between low-temperature fixability and mechanical durability can be formed, and the cohesion of the shell particles relative to the core particles and the uniformity of the shell particles can be improved. Furthermore, from the viewpoint of reducing carbon dioxide emissions when the resulting toner is ultimately incinerated, it is more preferred that these diols be derived from biomass. In this specification, "1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol" may be referred to as "diol (D)." These other alcohols may be used alone or in combination of two or more.

[0033] When 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol are used as the other alcohols, the content of at least one selected from these diols is preferably 30 mol% or more, more preferably 50 mol% or more, and even more preferably 80 mol% or more, based on the total amount of the alcohol components in the polyester resin (A). In other words, the total content of these diols is preferably 30 mol% or more, more preferably 50 mol% or more, and even more preferably 80 mol% or more, based on the total amount of the alcohol components in the polyester resin (A). It is preferable that the total content of 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol is 30 mol% or more relative to the total amount of alcohol components in the polyester resin (A), because low-temperature fixability, mechanical durability, and an effect of reducing environmental impact can be obtained.

[0034] <<<Repeating units derived from polyethylene terephthalate (PET)>>> In addition to the above components, the polyester resin (A) of the present invention may contain repeating units derived from so-called polyethylene terephthalate (PET), which is a condensate of terephthalic acid and ethylene glycol. In this specification, "repeating units derived from polyethylene terephthalate (PET)" may also be referred to as "PET repeating units." The polyester resin (A) containing the PET repeating unit has excellent mechanical durability and can be suitably used for the shell of a toner having a core-shell structure. From the viewpoint of reducing the environmental load, such as reducing the consumption of petroleum resources, it is preferable to use recycled PET as the raw material.

[0035] The polyester resin (A) containing the PET repeating unit can be obtained by polycondensation while causing an ester exchange reaction with the above-mentioned polyester resin (A) material.

[0036] The content of the PET repeating unit is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably 10% by weight or more and 70% by weight or less, and more preferably 30% by weight or more and 60% by weight or less, based on the total amount of the polyester resin (A). If the content of the PET repeating unit is 10% by weight or more based on the total amount of the polyester resin (A), excellent mechanical durability is obtained, which is preferable. If the content of the PET repeating unit is 70% by weight or less based on the total amount of the polyester resin (A), this is preferable because the solubility in organic solvents and the low-temperature fixability are improved.

[0037] [Ratio of polyester resin (A) (OHV / AV)] In the present invention, the ratio (OHV / AV) of the hydroxyl value (OHV) of the polyester resin (A) to the acid value (AV) of the polyester resin (A) must be 0.4 or more and 1.1 or less, and more preferably 0.5 or more and 0.7 or less. By making the ratio (OHV / AV) 0.4 or more and 1.1 or less, the hetero-aggregation of the shell particles to the core particles and the aggregation of the core particles and shell particles when heated at high temperatures are improved, and the uniform fusion of the shell particles to the core particles is improved, which is suitable for obtaining a toner with excellent heat-resistant storage stability.

[0038] The acid value (AV) of the polyester resin (A) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 mgKOH / g or more and 25 mgKOH / g or less, and more preferably 17 mgKOH / g or more and 20 mgKOH / g or less. If the acid value (AV) is less than 10 mgKOH / g, the emulsion will be less stable and will be difficult to emulsify. If the oxidation value (AV) exceeds 25 mgKOH / g, the emulsion becomes too stable, which may reduce the hetero-aggregation of the shell particles to the core particles, resulting in poor shell formation.

[0039] The method for measuring the acid value (AV) of the polyester resin (A) is not particularly limited and can be appropriately selected depending on the purpose. For example, it can be measured by the following method in accordance with JIS K0070-1992.

[0040] 0.5 g of resin (0.3 g of ethyl acetate soluble matter) was added to 120 mL of toluene and dissolved by stirring at room temperature (23°C) for about 10 hours. Further, 30 mL of ethanol was added to prepare a sample solution. The acid value of the sample solution was measured at 23°C using an automatic potentiometric titrator (DL-53 Titrator, Mettler-Toledo) and an electrode DG113-SC (Mettler-Toledo), and the results were analyzed using the analytical software LabX Light Version 1.00.000. A mixed solvent of 120 mL of toluene and 30 mL of ethanol was used in the apparatus. The measurement can be carried out by the above-mentioned measurement method, but specifically, the acid value was calculated as follows: Titration was carried out in advance with a standardized 0.1 N potassium hydroxide / alcohol solution, and the acid value was calculated from the titration amount using the following formula. Acid value [mgKOH / g] = titration amount [mL] × N × 56.1 [mg / mL] / sample mass [g] (In the above formula, "N" represents the factor of a 0.1N potassium hydroxide / alcohol solution.)

[0041] The hydroxyl value (OHV) of the polyester resin (A) is preferably 5 mgKOH / g or more and 19 mgKOH / g or less when the acid value (AV) is 10 mgKOH / g or more and 25 mgKOH / g or less. If the hydroxide (OHV) is less than 5 mgKOH / g, the coagulation properties of the emulsion particles will be weak, and hetero-coagulation to the core particles will be less likely to occur during shell formation. If the hydroxyl group (OHV) exceeds 19 mgKOH / g, the emulsion particles will have a strong tendency to aggregate, and homo-aggregation of emulsion particles will easily occur.

[0042] The method for measuring the hydroxyl value (OHV) of the polyester resin (A) is not particularly limited and can be appropriately selected depending on the purpose. For example, it can be measured by the following method in accordance with JIS K0070-1992.

[0043] Place 25 g of acetic anhydride in a 100 mL volumetric flask, add pyridine to bring the total volume to 100 mL, and shake thoroughly to prepare the acetyl reagent. Weigh 2 g of resin into a 200 mL flat-bottom flask and add 5 mL of the acetylation reagent using a pipette. Attach an air condenser to the neck of the flat-bottom flask and immerse approximately 1 cm of the bottom in a glycerin bath at 95-100°C for heating. After 1 hour, remove the flat-bottom flask from the bath and allow it to cool. Add 1 mL of water from the top of the air condenser and shake to decompose the acetic anhydride. To further complete the decomposition, heat again in the glycerin bath for 10 minutes, allow to cool, and then wash the air condenser tube with 5 mL of ethanol. 100 mL of ethanol was added as a solvent to the flat-bottom flask to prepare a measurement sample solution. The hydroxyl value of the sample solution was measured at 23°C using an automatic potentiometric titrator (DL-53 Titrator, Mettler-Toledo) and an electrode DG113-SC (Mettler-Toledo), and analyzed using analysis software LabX Light Version 1.00.000. Tetrahydrofuran (THF) was used as the solvent for the measurement. The measurement can be performed using the above-mentioned measurement method, but the hydroxyl value was specifically calculated as follows. The sample was titrated with a standardized 0.1N potassium hydroxide / ethanol solution in advance, and the hydroxyl value was calculated from the titration amount using the following formula. Hydroxyl value [mgKOH / g] = (Titer volume of blank titration [mL] - Titer volume [mL]) × N × 28.05 / Sample mass [g] + A (In the above formula, "N" represents the factor of the 0.1N potassium hydroxide / alcohol solution, and "A" represents the acid value of the resin.)

[0044] [Glass transition temperature (Tg) of polyester resin (A)] The glass transition temperature (Tg) of the polyester resin (A) at the second heating stage measured by differential scanning calorimetry (DSC) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 50° C. or higher and 80° C. or lower, and more preferably 60° C. or higher and 75° C. or lower. In this specification, the "glass transition temperature (Tg) at the second heating stage measured by differential scanning calorimetry (DSC)" may be referred to as "Tg2nd." If the Tg2nd of the polyester resin (A) is 60° C. or higher, the heat-resistant storage stability of the toner is improved, which is preferable. If the Tg2nd of the polyester resin (A) is 75° C. or less, the low-temperature fixability of the toner is improved, which is preferable.

[0045] The method for measuring the glass transition temperature (Tg) of the polyester resin (A) is not particularly limited, and can be measured, for example, using a differential scanning calorimeter (DSC) (e.g., Q-200 (manufactured by TA Instruments)). An example of the method for measuring the glass transition temperature (Tg) is as follows. -An example of how to measure glass transition temperature (Tg)- 5.0 mg of polyester resin (A) was placed in an aluminum sample pan, placed on a holder unit, and set in an electric furnace. 10 mg of alumina was used as a reference, placed in an aluminum sample pan. Under a nitrogen atmosphere, the sample was heated from 0°C to 150°C at a heating rate of 10°C / min (first heating), then cooled from 150°C to 0°C at a heating rate of 10°C / min (cooling process), and again heated to 150°C at a heating rate of 10°C / min (second heating). The endothermic and exothermic changes during the above process are measured, a graph of the temperature and the amount of endothermic heat is plotted, a DSC curve is created, and the analysis program in the Q-200 system is used to analyze it. The DSC curve from the second temperature rise is selected, and the glass transition temperature of the polyester resin (A) is determined from the intersection of the extension of the baseline of the DSC curve at a temperature lower than the enthalpy relaxation of the endothermic heat and the tangent showing the maximum slope of the enthalpy relaxation.

[0046] [Weight average molecular weight of polyester resin (A)] The weight average molecular weight (Mw) of the polyester resin (A) measured by gel permeation chromatography (GPC) is not particularly limited and can be appropriately selected depending on the purpose. 4 More than 1×10 5 Preferably, it is 1×10 or less. 4 5x10 or more 4 It is more preferable that the weight average molecular weight (Mw) is not more than 100%. In this specification, the "weight average molecular weight (Mw) measured by gel permeation chromatography (GPC)" may be simply referred to as the "weight average molecular weight (Mw)". The weight average molecular weight (Mw) of the polyester resin (A) is 0.8 × 10 4 If the amount is more than this, the mechanical durability of the toner becomes good, which is preferable. The weight average molecular weight (Mw) of the polyester resin (A) is 5 × 10 4 If it is less than this, the low temperature fixability of the toner becomes good, which is preferable.

[0047] The method for measuring the weight-average molecular weight (Mw) is not particularly limited, and can be measured using a gel permeation chromatography (GPC) measuring device (for example, HLC-8220GPC (manufactured by Tosoh Corporation)). An example of the method for measuring the weight-average molecular weight (Mw) is as follows. -An example of how to measure weight-average molecular weight (Mw)- The column used was a TSKgel SuperHZM-H 15 cm triple column (manufactured by Tosoh Corporation). The polyester resin (A) to be measured was prepared as a 0.15% by mass solution in tetrahydrofuran (THF) (containing stabilizers, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), filtered through a 0.2 μm filter, and the filtrate was used as the sample. 100 μl of the THF sample solution was injected into the measurement device and measured at a flow rate of 0.35 ml / min under an environment of 40°C. Molecular weights were calculated using a calibration curve prepared using monodisperse polystyrene standard samples. The polystyrene standard samples were prepared using Showdex STANDARD series (manufactured by Showa Denko K.K.) to prepare THF solutions of the following three types of monodisperse polystyrene standard samples (solutions A to C). Measurements were performed under the above conditions, and a calibration curve was prepared using the peak top retention time as the light scattering molecular weight of the monodisperse polystyrene standard samples. A refractive index (RI) detector was used. Solution A: S-7300 2.5mg, S-602 2.5mg, S-46 2.5mg, S-2.8 2.5mg, THF 50mL Solution B: S-3500 2.5mg, S-277 2.5mg, S-18 2.5mg, S-1.3 2.5mg, THF 50mL Solution C: S-1700 2.5mg, S-136 2.5mg, S-6.7 2.5mg, toluene 2.5mg, THF 50mL

[0048] [Sulfonate group-containing monomer] The sulfonate group-containing polyester resin is synthesized using a monomer having a sulfonate group. The sulfonate group-containing monomer is not particularly limited and can be appropriately selected depending on the purpose. Examples include a monomer having an aromatic sulfonate group and a monomer having an aliphatic sulfonate group. These may be used alone or in combination of two or more. Among these, the sulfonate group-containing monomer is preferably a monomer having an aromatic sulfonate group and having a divalent or higher carboxylic acid as a structural unit.

[0049] Examples of the aromatic sulfonate group-containing monomer having a dicarboxylic acid as a constituent unit include 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfo-2,6-naphthalenedicarboxylic acid, and sulfonates of their ester-forming derivatives [lower alkyl (C1 to C4) esters (methyl ester, ethyl ester, etc.), acid anhydrides, etc.].

[0050] Examples of the monomer having an aliphatic sulfonate group having a dicarboxylic acid as a constituent unit include sulfonates of sulfosuccinic acid or its ester-forming derivatives [lower alkyl (C1-4) esters (methyl ester, ethyl ester, etc.), acid anhydrides, etc.].

[0051] Examples of the sulfonate salt include alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts such as mono-, di-, or tri-amines having a hydroxyalkyl (C2-4) group, quaternary ammonium salts of these amines, and salts of two or more of these salts in combination. Examples of the alkali metal salt include lithium salt, sodium salt, and potassium salt. Examples of the alkaline earth metal salt include magnesium salts and calcium salts. Examples of the mono-, di-, or tri-amine having a hydroxyalkyl (C2-4) group include organic amine salts such as mono-ethylamine, di-ethylamine, tri-ethylamine, mono-ethanolamine, di-ethanolamine, tri-ethanolamine, and diethylethanolamine.

