JP6493301B2 - Toner for developing electrostatic latent image and method for producing the same - Google Patents

Description

  The present invention relates to an electrostatic latent image developing toner and a method for producing the same.

  Patent Document 1 describes a toner including a toner core containing a styrene-acrylic acid-based modified polyester resin and shell particles mainly composed of a styrene-acrylic acid resin that covers the toner core. In this toner, the styrene-acrylic acid component of the toner core and the styrene-acrylic acid component of the shell particle are partially compatible to fix the shell particle to the surface layer of the toner core. The shell particles are fixed to the surface layer of the toner core, whereby irregularities are formed on the surface of the toner particles.

JP2013-11644A

  However, in the toner described in Patent Document 1, it is considered that stress is likely to concentrate on the convex portions formed on the surface of the toner particles. Further, when the compatibility between the resin constituting the toner core and the resin constituting the shell particle is high, it is considered that the convex portion is easily embedded in the surface of the toner particle. For this reason, the electrostatic latent image developing toner capable of forming an image having an appropriate image density over a long period of time while achieving both low-temperature fixability and heat-resistant storage stability only with the technique described in Patent Document 1. It is difficult to provide.

  The present invention has been made in view of the above-described problems, and is an electrostatic latent image capable of forming an image having an appropriate image density over a long period of time while achieving both low-temperature fixability and heat-resistant storage stability. An object is to provide a developing toner and a method for producing the same.

The electrostatic latent image developing toner of the present invention includes a plurality of toner particles having a toner core and a shell layer covering the surface of the toner core. The shell layer includes a plurality of first shell particles and a plurality of second shell particles. The first shell particles cover the toner core. The second shell particles further coat the toner core coated with the first shell particles. The coverage (C _F ) by the first shell particles satisfies the following formula (1). The coverage (C _S ) by the second shell particles satisfies the following formula (2). The solubility parameter (SP _T ) of the toner core, the solubility parameter (SP _F ) of the first shell particles, and the solubility parameter (SP _S ) of the second shell particles satisfy the following formula (3).
25% ≦ C _F ≦ 50% (1)
5% ≦ C _S ≦ 30% (2)
SP _T > SP _F > SP _S (3)

  The method for producing the toner for developing an electrostatic latent image of the present invention is the method for producing the toner for developing an electrostatic latent image described above. The method for producing a toner for developing an electrostatic latent image of the present invention includes forming a shell layer on the surface of the toner core. Forming the shell layer includes attaching the first shell particles to the surface of the toner core so as to satisfy the formula (1), and forming the shell layer so as to satisfy the formula (2). Adhering the second shell particles to the surface of the toner core to which the first shell particles are adhered by mixing the adhered toner core and the second shell particles in a dry process.

  According to the present invention, there is provided a toner for developing an electrostatic latent image, which can form an image having an appropriate image density over a long period of time while achieving both low-temperature fixability and heat-resistant storage stability, and a method for producing the same. be able to.

FIG. 3 is a diagram illustrating an example of a cross-sectional structure of toner particles (particularly, toner mother particles) included in the electrostatic latent image developing toner according to the embodiment of the present invention. FIG. 2 is an enlarged view showing a part of the surface of toner base particles shown in FIG. 1.

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, although description may be abbreviate | omitted suitably, the summary of invention is not limited.

  The electrostatic latent image developing toner according to the present embodiment (hereinafter sometimes referred to as “toner”) is a powder composed of a large number of toner particles. The toner particles contained in the toner according to the present embodiment have a toner core and a shell layer formed on the surface of the toner core. An external additive may adhere to the surface of the shell layer. If not necessary, the external additive may be omitted. Hereinafter, the toner particles before the external additive adheres may be referred to as toner mother particles. A material for forming the shell layer is referred to as a shell material. The toner according to the exemplary embodiment can be used in, for example, an electrophotographic apparatus (image forming apparatus).

  In the image forming apparatus, the electrostatic latent image is developed using a developer containing toner. For example, when the image forming apparatus employs an intermediate transfer method, in the developing process, charged toner is attached to the electrostatic latent image formed on the photoconductor to form a toner image. In the subsequent transfer step, after the toner image is transferred to an intermediate transfer member (for example, an intermediate transfer belt), the toner image on the intermediate transfer member is further transferred to a recording medium (for example, paper). Thereafter, the toner image is heated to fix the toner image on the recording medium. As a result, an image is formed on the recording medium. For example, a full color image can be formed by superposing four color toner images of black, yellow, magenta, and cyan.

  In the toner according to this embodiment, the toner particles have a toner core and a shell layer. Hereinafter, an example of the configuration of toner particles (specifically, toner mother particles) contained in the toner according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a cross-sectional structure of toner particles contained in the toner according to the present embodiment. A toner base particle 10 shown in FIG. 1 includes a toner core 11 and a shell layer 12 that covers the surface of the toner core 11. The toner core 11 is partially covered with the shell layer 12, and a part of the surface of the toner core 11 is exposed.

  Next, the state where the shell layer 12 covers the toner core 11 will be described with reference to FIG. FIG. 2 is an enlarged view showing a part of the surface of the toner base particle 10 shown in FIG. The shell layer 12 includes a plurality of first shell particles 12a and a plurality of second shell particles 12b. The first shell particles 12 a cover the toner core 11. The second shell particles 12b further coat the toner core 11 covered with the first shell particles 12a. The second shell particles 12b adhere to the first shell particles 12a. Further, the second shell particles 12 b may adhere to the surface of the toner core 11.

  The shell layer 12 is considered to have a form in which a plurality of first shell particles 12a and a plurality of second shell particles 12b are two-dimensionally connected. The plurality of first shell particles 12a and the plurality of second shell particles 12b may be in contact with each other or may be separated from each other. Examples of the form in contact with each other include a form in physical contact and a form in which the contact surface is melted and fused.

The toner according to this embodiment has the following configuration (1).
Configuration (1) The first shell particles cover the toner core. The second shell particles further coat the toner core coated with the first shell particles. The coverage (C _F ) by the first shell particles satisfies the following formula (1). The coverage (C _S ) by the second shell particles satisfies the following formula (2). The solubility parameter (SP _T ) of the toner core, the solubility parameter (SP _F ) of the first shell particles, and the solubility parameter (SP _S ) of the second shell particles satisfy the following formula (3).
25% ≦ C _F ≦ 50% (1)
5% ≦ C _S ≦ 30% (2)
SP _T > SP _F > SP _S (3)

C _F is the ratio of the area of the first shell particles coated with the toner core to the total area of the toner core coated with the first shell particles. C _S is the ratio of the area of the second shell particles present on the surface of the toner particles to the total area of the toner particles. C _F and C _S can be obtained based on a reflected electron image obtained by a scanning electron microscope (for example, “JSM-7600F” by JEOL Ltd.). Details of the measurement methods of C _F and C _S will be described later. C _F can also be measured after applying the second shell particles to the toner particles. For example, the toner particles having the second shell particles may be measured, and the coverage (C _F ) of only the first shell particles may be obtained without the influence of the second shell particles. Alternatively, the second shell particles may be removed from the toner particles, and C _F may be measured.

The solubility parameter (SP value) is a characteristic value that serves as an index of compatibility. The SP value is represented by the square root of the cohesive energy density (CED). CED is the amount of energy required to evaporate 1 mL of molecules. Hereinafter, based on the following document A and document B, the calculation method of SP value is demonstrated.
Reference A: R.M. F. Fedors, “Polymer Engineering and Science”, 1974, Vol. 14, No. 2, p147-154
Reference B: Akira Imoto, “Basic Theory of Adhesion”, Polymer Publishing Society, 1993

The SP value is represented by the formula “SP value = (E / V) ^1/2 ” (E: molecular cohesive energy [unit: cal / mol], V: molecular volume [unit: cm ³ / mol]). E (molecular cohesive energy) in the formula is represented by the formula “E = ΣΔei” (Δei: evaporation energy of atomic group). V (molecular volume) in the formula is represented by the formula “V = ΣΔvi” (Δvi: molar volume of atomic group). The SP value can be calculated using Fedors' evaporation energy value (see Document A) and the data of Δei and Δvi described in Document B. For example, when calculating SP _T , the atomic groups associated with each of Δei and Δvi correspond to atomic groups included in the binder resin that constitutes the toner core.

Hereinafter, a method for adjusting the SP value (specifically, SP _T , SP _F , or SP _S ) will be described. The SP value of the resin tends to decrease as the hydrophobicity of the resin (resin constituting the toner core, the first shell particle, or the second shell particle) increases, and the SP value of the resin tends to increase as the hydrophilicity of the resin increases. . The SP value of the resin can be adjusted by, for example, introducing a substituent or a crosslinked structure into the resin, or changing the ratio of the repeating unit in the resin. When a substituent is introduced into the resin, the SP value of the resin can be adjusted depending on the type of substituent to be introduced or the number of substituents to be introduced. For example, by introducing a hydrophobic substituent into the resin, the SP value of the resin can be lowered. Examples of the hydrophobic substituent include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group. Moreover, the SP value of the resin can be increased by introducing a hydrophilic substituent into the resin. Examples of the hydrophilic substituent include a hydroxyl group, a carboxyl group, a cyano group, a nitro group, and an amino group.

