JP2018132631A - Toner for electrostatic latent image development and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for electrostatic latent image development that has sufficient chargeability in both a normal-temperature and normal-humidity environment and a high-temperature and high-humidity environment, and is excellent in high-temperature offset resistance.SOLUTION: Toner particles 10 each include a toner core 11, a shell layer 12, and a plurality of wax particles. The shell layer 12 contains resin and covers a portion of a surface area of the toner core 11. The surface of the shell layer 12 has a sea-like area R2, and a plurality of island-like areas R1 that each are surrounded by the sea-like area R2. The sea-like area R2 has stronger hydrophobicity than those of the island-like areas R1. The island-like areas R1 each have stronger chargeability than that of the sea-like area R2. The wax particles include core external additive wax particles 13. The core external additive wax particles 13 are provided on portions exposed from the shell layer 12 of the surface area of the toner core 11. The content of the wax particles in the toner is 1 parts by mass or more and 35 parts by mass or less based on 100 parts by mass of the resin contained in the shell layer 12.SELECTED DRAWING: Figure 1

Description

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

  As toner particles contained in the toner, capsule toner is known (for example, see Patent Document 1). The capsule toner includes a toner core and a shell layer that covers the surface of the toner core. Patent Document 1 describes the following. The toner core may contain a wax that functions as a release agent in the fixing step. The shell layer is composed of a monomer copolymer having a quaternary ammonium group.

JP 2014-48501 A

  A quaternary ammonium group is a cationic functional group. By increasing the density of the cationic functional group in the shell layer, it is considered that the positive chargeability of the toner in a normal temperature and normal humidity environment can be enhanced. However, when the density of the cationic functional group in the shell layer is increased, the hydrophilicity of the surface of the toner particles is increased, and water molecules are easily adsorbed on the surface of the toner particles. When water molecules are adsorbed on the surface of the toner particles, the positive charge amount of the toner particles tends to be attenuated. For this reason, if the density of the cationic functional group in the shell layer is too high, the positive chargeability of the toner in a high temperature and high humidity environment may be insufficient. When an image is formed using a toner having insufficient positive chargeability, the formed image is likely to be fogged.

  Further, when the toner core contains a wax, the wax hardly exists on the surface of the toner particles. Therefore, it is difficult for the wax to function as a release agent in the fixing step. Therefore, a high temperature offset may occur.

  The present invention has been made in view of the above problems, and its purpose is to develop an electrostatic latent image having sufficient chargeability in a normal temperature and normal humidity environment and a high temperature and high humidity environment and having excellent high temperature offset resistance. To provide toner. Another object of the present invention is to provide a method for producing such an electrostatic latent image developing toner.

  The electrostatic latent image developing toner according to the present invention includes a plurality of toner particles. Each of the toner particles includes a toner core, a shell layer, and a plurality of wax particles. The shell layer contains a resin and covers a part of the surface region of the toner core. The surface of the shell layer has a sea region and a plurality of island regions each surrounded by the sea region. The sea region has stronger hydrophobicity than each of the island regions. Each of the island regions has a charging property stronger than that of the sea region. The wax particles include core externally added wax particles. The core externally added wax particles are provided in a portion of the surface area of the toner core exposed from the shell layer. The content of the wax particles in the electrostatic latent image developing toner is 1 part by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the resin.

  The method for producing a toner for developing an electrostatic latent image according to the present invention is a method for producing a toner for developing an electrostatic latent image having the above-described configuration. Specifically, the method for producing a toner for developing an electrostatic latent image according to the present invention includes a step of producing the toner core, a step of preparing a dispersion of the wax particles, a step of preparing a first dispersion, 2 The process of preparing a dispersion liquid and the process of forming the said shell layer are included. The first dispersion is a dispersion of particles containing a marine region resin. The second dispersion is a dispersion of particles containing an island-shaped region resin. The step of forming the shell layer includes a step of mixing the toner core, the wax particle dispersion, the first dispersion, and the second dispersion at a predetermined temperature.

  According to the present invention, it is possible to provide a toner for developing an electrostatic latent image having sufficient chargeability in a normal temperature and normal humidity environment and a high temperature and high humidity environment. In addition, it is possible to provide a toner for developing an electrostatic latent image having excellent high temperature offset resistance.

It is a figure which shows an example of the cross-section of the toner particle contained 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 the toner particle shown in FIG. 1. FIG. 2 is a view showing a part of the surface structure of toner particles shown in FIG. 1. FIG. 4 is an enlarged view showing a part of the surface of toner particles contained in an electrostatic latent image developing toner according to an embodiment of the present invention. FIG. 5 is a diagram showing a part of the surface structure of the toner particles shown in FIG. 4. FIG. 4 is an enlarged view showing a part of the surface of toner particles contained in an electrostatic latent image developing toner according to an embodiment of the present invention.

  Embodiments of the present invention will be described in detail. In addition, the evaluation result (a value indicating the shape or physical properties) of the powder is a value obtained by selecting a considerable number of average particles from the powder and measuring each of the average particles unless otherwise specified. Is the number average. The powder includes, for example, a toner core, toner base particles, an external additive, and toner. The toner base particles mean toner particles in a state where no external additive is attached.

The number average particle diameter of the powder is the number average value of the equivalent circle diameter of primary particles (diameter of a circle having the same area as the projected area of the particles) measured using a microscope unless otherwise specified. . Moreover, the measured value of the volume median diameter (D ₅₀ ) of the powder is not specified, and the “Coulter Counter Multisizer 3” manufactured by Beckman Coulter Co., Ltd. is used. ) Measured based on.

  The glass transition point (Tg) and the melting point (Mp) are values measured using a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.) unless otherwise specified. Moreover, the softening point (Tm) is a value measured using a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation) unless otherwise specified.

  The strength of the charging property corresponds to the ease of frictional charging unless otherwise specified. For example, the toner can be triboelectrically charged by mixing and stirring with a standard carrier (anionic: N-01, cationic: P-01) provided by the Imaging Society of Japan. The surface potential of the toner particles is measured with, for example, KFM (Kelvin probe force microscope) before and after the frictional charging, and the portion having a larger potential change before and after the frictional charging has a higher charging property.

  A compound and its derivatives 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. Acrylic and methacrylic are sometimes collectively referred to as “(meth) acrylic”. Further, acrylonitrile and methacrylonitrile may be collectively referred to as “(meth) acrylonitrile”.

  The electrostatic latent image developing toner according to the present embodiment (hereinafter sometimes simply referred to as “toner”) may constitute a one-component developer, or an electrostatic latent image developing carrier (hereinafter referred to as “toner”). A two-component developer may be configured together with a “carrier”.

  The toner according to the exemplary embodiment can be used for image formation in, for example, an electrophotographic apparatus (image forming apparatus). Examples of a method for forming an image using the toner according to the present embodiment include the following methods. First, the charging device uniformly charges the photosensitive layer of the photosensitive drum. Next, the exposure apparatus forms an electrostatic latent image on the photosensitive layer based on the image data. Subsequently, the developing device develops the electrostatic latent image using toner carried on the magnetic roller. As a result, a toner image is formed on the photosensitive layer. Subsequently, the transfer device transfers the toner image to the recording medium. Thereafter, the fixing device fixes the toner particles included in the toner image on the recording medium (fixing step).

[Basic toner configuration]
The toner according to the exemplary embodiment has the following basic configuration. Specifically, the toner according to the exemplary embodiment includes a plurality of toner particles. Each toner particle includes a toner core, a shell layer, and a plurality of wax particles. The shell layer contains a resin and covers a part of the surface area of the toner core. The surface of the shell layer has a sea area and a plurality of island areas each surrounded by the sea area. The sea region has a stronger hydrophobicity than each of the island regions. Each of the island regions has a charging property stronger than that of the sea region. The wax particles include core externally added wax particles. The core externally added wax particles are provided in a portion exposed from the shell layer in the surface region of the toner core. The content of wax particles in the toner is 1 part by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the resin contained in the shell layer.

  The toner having such a basic configuration has sufficient chargeability in both a normal temperature and normal humidity environment and a high temperature and high humidity environment. Further, if image formation is performed using toner having such a basic configuration, it is possible to prevent occurrence of high temperature offset. Hereinafter, the configuration of the toner according to the exemplary embodiment will be specifically described with reference to the drawings.

[Configuration of Toner According to First Specific Example]
The configuration of the toner according to the first specific example will be described with reference to FIGS. FIG. 1 is a diagram showing a cross-sectional structure of toner particles contained in a toner according to a first specific example. FIG. 2 is an enlarged view showing a part of the surface of the toner particle shown in FIG. FIG. 3 is a view showing a part of the surface structure of the toner particles shown in FIG. In FIG. 2, the radial direction of the toner particles is represented by “Dr”, the inside of the toner particles in the radial direction is represented by “X1”, and the outside of the toner particles in the radial direction is represented by “X2”.

  The toner particles 10 shown in FIG. 1 have the basic configuration described above. Therefore, the toner particles 10 have sufficient chargeability even in a normal temperature and normal humidity environment or in a high temperature and high humidity environment. Further, if image formation is performed using toner containing a plurality of toner particles 10, it is possible to prevent the occurrence of high temperature offset.

  Specifically, the toner particle 10 includes a toner core 11, a shell layer 12, and a plurality of wax particles. The shell layer 12 contains a resin. The shell layer 12 covers a part of the surface area of the toner core 11, that is, partially covers the surface area of the toner core 11. As shown in FIGS. 2 and 3, the surface of the shell layer 12 has a plurality of island-like regions R1 and sea-like regions R2. The island regions R1 are each surrounded by the sea region R2. The sea region R2 has stronger hydrophobicity than each of the island regions R1. Each of the island regions R1 has a charging property stronger than that of the sea region R2. The wax particles include core externally added wax particles 13. Each of the core externally added wax particles 13 is provided in a portion of the surface region of the toner core 11 exposed from the shell layer 12. The content of the wax particles in the toner is 1 part by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the resin (hereinafter sometimes referred to as “shell resin”) contained in the shell layer 12.

