JP6601435B2 - Toner for developing electrostatic latent image and method for producing the same - Google Patents

Description

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

  As toner particles contained in the electrostatic latent image developing toner, toner particles having a toner core and a shell layer formed on the surface of the toner core are known (see Patent Document 1). For example, Patent Document 1 describes that the toner core contains a crystalline polyester resin.

JP 2010-61036 A

  If the binder resin of the toner particles contains a crystalline polyester resin, a toner having excellent low-temperature fixability and heat-resistant storage stability can be provided. Here, when comparing the crystalline polyester resin and the amorphous polyester resin, the amorphous polyester resin contains many aromatic rings in the molecule, whereas the crystalline polyester resin has a linear type in the molecule. Contains a lot of hydrocarbon chains. For this reason, the crystalline polyester resin is less likely to retain a charge than the amorphous polyester resin. Therefore, if the binder resin contains a crystalline polyester resin, the charge amount of the toner tends to decrease. When the charge amount of the toner is reduced, the reversely charged toner is likely to be scattered, so that fog is likely to occur. In particular, since the molecular motion becomes active at high temperatures, it becomes even more difficult to hold charges by the crystalline polyester resin. Thereby, the occurrence of fog becomes prominent.

  The present invention has been made in view of the above circumstances, and an object thereof is an electrostatic latent image developing toner that is excellent in low-temperature fixability and heat-resistant storage stability and can prevent a decrease in charge amount, and a method for producing the same. Is to provide.

The electrostatic latent image developing toner according to the present invention has a positive charging property and includes a plurality of toner particles. Each of the toner particles includes toner base particles. Each of the toner base particles has a toner core, a plurality of first particles containing silica, and a shell layer. Each of the toner cores contains a crystalline polyester resin and an amorphous polyester resin. Each of the first particles includes an embedded portion embedded in the surface of the toner core and a protruding portion that protrudes outward in the radial direction of the toner particle from the surface of the toner core. The ratio of the area of the toner core covered with the first particles in the surface area of the toner core is 50% or more. The number average primary particle diameter R _{f of} the first particles is 200 nm or more and 500 nm or less. The shell layer covers a portion of the surface of the toner core that is exposed from the first particles and a surface of the protruding portion. The shell layer contains a resin having positive chargeability stronger than that of the amorphous polyester resin. A thickness T of the shell layer is 20 nm or more and 50 nm or less.

  The method for producing a toner for developing an electrostatic latent image according to the present invention is a method for producing a toner 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 embedding a part of each of the first particles in the surface of the toner core, and the shell layer. Forming a portion of the surface of the toner core that is exposed from the first particles and a surface of the protruding portion.

  The toner for developing an electrostatic latent image according to the present invention is excellent in low-temperature fixability and heat-resistant storage stability, and can prevent a decrease in charge amount.

FIG. 3 is a cross-sectional view illustrating a configuration of toner particles according to an embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view illustrating a configuration of toner particles according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a configuration of toner particles according to an embodiment of the present invention.

  An embodiment of the present invention will be described. In the following, evaluation results (values indicating shape or physical properties) of toner particles, toner base particles, toner cores, first particles, or external additive particles are measured for a considerable number of particles unless otherwise specified. The number average of the values obtained.

Moreover, the number average primary particle diameter of the powder is the number of equivalent circle diameters of primary particles (the diameter of a circle having the same area as the projected area of the particles) measured using a microscope unless otherwise specified. Average value. Unless otherwise specified, the measured volume median diameter (D ₅₀ ) of the powder is based on the Coulter principle (pore electrical resistance method) using “Coulter Counter Multisizer 3” manufactured by Beckman Coulter, Inc. Based on the measured value.

  Moreover, each measured value of an acid value and a hydroxyl value is a value measured according to "JIS (Japanese Industrial Standard) K0070-1992" unless otherwise specified. Each measured value of the number average molecular weight (Mn) and the mass average molecular weight (Mw) is a value measured using gel permeation chromatography unless otherwise specified. 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. The softening point (Tm) is a value measured using a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation) unless otherwise specified.

Further, the crystallinity index of the crystalline polyester resin is a value obtained by using the following formula unless otherwise specified. Here, in the following formula, “softening point” means the softening point (Tm) of the crystalline polyester resin. The “endothermic curve” means an endothermic curve measured using a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.). The “maximum peak temperature in the endothermic curve” means the peak temperature of the endothermic peak located on the highest temperature side among the endothermic peaks appearing in the endothermic curve. In the crystalline polyester resin, the maximum peak temperature in the endothermic curve corresponds to the melting point (Mp).
(Crystallinity index of crystalline polyester resin) = (softening point) / (maximum peak temperature in endothermic curve)

  The chargeability means chargeability in frictional charging unless otherwise specified. The strength of positive charging in frictional charging or the strength of negative charging in frictional charging can be confirmed by a known charge train or the like.

  In addition, “system” may be added after the compound name to generically refer to the compound and its derivatives. When a polymer name is represented 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”.