  Moreover, SP value of resin can be made low by introduce | transducing a crosslinked structure into resin. Examples of the crosslinking agent for introducing a crosslinked structure include a crosslinking monomer. Examples of the crosslinkable monomer include divinylbenzene crosslinkable monomers, diallyl phthalate crosslinkable monomers, and dimethacrylate crosslinkable monomers. Examples of the divinylbenzene-based crosslinking monomer include o-divinylbenzene, m-divinylbenzene, or p-divinylbenzene. Examples of the diallyl phthalate-based crosslinking monomer include diallyl isophthalate and diallyl orthophthalate. Examples of the dimethacrylic acid ester-based crosslinking monomer include ethylene glycol dimethacrylate or triethylene glycol dimethacrylate.

  Moreover, when resin is a copolymer, SP value of resin can be adjusted by changing the ratio of 2 or more types of repeating units contained in resin. For example, the SP value of the resin can be lowered by increasing the proportion of hydrophobic repeating units in the resin. Moreover, SP value of resin can be made high by increasing the ratio of the hydrophilic repeating unit in resin. For example, when the resin is a styrene-acrylic acid resin, increasing the proportion of repeating units derived from styrene monomers decreases the SP value of the resin, and increasing the proportion of repeating units derived from acrylic monomers. The SP value of the resin increases.

The toner having the configuration (1) satisfies the formula (3). By satisfying the relationship of “SP _T > SP _F > SP _S ”, the adhesion force of the first shell particles to the toner core becomes stronger than the adhesion force of the second shell particles to the toner core, and the second shell particles to the first shell particles. Is considered to be stronger than the adhesion force of the second shell particles to the toner core. For this reason, it is considered that the first shell particles are more likely to adhere to the toner core than the second shell particles. Further, it is considered that the second shell particles are more easily attached to the first shell particles than the toner core.

Configuration (1) is useful for achieving both low-temperature fixability and heat-resistant storage stability of the toner. Specifically, it is considered that the first shell particles and the second shell particles each cover the toner core, so that aggregation of the toner particles can be suppressed and the heat resistant storage stability of the toner can be improved. However, if the coverage of the shell particles is too high, there is a risk that sufficient low-temperature fixability of the toner cannot be ensured. In the toner having the configuration (1), C _F is 25% or more and 50% or less, and C _s is 5% or more and 30% or less. The inventors have found that such toners having C _F and C _s are excellent in low-temperature fixability and heat-resistant storage stability. By covering the toner core with the second shell particle as a layer outside the first shell particle, it becomes easy to ensure sufficient heat-resistant storage stability of the toner even when the coverage (C _F ) of the first shell particle is reduced. . Further, by reducing the coverage (C _F ) of the first shell particles, it becomes easy to ensure sufficient low-temperature fixability of the toner. The adhesion force of the second shell particles to the toner core is weaker than the adhesion force of the first shell particles to the toner core. For this reason, when the toner is fixed, the second shell particles are easily detached from the toner particles. For this reason, in the fixing process, the toner is likely to melt and spread at the nip portion. According to the configuration (1), the low-temperature fixability and heat-resistant storage stability of the toner are more easily adjusted than the adjustment of the film thickness of the single shell layer to achieve both low-temperature fixability and heat-resistant storage stability of the toner. It is possible to achieve both. In order to further achieve both low-temperature fixability and heat-resistant storage stability of the toner, C _F is preferably 30% or more and 45% or less, and C _S is preferably 10% or more and 25% or less.

  By forming an image using the toner having the configuration (1), it is possible to form an image having an appropriate image density over a long period of time. The toner having the configuration (1) satisfies the formula (3). Therefore, when an image is formed using toner, it is considered that the first shell particles and the second shell particles are less likely to be detached from the surface of the toner particles until the fixing step. In addition, it is considered that the decrease in image density due to the occurrence of filming (for example, the adhesion of shell particles to the developing roller, the photoreceptor, or the carrier) is suppressed by suppressing the detachment of the shell particles. Therefore, it is considered that an image having an appropriate image density can be formed over a long period of time by using the toner having the configuration (1).

  Moreover, when a crosslinked structure is introduced into the resin constituting the shell particles (specifically, the first shell particles or the second shell particles), the hardness of the shell particles tends to increase. When the hardness of the shell particles is increased, filming is less likely to occur even when the shell particles are detached from the toner particles due to external stress.

In order to improve the adhesion of the first shell particles to the toner core, SP _T and SP _F preferably satisfy the following formula (4), and | SP _T −SP _F | is 0.4 or less. More preferably. When SP _T and SP _F satisfy the formula (4), the first shell particles are easily fixed to the surface of the toner core, and the first shell particles are less likely to be detached from the toner particles. Furthermore, in order to improve the adhesion of the second shell particles to the first shell particles, SP _F and SP _S preferably satisfy the following formula (5), and | SP _F −SP _S | More preferably, it is 4 or less. When SP _F and SP _S satisfy the formula (5), the second shell particles are easily fixed to the first shell particles covering the toner core, and the second shell particles are not easily detached from the toner particles. By suppressing the detachment of the shell particles, filming can be suppressed. In the present specification, the number average particle diameter means the number average primary particle diameter.
| SP _T −SP _F | ≦ 1.0 (4)
| SP _F −SP _S | ≦ 1.0 (5)

  The adhesion force between particles (specifically, between two types of particles selected from the toner core, the first shell particles, and the second shell particles) also varies depending on the particle size (for example, the number average particle size) of these particles. . Hereinafter, a suitable number average particle diameter of each particle will be described. The number average particle diameter is a number average value of equivalent circle diameters (a diameter of a circle having the same area as the projected area of the particles) of a considerable number of particles. The number average particle diameter can be measured by photographing these particles using a transmission electron microscope (TEM).

  In order to suppress filming, the number average particle diameter of the first shell particles and the number average particle diameter of the second shell particles are 0.005 times to 0.04 times each of the number average particle diameter of the toner core. It is preferable that The number average particle diameter of the first shell particles is preferably smaller than the number average particle diameter of the second shell particles. If the number average particle size of the first shell particles is smaller than the number average particle size of the second shell particles, it is easy to achieve both low temperature fixability and heat resistant storage stability of the toner.

  In order to improve the charging stability and low-temperature fixability of the toner, the number average particle diameter of the first shell particles is preferably 30 nm or more and 90 nm or less, more preferably 30 nm or more and 80 nm or less, and more preferably 30 nm or more. More preferably, it is 50 nm or less. When the number average particle diameter of the first shell particles is 30 nm or more, the amount of the surfactant used can be reduced in the production of the first shell particles. By reducing the amount of the surfactant used, it is possible to suppress a decrease in charging stability of the toner due to the surfactant. Further, when the number average particle diameter of the first shell particles is 90 nm or less (preferably 80 nm or less, more preferably 50 nm or less), the low-temperature fixability of the toner tends to be excellent. This is presumably because heat is easily transmitted to the toner core when fixing the toner.

  In order to improve the charging stability of the toner, the number average particle diameter of the second shell particles is preferably 70 nm or more and 300 nm or less, and more preferably 70 nm or more and 150 nm or less. When the number average particle diameter of the second shell particles is 70 nm or more, the hardness of the second shell particles tends to increase. By increasing the hardness of the second shell particles, it is possible to prevent the adhesion force between the second shell particles and the toner core from becoming too strong. Further, when the number average particle diameter of the second shell particles is 300 nm or less, the second shell particles are hardly detached from the toner particles.

  The toner may be used as a one-component developer. Further, a two-component developer may be prepared by mixing toner with a desired carrier.

  Hereinafter, the toner core, the shell layer, and the external additive will be described. Acrylic and methacrylic are sometimes collectively referred to as “(meth) acrylic”. In addition, a compound and a derivative thereof may be generically named by adding “system” after the compound name. When the name of a polymer is expressed by adding “system” after the compound name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

[Toner core]
The toner core includes a binder resin. The toner core may contain an internal additive (for example, a colorant, a release agent, a charge control agent, or a magnetic powder) in addition to the binder resin. Hereinafter, the binder resin, the colorant, the release agent, the charge control agent, and the magnetic powder will be described.

(Binder resin)
In the toner core, generally, the binder resin occupies most of the components (for example, 85% by mass or more). For this reason, it is considered that the properties of the binder resin greatly affect the properties of the entire toner core. For example, when the binder resin has an ester group, a hydroxyl group, an ether group, an acid group (more specifically, a carboxyl group or the like), or a methyl group, the toner core has a strong tendency to become anionic and the binder When the resin has an amino group or an amide group, the toner core tends to become cationic. In order for the binder resin to have a strong anionic property, the hydroxyl value (measurement method: JIS (Japanese Industrial Standard) K0070-1992) and acid value (measurement method: JIS (Japanese Industrial Standard) K0070-1992)) of the binder resin are required. Are each preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more. Further, an anionic compound (for example, a compound having an ester group, a hydroxyl group, an ether group, an acid group, or a methyl group) may be added to the toner core to impart anionicity to the toner core. Alternatively, a cationic compound (for example, a compound having an amino group or an amide group (more specifically, an amine)) may be added to the toner core to impart cationicity to the toner core.

