Polyester resin emulsion for toner, method for manufacturing resin particle, and method for manufacturing toner

Abstract

To provide a polyester resin emulsion for toner that has a core-shell structure, and is excellent in cohesiveness of shell particles to core particles and uniformity of the shell particles.SOLUTION: A polyester resin emulsion for toner has resin particles (S) dispersed in an aqueous medium, the resin particles including a polyester resin (A) obtained through polycondensation of an alcohol component and a carboxylic acid component. The alcohol component includes tri- or tetra-valent alcohol having, as a skeleton, straight-chain or branched aliphatic saturated hydrocarbon having 4 or more and 6 or less carbon atoms. The ratio of the hydroxyl value (OHV) of the polyester resin (A) to the acid value (AV) of the polyester resin (A) is 0.30 or more and 1.00 or less, and the AV is 10 mgKOH / g or more 25 mgKOH / g or less. The polyester resin (A) contains a repeating unit derived from polyethylene terephthalate (PET) in an amount of 40 mass% or more and 70 mass% 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 Art

[0002] For toners used in electrophotographic image forming apparatuses, toners having excellent low-temperature fixability are required due to market demands for energy conservation. Also, toners having excellent blocking resistance in which toner particles do not fuse with each other even under harsh environments such as high temperature and high humidity, and toners having excellent mechanical durability that can sufficiently withstand stress accompanying high-speed output of image forming apparatuses are required. In recent years, for the purpose of imparting heat resistance and mechanical durability, development of toners having a so-called core-shell structure in which a shell formed from shell particles is provided on the surface of core particles has been progressing. Although various techniques for core-shell formation of toners have been proposed and put into practical use, chemical toners using a polyester resin excellent in low-temperature fixability for both core particles and shell particles have become mainstream.

[0003] For example, an electrostatic charge developing toner in which polyethylene terephthalate (PET) is blended with the resin in the core part and the shell part has been proposed (see, for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] In these toners having a core-shell structure, the adhesion state of the shell to the core particles is important. If the shell is not uniformly adhered or is peeled off due to stirring stress in the developing machine or the like, it will have an adverse effect on the stability of toner characteristics such as chargeability. An object of the present invention is to provide a polyester resin emulsion for toner from which a toner having a core-shell structure, excellent mechanical durability, and excellent charge stability over long-term use can be obtained.

Means for Solving the Problems

[0005] The polyester resin emulsion for toner of the present invention as a means for solving the above problems is a polyester resin emulsion for toner in which resin particles (S) containing a polyester resin (A) obtained by polycondensing an alcohol component and a carboxylic acid component are dispersed in an aqueous medium, the alcohol component includes a trivalent or tetravalent alcohol having a straight-chain or branched aliphatic saturated hydrocarbon having 4 to 6 carbon atoms as a skeleton, when the acid value of the polyester resin (A) is AV (mgKOH / g) and the hydroxyl value of the polyester resin (A) is OHV (mgKOH / g), OHV / AV is 0.30 or more and 1.00 or less, and the AV is 10 mgKOH / g or more and 25 mgKOH / g, the polyester resin (A) contains 40% by mass or more and 70% by mass or less of repeating units derived from polyethylene terephthalate (PET) which is a condensate of terephthalic acid and ethylene glycol, which is a polyester resin emulsion for toner, characterized by the above.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a polyester resin emulsion for toner that can obtain a toner excellent in mechanical durability and can obtain a toner excellent in charge stability even after long-term use.

Brief Description of the Drawings

[0007]

Figure 1

Embodiments for Carrying Out the Invention

[0008] In the case of a toner having a core-shell structure, from the viewpoints of low-temperature fixability, heat-resistant storage stability, charge stability, and mechanical durability of the toner, it is known that it is very important that the shell formed on the surface of the core particles is uniformly arranged and there are no defective portions. More specifically, when the shell is not arranged uniformly and without defective portions with respect to the surface of the core particles, due to a decrease in the mechanical durability of the toner, the shell may be peeled off from the core particles due to development stress or the like in the image forming apparatus, and there is concern that each toner performance may deteriorate significantly.

[0009] In the prior art described in Patent Document 1, by introducing polyethylene terephthalate (PET) into the shell portion of the toner having a core-shell structure, the durability of the toner and the exposure of wax on the toner surface are suppressed. However, when polyethylene terephthalate (PET) is introduced into the shell particles forming the shell portion, there is concern that the cohesiveness of the core particles and the shell particles may decrease due to a decrease in the hydrophobicity of the shell particles, making it difficult to form a uniform shell on the surface of the core particles.

[0010] As a result of intensive studies by the present inventors, when forming a core-shell structure, that is, when aggregating shell particles on the surface of core particles, when the acid value of the polyester resin (A) is AV (mgKOH / g) and the hydroxyl value of the polyester resin (A) is OHV (mgKOH / g), by using an emulsion in which a polyester resin having a ratio (OHV / AV) of the hydroxyl value (OHV) to the acid value (AV) within a specific numerical range is dispersed in an aqueous medium, the aggregability and aggregation uniformity of the shell particles with respect to the core particles are improved, and a toner and a developer having excellent mechanical durability and excellent charge stability even after long-term use can be obtained. Specifically, it is as follows.

[0011] When producing toner having a core-shell structure, for the dispersion liquid in which core particles are dispersed, a resin emulsion containing shell particles is dispersed, and the shell particles are aggregated on the surface of the core particles by utilizing the collision energy between particles by stirring, the thermal energy by heating, and 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 of the shell particles with respect to the core particles, but also affect the adhesiveness with the core particles when the shell particles are heat-fused to form a shell layer.

[0012] Typical properties of the resin constituting the shell particles include acid value (AV), hydroxyl value (OHV), hydrophilicity / hydrophobicity, affinity with a solvent, melt viscosity, and the like. Among these, when the ratio (OHV / AV) of the hydroxyl value (OHV) to the acid value (AV) in the resin constituting the shell particles is 0.30 or more and 1.00 or less, the aggregability of the shell particles with respect to the core particle surface is good, and they aggregate and are arranged uniformly with respect to the core particle surface (aggregation uniformity), are not easily peeled off even by the stirring stress in the developing machine, and the present inventors have found that a shell excellent in charge stability can be formed. The ratio (OHV / AV) can be controlled by using a trivalent or tetravalent alcohol having a straight-chain or branched aliphatic saturated hydrocarbon having 4 to 6 carbon atoms as a skeleton as an alcohol component in the resin.

[0013] The details of the present invention will be described below.

[0014] (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.

[0015] <Resin particles (S)> The resin particles (S) contain a polyester resin (A) and may contain other components as necessary.

[0016] <<Volume average particle diameter of resin particles (S)>> The volume average particle diameter of the resin particles (S) in the polyester resin emulsion for toner is not particularly limited and can be appropriately selected according to the purpose. It is preferably 0.05 μm or more and 0.8 μm or less in terms of median diameter (D50), 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 diameter of the resin particles (S) is 0.05 μm or more in terms of median diameter (D50), the aggregation efficiency of the shell particles with respect to the core particles becomes good, and a shell with sufficient thickness can be formed on the toner surface, which is preferable. When the volume average particle diameter of the resin particles (S) is 0.8 μm or less in terms of median diameter (D50), the aggregation of the shell particles with respect to the core particles becomes uniform, and a sufficiently uniform shell can be formed, which is preferable.

[0017] The method for measuring the median diameter (D50) is not particularly limited and can be appropriately selected according to the purpose. For example, it can be measured using a laser particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.).

[0018] <<Polyester resin (A)>> The polyester resin (A) is a polyester resin obtained by polycondensing an alcohol component and a carboxylic acid component, and contains a repeating unit derived from polyethylene terephthalate (PET). Optionally, it may contain other alcohols and other resins.

[0019] <<<Alcohol component>>> The alcohol component contains a trivalent or tetravalent alcohol having a straight-chain or branched aliphatic saturated hydrocarbon with 4 to 6 carbon atoms as a skeleton. In this specification, the "trivalent or tetravalent alcohol having a straight-chain or branched aliphatic saturated hydrocarbon with 4 to 6 carbon atoms as a skeleton" may sometimes be simply referred to as "alcohol". Note that an alcohol not corresponding to the "trivalent or tetravalent alcohol having a straight-chain or branched aliphatic saturated hydrocarbon with 4 to 6 carbon atoms as a skeleton" may sometimes be referred to as "other alcohol". In this specification, the "straight-chain" means a structure having no carbon-carbon bond other than a carbon chain (hereinafter sometimes referred to as the "main chain") that is connected by the minimum number of carbon atoms between two oxygen atoms appropriately selected from the oxygen atoms derived from the hydroxyl group in the monomer unit of the alcohol component. In this specification, the "branched" means a structure having a carbon-carbon bond other than the main chain.

[0020] By including, as the alcohol component, a trivalent or tetravalent alcohol having a straight-chain or branched saturated aliphatic with 4 to 6 carbon atoms as a skeleton in the polyester resin (A), the hydroxyl value (OHV) of the polyester resin (A) can be controlled, and the aggregability and adhesiveness to the core particles can be improved.

[0021] The alcohol is not particularly limited as long as it has a straight-chain or branched aliphatic saturated hydrocarbon with 4 to 6 carbon atoms as a skeleton and is trivalent or tetravalent, and can be appropriately selected according to the purpose. For example, trivalent aliphatic alcohols with 4 to 6 carbon atoms, tetravalent aliphatic alcohols with 4 to 6 carbon atoms, and the like can be mentioned. Examples of the trivalent aliphatic alcohol 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, 2-isopropylpropane-1,2,3-triol, and the like. Examples of the tetravalent aliphatic alcohol having 4 to 6 carbon atoms include pentaerythritol, 1,2,3,4 - butanetetraol (erythritol), 1,2,3,4 - pentanetetraol, 1,2,3,5 - pentanetetraol, 1,2,4,5 - pentanetetraol, 1,2,4,5 - hexanetetraol, 1,2,5,6 - hexanetetraol, and the like. These alcohols may be used alone or in combination of two or more.

[0022] The content of the alcohol is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.5 mol% or more and 10 mol% or less, more preferably 2 mol% or more and 5 mol% or less, based on the total amount of the alcohol components in the polyester resin (A). When the content of the alcohol is 0.5 mol% or more based on the total amount of the alcohol components in the polyester resin (A), it is suitable because problems such as insufficient cohesiveness of the shell particles to the core particles and an increase in shell particles not incorporated into the shell can be solved. When the content of the alcohol is 10 mol% or less based on the total amount of the alcohol components in the polyester resin (A), it is suitable because problems such as an increase in the branched chains of the polyester resin (A) and a resulting decrease in the melt viscosity of the shell in the toner, leading to insufficient heat storage stability and hot offset resistance, can be solved.

[0023] <<<Carboxylic acid>>> The carboxylic acid is not particularly limited and can be appropriately selected according to the purpose. For example, aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid or their anhydrides; aliphatic carboxylic acids with three or more valences such as 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, tetra(methylene carboxy)methane, 1,2,7,8-octanetetracarboxylic acid or their anhydrides; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid or their anhydrides; aromatic carboxylic acids with three or more valences such as trimellitic acid, pyromellitic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid or their anhydrides, partial lower alkyl esters, etc. may be mentioned. These carboxylic acids may be used alone or in combination of two or more.

[0024] The method of polycondensation of the alcohol component and the carboxylic acid component is not particularly limited and can be appropriately selected according to the purpose. For example, it can be carried out at a temperature of 180°C to 250°C in an inert gas atmosphere and in the presence of an esterification catalyst.

[0025] The esterification catalyst is not particularly limited and can be appropriately selected according to the purpose. For example, titanium compounds and tin(II) compounds having no Sn-C bond may be mentioned. These esterification catalysts may be used alone or in combination of two or more.

[0026] The titanium compound is not particularly limited and can be appropriately selected according to the purpose. For example, titanium diisopropylate bis(triethanolamineate), titanium diisopropylate bis(diethanolamineate), titanium dipentylate bis(triethanolamineate), titanium diethoxide bis(triethanolamineate), titanium dihydroxyoctylate bis(triethanolamineate), titanium distearate bis(triethanolamineate), titanium triisopropylate triethanolamineate, titanium monopropylate tris(triethanolamineate), tetra-n-butyl titanate, tetrapropyl titanate, tetrastearyl titanate, tetramyristyl titanate, tetraoctyl titanate, dioctyl dihydroxyoctyl titanate, dimyristyl dioctyl titanate, etc. can be mentioned. Among these, from the viewpoint of high activity and the ability to reduce the low molecular weight components of the polyester resin, a titanium compound having a Ti-O bond is preferable, and a compound having an alkoxy group, an alkenyloxy group, or an acyloxy group with a total carbon number of 1 to 28 is more preferable.