[0052] These sulfonates may be used alone or in combination of two or more. Among these, 5-sulfoisophthalic acid salt is preferred as the sulfonate, with 5-sulfoisophthalic acid sodium salt and 5-sulfoisophthalic acid potassium salt being particularly preferred.

[0053] [Mole ratio of monomer units having sulfonate groups] The molar ratio of the sulfonate group-containing monomer units in the sulfonate group-containing polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 2 mol % to 10 mol %, and more preferably 4 mol % to 8 mol %, relative to the total amount of the carboxylic acid monomers constituting the sulfonate group-containing polyester resin. When the molar ratio of the sulfonate group-containing monomer units in the sulfonate group-containing polyester resin is 2 mol % or more, emulsion particles are stabilized, the effect of suppressing homo-aggregation during shell formation is sufficiently obtained, and aggregation of core-shell particles is also suppressed during the process of fusing the shell particles to the core, allowing for good shell formation. When the molar ratio of the monomer unit having a sulfonate group in the polyester resin having a sulfonate group is 10 mol % or less, the moisture absorption of the sulfonate group is not strongly exhibited, and sufficient heat-resistant storage stability is also obtained.

[0054] The molar ratio of the monomer unit having a sulfonate group in the polyester resin having a sulfonate group can be measured by substituting the area of a chromatogram derived from the monomer having a sulfonate group, obtained by pyrolysis gas chromatography (pyrolysis GC), into the calibration curve equation for the monomer having a sulfonate group.

[0055] The content of the sulfonate group-containing polyester resin in the resin microparticles is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5% by mass to 40% by mass, and more preferably 10% by mass to 40% by mass, relative to the total mass of the resin microparticles. When the content of the sulfonate group-containing polyester resin is 5% by mass or more, a sufficient effect on heat-resistant storage stability is obtained. Furthermore, when the content of the sulfonate group-containing polyester resin is 40% by mass or less, sufficient low-temperature fixability is obtained.

[0056] The presence of the sulfonate group-containing polyester resin in the resin microparticles can be confirmed, for example, by measuring sulfur (S) intensity through trace element analysis using X-ray fluorescence, quantifying monomers having sulfonate groups through gas chromatography mass spectrometry (GC / MS), or quantifying the sulfonate groups on the outermost surface of the resin microparticles through time-of-flight secondary ion mass spectrometry (TOF-SIMS) to qualitatively characterize the resin structure on the outermost surface of the resin microparticles.

[0057] <Other resins> The polyester resin emulsion for toner may contain other resins in addition to the polyester resin (A) as long as the effects of the present invention are not impaired. The other resins are not particularly limited and can be appropriately selected depending on the purpose. Examples of such other resins include homopolymers of styrene or its substituted derivatives such as polystyrene, poly-p-styrene, and polyvinyltoluene, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers, styrene-methacrylic acid copolymers, styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, styrene-butyl methacrylate copolymers, styrene-α-chloromethyl methacrylate copolymers, styrene-acrylonitrile copolymers, and styrene-vinylmethyl Examples of suitable resins include styrene copolymers such as ether copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isopropyl copolymers, and styrene-maleic acid ester copolymers; polymethyl methacrylate resins, polybutyl methacrylate resins, polyvinyl chloride resins, polyvinyl acetate resins, polyethylene resins, polyester resins, polyurethane resins, epoxy resins, polyvinyl butyral resins, polyacrylic acid resins, rosin resins, modified rosin resins, terpene resins, phenolic resins, aliphatic or aromatic hydrocarbon resins, aromatic petroleum resins, and resins thereof modified to have a functional group capable of reacting with an active hydrogen group such as an isocyanate group. These other resins may be used alone or in combination of two or more.

[0058] The solid content concentration in the polyester resin emulsion for toner is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5% by mass or more and 50% by mass or less, and more preferably 30% by mass or more and 45% by mass or less. When the solid content concentration in the polyester resin emulsion for toner is 5% by mass or more, the aggregation efficiency of the shell particles relative to the core particles is good, and the productivity of the toner is improved, which is preferable. When the solid content concentration in the polyester resin emulsion for toner is 50% by mass or less, the emulsion stability is favorable.

[0059] The method for measuring the solid content concentration of the polyester resin emulsion for toner is not particularly limited and can be appropriately selected depending on the purpose. For example, the solid content concentration can be calculated by drying an emulsion sample weighed on an aluminum cup in a thermostatic chamber set at 150°C for 3 hours, and then weighing the emulsion sample before and after drying.

[0060] Although details will be described later, the polyester resin emulsion for toner is preferably a shell resin emulsion used for producing a toner having a core-shell structure consisting of core particles containing a binder resin and shell particles covering the core particles.

[0061] [Method for producing polyester resin emulsion for toner] The method for producing the polyester resin emulsion for toner is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include shear emulsification, phase inversion emulsification, and other known dispersion methods. An example of the shear emulsification method is a method in which the polyester resin (A) is dissolved in an organic solvent, then added to an aqueous medium, and dispersed by mechanical shear force using a homomixer such as a low-speed shear type, high-speed shear type, friction type, high-pressure jet type, or ultrasonic type, a homogenizer, a ball mill with media, a sand mill, or a dyno mill. An example of the phase inversion emulsification method is a method in which the polyester resin (A) is dissolved in an organic solvent, and then an aqueous medium is added to cause phase inversion. Among these, the phase inversion emulsification method is preferred from the viewpoint of obtaining a homogeneous emulsion with a sharp particle size distribution.

[0062] <Phase inversion emulsification method> The phase inversion emulsification method is a method in which an aqueous medium is added to a resin solution obtained by dissolving the polyester resin (A) in an organic solvent, and then phase inversion emulsification is carried out.

[0063] - Organic solvents - The organic solvent used in the phase inversion emulsification method is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include ethanol, isopropanol, isobutanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, dibutyl ether, tetrahydrofuran, dioxane, methyl acetate, ethyl acetate, isopropyl acetate, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, and dichloroethylidene. Among these, methyl ethyl ketone, ethyl acetate, and isopropyl acetate are preferred from the viewpoints of solvent removability and polyester resin solubility. These may be used alone or in combination of two or more.

[0064] From the viewpoint of dispersion stability, it is preferable to quickly remove the organic solvent from the emulsion composed of the resin solution and the aqueous medium. The method for removing the organic solvent is not particularly limited, and a known desolvation method can be selected depending on the purpose. Examples include a method of gradually increasing the temperature of the emulsion while stirring to evaporate and remove the organic solvent from the system, a method of spraying the emulsion into a dry atmosphere such as air or nitrogen while stirring to remove the organic solvent from the system, and a method of reducing the pressure while stirring the emulsion to evaporate and remove the organic solvent from the system. These methods for removing the solvent may be used alone or in combination of two or more.

[0065] -Aqueous medium- The aqueous medium used in the phase inversion emulsification method is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include water and a mixture of water and an organic solvent miscible with water. The content of the aqueous medium is not particularly limited and can be appropriately selected depending on the purpose, and is preferably 80 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the resin solution. In the phase inversion emulsification method, the rate of addition of the aqueous medium until the resin solution undergoes phase inversion and is completed is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.1 to 60 parts by mass / min relative to 100 parts by mass of the resin solution, and more preferably 1 to 3 parts by mass / min. It is preferable that the rate of addition of the aqueous medium is 0.1 parts by mass / minute or more relative to 100 parts by mass of the resin solution, since this improves the productivity of the toner. When the addition rate of the aqueous medium is 60 mass parts / min or less per 100 mass parts of the resin solution, the particle size distribution becomes sharp and the cohesion of the shell particles relative to the core particles becomes good, which is preferable as it allows the shell layer to be formed uniformly.

[0066] In the phase inversion emulsification method, a neutralizing agent, a surfactant, a polymer protective colloid, etc. may be added to the resin solution or the aqueous medium within a range that does not impair the effects of the present invention.

[0067] -Neutralizer- The neutralizing agent is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include basic substances such as ammonia, trimethylamine, ethylamine, diethylamine, triethylamine, diethanolamine, triethanolamine, tributylamine, lithium hydroxide, sodium hydroxide, and potassium hydroxide. Among these, ammonia and sodium hydroxide are preferably used from the viewpoint of ensuring the quality of the emulsion.

[0068] The neutralization ratio (r), which is the molar ratio of the neutralizer to the acid value (AV) of the polyester resin (A), is not particularly limited and can be appropriately selected depending on the purpose. It is preferably 30% or more and 150% or less, and more preferably 60% or more and 100% or less. If the neutralization rate (r) is 30% or more, phase inversion emulsification proceeds easily, and an emulsion with a uniform particle size can be obtained, which is preferable. If the neutralization rate (r) is 150% or less, phase inversion emulsification is likely to proceed, which is preferable.

[0069] The amount of the neutralizing agent used is not particularly limited and can be appropriately selected depending on the purpose, and can be calculated, for example, by the following formula (1): where AV is the acid value of the resin (mg KOH / g), M is the amount of resin used (g), and r is the neutralization rate (%). Amount of neutralizing agent used (mol / g) = (AV / 56,110) × M × (r / 100) Equation (1)

[0070] -Surfactants- The surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include anionic surfactants such as alkylbenzenesulfonates, α-olefinsulfonates, and phosphate esters; amine salt-type cationic surfactants such as alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines; and quaternary ammonium salt-type cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride; nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives; and alanine, dodecyldi(aminoethyl)glycine, di(octylaminoethyl)glycine, and N-alkyl-N,N-dimethylammonium betaine.

[0071] -High polymer protective colloid- The polymer protective colloid is not particularly limited and can be appropriately selected depending on the purpose. Examples of the polymer protective colloid include acids such as acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and maleic anhydride; hydroxyl group-containing (meth)acrylic monomers such as β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerin monoacrylate, glycerin monomethacrylate, N-methylolacrylamide, and N-methylolmethacrylamide; vinyl alcohol; vinyl alcohols such as vinyl methyl ether, vinyl ethyl ether, and vinyl propyl ether. esters of vinyl alcohol and compounds containing a carboxyl group, such as vinyl acetate, vinyl propionate, and vinyl butyrate; acrylamide, methacrylamide, diacetone acrylamide, and methylol compounds thereof; acid chlorides, such as acrylic acid chloride and methacrylic acid chloride; homopolymers or copolymers of those having a nitrogen atom or a heterocyclic ring thereof, such as vinylpyridine, vinylpyrrolidone, vinylimidazole, and ethyleneimine; polyoxyethylene-based copolymers, such as polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, and polyoxyethylene nonylphenyl ester; and celluloses, such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0072] (Resin particles (T) and toner) The resin particles (T) of the present invention are resin particles (T) having a core-shell structure consisting of core particles containing a binder resin and shell particles covering the core particles, and the shell particles are formed from a polyester resin emulsion for toner, and may contain external additives and other components as necessary. The toner of the present invention has a core-shell structure consisting of core particles containing a binder resin and a shell that covers the core particles, and the shell is formed from a polyester resin emulsion for toners, and may contain external additives and other components as necessary. The "polyester resin emulsion for toner" is the same as that described in the above section (Polyester resin emulsion for toner), and therefore a detailed description thereof will be omitted. Furthermore, the resin particles (S) contained in the polyester resin emulsion for toner are different from the resin particles (T) made of the polyester resin emulsion for toner.

[0073] <Core-shell structure> The core-shell structure may be, for example, (1) a structure in which a shell particle made of a resin is disposed on the outermost surface of a core particle containing a binder resin, thereby coating the surface of the core particle, or (2) a structure in which a shell layer made of a resin is formed on the outermost surface of a core particle containing a binder resin, thereby coating the surface of the core particle. In the present invention, the term "shell layer" refers to a shell portion in which the structure (1) above is heat-treated so that the shell particles are fused together and the boundaries between the particles are no longer clear. The structure (2) is preferred from the viewpoints of achieving excellent toner homogeneity, heat-resistant storage stability, and mechanical durability, and of making the shell layer less likely to peel off due to stress. In the present invention, the shell portion in the core-shell structure of (1) and (2) above may be referred to as the "shell."

[0074] In the resin particles (T) and toner having the core-shell structure, the surface of the core particle does not need to be completely covered with the shell. However, from the viewpoints of toner homogeneity, heat-resistant storage stability, and mechanical durability, it is preferable that the covered area is 90% or more of the total surface area of the core particle.

[0075] <<Core particle>> The core particles contain a binder resin, and may contain, as necessary, a crystalline resin as a fixing aid, a coloring agent, a releasing agent, a charge control agent, and the like.

[0076] - Binder resin - The binder resin is not particularly limited and can be appropriately selected depending on the purpose. Examples of the binder resin include homopolymers of styrene or its substitution products such as polystyrene, poly-p-styrene, and polyvinyltoluene, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers, styrene-methacrylic acid copolymers, and styrene-methacrylic acid copolymers. styrene copolymers such as styrene-based copolymers such as methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer, and styrene-maleic acid ester copolymer; polymethyl methacrylate resin, polybutyl methacrylate resin, polyvinyl chloride resin, polyvinyl acetate resin, polyethylene resin, polyester resin, polyurethane resin, epoxy resin, polyvinyl butyral resin, polyacrylic acid resin, rosin resin, modified rosin resin, terpene resin, phenolic resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin, and these resins modified to have a functional group reactive with an active hydrogen group such as an isocyanate group. These may be used alone or in combination of two or more.