[Configuration of electrostatic latent image developing toner according to the embodiment]
The electrostatic latent image developing toner according to the exemplary embodiment (hereinafter sometimes referred to as “toner”) has a positive charging property and includes a plurality of toner particles. Each toner particle includes toner base particles. The toner base particles each have a toner core, a plurality of first particles containing silica, and a shell layer. Each toner core contains a crystalline polyester resin and an amorphous polyester resin. Each of the first particles includes an embedded portion embedded in the surface of the toner core and a protruding portion protruding outward in the radial direction of the toner particle from the surface of the toner core. The ratio of the area of the toner core covered with the first particles in the surface area of the toner core (hereinafter referred to as “the coverage of the first particles”) is 50% or more. The number average primary particle diameter R _{f of} the first particles is 200 nm or more and 500 nm or less. The shell layer covers a portion of the surface of the toner core that is exposed from the first particles (hereinafter referred to as “exposed portion of the toner core”) and a surface of the protruding portion. The shell layer contains a resin having positive chargeability stronger than that of the amorphous polyester resin (hereinafter simply referred to as “resin having positive charge”). The thickness T of the shell layer is 20 nm or more and 50 nm or less.

<Explanation of terms>
The number average primary particle diameter R _f of the first particles is a circle equivalent diameter of the primary particles (diameter of a circle having the same area as the projected area of the particles) r _f (see FIG. 2 described later). ) Number average value.

The thickness T of the shell layer means the size of the shell layer in the radial direction of the toner particles, and is 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 toner base particles is analyzed using image analysis software (for example, “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 shell layer (corresponding to the surface of the toner core) to the surface of the shell layer is measured. The average value of the four lengths thus measured is defined as the thickness t (see FIG. 2 described later) of the shell layer provided in one toner base particle. Such a measurement of the thickness t of the shell layer is performed on the plurality of toner base particles, and an average value of the thickness t of the shell layers included in the plurality of toner base particles is obtained. The average value of the thickness t of the shell layer thus obtained is defined as “shell layer thickness T”.

The coverage of the first particles is measured by the following method.
Specifically, first, a TEM photograph of toner base particles is taken. Next, the TEM photograph of the toner mother particles is binarized using image analysis software (for example, “WinROOF” manufactured by Mitani Corporation). At this time, the binarization process is performed on the TEM photograph of the toner base particles so that the region where the first particles are provided and the region where the first particles are not provided in the surface region of the toner core are clear. . And the ratio of the 1st particle which occupies for the whole surface surface is calculated using the projection area of a 1st particle | grain. This operation is performed on a plurality of TEM photographs (TEM photographs of toner mother particles), and an average value of the occupation ratio of the first particles is calculated. The average value of the occupation ratio of the first particles obtained in this way is defined as “first particle coverage”.

The number average value H of the length of the protruding portion of the first particle in the radial direction of the toner particle (hereinafter referred to as “the protruding height of the first particle”) is measured by the following method.
First, a cross-sectional TEM photograph of the toner base particles is taken. Next, a cross-sectional TEM photograph of the toner base particles is analyzed using image analysis software (for example, “WinROOF” manufactured by Mitani Corporation). Specifically, in the image analysis software, manual measurement line length measurement of the measurement tool is selected. With the manual measurement line length measurement selected, several first particles (first particles embedded on the surface of the toner core) are randomly selected in the cross-sectional TEM photograph of the toner base particles. Then, in each of the selected first particles, the length h (see FIG. 2 described later) of the protruding portion of the first particle in the radial direction of the toner particle is measured, and the number average value thereof is calculated. The number average value of the length h thus determined is defined as “number average value H of protrusion heights of the first particles”.

<Configuration of electrostatic latent image developing toner according to first example>
Hereinafter, the configuration of the toner according to the exemplary embodiment will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view illustrating a configuration of toner particles contained in a toner according to a first specific example. FIG. 2 is an enlarged cross-sectional view illustrating the configuration of the toner particles shown in FIG. In FIG. 2, the surface of the toner core 21 is indicated by a straight line. However, in actual toner particles, the surface of the toner core has a spherical shape (circular shape in cross section). In FIG. 2, a part of the surface of the shell layer 25 is indicated by a straight line. However, in actual toner particles, the surface of the shell layer 25 has a curved shape. In FIG. 2, the radial direction of the toner particle 10 (see FIG. 1) is represented by “Dr”, the radially inner side of the toner particle 10 is represented by “X1”, and the radially outer side of the toner particle 10 is represented by “X2”. To express.

The toner according to the first specific example is positively charged and includes a plurality of toner particles 10. Each of the toner particles 10 includes toner base particles 20. The toner base particles 20 each have a toner core 21, a plurality of first particles 23 containing silica, and a shell layer 25. The toner cores 21 each contain a crystalline polyester resin and an amorphous polyester resin. Each of the first particles 23 includes an embedded portion 231 embedded in the surface of the toner core 21 and a protruding portion 233 that protrudes outward in the radial direction X2 of the toner particle 10 from the surface of the toner core 21. The coverage of the first particles 23 is 50% or more. The number average primary particle diameter R _{f of} the first particles 23 is 200 nm or more and 500 nm or less. The shell layer 25 covers the exposed portion of the toner core 21 and the surface of the protruding portion 233 of the first particle 23. The shell layer 25 contains a resin having positive chargeability. The thickness T of the shell layer 25 is 20 nm or more and 50 nm or less. Thereby, in the first specific example, it is possible to provide a toner excellent in low-temperature fixability and heat-resistant storage stability. Further, in the first specific example, it is possible to prevent a decrease in the charge amount of the toner.

  Specifically, the toner core 21 contains a crystalline polyester resin. As a result, it is possible to provide a toner having excellent low-temperature fixability and heat-resistant storage stability.

  The shell layer 25 covers the exposed portion of the toner core 21 and the surface of the protruding portion 233 of the first particle 23. In general, the shell layer is superior in heat resistance compared to the toner core. Therefore, when the thickness T of the shell layer 25 is 20 nm or more, a toner having excellent heat-resistant storage stability can be provided. Further, when the thickness T of the shell layer 25 is 50 nm or less, a toner having excellent low-temperature fixability can be provided.