[0027] The content of the titanium compound is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of controlling the reaction rate in polymerization and ensuring the quality of the polyester resin, it is preferably 0.01 part by mass or more and 1.0 part by mass or less, more preferably 0.1 part by mass or more and 0.5 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0028] The tin(II) compound having no Sn-C bond is not particularly limited and can be appropriately selected according to the purpose. However, a tin(II) compound having an Sn-O bond and a tin(II) compound having an Sn-X (X represents a halogen atom) bond are preferable, and a tin(II) compound having an Sn-O bond is more preferable. Examples of the tin(II) compound having the Sn—O bond include tin(II) oxalate, tin(II) acetate, tin(II) octanoate, tin(II) 2-ethylhexanoate, tin(II) laurate, tin(II) stearate, tin(II) oleate, etc., which are tin(II) carboxylates having a carboxylic acid group with 2 to 28 carbon atoms; alkoxytin(II) such as octyloxytin(II), lauryloxytin(II), stearoxytin(II), oleoyloxytin(II), etc., which have an alkoxy group with 2 to 28 carbon atoms; tin(II) oxide; tin(II) sulfate, etc. Examples of the tin(II) compound having the Sn—X bond include tin(II) halides such as tin(II) chloride and tin(II) bromide.

[0029] The content of the tin(II) compound is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of controllability of the reaction rate in polymerization and quality assurance of the polyester resin, it is preferably 0.01 to 1.0 part by mass, more preferably 0.1 to 0.5 part by mass, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0030] 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 appropriately selected according to the purpose. However, from the viewpoints of controllability of the reaction rate in polymerization and quality assurance of the polyester resin, it is preferably 0.01 to 1.0 part by mass, more preferably 0.1 to 0.5 part by mass, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0031] <<<Other alcohols>>> In the polyester resin (A) of the present invention, other alcohols may be contained in addition to the above-mentioned alcohol. The other alcohol is not particularly limited and can be appropriately selected according to the purpose. For example, 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, 1,12-dodecanediol; diols having an oxyalkylene group such as diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol, 1,4-sorbitan, hydrogenated bisphenol A; those obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide to the alicyclic diol; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; alkylene oxide adducts of bisphenols such as those obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide to the bisphenols; polyhydric aliphatic alcohols having a valence of 3 or more such as heptanetriol, octanetriol, decanetriol, sorbitol, and dipentaerythritol; polyphenols such as trisphenol, phenol novolak, and cresol novolak; alkylene oxide adducts of polyphenols such as those obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide to the polyphenols, and the like can be mentioned. Among these, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol are preferable. By using these diols as other alcohol components in the polyester resin (A), it is possible to form a shell excellent in the balance between low-temperature fixability and mechanical durability, and it is suitable because the cohesiveness and uniformity of the shell particles with respect to the core particles are good. Further, from the viewpoint of reducing the amount of carbon dioxide emissions when the obtained toner is finally incinerated and discarded, it is more preferable that these diols are derived from biomass. In the present 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.

[0032] When using 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol as the other alcohol, it is preferable to contain at least one or more selected from these diols in an amount of 30 mol% or more based on the total amount of the alcohol components, more preferably 50 mol% or more, and even more preferably 80 mol% or more. 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). When the total content of 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol is 30 mol% or more based on the total amount of the alcohol components in the polyester resin (A), it is suitable because low-temperature fixability, mechanical durability, and environmental load reduction effects can be obtained.

[0033] <<<Repeating unit derived from polyethylene terephthalate (PET)>>> In addition to the above components, the polyester resin (A) of the present invention contains a repeating unit derived from so-called polyethylene terephthalate (PET), which is a condensate of terephthalic acid and ethylene glycol. In this specification, the "repeating unit derived from polyethylene terephthalate (PET)" may be referred to as the "PET repeating unit". Since the polyester resin (A) containing the PET repeating unit is excellent in mechanical durability, it can be suitably applied to the shell of a toner having a core-shell structure. Further, from the viewpoint of reducing the environmental load such as reducing the amount of petroleum resources used, it is preferable to use so-called recycled PET, which is recycled as a raw material, as the PET.

[0034] The polyester resin (A) containing the PET repeating unit can be obtained by carrying out polycondensation while causing a transesterification reaction with the above-described polyester resin (A) material.

[0035] As described above, in the prior art, when PET is introduced into the shell particles forming the shell, there is a concern that the cohesiveness of the core particles and the shell particles decreases due to the decrease in the hydrophobicity of the shell particles, making it difficult to produce a uniform shell on the surface of the core particles. On the other hand, in the polyester resin emulsion for toner of the present invention, since the ratio (OHV / AV) of the polyester resin (A) is 0.30 or more and 1.00 or less, the hydrophobicity is appropriately maintained, and hetero-aggregation with the core particles is likely to occur preferentially. Even when PET is introduced into the shell particles, the cohesiveness and adhesion with the core particles are not impaired. Further, the shell is less likely to peel off from the surface of the core particles, and charge stability is obtained.

[0036] The content of the PET repeating unit is not particularly limited and can be appropriately selected according to the purpose, but it is preferably 40% by mass or more and 70% by mass or less, more preferably 50% by mass or more and 60% by mass or less, based on the total amount of the polyester resin (A). When the content of the PET repeating unit is 40% by mass or more based on the total amount of the polyester resin (A), it is suitable because the mechanical durability is excellent. When the content of the PET repeating unit is 70% by mass or less based on the total amount of the polyester resin (A), it is suitable because the solubility in an organic solvent and the low-temperature fixing property are improved.

[0037] [Ratio (OHV / AV) of the polyester resin (A)] 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) is 0.30 or more and 1.00 or less, and preferably 0.65 or more and 1.0 or less. In this specification, "the ratio (OHV / AV) of the hydroxyl value (OHV) of the polyester resin (A) to the acid value (AV) of the polyester resin (A)" may be referred to as "ratio (OHV / AV)". When the ratio (OHV / AV) is 0.30 or more and 1.00 or less, the aggregability of the shell particles with respect to the core particles deteriorates, and the shell particles cannot be uniformly arranged on the surface of the core particles, resulting in defects in the formed shell, or an increase in the proportion of shell particles that do not aggregate with respect to the core particles, and the non-aggregating shell particles remaining as fine powder in the toner, which can solve the problem of deterioration of toner quality and is suitable. Further, when the shell particles are heated and melted to form a shell, the adhesion of the shell particles to the core particles is improved, making the shell less likely to peel off, which is suitable. Furthermore, setting it within this range results in excellent charge stability of the toner, and the charge amount is very stable even against the agitation stress in the developing machine, which is suitable.

[0038] The acid value (AV) of the polyester resin (A) in the present invention is 10 mgKOH / g or more and 25 mgKOH / g or less, and preferably 18 mgKOH / g or more and 25 mgKOH or less. When the acid value (AV) is 10 mgKOH / g or more, the stability as an emulsion becomes good, problems such as being difficult to emulsify can be solved, and also the cohesiveness of the shell particles with respect to the core particles becomes good, so it is suitable. Also, the chargeability of the toner can be appropriately expressed, and it is excellent in charge retention. When the acid value (AV) is 25 mgKOH / g or less, the charge stability of the toner against environmental variations is good, and also the cohesiveness of the shell particles with respect to the core particles becomes good, so it is suitable.

[0039] As a method for measuring the acid value (AV) of the polyester resin (A), it can be measured by the method of JIS K0070.

[0040] Regarding the hydroxyl value (OHV) of the polyester resin (A), when the acid value (AV) is 10 mgKOH / g or more and 25 mgKOH / g or less, it is preferable that the hydroxyl value (OHV) is 3 mgKOH / g or more and 25 mgKOH / g or less.

[0041] As a method for measuring the hydroxyl value (OHV) of the polyester resin (A), it can be measured by the method of JIS K0070.

[0042] [Glass transition temperature (Tg) of polyester resin (A)] The second glass transition temperature (Tg) upon heating by differential scanning calorimetry (DSC) of the polyester resin (A) is not particularly limited and can be appropriately selected according to the purpose, but it is preferably 65°C or more and 75°C or less. In this specification, the "second glass transition temperature (Tg) upon heating by differential scanning calorimetry (DSC)" may be referred to as "Tg2nd". When the Tg2nd of the polyester resin (A) is 65°C or more, it is suitable because the heat-resistant storage property of the toner is improved. When the Tg2nd of the polyester resin (A) is 75°C or less, it is suitable because the low-temperature fixability of the toner is improved.

[0043] The method for measuring the glass transition temperature (Tg) of the polyester resin (A) is not particularly limited. For example, it can be measured 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 the Method for Measuring the Glass Transition Temperature (Tg)- Put 5.0 mg of the polyester resin (A) into an aluminum sample pan, place it on the holder unit, and set it in the electric furnace. As a reference, 10 mg of alumina is used and put into an aluminum sample pan. Under a nitrogen atmosphere, heat from 0 °C at a heating rate of 10 °C / min to 150 °C (the first heating), then cool from 150 °C at a cooling rate of 10 °C / min to 0 °C (the cooling process), and heat again from 0 °C at a heating rate of 10 °C / min to 150 °C (the second heating). Measure the endothermic and exothermic changes in the above process, draw a graph of temperature and endothermic / exothermic amount, create a DSC curve, and perform analysis using the analysis program in the Q-200 system. Select the DSC curve in the second heating, and determine the glass transition temperature of the polyester resin (A) from the intersection of the extension line of the baseline of the DSC curve at a temperature lower than the enthalpy relaxation of the endothermic amount and the tangent line showing the maximum slope in the enthalpy relaxation.

[0044] [Weight-Average Molecular Weight of the Polyester Resin (A)] The weight-average molecular weight (Mw) of the polyester resin (A) in gel permeation chromatography (GPC) measurement is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.8×10 4 or more and 1×10 5 or less, more preferably 1×10 4 or more and 5×10 4 or less. In this specification, "weight-average molecular weight (Mw) in gel permeation chromatography (GPC) measurement" may sometimes be simply referred to as "weight-average molecular weight (Mw)". When the weight-average molecular weight (Mw) of the polyester resin (A) is 0.8×10 4 or more, it is suitable because the mechanical durability of the toner becomes good. When the weight average molecular weight (Mw) of the polyester resin (A) is 5×10 4 or less, it is suitable because the low-temperature fixability of the toner is good.

[0045] There is no particular limitation on the method for measuring the weight average molecular weight (Mw), but it 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 the method for measuring the weight average molecular weight (Mw) - As the column, TSKgel SuperHZM-H 15 cm triple (manufactured by Tosoh Corporation) is used. The polyester resin (A) to be measured is made into a 0.15 mass% solution using tetrahydrofuran (THF) (containing a stabilizer, manufactured by Fujifilm Wako Pure Chemical Corporation), filtered through a 0.2 μm filter, and then the filtrate is used as a sample. 100 μl of the THF sample solution is injected into the measuring device, and measurement is performed at a flow rate of 0.35 ml / min in an environment at a temperature of 40°C. The molecular weight is calculated using a calibration curve prepared with a monodisperse polystyrene standard sample. As the polystyrene standard sample, THF solutions (solutions A to C) of the following three types of monodisperse polystyrene standard samples are prepared using the Showdex STANDARD series manufactured by Showa Denko KK, measured under the above conditions, and a calibration curve is created with the retention time at the peak top as the light scattering molecular weight of the monodisperse polystyrene standard sample. An RI (refractive index) detector is used as the detector. Solution A: S-7300 2.5 mg, S-602 2.5 mg, S-46 2.5 mg, S-2.8 2.5 mg, THF 50 mL Solution B: S-3500 2.5 mg, S-277 2.5 mg, S-18 2.5 mg, S-1.3 2.5 mg, THF 50 mL Solution C: S-1700 2.5 mg, S-136 2.5 mg, S-6.7 2.5 mg, toluene 2.5 mg, THF 50 mL

[0046] <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. There are no particular restrictions on such other resins, and they can be appropriately selected according to the purpose. For example, homopolymers of styrene or its substituents such as polystyrene, poly-p-styrene, polyvinyltoluene, etc., styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-methyl α-chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer, styrene-maleic ester copolymer and other styrene-based copolymers, polythimer 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, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin, etc., and these resins modified to have functional groups capable of reacting with active hydrogen groups such as isocyanate groups, etc. can be mentioned. These other resins may be used alone or in combination of two or more.

[0047] The solid content concentration in the polyester resin emulsion for toner is not particularly limited and can be appropriately selected according to the purpose, but it 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 with respect to the core particles is good, and it is suitable because the productivity of the toner is improved. When the solid content concentration in the polyester resin emulsion for toner is 50% by mass or less, the emulsion stability is good, which is preferable.

[0048] There is no particular limitation on the method for measuring the solid content concentration in the polyester resin emulsion for toner, and it can be appropriately selected according to the purpose. For example, it can be calculated by weighing an emulsion sample on an aluminum cup and drying it in a constant temperature bath set at 150°C for 3 hours, and then weighing the emulsion sample before and after drying.

[0049] Although details will be described later, the polyester resin emulsion for toner is preferably a shell resin emulsion used in the production of toner having a core-shell structure composed of core particles containing a binder resin and shell particles covering the core particles.

[0050] [Method for producing polyester resin emulsion for toner] There is no particular limitation on the method for producing the polyester resin emulsion for toner, and it can be appropriately selected according to the purpose. For example, a shear emulsification method, a phase inversion emulsification method, and other known dispersion methods can be mentioned. As an example of the shear emulsification method, after dissolving the polyester resin (A) in an organic solvent, it is added to an aqueous medium and dispersed by mechanical shear forces such as a homomixer, homogenizer, ball mill having media, sand mill, dynomill, etc. of low-speed shear type, high-speed shear type, friction type, high-pressure jet type, ultrasonic type, etc. As an example of the phase inversion emulsification method, after dissolving the polyester resin (A) in an organic solvent, an aqueous medium is added to cause phase inversion. Among these, from the viewpoint of obtaining a homogeneous emulsion with a sharp particle size distribution, it is preferably produced by the phase inversion emulsification method.