[0077] The binder resin preferably contains at least one amorphous polyester resin (B) from the viewpoint of improving the adhesion of the core particles to the shell particles and obtaining a toner having excellent mechanical durability. The polyester resin in the amorphous polyester resin (B) is not particularly limited and can be appropriately selected depending on the purpose. For example, the same polyester resins as those described in the above section <<Polyester Resin (A)>> can be used.

[0078] -Crystalline resin- The crystalline resin is not particularly limited as long as it has crystallinity and can be appropriately selected depending on the purpose, and examples thereof include polyester resin, polyurethane resin, polyurea resin, polyamide resin, polyether resin, vinyl resin, modified crystalline resin, etc. Among these, polyester resin is preferred from the viewpoint of achieving both excellent low-temperature fixability and heat-resistant storage stability. These may be used alone or in combination of two or more.

[0079] The crystalline resin is preferably one that melts at a temperature near the fixing temperature of the toner, and by including such a crystalline resin in the toner, the crystalline resin melts and becomes compatible with the binder resin at the fixing temperature, improving the sharp melting properties of the toner and exhibiting excellent low-temperature fixing properties. The melting point of the crystalline resin is not particularly limited, but is preferably 60° C. or higher and 100° C. or lower. When the melting point of the crystalline resin is 60° C. or higher, the crystalline resin is likely to melt at low temperatures, which is preferable because the heat-resistant storage stability of the toner is improved. If the melting point of the crystalline resin is 100° C. or less, the low-temperature fixability of the toner is favorable.

[0080] -Coloring agent- The colorant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the colorant include carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Balkan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, and anthrazan yellow BG. L, Isoindolinone Yellow, Bengala, Red Lead, Cinnabar, Cadmium Red, Cadmium Mercury Red, Antimony Vermilion, Permanent Red 4R, Para Red, Faise Red, Parachlor Orthonitroaniline Red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Lithol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine, Prussian Blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chromium Oxide, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake,Examples include malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc oxide, and lithopone. These may be used alone or in combination of two or more.

[0081] The content of the colorant is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1% by mass or more and 15% by mass or less, and more preferably 3% by mass or more and 10% by mass or less, based on the total amount of the resin particles (T) or the total amount of the toner. If the content of the colorant is 1% by mass or more relative to the total amount of the resin particles (T) or the total amount of the toner, the coloring power of the toner becomes good, which is suitable. When the content of the colorant is 15% by mass or less relative to the total amount of the resin particles (T) or the total amount of the toner, the pigment is well dispersed in the toner, and the coloring power and charging characteristics of the toner are good, which is preferable.

[0082] The colorant may be used as a masterbatch in which it is combined with a masterbatch resin. The masterbatch resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include polymers of styrene or substituted products thereof, styrene copolymers, polymethyl methacrylate resins, polybutyl methacrylate resins, polyvinyl chloride resins, polyvinyl acetate resins, polyethylene resins, polypropylene resins, polyester resins, epoxy resins, epoxy polyol resins, polyurethane resins, polyamide resins, polyvinyl butyral resins, polyacrylic acid resins, rosin, modified rosin, terpene resins, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffin, and paraffin. These may be used alone or in combination of two or more.

[0083] -Mold release agent- The release agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include alkanoic acid esters such as carnauba wax, rice wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, stearyl icosanoate, icosyl behenate, behenyl behenate, stearyl behenate, behenyl stearate, and stearyl stearate; polyalkanol esters such as tristearyl trimellitate and distearyl maleate; polyalkanoic acid amides such as dibehenylamide; polyalkylamides such as tristearyl trimellitate amide; dialkyl ketones such as distearyl ketone; polyolefin waxes such as polyethylene wax and polypropylene wax; and waxes such as long-chain hydrocarbons such as paraffin wax, microcrystalline wax, and sazol wax. Among these, alkanoic acid ester waxes are preferred. These may be used alone or in combination of two or more.

[0084] The melting point of the release agent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 40°C or higher and 160°C or lower, more preferably 50°C or higher and 120°C or lower, and even more preferably 60°C or higher and 90°C or lower. If the melting point of the release agent is 40° C. or higher, the heat-resistant storage stability is favorable. If the melting point of the release agent is 160° C. or less, the occurrence of cold offset during low-temperature fixing can be suppressed, which is preferable.

[0085] The content of the release agent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 15% by mass or less, and even more preferably 3% by mass or more and 7% by mass or less, based on the total amount of the resin particles (T) or the total amount of the toner. If the content of the release agent is 20% by mass or less based on the total amount of the resin particles (T) or the total amount of the toner, the fluidity of the toner is favorable.

[0086] -Charge control agent- The charge control agent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxyamines, quaternary ammonium salts, alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives.

[0087] The content of the charge control agent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, relative to 100 parts by mass of the resin particles (T) or 100 parts by mass of the toner. When the content of the charge control agent is 10 parts by mass or less relative to 100 parts by mass of the resin particles (T) or 100 parts by mass of the toner, the charging characteristics of the toner become good, and a decrease in the fluidity of the developer and a decrease in image density can be suppressed, which is preferable.

[0088] [Volume average particle diameter of core particles (Dv)] The volume average particle diameter (Dv) of the core particles is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of granularity, sharpness, and fine line reproducibility, it is preferable that the median diameter (D50) is 4 μm or more and 7 μm or less. The method for measuring the median diameter (D50) is not particularly limited and can be appropriately selected depending on the purpose. For example, the median diameter can be measured using a laser particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.).

[0089] [Average circularity of core particles] The average circularity of the core particles is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoints of transfer efficiency, fine line reproducibility, and cleaning properties of toner remaining on the photosensitive member or transfer belt, it is preferably 0.940 or more and 0.990 or less. The method for measuring the average circularity of the core particles is not particularly limited and can be appropriately selected depending on the purpose. For example, the measurement can be performed using a flow particle image analyzer FPIA-3000 (manufactured by SYSMEX Corporation).

[0090] The method for producing the core particles is not particularly limited and can be appropriately selected depending on the purpose. Examples include a kneading and grinding method and a so-called chemical method in which particles are granulated in an aqueous medium.

[0091] Examples of the chemical method include a suspension polymerization method, emulsion polymerization method, seed polymerization method, dispersion polymerization method, etc., which use a monomer as a starting material for production; a dissolution suspension method in which a resin or a resin precursor is dissolved in an organic solvent or the like and dispersed or emulsified in an aqueous medium; a phase inversion emulsification method in which water is added to a solution consisting of a resin or a resin precursor and a suitable emulsifier to invert the phase; and an aggregation method in which resin particles obtained by these methods are aggregated in a dispersed state in an aqueous medium and granulated into particles of a desired size by heating and melting, etc. Among these, the dissolution suspension method, phase inversion emulsification method, and aggregation method are preferred, as they allow easy handling of polyester resins that have excellent low-temperature fixability.

[0092] The core particles are preferably an aqueous dispersion from the viewpoint of aggregating with the polyester resin emulsion for toner, and more preferably an aqueous dispersion of core particles obtained by a chemical process.

[0093] When core particles obtained by the kneading and pulverization method are used, the core particles are preferably subjected to a spheroidizing treatment and a surface smoothing treatment such as heat treatment in order to form a uniform shell.

[0094] From the viewpoint of agglomerating the shell particles onto the surface of the core particles, it is preferable that the core particles are particles to which no external additives or flowability improvers have been added.

[0095] <<shell>> The shell can be obtained by a process in which a polyester resin emulsion made of the resin particles (S) is aggregated on the outermost surface of the core particles, and then heated and fused. The core particle and the shell are preferably in a state of being in close contact with each other, or in a state of not being completely compatible with each other, with a region consisting of only the core particle or the shell existing.

[0096] The average thickness of the shell is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 50 nm to 500 nm, more preferably 100 nm to 200 nm. When the average thickness of the shell is 50 nm or more, the function of the shell to protect the core particles is improved, and heat-resistant storage stability and mechanical durability are improved, which is preferable. If the average thickness of the shell is 500 nm or less, the low-temperature fixability is favorable.

[0097] The method for measuring the average shell thickness is not particularly limited and can be appropriately selected depending on the purpose. For example, the average shell thickness can be measured by cutting a sample in which toner particles are embedded in an epoxy resin or the like with a micromicrotome or an ultramicrotome, and examining the ultrathin sliced sample with a transmission electron microscope (TEM). In some cases, it may be preferable to stain the ultrathin sections with a staining agent such as ruthenium tetroxide or osmium tetroxide, as this makes the core-shell structure more visible. A sample of toner particles embedded in epoxy resin is cut into ultrathin slices using an ultramicrotome, and the cross-sectional images are photographed at 20,000x magnification using a TEM (field emission electron microscope JEM-2100F / JEOL).The photographed images are then imported into an image analyzer (LuzexAP / Nireco).The shell thickness is measured at five points on each of 30 toner particles, and the shell thickness can be calculated from the average value of these measurements.

[0098] The volume average particle diameter (Dv) of the resin particles (T) and the toner is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of obtaining a high-quality image excellent in granularity, sharpness, and fine line reproducibility, the volume average particle diameter (Dv) is preferably 3 μm or more and 10 μm or less, and more preferably 4 μm or more and 7 μm or less. If the volume average particle diameter (Dv) of the resin particles (T) and the toner is 3 μm or more, the fluidity and transferability of the toner are favorable.

[0099] The ratio (Dv / Dn) of the volume average particle diameter (Dv) of the resin particles (T) and the toner to the number average molecular weight (Dn) of the resin particles (T) and the toner represents the particle size distribution of the resin particles (T) and the toner, and the closer the value is to 1, the sharper the particle size distribution. From the viewpoints of sharpness and thin line reproducibility, the ratio (Dv / Dn) is preferably 1.20 or less, and more preferably 1.15 or less.

[0100] The method for measuring the volume average particle size (Dv) and number average molecular weight (Dn) of the resin particles (T) and the toner is not particularly limited, but can be measured using, for example, a Coulter Multisizer III (aperture diameter 100 μm) (manufactured by Beckman Coulter, Inc.).

[0101] The average circularity of the resin particles (T) and the toner is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.940 or more and 0.990 or less.More preferably, the average circularity of the resin particles (T) and the toner is 0.960 or more and 0.985 or less, and the content of the resin particles (T) and the toner having a circularity of less than 0.940 is 15% by mass or less based on the total amount of the resin particles (T) and the toner. Toners with an average circularity within the above range, i.e., substantially spherical, are effective for forming high-resolution images with excellent transfer efficiency, appropriate density, and reproducibility. They are also suitable because they can produce good images with few transfer defects in fine line images. This is thought to be because the toner surface is sufficiently smooth, reducing contact points with the image support and reducing transfer defects of the toner to the transfer material due to moth-like holes. When the average circularity of the resin particles (T) and the toner is 0.940 or more, they are suitable because they provide good transferability. When the average circularity of the resin particles (T) and the toner is 0.990 or less, in a system employing blade cleaning or the like, it is possible to solve the problem of poor cleaning on the photosensitive member, transfer belt, etc., causing stains on the image, which is preferable. For example, in development or transfer with a low image area ratio, there is little residual toner after transfer, and poor cleaning does not pose a particular problem. However, in the case of images with a high image area ratio, such as color photographic images, toner that has not been transferred due to poor paper feeding or the like may remain on the photosensitive member as residual toner after transfer, and if this accumulates, it will cause background smearing of the image. Furthermore, there is a problem that the charging roller that contact-charges the photosensitive member may also become contaminated, preventing it from exhibiting its original charging ability, but the present invention is advantageous in that it can solve this problem.

[0102] The method for measuring the average circularity of the resin particles (T) and the toner is not particularly limited and can be appropriately selected depending on the purpose. For example, the average circularity can be measured using a flow particle image analyzer FPIA-3000 (manufactured by SYSMEX Corporation). Specifically, the circularity is calculated from the two-dimensional image area of each particle captured by a CCD camera, and the circularity of each particle is added up and divided by the total number of particles. The circularity of each particle can be calculated by dividing the perimeter of a circle having the same projected area as the particle image by the perimeter of the particle projected image.

[0103] <External additives> The external additives are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include inorganic fine particles, polymeric fine particles, flow improvers, cleaning aids, and the like.

[0104] -Inorganic fine particles- Examples of the 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.

[0105] The primary particle diameter of the inorganic fine particles is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 nm or more and 2 μm or less, and more preferably 5 nm or more and 500 nm or less. The inorganic fine particles having a primary particle diameter of 5 nm or more are preferably able to suppress embedding in the toner particle surface due to mechanical stress, and the inorganic fine particles having a primary particle diameter of 2 μm or less are preferably able to suppress detachment from the toner particle. The specific surface area of the inorganic fine particles according to the BET method is 20 m 2 / g or more 500m 2 / g or less is preferred. The content of the inorganic fine particles is preferably 0.01% by mass or more and 5% by mass or less based on the total amount of the resin particles (T) and the toner.

[0106] -Polymer-based fine particles- Examples of the polymeric fine particles include polymer particles made of polycondensation systems such as polystyrene, methacrylate ester, acrylate ester copolymer, silicon, benzoguanamine, nylon, etc., obtained by soap-free emulsion polymerization, suspension polymerization, or dispersion polymerization, and polymer particles made of thermosetting resins.