  Since the shell layer 25 covers the exposed portion of the toner core 21 and the surface of the protruding portion 233 of the first particle 23, the surface of the toner base particle 20 is constituted by the shell layer 25. Here, the shell layer 25 contains a resin having positive chargeability. Therefore, the toner according to the first specific example is easily positively charged by friction with the electrostatic latent image developing carrier (hereinafter referred to as “carrier”) or magnetic powder. More specifically, when the shell layer 25 and the carrier or the magnetic powder are rubbed together, a positive charge is easily generated in the shell layer 25.

  Since the shell layer 25 covers the surface of the protruding portion 233 of the first particle 23, the first particle 23 exists on the radially inner side X <b> 1 of the toner particle 10 than the shell layer 25. In general, silica particles have a higher electric resistance than a resin (for example, a resin or a binder resin constituting a shell layer). The first particles 23 contain silica. For these reasons, the first particles 23 have a higher electrical resistance than the toner core 21 and the shell layer 25, and thus can easily retain electric charges. Further, since the coverage of the first particles 23 is 50% or more, the amount of the first particles 23 existing on the radially inner side X1 of the toner particles 10 from the shell layer 25 can be secured. As described above, the positive charges generated in the shell layer 25 can be held by the first particles 23. Therefore, it is possible to prevent the toner charge amount from decreasing. Therefore, scattering of the reversely charged toner can be prevented, and consequently, the occurrence of fogging can be prevented.

  The toner according to the first specific example will be further described. The first particle 23 includes an embedded portion 231. The protruding portion 233 of the first particle 23 is covered with the shell layer 25. Accordingly, it is possible to prevent the first particles 23 from being detached from the surface of the toner core 21 during image formation. Therefore, it is possible to prevent the toner charge amount from being reduced during image formation. Therefore, even when continuous printing is performed, scattering of the reversely charged toner can be prevented, and as a result, occurrence of fogging can be prevented.

The number average primary particle diameter R _f of the first particles 23 is 200 nm or more and 500 nm or less. Thus, the 1st particle 23 is a large diameter silica particle. Therefore, even when the toner according to the first specific example is subjected to mechanical or thermal stress in the image forming apparatus, the entire first particle 23 can be prevented from being completely embedded in the toner core 21. This can also prevent the toner charge amount from decreasing during image formation. Therefore, even when continuous printing is performed, scattering of the reversely charged toner can be prevented, and as a result, occurrence of fogging can be prevented.

  As an example of “when the toner according to the first specific example is subjected to mechanical stress in the image forming apparatus”, the following cases can be considered. Specifically, in the image forming apparatus, the toner particles 10 and the members constituting the image forming apparatus, the carrier particles constituting the carrier, or other toner particles 10 collide with each other. Thereby, an external force is easily applied to the toner particles 10.

  In addition, as an example of “when the toner according to the first specific example is subjected to thermal stress in the image forming apparatus”, the following cases can be considered. Specifically, the internal temperature of the image forming apparatus rises due to the generation of frictional heat in the image forming apparatus. As a result, the temperature of the toner contained in the image forming apparatus increases. Therefore, the toner core 21 is easily softened.

Hereinafter, a preferable configuration of the toner according to the first specific example will be described. Preferably, the number average value H of the protrusion heights of the first particles 23 is not less than 0.4 times and not more than 0.8 times the number average primary particle diameter R _f of the first particles 23. Thereby, it is possible to further prevent the first particles 23 from being detached from the surface of the toner core 21 during image formation. Further, it is possible to further prevent the entire first particles 23 from being completely embedded in the toner core 21 during image formation. For these reasons, even when continuous printing is performed, scattering of the reversely charged toner can be prevented, and as a result, occurrence of fogging can be prevented.

  Preferably, the first particles 23 are silica particles whose surfaces are not subjected to a hydrophobic treatment and a positive charging treatment. Thereby, it is possible to prevent the first particles 23 from being deteriorated due to the hydrophobic treatment and the positive charging treatment (particularly the positive charging treatment) applied to the surface. Therefore, a toner having excellent charging characteristics can be provided. In the toner particles 10, positive charges generated in the shell layer 25 can be held by the first particles 23. Therefore, silica particles whose surfaces are not positively charged can be used as the first particles 23. In the first particle 23, the buried portion 231 is buried in the toner core 21, and the surface of the protruding portion 233 is covered with the shell layer 25. Therefore, silica particles whose surfaces are not hydrophobized can be used as the first particles 23.

<Configuration of electrostatic latent image developing toner according to second example>
Hereinafter, a preferred configuration of the toner according to the exemplary embodiment will be described in detail with reference to FIG. FIG. 3 is a cross-sectional view illustrating the configuration of toner particles contained in the toner according to the second specific example. Hereinafter, differences from the toner according to the first specific example will be mainly described.

The toner particles 50 shown in FIG. 3 include an external additive that adheres to the surface of the shell layer 25. The external additive includes a plurality of external additive particles 52. The number average primary particle diameter R _s of the external additive particles 52 is preferably 10 nm or more and 40 nm or less. Thereby, the fluidity | liquidity of the toner particle 50 can be improved. Here, the number average primary particle diameter R _s of the external additive particles 52 is an equivalent circle diameter of a primary particle (diameter of a circle having the same area as the projected area of the particle) r _s measured using a microscope. Means the number average value.