  The binder resin is preferably a resin having one or more functional groups selected from the group consisting of an ester group, a hydroxyl group, an ether group, an acid group (more specifically, a carboxyl group) and a methyl group. And / or a resin having a carboxyl group is more preferred. The binder resin having such a functional group easily reacts with the material of the shell layer to be chemically bonded. When such a chemical bond occurs, the bond between the toner core and the shell layer becomes strong. Further, as the binder resin, a resin having a functional group containing active hydrogen in the molecule is also preferable.

  In order to improve the adhesion between the toner core and the shell layer, it is preferable that the charging polarity of the toner core and the charging polarity of the shell layer have opposite polarities. Examples of the reverse polarity include an embodiment in which the toner core has an anionic property and the shell layer (more specifically, the first shell particle or the second shell particle) has a cationic property. For example, anionicity can be imparted to the toner core by introducing the above-mentioned anionic functional group or mixing the above-mentioned anionic compound. A zeta potential can be used as an indicator of anionic and cationic magnitudes. For example, when the zeta potential of a particle (more specifically, a toner core or the like) measured in an aqueous medium at 25 ° C. adjusted to pH 4 shows less than 0 mV, the particle has an anionic property. For example, a value (preferably +5 mV or more) in which the zeta potential of particles (more specifically, first shell particles etc.) measured in an aqueous medium at 25 ° C. adjusted to pH 4 exceeds 0 mV. Where indicated, the particles are cationic. In this embodiment, pH 4 corresponds to the pH of the toner core dispersion (aqueous medium) when the shell layer is formed. The zeta potential can be suitably measured by, for example, electrophoresis, ultrasonic method, or ESA (electroacoustic) method.

  In order to achieve both low temperature fixability and heat resistant storage stability of the toner, the glass transition point (Tg) of the binder resin is 25 ° C. or higher and 45 ° C. or lower (more preferably 30 ° C. or higher and 40 ° C. or lower). The softening point (Tm) of the binder resin is preferably 70 ° C. or higher and 100 ° C. or lower. The measuring method of Tg and Tm is the same method as the Example mentioned later, respectively, or its alternative method.

The volume median diameter (D ₅₀ ) of the toner core is preferably 5 μm or more and 8 μm or less. When the volume median diameter of the toner core is 5 μm or more and 8 μm or less, it is easy to achieve both low-temperature fixability and heat-resistant storage stability of the toner. The volume median diameter (D ₅₀ ) can be measured using “Coulter Counter Multisizer 3” manufactured by Beckman Coulter, Inc.

  As the binder resin, a thermoplastic resin is preferable. Preferable examples of the thermoplastic resin that can be used as the binder resin include a styrene resin, an acrylic acid resin, an olefin resin (more specifically, a polyethylene resin or a polypropylene resin), a vinyl resin (more specifically, Specifically, vinyl chloride resin, polyvinyl alcohol resin, vinyl ether resin, or N-vinyl resin), polyester resin, polyamide resin, urethane resin, styrene-acrylic acid resin, or styrene-butadiene resin can be used. Among these thermoplastic resins, the polyester resin is excellent in the dispersibility of the colorant in the toner core, the charging property of the toner, and the fixing property of the toner to the recording medium.

  Hereinafter, the polyester resin that can be used as the binder resin will be described. The polyester resin can be obtained by polycondensation or copolycondensation of a divalent or trivalent or higher alcohol and a divalent or trivalent or higher carboxylic acid.

  Examples of dihydric alcohols that can be used to prepare the polyester resin include diols or bisphenols.

  Suitable examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 2-butene-1,4-diol, 1 , 5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene glycol.

  Preferable examples of bisphenols include bisphenol A, hydrogenated bisphenol A, polyoxyethylene bisphenol A, or polyoxypropylene bisphenol A.

  Suitable examples of trihydric or higher alcohols that can be used to prepare the polyester resin include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, Tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, Examples include trimethylolpropane or 1,3,5-trihydroxymethylbenzene.

  Suitable examples of divalent carboxylic acids that can be used to prepare the polyester resin include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, Adipic acid, sebacic acid, azelaic acid, malonic acid, succinic acid, alkyl succinic acid (more specifically, n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, or isododecyl succinic acid) Acid) or alkenyl succinic acid (specifically, n-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid, or isododecenyl succinic acid, etc.).

  Preferable examples of the trivalent or higher carboxylic acid that can be used for preparing the polyester resin include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1 , 2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2, Examples include 4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or empole trimer acid.

  The divalent or trivalent or higher carboxylic acid may be used as an ester-forming derivative (for example, acid halide, acid anhydride, or lower alkyl ester). Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  When preparing the polyester resin, the acid value and hydroxyl value of the polyester resin can be adjusted by changing the amount of alcohol used and the amount of carboxylic acid used. When the molecular weight of the polyester resin is increased, the acid value and hydroxyl value of the polyester resin tend to decrease.

  When the binder resin is a polyester resin, the number average molecular weight (Mn) of the polyester resin is preferably 1000 or more and 2000 or less in order to achieve both the strength of the toner core and the fixing property of the toner. The molecular weight distribution of the polyester resin (the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn)) is preferably 9 or more and 21 or less. Gel permeation chromatography can be used for the measurement of Mn and Mw of the polyester resin.

(Coloring agent)
The toner core may contain a colorant. As the colorant, for example, a known pigment or dye can be used according to the color of the toner. The amount of the colorant to be used is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the binder resin.

  The toner core may contain a black colorant. An example of a black colorant is carbon black. The black colorant may be a colorant that is toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

  The toner core may contain a color colorant such as a yellow colorant, a magenta colorant, or a cyan colorant.

  Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, or arylamide compounds. Suitable examples of yellow colorants include C.I. I. Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155 168, 174, 175, 176, 180, 181, 191, or 194), naphthol yellow S, Hansa yellow G, or C.I. I. Bat yellow is mentioned.

  Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, or perylene compounds. Suitable examples of magenta colorants include C.I. I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 169, 177 184, 185, 202, 206, 220, 221 or 254).

  Examples of cyan colorants include copper phthalocyanine compounds, anthraquinone compounds, or basic dye lake compounds. Suitable examples of cyan colorants include C.I. I. Pigment blue (1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, or 66), phthalocyanine blue, C.I. I. Bat Blue, or C.I. I. Acid blue.

(Release agent)
The toner core may contain a release agent. The release agent is used, for example, for the purpose of improving the fixing property or offset resistance of the toner. In order to increase the anionicity of the toner core, it is preferable to produce the toner core using an anionic wax. In order to improve the fixing property or offset resistance of the toner, the amount of the release agent used is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferably, it is 20 parts by mass or less.

  Suitable examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, or aliphatic hydrocarbon wax such as Fischer-Tropsch wax; oxidized polyethylene wax or Oxides of aliphatic hydrocarbon waxes such as block copolymers of oxidized polyethylene wax; vegetable waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, or rice wax; beeswax, lanolin, or whale wax Animal waxes such as: mineral waxes such as ozokerite, ceresin, or petrolatum; waxes based on fatty acid esters such as montanic acid ester waxes or castor waxes; Nabawakkusu like, part or all of fatty acid esters are de-oxidized waxes.

  In order to improve the compatibility between the binder resin and the release agent, a compatibilizing agent may be added to the toner core.

(Charge control agent)
The toner core may contain a charge control agent. The charge control agent is used, for example, for the purpose of improving the charging stability or charge rising property of the toner. The toner charge rising property is an index of whether or not the toner can be charged to a predetermined charge level in a short time. Further, the anionic property of the toner core can be enhanced by including a negatively chargeable charge control agent in the toner core.

(Magnetic powder)
The toner core may contain magnetic powder. Examples of magnetic powders include iron (more specifically, ferrite or magnetite), ferromagnetic metal (more specifically, cobalt or nickel), a compound containing iron and / or ferromagnetic metal (more specifically, In particular, an alloy or the like), a ferromagnetic alloy that has been subjected to a ferromagnetization treatment (more specifically, a heat treatment or the like), or chromium dioxide.

  In order to suppress elution of metal ions (for example, iron ions) from the magnetic powder, it is preferable to surface-treat the magnetic powder. When a shell layer is formed on the surface of the toner core under acidic conditions, if a metal ion adheres to the surface of the toner core, the toner core and another toner core are easily fixed. By suppressing the elution of metal ions from the magnetic powder, it is possible to suppress adhesion between the toner core and another toner core.

[Shell layer]
As already described, the shell layer includes a plurality of first shell particles and a plurality of second shell particles. Hereinafter, the first shell particles and the second shell particles will be described.