[0107] -Flow improver- The flowability improver is not particularly limited and can be appropriately selected depending on the purpose as long as it can increase hydrophobicity by surface treatment and prevent deterioration of flow properties and charging properties even under high humidity, and examples thereof include silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils, etc. The inorganic fine particles of silica and titanium oxide are preferably surface-treated with the flowability improver and used as hydrophobic silica and hydrophobic titanium oxide.

[0108] -Cleaning aid- The cleaning aid is not particularly limited as long as it is added to the toner to remove the developer remaining on the photoreceptor or the primary transfer medium after transfer. Examples of the cleaning aid include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer fine particles produced by soap-free emulsion polymerization, such as polymethyl methacrylate fine particles and polystyrene fine particles. The polymer particles preferably have a relatively narrow particle size distribution, and the volume average particle size is preferably 0.01 μm or more and 1 μm or less.

[0109] The external additive is attached to the particle surfaces by the step of adding and mixing the external additive with the resin particles (T) and the toner. The mixing method is not particularly limited, and examples thereof include a method of applying an impact force to the mixture with blades rotating at high speed, a method of introducing the mixture into a high-speed air current, accelerating it, and causing the particles or composite particles to collide with an appropriate collision plate, etc. Specific examples of the mixing means include an Ang Mill (manufactured by Hosokawa Micron Corporation), a modified I-type Mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) with reduced pulverizing air pressure, a Hybridization System (manufactured by Nara Machinery Works), a Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), and an automatic mortar.

[0110] [Method for producing resin particles (T) having a core-shell structure and toner] The method for producing the resin particles (T) and the toner is not particularly limited, but may include, for example, an aggregation step and a fusion step, and may also include a washing step, a drying step, and an annealing step, as necessary.

[0111] <Agglomeration process> The aggregation step is a step in which shell particles are added to a dispersion of core particles dispersed in an aqueous medium, and the shell resin is aggregated on the surfaces of the core particles while stirring.

[0112] The aggregation step may be carried out under heating. The temperature of the aqueous medium in the aggregation step is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of efficient aggregation, however, it is preferably 20°C or higher and the glass transition temperature (Tg) of the polyester resin (A) or lower.

[0113] In the aggregation step, from the viewpoint of promoting aggregation, an aggregating agent may be added or the pH may be adjusted. The flocculant is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include aluminum chloride, zinc sulfate, magnesium sulfate, aluminum sulfate, potassium aluminum sulfate, sodium chloride, sodium bromide, sodium iodide, sodium fluoride, sodium acetate, sodium acetoacetate, lithium chloride, lithium bromide, lithium iodide, lithium fluoride, lithium acetate, lithium acetoacetate, potassium chloride, potassium bromide, potassium iodide, potassium fluoride, potassium acetoacetate, magnesium bromide, magnesium chloride, magnesium iodide, and magnesium fluoride. Examples of the iron ore include magnesium, magnesium acetate, magnesium acetoacetate, calcium chloride, calcium bromide, barium bromide, barium chloride, barium iodide, barium fluoride, barium acetate, barium acetoacetate, strontium bromide, strontium chloride, strontium iodide, strontium fluoride, strontium acetate, strontium acetoacetate, zinc bromide, zinc chloride, zinc iodide, zinc fluoride, zinc acetate, zinc acetoacetate, copper bromide, copper chloride, copper iodide, copper fluoride, copper acetate, copper acetoacetate, iron bromide, iron chloride, iron iodide, iron fluoride, iron acetate, and iron acetoacetate. These may be used alone or in combination of two or more.

[0114] The content of the aggregating agent is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.1 parts by mass or more and 20 parts by mass or less, and more preferably 0.5 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the total amount of the core particles and the shell particles. The flocculant is preferably used as an aqueous solution from the viewpoint of uniform flocculation in the reaction system. When the flocculant is used as an aqueous solution, the content of the flocculant is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, based on the total amount of the aqueous solution.

[0115] The rate at which the aggregates are added to the aqueous medium is not particularly limited and can be appropriately selected depending on the purpose. The rate is preferably 0.1 parts by mass or more and 5 parts by mass or less, and more preferably 0.5 parts by mass or more and 2 parts by mass or less, per 100 parts by mass of the aqueous medium containing the core particles and the shell particles.

[0116] The aggregation reaction in the aggregation step can be terminated as needed by any method, including, but not limited to, adding a salt with a low ionic valence, a chelating agent, a surfactant, or the like, adjusting the pH, lowering the temperature of the dispersion, or adding a large amount of an aqueous medium to dilute the concentration. Examples of the chelating agent include metal salts such as sodium ethylenediaminetetraacetate, sodium gluconate, sodium tartrate, sodium citrate, potassium citrate, and nitrotriacetate salts, and polymer electrolytes.

[0117] <Fusing process> The fusion step is a step of heat-fusion bonding the aggregated particles, which are composed of core particles and shell particles obtained in the aggregation step, to form shells on the surfaces of the core particles.

[0118] In the fusion step, the dispersion of the aggregated particles is preferably heated while being stirred. The temperature in the fusion step is not particularly limited, but is preferably equal to or higher than the glass transition temperature (Tg) of the polyester resin (A).

[0119] <Cleaning process> The washing step is a step of washing the resin particles (T) and toner obtained in the fusion step. The washing method in the washing step is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include centrifugation, vacuum filtration, and filter press. If the washing is not sufficient in one operation, the cake obtained in the washing step may be dispersed again in an aqueous solvent to form a slurry, and the step of extracting the resin particles (T) and the toner by any of the above methods may be repeated. In addition, when washing is performed by vacuum filtration or filter press, the washing method may be performed by passing the aqueous solvent through the cake. The aqueous solvent used for the washing is not particularly limited, and examples thereof include water and mixed solvents obtained by mixing water with alcohols such as methanol and ethanol. Among these, water is preferred from the viewpoints of cost and environmental load due to wastewater treatment.

[0120] <Drying process> The drying step is a step of drying the cake obtained in the washing step. The drying method in the drying step is not particularly limited and may be appropriately selected depending on the purpose. Examples of the drying method include a method using a dryer such as a spray dryer, a vacuum freeze dryer, a reduced pressure dryer, a stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, a rotary dryer, or an agitator dryer. The drying is preferably carried out until the moisture content in the cake becomes less than 1%. The resin particles (T) and toner obtained after drying may be crushed using a device such as a jet mill, a Henschel mixer, a super mixer, a coffee mill, an Oster blender, or a food processor to break up aggregates.

[0121] <Annealing> The annealing is preferably carried out when the core particles contain the crystalline polyester resin. The annealing temperature is preferably equal to or higher than the glass transition temperature and equal to or lower than the melting point of the crystalline polyester resin, and the annealing time is preferably 3 hours to 24 hours, more preferably 6 hours to 15 hours.

[0122] <Developer> The toner of the present invention can be used as a developer containing other components such as a carrier, which are appropriately selected. The developer may be a one-component developer or a two-component developer, but when used in high-speed printers that correspond to the recent improvements in information processing speed, a two-component developer is preferred because it has a longer life. In the case of a one-component developer using the above toner, even if there is a toner balance, i.e., even if toner is supplied to the developer and consumed by development, there is little fluctuation in the particle size of the toner, and there is no toner filming on the developing roller or toner fusion to layer thickness regulating members such as blades for thinning the toner layer, and good and stable developability and images can be obtained even with long-term use (stirring) of the developing means. In the case of the two-component developer using the toner, even if the toner is balanced over a long period of time, there is little fluctuation in the toner particle size in the developer, and good and stable developability can be obtained even with long-term stirring in the developing means.

[0123] The carrier is not particularly limited and can be appropriately selected depending on the purpose, but is preferably one having a core material and a resin layer covering the core material. The material for the core is not particularly limited and can be appropriately selected depending on the purpose. For example, manganese-strontium (Mn-Sr)-based materials and manganese-magnesium (Mn-Mg)-based materials with a magnetic field of 50 emu / g to 90 emu / g are preferred. From the viewpoint of ensuring image density, highly magnetic materials such as iron powder (100 emu / g or more) and magnetite (75 emu / g to 120 emu / g) are preferred. Furthermore, weakly magnetic materials such as copper-zinc (Cu-Zn)-based materials (30 emu / g to 80 emu / g) are preferred because they can weaken the contact of the toner with the electrostatic latent image carrier in a standing state, which is advantageous for achieving high image quality. These may be used alone or in combination of two or more.

[0124] The particle size of the core material is preferably 10 μm or more and 200 μm or less, and more preferably 40 μm or more and 100 μm or less, in terms of average particle size (weight average particle size (D50)). When the average particle size (weight average particle size (D50)) is 10 μm or more, the distribution of carrier particles contains a large amount of fine powder, which is advantageous in that it can solve the problem of carrier scattering due to low magnetization per particle. If the average particle size (weight average particle size (D50)) is 200 μm or less, the specific surface area decreases, causing toner scattering, which is advantageous in that it can solve the problem of poor reproduction of solid areas, especially in full color toners with many solid areas.

[0125] The material of the resin layer is not particularly limited and can be appropriately selected from known resins depending on the purpose, and examples thereof include amino resins, polyvinyl resins, polystyrene resins, halogenated olefin resins, polyester resins, polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytrifluoroethylene resins, polyhexafluoropropylene resins, copolymers of vinylidene fluoride and an acrylic monomer, copolymers of vinylidene fluoride and vinyl fluoride, fluoroterpolymers (fluorinated triple (multi) copolymers) such as terpolymers of tetrafluoroethylene, vinylidene fluoride and a non-fluorinated monomer, and silicone resins. Among these, silicone resins are preferred. These may be used alone or in combination of two or more.

[0126] The silicone resin is not particularly limited and can be appropriately selected from commonly known silicone resins depending on the purpose. Examples include straight silicone resins consisting only of organosiloxane bonds, and silicone resins modified with alkyd resins, polyester resins, epoxy resins, acrylic resins, urethane resins, etc. The silicone resin may be a synthetic resin or a commercially available product, such as straight silicone resins KR271, KR255, and KR152 manufactured by Shin-Etsu Chemical Co., Ltd., and SR2400, SR2406, and SR2410 manufactured by Dow Corning Toray Silicones Co., Ltd.

[0127] The modified silicone resin may be suitably synthesized or may be a commercially available product, such as KR206 (alkyd-modified), KR5208 (acrylic-modified), ES1001N (epoxy-modified), or KR305 (urethane-modified), all of which are manufactured by Shin-Etsu Chemical Co., Ltd., and SR2115 (epoxy-modified) and SR2110 (alkyd-modified), all of which are manufactured by Dow Corning Toray Silicones Co., Ltd.

[0128] The silicone resin may be used alone, or may be used together with a crosslinking component, a charge amount adjusting component, etc.

[0129] The resin layer may contain conductive powder or the like as needed. Examples of the conductive powder include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide. The average particle size of the conductive powder is preferably 1 μm or less, from the viewpoint of facilitating control of electrical resistance.

[0130] The resin layer can be formed, for example, by dissolving the silicone resin or the like in a solvent to prepare a coating solution, then uniformly coating the coating solution on the surface of the core material by a known coating method, drying, and then baking. Examples of the coating method include a dipping method, a spraying method, and a brush coating method. The solvent is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cellosolve, and butyl acetate. The baking method is not particularly limited, and may be an external heating method or an internal heating method, such as a method using a fixed electric furnace, a fluidized electric furnace, a rotary electric furnace, a burner furnace, or the like, or a method using microwaves.

[0131] The content of the carrier is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.01% by mass or more and 5.0% by mass or less with respect to the total amount of the resin layer. If the content of the carrier is 0.01% by mass or more relative to the total amount of the resin layer, a uniform resin layer can be formed on the surface of the core material, which is preferable. If the content of the carrier is 5.0% by mass or less relative to the total amount of the resin layer, the thickness of the resin layer increases, and the carrier particles granulate together, which makes it difficult to obtain uniform carrier particles. This is preferable.

[0132] When the developer is a two-component developer, the content of the carrier is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 90% by mass or more and 98% by mass or less, and more preferably 93% by mass or more and 97% by mass or less, of the total amount of the two-component developer. The mixing ratio of the toner and the carrier in the two-component developer is preferably 1 part by mass or more and 10.0 parts by mass or less of the toner to 100 parts by mass of the carrier.

[0133] [Image forming apparatus and image forming method] The image forming apparatus according to the present invention is not particularly limited and can be appropriately selected depending on the purpose as long as it uses the toner of the present invention, and examples thereof include an apparatus having an electrostatic latent image carrier, an electrostatic latent image forming means, a developing means, and optionally other means. The image forming method according to the present invention is not particularly limited and can be appropriately selected depending on the purpose as long as it uses the toner of the present invention, and examples thereof include an apparatus having an electrostatic latent image forming step and a developing step, and optionally other steps.