The external additive particles 52 preferably include particles formed by subjecting the surface of silica particles to a hydrophobic treatment and a positive charging treatment. When the surface of the silica particles is subjected to a hydrophobic treatment, OH is substituted with a functional group that is less reactive than OH in at least one of the silanol groups present on the surface of the silica particles. Examples of the functional group having a lower reactivity than OH include an alkyl group. Further, when the surface of the silica particles is positively charged, OH is substituted with a functional group having a higher positive charge than OH in at least one silanol group present on the surface of the silica particles. Examples of functional groups having a stronger positive charge than OH include amino groups (—NH ₂ groups). The configuration of the toner according to the present embodiment and the preferable configuration of the toner according to the present embodiment have been described above with reference to FIGS. Note that the toner according to the present embodiment may be toner contained in a one-component developer, or may constitute a two-component developer together with a carrier.

[Method for Producing Toner According to this Embodiment]
The toner production method according to the present embodiment includes a toner mother particle production process, and preferably further includes an external addition process. By performing the toner mother particle manufacturing process, a toner including a plurality of toner particles shown in FIG. 1 can be manufactured. By sequentially performing the toner mother particle manufacturing step and the external addition step, a toner including a plurality of toner particles shown in FIG. 3 can be manufactured. The toner particles produced at the same time are considered to have substantially the same configuration.

<Manufacturing process of toner base particles>
The toner mother particle manufacturing process includes a toner core manufacturing process, a first particle embedding process, and a shell layer forming process.

(Manufacturing process of toner core)
In the production process of the toner core, the toner core is preferably produced by a known aggregation method or a known pulverization method. Thereby, the toner core can be easily manufactured.

More preferably, the toner core is produced by a known pulverization method. Thereby, a toner having a dielectric loss tangent (tan δ) of 1.5 × 10 ⁻³ or less can be manufactured. Generally, the smaller the dielectric loss tangent of the toner, the easier it is for the toner to retain a charge. Therefore, if a toner having a dielectric loss tangent of 1.5 × 10 ⁻³ or less can be manufactured, a toner having excellent charge retention performance can be manufactured. Therefore, if the toner core is produced by a known pulverization method, it is possible to provide a toner that can further retain the positive charge generated in the shell layer. Therefore, it is possible to provide a toner that can further prevent a decrease in charge amount.

Here, the dielectric loss tangent of the toner can be measured by the following method. Specifically, first, a toner is compression molded to produce a sample having a predetermined shape. Next, the sample is set between a pair of solid electrodes. Subsequently, using an LCR meter, a phase shift is measured when an AC voltage of 5 × 10 ³ Hz is applied between the solid electrodes. The phase shift measured in this way is referred to as “dielectric loss tangent of toner”.

(Implantation process of the first particles)
In the step of burying the first particles, the toner core and the first powder are mixed using a mixer (for example, an FM mixer manufactured by Nippon Coke Kogyo Co., Ltd.). Here, the first powder means a powder composed of a plurality of first particles. When the toner core and the first powder are mixed, a part of each of the first particles is embedded in the surface of the toner core. In this way, particles (hereinafter referred to as “composite toner core”) in which a part of each first particle is embedded in the surface of the toner core are obtained.

  The first particles are preferably silica particles whose surfaces have not been subjected to a hydrophobic treatment and a positive charging treatment. For example, silica particles produced by a known sol-gel method can be used as the first particles.

  By adjusting the mixing condition of the toner core and the first powder, the number average value H of the protrusion height of the first particles and the coverage of the first particles can be adjusted. For example, if the mixing time of the toner core and the first powder is long, the first particles are easily embedded in the surface of the toner core. Therefore, the number average value H of the protrusion heights of the first particles tends to be small. Moreover, it exists in the tendency for the coverage of a 1st particle to become high. When the rotation speed of the stirrer included in the mixer is fast, the same tendency is easily exhibited. On the other hand, if the mixing time of the toner core and the first powder is short, the first particles are difficult to be embedded in the surface of the toner core. For this reason, the number average value H of the protrusion heights of the first particles tends to increase. Moreover, it exists in the tendency for the coverage of a 1st particle to become low. When the rotation speed of the stirrer included in the mixer is low, the same tendency is easily exhibited.

  Moreover, if the compounding quantity of 1st powder is adjusted, the coverage of 1st particle | grains can be adjusted. For example, if the amount of the first powder is large, the coverage of the first particles tends to be high. On the other hand, if the amount of the first powder is small, the coverage of the first particles tends to be low.

(Shell layer formation process)
In the shell layer forming step, the surface of the composite toner core is covered with the shell layer by, for example, an in-situ polymerization method, a liquid-cured coating method, or a coacervation method. Thereby, the shell layer is formed on the exposed portion of the toner core and the surface of the protruding portion of the first particle. In this way, a plurality of toner base particles are obtained. More specifically, a toner including a plurality of toner particles shown in FIG. 1 is obtained.

  The thickness T of the shell layer can be adjusted by adjusting the amount of resin constituting the shell layer (hereinafter sometimes referred to as “shell resin”). For example, if the amount of the shell resin is large, the thickness T of the shell layer tends to increase. On the other hand, if the amount of the shell resin is small, the thickness T of the shell layer tends to be small.

<External addition 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 plurality of toner particles are obtained. More specifically, a toner including a plurality of toner particles shown in FIG. 3 is obtained.