[0051] <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 to cause phase inversion emulsification.

[0052] ―Organic solvent― The organic solvent used in the phase inversion emulsification method is not particularly limited and can be appropriately selected according to the purpose. For example, 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, dichloroethylidene, etc. can be mentioned. Among these, from the viewpoints of solvent removability and solubility of the polyester resin, methyl ethyl ketone, ethyl acetate, and isopropyl acetate are preferable. These may be used alone or in combination of two or more.

[0053] From the viewpoint of dispersion stability, it is preferable to rapidly 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 solvent removal method can be selected according to the purpose. For example, a method of gradually raising the temperature while stirring the emulsion to evaporate and remove the organic solvent in the system, a method of spraying the emulsion into a dry atmosphere such as air or nitrogen while stirring to remove the organic solvent in the system, a method of reducing the pressure while stirring the emulsion to evaporate and remove the organic solvent in the system, etc. can be mentioned. These solvent removal methods may be used alone or in combination of two or more.

[0054] -Aqueous medium- The aqueous medium used in the phase inversion emulsification method is not particularly limited and can be appropriately selected according to the purpose. For example, water, a mixture of water and the above-mentioned organic solvent miscible with water, etc. can be mentioned. The content of the aqueous medium is not particularly limited and can be appropriately selected according to the purpose. It is preferably 80 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the resin solution. In the phase inversion emulsification method, the addition rate of the aqueous medium until the resin solution is phase-inverted and reaches completion is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.1 part by mass / min or more and 60 parts by mass / min or less with respect to 100 parts by mass of the resin solution, and more preferably 1 part by mass / min or more and 3 parts by mass / min or less. When the addition rate of the aqueous medium is 0.1 part by mass / min or more with respect to 100 parts by mass of the resin solution, it is preferable because the productivity of the toner is improved. When the addition rate of the aqueous medium is 60 parts by mass / min or less with respect to 100 parts by mass of the resin solution, the particle size distribution becomes sharp and the cohesiveness of the shell particles with respect to the core particles is good. Therefore, it is suitable because the shell can be formed uniformly.

[0055] In the phase inversion emulsification method, a neutralizing agent, a surfactant, a polymer protective colloid, etc. can be added to the resin solution or the aqueous medium within a range that does not impair the effects of the present invention.

[0056] - Neutralizing agent - The neutralizing agent is not particularly limited and can be appropriately selected according to the purpose. Examples include basic substances. Examples of the basic substance include ammonia, trimethylamine, ethylamine, diethylamine, triethylamine, diethanolamine, triethanolamine, tributylamine, lithium hydroxide, sodium hydroxide, potassium hydroxide, etc. Among these, ammonia and sodium hydroxide are preferably used from the viewpoint of ensuring the quality of the emulsion.

[0057] The neutralization rate (r), which is the molar ratio of the neutralizing agent to the acid value (AV) of the polyester resin (A), is not particularly limited and can be appropriately selected according to the purpose. It is preferably 30% or more and 150% or less, and more preferably 60% or more and 100% or less. When the neutralization rate (r) is 30% or more, phase inversion emulsification tends to proceed, and a uniform particle size emulsion can be obtained, which is suitable. When the neutralization rate (r) is 150% or less, phase inversion emulsification tends to proceed, which is suitable.

[0058] The amount of the neutralizing agent used is not particularly limited and can be appropriately selected according to the purpose. For example, it can be determined by the following formula (1). Here, AV in the following formula represents the acid value (mgKOH / g) of the resin, M represents the amount of the resin used (g), and r represents the neutralization rate (%). Amount of neutralizing agent used (mol / g) = (AV / 56,110) × M × (r / 100) ··· Formula (1)

[0059] - Surfactant - The surfactant is not particularly limited and can be appropriately selected according to the purpose. For example, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, and phosphate esters; amine salt types such as alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines, and quaternary ammonium salt types of 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; alanine, dodecyldi(aminoethyl)glycine, di(octylaminoethyl)glycine, N-alkyl-N,N-dimethylammonium betaine, etc.

[0060] - Polymer protective colloid - The polymer protective colloid is not particularly limited and can be appropriately selected according to the purpose. For example, acids such as acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride; (meth)acrylic monomers containing hydroxyl groups 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 ester, diethylene glycol monomethacrylate ester, glycerin monoacrylate ester, glycerin monomethacrylate ester, N-methylolacrylamide, N-methylolmethacrylamide; vinyl alcohol; ethers with vinyl alcohol such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether; esters of compounds containing a carboxyl group with vinyl alcohol such as vinyl acetate, vinyl propionate, vinyl butyrate; homopolymers or copolymers such as acrylamide, methacrylamide, diacetoneacrylamide, and their methylol compounds; acid chlorides such as acryloyl chloride, methacryloyl chloride; those having a nitrogen atom or its heterocyclic ring such as vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, ethyleneimine; polyoxyethylene-based such as polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl phenyl ester; celluloses such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc. can be mentioned.

[0061] (Resin particles (T) and toner) The resin particles (T) of the present invention are resin particles (T) having a core-shell structure composed of core particles containing a binder resin and shell particles coating the core particles, wherein the shell particles are formed from a polyester resin emulsion for toner, and optionally, external additives and other components may be included. The toner of the present invention is a toner having a core-shell structure composed of core particles containing a binder resin and shell particles coating the core particles, wherein the shell particles are formed from the polyester resin emulsion for toner of the present invention, and optionally, external additives and other components may be included. Note that since the "polyester resin emulsion for toner" is the same as that described in the above item (polyester resin emulsion for toner), the description thereof is omitted. Also, the resin particles (S) contained in the polyester resin emulsion for toner and the resin particles (T) composed of the polyester resin emulsion for toner are different.

[0062] <Core-shell structure> The core-shell structure refers to, for example, (1) a structure in which shell particles made of resin are arranged on the outermost surface of core particles containing a binder resin, and the surface of the core particles is coated with the shell particles, or (2) a structure in which a shell layer made of resin is formed on the outermost surface of core particles containing a binder resin, and the surface of the core particles is coated with the shell layer. In the present invention, the "shell layer" refers to the shell part in a state where the shell particles are fused together by heat treatment of the structure of (1) above and the boundary between the particles becomes unclear. From the viewpoints of excellent homogeneity, heat-resistant storage stability, and mechanical durability of the toner, and being less likely to peel off the shell layer due to stress, the structure of (2) is preferable. Also, in the present invention, the shell part in the core-shell structures of (1) and (2) above may be referred to as the "shell".

[0063] In the resin particles (T) and toner having the core-shell structure, the surface of the core particles does not necessarily have to be completely covered by the shell, but from the viewpoints of toner homogeneity, heat storage stability, and mechanical durability, it is preferable that the coated area is 90% or more of the total surface area of the core particles.

[0064] <<Core particles>> The core particles contain a binder resin, and may contain, as necessary, a crystalline resin as a fixing aid, a colorant, a release agent, a charge control agent, and the like.

[0065] ―Binder resin― The binder resin is not particularly limited and can be appropriately selected according to the purpose. For example, homopolymers of styrene or its substituents such as polystyrene, poly-p-styrene, polyvinyltoluene, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-methyl α-chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer, styrene-maleic acid ester copolymer and other styrene-based copolymers, polythimer 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, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin, etc., and these resins modified to have a functional group capable of reacting with an active hydrogen group such as an isocyanate group. These may be used alone or in combination of two or more.

[0066] From the viewpoint of enhancing the adhesion of the core particles to the shell and obtaining a toner with excellent mechanical durability, it is preferable that the binder resin contains at least one or more amorphous polyester resins (B). The polyester resin in the amorphous polyester resin (B) is not particularly limited and can be appropriately selected according to the purpose. For example, those similar to those described in the item of <<Polyester Resin (A)>> above can be used.

[0067] - Crystalline Resin - The crystalline resin is not particularly limited as long as it has crystallinity and can be appropriately selected according to the purpose. For example, polyester resins, polyurethane resins, polyurea resins, polyamide resins, polyether resins, vinyl resins, modified crystalline resins, etc. can be mentioned. Among these, polyester resins are preferable from the viewpoint of excellent compatibility between low-temperature fixability and heat-resistant storage stability. These may be used alone or in combination of two or more.

[0068] The crystalline resin preferably melts near the fixing temperature of the toner. By containing such a crystalline resin in the toner, at the fixing temperature, it becomes compatible with the binder resin as the crystalline resin melts, improving the sharp meltability of the toner and exerting an effect of excellent low-temperature fixability, which is preferable. The melting point of the crystalline resin is not particularly limited, but it 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 melting of the crystalline resin is likely to occur at a low temperature, and the heat-resistant storage stability of the toner is good, which is suitable. When the melting point of the crystalline resin is 100°C or lower, the low-temperature fixability of the toner is good, which is suitable.

[0069] - Colorant - The coloring agent is not particularly limited and can be appropriately selected according to the purpose. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, loess, lead yellow, 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, anthrazane yellow BGL, isoindolinone yellow, red lead, minium, vermilion, cadmium red, cadmium mercury red, antimony vermilion, permanent red 4R, para red, phthalein red, parachlororthonitroaniline red, resorcin fast scarlet G, brilliant fast scarlet, brilliant carmine BS, permanent red (F2R, F4R, FRL, FRLL, F4RH), fast scarlet VD, Balkan fast rubine B, brilliant scarlet G, resorcin rubine GX, permanent red F5R, brilliant carmine 6B, pigment scarlet 3B, Bordeaux 5B, toluidine maroon, permanent Bordeaux F2K, heliobordeaux 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, alkali blue lake, peacock blue lake, victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, indanthrene blue (RS, BC), indigo, ultramarine, dark blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt violet, manganese violet, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridine, 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 white, lithopone, etc. These may be used alone or in combination of two or more.

[0070] The content of the colorant is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 1% by mass or more and 15% by mass or less, 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. When the content of the colorant is 1% by mass or more based on the total amount of the resin particles (T) or the total amount of the toner, the coloring power of the toner is good, which is preferable. When the content of the colorant is 15% by mass or less based on the total amount of the resin particles (T) or the total amount of the toner, the dispersion state of the pigment in the toner is good, and the coloring power and the charging characteristics of the toner are good, which is preferable.

[0071] The colorant may be used as a masterbatch compounded with a resin for masterbatch. The resin for masterbatch is not particularly limited and can be appropriately selected according to the purpose. For example, polymers of styrene or its substituents, 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, paraffin, etc. may be mentioned. These may be used alone or in combination of two or more.

[0072] - Release agent - The release agent is not particularly limited and can be appropriately selected according to the purpose. For example, 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, stearyl stearate; polyalkanol esters such as tristearyl trimellitate, distearyl maleate; polyalkanoic acid amides such as dibehenyl amide; polyalkyl amides such as tristearyl amide trimellitate; dialkyl ketones such as distearyl ketone; polyolefin waxes such as polyethylene wax, polypropylene wax; waxes such as paraffin wax, microcrystalline wax, sasol wax and other long-chain hydrocarbons. Among these, waxes of alkanoic acid esters are preferred. These may be used alone or in combination of two or more.

[0073] The melting point of the release agent is not particularly limited and can be appropriately selected according to the purpose. Preferably, it is 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. When the melting point of the release agent is 40°C or higher, it is suitable because the heat-resistant storage property is good. When the melting point of the release agent is 160°C or lower, it is suitable because the occurrence of cold offset during low-temperature fixing can be suppressed.

[0074] The content of the release agent is not particularly limited and can be appropriately selected according to the purpose. Preferably, it is 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. When 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, it is suitable because the fluidity of the toner is good.

[0075] - Charge control agent - The charge control agent is not particularly limited and can be appropriately selected according to the purpose. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxyamines, quaternary ammonium salts, alkylamides, simple substances or compounds of phosphorus, simple substances or compounds of tungsten, fluorine-based activators, metal salts of salicylic acid, and metal salts of salicylic acid derivatives can be mentioned.

[0076] The content of the charge control agent is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 0.2 part by mass or more and 5 parts by mass or less, based on 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 based on 100 parts by mass of the resin particles (T) or 100 parts by mass of the toner, the charging characteristics of the toner are good, and it is possible to suppress a decrease in the fluidity of the developer and a decrease in image density, which is preferable.

[0077] [Volume average particle diameter (Dv) of the core particles] The volume average particle diameter (Dv) of the core particles is not particularly limited and can be appropriately selected according to the purpose. From the viewpoints of granularity, sharpness, and fine line reproducibility, it is preferably 4 μm or more and 7 μm or less in median diameter (D50). The method for measuring the median diameter (D50) is not particularly limited and can be appropriately selected according to the purpose. For example, it can be measured using a laser particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.).

[0078] [Average circularity of the core particles] The average circularity of the core particles is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of transfer efficiency, fine line reproducibility, and cleaning property of the toner remaining on the photoreceptor or transfer belt, etc., it is preferably 0.940 or more and 0.990 or less. As a method for measuring the average circularity of the core particles, there is no particular limitation, and it can be appropriately selected according to the purpose. For example, it can be measured using a flow-type particle image analyzer FPIA-3000 (manufactured by SYSMEX Corporation).