<First shell particles>
The first shell particles include a resin. Specific examples of the resin include acrylic resin, styrene-acrylic resin, silicone-acrylic acid graft copolymer, urethane resin, polyester resin, vinyl resin, epoxy resin, or ethylene-vinyl alcohol copolymer. Can be mentioned. The resin contained in the first shell particles is preferably an acrylic acid resin, a styrene-acrylic acid resin, or a silicone-acrylic acid graft copolymer, and more preferably a styrene-acrylic resin. Hereinafter, the styrene-acrylic acid resin will be described.

  The styrene-acrylic acid resin is a copolymer of a styrene monomer and an acrylic acid monomer. In order to synthesize a styrene-acrylic acid resin, for example, a styrene monomer and an acrylic acid monomer as shown below can be suitably used. By using an acrylic acid monomer, a carboxyl group can be introduced into the styrene-acrylic acid resin. Further, by using a monomer having a hydroxyl group (more specifically, p-hydroxystyrene, m-hydroxystyrene, (meth) acrylic acid hydroxyalkyl ester, or the like), the hydroxyl group can be introduced into the styrene-acrylic acid resin. . The acid value of the styrene-acrylic acid resin obtained can be adjusted by adjusting the amount of the acrylic acid monomer used. Moreover, the hydroxyl value of the styrene-acrylic acid-type resin obtained can be adjusted by adjusting the usage-amount of the monomer which has a hydroxyl group.

  Suitable examples of the styrenic monomer include styrene, α-methylstyrene, p-hydroxystyrene, m-hydroxystyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, Or p-ethylstyrene is mentioned.

  Preferable examples of the acrylic acid monomer include (meth) acrylic acid, (meth) acrylic acid alkyl ester, or (meth) acrylic acid hydroxyalkyl ester. Suitable examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and (meth) acrylic. Examples include n-butyl acid, iso-butyl (meth) acrylate, or 2-ethylhexyl (meth) acrylate. Suitable examples of the (meth) acrylic acid hydroxyalkyl ester include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, or (meth) acrylic. The acid 4-hydroxybutyl is mentioned.

  The first shell particles preferably have a cationic property when the toner core has an anionic property.

  When the number average particle diameter of the first shell particles is 30 nm or more and 90 nm or less, in order to improve the charging stability of the toner, the Tg (glass transition point) of the first shell particles is 60 ° C. or more and 120 ° C. or less. And it is preferable that Tm (softening point) of 1st shell particle | grains is 120 to 210 degreeC. Each measuring method of Tg and Tm is the same method as the Example mentioned later, or its alternative method.

  The content of the first shell particles is preferably 1 part by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the toner core. When the content of the first shell particles is in the above numerical range, the formula (1) is easily satisfied.

<Second shell particles>
The second shell particles include a resin. Specific examples of the resin include acrylic acid resin, styrene-acrylic acid resin, silicone-acrylic acid graft copolymer, urethane resin, polyester resin, vinyl resin, epoxy resin, ethylene-vinyl alcohol copolymer, or Examples of these resins include resins having a crosslinked structure introduced therein. The resin contained in the second shell particles is preferably a cross-linked acrylic acid-based resin, a cross-linked styrene-acrylic acid-based resin, or a cross-linked silicone-acrylic acid-based graft copolymer. An acrylic resin is more preferable. The styrene-acrylic acid resin is synonymous with the styrene-acrylic acid resin of the first shell particles.

  Examples of the crosslinking agent for introducing a crosslinked structure into the resin include a crosslinking monomer. Examples of the crosslinkable monomer include divinylbenzene crosslinkable monomers, diallyl phthalate crosslinkable monomers, and dimethacrylate crosslinkable monomers. Examples of the divinylbenzene-based crosslinking monomer include o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene. Examples of the diallyl phthalate-based crosslinking monomer include diallyl isophthalate and diallyl orthophthalate. Examples of the dimethacrylic acid ester-based crosslinking monomer include ethylene glycol dimethacrylate or triethylene glycol dimethacrylate.

  The content of the second shell particles is preferably 0.5 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the toner core. When the content of the second shell particles is in the above numerical range, the formula (2) is easily satisfied.

[External additive]
The toner particles may further have an external additive. Examples of the external additive include particles of metal oxide (more specifically, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, barium titanate, etc.) or silica particles. For example, the surface of the external additive may be modified with a coupling agent (more specifically, a hydrophobic treatment or a positive charging treatment).

  The number average particle diameter of the external additive is preferably 0.01 μm or more and 1.0 μm or less. The amount of the external additive used is preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner base particles.

  A two-component developer can be prepared by mixing the toner of this embodiment with a desired carrier. When preparing a two-component developer, it is preferable to use a magnetic carrier.

  An example of a suitable carrier is a carrier having a carrier core coated with a resin. Specific examples of carrier cores include iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, or cobalt particles; alloys of these materials with metals such as manganese, zinc, or aluminum Particles of iron-nickel alloy or iron-cobalt alloy; ceramics (more specifically, titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, titanium Particles of barium oxide, lithium titanate, lead titanate, lead zirconate, lithium niobate, etc .; high dielectric constant materials (more specifically, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, or Rochelle salt) Etc.). A resin carrier may be prepared by dispersing the particles in a resin.

  Examples of the resin that coats the carrier core include acrylic acid polymers, styrene polymers, styrene-acrylic acid copolymers, olefin polymers (more specifically, polyethylene, chlorinated polyethylene, or polypropylene). Etc.), polyvinyl chloride, polyvinyl acetate, polycarbonate resin, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, urethane resin, epoxy resin, silicone resin, fluororesin (more specifically, polytetrafluoroethylene) , Polychlorotrifluoroethylene, or polyvinylidene fluoride), phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin, or amino resin. Two or more of these resins may be combined.

  The number average particle diameter of the carrier measured by an electron microscope is preferably 20 μm or more and 120 μm or less, and more preferably 25 μm or more and 80 μm or less.

  When preparing a two-component developer using a toner and a carrier, the toner content is preferably 3% by mass or more and 20% by mass or less with respect to the mass of the two-component developer. It is preferable that it is 15 mass% or less.

[Toner Production Method]
Hereinafter, a method for producing the toner according to the exemplary embodiment will be described. This toner manufacturing method includes, for example, producing a toner core and forming a shell layer, and may include drying, washing, and external addition as necessary. In forming the shell layer, the shell layer is formed on the surface of the toner core.

(Making toner core)
As a method for producing the toner core, for example, a pulverization method or an aggregation method is preferable.

  In the pulverization method, a binder resin and an internal additive (for example, a colorant, a release agent, a charge control agent, or magnetic powder) are mixed. Subsequently, the obtained mixture is melted and kneaded. Subsequently, the obtained kneaded material is pulverized. Subsequently, the obtained pulverized product is classified. As a result, a toner core having a desired particle size can be obtained. According to the pulverization method, the toner core can be prepared relatively easily. The toner core is preferably produced by a pulverization method.

  Aggregation methods include, for example, agglomeration and coalescence. In the aggregation, a plurality of types of particles formed for each component constituting the toner core are aggregated in an aqueous medium to form aggregated particles including a plurality of types of toner core components. In uniting, the components contained in the aggregated particles are united in an aqueous medium to obtain a toner core. According to the aggregation method, it is easy to obtain a toner core having a uniform shape and a uniform particle diameter.

(Forming a shell layer)
In forming the shell layer, the shell layer is formed on the surface of the toner core. Forming the shell layer includes attaching the first shell particles to the surface of the toner core and the second shell particles on the surface of the toner core to which the first shell particles are attached (hereinafter sometimes referred to as a coated toner core). Adhering.

<Adhering the first shell particles to the surface of the toner core>
First shell particles are adhered to the surface of the toner core so as to satisfy the formula (1). Examples of the method for attaching the first shell particles include a fluidized bed method, a spray drying method, a dry method (more specifically, a mechanochemical method, etc.), a granulating and pulverizing method, or an aggregating method.

  In an example of the fluidized bed method, the liquid in which the first shell particles are dispersed is sprayed on the toner core in a fluidized bed state. Thereafter, the first shell particles can be fixed to the surface of the toner core by drying the toner core. As an apparatus used for the fluidized bed method, for example, a particle coating apparatus (“GPCG-5 (SPC)” manufactured by POWREC Co., Ltd.) may be mentioned.

  In an example of the spray drying method, a liquid in which the first shell particles are dispersed is sprayed on the surface of the toner core. Thereafter, the first shell particles can be fixed to the surface of the toner core by drying the toner core. As an apparatus used for the spray drying method, for example, a particle surface modifying apparatus (“Coat Mizer (registered trademark)” manufactured by Freund Sangyo Co., Ltd.) may be mentioned.

  In an example of the dry method, the toner core and the first shell particles are dry mixed. By mixing the toner core and the first shell particles, the first shell particles can be fixed to the surface of the toner core. Among the dry methods, a mechanochemical method in which energy is mechanically and thermally applied to bond the toner core and the first shell particles mechanochemically is particularly preferable. The mechanochemical method of the first step may be the same method as the second step mechanochemical method described later, or may be a different method.