  The external additive particles are preferably produced by the following method. Specifically, first, silica particles are produced by a known sol-gel method. Next, the surface of the manufactured silica particles is subjected to a hydrophobic treatment and a positive charging treatment. In the hydrophobic treatment, it is preferable to treat the surface of the silica particles using a known hydrophobic treatment agent. In the positive charging treatment, it is preferable to treat the surface of the silica particles with a known positive charge imparting agent.

[Examples of materials and physical properties constituting toner]
The toner includes a plurality of toner particles. Each toner particle includes toner base particles. The toner base particles have a toner core, first particles, and a shell layer. The first particles are as described in the above [Configuration of electrostatic latent image developing toner according to this embodiment]. Hereinafter, the toner core and the shell layer 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 release agent, and a charge control 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.

  As described above, the toner core contains a crystalline polyester resin and an amorphous polyester resin. Below, after explaining a polyester resin, a crystalline polyester resin and an amorphous polyester resin are demonstrated in order.

(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 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 more than 5% by mass and 30% by mass or less with respect to the total amount of the polyester resin contained in the toner core (total amount of the crystalline polyester resin and the amorphous polyester resin) It is preferably 10% by mass or more and 30% 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 more than 5 g and 30 g or less (more preferably 10 g or more and 30 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.

(Binder resin: other resins)
By using a combination of a plurality of resins as the binder resin, the properties of the binder resin (specifically, hydroxyl value, acid value, glass transition point, or softening point) can be adjusted. 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. In order for the binder resin to have a strong anionic property, it is preferable that at least one of the acid value and the hydroxyl value of the binder resin is 10 mgKOH / g or more.

  The toner core preferably contains a thermoplastic resin. As the thermoplastic resin, in addition to the crystalline polyester resin and the amorphous polyester resin, for example, a styrene resin, an acrylic acid resin, an olefin resin, a vinyl resin, a polyamide resin, or a 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.

(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 1.00 parts by mass or more and 20.0 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 offset resistance of the toner. In order to increase the anionicity of the toner core, it is preferable to produce the toner core using an anionic wax. In order to improve the fixing property or offset resistance of the toner, the amount of the release agent is preferably 1.00 parts by mass or more and 30.0 parts by mass or less with respect to 100 parts by mass of the binder resin.

  Examples of the releasing agent include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, or Fischer-Tropsch wax; oxidized polyethylene wax or a block thereof Oxides of aliphatic hydrocarbon waxes such as copolymers; plant waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, or rice wax; animal properties such as beeswax, lanolin, or whale wax Waxes; mineral waxes such as ozokerite, ceresin, or petrolatum; waxes based on fatty acid esters such as montanate ester wax or castor wax; fats such as deoxidized carnauba wax The wax portion of the ester or the whole was deoxygenated be used. 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 contains a resin having positive chargeability, and is preferably composed of a resin having positive chargeability. The positively chargeable resin is preferably at least one of a styrene-acrylic acid resin and an amorphous polyester resin, and more preferably a styrene-acrylic acid resin. The amorphous polyester resin is as described above (binder resin: amorphous polyester resin). Hereinafter, the styrene-acrylic acid resin will be described.

  The styrene-acrylic acid resin is a copolymer of one or more styrene monomers and one or more acrylic monomers. As the styrene monomer used for synthesizing the styrene-acrylic acid resin, the following styrene monomers can be suitably used. Moreover, the acrylic acid monomer shown below can be suitably used as the acrylic acid monomer used for synthesizing the styrene-acrylic acid resin.

  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.

  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.

  Examples of the present invention will be described. Table 1 shows toners T-1 to T-11 according to examples or comparative examples. In Table 1, “particle diameter” means the number average primary particle diameter of the first particles. “Height” means the average number of protrusion heights of the first particles. “Ratio” means a numerical value obtained by dividing “height” by “particle diameter” (ratio = height / particle diameter). “Coverage” means the coverage of the first particles. “Resin X1” means a styrene-acrylic acid resin.

  Below, the measurement method of the physical-property value of 1st particle | grains AE and the preparation method of the dispersion liquid Q are demonstrated first. Next, a production method of toners T-1 to T-11, a measurement method of physical property values, an evaluation method, and an evaluation result will be described.

[Method for Measuring Number Average Primary Particle Diameter of First Particles A to E]
As the first particles A, silica particles (“Seahoster (registered trademark) KE-P30” manufactured by Nippon Shokubai Co., Ltd.) were prepared. As the first particles B, silica particles (“Chihoster KE-P20” manufactured by Nippon Shokubai Co., Ltd.) were prepared. As the first particles C, silica particles (“Seahoster KE-P50” manufactured by Nippon Shokubai Co., Ltd.) were prepared. As the first particles D, silica particles (“Seahoster KE-P10” manufactured by Nippon Shokubai Co., Ltd.) were prepared. As the first particles E, silica particles (“Seahoster KE-P70” manufactured by Nippon Shokubai Co., Ltd.) were prepared.

  SEM photographs of the first particles (each of the first particles A to E) were taken using a scanning electron microscope. Images of 50 first particles were randomly extracted from SEM photographs. Using the extracted image of the first particle, the length of the first particle in the major axis direction was determined. The total obtained length was divided by the number of first particles (specifically 50). The obtained value was defined as the number average primary particle size of the first particles.

  Each of the first particles A to E had a sharp particle size distribution. More specifically, the first particles A to E substantially contained only the first particles having particle sizes of about 300 nm, about 200 nm, about 500 nm, about 100 nm, and about 700 nm, respectively.