[0079] As a method for producing the core particles, there is no particular limitation, and it can be appropriately selected according to the purpose. For example, there are kneading and pulverizing methods, and so-called chemical methods such as granulating particles in an aqueous medium.

[0080] Examples of the chemical method include suspension polymerization, emulsion polymerization, seed polymerization, dispersion polymerization, etc. using monomers as starting materials; dissolution suspension methods in which resins or resin precursors are dissolved in organic solvents and dispersed or emulsified in an aqueous medium; phase inversion emulsion methods in which water is added to a solution composed of a resin or resin precursor and a suitable emulsifier to cause phase inversion; and aggregation methods in which resin particles obtained by these methods are aggregated in a state of being dispersed in an aqueous medium and granulated into particles of a desired size by heating and melting or the like. Among these, the dissolution suspension method, phase inversion emulsion method, and aggregation method, which can easily handle polyester resins and the like with excellent low-temperature fixing properties, are preferable.

[0081] As the core particles, from the viewpoint of aggregating with the polyester resin emulsion for toner, it is preferably an aqueous dispersion, and more preferably an aqueous dispersion of core particles obtained by a chemical method.

[0082] When using core particles obtained by the kneading and pulverizing method, from the viewpoint of forming a uniform shell, it is preferably core particles that have been spheroidized and surface-smoothed by heat treatment or the like.

[0083] From the viewpoint of aggregating shell particles on the surface of the core particles, it is preferably particles to which no external additives or fluidity improvers are added.

[0084] <<Shell>> The shell can be obtained by subjecting the resin particles (S) in the polyester resin emulsion containing the resin particles (S) forming the shell to the steps of aggregating them on the outermost surface of the core particles and then heating and fusing them. It is preferable that the core particles and the shell are in a state of being in close contact with each other or in a state where they are not completely compatible with each other and there are regions consisting of only the core particles or the shell.

[0085] The average thickness of the shell is not particularly limited and can be appropriately selected according to the purpose, but is preferably 50 nm or more and 500 nm or less, and more preferably 100 nm or more and 200 nm or less. When the average thickness of the shell is 50 nm or more, the protective function of the core particles by the shell is improved, and the heat-resistant storage property and mechanical durability are good, which is preferable. When the average thickness of the shell is 500 nm or less, the low-temperature fixability is good, which is preferable.

[0086] The method for measuring the average thickness of the shell is not particularly limited and can be appropriately selected according to the purpose. For example, a sample in which toner particles are embedded in an epoxy resin or the like is cut with a microtome or an ultramicrotome and ultrathin-sectioned, and the ultrathin-sectioned sample can be measured by confirming it with a transmission electron microscope (TEM). At this time, in some cases, it is preferable to stain the ultrathin sections with a staining agent such as ruthenium tetroxide or osmium tetroxide because the core-shell structure becomes easier to visually recognize. Specifically, it is as follows. A sample in which toner particles are embedded in an epoxy resin is ultrathin-sectioned with an ultramicrotome, and the cross-sectional image is photographed at 20,000 times using a TEM (field emission electron microscope JEM-2100F manufactured by JEOL Ltd.). The photographed image is taken into an image analyzer (LuzexAP manufactured by Nireco), and for 30 toner particles, the thickness of the shell is measured 5 times for each particle, and it can be obtained from the average value thereof.

[0087] The volume average particle diameter (Dv) of the resin particles (T) and the toner is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of obtaining a high-quality image with excellent granularity, sharpness, and fine line reproducibility, it is preferably 3 μm or more and 10 μm or less, and more preferably 4 μm or more and 7 μm or less. When 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 good, which is preferable.

[0088] 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. The closer the value is to 1, the sharper the particle size distribution is shown. From the viewpoints of sharpness and fine line reproducibility, the ratio (Dv / Dn) is preferably 1.20 or less, and more preferably 1.15 or less.

[0089] The method for measuring the volume average particle diameter (Dv) and the number average molecular weight (Dn) of the resin particles (T) and the toner is not particularly limited. For example, it can be measured using a Coulter Multisizer III (aperture diameter 100 μm) (manufactured by Beckman Coulter).

[0090] The average circularity of the resin particles (T) and the toner is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.940 or more and 0.990 or less. Further, it is more preferable that 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 an average circularity of less than 0.94 is 15% by mass or less based on the total amount of the resin particles (T) and the toner. Toner particles with an average circularity within the above range, i.e., substantially spherical toner particles, are excellent in transfer efficiency, have an appropriate density, and are effective for forming a high-definition image with reproducibility. Also, they are suitable because a good image with less transfer omission in a fine line image can be obtained. This is presumably because the toner surface is sufficiently smooth, reducing the contact points with the image support and decreasing the problem of worm-eaten transfer failure of the toner onto the transfer material. When the average circularity of the resin particles (T) and the toner is 0.940 or more, it is suitable because the transferability is good. When the average circularity of the resin particles (T) and the toner is 0.990 or less, in a system employing cleaning by a blade or the like, problems such as cleaning failure occurring on the photoreceptor and the transfer belt, and causing dirt on the image, can be solved, making it suitable. For example, in development or transfer with a low image area ratio, there is little residual toner after transfer, and cleaning failure is not particularly a problem. However, in the case of an image with a high image area ratio such as a color photographic image, untransferred toner for forming an image may occur on the photoreceptor as residual toner after transfer due to paper feeding failure or the like, and when this accumulates, background staining of the image occurs. Also, there is a problem that a charging roller or the like that contacts and charges the photoreceptor is contaminated, and the original charging ability cannot be exerted. However, the present invention can solve this problem and is suitable. There is no particular limitation on the method for measuring the average circularity of the toner, and it can be appropriately selected according to the purpose. For example, it can be measured using a flow-type particle image analyzer FPIA - 3000 (manufactured by SYSMEX Corporation).

[0091] There is no particular limitation on the method for measuring the average circularity of the resin particles (T) and the toner, and it can be appropriately selected according to the purpose. For example, it can be measured using a flow-type particle image analyzer FPIA - 3000 (manufactured by SYSMEX Corporation). Specifically, it can be obtained by calculating the circularity from the two-dimensional image area of each particle imaged by a CCD camera, adding up the circularities of each particle, and dividing 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 projection image.

[0092] <External additive> There are no particular restrictions on the external additive, and it can be appropriately selected according to the purpose. Examples include inorganic fine particles, polymer-based fine particles, fluidity improvers, cleaning aids, and the like.

[0093] ―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, cinder, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, and the like.

[0094] There are no particular restrictions on the primary particle diameter of the inorganic fine particles, and it can be appropriately selected according to the purpose. However, it is preferably 5 nm or more and 2 μm or less, and more preferably 5 nm or more and 500 nm or less. When the primary particle diameter of the inorganic fine particles is 5 nm or more, it is possible to suppress the embedding of the toner particles on the surface due to mechanical stress, which is preferable. When the primary particle diameter of the inorganic fine particles is 2 μm or less, it is possible to suppress the detachment from the toner particles, which is preferable. The specific surface area of the inorganic fine particles by the BET method is preferably 20 m 2 / g or more and 500 m 2 / g or less. 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.

[0095] -Polymer-based fine particles- Examples of the polymer-based fine particles include polymer particles obtained by soap-free emulsion polymerization, suspension polymerization, dispersion polymerization, such as polystyrene, methacrylic acid ester, acrylate copolymer, silicone, benzoguanamine, nylon, and other polycondensation-based and thermosetting resin polymers.

[0096] - Fluidity improver - As the fluidity improver, there is no particular limitation as long as it can increase hydrophobicity by surface treatment and prevent deterioration of fluidity characteristics and charging characteristics even under high humidity, and it can be appropriately selected according to the purpose. For example, silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum-based coupling agents, silicone oil, modified silicone oil, etc. can be mentioned. The silica and titanium oxide which are the inorganic fine particles are preferably used as hydrophobic silica and hydrophobic titanium oxide by performing surface treatment with the fluidity improver.

[0097] - 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. For example, fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, polymer fine particles produced by soap-free emulsion polymerization such as polymethyl methacrylate fine particles and polystyrene fine particles, etc. can be mentioned. As the polymer fine particles, those having a relatively narrow particle size distribution are preferable, and those having a volume average particle diameter of 0.01 μm or more and 1 μm or less are suitable.

[0098] The external additive adheres to the particle surface by the step of adding and mixing it to the resin particles (T) and the toner. There is no particular limitation on the mixing method. For example, a method of applying an impact force to the mixture by blades rotating at high speed, a method of introducing the mixture into a high-speed air stream, accelerating it, and causing the particles or the composite particles to collide with an appropriate collision plate, etc. are available. Specifically, as the means for mixing, for example, an Ongmill (manufactured by Hosokawa Micron Corporation), a modified device of the I-type mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) with a reduced pulverizing air pressure, a hybridization system (manufactured by Nara Machinery Co., Ltd.), a cryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), an automatic mortar, etc. can be mentioned.

[0099] [Method for Producing Resin Particles (T) and Toner Having a Core-Shell Structure] The method for producing the resin particles (T) and the toner is not particularly limited. For example, it may include an aggregation step and a fusion step, and may include a washing step, a drying step, and annealing as necessary.

[0100] <Aggregation Step> The aggregation step is a step of adding shell particles to a dispersion of core particles dispersed in an aqueous medium and aggregating the shell particles on the surface of the core particles while stirring.

[0101] The aggregation step may be carried out while heating. The temperature of the aqueous medium in the aggregation step is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of efficiently aggregating, it is preferably 20°C or higher and not higher than the glass transition temperature (Tg) of the polyester resin (A).

[0102] In the aggregation step, an aggregating agent may be added or the pH may be adjusted from the viewpoint of promoting aggregation. The flocculant is not particularly limited and can be appropriately selected according to the purpose. For example, 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, magnesium fluoride, 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, etc. can be mentioned. These may be used alone or in combination of two or more.

[0103] The content of the flocculant is not particularly limited and can be appropriately selected according to the purpose. However, with respect to 100 parts by mass of the total amount of the core particles and the shell particles, 0.1 part by mass or more and 20 parts by mass or less is preferable, and 0.5 part by mass or more and 10 parts by mass or less is more preferable. From the viewpoint of performing uniform aggregation in the reaction system, the flocculant is preferably used as an aqueous solution. 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 with respect to the total amount of the aqueous solution.

[0104] The addition rate of the aggregates to the aqueous medium is not particularly limited and can be appropriately selected according to the purpose. With respect to 100 parts by mass of the aqueous medium containing the core particles and the shell particles, it is preferably 0.1 part by mass / min or more and 5 parts by mass / min or less, and more preferably 0.5 part by mass / min or more and 2 parts by mass / min or less.

[0105] The aggregation reaction in the aggregation step can be stopped as necessary. The method for stopping the aggregation reaction is not particularly limited, and examples thereof include a method of adding a salt with a low ionic valence, a chelating agent, a surfactant, etc., a method of adjusting the pH, a method of lowering the temperature of the dispersion, and a method of adding a large amount of the 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 nitrilotriacetate salts, and polyelectrolytes.

[0106] <Fusing step> The fusing step is a step of heating and fusing the aggregated particles composed of the core particles and the shell particles obtained by the aggregation step to form a shell on the surface of the core particles.

[0107] In the fusing step, it is preferable to heat the dispersion of the aggregated particles while stirring. The temperature in the fusing step is not particularly limited, but it is preferably at or above the glass transition temperature (Tg) of the polyester resin (A).

[0108] <Washing step> The washing step is a step of washing the resin particles (T) and the toner obtained by the fusing step. The method of washing in the washing step is not particularly limited and can be appropriately selected according to the purpose. For example, centrifugation, vacuum filtration, filter press method, etc. can be mentioned. In addition, when washing cannot be sufficiently performed in one operation, the cake obtained by the washing step may be dispersed again in an aqueous solvent to form a slurry, and the step of taking out the resin particles (T) and toner by any of the above methods may be repeated. Further, when washing is performed by a vacuum filtration method or a filter press method, it may be a method of washing by passing an aqueous solvent through the cake. The aqueous solvent used for the washing is not particularly limited, and examples thereof include water or a mixed solvent in which an alcohol such as methanol or ethanol is mixed with water. Among these, water is preferable from the viewpoints of cost and environmental load such as wastewater treatment.

[0109] <Drying step> The drying step is a step of drying the cake body obtained by the washing step. The method of drying in the drying step is not particularly limited and can be appropriately selected according to the purpose. For example, methods of drying using a dryer such as a spray dryer, a vacuum freeze dryer, a vacuum dryer, a stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, a rotary dryer, a stirring dryer, etc. can be mentioned. It is preferable to perform the drying until the water content in the cake body becomes less than 1%. Further, 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 Augusta blender, a hood processor, etc., and operations such as loosening aggregates may be performed.

[0110] <Annealing> The annealing is preferably carried out when the crystalline polyester resin is contained in the core particles. The annealing temperature is preferably in the range of not lower than the glass transition temperature and not higher than the melting point of the crystalline polyester resin. Also, the annealing time is preferably 3 hours or more and 24 hours or less, more preferably 6 hours or more and 15 hours or less.