  Thus, a plurality of island regions R1 exist on the surface of the shell layer 12. Here, the island-shaped region R1 has a relatively strong chargeability. Therefore, if there are a plurality of island-like regions R1 on the surface of the shell layer 12, it is possible to impart sufficient chargeability to the toner.

  Further, on the surface of the shell layer 12, the island-shaped region R1 is surrounded by the sea-shaped region R2. Here, the sea-like region R2 has stronger hydrophobicity than the island-like region R1. Further, the plurality of island-like regions R1 have a charging property stronger than that of the sea-like region R2. For these reasons, on the surface of the shell layer 12, a relatively highly charged region is surrounded by a relatively highly hydrophobic region. Therefore, it is possible to suppress the adsorption of water molecules to the surfaces of the toner particles 10 (more specifically, the surface of the shell layer 12) not only in a normal temperature and normal humidity environment but also in a high temperature and high humidity environment. Therefore, it is considered that attenuation of the charge amount of the toner particles 10 is suppressed even in a high temperature and high humidity environment.

  If the attenuation of the charge amount of the toner particles 10 is suppressed even in a high-temperature and high-humidity environment, an image can be formed using a toner having sufficient chargeability even in a high-temperature and high-humidity environment. This makes it possible to form a high-quality image even in a high temperature and high humidity environment. For example, even when image formation is performed in a high-temperature and high-humidity environment, fogging can be prevented from occurring in the formed image.

  The wax particles include core externally added wax particles 13. Each of the core externally added wax particles 13 is provided in a portion of the surface region of the toner core 11 exposed from the shell layer 12. As described above, since the core externally added wax particles 13 are present on the outer side X2 of the toner particles 10 in the radial direction than the toner core 11, they are present on the outer side X2 of the toner particles 10 in the radial direction of the release agent contained in the toner core 11. . Therefore, in the fixing step, the core externally added wax particles 13 are more likely to function as a release agent than the release agent contained in the toner core 11. The core externally added wax particles 13 are exposed from the shell layer 12. Also by this, the core externally added wax particles 13 can function as a release agent in the fixing step. For these reasons, it is possible to prevent the occurrence of high temperature offset by forming an image using toner containing a plurality of toner particles 10. That is, the toner containing a plurality of toner particles 10 is excellent in high temperature offset resistance.

  Further, the content of the wax particles in the toner is 1 part by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the shell resin. If the content of the wax particles in the toner is 1 part by mass or more with respect to 100 parts by mass of the shell resin, it is possible to ensure the content of the wax particles (for example, the core externally added wax particles 13) that function as a release agent in the fixing process. Therefore, the high temperature offset resistance of the toner is likely to be improved. If the content of the wax particles in the toner is 35 parts by mass or less with respect to 100 parts by mass of the shell resin, it is possible to prevent the wax particles from being excessive, so that the toner is sufficiently charged in a normal temperature and humidity environment. It is easy to have sex. The content of the wax particles in the toner is preferably 1 part by mass or more and 25 parts by mass or less, and more preferably 1 part by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the shell resin. Here, the shell resin (the resin contained in the shell layer 12) includes a resin material (for example, a second resin described later) that forms the island-shaped region R1 and a resin material (for example, a first resin that is described later) that configures the sea-shaped region R2. Resin).

  The toner according to the first specific example preferably includes the toner particles 10 at a ratio of 80% by number or more, more preferably includes the toner particles 10 at a ratio of 90% by number or more, and a ratio of 100% by number. More preferably, the toner particles 10 are included. Hereinafter, the toner core 11, the shell layer 12, and the wax particles will be described in order.

<Toner core>
The toner core 11 may not contain a release agent, but preferably contains a release agent. If the toner core 11 contains a release agent, it becomes possible to provide a toner that is more excellent in high temperature offset resistance.

  The toner particles 10 include core externally added wax particles 13. Therefore, even when the content of the release agent in the toner core 11 is smaller than that of toner particles not including the core externally added wax particles 13, it is possible to provide a toner having excellent high temperature offset resistance.

<Shell layer>
(Shell layer coverage)
The ratio of the area of the toner core covered with the shell layer 12 in the surface area of the toner core 11 (hereinafter referred to as “the coverage of the shell layer 12”) is preferably 40% or more and 60% or less. When the coverage of the shell layer 12 is 40% or more, the heat resistance of the toner can be improved. When the coverage of the shell layer 12 is 60% or less, the low-temperature fixability of the toner can be improved. Further, when the coverage of the shell layer 12 is 60% or less, it is easy to secure a space in which the core externally added wax particles 13 are provided in the surface region of the toner core 11. This makes it easy to provide a toner that is excellent in high temperature offset resistance.

  When the content of the material constituting the shell layer 12 increases or when the content of the core externally added wax particles 13 decreases, the coverage of the shell layer 12 tends to increase. When the content of the material constituting the shell layer 12 decreases or when the content of the core externally added wax particles 13 increases, the coverage of the shell layer 12 tends to decrease. When the wax particles include shell-added wax particles (for example, a toner according to a third specific example to be described later), the coverage of the shell layer 12 is not limited to the content of the core-added wax particles 13 but also the shell-added wax particles 13. It tends to depend on the content of wax particles. The material constituting the shell layer 12 includes, for example, a resin material (for example, a second resin described later) that forms the island-shaped region R1 and a resin material (for example, a first resin that is described later) that configures the sea-shaped region R2. included. The coverage of the shell layer 12 can be measured by the method described in Examples described later or a method based thereon.

(Island area)
The plurality of island regions R1 are preferably scattered on the surface of the shell layer 12. This makes it possible to improve the overall charging property of the toner particles 10. Therefore, attenuation of the charge amount of the toner particles 10 in a high temperature and high humidity environment is further suppressed.

It is preferable that the occupancy ratio of the island-shaped region R1 is not less than 0.01 and not more than 0.20. As a result, the toner tends to have sufficient chargeability even in a normal temperature and normal humidity environment or in a high temperature and high humidity environment. More preferably, the occupation ratio of the island-shaped region R1 is 0.05 or more and 0.15 or less. Here, the occupation ratio of the island-shaped region R1 is the ratio of the total area SA ₁ of all the island-shaped regions R1 to the total area SB ₂ of all the sea-shaped regions R2 on the surface of the shell layer 12 (= SA ₁ / SB ₂ ).

More preferably, the content rate of the resin material (for example, 2nd resin mentioned later) which comprises island-like area | region R1 is 1 mass% or more and 20 mass% or less. As a result, the occupation ratio of the island-shaped region R1 tends to be 0.01 or more and 0.20 or less. More preferably, the content rate of the resin material which comprises island-like area | region R1 is 5 mass% or more and 15 mass% or less. Thereby, the occupation ratio of the island-shaped region R1 is likely to be 0.05 or more and 0.15 or less. Here, the content rate of the resin material which comprises island-like area | region R1 is represented by a following formula.
(Content of resin material constituting island region R1) = (Content of resin material constituting island region R1) × 100 / (Content of resin material constituting sea region R2)

(Resin particles and resin film)
As shown in FIG. 2, the shell layer 12 preferably has a plurality of resin particles 12a and a resin film 12b. More preferably, the resin particles 12a are provided so that a portion of the resin particles 12a exposed from the resin film 12b corresponds to the island-shaped region R1. More preferably, the resin film 12b is formed so that a portion of the resin film 12b exposed on the surface of the shell layer 12 corresponds to the sea region R2. Hereinafter, the resin material contained in the resin particles 12a may be referred to as “second resin”. In addition, the resin material contained in the resin film 12b may be referred to as “first resin”.

The resin particles 12a and the resin film 12b are not limited to the configuration shown in FIG. 2 (the following first example), and may be the following second example. In the first example, the surface of the protrusion corresponds to the island region R1. In the second example, the exposed portion corresponds to the island-shaped region R1.
First Example: The resin particle 12a has a protruding portion located on the radially outer side X2 of the toner particle 10 from the surface of the resin film 12b. If the particle diameter of the resin particles 12a is larger than the thickness of the resin film 12b, the first example is easily realized.
Second example: Most of the resin particles 12a are present in the resin film 12b. The surface of the resin particle 12a has an exposed portion exposed from the resin film 12b. If the particle diameter of the resin particles 12a is equal to or smaller than the thickness of the resin film 12b, the second example is easily realized.

  Further, the resin particles 12a may be in contact with the surface of the toner core 11 (see FIG. 2), or may be located on the radially outer side X2 of the toner particle 10 from the surface of the toner core 11. The thickness of the resin film 12b may be smaller (see FIG. 2) or larger than the particle diameter of the resin particles 12a. Several of the plurality of resin particles 12a may be completely buried in the resin film 12b.

  The resin film 12b may be a film having a grainy feeling (see FIG. 2) or a film having no grainy feeling. When resin particles are used as a material for forming the resin film 12b, if the material (resin particles) is completely melted and cured in a film-like form, a film without a granular feeling is formed as the resin film 12b. it is conceivable that. On the other hand, if the material (resin particles) is not completely melted and cured in a film-like form, a film having a form in which the resin particles are two-dimensionally connected (a film having a granular feeling) is formed as the resin film 12b. It is thought.

  The resin film 12b may be a single film (see FIG. 3) or an assembly of a plurality of films that are separated from each other. The resin film 12b may function as an adhesive (specifically, a reactive adhesive), and may adhere the toner core 11 and the resin particles 12a by curing. The cross-sectional shape of the resin particle 12a is not limited to the shape shown in FIG. 2, and the planar shape of the resin particle 12a is not limited to the shape shown in FIG.

When the volume median diameter (D ₅₀ ) of the toner particles 10 is 3 μm or more and 10 μm or less, 50% by number or more of the resin particles 12a have a circle equivalent diameter of 20 nm or more and 150 nm or less (a circle having the same area as the island region R1). It is preferable to have a diameter of As a result, the toner tends to have sufficient chargeability even in a normal temperature and normal humidity environment or in a high temperature and high humidity environment. More preferably, 80% by number or more of the resin particles 12a have a circle-equivalent diameter (a diameter of a circle having the same area as the island-shaped region R1) of 20 nm to 150 nm.