[Method for Preparing Dispersion Q]
First, in a flask (capacity: 2 L) equipped with a stirrer, a condenser, a thermometer, and a nitrogen introduction tube, 250 parts by mass of isobutanol (solvent), 45 parts by mass of diethylaminoethyl methacrylate, and 45 parts by mass of paratoluene sulfone. Methyl acid was added. The temperature of the flask was raised to 80 ° C. While maintaining the temperature of the flask at 80 ° C., the contents of the flask were stirred for 1 hour under a nitrogen atmosphere. While maintaining this state, the quaternization reaction was allowed to proceed.

  Next, while introducing nitrogen into the flask, 156 parts by mass of styrene, 72 parts by mass of butyl acrylate, and 12 parts by mass of t-butylperoxy 2-ethylhexanoate (manufactured by Arkema Yoshitomi Corp. Oxide-based reaction initiator). The temperature of the flask was raised to 95 ° C. (polymerization temperature). While maintaining the temperature of the flask at 95 ° C., the contents of the flask were stirred for 3 hours. 12 parts by mass of t-butylperoxy 2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd.) was further added to the flask, and the contents of the flask were stirred for 3 hours. The contents of the flask were dried under a high temperature and reduced pressure environment (temperature of 140 ° C. and pressure of 10 kPa) to remove the solvent component from the contents of the flask. The obtained solid was pulverized to obtain a coarsely pulverized product. The coarsely pulverized product was finely pulverized to obtain a finely pulverized product (particle size: 10 μm or less).

  100 parts by mass of finely pulverized product, 1 part by mass of a cationic surfactant (“Coatamine (registered trademark) 24P” manufactured by Kao Corporation), and 25 parts by mass of an aqueous sodium hydroxide solution (concentration: 0.1 N) Mix and further add ion exchange water. In this way, 400 parts by mass of slurry was obtained. The obtained slurry was put in a pressure-resistant stainless steel container (round bottom), and the pressure-resistant stainless steel container was put in a high-speed shear emulsification apparatus (“CLEAMIX (registered trademark) CLM-2.2S” manufactured by M Technique Co., Ltd.). Using a high-speed shearing emulsifier, the contents of the pressure-resistant stainless steel container were sheared and dispersed for 30 minutes under a high-temperature and high-pressure environment (temperature 140 ° C. and pressure 0.5 MPa) (rotor rotation speed: 20000 rpm). The temperature of the pressure resistant stainless steel container was lowered to 50 ° C. at a cooling rate of 5 ° C./min while changing the rotation speed of the rotor to 15000 rpm and stirring the contents of the pressure resistant stainless steel container. In this way, a first dispersion was obtained.

The first dispersion was placed in a flask (volume: 2 L). To this flask, 100.0 parts by mass of the second dispersion was dropped over 30 minutes. The second dispersion was composed of 25.0 parts by weight of methyl methacrylate, 25.0 parts by weight of butyl acrylate, 0.2 parts by weight of octyl thioglycolate, and 1.0 part by weight of a cationic surfactant (Kao Co., Ltd. “Cotamine 24P”) and ion-exchanged water (adjusted amount). Thereafter, the temperature of the flask was raised to 95 ° C. While the temperature of the flask was maintained at 95 ° C., the contents of the flask were stirred for 2 hours. The temperature of the flask was cooled to 25 ° C. to obtain dispersion Q. In dispersion Q, resin particles were dispersed. The concentration (solid content concentration) of the resin particles in dispersion Q was 29.1% by mass. The volume median diameter (D ₅₀ ) of the resin particles was 0.09 μm.

[Toner Production Method]
<Method for Producing Toner T-1>
First, toner mother particle manufacturing steps were performed. Next, an external addition process was performed.

(1. Manufacturing process of toner base particles)
(1-1. Manufacturing process of toner core)
In an FM mixer ("FM-20B" manufactured by Nippon Coke Industries, Ltd.), 2880 parts by mass of an amorphous polyester resin (number average molecular weight Mn: 1882, mass average molecular weight Mw: 4324, acid value: 25.2 mgKOH / g, Softening point Tm: 82.1 ° C., glass transition point Tg: 55.3 ° C., and 720 parts by mass of crystalline polyester resin (number average molecular weight Mn: 1311, mass average molecular weight Mw: 34012, acid value: 3.6 mgKOH) / G, hydroxyl value: 17.9 mg KOH / g, softening point Tm: 85.6 ° C., melting point Mp: 76.4 ° C., crystallinity index: 1.12), and 184 parts by mass of wax (synthetic ester type wax, Softening point Tm: 76 ° C., acid value: 0.1 mg KOH / g) and 216 parts by mass of cyan pigment P.I. B. 15-3 (master batch, amorphous polyester resin: cyan pigment = 1: 1 (mass ratio)). The contents of the FM mixer were mixed for 180 seconds at a rotational speed of 2400 rpm.

Using the twin screw extruder ("PCM-30" manufactured by Ikegai Co., Ltd.), the obtained mixture was subjected to the conditions of a material supply speed of 5 kg / hour, a shaft rotation speed of 150 rpm, and a set temperature range (cylinder temperature range) of 150 ° C. And kneaded. The obtained melt-kneaded product was cooled. The cooled melt-kneaded product was coarsely pulverized using an FM mixer (“FM-20B” manufactured by Nippon Coke Industries, Ltd.). The coarsely pulverized product was finely pulverized using a pulverizer (“Turbo Mill RS type” manufactured by Freund Turbo Inc.). The finely pulverized product was classified using a classifier (“Elbow Jet EJ-LABO type” manufactured by Nippon Steel Mining Co., Ltd.). In this way, a toner core having a volume median diameter (D ₅₀ ) of 6.65 μm was obtained.