[0111] <Developer> The toner of the present invention can be used as a developer containing other appropriately selected components such as a carrier. The developer may be a one-component developer or a two-component developer. However, when used in a high-speed printer or the like corresponding to the recent improvement in information processing speed, a two-component developer is preferred because the service life is improved. In the case of a one-component developer using the toner, even if the balance of the toner, that is, the supply of the toner to the developer and the consumption of the toner by development are carried out, the variation in the particle size of the toner is small, and there is no filming of the toner on the developing roller or fusion of the toner to a layer thickness regulating member such as a blade for thinning the toner layer. Even in the long-term use (stirring) of the developing means, good and stable developability and images can be obtained. In the case of the two-component developer using the toner, even if the balance of the toner is carried out over a long period, the variation in the toner particle size in the developer is small, and particularly good charge stability and development stability can be obtained even in the long-term stirring in the developing means.

[0112] The carrier is not particularly limited and can be appropriately selected according to the purpose. However, those having a core material and a resin layer covering the core material are preferred. The material of the core material is not particularly limited and can be appropriately selected according to the purpose. For example, a manganese-strontium (Mn-Sr) -based material or a manganese-magnesium (Mn-Mg) -based material with a magnetization of 50 emu / g or more and 90 emu / g or less is preferred. From the perspective of ensuring image density, high magnetization materials such as iron powder (100 emu / g or more) and magnetite (75 emu / g or more and 120 emu / g or less) are preferred. Also, a weakly magnetized material of a copper-zinc (Cu-Zn) system (30 emu / g or more and 80 emu / g or less) is preferred in that it can weaken the hitting on the electrostatic latent image carrier in a state where the toner is in a standing state and is advantageous for high image quality. These may be used alone or in combination of two or more.

[0113] The particle size of the core material is preferably 10 μm or more and 200 μm or less, more preferably 40 μm or more and 100 μm or less, in terms of the average particle size (weight average particle size (D50)). When the average particle size (weight average particle size (D50)) is 10 μm or more, in the distribution of carrier particles, the amount of fine powder systems increases, and problems such as a decrease in magnetization per particle and carrier scattering can be solved, which is suitable. When the average particle size (weight average particle size (D50)) is 200 μm or less, problems such as toner scattering due to a decrease in specific surface area and particularly poor reproduction of solid parts in full-color with many solid parts can be solved, which is suitable.

[0114] The material of the resin layer is not particularly limited and can be appropriately selected from known resins according to the purpose. For example, amino resins, polyvinyl resins, polystyrene resins, halogenated olefin resins, polyester resins, polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytetrafluoroethylene resins, polyhexafluoropropylene resins, fluorinated terpolymers (fluorinated terpolymers (fluorinated terpolymers)) such as copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, and terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, silicone resins, etc. Among these, silicone resins are preferred. These may be used alone or in combination of two or more.

[0115] The silicone resin is not particularly limited and can be appropriately selected from generally known silicone resins according to the purpose. For example, straight silicone resins composed only of organosiloxane bonds, silicone resins modified with alkyd resins, polyester resins, epoxy resins, acrylic resins, urethane resins, etc. As the silicone resin, those synthesized as appropriate may be used, or commercially available products may be used. Examples of commercially available products of the silicone resin include, for example, as straight silicone resins, KR271, KR255, KR152 manufactured by Shin-Etsu Chemical Co., Ltd., SR2400, SR2406, SR2410 manufactured by Toray Dow Corning Silicone Co., Ltd.

[0116] As the modified silicone resin, those synthesized as appropriate may be used, or commercially available products may be used. Examples of commercially available products of the modified silicone resin include, for example, KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified) manufactured by Shin-Etsu Chemical Co., Ltd., SR2115 (epoxy modified), SR2110 (alkyd modified) manufactured by Toray Dow Corning Silicone Co., Ltd.

[0117] In addition, it is also possible to use the silicone resin alone, or to use components that undergo a cross-linking reaction, charge amount adjustment components, etc. simultaneously.

[0118] The resin layer may contain conductive powder or the like as necessary. Examples of the conductive powder include metal powder, carbon black, titanium oxide, tin oxide, zinc oxide, and the like. From the viewpoint of facilitating the control of electrical resistance, the average particle size of the conductive powder is preferably 1 μm or less.

[0119] For example, the resin layer can be formed by dissolving the silicone resin or the like in a solvent to prepare a coating solution, then uniformly applying the coating solution to the surface of the core material by a known coating method, drying, and then performing baking. Examples of the coating method include dipping method, spraying method, brush coating method, and the like. The solvent is not particularly limited and can be appropriately selected according to the purpose. Examples include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cellosolve, butyl acetate, and the like. The baking is not particularly limited and may be an external heating method or an internal heating method. For example, it may be a method using a stationary electric furnace, a fluidized electric furnace, a rotary electric furnace, a burner furnace, etc., or a method using microwaves.

[0120] The content of the carrier is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.01% by mass or more and 5.0% by mass or less based on the total amount of the resin layer. When the content of the carrier is 0.01% by mass or more based on the total amount of the resin layer, it is possible to form a uniform resin layer on the surface of the core material, which is preferable. When the content of the carrier is 5.0% by mass or less based on the total amount of the resin layer, it is possible to solve problems such as an increase in the thickness of the resin layer, granulation of the carriers with each other, and inability to obtain uniform carrier particles, which is preferable.

[0121] When the developer is a two-component developer, the content of the carrier is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 90% by mass or more and 98% by mass or less, more preferably 93% by mass or more and 97% by mass or less, based on 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 with respect to 100 parts by mass of the carrier.

[0122] [Image Forming Apparatus and Image Forming Method] The image forming apparatus according to the present invention is not particularly limited as long as the toner of the present invention is used, and can be appropriately selected according to the purpose. For example, it includes an electrostatic latent image carrier, an electrostatic latent image forming means, a developing means, and, if necessary, other means. The image forming method according to the present invention is not particularly limited as long as the toner of the present invention is used, and can be appropriately selected according to the purpose. For example, it includes an electrostatic latent image forming step and a developing step, and, if necessary, other steps.

[0123] <Electrostatic Latent Image Carrier> The latent image carrier is not particularly limited in terms of its material, shape, structure, size, etc., and can be appropriately selected from known ones. As the shape, a drum shape is preferably mentioned. As the material, for example, inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors such as polysilane and phthalopolymethine can be mentioned. 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 agent and an electron transport agent can also be added as charge transport materials to the photosensitive layer. Further, an undercoat layer may be provided between the support and the laminated charge generation layer or the single-layer photosensitive layer. The linear velocity of the electrostatic latent image carrier is preferably 300 mm / s or more.

[0124] <Electrostatic Latent Image Forming Means and Electrostatic Latent Image Forming Step> The electrostatic latent image forming means is not particularly limited as long as it is means for forming an electrostatic latent image on the electrostatic latent image carrier, and can be appropriately selected according to the purpose. For example, means having at least a charging member for charging the surface of the electrostatic latent image carrier and an exposure member for imagewise exposing the surface of the electrostatic latent image carrier can be mentioned. The electrostatic latent image forming step is not particularly limited as long as it is a step for forming an electrostatic latent image on the electrostatic latent image carrier, and can be appropriately selected according to the purpose. For example, it can be performed by charging the surface of the electrostatic latent image carrier and then imagewise exposing it, and can be performed using the electrostatic latent image forming means.

[0125] <<Charging Member and Charging>> The charging member is not particularly limited and can be appropriately selected according to the purpose. For example, known contact chargers provided with conductive or semiconductive rollers, brushes, films, rubber blades, etc., non-contact chargers using corona discharge such as corotrons and scorotrons can be mentioned. Among these, it is preferable to use a contact type charging member in terms of obtaining an image forming apparatus in which ozone generated from the charging member is reduced. The shape of the charging member may take any form such as magnetic brushes and fur brushes in addition to rollers, and can be selected according to the specifications and form of the image forming apparatus.

[0126] The charging can be performed, for example, by applying a voltage to the surface of the electrostatic latent image carrier using the charging member.

[0127] <<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 an image-like manner, and can be appropriately selected according to the purpose. For example, 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 can be mentioned.

[0128] The light source used for the exposure member is not particularly limited and can be appropriately selected according to the purpose. For example, various light-emitting substances such as fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light-emitting diodes (LEDs), semiconductor lasers (LDs), and electroluminescence (EL) can be mentioned. In addition, for the light source used for the exposure member, 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 can also be used to irradiate only light in a desired wavelength range.

[0129] The exposure can be performed, for example, by exposing the surface of the electrostatic latent image carrier in an image-like manner using the exposure member. In the present invention, a light backside exposure method in which exposure is performed in an image-like manner from the backside of the electrostatic latent image carrier may be adopted.

[0130] <Developing means and developing process> The developing means is not particularly limited as long as it is a developing means provided with toner for developing the electrostatic latent image formed on the electrostatic latent image carrier to form a toner image which is a visible image, and can be appropriately selected according to the purpose. The developing process is not particularly limited as long as it is a process of forming a toner image which is a visible image by developing the electrostatic latent image formed on the electrostatic latent image carrier using toner, and can be appropriately selected according to the purpose. For example, it can be performed by the developing means. As the developing means, a developing device having an agitator that stirs and rubs the toner to charge it and a magnetic field generating means fixed inside, and having a developer carrier that is rotatable while carrying a developer containing the toner on its surface is preferable.

[0131] <Other means and other processes> Examples of the other means include, for example, transfer means, fixing means, cleaning means, charge elimination means, recycling means, and the like. Examples of the other processes include, for example, a transfer process, a fixing process, a cleaning process, a charge elimination process, a recycling process, and the like.

[0132] <<Transfer means and transfer process>> The transfer means is not particularly limited as long as it is means for transferring a visible image to a recording medium, and can be appropriately selected according to the purpose. However, a mode having first transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image and second transfer means for transferring the composite transfer image onto the recording medium is preferable. The transfer process is not particularly limited as long as it is a process for transferring a visible image to a recording medium, and can be appropriately selected according to the purpose. However, a mode in which an intermediate transfer member is used, a visible image is first transferred onto the intermediate transfer member, and then the visible image is secondarily transferred onto the recording medium is preferable. The transfer process can be performed, for example, by charging the photoreceptor using a transfer charger, and can be performed by the transfer means.

[0133] Here, when the image secondarily transferred onto the recording medium is a color image composed of a plurality of colors of toner, by the transfer means, the toners of each color are sequentially superimposed on the intermediate transfer member to form an image on the intermediate transfer member, and by the intermediate transfer means, the image on the intermediate transfer member can be secondarily transferred onto the recording medium in a batch. The intermediate transfer member is not particularly limited and can be appropriately selected from known transfer members according to the purpose. For example, a transfer belt and the like are preferably mentioned.

[0134] In addition, in this embodiment, an elastic intermediate transfer belt can also be used as the intermediate transfer member. As the elastic intermediate transfer belt, for example, a belt obtained by laminating a flexible elastic layer on a rigid base layer that can obtain relatively good flexibility can be used. Also, in order to prevent the intermediate transfer member from meandering, a retaining guide member may be provided on the inner peripheral surface of the intermediate transfer member.

[0135] The transfer means (the first transfer means and the second transfer means) preferably includes at least a transfer device that peels and charges the visible image formed on the photoreceptor toward the recording medium side. Examples of the transfer device include a corona transfer device by corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, an adhesive transfer device, and the like. Typically, the recording medium is plain paper, but there is no particular limitation as long as it can transfer the unfixed image after development, and it can be appropriately selected according to the purpose. For example, a PET base for OHP can also be used.

[0136] <<Fixing means and fixing process>> The fixing means is not particularly limited as long as it is a means for fixing the transferred image on the recording medium, and can be appropriately selected according to the purpose. For example, a known heating and pressure member is preferable. Examples of the heating and pressure member include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt, and the like. The fixing process is not particularly limited as long as it is a process for fixing the visible image transferred to the recording medium, and can be appropriately selected according to the purpose. For example, it may be performed each time the toner of each color is transferred to the recording medium, or it may be performed simultaneously at once in a stacked state for the toner of each color. The fixing process can be performed by the fixing means. The heating in the heating and pressure member is preferably 80°C to 200°C.

[0137] In the present invention, depending on the purpose, instead of or together with the fixing means, for example, a known light fixing device may be used. The surface pressure in the fixing step is not particularly limited and can be appropriately selected according to the purpose, but it is preferably 2 10 N / cm 2 to 80 N / cm.

[0138] <<Cleaning means and cleaning step>> The cleaning means is not particularly limited as long as it can remove the toner remaining on the photoreceptor, and can be appropriately selected according to the purpose. For example, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, a brush cleaner, a web cleaner, etc. can be mentioned. The cleaning step is not particularly limited as long as it can remove the toner remaining on the photoreceptor, and can be appropriately selected according to the purpose. For example, it can be performed by the cleaning means.

[0139] <<Charge removing means and charge removing step>> The charge removing means is not particularly limited as long as it applies a charge removing bias to the photoreceptor for charge removal, and can be appropriately selected according to the purpose. For example, a charge removing lamp can be mentioned. The charge removing step is not particularly limited as long as it applies a charge removing bias to the photoreceptor for charge removal, and can be appropriately selected according to the purpose. For example, it can be performed by the charge removing means.

[0140] <<Recycling means and recycling step>> The recycling means is not particularly limited as long as it recycles the toner removed in the cleaning step to the developing device, and can be appropriately selected according to the purpose. For example, known conveying means can be mentioned. The recycling step is not particularly limited as long as it is a step of recycling the toner removed in the cleaning step to the developing device, and can be appropriately selected according to the purpose. For example, it can be performed by the recycling means.