[0134] <Electrostatic latent image carrier> The latent image carrier is not particularly limited in terms of material, shape, structure, size, etc., and can be appropriately selected from known ones. A preferred shape is a drum, and examples of the material include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors such as polysilane and phthalopolymethine. Examples of the organic photoreceptor include a laminated photoreceptor having a laminated structure in which a layer (charge generation layer) in which a charge generation material such as metal-free phthalocyanine or titanyl phthalocyanine is dispersed in a binder resin and a layer (charge transport layer) in which a charge transport material is dispersed in a binder resin are stacked on a support such as an aluminum drum, and a single-layer photoreceptor having a single-layer photosensitive layer in which both a charge generation material and a charge transport material are dispersed in a binder resin on a support. In the single-layer photoreceptor, a hole transport material and an electron transport material can also be added to the photosensitive layer as charge transport materials. An undercoat layer may be provided between the support and the multilayer charge generating layer or the single-layer photosensitive layer. The linear speed of the electrostatic latent image bearing member is preferably 300 mm / s or more.

[0135] <Electrostatic latent image forming means and electrostatic latent image forming process> The electrostatic latent image forming means is not particularly limited as long as it is a means for forming an electrostatic latent image on the electrostatic latent image carrier, and can be appropriately selected depending on the purpose. For example, it may be a means having at least a charging member that charges the surface of the electrostatic latent image carrier, and an exposure member that exposes the surface of the electrostatic latent image carrier to light in an imagewise manner. The electrostatic latent image forming step is not particularly limited as long as it is a step of forming an electrostatic latent image on the electrostatic latent image bearing member, and can be appropriately selected depending on the purpose. For example, the electrostatic latent image forming step can be performed by charging the surface of the electrostatic latent image bearing member and then exposing it to light in an imagewise manner, using the electrostatic latent image forming unit.

[0136] <<Charging materials and charging>> The charging member is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include known contact chargers equipped with a conductive or semiconductive roller, brush, film, rubber blade, etc., and non-contact chargers utilizing corona discharge such as corotrons and scorotrons, etc. Among these, it is preferable to use a contact-type charging member, since this allows for an image forming apparatus in which the amount of ozone generated from the charging member is reduced. The shape of the charging member may be a roller, a magnetic brush, a fur brush, or any other shape, and can be selected according to the specifications and shape of the image forming apparatus.

[0137] The charging can be carried out, for example, by applying a voltage to the surface of the electrostatic latent image bearing member using the charging member.

[0138] <<Exposure member and exposure>> The exposure member is not particularly limited as long as it can expose the surface of the electrostatic latent image carrier charged by the charging member in the shape of an image to be formed, and can be appropriately selected depending on the purpose. Examples of the exposure member include various exposure members such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system.

[0139] The light source used in the exposure member is not particularly limited and can be appropriately selected depending on the purpose. Examples include general light-emitting materials such as fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light-emitting diodes (LEDs), semiconductor lasers (LDs), and electroluminescence (EL). In addition, the light source used in the exposure member uses various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter in order to irradiate only light in a desired wavelength range. It is also possible.

[0140] The exposure can be carried out, for example, by exposing the surface of the electrostatic latent image bearing member to light in an imagewise manner using the exposure member. In the present invention, a backlight system may be employed in which exposure is performed imagewise from the back side of the electrostatic latent image bearing member.

[0141] <Developing means and developing process> The developing unit is not particularly limited as long as it is a developing unit that has a toner that develops the electrostatic latent image formed on the electrostatic latent image carrier to form a toner image that is a visible image, and can be appropriately selected depending on the purpose. The developing step is not particularly limited as long as it is a step of forming a toner image, which is a visible image, by developing the electrostatic latent image formed on the electrostatic latent image carrier with a toner, and can be appropriately selected depending on the purpose. For example, the developing step can be performed by the developing unit. The developing means is preferably a developing device having an agitator that frictionally agitates the toner to charge it, a magnetic field generating means fixed inside, and a rotatable developer carrier that carries a developer containing the toner on its surface.

[0142] <Other means and other steps> Examples of the other means include a transfer means, a fixing means, a cleaning means, a discharging means, and a recycling means. Examples of the other steps include a transfer step, a fixing step, a cleaning step, a charge removal step, and a recycling step.

[0143] <<Transfer means and transfer process>> The transfer means is not particularly limited as long as it is a means for transferring a visible image onto a recording medium, and can be selected appropriately depending on the purpose. However, a preferred embodiment has a primary transfer means for transferring the visible image onto an intermediate transfer body to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. The transfer step is not particularly limited as long as it is a step of transferring a visible image onto a recording medium, and can be appropriately selected depending on the purpose. However, a preferred embodiment is one in which an intermediate transfer body is used, a visible image is primarily transferred onto the intermediate transfer body, and then the visible image is secondarily transferred onto a recording medium. The transfer step can be carried out by, for example, charging the visible image on the photosensitive member using a transfer charger, and can be carried out by the transfer unit.

[0144] Here, when the image to be secondarily transferred onto the recording medium is a color image made up of toners of multiple colors, the transfer means can be configured to sequentially overlay toners of each color on the intermediate transfer body to form an image on the intermediate transfer body, and the intermediate transfer means can secondarily transfer the image on the intermediate transfer body onto the recording medium all at once. The intermediate transfer member is not particularly limited and can be appropriately selected from known transfer members depending on the purpose, and a suitable example is a transfer belt.

[0145] The transfer means (the primary transfer means and the secondary transfer means) preferably has at least a transfer device that peels and charges the visible image formed on the photosensitive member onto the recording medium. I wish. Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device. The recording medium is typically plain paper, but is not particularly limited as long as it is capable of transferring an unfixed image after development, and can be selected appropriately depending on the purpose. For example, a PET base for an OHP can also be used.

[0146] <<Fixing means and fixing process>> The fixing means is not particularly limited as long as it is a means for fixing the transferred image transferred onto the recording medium, and can be appropriately selected depending on the purpose. For example, a known heating and pressing member is preferred. Examples of the heating and pressing member include a combination of a heating roller and a pressure roller, and a combination of a heating roller, a pressure roller and an endless belt. The fixing step is not particularly limited as long as it is a step of fixing the visible image transferred to the recording medium, and can be appropriately selected depending on the purpose. For example, the fixing step may be performed for each color toner transferred to the recording medium, or may be performed simultaneously for each color toner in a stacked state. The fixing step can be performed by the fixing unit. The heating temperature in the heating and pressing member is preferably 80°C to 200°C.

[0147] In the present invention, depending on the purpose, a known optical fixing device may be used together with or instead of the fixing means. The surface pressure in the fixing step is not particularly limited and can be appropriately selected depending on the purpose. 2 ~80N / cm 2 It is preferable that:

[0148] <<Cleaning means and cleaning process>> The cleaning means is not particularly limited as long as it can remove the toner remaining on the photosensitive member, and can be appropriately selected depending on the purpose. Examples of the cleaning means include a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, a brush cleaner, and a web cleaner. The cleaning step is not particularly limited as long as it can remove the toner remaining on the photoreceptor, and can be appropriately selected depending on the purpose. For example, the cleaning step can be performed by the cleaning unit.

[0149] <<Static removal means and static removal process>> The discharging means is not particularly limited as long as it is a means for discharging the photosensitive member by applying a discharging bias to the photosensitive member, and can be appropriately selected depending on the purpose. For example, a discharging lamp can be used. The charge-eliminating step is not particularly limited as long as it is a step of applying a charge-eliminating bias to the photosensitive member to eliminate charges, and can be appropriately selected depending on the purpose. For example, it can be performed by the charge-eliminating unit.

[0150] <<Recycling methods and processes>> The recycling means is not particularly limited as long as it is a means for recycling the toner removed by the cleaning step into the developing device, and can be appropriately selected depending on the purpose. For example, known conveying means can be used. The recycling step is not particularly limited as long as it is a step of recycling the toner removed by the cleaning step into the developing device, and can be appropriately selected depending on the purpose. For example, it can be performed by the recycling means.

[0151] Here, an image forming apparatus according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments, and other modifications, additions, corrections, deletions, and other changes can be made within the scope of what one skilled in the art can conceive. Any embodiment is within the scope of the present invention as long as it achieves the functions and effects of the present invention.

[0152] One embodiment of a method for forming an image using an image forming apparatus of the present invention will be described with reference to Fig. 1. Although a printer is shown as an example of the image forming apparatus of this embodiment, the image forming apparatus of the present invention is not particularly limited as long as it is capable of forming an image using toner in a copier, facsimile, multifunction machine, or the like.

[0153] 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention, which includes a paper feed unit 210, a conveyance unit 220, an image forming unit 230, a transfer unit 240, and a fixing unit 250. The paper feed section 210 includes a paper feed cassette 211 in which paper sheets P to be fed are stacked, and a paper feed roller 212 that feeds the paper sheets P stacked in the paper feed cassette 211 one by one.

[0154] The conveying section 220 includes a roller 221 that conveys the paper P fed by the paper feed roller 212 toward the transfer section 240, a pair of timing rollers 222 that hold the leading end of the paper P conveyed by the roller 221 and wait, sending the paper to the transfer section 240 at a predetermined timing, and a paper discharge roller 223 that discharges the paper P with the fixed color toner image onto a paper discharge tray 224.

[0155] The image forming section 230 includes, at predetermined intervals from left to right in FIG. 1, an image forming unit 180Y that forms an image using a developer containing yellow toner, an image forming unit 180C that uses a developer containing cyan toner, an image forming unit 180M that uses a developer containing magenta toner, an image forming unit 180K that uses a developer containing black toner, and an exposure device 233.

[0156] The image forming unit 180 (180Y, 180C, 180M, 180K) is arranged to be rotatable clockwise in FIG. 1, and includes a photosensitive drum 231 (231Y, 231C, 231M, 231K) on which an electrostatic latent image and a toner image are formed, chargers 232 (232Y, 232C, 232M, 232K) that uniformly charge the surface of the photosensitive drum 231 (231Y, 231C, 231M, 231K), and cleaners 236 (236Y, 236C, 236M, 236K) that remove toner remaining on the surface of the photosensitive drum 231 (231Y, 231C, 231M, 231K).

[0157] The image forming units 180 (180Y, 180C, 180M, 180K) are equipped with toner bottles 234 (234Y, 234C, 234M, 234K) that contain toner of each color, and sub-hoppers 160 (160Y, 160C, 160M, 160K) that replenish the toner supplied from the toner bottles 234 (234Y, 234C, 234M, 234K).

[0158] It should be noted that when referring to any one of the image forming units 180 (180Y, 180C, 180M, 180K), it will be referred to as the image forming unit.

[0159] The exposure device 233 irradiates the photosensitive drum 231 with laser light L emitted from a light source 233a based on image information, by reflecting the light on a polygon mirror 233b (233bY, 233bC, 233bM, 233bK) that is driven to rotate by a motor. The developer contains toner and carrier. The four image forming units 180 (180Y, 180C, 180M, 180K) have substantially the same mechanical configuration, except for the developer used therein.

[0160] The transfer unit 240 includes a drive roller 241 and a driven roller 242, an intermediate transfer belt 243 that can rotate counterclockwise in Figure 1 as the drive roller 241 is driven, primary transfer rollers 244 (244Y, 244C, 244M, 244K) that are arranged opposite the photosensitive drums 231 (231Y, 231C, 231M, 231K) across the intermediate transfer belt 243, and secondary opposing rollers 245 and 246 that are arranged opposite each other across the intermediate transfer belt 243 at the position where the toner image is transferred to the paper.

[0161] The fixing device 250 has a heater installed inside and is equipped with a fixing belt 251 that heats the paper P, and a pressure roller 252 that forms a nip by rotatably applying pressure to the fixing belt 251. This applies heat and pressure to the color toner image on the paper P, and the color toner image is fixed. The paper P on which the color toner image has been fixed is discharged onto a paper discharge tray 224 by a paper discharge roller 223, completing a series of image forming processes. [Example]

[0162] Examples and comparative examples of the present invention will be described below, but the present invention is not limited to these examples in any way.

[0163] The present invention will be specifically explained below with reference to Production Examples, Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to these Production Examples, Synthesis Examples, Preparation Examples, and Examples. In the Production Examples, Synthesis Examples, Preparation Examples, Examples, and Comparative Examples, unless otherwise specified, "%" indicates "% by mass" and "parts" indicates "parts by mass." Furthermore, the blending amounts in the Examples and Comparative Examples indicate the blending amounts of solids in each raw material.

[0164] First, each measurement method will be described.

[0165] (Production Example 1: Production example of polyester resin for shell) [Production of polyester resins SR1 to SR41 for shells] A reactor equipped with a condenser, a stirrer, and a nitrogen inlet tube was charged with the acid monomers and alcohol monomers shown in Table 4 so that the hydroxyl group-to-carboxylic acid molar ratio (OH / COOH) was 1.2. Tetrabutoxy titanate (1,000 ppm relative to the total monomer amount) was also added as a condensation catalyst. The mixture was heated to 200°C over 2 hours under a nitrogen stream, then further heated to 230°C over 8 hours, and reacted for 5 hours while distilling off the resulting water. The mixture was then reacted for 1 hour under a reduced pressure of 5 to 15 mmHg. After cooling to 200°C, trimellitic anhydride (as shown in Tables 1-1 to 1-4) was added and reacted at 200°C under normal pressure for 1 hour. The mixture was then further reacted under a reduced pressure of 5 to 20 mmHg until the desired molecular weight was reached, yielding [shell polyester resins SR1 to SR41].