  In an example of the granulation and pulverization method, the liquid in which the first shell particles are dispersed is added to the toner core that is flowing by stirring while stirring the toner core. Thereby, a plurality of toner cores aggregate through the dispersion liquid of the first shell particles, and aggregated particles of the toner core are formed. As a result, a capillary mixture (toner core and first shell particles) is obtained. Subsequently, the obtained mixture in a capillary state is heated while being stirred, whereby the mixture can be pulverized and the first shell particles can be fixed to the surface of the toner core.

  In an example of the aggregation method, the first shell particles and the toner core are dispersed in the liquid, and the first shell particles are adhered to the surface of the toner core. Thereafter, the first shell particles can be fixed to the surface of the toner core by heating the liquid while stirring. From the viewpoint of easily satisfying the formula (1), it is preferable to adhere the first shell particles to the surface of the toner core by an aggregation method.

  Hereinafter, an example of the aggregation method will be described in detail. First, the toner core obtained by producing the toner core is dispersed in an aqueous medium to prepare a toner core dispersion. In order to improve the dispersibility of the toner core, for example, a surfactant may be added, or the pH of the aqueous medium may be adjusted. Examples of the surfactant include a cationic surfactant, an anionic surfactant, and a nonionic surfactant. It is preferable to use a surfactant having the same polarity as that of the toner core. For example, when an anionic toner core is dispersed, an anionic surfactant is preferably used. The aqueous medium is a medium containing water as a main component (more specifically, pure water or a mixed liquid of water and a polar solvent). The aqueous medium may function as a solvent. A solute may be dissolved in the aqueous medium. The aqueous medium may function as a dispersion medium. The dispersoid may be dispersed in the aqueous medium. As a polar medium in the aqueous medium, for example, alcohol (more specifically, methanol or ethanol) can be used. As the aqueous medium, water is preferable from the viewpoint of suppressing dissolution of the binder resin or elution of the release agent. Examples of a method for satisfactorily dispersing the toner core in the aqueous medium include a method in which the toner core is mechanically dispersed in the aqueous medium using an apparatus capable of vigorously stirring the dispersion.

  Subsequently, the first shell particles are added to the toner core dispersion, and while stirring, the temperature of the toner core dispersion is raised to a predetermined temperature and maintained at that temperature for a predetermined time. As a result, the first shell particles adhere to the surface of the toner core. As a result, a toner core dispersion coated with the first shell particles is obtained.

  The pH of the toner core dispersion to which the first shell particles are added is preferably adjusted to about 4 using an acidic substance.

  In order to make the first shell particles adhere favorably to the surface of the toner core, the temperature at which the first shell particles adhere to the surface of the toner core is preferably 40 ° C. or higher and 95 ° C. or lower, preferably 50 ° C. or higher. More preferably, it is 80 ° C. or lower.

  In order to favorably adhere the first shell particles to the surface of the toner core, a hetero-aggregation effect can be used. For example, the charging polarity of the toner core and the charging polarity of the first shell particles are preferably reversed. Examples of the reverse polarity include a combination of an anionic toner core and a cationic first shell particle. As a result, electrostatic attraction functions between the toner core and the first shell particles, and the first shell particles easily adhere to the surface of the toner core.

  In order to favorably adhere the first shell particles to the surface of the toner core, an electrolyte may be added to the mixed liquid of the toner core dispersion and the first shell particles when the first shell particles are adhered to the surface of the toner core. . Examples of the electrolyte include inorganic salts (more specifically, magnesium chloride, sodium chloride, magnesium sulfate, aluminum chloride, and the like).

(Washing)
In the toner manufacturing method, after the first shell particles are attached to the surface of the toner core, the coated toner core is washed with a cleaning liquid as needed, and the coated toner core is recovered from the dispersion of the coated toner core. After the first shell particles are attached to the surface of the toner core as described above, the dispersion containing the coated toner core is cooled to room temperature (for example, 25 ° C.). Thereafter, the coated toner core is washed with a washing liquid. As the cleaning liquid, for example, the above-described aqueous medium can be used.

(Drying)
In the toner production method, after washing, the coated toner core is dried as necessary, and the coated toner core is recovered from the dispersion of the coated toner core. By drying, the coated toner core is dried. A suitable method for drying the coated toner core includes a method using a dryer (for example, a spray dryer, a fluidized bed dryer, a vacuum freeze dryer, or a vacuum dryer). Among these methods, a method using a spray dryer is preferable in order to suppress aggregation of the coated toner core during drying.

<Attaching the second shell particles to the surface of the toner core to which the first shell particles are attached>
By attaching the second shell particles to the surface of the coated toner core, the coated toner core and the second shell particles are mixed by a dry method so as to satisfy the formula (2). By attaching the second shell particles to the surface of the coated toner core, for example, the second shell particles are fixed to the coated toner core using a mechanochemical method. The mechanochemical method is not limited to the structure and principle of the apparatus, and an apparatus capable of simultaneously applying stress such as shearing, compression, or collision can be used. Examples of the apparatus using the mechanochemical method include a ball-type kneader (more specifically, a rotary ball mill), a wheel-type kneader (more specifically, an edge runner), a surface reformer. (“Hybridization system NHS-1” manufactured by Nara Machinery Co., Ltd.), dry particle compounding device (Hosokawa Micron Corporation “Nobilta (registered trademark) NOB-130”, “circulating mechanofusion (registered trademark) system AMS”) , FM mixer (manufactured by Nippon Coke Industries Co., Ltd.).

(External attachment)
In the external addition, the external additive is attached to the surface of the toner base particles. As a suitable method for attaching the external additive, a toner (for example, FM mixer or Nauter mixer (registered trademark)) is used, under the condition that the external additive is not buried in the surface of the toner base particles. A method of mixing the base particles and the external additive can be mentioned.

  The toner manufacturing method can be arbitrarily changed according to the required configuration or characteristics of the toner. For example, in the first step, the toner core may be added to the aqueous medium after the first shell particles are dispersed in the aqueous medium. Alternatively, the first core particles may be dispersed in the aqueous medium after the toner core is dispersed in the aqueous medium. Further, various things may be omitted depending on the use of the toner. When the external additive is not attached to the surface of the toner base particles (the external addition is omitted), the toner base particles correspond to the toner particles. In order to produce the toner efficiently, it is preferable to form a large number of toner particles simultaneously.

  Examples will be described below. Tables 1 and 2 show the toners of Examples 1 to 30 and the toners of Comparative Examples 1 to 17 (each electrostatic latent image developing toner). The contents of the first shell particles and the second shell particles are each a mass with respect to 100 parts by mass of the toner core.

(Preparation of first shell particle suspension B-1)
A four-necked flask was used as a reaction vessel. The four-necked flask is a 1 L reaction vessel equipped with a thermometer, a stirring blade, a reflux cooling device, and a monomer dropping port. The reaction vessel is set in a water bath, 360 parts by mass of ion-exchanged water for emulsification, and reaction emulsifier (“ADEKA rear sorb (registered trademark) SR-1025” manufactured by ADEKA Corporation, component: ether sulfate ammonium salt, concentration) : 25% by mass, solvent: water) was added in an amount of 2.0 parts by mass. Subsequently, the temperature in the reaction vessel was raised to 80 ° C. using a water bath. The ion-exchanged water for emulsification is ion-exchanged water deoxygenated beforehand by nitrogen bubbling.

  Subsequently, 30 parts by mass of styrene, 50 parts by mass of n-butyl acrylate, 20 parts by mass of 2-hydroxyethyl methacrylate, and a reactive emulsifier (“ADEKA rear sorb (registered trademark) SR-1025” manufactured by ADEKA Corporation, components: 3.2 parts by mass of ether sulfate type ammonium salt, concentration: 25% by mass, solvent: water) and 40 parts by mass of ion-exchanged water for emulsification were produced by a high-speed shear emulsification device (“CLEAMIX (registered by M Technique Co., Ltd.)). (Trademark) CLM-2.2S ") and emulsified under conditions of a rotation speed of 10,000 rpm and a treatment time of 5 minutes. As a result, a monomer suspension was obtained.

  A reaction vessel was charged with 0.2 parts by mass of ammonium persulfate. Subsequently, 28.6 parts by mass (20% by mass of the amount used) of the monomer suspension was charged into the reaction vessel, and emulsion polymerization was performed for 30 minutes. Thereafter, 114.5 parts by mass (remaining 80% by mass) of the monomer suspension was dropped into the reaction vessel over 3 hours. After completion of the dropwise addition, the emulsion polymerization was continued for another hour. Thereafter, 5.9 parts by mass of ion-exchanged water for dilution was added to the reaction vessel, and the reaction vessel was cooled to a temperature of 40 ° C. or lower to obtain a suspension. Subsequently, ion-exchanged water was added to the reaction vessel, and the solid content concentration and pH of the vessel contents were adjusted to obtain a first shell particle suspension B-1. With respect to the obtained suspension B-1, the solid content concentration was 10% by mass and the pH at 25 ° C. was 2.6. Moreover, regarding the 1st shell particle | grains in suspension B-1, the number average particle diameter was 45 nm, SP value was 10.0, Tg was 77 degreeC, and Tm was 164 degreeC. The first shell particle suspension B-1 had good storage stability.