[0141] Here, the 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 embodiments shown below, and can be changed within the scope that those skilled in the art can conceive, such as other embodiments, additions, modifications, deletions, etc. As long as the functions and effects of the present invention are achieved in any aspect, it is included in the scope of the present invention.

[0142] One aspect of implementing a method of forming an image by the image forming apparatus of the present invention will be described with reference to FIG. 1. Note that although a printer is shown as an example of the image forming apparatus of the present embodiment, the image forming apparatus of the present invention is not particularly limited as long as it can form an image using toner, such as a copying machine, a facsimile machine, a multifunction machine, etc.

[0143] FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention. The image forming apparatus includes a paper feeding unit 210, a conveying unit 220, an image forming unit 230, a transfer unit 240, and a fixing unit 250. The paper feeding unit 210 includes a paper feeding cassette 211 on which the paper P to be fed is stacked, and a paper feeding roller 212 that feeds the paper P stacked in the paper feeding cassette 211 one by one.

[0144] The conveying unit 220 includes a roller 221 that conveys the paper P fed by the paper feeding roller 212 in the direction of the transfer unit 240, a pair of timing rollers 222 that sandwich the leading end of the paper P conveyed by the roller 221 and wait, and send the paper to the transfer unit 240 at a predetermined timing, and a paper discharge roller 223 that discharges the paper P on which the color toner image is fixed to the paper discharge tray 224.

[0145] The image forming section 230 includes, at a predetermined interval, an image forming unit 180Y that forms an image using a developer containing yellow toner, an image forming unit 180C that forms an image using a developer containing cyan toner, an image forming unit 180M that forms an image using a developer containing magenta toner, an image forming unit 180K that forms an image using a developer containing black toner, and an exposure unit 233, in order from left to right in FIG. 1.

[0146] The image forming units 180 (180Y, 180C, 180M, 180K) are provided rotatably clockwise in FIG. 1, and include a photosensitive drum 231 (231Y, 231C, 231M, 231K) on which an electrostatic latent image and a toner image are formed, a charger 232 (232Y, 232C, 232M, 232K) that uniformly charges the surface of the photosensitive drum 231 (231Y, 231C, 231M, 231K), and a cleaner 236 (236Y, 236C, 236M, 236K) that removes toner remaining on the surface of the photosensitive drum 231 (231Y, 231C, 231M, 231K).

[0147] The image forming units 180 (180Y, 180C, 180M, 180K) include a toner bottle 234 (234Y, 234C, 234M, 234K) that stores toner of each color, and a sub hopper 160 (160Y, 160C, 160M, 160K) that replenishes toner supplied from the toner bottle 234 (234Y, 234C, 234M, 234K).

[0148] Note that when any one of the image forming units 180 (180Y, 180C, 180M, 180K) is indicated, it is referred to as an image forming unit.

[0149] The exposure unit 233 reflects laser light L emitted from a light source 233a based on image information by a polygon mirror 233b (233bY, 233bC, 233bM, 233bK) rotationally driven by a motor, and irradiates the photosensitive drum 231. Further, the developer has toner and carrier. The four image forming units 180 (180Y, 180C, 180M, 180K) are substantially identical in mechanical configuration, differing only in the developer used for each.

[0150] The transfer unit 240 includes a driving roller 241 and a driven roller 242, an intermediate transfer belt 243 that can rotate counterclockwise in FIG. 1 as the driving roller 241 is driven, and a primary transfer roller 244 (244Y, 244C, 244M, 244K) provided to face the photosensitive drum 231 (231Y, 231C, 231M, 231K) with the intermediate transfer belt 243 interposed therebetween, and a secondary opposing roller 245 and a secondary transfer roller 246 provided to face each other with the intermediate transfer belt 243 interposed therebetween at the transfer position of the toner image onto the paper.

[0151] The fixing device 250 has a heater provided therein, and includes a fixing belt 251 for heating the paper P, and a pressure roller 252 that forms a nip by rotatably pressing against the fixing belt 251. Thereby, heat and pressure are applied 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 is fixed is discharged to the discharge tray 224 by the discharge roller 223, and a series of image forming processes is completed.

Example

[0152] Hereinafter, examples and comparative examples of the present invention will be described, but the present invention is not limited to these examples in any way. Also, in the following description, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0153] First, each measurement method will be described.

[0154] [Measurement of Glass Transition Temperature (Tg) and Melting Point] The glass transition temperature (Tg) of the resin was measured using a differential scanning calorimeter (DSC) Q-200 (manufactured by TA Instruments). 5.0 mg of the resin sample was placed in an aluminum sample pan, mounted on a holder unit, and set in an electric furnace. As a reference, 10 mg of alumina (aluminum oxide, manufactured by Fuji Film Wako Pure Chemical Corporation) was used, which was placed in an aluminum sample pan in the same manner as the sample. Under a nitrogen atmosphere, it was heated from 0 °C to 150 °C at a heating rate of 10 °C / min (the first heating), then cooled from 150 °C to 0 °C at a cooling rate of 10 °C / min (the cooling process), and then heated again from 0 °C to 150 °C at a heating rate of 10 °C / min (the second heating). The endothermic and exothermic changes during the above process were measured, a graph of temperature versus endothermic and exothermic amounts was drawn, and a DSC curve was obtained. The obtained DSC curve was analyzed using the analysis program in the Q-200 system. The second heating DSC curve was selected, and the glass transition temperature of the resin sample was 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 amount and the tangent line showing the maximum slope in the enthalpy relaxation. Similarly, the second heating DSC curve was selected, and the peak temperature of the endothermic amount was taken as the melting point of the crystalline resin or wax sample.

[0155] [Measurement of weight average molecular weight (Mw)] The weight average molecular weight (Mw) of the resin was measured using a gel permeation chromatography (GPC) measuring device HLC-8220GPC (manufactured by Tosoh Corporation). As the column, a TSKgel SuperHZM-H 15 cm triple column (manufactured by Tosoh Corporation) was used. The resin to be measured was made into a 0.15% solution with tetrahydrofuran (THF) (containing a stabilizer, manufactured by Fujifilm Wako Pure Chemical Corporation), filtered through a 0.2 μm filter, and the filtrate was used as a sample. 100 μl of the THF sample solution was injected into the measuring device and measured at a flow rate of 0.35 ml / min in an environment at a temperature of 40°C. The molecular weight was calculated using a calibration curve created with a monodisperse polystyrene standard sample. As the polystyrene standard sample, THF solutions (solutions A to C) of the following three types of monodisperse polystyrene standard samples were prepared using the Showdex STANDARD series manufactured by Showa Denko K.K., measured under the above conditions, and a calibration curve was created with the retention time at the peak top as the light scattering molecular weight of the monodisperse polystyrene standard sample. An RI (refractive index) detector was used as the detector. · Solution A: 2.5 mg of S-7300, 2.5 mg of S-602, 2.5 mg of S-46, 2.5 mg of S-2.8, 50 mL of THF · Solution B: 2.5 mg of S-3500, 2.5 mg of S-277, 2.5 mg of S-18, 2.5 mg of S-1.3, 50 mL of THF · Solution C: 2.5 mg of S-1700, 2.5 mg of S-136, 2.5 mg of S-6.7, 2.5 mg of toluene, 50 mL of THF

[0156] [Measurement of acid value (AV) and hydroxyl value (OHV)] The acid value (AV) and hydroxyl value (OHV) of the resin were measured by the method specified in JIS K0070. The measurement solvent for the acid value was a mixed solvent of acetone (manufactured by Fujifilm Wako Pure Chemical Corporation), methanol (manufactured by Fujifilm Wako Pure Chemical Corporation), and toluene (manufactured by Fujifilm Wako Pure Chemical Corporation) (acetone: methanol: toluene = 12.5: 12.5: 75), and the measurement solvent for the hydroxyl value was tetrahydrofuran (THF) (manufactured by Fujifilm Wako Pure Chemical Corporation).

[0157] [Measurement of volume average particle size (Dv)] The volume average particle diameter (Dv) of the resin particles and toner was measured using a Coulter Multisizer III (aperture diameter 100 μm, manufactured by Beckman Coulter, Inc.) and analysis software Beckman Coulter Multisizer 3 (version 3.51, manufactured by Beckman Coulter, Inc.). 10 mg of the measurement sample was added to 5 mL of a 10% surfactant (alkylbenzene sulfonate, Neogen SC-A, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and dispersed for 1 minute using an ultrasonic disperser. Then, an arbitrary amount of 25 mL of isotonic III (manufactured by Beckman Coulter, Inc.), which is an electrolyte, was added and dispersed for 1 minute using an ultrasonic disperser to prepare a sample dispersion. Next, an appropriate amount of 100 mL of the electrolyte and the sample dispersion were added to a beaker, and 30,000 particles were measured at a concentration at which the particle diameters of 30,000 particles could be measured in 20 seconds, and the volume average particle diameter (Dv) was determined from the particle size distribution.

[0158] [Average circularity, and amount of fine powder of 2 μm or less] The average circularity of the resin particles and toner, and the amount of fine powder of 2 μm or less were measured using a flow-type particle image analyzer FPIA-3000 (manufactured by SYSMEX CORPORATION). After preparing a 1% NaCl aqueous solution using primary sodium chloride (manufactured by Fujifilm Wako Pure Chemical Corporation), 0.1 to 5 mL of alkylbenzene sulfonate (Neogen, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as a dispersant was added to 50 to 100 mL of the solution passed through a 0.45 μm filter, and 1 to 10 mg of the sample was added. This was subjected to a dispersion treatment for 1 minute using an ultrasonic disperser, and the measurement was performed using a dispersion adjusted to a particle concentration of 5000 to 15000 particles / μL.

[0159] (Production Examples 1 to 22 of Polyester Resin (A)) -Production of Polyester Resins (A-1) to (A-22)- In a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen inlet pipe, the raw material A shown in Tables 1-1 and 1-2 was charged so that the molar ratio of the hydroxyl group to the carboxylic acid group (OH / COOH) was 1.2. Further, tetrabutoxytitanate (titanium dihydroxybis(triethanolamine), manufactured by Tokyo Chemical Industry Co., Ltd.) as a condensation catalyst was charged at 1,000 ppm based on the total monomer amount. The temperature was raised to 200°C over 2 hours under a nitrogen stream, and then further raised to 230°C over 8 hours, and the reaction was carried out for 5 hours while distilling off the generated water. Thereafter, the reaction was carried out for 1 hour under a reduced pressure of 5 mmHg to 15 mmHg, and after cooling to 200°C, trimellitic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) in the amounts shown in Tables 1-1 and 1-2 was added, and the reaction was carried out at 200°C for 1 hour at normal pressure, and then the reaction was carried out under a reduced pressure of 5 mmHg to 20 mmHg until the desired molecular weight was reached to obtain [polyester resin (A-1) to (A-22)] which is a polyester resin (A). The obtained [polyester resin (A-1) to (A-22)] was measured for glass transition point (Tg), weight average molecular weight, acid value (AV), hydroxyl value (OHV), and ratio (OHV / AV), and the results are shown in Tables 1-1 and 1-2.

[0160] (Production Example 1 of Polyester Resin Emulsion) - Production of Polyester Resin Emulsion (EM-1)- Into a 500 ml separable flask equipped with a stirrer, 150 parts of [polyester resin (A-1)] and 150 parts of methyl ethyl ketone (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were put, and further sodium hydroxide (0.3N) (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was charged at 80% equivalent of the neutralization rate with respect to the acid value of [polyester resin (A-1)] to prepare a resin mixture. Next, while stirring the resin mixture, 400 parts of ion-exchanged water was gradually added to carry out phase inversion emulsification. Thereafter, the solvent was removed while reducing the pressure with an evaporator, and ion-exchanged water was added so that the solid content concentration became 25% to obtain [polyester resin emulsion (EM-1)].

[0161] (Production Examples 2 to 22 of Polyester Resin Emulsion) Regarding [Polyester Resin (A-2) to (A-22)] as well, the same treatment was carried out as in Production Example 1 of the polyester resin emulsion to obtain [Polyester Resin Emulsion (EM-2) to (EM-22)].

[0162] For the obtained [Polyester Resin Emulsion (EM-1) to (EM-22)], the median diameter (D50) was measured, and the results are shown in Table 2.

[0163] (Production Example of Amorphous Polyester Resin (B)) -Production of Amorphous Polyester Resin (B)- Into a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen inlet pipe, the acid monomers and alcohol monomers shown in Table 1 were charged so that the molar ratio of hydroxyl group to carboxylic acid (OH / COOH) was 1.2. Further, tetrabutoxytitanate was added as a condensation catalyst at 1,000 ppm based on the total monomer amount. The temperature was raised to 200°C over 2 hours under a nitrogen stream, and then further raised to 230°C over 8 hours, and reacted for 5 hours while distilling off the generated water. Thereafter, it was reacted for 1 hour under a reduced pressure of 5 mmHg to 15 mmHg, cooled to 200°C, then pyromellitic dianhydride was added in the amount shown in Table 4, reacted at 200°C under normal pressure for 1 hour, and then further reacted under a reduced pressure of 5 mmHg to 20 mmHg until the desired molecular weight was reached to obtain [Amorphous Polyester Resin (B)], which is an amorphous polyester resin (B). For the obtained [Amorphous Polyester Resin (B)], the glass transition point (Tg), weight average molecular weight, acid value (AV), and hydroxyl value (OHV) were measured, and the results are shown in Table 1-2.