[0166] <<Measurement of Glass Transition Temperature of Polyester Resin for Shell>> The glass transition temperatures (Tg) of the [shell polyester resins SR1 to SR41] obtained in the above Production Examples were measured using a DSC system (differential scanning calorimeter) (Q-200, manufactured by TA Instruments) by the following method. First, approximately 5.0 mg of [shell polyester resins SR1 to SR41] was placed in an aluminum sample container, which was then placed on a holder unit and placed in an electric furnace. Next, under a nitrogen atmosphere, the sample was heated from -80°C to 150°C at a heating rate of 10°C / min (first heating). The sample was then cooled from 150°C to -80°C at a cooling rate of 10°C / min, and further heated to 150°C at a heating rate of 10°C / min (second heating). During each of the first and second heatings, a DSC curve was measured using a differential scanning calorimeter (Q-200, manufactured by TA Instruments). From the obtained DSC curves, the DSC curve at the second temperature rise was selected using the analysis program in the Q-200 system, and the glass transition temperatures at the second temperature rise of [shell polyester resins SR1 to SR41] were determined, and these were taken as the glass transition temperatures (Tg) of [shell polyester resins SR1 to SR41].

[0167] <<Acid value of polyester resin for shell>> The acid values of the [shell polyester resins SR1 to SR41] obtained in the above Production Examples were measured under the following conditions in accordance with the measurement method described in JIS K0070-1992. 0.5 g of each resin (0.3 g of the ethyl acetate soluble portion) was added to 120 mL of toluene and dissolved by stirring at room temperature (23°C) for about 10 hours. Further, 30 mL of ethanol was added to prepare a sample solution. The acid value of the sample solution was measured at 23°C using an automatic potentiometric titrator (DL-53 Titrator, Mettler-Toledo) and an electrode DG113-SC (Mettler-Toledo), and the results were analyzed using the analytical software LabX Light Version 1.00.000. A mixed solvent of 120 mL of toluene and 30 mL of ethanol was used in the apparatus. The measurement can be carried out by the above-mentioned measurement method, but specifically, the acid value was calculated as follows: Titration was carried out in advance with a standardized 0.1 N potassium hydroxide / alcohol solution, and the acid value was calculated from the titration amount using the following formula. Acid value [mgKOH / g] = titration amount [mL] × N × 56.1 [mg / mL] / sample mass [g] (In the above formula, "N" represents the factor of a 0.1N potassium hydroxide / alcohol solution.)

[0168] <<Hydroxyl value of polyester resin for shell>> The hydroxyl values (OHV) of the [shell polyester resins SR1 to SR41] obtained in the above Production Examples were measured under the following conditions in accordance with the measurement method described in JIS K0070-1992. Place 25 g of acetic anhydride in a 100 mL volumetric flask, add pyridine to bring the total volume to 100 mL, and shake thoroughly to prepare the acetyl reagent. Weigh 2 g of resin into a 200 mL flat-bottom flask and add 5 mL of the acetylation reagent using a pipette. Attach an air condenser to the neck of the flat-bottom flask and immerse approximately 1 cm of the bottom in a glycerin bath at 95-100°C for heating. After 1 hour, remove the flat-bottom flask from the bath and allow it to cool. Then, add 1 mL of water from the top of the air condenser and shake to decompose the acetic anhydride. To further complete the decomposition, heat it again in the glycerin bath for 10 minutes, allow it to cool, and then wash the air condenser with 5 mL of ethanol. 100 mL of ethanol was added as a solvent to the flat-bottom flask to prepare a measurement sample solution. The hydroxyl value of the sample solution was measured at 23°C using an automatic potentiometric titrator (DL-53 Titrator, Mettler-Toledo) and an electrode DG113-SC (Mettler-Toledo), and the results were analyzed using the analytical software LabX Light Version 1.00.000. Tetrahydrofuran (THF) was used as the solvent for the measurements. The measurement can be carried out by the above-mentioned measurement method, but specifically, the hydroxyl value was calculated as follows: Titration was carried out in advance with a standardized 0.1 N potassium hydroxide / alanol solution, and the hydroxyl value was calculated from the titration amount using the following formula. Hydroxyl value [mgKOH / g] = (Titer volume of blank titration [mL] - Titer volume [mL]) × N × 28.05 / Sample mass [g] + A (In the above formula, "N" represents the factor of the 0.1N potassium hydroxide / alcohol solution, and "A" represents the acid value of the resin.)

[0169] The obtained [shell polyester resins SR1 to SR41] were measured for glass transition temperature (Tg), weight average molecular weight, acid value (AV), and hydroxyl value (OHV), and the results are shown in Tables 1-1 to 1-4.

[0170] (Production Example 2: Production Example of Amorphous Polyester Resin for Core) [Production of amorphous polyester resin A1] Into a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube, a diol component consisting of a 2-mol ethylene oxide adduct of bisphenol A and a 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 % of trimethylolpropane relative to the total monomer amount were added so that the molar ratio of hydroxyl groups to carboxylic acids (OH / COOH) was 1.2. Furthermore, tetrabutyl orthotitanate was added as a condensation catalyst to a concentration of 1,000 ppm relative to the total monomer amount, and the mixture was heated to 230°C over 2 hours under a nitrogen stream and reacted for 5 hours while distilling off the generated water. The mixture was then reacted for 4 hours under a reduced pressure of 5 to 15 mmHg, cooled to 180°C, and then 1.0 mol% of trimellitic anhydride relative to the total monomer amount and 200 ppm of tetrabutyl orthotitanate relative to the total monomer amount were added. The mixture was reacted at 180°C under normal pressure for 1 hour, and then further reacted for 3 hours under a reduced pressure of 5 to 20 mmHg. Amorphous polyester resin A1 was obtained, which had a glass transition temperature (Tg) of 57°C, a weight-average molecular weight of 7,700, and an acid value of 18 mgKOH / g, as determined from the DSC curve of the first heating run.

[0171] <<Measurement of the glass transition temperature of amorphous polyester resin A1>> The glass transition temperature of the amorphous polyester resin A1 was measured by the same method as that for the resins SR1 to SR41 for the polyester resin emulsion.

[0172] <<Measurement of molecular weight of amorphous polyester resin A1>> The molecular weight of the [amorphous polyester resin A1] was measured by dissolving the [amorphous polyester resin A1] in tetrahydrofuran (THF) (containing a stabilizer, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) or chloroform at 0.15% by mass, filtering the solution through a 0.2 μm filter, and using the filtrate as a sample, using a gel permeation chromatograph (GPC) measuring device under the following analytical conditions. [Analysis conditions] Gel permeation chromatograph (GPC) measuring device: GPC-8220GPC (Tosoh Corporation) Column: TSKgel (registered trademark) SuperHZM-H 15 cm, triple column (manufactured by Tosoh Corporation) ·Temperature: 40℃ Detector: RI (refractive index) detector Solvent: tetrahydrofuran (THF) or chloroform Flow rate: 0.35 mL / min Sample: 100 μL of 0.15% by mass sample injected The molecular weight distribution of the sample was calculated from the relationship between the logarithm of the calibration curve and the count number, which was prepared using several monodisperse polystyrene standard samples. The standard polystyrene samples used for preparing the calibration curve were Showdex (registered trademark) STANDARD (manufactured by Showa Denko K.K.), Std. Nos. S-6550, S-1700, S-740, S-321, S-129, S-10, S-2.9, and S-0.6.

[0173] <<Measurement of the acid value of amorphous polyester resin A1>> The acid value of the [amorphous polyester resin A1] was measured in the same manner as in the resins SR1 to SR41 for the polyester resin emulsion.

[0174] (Production Example 3: Synthesis of Crystalline Polyester Resin C-1) 1,6-hexanediol and sebacic acid were charged into a 5 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple so that the ratio of OH groups to COOH groups (OH / COOH) was 1.1. The mixture was reacted with 500 ppm of titanium tetraisopropoxide (based on the mass of the charged raw materials) while water was being discharged. The temperature was finally raised to 235°C and the reaction was continued for 1 hour. The reaction was then continued for 6 hours under reduced pressure of 10 mmHg or less. Thereafter, the temperature was set to 185° C., trimellitic anhydride was added so that the molar ratio to the COOH groups was 0.053, and the mixture was allowed to react for 2 hours with stirring to obtain [Crystalline Polyester Resin C-1].

[0175] A four-neck flask was charged with 55 parts of crystalline polyester resin C-1, 35 parts of methyl ethyl ketone, and 10 parts of 2-propyl alcohol. The mixture was then heated and stirred at the melting point of the crystalline polyester resin C-1 to dissolve the crystalline polyester resin, thereby obtaining a solution.

[0176] (Production Example 4: Preparation of Crystalline Polyester Resin Dispersion C-1a) A vessel equipped with a stirrer and thermometer was charged with 45 parts of [Crystalline Polyester Resin C-1] and 450 parts of ethyl acetate. The mixture was heated to 80°C under stirring, maintained at 80°C for 5 hours, then cooled to 30°C over 1 hour. The mixture was dispersed in a bead mill (Ultraviscomill, manufactured by Imex Co., Ltd.) at a feed rate of 1 kg / h, a disk peripheral speed of 6 m / s, and 80% volumetric loading of 0.5 mm diameter zirconia beads. A 3-pass dispersion was performed to obtain [Crystalline Polyester Resin Dispersion C-1a]. The volume average particle size of the crystalline polyester resin particles in the resulting [Crystalline Polyester Resin Dispersion C-1a] was 450 nm, and the solids concentration was 10%.

[0177] <<Calculation method for solid concentration of crystalline polyester resin dispersion>> The solid content concentration of the crystalline polyester resin particles in the [crystalline polyester resin dispersion C-1a] obtained in Preparation Example 1 was calculated from the remaining amount by precisely weighing 0.9000 g to 1.0000 g of the [crystalline polyester resin dispersion C-1a] into an aluminum container, leaving it to stand in a thermostatic chamber with an internal temperature set to 150°C for 1 hour, and then removing it from the thermostatic chamber using the following formula. Solid content concentration [%] = (remaining amount [g] after standing at 150°C for 1 hour) / (precisely weighed amount of [crystalline polyester resin dispersion C-1a]) × 100

[0178] (Production Example 5: Preparation of Wax Dispersion 1) A vessel equipped with a stirrer and thermometer was charged with 50 parts of ester wax (WE-11, NOF Corporation, synthetic wax made from plant-derived monomers, melting point 67°C) as a release agent and 120 parts of ethyl acetate. The mixture was heated to 80°C with stirring and held at 80°C for 5 hours. After cooling to 30°C over 1 hour, the mixture was dispersed in a bead mill (Ultraviscomill, Aimex Co., Ltd.) at a feed rate of 1 kg / h, a disk peripheral speed of 6 m / s, and 80% volumetric loading of 0.5 mm diameter zirconia beads. Wax Dispersion 1 was obtained. The resulting Wax Dispersion 1 had a median diameter of 400 nm and a solids concentration of 25%.

[0179] <<How to calculate the solid concentration of wax>> The solids concentration of wax in [Wax Dispersion 1] obtained in Preparation Example 2 was calculated by precisely weighing 0.9000 g to 1.0000 g of [Wax Dispersion 1] into an aluminum container, leaving it to stand in a thermostatic bath with an internal temperature set to 150°C for 1 hour, removing it from the thermostatic bath, and using the remaining amount according to the following formula. Solid content [%] = (amount remaining after standing at 150°C for 1 hour [g]) / (precisely weighed amount of [wax dispersion 1]) × 100

[0180] <<Measurement of the median diameter of crystalline polyester resin dispersions and wax dispersions>> The median diameters of the [Crystalline Polyester Resin Dispersion C-1a] obtained in Preparation Example 1 and the [Wax Dispersion 1] obtained in Preparation Example 2 were measured under the following measurement conditions by putting the [Crystalline Polyester Resin Dispersion C-1a] or the [Wax Dispersion 1] in a dispersion state into a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.). [Measurement conditions] Solvent: Ethyl acetate Measurement cell: 10mL batch cell Circulation: Ultrasonic probe 30W, 22.5kHz Measurement sample volume: Transmittance 75% to 90% Measurement time: 20 seconds

[0181] (Production Example 6: Production of Masterbatch (MB)) 1,200 parts of water, 400 parts of carbon black (Printex 35, manufactured by Dexa) [DBP oil absorption = 42 mL / 100 mg, pH = 9.5], and 600 parts of [amorphous polyester resin A1] were mixed in a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd.), and the mixture was kneaded using two rolls at 150°C for 30 minutes, then rolled and cooled, and pulverized in a pulverizer to obtain [masterbatch 1].

[0182] (Production Example 7: Preparation of core emulsion) <Preparation of core oil phase> 51.1 parts of [Amorphous Polyester Resin A1], 64 parts of [Crystalline Polyester Resin Dispersion C-1a], 20 parts of [Wax Dispersion 1], 22.5 parts of [Masterbatch 1], and 14.4 parts of ethyl acetate were placed in a container and mixed at 5,000 rpm for 60 minutes using a TK Homomixer (manufactured by Primix Corporation) to obtain [Core Oil Phase 1]. The solids concentration of the obtained [Core Oil Phase 1] was 50%. The above blending amounts indicate the solids blending amounts of each raw material.