(1-2. First particle burying step)
1000 parts by mass of the toner core and 300 parts by mass of the first particles A were placed in an FM mixer (“FM-10B” manufactured by Nippon Coke Kogyo Co., Ltd.). While circulating hot water (40 ° C.) in the jacket of the FM mixer, the contents of the FM mixer were mixed at a rotational speed of 2800 rpm for 10 minutes. The obtained powder was sieved using a sieve of 200 mesh (aperture 75 μm). In this way, a composite toner core was obtained.

(1-3. Shell layer forming step)
In a round bottom flask (volume: 2 L, material: stainless steel) equipped with a stirrer, an aqueous solution (concentration: 25% by mass) of 50 parts by mass of an anionic surfactant (“Emar (registered trademark) 0” manufactured by Kao Corporation) and After adding 500 parts by weight of distilled water, 500 parts by weight of the composite toner core was added. While maintaining the temperature of the round bottom flask at 25 ° C., the contents of the round bottom flask were stirred at a rotation speed of 100 rpm for 10 minutes. 2 parts by mass of hydrochloric acid aqueous solution (concentration: 2N) was added to the round bottom flask to adjust the pH of the contents of the round bottom flask to 4.5.

  After adding 80 parts by mass of dispersion Q to the round bottom flask, the contents of the round bottom flask were stirred at a rotational speed of 100 rpm for 15 minutes. A sodium hydroxide aqueous solution (concentration: 1N) was added to the round bottom flask to adjust the pH of the contents of the round bottom flask to 7.0. The round bottom flask was heated at a heating rate of 0.2 ° C./min until the temperature of the round bottom flask reached 55 ° C. Thereafter, the temperature of the round bottom flask was raised to 60 ° C. While maintaining the temperature of the round bottom flask at 60 ° C., the contents of the round bottom flask were stirred at a rotational speed of 100 rpm for 2 hours. While the temperature of the round bottom flask was maintained at 60 ° C., the resin particles dispersed in the dispersion liquid Q were adhered to the surface of the composite toner core, and film formation on the surface of the composite toner core was advanced. Thereafter, heating of the round bottom flask was stopped. Then, the round bottom flask was cooled at a cooling rate of 10 ° C./min until the temperature of the round bottom flask reached 25 ° C.

(1-4. Cleaning step)
The contents of the round bottom flask were suction filtered using a Buchner funnel. The obtained wet cake-like toner base particles were dispersed again in ion-exchanged water. The resulting dispersion was suction filtered using a Buchner funnel. Such a solid-liquid separation process was repeated 5 times.

(1-5. Drying step)
The wet cake-like toner base particles that had undergone the washing step were dried at 35 ° C. for 48 hours. In this way, toner base particles were obtained. The obtained toner base particles had a volume median diameter (D ₅₀ ) of 5.53 μm and an average circularity of 0.959.

(2. External addition process)
In an FM mixer (“FM-10B” manufactured by Nippon Coke Industries Co., Ltd.), 1000 parts by mass of toner base particles and 15 parts by mass of external additive particles (“AEROSIL® REA90” manufactured by Nippon Aerosil Co., Ltd.) : Dry silica particles to which positive chargeability was imparted by surface treatment, number average primary particle diameter: about 20 nm). While circulating warm water (30 ° C.) in the jacket of the FM mixer, the contents of the FM mixer were mixed for 10 minutes at a rotational speed of 2400 rpm. The obtained powder was sieved using a sieve of 200 mesh (aperture 75 μm). Thus, a toner (toner T-1) containing a large number of toner particles was obtained.

<Method for Producing Toner T-2>
In the above (1-2. First particle embedding step), 1000 parts by mass of the toner core and 200 parts by mass of the first particles B were placed in an FM mixer. Except for this point, toner T-2 was produced according to the production method of toner T-1.

<Method for Producing Toner T-3>
In the above (1-2. First particle burying step), 1000 parts by mass of the toner core and 500 parts by mass of the first particles C were placed in an FM mixer. Except for this point, toner T-3 was produced according to the production method of toner T-1.

<Method for Producing Toner T-4>
The blending amount of the first particles A in the above (1-2. Step of burying the first particles) was 200 parts by mass. Except for this point, toner T-4 was produced according to the production method of toner T-1.

<Method for Producing Toner T-5>
The blending amount of the dispersion Q in the above (1-3. Shell layer forming step) was 120 parts by mass. Except for this point, toner T-5 was produced according to the production method of toner T-1.

<Method for Producing Toner T-6>
In the above (1-2. First particle burying step), 1000 parts by mass of the toner core and 100 parts by mass of the first particles D were placed in an FM mixer. Except for this point, toner T-6 was produced according to the production method of toner T-1.

<Method for Producing Toner T-7>
In the above (1-2. First particle burying step), 1000 parts by mass of the toner core and 700 parts by mass of the first particles E were put in an FM mixer. Except for this point, toner T-7 was produced according to the production method of toner T-1.

<Method for Producing Toner T-8>
The blending amount of the first particles A in the above (1-2. Step of burying the first particles) was 150 parts by mass. Except for this point, toner T-8 was produced according to the production method of toner T-1.

<Method for Producing Toner T-9>
The blending amount of the dispersion Q in the above (1-3. Shell layer forming step) was 40 parts by mass. Except for this point, toner T-9 was produced according to the production method of toner T-1.

<Method for Producing Toner T-10>
The above (1-3. Shell layer forming step), (1-4. Washing step), and (1-5. Drying step) were not performed. Except for this point, toner T-10 was produced according to the production method of toner T-1.