[0164] (Production Example of Crystalline Polyester Resin) -Production of Crystalline Polyester Resin (C)- Into a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen inlet pipe, 1,6 - hexanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) and sebacic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) as the dicarboxylic acid component were charged so that the molar ratio of hydroxyl group to carboxylic acid (OH / COOH) was 1.1. Further, titanium dihydroxybis(triethanolaminato) (manufactured by Tokyo Chemical Industry Co., Ltd.) as a condensation catalyst was added at 500 ppm based on the total monomer amount. The temperature was raised to 180°C over 2 hours under a nitrogen stream, and the reaction was carried out for 8 hours while distilling off the generated water. Then, while gradually raising the temperature to 220°C, the reaction was carried out for 5 hours while distilling off the generated water under a nitrogen stream. Further, under a reduced pressure of 5 mmHg to 20 mmHg, [crystalline polyester resin (C)] with a melting point of 68°C, an acid value of 10.5 mgKOH / g, and a weight - average molecular weight of 11,000 was obtained.

[0165] (Production Example 1 of Crystalline Polyester Resin Dispersion) - Production of Crystalline Polyester Resin Dispersion (C - 1) Into a reaction vessel equipped with a cooling pipe, a thermometer, and a stirrer, 10 parts of [crystalline polyester resin (C)] and 90 parts of ethyl acetate (manufactured by Fujifilm Wako Pure Chemical Corporation) were put, heated to 77°C and dissolved sufficiently, and then cooled to 30°C over 1 hour while stirring. Thereafter, it was wet - ground with an Ultraviscomill (manufactured by Imex) under the conditions of a liquid - feeding rate of 1.0 Kg / hr, a disk peripheral speed of 10 m / sec, a zirconia bead filling amount of 80% by volume, and 6 passes. Ethyl acetate was added to adjust the solid content concentration to 10%, and [crystalline polyester resin dispersion (C - 1)] with a median diameter (D50) of 0.3 μm measured by a laser - type particle size distribution measuring device LA - 920 (manufactured by Horiba, Ltd.) was obtained.

[0166] (Production Example 2 of Crystalline Polyester Resin Dispersion) - Production of Crystalline Polyester Resin Dispersion (C - 2) Into a 500 ml separable flask equipped with a stirrer, 150 parts of [crystalline polyester resin (C)], 75 parts of methyl ethyl ketone (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), and 75 parts of isopropyl alcohol (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were added. After heating to 65 °C and dissolving, an aqueous ammonia solution (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was further added in an amount equivalent to 60% of the acid value of [crystalline polyester resin (C)] to prepare a resin mixture. Next, while stirring the resin mixture at 65 °C, 400 parts of ion-exchanged water were gradually added to perform phase inversion emulsification. Thereafter, the solvent was removed while reducing the pressure with an evaporator, and ion-exchanged water was added so that the solid content concentration became 25%, to obtain [crystalline polyester resin dispersion (C-2)] composed of a crystalline polyester resin emulsion having a median diameter (D50) of 0.3 μm.

[0167] (Production Example of Colorant Masterbatch) -Manufacture of Colorant Masterbatch (MB)- 100 parts of [amorphous polyester resin (B)], 100 parts of a cyan pigment (Pigment Blue 15:3), and 50 parts of ion-exchanged water were thoroughly mixed and kneaded with an open roll kneader (manufactured by Nidex / Mitsui Mining Co., Ltd.). The kneading temperature was 80 °C, and then the temperature was raised to 120 °C to remove water, to obtain [colorant masterbatch (MB)] in which the ratio (mass ratio) of the resin to the pigment was 1:1.

[0168] (Production Example of Colorant Dispersion) 30 parts of a cyan pigment (Pigment Blue 15:3), 3 parts of an anionic surfactant (sodium linear alkylbenzene sulfonate (Neogen), manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and 67 parts of ion-exchanged water were placed in a container and dispersed at 6,000 rpm for 30 minutes with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). Next, using a high-pressure disperser Altimizer (Starburst, manufactured by Sugino Machine Ltd.), a dispersion treatment was performed at a pressure of 245 MPa for 20 passes. Thereafter, ion-exchanged water was added so that the solid content concentration became 25% to obtain [colorant dispersion].

[0169] (Production Example 1 of Wax Dispersion) - Production of Wax Dispersion (W-1)- Into a reaction vessel equipped with a cooling pipe, a thermometer, and a stirrer, 20 parts of an ester wax (WE-11, manufactured by NOF Corporation) with a melting point of 70°C and 80 parts of ethyl acetate were placed. The mixture was heated to 77°C and dissolved thoroughly, and then cooled to 30°C over 1 hour while stirring. Thereafter, it was wet-milled using an Ultraviscomill (manufactured by Imex) under the conditions of a liquid feeding rate of 1.0 Kg / hr, a disk peripheral speed of 10 m / sec, a zirconia bead filling amount of 80% by volume, and 6 passes. Ethyl acetate was added to adjust the solid content concentration to 20%, and [Wax Dispersion (W-1)] with a median diameter (D50) of 0.6 μm measured by a laser particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.) was obtained.

[0170] (Production Example 2 of Wax Dispersion) - Production of Wax Dispersion (W-2)- Into a container, 30 parts of an ester wax (WE-11, manufactured by NOF Corporation) with a melting point of 70°C, 2 parts of an anionic surfactant (sodium linear alkylbenzene sulfonate (Neogen), manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and 68 parts of ion-exchanged water were placed. While cooling the container with ice water, it was dispersed at 8,000 rpm for 2 hours using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). Thereafter, ion-exchanged water was added so that the solid content concentration became 25%, and [Wax Dispersion (W-2)] with a median diameter (D50) of 0.6 μm measured by a laser particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.) was obtained.

[0171] (Production Example 1 of Core Particle Dispersion) - Production of Core Particle Dispersion (CR-1) by Dissolution Suspension Method- In a container equipped with a stirrer and a thermometer, 68 parts of ion-exchanged water, 1 part of sodium carboxymethyl cellulose (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 16 parts of a 48% aqueous solution of sodium dodecyl diphenyl ether disulfonic acid (Eremol MON-7, manufactured by Sanyo Chemical Industries, Ltd.), and 5 parts of ethyl acetate were mixed and stirred. Further, 10 parts of an emulsion for particle size control composed of a copolymer of sodium styrene-methacrylic acid-butyl acrylate-ethylene oxide adduct sulfate (solid content concentration: 20%, median diameter: 50 nm, manufactured by Sanyo Chemical Industries, Ltd.) was added to prepare an [aqueous phase solution].

[0172] Next, 76 parts of [amorphous polyester resin (B)], 60 parts of [crystalline polyester resin dispersion (C-1)], 30 parts of [wax dispersion (W-1)], and 12 parts of [colorant masterbatch (MB)] were placed in another container equipped with a stirrer and a thermometer. Ethyl acetate was added so that the solid content concentration became 50%, and the mixture was stirred and dissolved thoroughly. Then, using a TK type homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), it was dispersed at a rotational speed of 8,000 rpm for 2 hours to be uniformly dissolved and dispersed to prepare an [oil phase].

[0173] 50 parts of the [oil phase] was added to the container containing 75 parts of the [aqueous phase solution], and they were mixed at a rotational speed of 12,000 rpm for 1 minute with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at a liquid temperature of 30°C to 40°C to obtain an emulsified slurry. The obtained emulsified slurry was transferred to another container equipped with a stirrer, a nitrogen introduction tube, and a thermometer. While stirring, the temperature was raised to 50°C, and ethyl acetate was distilled off under a nitrogen stream. Next, a 10% aqueous sodium hydroxide solution (manufactured by Fujifilm Wako Pure Chemical Corporation) was added to adjust the pH of the emulsified slurry to 12, and then it was heated at 45°C for 10 hours to dissolve and remove the emulsion for particle size control adhering to the particle surface of the emulsified slurry, and suction filtration was performed to obtain a solid content. The obtained solid content was subjected to a washing process in which reslurrying was performed with 40 times the equivalent amount of ion-exchanged water based on the mass of the solid content, and the operation of filtering after sufficient stirring was performed twice. After that, ion-exchanged water was added to the solid content again to obtain a [core particle dispersion (CR-1)] adjusted to a solid content concentration of 25%. The obtained [core particle dispersion (CR-1)] was measured for volume average particle size and average circularity, and the results are shown in Table 3.

[0174] (Production Example 2 of Core Particle Dispersion) -Production of Core Particle Dispersion (CR-2) by Emulsion Aggregation Method- Into a container equipped with a stirrer, 150 parts of [amorphous polyester resin (B)] and 150 parts of methyl ethyl ketone were placed, and further 70% equivalent of sodium hydroxide (0.3N) based on the acid value of [amorphous polyester resin (B)] was added to prepare a resin mixture. Next, while stirring the resin mixture, 400 parts of ion-exchanged water were gradually added to perform phase inversion emulsification. Then, while reducing the pressure with an evaporator, the solvent was removed, ion-exchanged water was added so that the solid content concentration became 25%, and an [amorphous polyester resin (B) emulsion] having a median diameter (D50) of 0.2 μm measured by a laser particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.) was obtained. Next, into another container equipped with a stirrer and a thermometer, 328 parts of [amorphous polyester resin (B) emulsion], 24 parts of [crystalline polyester resin dispersion (C-2)], 24 parts of [wax dispersion (W-2)], and 24 parts of [colorant dispersion] were placed. While stirring, 20 parts of a 20% aqueous magnesium sulfate solution (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were added dropwise at 2 parts / min, and then the temperature was raised to 55°C. Then, when the volume average particle size (Dv) of the emulsion reached 5 μm, 120 parts of a 10% aqueous sodium chloride solution (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were added, the temperature was raised to 60°C, stirred for 1 hour, cooled to room temperature, and ion-exchanged water was added to obtain [core particle dispersion (CR-2)] adjusted to a solid content concentration of 25%. The obtained [core particle dispersion (CR-2)] was measured for volume average particle size and average circularity, and the results are shown in Table 3.

[0175] (Production Example 3 of Core Particle Dispersion) -Production of Core Particle Dispersion (CR-3) by Melt Kneading Method- 76 parts of [amorphous polyester resin (B)], 6 parts of [crystalline polyester resin (C)], 6 parts of ester wax (WE-11, manufactured by NOF Corporation) with a melting point of 70 °C, and 12 parts of [colorant masterbatch (MB)] were preliminarily mixed using a Henschel mixer (FM10B, manufactured by Mitsui Miike Chemical Machinery Co., Ltd.), and then melted and kneaded at 85 °C using a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation). After cooling the obtained kneaded product to room temperature, it was coarsely pulverized to 200 μm - 300 μm using a hammer mill. Next, using a counter jet mill (200AFG, manufactured by Hosokawa Micron Corporation), it was finely pulverized while appropriately adjusting the pulverizing air pressure so that the weight average particle diameter became 5.6 ± 0.3 μm, and then classified using an air classifier (MDS-I, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) while appropriately adjusting the louver opening so that the weight average particle diameter became 6.0 ± 0.2 μm and the amount of fine powder of 4 μm or less was 10% or less by number to obtain [classified particles]. Next, 25 parts of [classified particles], 73 parts of ion-exchanged water, and 2 parts of an anionic surfactant (sodium linear alkylbenzene sulfonate (Neogen), manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were put into another container equipped with a stirrer and stirred thoroughly to obtain [core particle dispersion liquid (CR-3)] adjusted to a solid content concentration of 25%. The obtained [core particle dispersion liquid (CR-3)] was measured for volume average particle diameter and average circularity, and the results are shown in Table 3.

[0176] (Manufacturing Example of Carrier) 5,000 parts of Mn ferrite particles (weight average particle diameter: 35 μm) as the core material were used. A coating liquid prepared by dispersing 300 parts of toluene (manufactured by FUJIFILM Wako Pure Chemical Corporation), 300 parts of butyl cellosolve (manufactured by FUJIFILM Wako Pure Chemical Corporation), 60 parts of an acrylic resin solution (composition ratio methacrylic acid: methyl methacrylate: 2-hydroxyethyl acrylate = 5:9:3, 50% solid content toluene solution, Tg 38 °C), 15 mass of an N-tetramethoxymethylbenzoguanamine resin solution (degree of polymerization 1.5, 77% solid content toluene solution), and 15 mass of alumina particles (average primary particle diameter 0.30 μm) with a stirrer for 10 minutes was used. It was put into a coating apparatus that coats while forming a swirling flow by providing a rotary bottom plate disk and stirring blades in a fluidized bed, and the coating liquid was applied onto the core material. The obtained coated product was fired in an electric furnace under the conditions of 220 °C for 2 hours to obtain a [carrier].