[0183] <<How to calculate the solid concentration of wax>> The solid content concentration in the [core oil phase 1] was calculated by precisely weighing 0.9000 g to 1.0000 g of [core oil phase 1] into an aluminum container, leaving it to stand in a thermostatic bath with an internal temperature set to 150°C for 1 hour, and then removing it from the thermostatic bath. Solid content [%] = (amount remaining after standing at 150°C for 1 hour [g]) / (precisely weighed amount of [core oil phase 1]) × 100

[0184] <Preparation of core aqueous phase> 990 parts of water, 20 parts of sodium dodecyl sulfate, and 90 parts of ethyl acetate were mixed and stirred to obtain a milky white liquid, which was designated as [core aqueous phase 1].

[0185] <Preparation of Core Emulsion CEM-1> While stirring 703 parts of [Core Oil Phase 1] in a TK Homomixer at 8,000 rpm, 5.1 parts of 28% aqueous ammonia was added so that the neutralization rate was 100% relative to the acid value of 18 mg KOH / g of [Amorphous Polyester Resin A1], and after mixing for 10 minutes, 1,197 parts of [Core Water Phase 1] was gradually added dropwise to phase-inversion emulsify [Core Oil Phase 1]. The phase-inversion emulsion of [Core Oil Phase 1] was further desolvated in an evaporator to obtain [Core Emulsion CEM-1]. The median diameter of [Core Emulsion CEM-1] was measured to be 210 nm, and the solid content was measured to be 25.0%.

[0186] <<Measurement of the median diameter of the core emulsion>> The median diameter of the [Core Emulsion CEM-1] was measured using a Nanotrac particle size distribution analyzer (UPA-EX150, Nikkiso Co., Ltd., dynamic light scattering method / laser Doppler method) under the following measurement conditions. [Measurement conditions] Measurement time: 30 seconds Sample loading amount: Loading Index 1.0 Particle conditions -Transparency: Transparent -Particle refractive index: 1.59 -Temperature: 25℃ -Particle shape: true spherical Solvent conditions Solvent: Water Solvent refractive index: 1.333 Viscosity at high temperature: 30℃, 0.797mPa·s Viscosity at low temperature: 20℃, 1.002mPa·s

[0187] <<Calculation method for solid concentration of core emulsion>> The solids concentration of the [core emulsion CEM-1] obtained in Preparation Example 4 was calculated by precisely weighing 0.9000 g to 1.0000 g of the [core emulsion] into an aluminum container, leaving it to stand in a thermostatic chamber with the internal temperature set to 150°C for 1 hour, removing it from the thermostatic chamber, and then calculating the solids concentration from the remaining amount using the following formula. Solid content [%] = (remaining amount [g] after standing at 150°C for 1 hour) / (precisely weighed [core element] Amount of emulsion) x 100

[0188] (Production Example 8: Production of Polyester Resin Emulsion SEM-1 for Shell) <Preparation of Polyester Resin Solution for Shell> 200 parts of [shell polyester resin SR-1] and 200 parts of methyl ethyl ketone were placed in a container and mixed at 5,000 rpm for 60 minutes using a TK Homomixer (manufactured by Primix Corporation) to obtain [polyester resin solution 1]. The solids concentration of the obtained [shell polyester resin solution 1] was 50%.

[0189] <<Calculation method for solid concentration of polyester resin solution for shell>> The solids concentration of [Shell polyester resin solution 1] was calculated using the following formula from the remaining amount after accurately weighing 0.9000 g to 1.0000 g of [Shell polyester resin solution 1] into an aluminum container and leaving it to stand in a thermostatic bath with an internal temperature set to 150°C for 1 hour and then removing it from the thermostatic bath. Solid content [%] = (remaining amount [g] after standing at 150 ° C for 1 hour) / (precisely weighed [shell Amount of polyester resin solution 1 [g] x 100

[0190] <Preparation of shell aqueous phase 1> 468 parts of water and 132 parts of methyl ethyl ketone were mixed and stirred to obtain a white transparent liquid, which was designated as [shell aqueous phase 1].

[0191] <Preparation of Polyester Resin Emulsion SEM-1 for Shell> While stirring 400 parts of the [shell polyester resin fat solution 1] solution in a TK Homomixer (manufactured by Primix Corporation) at 8,000 rpm, 28% ammonia water was added in an amount equivalent to 100% neutralization relative to the acid value of [polyester resin emulsion resin SR-1], and after mixing for 10 minutes, 600 parts of [shell aqueous phase 1] was gradually added dropwise to phase-invert emulsify [shell polyester resin solution 1]. The phase-inverted emulsion of [shell polyester resin solution 1] was then desolvated in an evaporator to obtain [shell polyester resin emulsion SEM-1].

[0192] (Production Example 9: Production of Polyester Resin Emulsions SEM-2 to SEM-41 for Shell) [Shell polyester resins (SR-2) to (SR-41)] were also prepared in the same manner as in the preparation of [Shell polyester resin emulsion SEM-1], to obtain [Shell polyester resin emulsions (SEM-2) to (SEM-41)].

[0193] <<Measurement of the median diameter of polyester resin emulsion for shell>> The median diameters of the obtained [shell polyester resin emulsions (SEM-1) to (SEM-41)] were measured in the same manner as for [core emulsion CEM-1]. The results are shown in Tables 1-1 to 1-4.

[0194] Example 1 <Agglomeration process> 100 parts of [Core Emulsion CEM-1] and 300 parts of ion-exchanged water were placed in a container and stirred for 1 minute. Next, 6.3 parts of a 20% aqueous magnesium sulfate solution was added dropwise, and the mixture was stirred for another 5 minutes, after which the temperature was raised to 55°C. The volume average particle size was then increased to 5.0 μm. The volume average particle size (Dv) was measured using a Coulter Multisizer III (aperture diameter 100 μm, manufactured by Beckman Coulter) and analysis software, Beckman Coulter Multisizer 3 (version 3.51, manufactured by Beckman Coulter). 10 mg of the measurement sample was added to 5 mL of 10 mass % surfactant (alkylbenzene sulfonate, Neogen SC-A, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the mixture was dispersed for 1 minute using an ultrasonic disperser. After that, an arbitrary amount of 25 mL of an electrolyte, Isoton III (manufactured by Beckman Coulter), was added, and the mixture was dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion. Next, 100 mL of the electrolyte and an appropriate amount of the sample dispersion were added to a beaker, and 30,000 particles were measured at a concentration that allowed the particle size of 30,000 particles to be measured in 20 seconds, and the volume average particle size (Dv) was calculated from the particle size distribution.

[0195] <Shelling process> When the particle size of the cores reached 5.0 μm in the aggregation step, 18.3 parts of [shell polyester resin emulsion SEM-1] diluted with 30 parts of water was added, and 15 parts of a 20% aqueous magnesium sulfate solution was added dropwise. The mixture was stirred for another 10 minutes, and then the temperature was raised to 65° C. and the mixture was stirred for 30 minutes.

[0196] <Fusing and stopping process> Next, 29 parts of sodium sulfate was added, and the mixture was heated to 70° C., and when the desired circularity of 0.957 to 0.962 was reached, the mixture was cooled to obtain [Toner Dispersion Liquid 1].

[0197] <Annealing process, washing process, and drying process> [Toner dispersion liquid 1] was stored at 45°C for 10 hours, filtered under reduced pressure, and washed and dried as follows. (1) 100 parts of ion-exchanged water was added to the filter cake, and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes), followed by filtration under reduced pressure. (2): 900 parts of ion-exchanged water was added to the filter cake (1), and the mixture was mixed with ultrasonic vibrations in a TK homomixer (at 12,000 rpm for 30 minutes), followed by vacuum filtration. This procedure was repeated until the electrical conductivity of the filtrate obtained by vacuum filtration reached 10 μC / cm or less, and then the mixture was filtered to obtain [Filter Cake 1]. [Filter cake 1] was dried in a circulating air dryer at 45° C. for 48 hours and sieved through a 75 μm mesh to obtain [colored resin particles 1].

[0198] <External attachment> 2.5 parts of inorganic fine particles (CAB-O-SIL (registered trademark) TS-530 fumed silica, manufactured by Cabosil Co.) were added to 100 parts of [colored resin particles 1], and the mixture was mixed with a Henschel mixer. The mixture was mixed at 40 m / sec for 10 minutes to obtain [Toner 1].

[0199] The properties of the obtained [Toner 1] are shown in Table 2.

[0200] (Examples 2 to 20) [Toner 2 to Toner 20] were obtained by producing under the same conditions as in Example 1, except that the combination of [core emulsion] and [shell resin emulsion] was changed to the combination shown in Table 2 below.

[0201] Example 21 Toner 21 was obtained under the same conditions as in Example 1, except that the amount of shell resin emulsion added in the shell formation step was 4.1 parts, the amount of magnesium sulfate added was 12.4 parts, and the amount of sodium sulfate added in the fusion and termination steps was 24.9 parts.

[0202] Example 22 Toner 22 was obtained under the same conditions as in Example 1, except that the amount of shell resin emulsion added in the shell formation step was 8.8 parts, the amount of magnesium sulfate added was 13.1 parts, and the amount of sodium sulfate added in the fusion and termination steps was 26.3 parts.

[0203] Example 23 Toner 23 was obtained under the same conditions as in Example 1, except that the amount of shell resin emulsion added in the shell formation step was 33.7 parts, the amount of magnesium sulfate added was 16.9 parts, and the amount of sodium sulfate added in the fusion and termination steps was 33.8 parts.

[0204] Example 24 Toner 24 was obtained under the same conditions as in Example 1, except that the amount of shell resin emulsion added in the shell formation step was 33.7 parts, the amount of magnesium sulfate added was 16.9 parts, and the amount of sodium sulfate added in the fusion and termination steps was 33.8 parts.

[0205] (Examples 25 to 27) The combination of [Core Emulsion] and [Shell Resin Emulsion] was changed to the combination shown in Table 2 below. Toners 25 to 27 were obtained by producing under the same conditions as in Example 1, except that the amount of shell resin emulsion added in the shell formation step was 4.1 parts, the amount of magnesium sulfate added was 12.4 parts, and the amount of sodium sulfate added in the fusion and termination steps was 24.9 parts.

[0206] Example 28 The combination of [Core Emulsion] and [Shell Resin Emulsion] was changed to the combination shown in Table 2 below. Toner 28 was obtained under the same conditions as in Example 1, except that the amount of shell resin emulsion added in the shell formation step was 3.3 parts, the amount of magnesium sulfate added was 12.3 parts, and the amount of sodium sulfate added in the fusion and termination steps was 24.6 parts.

[0207] (Examples 29 to 31) The combination of [Core Emulsion] and [Shell Resin Emulsion] was changed to the combination shown in Table 2 below. Toners 29 to 31 were obtained by producing under the same conditions as in Example 1, except that the amount of shell resin emulsion added in the shell formation step was 52.5 parts, the amount of magnesium sulfate added was 19.7 parts, and the amount of sodium sulfate added in the fusion and termination steps was 39.4 parts.

[0208] Example 32 The combination of [Core Emulsion] and [Shell Resin Emulsion] was changed to the combination shown in Table 2 below. Toner 32 was obtained under the same conditions as in Example 1, except that the amount of shell resin emulsion added in the shell formation step was 54.7 parts, the amount of magnesium sulfate added was 20.0 parts, and the amount of sodium sulfate added in the fusion and termination steps was 40.1 parts.

[0209] (Comparative Examples 1 to 13) Except for changing the combination of [core emulsion] and [shell resin emulsion] to the combination shown in Table 2, production was carried out under the same conditions as in Example 1 to obtain [Toner 33 to Toner 45].

[0210] The properties of [Toner 1] to [Toner 45] obtained in Examples 1 to 32 and Comparative Examples 1 to 13 are shown in Table 2 below.

[0211] <<Volume average particle size of toner>> The volume average particle diameter (Dv) of the toner was measured using a Coulter Multisizer III (aperture diameter 100 μm, manufactured by Beckman Coulter) and analysis software Beckman Coulter Multisizer 3 (version 3.51, manufactured by Beckman Coulter). The measurement conditions were the same as those for measuring the volume average particle size in the aggregation step.

[0212] <<Average circularity of toner>> The average circularity of resin particles and toner, as well as the amount of fine powder of 2 μm or less, were measured using a flow particle image analyzer FPIA-3000 (manufactured by SYSMEX Co., Ltd.). After preparing a 1% NaCl aqueous solution using grade 1 sodium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 0.1 to 5 ml of alkylbenzene sulfonate (Neogen, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added as a dispersant to 50 to 100 ml of the solution, and 1 to 10 mg of the sample was added. This was subjected to dispersion treatment for 1 minute using an ultrasonic disperser, and measurements were carried out using a dispersion liquid in which the particle concentration was adjusted to 5000 to 15000 particles / μl.