  The thickness of the resin film 12b is preferably 1 nm or more and 30 nm or less. If the thickness of the resin film 12b is 1 nm or more, the heat resistance of the toner can be improved. If the thickness of the resin film 12b is 30 nm or less, the low-temperature fixability of the toner can be improved. The thickness of the resin film 12b can be measured by the following method.

  First, a cross-sectional TEM photograph of toner base particles is taken using a transmission electron microscope (TEM, for example, “H-7100FA” manufactured by Hitachi High-Technologies Corporation). Next, a cross-sectional TEM photograph of the obtained toner base particles is analyzed using image analysis software (“WinROOF” manufactured by Mitani Corporation). Specifically, two straight lines that are orthogonal to each other at substantially the center of the cross section of the toner base particle are drawn. In each of the two straight lines, the length from the interface between the toner core and the resin film (corresponding to the surface of the toner core) to the surface of the resin film is measured. The average value of the four lengths thus measured is taken as the thickness of the resin film provided in one toner base particle. Such a measurement of the thickness of the resin film is performed on the plurality of toner base particles, and an average value of the thicknesses of the resin films included in the plurality of toner base particles (measurement target) is obtained. The average value of the thickness of the resin film thus obtained is defined as “resin film thickness”.

  When the boundary between the toner core and the resin film is unclear in the cross-sectional TEM photograph of the toner base particles, the cross-sectional TEM photograph of the toner base particles is converted into an electron energy loss spectroscopy (EELS) detector (“GIF TRIDIEM” manufactured by Gatan). (Registered trademark) ”) and image analysis software (“ WinROOF ”manufactured by Mitani Corporation).

(First resin and second resin)
Preferably, the first resin has a stronger hydrophobicity than the second resin, and the second resin has a stronger charging property than the first resin. More preferably, the first resin is a homopolymer or copolymer of a hydrophobic monomer, and the second resin includes a structural unit derived from a monomer having a positively charged functional group.

<Wax particles>
Each of the core externally added wax particles 13 included in the wax particles is provided in a portion of the surface region of the toner core 11 exposed from the shell layer 12. Therefore, as shown in FIG. 2, the shell layer 12 does not exist between the toner core 11 and the core externally added wax particles 13.

  When the toner particles 10 are produced according to the method described in [Method for producing toner] below, the core externally added wax particles 13 are softened and fixed to the surface of the toner core 11. Thereby, it is possible to prevent the core-added wax particles 13 from being detached from the surface of the toner core 11 during image formation (particularly before performing the fixing step). Therefore, contamination with wax can be prevented.

Preferably, the volume median diameter (D ₅₀ ) of the core externally added wax particles 13 is 10 nm or more and 150 nm or less. If the volume median diameter (D ₅₀ ) of the core externally added wax particles 13 is 10 nm or more, the core externally added wax particles 13 can be easily produced. If the volume median diameter (D ₅₀ ) of the core externally added wax particles 13 is 150 nm or less, the core externally added wax particles 13 are likely to be provided in a portion of the surface region of the toner core 11 exposed from the shell layer 12. The configuration of the toner according to the first specific example has been described above with reference to FIGS.

[Configuration of Toner According to Second Specific Example]
The configuration of the toner according to the second specific example will be described with reference to FIGS. 4 and 5. FIG. 4 is an enlarged view showing a part of the surface of the toner particles contained in the toner according to the second specific example. FIG. 5 is a diagram showing a part of the surface structure of the toner particles in the second specific example. In FIG. 4, the radial direction of the toner particles is represented by “Dr”, the radial inner side of the toner particles is represented by “X1”, and the radial outer side of the toner particles is represented by “X2”. Hereinafter, differences from the toner according to the first specific example will be mainly described.

  The toner particles 20 shown in FIG. 4 have the basic configuration described above. For this reason, the toner particles 20 have sufficient chargeability in both a normal temperature and normal humidity environment and a high temperature and high humidity environment. Further, if image formation is performed using toner containing a plurality of toner particles 20, it is possible to prevent high temperature offset.

  The toner particles 20 shown in FIG. 4 further have the following configuration. Specifically, in the toner particles 20, the surface of the inner part 131 included in the at least one core-added wax particle 13 and the side surface of the shell layer 12 are in contact with each other. On the other hand, the surface of the outer portion 133 of each of the core external additive wax particles 13 and the side surface of the shell layer 12 do not contact each other. Here, the inner portion 131 is a portion of the core externally added wax particles 13 that is located on the radially inner side X1 of the toner particles 20. The outer portion 133 is a portion of the core externally added wax particles 13 that is located on the radially outer side X2 of the toner particles 20, and is preferably a portion of the core externally added wax particles 13 excluding the inner portion 131.

  If the surface of the inner portion 131 of the at least one core externally added wax particle 13 and the side surface of the shell layer 12 are in contact with each other, the core externally added wax particle 13 is easily held by the shell layer 12. Thereby, it is easy to prevent the core externally added wax particles 13 from being detached from the surface of the toner core 11 during image formation (particularly before performing the fixing step). Therefore, it becomes easy to prevent contamination by wax. For example, it becomes easy to prevent the core externally added wax particles 13 from adhering to the surface of the constituent member of the image forming apparatus. Therefore, it becomes easy to prevent the occurrence of image defects represented by a dash mark. Further, it is easy to prevent the core externally added wax particles 13 from adhering to the surface of the carrier particles. Therefore, it becomes easy to prevent the charge amount of the toner particles 20 from being attenuated.

  When the shell layer 12 has a plurality of resin particles 12a and a resin film 12b, the surface of the inner portion 131 and the surface of the resin particle 12a are in contact with each other, so that the surface of the inner portion 131 and the side surface of the shell layer 12 are in contact with each other. Alternatively, the surface of the inner portion 131 and the side surface of the shell layer 12 may be in contact with each other by the resin film 12b covering the surface of the inner portion 131 (see FIG. 4). When the content of the material constituting the shell layer 12 increases or when the content of the core externally added wax particles 13 increases, the surface of the inner portion 131 and the side surface of the shell layer 12 tend to contact each other. Even in the toner particles 20, the shell layer 12 does not exist between the toner core 11 and the inner portion 131. More specifically, the resin particles 12a do not exist between the toner core 11 and the inner part 131, and the resin film 12b does not exist either.

  If the surface of the outer portion 133 of each of the core externally added wax particles 13 and the side surface of the shell layer 12 do not contact each other, it is possible to provide a toner having excellent high temperature offset resistance. Therefore, the toner including a plurality of toner particles 20 is excellent in high temperature offset resistance and can be easily prevented from being contaminated by wax.

  When the shell layer 12 includes a plurality of resin particles 12a and a resin film 12b, the inner portion 131 is more than the surface of the resin film 12b (more specifically, the sea region R2) of the core externally added wax particles 13. A portion located on the radially inner side X <b> 1 of the toner particles 20 is preferable. The outer portion 133 is a portion of the core externally added wax particles 13 that is located on the radially outer side X2 of the toner particles 20 from the surface of the resin film 12b (more specifically, the sea-like region R2). preferable. The configuration of the toner according to the second specific example has been described above with reference to FIGS. 4 and 5.

[Configuration of Toner According to Third Specific Example]
The configuration of the toner according to the third specific example will be described with reference to FIG. FIG. 6 is an enlarged view showing a part of the surface of the toner particles contained in the toner according to the third specific example. In FIG. 6, the radial direction of the toner particles is represented by “Dr”, the radially inner side of the toner particles is represented by “X1”, and the radially outer side of the toner particles is represented by “X2”. Hereinafter, differences from the toner according to the first specific example will be mainly described.

  The toner particles 30 shown in FIG. 6 have the basic configuration described above. For this reason, the toner particles 30 have sufficient chargeability in both a normal temperature and normal humidity environment and a high temperature and high humidity environment. Further, if image formation is performed using toner containing a plurality of toner particles 30, it is possible to prevent high temperature offset.

  The toner particles 30 shown in FIG. 6 further have the following configuration. Specifically, the toner particle 30 further includes a shell-added wax particle 23 and a shell-added wax particle 33. The shell-added wax particles 23 are wax particles that are at least partially embedded in the shell layer 12. As long as the shell layer 12 exists between the toner core 11 and the shell-added wax particles 23, the shell-added wax particles 23 may be completely embedded in the shell layer 12. The shell externally added wax particles 33 are wax particles provided on the surface of the shell layer 12. More specifically, the shell externally added wax particles 33 do not have a portion buried in the shell layer 12 and are exposed from the shell layer 12.

  A shell layer 12 exists between the toner core 11 and the shell-added wax particles 23. As described above, since the wax particles 23 in the shell are present on the outer side X2 of the toner particles 30 in the radial direction of the toner core 11, they are present on the outer side X2 of the toner particles 30 in the radial direction of the release agent contained in the toner core 11. . Therefore, in the fixing step, the shell-added wax particles 23 are more likely to function as a release agent than the release agent contained in the toner core 11. Therefore, if the toner particles 30 further contain the shell-added wax particles 23, it is possible to prevent the occurrence of high temperature offset as compared with the case where the toner particles do not contain the shell-added wax particles 23.

  The shell externally added wax particles 33 are provided on the surface of the shell layer 12. Thus, since the shell externally added wax particles 33 are present on the outer side X2 of the toner particles 30 in the radial direction than the toner core 11, they are present on the outer side X2 of the toner particles 30 relative to the release agent contained in the toner core 11. . Therefore, in the fixing step, the shell externally added wax particles 33 are more likely to function as a release agent than the release agent contained in the toner core 11. The shell externally added wax particles 33 are exposed from the shell layer 12. This also allows the shell externally added wax particles 33 to function as a release agent in the fixing step. For these reasons, when the toner particles 30 further include the shell externally added wax particles 33, it is possible to prevent the occurrence of high temperature offset as compared with the case where the toner particles do not include the shell externally added wax particles 33.

  In summary, if an image is formed using a toner containing a plurality of toner particles 30, the occurrence of high temperature offset can be further prevented.