(First shell particle suspensions B-2 to B-7)
The second input amount of the reactive emulsifier is 2.0 parts by mass and the first input amount of water is 360 parts by mass, respectively. Except having changed into input amount, it carried out similarly to preparation of 1st shell particle suspension B-1, and produced 1st shell particle suspension B-2-B-7. The SP values of the first shell particles of the suspensions B-2 to B-7 were all 10.0. Table 3 shows Tg and Tm of the first shell particles of the suspensions B-2 to B-7.

(Preparation of second shell particle suspension C-1)
A four-necked flask was used as a reaction vessel. The four-necked flask is a 1 L reaction vessel equipped with a thermometer, a stirring blade, a reflux cooling device, and a monomer dropping port. The reaction vessel is set in a water bath, and 200 parts by mass of ion-exchanged water for emulsification and an anionic surfactant (“Emar (registered trademark) 0 (sodium lauryl sulfate)” manufactured by Kao Corporation) 1.5 mass in the reaction vessel. Department was put in. Subsequently, the temperature in the reaction vessel was raised to 80 ° C. using a water bath.

  Subsequently, 45 parts by weight of methyl methacrylate, 50 parts by weight of styrene, 5 parts by weight of divinylbenzene, 3 parts by weight of an anionic surfactant (“Emar 0 (sodium lauryl sulfate)” manufactured by Kao Corporation), and ions for emulsification 40 parts by mass of exchange water was emulsified using a high-speed shearing emulsifier (“CLEARMIX (registered trademark) CLM-2.2S” manufactured by M Technique Co., Ltd.) under the conditions of a rotation speed of 10,000 rpm and a processing time of 5 minutes. . As a result, a monomer suspension was obtained.

  Subsequently, 1.0 part by mass of ammonium persulfate was charged into the reaction vessel. Subsequently, 100 parts by mass of the monomer suspension was dropped into the reaction vessel over 3 hours to carry out emulsion polymerization. After completion of the dropwise addition, the emulsion polymerization was further continued for 1 hour to obtain a second shell particle suspension C-1. Regarding the second shell particles in the suspension C-1, the number average particle diameter was 80 nm, and the SP value was 9.5.

(Second shell particle suspension C-2 to C-8)
The same procedure as in the preparation of the second shell particle suspension C-1, except that 1.5 parts by mass of the first input amount of Emar 0 was changed to the first input amount of Emar 0 shown in Table 4. Thus, second shell particle suspensions C-2 to C-8 were prepared. The SP values of the second shell particles in the second shell particle suspensions C-2 to C-7 were all 9.5.

(Second Shell Particle Suspension C-9 to C-10)
The first input amount of cetyltrimethylammonium chloride described in Table 4 and the cetyl amount of 1.5 parts by mass of the first input amount of Emar 0 and 3.0 parts by mass of the second input amount of Emar 0, respectively. Second shell particle suspensions C-9 and C-10 were prepared in the same manner as the preparation of the second shell particle suspension C-1, except that the amount of trimethylammonium chloride was changed to the second charge amount. . The SP values of the second shell particles in the second shell particle suspensions C-9 and C-10 were both 9.5.

Example 1
(Production of toner core)
Binder resin (polyester resin, Tg = 42 ° C., Tm = 85 ° C., acid value 18.5 mgKOH / g) 100 parts by mass and colorant (CI pigment blue 15: 3, component: copper phthalocyanine pigment) 4 5 parts by mass of ester wax (“Nissan Electol (registered trademark) WEP-3” manufactured by NOF Corporation) and quaternary ammonium salt (“BONTRON (registered trademark) P-51 manufactured by Orient Chemical Co., Ltd.) ]) 1 part by mass was mixed using an FM mixer (Nippon Coke Kogyo Co., Ltd.). The obtained mixture was melted and kneaded using a twin screw extruder ("PCM-30" manufactured by Ikegai Co., Ltd.). After cooling the obtained kneaded material, the kneaded material was coarsely pulverized by a pulverizer (“Rohtoplex (registered trademark) 16/8 type” manufactured by Hosokawa Micron Corporation). Subsequently, the obtained coarsely pulverized product was finely pulverized with a pulverizer (“Turbo Mill” manufactured by Freund Turbo). Subsequently, the obtained finely pulverized product was classified with a classifier (“Elbow Jet EJ-LABO type” manufactured by Nippon Steel Mining Co., Ltd.) to obtain toner core A. With respect to the obtained toner core A, the volume median diameter (D ₅₀ ) was 6.8 μm, the number average circularity was 0.95, and the SP value was 10.5.

(Shell layer formation step)
[First step]
A three-necked flask was used as a reaction vessel. This three-necked flask is a 1 L capacity reaction vessel equipped with a thermometer and stirring blades. The reaction vessel was set in a water bath. Then, 261 parts by mass of ion-exchanged water and 29 parts by mass of an anionic surfactant (“Emar E27C” manufactured by Kao Corporation) were added to the reaction vessel to prepare an aqueous anionic surfactant solution having a concentration of 1% by mass. Subsequently, 100 parts by mass of the toner core was charged into the reaction container. The temperature in the reaction vessel was maintained at 35 ° C. using a water bath. Using a high-speed shearing emulsifier (“CLEARMIX (registered trademark) CLM-2.2S” manufactured by M Technique Co., Ltd.), the contents of the reaction vessel are stirred under conditions of a temperature of 35 ° C. and a rotation speed of 10,000 rpm to disperse the toner core. A liquid was prepared.

  10 parts by mass of the first shell particle suspension B-3 (solid content concentration: 10% by mass) was charged into the reaction vessel. Note that the mass of the solid content of the first shell particle suspension B-3 added corresponds to 1% of the mass of the toner core. In order to adhere the first shell particles to the surface of the toner core and stabilize the dispersion of the toner core, the pH of the content of the reaction vessel was adjusted to 3.5 while dropping hydrochloric acid into the reaction vessel. Then, the contents of the reaction vessel were stirred for 30 minutes at a temperature of 35 ° C. Thereafter, the temperature in the reaction vessel was raised to 65 ° C. while stirring was continued, and the temperature was maintained at 65 ° C. for 30 minutes. Thereafter, the temperature in the reaction vessel was rapidly cooled to 25 ° C. to obtain a suspension.

The obtained suspension was subjected to solid-liquid separation using a Buchner funnel to obtain a solid content. The obtained solid content was repeatedly washed with ion-exchanged water until the filtrate had a conductivity of 3 μS / m or less. Thereafter, the solid content was dried until the water content became 0.5% by mass or less to obtain a coated toner core. Regarding the coated toner core, the volume median diameter (D ₅₀ ) was 6.8 μm, the number average circularity was 0.970, and C _F was 34.1%. The number average circularity was measured using a flow type particle image analyzer (“FPIA (registered trademark) -3000” manufactured by Sysmex Corporation).

[Second step]
101 parts by weight of the coated toner core (toner core coated with the first shell particles) and 1 part by weight of the second shell particles obtained from the second shell particle suspension C-1 were combined into a dry particle composite apparatus (Hosokawa Micron Corporation) Using “Nobilta (registered trademark) NOB-130” manufactured by the company, the composite was processed under the conditions of a rotational speed of 5000 rpm and a processing time of 1 minute. As a result, toner mother particles coated with a shell layer were obtained. With respect to the obtained toner base particles, the circularity was 0.972, the volume median diameter (D ₅₀ ) was 6.8 μm, and C _S was 17.0%.

(External)
100 parts by mass of toner base particles and 1.5 parts by mass of dry silica particles (“AEROSIL (registered trademark) REA90” manufactured by Nippon Aerosil Co., Ltd .: silica particles subjected to a positively chargeable hydrophobic treatment) were mixed with FM mixer (Nippon Coke). For 3 minutes to make silica particles adhere to the toner base particles. Thereafter, the obtained toner was sieved with a 300 mesh (aperture 48 μm) sieve to obtain the toner of Example 1.

Examples 2-30 and Comparative Examples 1-17
Of the first shell particle suspension (B-3), the ratio of the first shell particle suspension of 1.0% by mass, the second shell particle suspension (C-1), and the second shell particle suspension. The ratio of the first shell particle suspension, the ratio of the first shell particle suspension, the type of the second shell particle suspension (C-1) described in Tables 1 and 2, respectively, with a proportion of 1.0% by mass, The toner of Examples 2 to 30 and the toner of Comparative Examples 1 to 17 were obtained in the same manner as in the preparation of the toner of Example 1, except that the ratio was changed to the ratio of the second shell particle suspension.

[Evaluation method]
The evaluation method of each sample (the toner of Examples 1 to 30 and the toner of Comparative Examples 1 to 17) is as follows.