[0177] <Example 1> -Manufacture of resin particles (T) or toner- Into a container equipped with a stirrer and a thermometer, 320 parts of [core particle dispersion liquid (CR-1)] (solid content concentration 25%) and 80 parts of [polyester resin emulsion (EM-1)] (solid content concentration 25%) were put, and while stirring, a 20% aqueous magnesium sulfate solution was slowly dropped at a rate of 1 part / minute, and the dropping was continued until the core particles in the system stopped Brownian motion as observed with an optical microscope. Then, the temperature was raised to 55 °C and stirred for 30 minutes. Then, 100 parts of a 10% aqueous sodium chloride solution was added, the temperature was raised to 70 °C, and stirring operation was carried out at 70 °C until the average circularity reached 0.970. Next, the container was transferred to an ice water bath and cooled to room temperature, and suction filtration was performed to obtain a solid content. To the obtained solid content, 800 parts of ion-exchanged water was added, stirred and reslurried, and then suction filtration to obtain a solid content was repeated 5 times. Then, it was dried at 45 °C for 48 hours in a circulating air dryer. Then, it was sieved with a 75 μm mesh opening to obtain [resin particles (T-1)] which are resin particles (T).

[0178] To 100 parts of the obtained [resin particles (T-1)], 1.0 part of hydrophobic silica (HDK-2000, manufactured by Wacker Chemie AG) and 0.3 part of titanium oxide (MT-150AI, manufactured by Teika Co., Ltd.) were mixed using a Henschel mixer, and then sieved with a 25 μm mesh opening to obtain [toner (TN-1)]. The obtained toner was measured for volume average particle diameter (Dv) and average circularity, and the results are shown in Table 4.

[0179] -Evaluation of shell uniformity- [Resin particles (T-1)] were embedded in a commercially available epoxy resin (S-31, manufactured by DEVCON) and cured, and then ultrathin sectioned with a diamond knife using an ultrasonic ultramicrotome (Leica EM UC7, manufactured by Leica). The thickness of the sections was adjusted to around 100 nm using the interference color of the epoxy resin. Further, the sections were placed on a copper grid mesh and subjected to vapor staining using a 5% aqueous solution of commercially available ruthenium tetroxide (manufactured by Fujifilm Wako Pure Chemical Corporation). Observation was carried out using a transmission electron microscope (JEM-2100F, manufactured by JEOL Ltd.), and an image of the cross-section of the resin particles in the sections was recorded. The cross-section of the toner particles with a shell formed is determined by whether or not the crystalline polyester resin, wax, and colorant are exposed on the particle surface, that is, whether or not these components are exposed on the outermost surface of the resin particles. Specifically, for 30 arbitrarily selected resin particles, the surface of the resin particles in the cross-sectional image was observed, and the ratio (P) of the number of particles with no exposure of the crystalline polyester resin, wax, and colorant was determined. The higher the ratio (P), the higher the uniformity of the aggregation state among the shell particles. Evaluation was carried out based on the following evaluation criteria, and the results are shown in Table 4. 〔Evaluation Criteria〕 ◎: Ratio (P) is 90% or more ○: Ratio (P) is 80% or more and less than 90% △: Ratio (P) is 60% or more and less than 80% ×: Ratio (P) is less than 60%

[0180] -Manufacture of Developer- 7 parts of [toner (TN-1)] were uniformly mixed with 100 parts of [carrier] at 48 rpm for 5 minutes using a turbular mixer (manufactured by Willy E. Bachofen (WAB)) of a type in which the container rolls and is stirred to obtain a two-component developer [developer (D-1)].

[0181] -Evaluation of Mechanical Durability of Toner- The developing unit of the digital color multifunction printer RICOH IM C5500 (manufactured by Ricoh Company, Ltd.) was loaded with [developer (D-1)]. After performing 30,000 sheets of blank paper printing in monochrome mode and extracting the developer, an appropriate amount was placed in a gauge with a 32 μm mesh aperture, and air blowing was performed to separate the toner and the carrier. Next, 10 g of the obtained carrier was placed in a 50 ml glass bottle, 10 ml of methyl ethyl ketone was added, and it was shaken 50 times and allowed to stand for 10 minutes. Then, the supernatant methyl ethyl ketone solution was put into a glass cell, and the transmittance of the methyl ethyl ketone solution was measured using a turbidimeter. Evaluation was performed based on the following evaluation criteria, and the results are shown in Table 4. 〔Evaluation Criteria〕 ◎: Transmittance is 95% or more ○: Transmittance is 90% or more and less than 95% △: Transmittance is 80% or more and less than 90% ×: Transmittance is less than 80%

[0182] -Evaluation of Toner Charge Stability- The developing unit of the digital color multifunction printer RICOH IM C5500 (manufactured by Ricoh Company, Ltd.) was loaded with [developer (D-1)]. In monochrome mode, an image chart with an image area ratio of 5% was output on A4 mylar recycled paper 100 (manufactured by NBS Ricoh) in the A4 horizontal direction at a cycle of 5 sheets per job. Every time 100,000 sheets were output, the charge amount of the carrier was measured, and a total of 700,000 sheets of running output were performed. For the charge amount of the carrier, first, the sampled two-component developer was put into a 650-mesh blow-off gauge, and air blowing was performed at an air pressure of 5 KPa for 3 minutes. Then, it was measured using a Q / M meter (manufactured by EPPING) of Epping Co., Ltd. As the settings of the Q / M meter, the mesh size is 650 mesh (stainless steel), and the soft probe blow pressure (1050 V) suction time is 90 seconds. The charge amount is calculated from the following formula (1). Formula (1) Charge amount (μC / g) = Total charge amount (μC) after 90 seconds / Amount of toner sucked (g) At the amount of charge obtained in this way, the charge fluctuation width was evaluated as the difference between the carrier charge amount immediately after the start of running and the maximum and minimum values of the carrier charge amount over time during running. The closer the charge fluctuation width is to zero, the better the charge stability.

[0183] (Initial fog evaluation) The developing unit of the digital color multifunction printer RICOH IM C5500 (manufactured by Ricoh Company, Ltd.) was loaded with [developer (D-1)]. In an environment of 10°C (humidity 15RH%), in monochrome mode, an image chart with an image area ratio of 5% was continuously output 100 sheets in the A4 horizontal direction on A4 mylar recycle paper 100 (manufactured by NBS Ricoh). Then, a fine line image of 600 dpi was output on type 6000 paper (manufactured by NBS Ricoh), and the image density of the non-image area was measured with a colorimeter X-Rite938 (manufactured by X-Rite). The evaluation criteria are shown below. 〔Evaluation criteria〕 ◎: Image density is less than 0.003 ○: Image density is 0.003 or more and less than 0.010 △: Image density is 0.010 or more and less than 0.015 ×: Image density is 0.015 or more and less than 0.030 ××: Image density is 0.030 or more

[0184] (Fog evaluation over time) After 700,000 sheets of running were completed in the charge stability evaluation, in an environment of 10°C (humidity 15RH%), in monochrome mode, a fine line image of 600 dpi was output in the A4 horizontal direction on type 6000 paper (manufactured by NBS Ricoh), and the image density of the non-image area was measured with a colorimeter X-Rite938 (manufactured by X-Rite). The evaluation criteria are shown below. 〔Evaluation criteria〕 ◎: Image density is less than 0.003 ○: Image density is 0.003 or more and less than 0.010 △: Image density is 0.010 or more and less than 0.015 ×: Image density is 0.015 or more and less than 0.030 ××: Image density is 0.030 or more

[0185] <Examples 2 to 16 and Comparative Examples 1 to 8> Resin particles (T-2) to (T-24), toners (TN-2) to (TN-24), and developers (D-2) to (D-24) were obtained in the same manner as in Example 1, except that the combinations of [core particle dispersions (CR-1) to (CR-3)] and [polyester resin emulsions (EM-1) to (EM-22)] shown in Tables 6 to 10 were changed. Each evaluation was performed in the same manner as in Example 1, and the results are shown in Table 4.

[0186]

Table 1-1

[0187]

Table 1-2

[0188]

Table 2

[0189]

Table 3

[0190]

Table 4

[0191] As aspects of the present invention, for example, they are as follows. (1) A polyester resin emulsion for toner in which resin particles (S) containing a polyester resin (A) obtained by polycondensing an alcohol component and a carboxylic acid component are dispersed in an aqueous medium, The alcohol component includes a trivalent or tetravalent alcohol having a straight-chain or branched aliphatic saturated hydrocarbon having 4 to 6 carbon atoms as a skeleton, When the acid value of the polyester resin (A) is AV (mgKOH / g) and the hydroxyl value of the polyester resin (A) is OHV (mgKOH / g), OHV / AV is 0.30 or more and 1.00 or less, and the AV is 10 mgKOH / g or more and 25 mgKOH / g, The polyester resin (A) contains 40% by mass or more and 70% by mass or less of repeating units derived from polyethylene terephthalate (PET) composed of a condensate of terephthalic acid and ethylene glycol. A polyester resin emulsion for toner, characterized in that. (2) The polyester resin emulsion for toner according to (1) above, wherein the alcohol component of the polyester resin (A) contains trimethylolpropane. (3) A resin emulsion for shell formation used in the production of a toner having a core-shell structure composed of core particles containing a binder resin and a shell covering the core particles, which is the polyester resin emulsion for toner according to (1) or (2) above. (4) The polyester resin emulsion for toner according to (3) above, wherein the binder resin contains an amorphous polyester resin (B). (5) The polyester resin emulsion for toner according to any one of (1) to (4) above, wherein the alcohol component contains at least one selected from 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol in an amount of 30 mol% or more based on the total amount of the alcohol component. (6) The polyester resin emulsion for toner according to any one of (1) to (5) above, wherein the glass transition temperature (Tg) in the second heating in differential scanning calorimetry (DSC) of the resin particles (S) is 65°C or more and 75°C or less. (7) A method for producing resin particles having a core-shell structure composed of core particles containing a binder resin and a shell covering the core particles, characterized by including 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 dissolved or dispersed product (2) Suspending the dissolved or dispersed matter in an aqueous medium to form a core particle dispersion liquid (3) Adding the toner polyester resin emulsion according to any one of (1) to (6) above to the core particle dispersion liquid to form a shell on the surface of the core particles (4) Removing the organic solvent (8) A method for manufacturing a toner having a core-shell structure composed of core particles containing a binder resin and a shell covering the core particles, characterized by including at least the following steps (1) to (4). (1) Dissolving or dispersing at least a polyester resin and a release agent in an organic solvent to obtain a dissolved or dispersed matter (2) Suspending the dissolved or dispersed matter in an aqueous medium to form a core particle dispersion liquid (3) Adding the toner polyester resin emulsion according to any one of (1) to (6) above to the core particle dispersion liquid to form a shell on the surface of the core particles (4) Removing the organic solvent

Explanation of symbols

[0192] 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 feeding unit 211 Paper feeding cassette 212 Paper feeding roller 220 Conveying unit 221 Roller 222 Timing roller 223 Discharging roller 224 Discharging tray 230 Image forming 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 unit 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 Cleaner (Yellow) 236C Cleaner (Cyan) 236M Cleaner (Magenta) 236K Cleaner (Black) 240 Transfer section 241 Driving 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 Fuser 251 Fusing belt 252 Pressure roller L Laser Paper P

Prior Art Documents

Patent Documents

[0193]

Patent Document 1

Claims

1. A polyester resin emulsion for toner, wherein resin particles (S) containing a polyester resin (A) obtained by polycondensing an alcohol component and a carboxylic acid component are dispersed in an aqueous medium, the alcohol component contains a trivalent or tetravalent alcohol having a straight-chain or branched aliphatic saturated hydrocarbon having 4 to 6 carbon atoms as a skeleton, when the acid value of the polyester resin (A) is AV (mgKOH / g) and the hydroxyl value of the polyester resin (A) is OHV (mgKOH / g), OHV / AV is 0.30 or more and 1.00 or less, and the AV is 10 mgKOH / g or more and 25 mgKOH / g, the polyester resin (A) contains 40% by mass or more and 70% by mass or less of repeating units derived from polyethylene terephthalate (PET) which is a condensate of terephthalic acid and ethylene glycol, A polyester resin emulsion for toner, characterized by the above.

2. The polyester resin emulsion for toner according to claim 1, wherein the alcohol component of the polyester resin (A) contains trimethylolpropane.

3. A resin emulsion for shell formation used in the production of toner having a core-shell structure composed of core particles containing a binder resin and a shell covering the core particles, which is the polyester resin emulsion for toner according to claim 1 or 2.

4. The polyester resin emulsion for toner according to claim 3, wherein the binder resin contains an amorphous polyester resin (B).

5. The polyester resin emulsion for toner according to claim 1 or 2, wherein the alcohol component contains at least one selected from 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol in an amount of 30 mol% or more based on the total amount of the alcohol component.

6. The polyester resin emulsion for toner according to claim 1 or 2, wherein the glass transition temperature (Tg) in the second heating in differential scanning calorimetry (DSC) of the resin particles (S) is 65°C or more and 75°C or less.

7. A method for producing resin particles having a core-shell structure composed of core particles containing a binder resin and a shell covering the core particles, characterized by including 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 generate a core particle dispersion (3) A step of adding the toner polyester resin emulsion according to claim 1 or 2 to the core particle dispersion to form a shell on the surface of the core particles (4) A step of removing the organic solvent

8. A method for manufacturing a toner having a core-shell structure comprising core particles containing a binder resin and a shell covering the core particles, the method for manufacturing a toner being characterized by including 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 generate a core particle dispersion (3) A step of adding the toner polyester resin emulsion according to claim 1 or 2 to the core particle dispersion to form a shell on the surface of the core particles (4) A step of removing the organic solvent

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