  When the shell layer 12 includes a plurality of resin particles 12a and a resin film 12b, it is preferable that at least a part of the wax particles 23 added in the shell is embedded in the resin film 12b. The shell-added wax particles 33 may be provided on the surface of the resin particles 12a (specifically, the island-shaped region R1), or the surface of the resin film 12b (specifically, the sea-shaped region R2). ) (See FIG. 6).

  When toner particles are produced according to the method described in [Method for producing toner] below, the obtained toner particles 30 include not only the core added wax particles 13 but also the shell added wax particles 23 and the shell added wax particles 33. Furthermore, it is easy to include. The configuration of the toner according to the third specific example has been described above with reference to FIG.

[Toner Production Method]
The method for producing a toner having the above basic configuration preferably includes a toner mother particle production step, and more preferably further includes an external addition step. When the external addition step is not performed, toner base particles produced by the method described below correspond to toner particles. The toner particles produced at the same time are considered to have substantially the same configuration.

<1. Manufacturing process of toner base particles>
A preferable manufacturing process of the toner base particles includes a manufacturing process of the toner core, a preparation process of the first dispersion liquid, a preparation process of the second dispersion liquid, a preparation process of the dispersion liquid of the wax particles, and a formation process of the shell layer. Including.

(1-1. Manufacturing process of toner core)
In the production process of the toner core, it is preferable to produce the toner core by a known pulverization method or a known aggregation method. Thereby, the toner core can be easily manufactured.

(1-2. First Dispersion Preparation Process)
The first dispersion means a dispersion of particles (hereinafter referred to as “first particles”) containing a first resin (a resin for a sea-like region). In the first dispersion preparation step, it is preferable to polymerize the hydrophobic monomer in the first dispersion medium. More preferably, the hydrophobic monomer is polymerized in the presence of a polymerization initiator. One kind of hydrophobic monomer may be monopolymerized, or two or more kinds of hydrophobic monomers may be copolymerized. In this way, the first dispersion is obtained. The first dispersion medium preferably contains, for example, water (more specifically, ion exchange water).

(1-3. Preparation Step of Second Dispersion)
The second dispersion means a dispersion of particles (hereinafter referred to as “second particles”) containing a second resin (resin for island-like region). In the step of preparing the second dispersion, it is preferable to polymerize the positively chargeable monomer in the second dispersion medium. More preferably, the positively chargeable monomer is polymerized in the presence of a polymerization initiator. One positively chargeable monomer may be monopolymerized, or two or more positively chargeable monomers may be copolymerized. In this way, a second dispersion is obtained. In addition, it is preferable that a 2nd dispersion medium contains water (more specifically, ion-exchange water), for example.

(1-4. Preparation Step of Wax Particle Dispersion)
In the step of preparing the dispersion of wax particles, it is preferable to prepare a dispersion of wax particles by the following method. Specifically, the liquid containing the wax and the third solvent is stirred at the third temperature (hereinafter, the wax contained in the wax particles is referred to as “wax P”). Thereby, a solution of wax P is obtained. Thereafter, the wax P solution is emulsified. In this way, a dispersion of wax particles is obtained.

  The third temperature is preferably a temperature equal to or higher than the melting point of the wax P. More specifically, the third temperature is preferably 70 ° C. or higher and 120 ° C. or lower. The third solvent preferably contains at least one of, for example, toluene, acetone, methyl ethyl ketone, tetrahydrofuran, and water (more specifically, ion-exchanged water). If necessary, the solution of wax P may further contain a surfactant. The surfactant is preferably an anionic surfactant.

  As stirring conditions, for example, the rotational speed is preferably 50 rpm or more and 500 rpm or less, and the stirring time is preferably 1 hour or more and 5 hours or less. The emulsification treatment may be performed using at least one of a homogenizer (for example, “Ultra Turrax T50” manufactured by IKA) and a gorin type homogenizer (for example, “APV homogenizer 15M-8TA type” manufactured by SPX). preferable. The emulsification treatment is preferably performed in a high temperature environment (for example, 70 ° C. or higher and 120 ° C. or lower).

(1-5. Shell layer forming step)
In the shell layer forming step, a shell layer partially covering the surface of the toner core is formed. More specifically, the toner core, the first dispersion, the second dispersion, and the wax particle dispersion are mixed at a predetermined temperature. Thereby, a shell layer is formed in a part of the surface area of the toner core, and wax particles (core-added wax particles) are provided in a part of the remaining area. In addition, a part of the wax particles excluding the core externally added wax particles may be embedded in the shell layer. In addition, wax particles other than the core externally added wax particles may be provided on the surface of the shell layer. In this way, a dispersion of toner base particles is obtained. A plurality of toner base particles can be obtained by subjecting the obtained dispersion of toner base particles to solid-liquid separation, washing and drying.

(1-5-1. Preparation Step of Dispersion Y)
Specifically, first, the toner core, the first dispersion, the second dispersion, and the wax particle dispersion are mixed to obtain a dispersion Y.

  The first particles, the second particles, and the wax particles each adhere to the surface of the toner core in the dispersion Y. In order to uniformly adhere the first particles, the second particles, and the wax particles to the surface of the toner core, it is preferable that the toner core is highly dispersed in the dispersion Y. In order to highly disperse the toner core in the dispersion Y, the dispersion Y may contain a surfactant, or dispersed using a powerful stirring device (for example, “Hibis Disper Mix” manufactured by Primics Co., Ltd.). Liquid Y may be stirred.

When the blending amount of the second dispersion is excessive, the blending amount of the second resin is excessive, and the charge retention property of the toner in a high temperature and high humidity environment may be insufficient. Therefore, it is preferable to adjust the amount of the second dispersion so that the amount of the second resin is not excessive. Specifically, the blending ratio of the second resin represented by the following formula is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less.
(Blend ratio of second resin) = (Blend quantity of second resin) × 100 / (Blend quantity of first resin)

  Preferably, the pH of the dispersion Y is adjusted to 3 or more and 5 or less using, for example, hydrochloric acid. Thereby, formation of a shell layer can be promoted. When a dispersion of toner base particles is obtained, it is preferable to neutralize the dispersion of toner base particles using, for example, sodium hydroxide.

(1-5-2. Mixing step at a predetermined temperature)
Next, while stirring the dispersion liquid Y, the temperature of the dispersion liquid Y is raised to a predetermined temperature at a predetermined temperature increase rate. Thereafter, while stirring the dispersion Y, the temperature of the dispersion Y is maintained at a predetermined temperature over a predetermined time. The predetermined temperature is preferably in the vicinity of the glass transition point of the first resin, preferably less than the glass transition point of the second resin, and preferably less than the melting point of the wax P. Therefore, it is considered that the following occurs while the temperature of the dispersion Y is maintained at a predetermined temperature.

Specifically, if the predetermined temperature is in the vicinity of the glass transition point of the first resin, the first particles are dissolved in the dispersion Y and cured in a film form. In this way, a resin film (for example, the resin film 12b shown in FIG. 2) is formed. Here, “the predetermined temperature being in the vicinity of the glass transition point of the first resin” preferably means that the predetermined temperature and the glass transition point of the first resin satisfy the following expression.
−5 ° C. ≦ (Glass transition point of first resin) − (predetermined temperature) ≦ + 5 ° C.

  Further, if the predetermined temperature is lower than the glass transition point of the second resin, the second particles exist in the form of particles without being dissolved in the dispersion Y. However, since the predetermined temperature is high, the toner core is softened. The second particles are fixed to the surface of the toner core by the softening of the toner core. That is, the second particles become resin particles (for example, resin particles 12a shown in FIG. 2). Since the first particles are cured in a film form, the resin particles are easily surrounded by the resin film. Here, “the predetermined temperature is lower than the glass transition point of the second resin” preferably means that the difference between the glass transition point of the second resin and the predetermined temperature is more than 5 ° C. . More preferably, the difference between the glass transition point of the second resin and the predetermined temperature is 6 ° C. or more and 20 ° C. or less.

  If the predetermined temperature is lower than the melting point of the wax P, the wax particles exist in the form of particles in the dispersion Y without being dissolved. However, the predetermined temperature is high. Therefore, the wax particles are softened. In addition, the toner core is softened. By this softening, at least one wax particle (more specifically, the core externally added wax particle) is fixed to the surface of the toner core. Since the first particles are cured in the form of a film, the surface of the inner part of the core-added wax particles and the side surface of the shell layer may come into contact with each other. In addition, some of the wax particles excluding the core externally added wax particles may be fixed on the surface of the shell layer. Here, “the predetermined temperature being lower than the melting point of the wax P” preferably means that the difference between the melting point of the wax P and the predetermined temperature is 3 ° C. or more. More preferably, the difference between the melting point of the wax P and the predetermined temperature is 3 ° C. or higher and 20 ° C. or lower.

  The predetermined temperature is preferably a temperature selected from 50 ° C to 70 ° C. If the predetermined temperature is 50 ° C. or higher, the first particles are easily dissolved in the dispersion Y. If the predetermined temperature is 70 ° C. or lower, it is possible to prevent the second particles from being dissolved in the dispersion Y. Further, if the predetermined temperature is 70 ° C. or less, the predetermined temperature is likely to be lower than the melting point of the wax P, so that it is possible to prevent the wax particles from being dissolved in the dispersion Y. Moreover, if predetermined temperature is 70 degrees C or less, it can prevent that a resin component melt | dissolves due to formation of a shell layer. The resin component includes a binder resin contained in the toner core.

  The predetermined heating rate is preferably a speed selected from, for example, 0.1 ° C./min to 3 ° C./min. The predetermined time is preferably, for example, a time selected from 30 minutes to 4 hours. It is preferable to stir the dispersion Y under the condition that the rotation speed is 50 rpm or more and 500 rpm or less.

<2. External process>
The toner base particles and the external additive are mixed using a mixer (for example, an FM mixer manufactured by Nippon Coke Kogyo Co., Ltd.). As a result, each of the external additive particles adheres to the surface of the toner base particles. In this way, a toner including a plurality of toner particles including toner base particles and an external additive is obtained.

[Examples of materials and physical properties constituting toner]
The toner includes a plurality of toner particles. Each toner particle includes a toner core, a shell layer, and wax particles. Hereinafter, the toner core, the shell layer, and the wax particles will be described in order.