(Coverage by first shell particles)
For the coated toner cores of the samples (the toners of Examples 1 to 30 and the toners of Comparative Examples 1 to 17), the coverage with the first shell particles was measured. The coverage with the first shell particles was determined as follows. The coated toner core of the sample (toner) was allowed to stand for 5 minutes on 2 mL of 0.5% by weight ruthenium tetroxide solution to expose the coated toner core to a ruthenium vapor atmosphere. As a result, a coated toner core dyed with ruthenium was obtained. Subsequently, the dyed coated toner core is observed at a magnification of 100,000 using a field emission scanning electron microscope (FE-SEM) (“JSM-7600F” manufactured by JEOL Ltd.), and the reflected electrons of the coated toner core are observed. I got a statue. Each of the pixels constituting the reflected electron image of the obtained coated toner core had a luminance value of 0 or more and 255 or less. Using image analysis software (“WinROOF” manufactured by Mitani Shoji Co., Ltd.), a luminance value distribution (luminance distribution) of the coated toner core was obtained from the reflected electron image of the coated toner core. This luminance distribution was a luminance distribution in which the horizontal axis represents luminance and the vertical axis represents frequency.

A distribution represented by a Gaussian function (hereinafter sometimes referred to as a Gaussian luminance distribution) was fitted to the luminance distribution of the toner core and the luminance distribution of the first shell particles in the luminance distribution of the coated toner core. Here, the luminance distribution of the toner core is a distribution of luminance values of only the toner core. The luminance distribution of the first shell particles is a distribution of luminance values of only the first shell particles. By fitting, the luminance distribution of the coated toner core was waveform-separated into a Gaussian luminance distribution of the toner core and a Gaussian luminance distribution of the first shell particles. The area of the Gaussian luminance distribution of the toner core after fitting (waveform separation) and the area of the Gaussian luminance distribution of the first shell particles were determined. The sum of the area of the Gaussian luminance distribution of the toner core and the area of the Gaussian luminance distribution of the first shell particles was determined. From the area of the Gaussian luminance distribution of the obtained first shell particles and the sum of the area of the Gaussian luminance distribution of the toner core and the area of the Gaussian luminance distribution of the first shell particles, the following formula (6) is used to calculate C _F Asked.
C _F (%) = [area of Gaussian luminance distribution of first shell particles / sum of area of Gaussian luminance distribution of toner core and area of Gaussian luminance distribution of first shell particles] × 100 (6)

(Coverage by second shell particles)
For each sample (the toner of Examples 1 to 30 and the toner of Comparative Examples 1 to 17), the coverage with the second shell particles was measured. The coverage with the second shell particles was determined as follows. A reflected electron image of the toner particles was obtained in the same manner as the method for measuring the coverage of the first shell particles, except that the object to be measured was changed from the coated toner core to the toner particles. The brightness distribution of the toner particles was obtained from the reflected electron image of the toner particles using image analysis software (“WinROOF” manufactured by Mitani Corporation).

A distribution represented by a Gaussian function was fitted to the luminance distribution of the toner core, the luminance distribution of the first shell particles, and the luminance distribution of the second shell particles in the luminance distribution of the toner particles. Here, the luminance distribution of the second shell particles is a distribution of luminance values of only the second shell particles. By fitting, the luminance distribution of the toner particles was separated into a waveform into a Gaussian luminance distribution of the toner core, a Gaussian luminance distribution of the first shell particles, and a Gaussian luminance distribution of the second shell particles. The area of the Gaussian luminance distribution of the toner core after fitting (waveform separation), the area of the Gaussian luminance distribution of the first shell particles, and the area of the Gaussian luminance distribution of the second shell particles were determined. The sum of the area of the Gaussian luminance distribution of the toner core, the area of the Gaussian luminance distribution of the first shell particles, and the area of the Gaussian luminance distribution of the second shell particles was determined. From the area of the Gaussian luminance distribution of the obtained second shell particles, and the sum of the area of the Gaussian luminance distribution of the toner core, the area of the Gaussian luminance distribution of the first shell particles, and the area of the Gaussian luminance distribution of the second shell particles, Using the equation (7), C _S was obtained.
C _S (%) = [area of Gaussian luminance distribution of second shell particle / sum of area of Gaussian luminance distribution of toner core, area of Gaussian luminance distribution of first shell particle, and area of Gaussian luminance distribution of second shell particle] ] × 100 (7)

(Glass transition point (Tg))
The glass transition point (Tg) of the resin was measured as follows. As a measuring device, a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.) was used. 10 mg of resin was placed in an aluminum pan. An empty aluminum pan was used as a reference. An endothermic curve was obtained under the conditions of a temperature range of 25 ° C. to 200 ° C., a heating rate of 10 ° C./min, and a normal temperature and normal humidity environment (temperature 23 ° C., relative humidity 50% RH). In the obtained endothermic curve, the temperature at the intersection of the base line of the chart and the tangent line of the endothermic curve near the glass transition point was defined as the glass transition point.

(Softening point (Tm))
The softening point (Tm) of the resin was measured as follows. First, the resin was allowed to stand for 12 hours or more in an environment of normal temperature and normal humidity (temperature: 23 ° C. ± 1 ° C., relative humidity: 50% RH ± 5% RH) to condition the resin. Subsequently, 1.1 parts by mass of the conditioned resin was pressure-molded at a pressure of 10 MPa using a pressure molding machine to produce a cylindrical molded sample having a diameter of 1 cm. Subsequently, the molded sample was subjected to a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation) in an environment of normal temperature and normal humidity (temperature: 23 ° C. ± 5 ° C., relative humidity: 50% RH ± 10% RH). ) Was used to melt and flow out the resin under predetermined conditions. Here, the predetermined conditions were a used nozzle of 1 mmφ × 10 mm, a load of 294 N (30 Kgf), a preheating time of 5 minutes, and a heating rate of 3 ° C./minute. In this way, the S-curve of the resin (horizontal axis: temperature, vertical axis: stroke) was measured. The Tm of the resin was read from the obtained S-shaped curve. Specifically, in the obtained S-shaped curve, when the maximum stroke value is S ₁ and the baseline stroke value on the low temperature side is S ₂ , the stroke value in the S-shaped curve is “(S ₁ + S _The temperature (° C.) at which “ ₂ ) / 2” was obtained was the Tm of the resin.

(Print life test)
A resin-coated ferrite carrier produced by the following method and a sample (toner) were mixed for 30 minutes using a ball mill to obtain a developer for evaluation having a toner concentration of 10% by mass.

(Creation of carrier)
39.7Mol% in terms of MnO, 9.9 mol% in terms of MgO, 49.6Mol% in terms of Fe ₂ O _3, and so that 0.8 mol% in terms of SrO, each raw material (specifically, MnO, MgO, Fe ₂ O ₃ and SrO) were blended in appropriate amounts, added with water, ground using a wet ball mill for 10 hours, and then mixed. Subsequently, the resulting mixture was dried and then kept at 950 ° C. for 4 hours.

Subsequently, the mixture was ground using a wet ball mill for 24 hours to obtain a slurry. Subsequently, the slurry was granulated and then dried. Subsequently, the dried granulated product was crushed after being held at 1270 ° C. for 6 hours in an atmosphere having an oxygen concentration of 2%. Thereafter, by adjusting the particle size, manganese-based ferrite particles (carrier core) were obtained. Regarding the obtained carrier core, the number average particle diameter was 35 μm, and the saturation magnetization when the applied magnetic field was 3000 (10 ³ / 4π · A / m) was 70 Am ² / kg.

  Subsequently, a polyamideimide resin (a copolymer of trimellitic anhydride and 4,4′-diaminodiphenylmethane) was dissolved in methyl ethyl ketone to prepare a resin solution. Subsequently, tetrafluoroethylene / hexafluoropropylene copolymer (FEP) as a fluororesin and silicon oxide (2 mass% of the total amount of the resin) are dispersed in the resin solution, and 150 mass in terms of solid content. An amount of carrier coating solution was obtained. Regarding the obtained carrier coat liquid, the mass ratio of the polyamideimide resin and FEP was 2/8 (= polyamideimide resin / FEP), and the solid content concentration of the resin solution was 10 mass%.

  Subsequently, 10,000 parts by mass of the manganese-based ferrite particles (carrier core) were coated with the carrier coating solution by using a rolling fluidized bed coating apparatus (“Spyra Coater (registered trademark) SP-25” manufactured by Okada Seiko Co., Ltd.). . Thereafter, the manganese-based ferrite particles coated with the resin were fired at 220 ° C. for 1 hour. Thereafter, the obtained fired product was cooled and crushed to obtain a resin-coated ferrite carrier having a resin coating amount of 3% by mass.

  A color printer (“FS-C5400DN” manufactured by Kyocera Document Solutions Inc.) was used as an evaluation machine. The developer for evaluation prepared as described above was charged into the developing device of the evaluation machine, and the sample (toner) was charged into the toner container of the evaluation machine. Using an evaluation machine, a printing durability test was performed to form 10,000 images at a printing rate of 5%.