[0213] <<Evaluation of cohesion during the fusion process>> The cohesion during the fusion step was evaluated by the following evaluation method. The difference in volume average particle size ΔDv between the resin particles one hour after the predetermined fusion temperature was reached and the core particles before the shell was added was calculated using the following formula (1) to evaluate the aggregation stability during fusion. ΔDv = volume average particle diameter of resin particles 1 hour after reaching the specified fusion temperature - volume average particle diameter of core before adding shell Equation (1) One hour after reaching the specified fusion temperature, the particle sizes of the resin particles and the core particles before adding the shell were measured as volume average particle sizes using a Beckman Coulter Multisizer II. The measurement method is described below. 0.03 to 0.06 g of the resin particle slurry after fusion or the core particle slurry before the addition of the shell was collected and placed in a 100 ml beaker containing 10 ml of ion-exchanged water to prepare a measurement sample. The measurement sample was stirred with a microspatula and then dispersed for 1 minute using an ultrasonic disperser (manufactured by Honda Electronics Co., Ltd.). The volume average particle size of the dispersed measurement sample was measured using the Multisizer II with a 100 μm aperture. ◎ and ◯ indicate a range that is acceptable for practical use. -Evaluation criteria for cohesion during the fusion process- ◎: Less than ΔDv0.5 ○: ΔDv 0.5 or more and less than 1.0 △: ΔDv 1.0 or more and less than 1.5 ×: ΔDv1.5 or higher

[0214] The evaluation results of the cohesion during the fusion step in Examples 1 to 32 and Comparative Examples 1 to 13 are shown in Table 3 below.

[0215] <<Evaluation of free shells>> The free shell was measured for both (1) emulsion particles not attached to the core and (2) homo-aggregated shell emulsion particles, and a comprehensive evaluation was made. (Evaluation of core-unattached shell) After fusion, 0.5 ml of the slurry was collected in a 15 ml centrifuge tube. The centrifuge tube was placed in a centrifuge (Hitachi Himac CF15RX) and the slurry was subjected to solid-liquid separation at 1000 rpm for 3 minutes. The centrifuge tube was removed and the supernatant was observed to evaluate the free shell by observing the shell emulsion particles that had not adhered to the core.

[0216] (shell homoaggregate measurement) Measurements were performed using a flow particle image analyzer ("FPIA-3000"; manufactured by Sysmex Corporation), and the number of particles with a diameter of 2 μm or less was measured using analysis software (FPIA-3000 Part 11 Version 00-11). Specifically, 0.03 to 0.06 g of the slurry after fusion was collected and placed in a 100 ml beaker containing 10 ml of ion-exchanged water to prepare a measurement sample. The measurement sample was stirred with a microspatula and then dispersed for 1 minute using an ultrasonic disperser (manufactured by Honda Electronics Co., Ltd.). The dispersed measurement sample was measured using the FPIA-3000 until a concentration of 5,000 to 15,000 particles / μl was obtained, and the proportion of particles with a diameter of 2 μm or less was evaluated. ◎, ◯, and △ indicate ranges that are acceptable for practical use. -Evaluation criteria for free shells- ◎: Clear supernatant 2μm↓less than 5% 〇: Clear supernatant 2μm↓5% to less than 10% △: Supernatant is white and transparent or 2μm↓10% to less than 15% ×: White supernatant or 2μm↓15% or more

[0217] The evaluation results of the free shells in Examples 1 to 32 and Comparative Examples 1 to 13 are shown in Table 4 below.

[0218] <Preparation of developer> <<Creating a carrier>> To 100 parts of toluene, 100 parts of silicone resin (organostraight silicone), 5 parts of γ-(2-aminoethyl)aminopropyltrimethoxysilane, and 10 parts of carbon black were added, and the mixture was dispersed using a homomixer for 20 minutes to prepare a resin layer coating liquid. Using a fluidized bed coating device, the resin layer coating liquid was applied to the surface of 1,000 parts by mass of spherical magnetite having a volume average particle size of 50 μm, to prepare a carrier.

[0219] <<Preparation of Developers 1 to 45>> Using a ball mill, 5 parts of each of [Toner 1] to [Toner 45] and 95 parts of [Carrier] were mixed to prepare two-component [Developer 1] to [Developer 45] for Examples 1 to 32 and Comparative Examples 1 to 13.

[0220] <Toner Evaluation> Next, the various properties of each of the toners and developers obtained were evaluated as follows, and the results are shown in Table 5 below.

[0221] <<Low temperature fixability>> A 2cm x 15cm solid image was printed on paper (PPC paper type 6000<70W> A4 T-line, manufactured by Ricoh Co., Ltd.) with a toner adhesion of 0.40mg / cm 2 The developer was developed so that the image was as follows: Here, the developer was applied to the paper surface using a printer (imagio MP C5503, manufactured by Ricoh Co., Ltd.) with the thermal fixing unit removed. The paper was passed through a pressure roller at a fixing speed (heating roller peripheral speed) of 213 mm / sec and a fixing pressure (pressure roller pressure) of 10 kg / cm2, and the temperature at which cold offset occurred (MFT) was measured, and low-temperature fixability was evaluated based on the following evaluation criteria. Note that a lower temperature at which cold offset occurred indicates better low-temperature fixability. ◎, ◯, and △ indicate ranges that are acceptable for practical use. -Evaluation criteria for low-temperature fixability- ◎: Cold offset occurrence temperature (MFT) is 130℃ or less ○: The temperature at which cold offset occurs (MFT) is over 130℃ and 135℃ or less △: Cold offset occurrence temperature (MFT) is over 135℃ and 140℃ or less ×: The temperature at which cold offset occurs (MFT) is over 140°C

[0222] <<Heat-resistant storage stability>> The toner was filled into a 50 mL glass container and left in a thermostatic chamber at 50°C for 24 hours, and then cooled to 24°C. Next, the penetration [mm] was measured using a penetration test (JIS K 2235-1991), and the heat-resistant storage stability was evaluated based on the following evaluation criteria. ◎ and ◯ are in a range where there are no practical problems. -Evaluation criteria for heat resistance and storage stability- ◎: Penetration is 20mm or more ○: Penetration is 15mm or more and less than 20mm △: Penetration is 10mm or more and less than 15mm ×: Penetration less than 10 mm

[0223] The evaluation results of the heat-resistant storage stability in Examples 1 to 32 and Comparative Examples 1 to 13 are shown in Table 5 below.

[0224] [Table 1-1]

[0225] [Table 1-2]

[0226] [Table 1-3]

[0227] [Table 1-4]

[0228] [Table 2]

[0229] [Table 3]

[0230] [Table 4]

[0231] [Table 5]

[0232] From the results in Table 5, it was found that Examples 1 to 32 of the present invention exhibited excellent performance in all of the cohesion during the fusion step, the free shell, the low-temperature fixability, and the heat-resistant storage stability. On the other hand, Comparative Examples 1 to 5 and 9 to 13 exhibit poor cohesion during fusion and have many free shells. In addition, although the amount of free shell was small in Comparative Examples 6 to 8, the cohesion during fusion was significantly deteriorated. Due to this condition, the comparative examples did not sufficiently form a shell on the core, and the heat-resistant storage stability was deteriorated.

[0233] The present invention includes, for example, the following aspects. (1) A polyester resin emulsion for toner, comprising resin particles (S) containing a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component dispersed in an aqueous medium, the alcohol component contains a trihydric or tetrahydric alcohol having a linear or branched aliphatic saturated hydrocarbon skeleton having 4 to 6 carbon atoms, the polyester resin (A) contains a sulfonate group, and when the acid value of the polyester resin (A) is AV (mg KOH / g) and the hydroxyl value of the polyester resin (A) is OHV (mg KOH / g), OHV / AV is 0.4 or more and 1.1 or less; A polyester resin emulsion characterized by: (2) The polyester resin emulsion according to (1) above, wherein the content of sulfonate groups in the polyester resin (A) is 2 mol % or more and 10 mol % or less based on the total amount of carboxylic acid monomers constituting the polyester resin (A). (3) The polyester resin emulsion according to (1) or (2) above, wherein the acid value (AV) of the polyester resin (A) is 10 or more and 25 mgKOH / g or less, and the hydroxyl value (OHV) of the polyester resin (A) is 5 mgKOH / g or more and 19 mgKOH / g or less. (4) The polyester resin emulsion according to any one of (1) to (3) above, which is a shell-forming resin emulsion used in the production of a toner having a core-shell structure consisting of core particles containing a binder resin and a shell covering the core particles. (5) A method for producing resin particles having a core-shell structure consisting of core particles containing a binder resin and a shell covering the core particles, the method comprising at least the following steps (1) to (4): (1) A step of dissolving or dispersing at least a polyester resin and a release agent in an organic solvent to obtain a solution or dispersion. (2) A step of suspending the solution or dispersion in an aqueous medium to produce a core particle dispersion. (3) A step of adding the polyester resin emulsion for toner according to any one of (1) to (4) above to the core particle dispersion to form a shell on the surface of the core particles. (4) Removing the organic solvent (6) The method for producing resin particles according to (5) above, wherein the content of the shell in the resin particles is 5% by mass or more and 40% by mass or less. (7) A method for producing a toner having a core-shell structure consisting of core particles containing a binder resin and a shell covering the core particles, the method comprising at least the following steps (1) to (4): (1) A step of dissolving or dispersing at least a polyester resin and a release agent in an organic solvent to obtain a solution or dispersion. (2) suspending the solution or dispersion in an aqueous medium to produce a core particle dispersion; (3) A step of adding the polyester resin emulsion for toner according to any one of (1) to (4) above to the core particle dispersion to form a shell on the surface of the core particles. (4) Removing the organic solvent

[0234] According to the polyester resin emulsion for toner described in any one of (1) to (4) above, the conventional problems can be solved and the object of the present invention can be achieved. [Explanation of symbols]

[0235] 160Y Sub Hopper (Yellow) 160C Sub Hopper (Cyan) 160M Sub Hopper (Magenta) 160K Sub Hopper (Black) 180Y Image Forming Unit (Yellow) 180C Image Forming Unit (Cyan) 180M Image Forming Unit (Magenta) 180K Image Forming Unit (Black) 210 Paper feed section 211 Paper cassette 212 Paper feed roller 220 Conveyor 221 Laura 222 Timing roller 223 Paper ejection roller 224 Paper output tray 230 Image creation section 231Y Photoconductor drum (yellow) 231C Photoconductor drum (cyan) 231M Photoconductor Drum (Magenta) 231K Photoconductor Drum (Black) 232Y Charger (Yellow) 232C Charger (cyan) 232M Charger (Magenta) 232K Charger (Black) 233 Exposure device 233a light source 233bY Polygon Mirror (Yellow) 233bC Polygon Mirror (Cyan) 233bM Polygon Mirror (Magenta) 233bK Polygon Mirror (Black) 234Y Toner Bottle (Yellow) 234C Toner Bottle (Cyan) 234M Toner Bottle (Magenta) 234K Toner Bottle (Black) 236Y Cleaning Device (Yellow) 236C Cleaner (cyan) 236M Cleaner (Magenta) 236K Cleaning Tool (Black) 240 Transcription Unit 241 Drive roller 242 driven roller 243 Intermediate transfer belt 244 Primary transfer roller 244Y Primary Transfer Roller (Yellow) 244C Primary transfer roller (cyan) 244M Primary Transfer Roller (Magenta) 244K Primary Transfer Roller (Black) 245 Secondary opposing roller 246 Secondary transfer roller 250 Fixing unit 251 Fixing belt 252 pressure roller L Laser P paper [Prior art documents] [Patent documents]

[0236] [Patent Document 1] Patent No. 6632066

Claims

1. A polyester resin emulsion for toner, comprising resin particles (S) dispersed in an aqueous medium, the resin particles (S) including a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component, the alcohol component contains a trihydric or tetrahydric alcohol having a linear or branched aliphatic saturated hydrocarbon skeleton having from 4 to 6 carbon atoms, the polyester resin (A) contains a sulfonate group, and when the acid value of the polyester resin (A) is AV (mg KOH / g) and the hydroxyl value of the polyester resin (A) is OHV (mg KOH / g), OHV / AV is 0.4 or more and 1.1 or less; A polyester resin emulsion characterized by:

2. 2. The polyester resin emulsion according to claim 1, wherein the content of sulfonate groups in the polyester resin (A) is 2 mol % or more and 10 mol % or less based on the total amount of carboxylic acid monomers constituting the polyester resin (A).

3. 3. The polyester resin emulsion according to claim 1, wherein the acid value (AV) of the polyester resin (A) is 10 to 25 mgKOH / g, and the hydroxyl value (OHV) of the polyester resin (A) is 5 to 19 mgKOH / g.

4. 3. The polyester resin emulsion according to claim 1, which is a shell-forming resin emulsion used in the production of a toner having a core-shell structure comprising core particles containing a binder resin and a shell covering the core particles.

5. A method for producing resin particles having a core-shell structure consisting of core particles containing a binder resin and a shell covering the core particles, the method comprising at least the following steps (1) to (4): (1) A step of dissolving or dispersing at least a polyester resin and a release agent in an organic solvent to obtain a solution or dispersion. (2) A step of suspending the solution or dispersion in an aqueous medium to produce a core particle dispersion. (3) A step of adding the polyester resin emulsion for toner according to claim 1 or 2 to the core particle dispersion to form a shell on the surface of the core particles. (4) Removing the organic solvent

6. The method for producing resin particles according to claim 5 , wherein the content of the shell in the resin particles is 5% by mass or more and 40% by mass or less.

7. A method for producing a toner having a core-shell structure consisting of core particles containing a binder resin and a shell covering the core particles, the method comprising at least the following steps (1) to (4): (1) A step of dissolving or dispersing at least a polyester resin and a release agent in an organic solvent to obtain a solution or dispersion. (2) suspending the solution or dispersion in an aqueous medium to produce a core particle dispersion; (3) A step of adding the polyester resin emulsion for toner according to claim 1 or 2 to the core particle dispersion to form a shell on the surface of the core particles. (4) Removing the organic solvent

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