<Toner core>
The toner core contains a binder resin. The toner core may further contain at least one of a colorant, a charge control agent, and a release agent.

(Binder resin)
In the toner core, the binder resin generally 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.

  Moreover, the property (specifically, hydroxyl value, acid value, glass transition point, or softening point) of the binder resin can be adjusted by using a combination of a plurality of types of resins as the binder resin. For example, when the binder resin has an ester group, a hydroxyl group, an ether group, an acid group, or a methyl group, the toner core tends to become anionic. Further, when the binder resin has an amino group or an amide group, the toner core tends to be cationic.

  The toner core preferably contains a thermoplastic resin. As the thermoplastic resin, for example, polyester resin, styrene resin, acrylic acid resin, olefin resin, vinyl resin, polyamide resin, or urethane resin can be used. As the acrylic resin, for example, an acrylic ester polymer or a methacrylic ester polymer can be used. As the olefin resin, for example, a polyethylene resin or a polypropylene resin can be used. As the vinyl resin, for example, vinyl chloride resin, polyvinyl alcohol, vinyl ether resin, or N-vinyl resin can be used. A copolymer of each of these resins, that is, a copolymer in which an arbitrary repeating unit is introduced into the resin, can also be used as the thermoplastic resin constituting the toner particles. For example, a styrene-acrylic acid resin or a styrene-butadiene resin can also be used as the thermoplastic resin constituting the toner core. Below, the polyester resin which is an example of binder resin is explained in full detail.

(Binder resin: Polyester resin)
The polyester resin is a copolymer of one or more alcohols and one or more carboxylic acids. As alcohol for synthesizing a polyester resin, the following dihydric alcohol or trihydric or higher alcohol can be used, for example. As the dihydric alcohol, for example, diols or bisphenols can be used. As the carboxylic acid for synthesizing the polyester resin, for example, the following divalent carboxylic acids or trivalent or higher carboxylic acids can be used.

  Preferable examples of diols include aliphatic diols. Suitable examples of the aliphatic diol include diethylene glycol, triethylene glycol, neopentyl glycol, 1,2-propanediol, α, ω-alkanediol, 2-butene-1,4-diol, 1,4-cyclohexanedi Examples include methanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene glycol. α, ω-alkanediol includes, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1, 8-octanediol, 1,9-nonanediol, or 1,12-dodecanediol is preferred.

  Preferable examples of the bisphenol include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, or bisphenol A propylene oxide adduct.

  Preferable examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane. Triol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, or 1,3,5- Trihydroxymethylbenzene is mentioned.

  Preferable examples of the divalent carboxylic acid include aromatic dicarboxylic acid, α, ω-alkane dicarboxylic acid, unsaturated dicarboxylic acid, and cycloalkane dicarboxylic acid. The aromatic dicarboxylic acid is preferably, for example, phthalic acid, terephthalic acid, or isophthalic acid. The α, ω-alkanedicarboxylic acid is preferably, for example, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, or 1,10-decanedicarboxylic acid. The unsaturated dicarboxylic acid is preferably, for example, maleic acid, fumaric acid, citraconic acid, itaconic acid, or glutaconic acid. The cycloalkane dicarboxylic acid is preferably, for example, cyclohexane dicarboxylic acid.

  Preferred examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) Examples include methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or empole trimer acid.

(Binder resin: crystalline polyester resin)
The crystalline polyester resin preferably contains an α, ω-alkanediol having 2 to 8 carbon atoms as an alcohol component. The α, ω-alkanediol is preferably, for example, two types of α, ω-alkanediol. More specifically, the α, ω-alkanediol is preferably 1,4-butanediol having 4 carbon atoms and 1,6-hexanediol having 6 carbon atoms.

  The crystalline polyester resin preferably contains α, ω-alkanedicarboxylic acid having 4 to 10 carbon atoms (including carbon of two carboxyl groups) as an acid component. The α, ω-alkanedicarboxylic acid is preferably, for example, succinic acid having 4 carbon atoms.

  More preferably, the melting point (Mp) of the crystalline polyester resin is 50 ° C. or higher and 100 ° C. or lower. Thereby, it is possible to provide a toner that is further excellent in low-temperature fixability and heat-resistant storage stability.

  The amount of the crystalline polyester resin contained in the toner core is 1% by mass or more and 50% by mass or less with respect to the total amount of the polyester resin contained in the toner core (the total amount of the crystalline polyester resin and the amorphous polyester resin). It is preferably 5% by mass or more and 25% by mass or less. For example, when the total amount of the polyester resin contained in the toner core is 100 g, the amount of the crystalline polyester resin contained in the toner core is preferably 1 g or more and 50 g or less (more preferably 5 g or more and 25 g or less). Thereby, it is possible to provide a toner that is further excellent in low-temperature fixability and heat-resistant storage stability.

(Binder resin: Amorphous polyester resin)
The amorphous polyester resin preferably contains bisphenols as an alcohol component. The bisphenol is preferably at least one of, for example, a bisphenol A ethylene oxide adduct and a bisphenol A propylene oxide adduct.

  The amorphous polyester resin preferably contains at least one of an aromatic dicarboxylic acid and an unsaturated dicarboxylic acid as an acid component. The aromatic dicarboxylic acid is preferably terephthalic acid, for example. The unsaturated dicarboxylic acid is preferably fumaric acid, for example.

(Coloring agent)
As the colorant, a known pigment or dye can be used according to the color of the toner. In order to form a high-quality image using toner, the amount of the colorant is preferably 1 part by mass or more and 20 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.

  As the yellow colorant, for example, one or more compounds selected from the group consisting of condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds can be used. Examples of the yellow colorant 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 can be used.

  The magenta colorant is, for example, selected from the group consisting of condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. One or more compounds can be used. Examples of the magenta colorant 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).

  As the cyan colorant, for example, one or more compounds selected from the group consisting of a copper phthalocyanine compound, an anthraquinone compound, and a basic dye lake compound can be used. 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 can be used.

(Release agent)
The release agent is used, for example, for the purpose of improving the fixing property or high temperature 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.

  The mold release agent is, for example, an aliphatic hydrocarbon wax, a vegetable wax, an animal wax, a mineral wax, a wax mainly composed of a fatty acid ester, or a wax obtained by deoxidizing a part or all of the fatty acid ester. Is preferred. The aliphatic hydrocarbon wax is preferably, for example, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, or Fischer-Tropsch wax. Aliphatic hydrocarbon waxes also contain these oxides. The vegetable wax is preferably, for example, candelilla wax, carnauba wax, wood wax, jojoba wax, or rice wax. The animal wax is preferably, for example, beeswax, lanolin, or whale wax. The mineral wax is preferably, for example, ozokerite, ceresin, or petrolatum. Waxes mainly composed of fatty acid esters are preferably, for example, montanic acid ester wax or caster wax. One type of release agent may be used alone, or multiple types of release agents may be used in combination.

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

(Charge control agent)
The charge control agent is used, for example, for the purpose of improving the charge stability or charge rising property of the toner. The charge rising characteristic of the toner is an index as to whether or not the toner can be charged to a predetermined charge level in a short time.

  By adding a negatively chargeable charge control agent to the toner core, the anionicity of the toner core can be enhanced. Further, the cationic property of the toner core can be increased by including a positively chargeable charge control agent in the toner core. However, if sufficient chargeability is ensured in the toner, it is not necessary to include a charge control agent in the toner core.

<Shell layer>
The shell layer preferably has a resin film and a plurality of resin particles. The resin film preferably contains a first resin. Each of the resin particles preferably contains a second resin. The first resin preferably has stronger hydrophobicity than the second resin. The second resin preferably has a stronger charging property than the first resin.

(First resin)
The first resin is preferably a homopolymer or copolymer of a hydrophobic monomer, more preferably at least one of a styrene resin, an acrylic acid resin, and a styrene-acrylic acid resin. The styrene resin is a polymer of one or more styrene monomers. The acrylic resin is a polymer of one or more acrylic acid monomers. The styrene-acrylic acid resin is a copolymer of one or more styrene monomers and one or more acrylic monomers.

  Preferable examples of the styrenic monomer include styrene, alkyl styrene, hydroxystyrene, and halogenated styrene. The alkyl styrene is preferably, for example, α-methyl styrene, m-methyl styrene, p-methyl styrene, p-ethyl styrene, or 4-tert-butyl styrene. Hydroxystyrene is preferably, for example, p-hydroxystyrene or m-hydroxystyrene. The halogenated styrene is preferably, for example, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, or p-chlorostyrene. More preferably, the styrenic monomer is styrene, alkyl styrene, or halogenated styrene.

  Preferable examples of the acrylic acid monomer include (meth) acrylic acid, (meth) acrylonitrile, (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. More preferably, the acrylic acid monomer is (meth) acrylonitrile or (meth) acrylic acid alkyl ester.

  More specifically, the first resin is, for example, a copolymer of styrene and n-butyl (meth) acrylate, styrene, n-butyl (meth) acrylate, and a hydroxyalkyl ester of (meth) acrylic acid. A copolymer or a copolymer of styrene, n-butyl (meth) acrylate, and acrylonitrile is preferable.

(Second resin)
The second resin preferably contains a structural unit derived from a charge control agent. When the toner has a positive chargeability, the second resin preferably contains a structural unit derived from a positively chargeable charge control agent, more preferably a co-polymer of a positive chargeability charge control agent and an acrylic monomer. It is a polymer.

  The positively chargeable charge control agent is preferably, for example, a nitrogen-containing vinyl compound. The nitrogen-containing vinyl compound is preferably, for example, a benzyldecylhexylmethylammonium salt, a decyltrimethylammonium salt, or a (meth) acryloyl group-containing quaternary ammonium salt. The (meth) acryloyl group-containing quaternary ammonium salt is preferably, for example, a (meth) acrylamidoalkyltrimethylammonium salt or a (meth) acryloyloxyalkyltrimethylammonium salt. More specifically, the (meth) acrylamide alkyltrimethylammonium salt is preferably (3-acrylamidopropyl) trimethylammonium chloride, for example. More specifically, the (meth) acryloyloxyalkyltrimethylammonium salt is preferably 2- (methacryloyloxy) ethyltrimethylammonium chloride, for example.