(Heat-resistant blocking property)
In the evaluation of the heat-resistant blocking property of the toner, the above-mentioned printing test is performed in a normal temperature and normal humidity environment (temperature 23 ° C., relative humidity 50% RH), and a sample (toner) collected by cleaning during the printing test is used. The degree of aggregation was measured. Specifically, 10 g of the sample collected by cleaning was left in a thermostatic chamber adjusted to 58 ° C. for 8 hours. Subsequently, the sample that was allowed to stand was sieved using a sieve having an opening of 45 μm. After sieving, the mass of the sample remaining on the sieve was measured. From the mass of the sample before sieving and the mass of the sample remaining on the sieving after sieving, the degree of aggregation (% by mass) of the toner was calculated according to the following formula.
Aggregation degree (mass%) = (mass of sample remaining on sieve / mass of sample before sieving) × 100

From the calculated degree of aggregation, the heat blocking resistance of the toner was evaluated according to the following criteria.
○ (Good): The degree of aggregation was less than 50% by mass.
X (Poor): Aggregation degree was 50% by mass or more.

(Low temperature fixability)
In the evaluation of the low-temperature fixability of the sample (toner), after performing the printing durability test in a normal temperature and normal humidity environment (temperature 23 ° C., relative humidity 50% RH), a linear velocity of 200 mm / second ( A solid image having a size of 25 mm × 25 mm and a printing rate of 100% is formed on 90 g / m ² paper (A4 size evaluation paper) under the conditions of a nip passage time of 40 ms and a toner loading of 1.0 mg / cm ^2. did. Subsequently, the paper on which the image was formed was passed through the fixing device. The setting range of the fixing temperature was 80 ° C. or higher and 180 ° C. or lower. Specifically, the fixing temperature of the fixing device was gradually increased from 80 ° C., and the minimum temperature (minimum fixing temperature) at which the toner (solid image) can be fixed on paper was measured.

  Whether or not the toner could be fixed in the measurement of the minimum fixing temperature was confirmed by a rubbing test as shown below. Specifically, the paper was folded in half so that the surface on which the image was formed was inside, and a 1 kg weight covered with a cloth was used to rub the crease 5 times. Subsequently, the paper was spread and the bent portion of the paper (the portion where the solid image was formed) was observed. Then, the length (peeling length) of toner peeling at the bent portion was measured. The lowest temperature among the fixing temperatures at which the peeling length was less than 1 mm was defined as the lowest fixing temperature.

From the lowest fixing temperature obtained, the low-temperature fixability of the toner was evaluated according to the following criteria.
○ (Good): The minimum fixing temperature was less than 120 ° C.
X (Poor): The minimum fixing temperature was 120 ° C. or higher.

(Print life)
In the evaluation of the printing durability of the toner, the printing durability test was performed in a normal temperature and normal humidity environment (temperature 23 ° C., relative humidity 50% RH). Before and after performing the printing durability test, a solid image is formed using the evaluation machine, and the formed image is measured using a reflection densitometer (“SpectroEye (registered trademark) LT” manufactured by Sakata Inx Engineering Co., Ltd.). Image density was measured. The image density at any 10 points in the solid image was measured. The average value of the image density of 10 points was used as the evaluation value of the image density. From the obtained image density ID ₁₁ before the printing test and the image density ID ₁₂ after the printing test, the difference ΔID _{1 in} image density before and after the printing test was calculated based on the following equation.
ΔID ₁ = | ID ₁₁ −ID ₁₂ |

From the image density difference ΔID ₁ obtained, the printing durability of the toner was evaluated according to the following criteria.
○ (Good): The difference in image density was less than 0.3.
X (Poor): The difference in image density was 0.3 or more.

(Environment resistance)
In the evaluation of the environmental resistance of the toner, a low temperature and low humidity environment (L / L environment: temperature 20 ° C., relative humidity 65% RH) and a high temperature high humidity environment (H / H environment: temperature 32 ° C., relative humidity 80% RH) Then, the printing durability test was performed separately. Further, after each printing durability test, a solid image is formed using the above-described evaluation machine, and the formed image is imaged using a reflection densitometer ("SpectroEye (registered trademark) LT" manufactured by Sakata Inx Engineering Co., Ltd.). Concentration was measured. The image density at any 10 points in the solid image was measured. The average value of the image density of 10 points was used as the evaluation value of the image density. Based on the obtained image density ID ₂₁ after the printing test in the L / L environment and the image density ID ₂₂ after the printing test in the H / H environment, the image density due to the environmental change is calculated based on the following equation. The difference ΔID ₂ was calculated.
ΔID ₂ = | ID ₂₁ −ID ₂₂ |

From the obtained image density difference .DELTA.ID _2, was evaluated environmental resistance of the toner according to the following criteria.
A (very good): The difference in image density was less than 0.3.
○ (Good): The difference in image density was 0.3 or more and less than 0.5.
X (Poor): The difference in image density was 0.5 or more.

[Evaluation results]
Tables 5 and 6 show the evaluation results of the heat-resistant blocking property and the low-temperature fixability of the samples (the toners of Examples 1 to 30 and the toners of Comparative Examples 1 to 17). Tables 7 and 8 show the evaluation results of the printing durability and environmental resistance of the samples (the toners of Examples 1 to 30 and the toners of Comparative Examples 1 to 17).

The toner according to Examples 1 to 30 was a toner having the above-described configuration (1). Specifically, in the toners according to Examples 1 to 30, C _F satisfies Formula (1), C _S satisfies Formula (2), and SP _T , SP _F, and SP _{S are} formulas. (3) was satisfied.

  The toners according to Examples 1 to 30 all showed excellent results in evaluation of heat blocking property, low temperature fixability, and image density (printing durability test).

  Therefore, the toners according to Examples 1 to 30 are excellent in low-temperature fixability and heat-resistant storage stability as compared with the toners according to Comparative Examples 1 to 17, respectively, and images having an appropriate image density over a long period of time. Could be formed.

  Furthermore, the toner according to Examples 1 and 3 to 8 and the toner according to Examples 11 to 30 each have a particle diameter of the first shell particles of 30 nm or more and 90 nm or less, and the particle diameter of the second shell particles. It was 70 nm or more and 300 nm or less. The toners according to Examples 1 and 3 to 8 and the toner according to Examples 11 to 30 also showed excellent results in evaluation of image density (environment resistance). The toners according to Examples 1 and 3 to 8 and the toners according to Examples 11 to 30 were further excellent in charging stability.

  The toner for developing an electrostatic latent image according to the present invention can be used for forming an image in, for example, a copying machine or a printer.

10 toner base particles 11 toner core 12 shell layer 12a first shell particles 12b second shell particles

Claims (6)

An electrostatic latent image developing toner comprising a plurality of toner particles having a toner core and a shell layer covering the surface of the toner core,
The shell layer includes a plurality of first shell particles and a plurality of second shell particles,
The first shell particles coat the toner core;
The second shell particles further coat the toner core coated with the first shell particles;
The toner core includes a polyester resin as a binder resin,
The first shell particles include an uncrosslinked styrene-acrylic acid resin,
The second shell particles include a crosslinked styrene-acrylic acid resin,
The coverage (C _F ) by the first shell particles satisfies the following formula (1):
The coverage (C _S ) by the second shell particles satisfies the following formula (2):
The glass transition point of the first shell particles is 60 ° C. or more and 120 ° C. or less,
The softening point of the first shell particles is 120 ° C. or higher and 210 ° C. or lower,
The first shell particles have a cationic property,
The solubility parameter (SP _T ) of the toner core, the solubility parameter (SP _F ) of the first shell particles, and the solubility parameter (SP _S ) of the second shell particles satisfy the following formula (3). Toner for electrostatic latent image development.
25% ≦ C _F ≦ 50% (1)
5% ≦ C _S ≦ 30% (2)
SP _T > SP _F > SP _S (3) The number average particle size of the first shell particles is smaller than the number average particle size of the second shell particles,
2. The electrostatic latent image development according to claim 1, wherein the number average particle diameter of the first shell particles and the second shell particles is 0.005 to 0.04 times the number average particle diameter of the toner core. Toner. The number average particle diameter of the first shell particles is 30 nm or more and 90 nm or less,
The electrostatic latent image developing toner according to claim 1, wherein the number average particle diameter of the second shell particles is 70 nm or more and 300 nm or less. 4. The electrostatic latent image developing according to claim 1, wherein the SP _T , the SP _F, and the SP _S satisfy the following expressions (4) and (5). toner.
| SP _T −SP _F | ≦ 1.0 (4)
| SP _F −SP _S | ≦ 1.0 (5) The toner particles further comprises, an electrostatic latent image developing toner according to any one of claims 1-4 with an external additive. A method for producing a toner for developing an electrostatic latent image, comprising:
The electrostatic latent image developing toner is the electrostatic latent image developing toner according to any one of claims 1 to 5 ,
Forming the shell layer on a surface of the toner core;
Forming the shell layer includes
Attaching the first shell particles to the surface of the toner core so as to satisfy the formula (1);
The toner core to which the first shell particles are adhered and the second shell particles are mixed in a dry manner so that the formula (2) is satisfied, whereby the second core is adhered to the surface of the toner core to which the first shell particles are adhered. A method for producing a toner for developing an electrostatic latent image, comprising: attaching shell particles.

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