  The acrylic monomer that can be used as the monomer constituting the second resin is preferably the acrylic monomer described in the above (first resin).

<Wax particles>
The wax P contained in the wax particles is not particularly limited, and the materials described in the above (release agent) can be used. More specifically, the wax contained in the core externally added wax particles is not particularly limited, and the materials described in the above (release agent) can be used. Further, when the wax particles include the shell-added wax particles, the wax contained in the shell-added wax particles is not particularly limited, and the materials described in the above (release agent) can be used. The volume median diameter of the shell added wax particles (D _50), as well as the volume median diameter of the core externally added wax particles (D _50), is preferably 10nm or more 150nm or less. Further, when the wax particles include the shell externally added wax particles, the wax contained in the shell externally added wax particles is not particularly limited, and the materials described above (release agent) can be used. The volume median diameter of the shell externally added wax particles (D _50), as well as the volume median diameter of the core externally added wax particles (D _50), it is preferably 10nm or more 150nm or less.

  Examples of the present invention will be described. Table 1 shows toners T-1 to T-9 (each toner for developing an electrostatic latent image) according to Examples or Comparative Examples.

In Table 1, the suspension A means a suspension containing the first particles. For the solid content of the suspension A, a value calculated by the following equation is described.
Suspension A solid content (unit: g) = Suspension A blending amount (unit: g) × Suspension A solid content concentration (unit: mass%) / 100

The suspension B means a suspension including second particles. For the solid content of the suspension B, a value calculated by the following equation is described.
Suspension B solid content (unit: g) = Suspension B blending amount (unit: g) × Suspension B solid content concentration (unit: mass%) / 100

A value calculated by the following equation is described as the solid content of the dispersion of wax particles.
Content of solid content of wax particle dispersion (unit: g) = blending amount of wax particle dispersion (unit: g) × solid content concentration of wax particle dispersion (unit: mass%) / 100

W / (A + B) describes the content of the wax particles when the content of the shell resin is 100 parts by mass. More specifically, W / (A + B) is a value calculated by the following formula.
Wax particle content (unit: parts by mass) = (solid content in wax particle dispersion) × 100 / [(suspension A solid content) + (suspension B solid content) ]

  Hereinafter, a manufacturing method, an evaluation method, and an evaluation result of toners T-1 to T-9 (each toner for developing an electrostatic latent image) according to Examples or Comparative Examples will be described in order. In the evaluation in which an error occurs, a considerable number of measurement values with sufficiently small errors are obtained, and the arithmetic average of the obtained measurement values is used as the evaluation value. Moreover, the transmission electron microscope (TEM) was used for the measurement of a number average particle diameter. Moreover, the measuring methods of Tg (glass transition point) and Tm (softening point) are as follows unless otherwise specified.

<Measurement method of Tg>
A differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.) was used to determine the endothermic curve of the sample (eg, resin). Subsequently, the Tg (glass transition point) of the sample was read from the obtained endothermic curve. The temperature of the specific heat change point (intersection of the extrapolation line of the base line and the extrapolation line of the falling line) in the obtained endothermic curve corresponds to the Tg (glass transition point) of the sample.

<Tm measurement method>
A sample (for example, resin) is set on a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation), a die pore diameter of 1 mm, a plunger load of 20 kg / cm ² , and a temperature rising rate of 6 ° C./min. Then, a 1 cm ³ sample was melted and discharged, and an S-shaped curve (horizontal axis: temperature, vertical axis: stroke) of the sample was obtained. Subsequently, the Tm (softening point) of the sample was read from the obtained S-shaped curve. In the obtained S-curve, if the maximum stroke value is S ₁ and the low-temperature baseline stroke value is S ₂ , the stroke value in the S-curve is “(S ₁ + S ₂ ) / 2”. Corresponds to the Tm (softening point) of the sample.

[Production Method of Toner T-1]
(Production of toner core)
750 g of low viscosity polyester resin (Tg = 38 ° C., Tm = 65 ° C.), 100 g of medium viscosity polyester resin (Tg = 53 ° C., Tm = 84 ° C.), high viscosity polyester resin (Tg = 71 ° C., Tm = 120 ° C.) ) 150 g, Carnauba wax (“Carnauba wax No. 1” manufactured by Kato Yoko Co., Ltd.), and colorant (“KET BLUE 111” manufactured by DIC Corporation, phthalocyanine blue) 40 g are mixed with an FM mixer (Nippon Coke Industrial Co., Ltd.). Was used at a rotational speed of 2400 rpm.

Subsequently, the obtained mixture was mixed with a material supply speed of 5 kg / hour, a shaft rotation speed of 160 rpm, and a set temperature range (cylinder temperature) of 100 ° C. or higher using a twin-screw extruder (“PCM-30” manufactured by Ikegai Co., Ltd.). It was melt-kneaded under conditions of 130 ° C. or lower. Subsequently, the obtained melt-kneaded product was cooled, and the cooled melt-kneaded product was coarsely pulverized using a pulverizer (“Rotoplex (registered trademark) 16/8 type” manufactured by Hosokawa Micron Corporation). Subsequently, the obtained coarsely pulverized product was finely pulverized using a jet mill (“Ultrasonic Jet Mill Type I” manufactured by Nippon Pneumatic Industry Co., Ltd.). Subsequently, the obtained finely pulverized product was classified using a classifier (“Elbow Jet EJ-LABO type” manufactured by Nippon Steel Mining Co., Ltd.). As a result, a toner core having a volume median diameter (D ₅₀ ) of 6 μm was obtained.

(Preparation of suspension A)
A 1 L three-necked flask equipped with a thermometer and a stirring blade was set in a water bath, and 875 mL of ion-exchanged water and an anionic surfactant (“Latemul (registered trademark) WX” manufactured by Kao Corporation, components: 75 mL of polyoxyethylene alkyl ether sodium sulfate, solid content concentration: 26% by mass). Thereafter, while stirring the flask contents at a rotation speed of 100 rpm, the temperature in the flask was raised to 80 ° C. using a water bath, and then kept at that temperature (80 ° C.). Subsequently, two kinds of liquids (first liquid and second liquid) were dropped into the contents of the flask at 80 ° C. over 5 hours. The first liquid was a mixed liquid of 18 g of styrene and 2 g of butyl acrylate. The second liquid was a solution in which 0.5 g of potassium persulfate was dissolved in 30 mL of ion exchange water. Subsequently, the temperature in the flask was kept at 80 ° C. for another 2 hours to polymerize the flask contents. As a result, a suspension (suspension A) of resin fine particles (hydrophobic resin) was obtained. The solid content concentration of the suspension A was 2% by mass. The resin fine particles contained in the suspension A had a number average particle diameter of 32 nm and Tg of 71 ° C.

(Preparation of suspension B)
In a 1 L three-necked flask equipped with a thermometer, a condenser tube, a nitrogen inlet tube, and a stirring blade, 90 mL of isobutanol, 100 g of methyl methacrylate, 35 g of butyl acrylate, and 2- (methacryloyloxy) ethyl 30 g of trimethylammonium chloride (Alfa Aesar), 6 mL of 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) propionamide) (“VA-086” manufactured by Wako Pure Chemical Industries, Ltd.) Put. Subsequently, the flask contents were reacted for 3 hours with stirring at a rotational speed of 100 rpm under a nitrogen atmosphere and a temperature of 80 ° C. Then, 3 mL of 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) propionamide) (“VA-086” manufactured by Wako Pure Chemical Industries, Ltd.) was added into the flask, and the nitrogen atmosphere and temperature were increased. The flask contents were further reacted for 3 hours under the condition of 80 ° C. to obtain a liquid containing a polymer. Subsequently, the liquid containing the obtained polymer was dried under a reduced pressure atmosphere and a temperature of 150 ° C. Subsequently, the dried polymer was crushed to obtain a positively chargeable resin.

  Subsequently, 200 g of the positively chargeable resin obtained as described above and ethyl acetate (Wako Pure Chemical Industries, Ltd.) were placed in a container of a mixing apparatus (“Hibismix (registered trademark) 2P-1 type” manufactured by PRIMIX Corporation). 184 mL of “Ethyl acetate special grade” manufactured by the company was added. Subsequently, the container contents were stirred for 1 hour at a rotation speed of 20 rpm to obtain a highly viscous solution. Thereafter, an aqueous solution such as ethyl acetate was added to the resulting highly viscous solution. Here, the aqueous solution of ethyl acetate and the like was 1 mL of hydrochloric acid 18 mL, an anionic surfactant (“Emar (registered trademark) 0” manufactured by Kao Corporation, component: sodium lauryl sulfate) 20 g, and ethyl acetate (Wako Pure Chemical Industries, Ltd.). It was an aqueous solution prepared by dissolving 16 g of “ethyl acetate special grade” in 562 mL of ion-exchanged water.

  When an aqueous solution such as ethyl acetate was added to the high-viscosity solution, a suspension (suspension B) of positively chargeable resin fine particles (charge control agent-containing resin) was obtained. The solid content concentration of the suspension B was 20% by mass. The resin fine particles contained in the suspension B had a number average particle size of 35 nm and Tg of 80 ° C.

(Preparation of wax particle dispersion W-1)
In a stirrer equipped with a stirring blade, 40 parts by mass of ester wax (“Nissan Electol (registered trademark) WEP-3” manufactured by NOF Corporation, melting point: 73 ° C.) and 1 part by mass of sodium dodecylbenzenesulfonate (Anionic surfactant) and 59 parts by mass of ion-exchanged water were added. While stirring the contents of the stirrer at a rotation speed of 100 rpm, the temperature in the stirrer was raised to 90 ° C. While maintaining the temperature in the stirrer at 90 ° C., the stirrer was stirred while stirring the contents of the stirrer at a rotational speed of 9500 rpm for 5 minutes using a homogenizer (“Ultra Turrax T50” manufactured by IKA). The contents of were emulsified. The temperature in the stirring apparatus was raised to 100 ° C. While maintaining the temperature in the stirrer at 100 ° C., the content of the stirrer is emulsified at a pressure of 400 kg / cm ² using a Gorin type homogenizer (“APV homogenizer 15M-8TA type” manufactured by SPX). Went further. In this way, a dispersion W-1 of wax particles was obtained. The solid content concentration of the dispersion W-1 of wax particles was 40% by mass. For the wax particles contained in the wax particle dispersion W-1, the volume median diameter (D ₅₀ ) is measured using a laser diffraction / scattering particle size distribution analyzer (“LA-950V2” manufactured by Horiba, Ltd.). did. The volume median diameter (D ₅₀ ) of the wax particles was 20 nm. The obtained wax particles had a sharp particle size distribution. More specifically, the wax particles obtained contained substantially only wax particles having a particle size of about 20 nm.

(Formation of shell layer)
A 1 L three-necked flask equipped with a thermometer and a stirring blade was set in a water bath, and 100 mL of ion-exchanged water was placed in the flask. Thereafter, the temperature in the flask was kept at 30 ° C. using a water bath. Subsequently, dilute hydrochloric acid was added to the flask to adjust the pH of the flask contents to 4. Subsequently, in the flask, 220 g of suspension A (solid content concentration: 2% by mass), 1.2 g of suspension B (solid content concentration: 20% by mass), and a dispersion W-1 of wax particles (solid content concentration: 40 mass%) 1.30 g was added.

  Subsequently, 300 g of the toner core prepared by the above-described procedure was added to the flask, and the flask contents were stirred for 1 hour at a rotation speed of 200 rpm. Thereafter, 300 mL of ion exchange water was added into the flask. Subsequently, while stirring the flask contents at a rotation speed of 100 rpm, the temperature in the flask was increased to 70 ° C. at a rate of 1 ° C./min. Subsequently, the flask contents were stirred for 2 hours under the conditions of a temperature of 70 ° C. and a rotation speed of 100 rpm.

  Subsequently, sodium hydroxide was added to the flask to adjust the pH of the flask contents to 7. Subsequently, the flask contents were cooled until the temperature reached room temperature (about 25 ° C.) to obtain a dispersion liquid containing toner mother particles.

(Washing process)
The dispersion of toner base particles obtained as described above was filtered (solid-liquid separation) using a Buchner funnel to obtain wet cake-like toner base particles. Thereafter, the obtained wet cake-like toner base particles were redispersed in ion-exchanged water. Further, dispersion and filtration were repeated 5 times to wash the toner base particles.

(Drying process)
Subsequently, the obtained toner base particles were dispersed in an aqueous ethanol solution having a concentration of 50% by mass. As a result, a slurry of toner base particles was obtained. Subsequently, the toner base particles in the slurry were removed under the conditions of a hot air temperature of 45 ° C. and a blower air volume of 2 m ³ / min using a continuous surface reformer (“Coat Mizer (registered trademark)” manufactured by Freund Sangyo Co., Ltd.). Dried. As a result, toner mother particle powder was obtained. As a result of observing the dried toner base particles using a scanning electron microscope (SEM), a granular feeling was observed in the shell layer, but the particles constituting the shell layer were not separated. Further, it was confirmed that the toner base particles contained core-added wax particles, shell-added wax particles, and shell-added wax particles.

(External addition process)
Subsequently, the obtained toner base particles were externally added. Specifically, 100 parts by mass of toner base particles and 1 part by mass of dry silica fine particles (“AEROSIL (registered trademark) REA90” manufactured by Nippon Aerosil Co., Ltd.) and a 10 L capacity FM mixer (manufactured by Nippon Coke Industries, Ltd.) Was added for 5 minutes to adhere the external additive (silica particles) to the surface of the toner base particles. Thereafter, the obtained toner was sieved using a sieve of 200 mesh (aperture 75 μm). As a result, Toner T-1 containing a large number of toner particles was obtained.

[Production Method of Toners T-2 to T-4]
Toners T-2 and T-3 were produced in accordance with the production method of toner T-1, except that the blending amount of the wax particle dispersion was changed to the values shown in Table 1. Toner T-4 was produced according to the production method of toner T-1, except that the blending amount of suspension B was changed to the values shown in Table 1.

[Production Method of Toner T-5]
Toner T-5 was manufactured according to the manufacturing method of toner T-1, except that the wax particle dispersion W-2 prepared by the following method was used.

(Preparation of wax particle dispersion W-2)
In a stirrer equipped with a stirring blade, 40.0 parts by mass of carnauba wax (“Carnauba Wax No. 1” manufactured by Hiroyuki Kato, melting point: 88 ° C.) and 0.5 parts by mass of sodium dodecylbenzenesulfonate ( Anionic surfactant) and 59.5 parts by mass of ion-exchanged water were added. Thereafter, a wax particle dispersion W-2 was obtained according to the method for preparing the wax particle dispersion W-1. The solid content concentration of the dispersion W-2 of wax particles was 40% by mass. For the wax particles contained in the wax particle dispersion W-2, the volume median diameter (D ₅₀ ) is measured using a laser diffraction / scattering particle size distribution analyzer (“LA-950V2” manufactured by Horiba, Ltd.). did. The volume median diameter (D ₅₀ ) of the wax particles was 50 nm. The obtained wax particles had a sharp particle size distribution. More specifically, the wax particles obtained contained substantially only wax particles having a particle size of about 50 nm.

[Production Method of Toners T-6 to T-9]
Toner T-6 was produced according to the production method of toner T-1, except that the dispersion of wax particles was not used. A toner T-7 was produced according to the production method of the toner T-1, except that the suspension B was not used. Toner T-8 was manufactured according to the manufacturing method of toner T-1, except that the blending amount of suspension B was changed to the values shown in Table 1. Toner T-9 was produced according to the production method of toner T-1, except that the blending amount of the wax particle dispersion was changed to the values shown in Table 1.

[Measuring Method of Physical Property Values of Toners T-1 to T-9]
The covering rate of the shell layer was measured by the method shown below. When measuring the coverage of the shell layer, toner particles from which the external additive was removed (that is, toner base particles) were used as samples. The measurement results are shown in Table 2.

<Measurement of shell layer coverage>
First, the toner base particles were exposed for 20 minutes in 2 mL of RuO ₄ aqueous solution (concentration: 5% by mass) in a normal temperature (25 ° C.) air atmosphere. The toner base particles dyed in this way are observed using a field emission scanning electron microscope (FE-SEM) (“JSM-7600F” manufactured by JEOL Ltd.), and a reflected electron image of the toner base particles. Got. Of the surface area of the toner core, the area covered with the shell layer was more easily dyed with ruthenium (Ru) than the area not covered with the shell layer. Therefore, in the obtained backscattered electron image, in the surface area of the toner core, the area covered with the shell layer was observed brighter than the area not covered with the shell layer. The observation with the field emission scanning electron microscope was performed under the condition that the acceleration voltage was 10.0 kV and the irradiation current was about 95 pA. In addition, photographing with a field emission scanning electron microscope was performed under the condition that the magnification was 50000 times, the contrast was 4800, and the brightness was constant at 550.

In the obtained reflected electron image, the brightness value was divided into 256, with the brightest value being 255 and the darkest value being 0. Then, using the image analysis software (“WinROOF” manufactured by Mitani Shoji Co., Ltd.), the binarization process based on the luminance value 144 was performed on the reflected electron image. After binarization processing, the area SC _{1 of the} entire reflected electron image of the toner base particles (corresponding to the total number of pixels in the reflected electron image) and the area SD ₂ of the region having a luminance value of 144 or more in the reflected electron image (reflected) Corresponding to the number of pixels having a luminance value of 144 or more in the electronic image), and the covering rate (unit:%) of the shell layer was calculated according to the following formula.
Cover rate of shell layer = 100 × area SD ₂ / area SC ₁

[Evaluation method]
The charge decay characteristics, charge amount, low-temperature fixability, and high-temperature offset resistance of the toner (toners T-1 to T-9) were evaluated by the following methods. The results are shown in Table 3.

<Charge decay characteristics>
The charge decay constant α of the samples (toners T-1 to T-9) is measured using an electrostatic diffusivity measuring device (“NS-D100” manufactured by Nano Seeds Co., Ltd.), JIS (Japanese Industrial Standard) C 61340-2-1. -Measured in accordance with 2006. Hereinafter, a method for measuring the charge decay constant of the toner will be described in detail.

  A sample was placed in the measurement cell. The measurement cell was a metal cell in which a recess having an inner diameter of 10 mm and a depth of 1 mm was formed. The sample was pushed in from above using a slide glass, and the concave portion of the cell was filled with the sample. The sample overflowed from the cell was removed by reciprocating the slide glass on the surface of the cell. The filling amount of the sample was 0.04 g or more and 0.06 g or less.

Subsequently, the measurement cell filled with the sample was allowed to stand for 12 hours in an environment of a temperature of 32 ° C. and a humidity of 80% RH. Subsequently, the grounded measurement cell was placed in an electrostatic diffusivity measuring apparatus, and ions were supplied to the sample by corona discharge to charge the sample. The charging time was 0.5 seconds. And after 0.7 second passed after completion | finish of corona discharge, the surface potential of the sample was measured continuously. Based on the measured surface potential and the formula “V = V ₀ exp (−α√t)”, the charge decay constant (charge decay rate) α was calculated. In the formula, V represents the surface potential [V], V ₀ represents the initial surface potential [V], and t represents the decay time [second].

  When the charge decay constant α (constant α described in Table 3) was 0.020 or less, it was evaluated as very good, and when the charge decay constant α exceeded 0.025, it was evaluated as bad.

<Charge amount>
A developer carrier (a carrier for “TASKalfa 5550ci” manufactured by Kyocera Document Solutions Co., Ltd.) and a sample (toners T-1 to T-9) are mixed for 30 minutes using a ball mill, and a developer for evaluation (two components) Developer) was prepared. The ratio of the sample (toner) in the developer for evaluation was 12% by mass.

  Subsequently, the developer for evaluation which was allowed to stand for 24 hours in a normal temperature and normal humidity environment (N / N environment: temperature 23 ° C., humidity 50% RH), and a high temperature and high humidity environment (H / H environment: temperature 32.5 ° C.). And the developer for evaluation that was allowed to stand for 24 hours under a humidity of 80% RH), the charge amount of the toner in the developer was measured. The charge amount of the toner in the developer was measured using a Q / m meter (“MODEL 210HS-1” manufactured by Trek) under the following conditions.

<Measurement method of charge amount of toner in developer>
A developer was put into a measurement cell of a Q / m meter, and only the toner out of the put developer was sucked through a sieve for 10 seconds. Then, based on the formula “total electric amount of sucked toner (unit: μC) / mass of sucked toner (unit: g)”, the charge amount of toner in the developer (unit: μC / g) is calculated. Calculated.

  It was evaluated that the charge amount (N / N charge amount described in Table 3) of the developer for evaluation left standing in an N / N environment should be +30 μC / g or more or −30 μC / g or less, and −30 μC It was evaluated that it was not good if it was more than / g + less than 30 μC / g.

  It was evaluated that the charge amount (H / H charge amount described in Table 3) of the developer for evaluation left in an H / H environment should be +10 μC / g or more or −10 μC / g or less, and −10 μC It was evaluated that it was not good if it was more than / g + less than 10 μC / g.

<Low temperature fixability>
(Preparation of evaluation machine)
As an evaluation machine, a modified multifunction machine (“TASKalfa 5550ci” manufactured by Kyocera Document Solutions Inc.) was used so that the fixing temperature could be adjusted. The evaluation developer (unused) was placed in the developing device of the evaluation machine, and the replenishment toner (unused) was placed in the toner container of the evaluation machine. In this embodiment, as the replenishment toner, the same toner as that contained in the developer for evaluation was used. In this way, an evaluation machine was prepared. The developer for evaluation was prepared by the method described in <Charge amount> above.

(Measurement of minimum fixing temperature)
The minimum fixing temperature means the lowest temperature among the fixing temperatures when it is determined that a low temperature offset has not occurred.

Specifically, the bias of the evaluator was adjusted so that the toner loading amount on the recording paper was 1.0 mg / cm ² . While conveying printing paper (90 g / m ² printing paper) at a linear speed of 200 mm / sec, an unfixed solid image was formed on the printing paper.

  The printing paper on which an unfixed solid image was formed was passed through the fixing device of the evaluation machine. At this time, by increasing the temperature of the fixing device of the evaluation machine (specifically, the temperature of the fixing roller included in the fixing device of the evaluation machine) by 5 ° C. from 100 ° C., the fixing temperature is 100 ° C. or more and 200 ° C. or less. The temperature was raised by 5 ° C. over the temperature range of In this way, solid images (21 types) fixed at each fixing temperature were obtained.

  Each of the obtained solid images was subjected to a rubbing test to determine whether or not a low temperature offset occurred. Specifically, the recording paper on which the solid image was fixed was folded in half so that the surface on which the solid image was fixed was inside. Using a 1 kg weight coated with a fabric, the recording sheet was rubbed 5 times on the fold. Thereafter, the recording paper was expanded, and the length of toner peeling (hereinafter referred to as peeling width) in the portion where the solid image was fixed in the bent portion of the recording paper was measured. When the peeling width was less than 1.0 mm, it was determined that the low temperature offset did not occur, and when the peeling width was 1.0 mm or more, it was determined that the low temperature offset occurred. In this way, the minimum fixing temperature was determined. When the minimum fixing temperature was 160 ° C. or lower, the toner was evaluated as having excellent low-temperature fixing properties. On the other hand, if the minimum fixing temperature was higher than 160 ° C., the toner was evaluated as not having excellent low-temperature fixability.

<High temperature offset resistance>
The maximum fixing temperature was determined using the evaluation machine prepared by the method described in the above <Low-temperature fixability>. Here, the maximum fixing temperature means the highest fixing temperature among the fixing temperatures when it is determined that a high temperature offset has not occurred.

  Specifically, an unfixed solid image was formed on the printing paper using an evaluation machine. The printing paper on which an unfixed solid image was formed was passed through the fixing device of the evaluation machine. At this time, by increasing the temperature of the fixing device of the evaluation machine (specifically, the temperature of the fixing roller included in the fixing device of the evaluation machine) by 5 ° C. from 180 ° C., the fixing temperature is 180 ° C. or more and 250 ° C. or less. The temperature was raised by 5 ° C. over the temperature range of In this way, a solid image fixed at each fixing temperature was obtained.

  Thereafter, whether or not a high temperature offset occurred was visually confirmed. More specifically, it was visually confirmed whether or not the toner adhered to the peripheral surface of the fixing roller. In this way, the maximum fixing temperature was determined. When the maximum fixing temperature was 200 ° C. or higher, the toner was evaluated as having excellent high-temperature offset resistance. On the other hand, if the maximum fixing temperature was less than 200 ° C., it was evaluated that the toner was not excellent in high temperature offset resistance.

[Evaluation results]
Table 2 shows physical property values of the toners T-1 to T-9. Table 3 shows the evaluation results of the toners T-1 to T-9. In Table 3, the constant α means the charge decay constant α. Further, the N / N charge amount means the charge amount of the developer for evaluation left standing in the N / N environment, and the H / H charge amount means the charge amount of the evaluation developer left still in the H / H environment. It means the amount of charge.

  Each of the toners T-1 to T-5 (the toners according to Examples 1 to 5) had the above-described basic configuration. Specifically, each of the toners T-1 to T-5 includes a plurality of toner particles. The toner particles each had a toner core, a shell layer, and a plurality of wax particles. The shell layer contained a resin and covered a part of the surface area of the toner core. When the SEM image was analyzed for each of the toners T-1 to T-5, the surface of the shell layer had a sea area and a plurality of island areas each surrounded by the sea area. . The sea region had a stronger hydrophobicity than each of the island regions. Each of the island-like regions had a higher charging property than the sea-like region. The wax particles included core added wax particles. Each of the core externally added wax particles was provided in a portion of the surface area of the toner core exposed from the shell layer. The content of the wax particles in the toner was 1 part by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the shell resin. As shown in Table 3, the toners T-1 to T-5 have sufficient chargeability in a normal temperature and normal humidity environment as well as a high temperature and high humidity environment, excellent low temperature fixability, and excellent high temperature offset resistance. .

  On the other hand, the toners T-6 to T-9 did not have the basic configuration described above. Specifically, in toner T-6 (toner according to comparative example 1), the toner particles did not include wax particles. The reason for this is considered that Toner T-6 was produced without using a dispersion of wax particles.

  As a result of image analysis of the SEM image of the toner T-7 (toner according to Comparative Example 2), a hydrophobic region was formed over the entire surface of the shell layer. The reason for this is considered that the shell layer was formed without using the suspension B.

  As a result of image analysis of the SEM image of the toner T-8 (toner according to Comparative Example 3), a region having a charging property on the surface of the shell layer was too wide to be formed into an island shape. Therefore, it is considered that the toner T-8 has a lower surface hydrophobicity of the toner particles than the toners T-1 to T-5. As a result, as shown in Table 3, it is considered that the charge amount in the high-temperature and high-humidity environment was significantly reduced in the toner T-8 as compared with the toners T-1 to T-5.

  The toner T-9 (the toner according to Comparative Example 4) had a higher wax particle content than the toners T-1 to T-5. Therefore, it is considered that the toner T-9 did not have sufficient chargeability in a normal temperature and normal humidity environment.

  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, a printer, or a multifunction machine.

10, 20, 30 Toner particle 11 Toner core 12 Shell layer 12a Resin particle 12b Resin film 13 Core added wax particle 23 Shell added wax particle 33 Shell added wax particle 131 Inner portion 133 Outer portion R1 Island-like region R2 Sea-like region

Claims (6)

An electrostatic latent image developing toner comprising a plurality of toner particles,
Each of the toner particles includes a toner core, a shell layer, and a plurality of wax particles,
The shell layer contains a resin and covers a part of the surface area of the toner core;
The surface of the shell layer has a sea region and a plurality of island regions each surrounded by the sea region,
The sea region has a stronger hydrophobicity than each of the island regions,
Each of the island regions has a higher charging property than the sea region,
The wax particles include core externally added wax particles,
The core externally added wax particles are provided in a portion of the surface area of the toner core exposed from the shell layer,
The electrostatic latent image developing toner, wherein the content of the wax particles in the electrostatic latent image developing toner is 1 part by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the resin. The wax particles further include at least one of shell-added wax particles and shell-added wax particles,
The shell layer exists between the toner core and the shell-added wax particles,
At least a part of the shell-added wax particles is embedded in the shell layer;
The electrostatic latent image developing toner according to claim 1, wherein the shell externally added wax particles are provided on a surface of the shell layer.   3. The electrostatic latent image developing toner according to claim 1, wherein a ratio of an area of the toner core covered with the shell layer in a surface area of the toner core is 40% or more and 60% or less. The shell layer has a resin film containing a first resin and a plurality of resin particles each containing a second resin;
The first resin has a stronger hydrophobicity than the second resin,
The second resin has a stronger charging property than the first resin,
The portion of the resin film exposed on the surface of the shell layer corresponds to the sea area,
4. The electrostatic latent image developing toner according to claim 1, wherein a portion of the resin particles exposed from the resin film corresponds to the island-shaped region. Each of the toner particles has a positive chargeability,
The electrostatic latent image developing toner according to claim 4, wherein the second resin includes a structural unit derived from a nitrogen-containing vinyl compound. A method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 5,
Producing the toner core;
Preparing a dispersion of the wax particles;
Preparing a first dispersion;
Preparing a second dispersion;
Forming the shell layer;
Including
The first dispersion is a dispersion of particles containing a marine region resin;
The second dispersion is a dispersion of particles containing an island-shaped region resin,
The step of forming the shell layer includes a step of mixing the toner core, the wax particle dispersion, the first dispersion, and the second dispersion at a predetermined temperature. A method for producing a developing toner.

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