<Method for Producing Toner T-11>
The blending amount of the dispersion Q in the above (1-3. Shell layer forming step) was 140 parts by mass. Except for this point, Toner T-11 was manufactured according to the manufacturing method of Toner T-1.

[Measurement method of physical properties of toner]
The number average value of the protrusion height of the first particles, the coverage of the first particles, and the thickness of the shell layer were measured by the following method. When measuring these physical property values, toner particles from which the external additive was removed (that is, toner base particles) were used as samples.

<Method for measuring number average value of protrusion height of first particles>
First, a cross-sectional TEM photograph of toner base particles (toner base particles contained in each of toners T-1 to T-11) was taken. Next, a cross-sectional TEM photograph of the toner base particles was analyzed using image analysis software (“WinROOF” manufactured by Mitani Corporation). Specifically, in the image analysis software, manual measurement line length measurement of the measurement tool was selected. With the line length measurement of manual measurement selected, several first particles (each of the first particles A to E) were randomly selected in the cross-sectional TEM photograph of the toner base particles. Then, in each of the selected first particles, the length of the protruding portion in the radial direction of the toner particles was measured, and the number average value thereof was calculated. The number average value of the lengths thus obtained was defined as “number average value of the protrusion height of the first particles”.

<Measurement method of first particle coverage>
Using a transmission electron microscope (TEM, “H-7100FA” manufactured by Hitachi High-Technologies Corporation), a TEM photograph (magnification 100000 times) of the toner base particles was taken. Next, the obtained TEM photograph of the toner base particles was binarized using image analysis software (“WinROOF” manufactured by Mitani Corporation). At this time, in the surface region of the toner core, the TEM of the toner base particle is clarified so that the region where the first particles (each of the first particles A to E) are provided and the region where the first particles are not provided are clear. Binarization processing was performed on the photograph. And the ratio of the 1st particle which occupies for the whole surface surface was computed using the projection area of the 1st particle. This operation was performed on ten TEM photographs (TEM photographs of toner mother particles), and the average value of the occupation ratio of the first particles was calculated. The average value thus obtained was defined as “first particle coverage”.

<Method for measuring thickness of shell layer>
First, a cross-sectional TEM photograph of the toner base particles was taken using a transmission electron microscope (TEM, “H-7100FA” manufactured by Hitachi High-Technologies Corporation). Next, a cross-sectional TEM photograph of the obtained toner base particles was analyzed using image analysis software (“WinROOF” manufactured by Mitani Corporation). Specifically, two straight lines perpendicular to the approximate center of the cross section of the toner base particles were drawn. In each of the two straight lines, the length from the interface between the toner core and the shell layer (corresponding to the surface of the toner core) to the surface of the shell layer was measured. The average value of the four lengths thus measured was taken as the thickness of the shell layer provided in one toner base particle. The thickness of the shell layer was measured for a plurality of toner base particles, and the average value of the thicknesses of the shell layers included in the plurality of toner base particles (measurement target) was obtained. The average value of the thickness of the shell layer thus obtained was defined as “shell layer thickness”.

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

[Toner Evaluation Method]
The following methods evaluated the heat-resistant storage stability of the toner, the toner charge amount, the toner scattering amount, and the fog density.

<Evaluation method of heat-resistant storage stability of toner>
First, 3 g of toner (each of toners T-1 to T-11) was put in a polyethylene container (capacity: 20 mL). The polyethylene container was placed in a thermostatic bath (set at 56 ° C.) and allowed to stand for 3 hours and 48 hours. The polyethylene container was taken out of the thermostatic bath and allowed to stand for 30 minutes in an environment having a temperature of 25 ° C. and a humidity of 65% RH. The toner was taken out of the polyethylene container and placed on a 325 mesh (aperture 45 μm) sieve (mass known). The sieve was attached to a powder tester (registered trademark) (“TYPE PT-E 84810” manufactured by Hosokawa Micron Corporation). Toner was wiped for 30 seconds under 5 memory conditions. The mass of the toner remaining on the sieve was measured, and the toner residue (unit:%) was calculated based on the following formula.
Residual amount of toner (unit:%) = mass of toner remaining on sieve (unit: g) × 100 / mass of toner in polyethylene container (3 g)

The evaluation criteria for the heat resistant storage stability of the toner are shown below. In addition, Table 2 shows the calculation result of the toner residue and the evaluation result of the heat resistant storage stability of the toner.
Good (◯): Toner residue is less than 10% Normal (Δ): Toner residue is 10% or more and less than 20% Poor (X): Toner residue is 20% or more

<Evaluation method of toner charge amount and toner scattering amount>
(Preparation method for evaluation)
First, a carrier was produced. Specifically, in 1350 parts by mass of water, 30.00 parts by mass of polyamideimide resin (copolymer of trimellitic anhydride and 4,4′-diaminodiphenylmethane) and 120.0 parts by mass of FEP (tetrafluoride) And a copolymer of ethylene and propylene hexafluoride). In this aqueous solution, 3.000 parts by mass of silica particles were dispersed. In this way, a carrier coat solution was obtained.

In a fluidized bed coating apparatus (“Spiraflow (registered trademark) SFC-5” manufactured by Freund Sangyo Co., Ltd.), 1500.0 parts by mass of carrier coat liquid and 10 × 10 ³ parts by mass of carrier core (manufactured by Powdertech Corporation “ EF-35B ", number average primary particle size 35 μm). The carrier coat liquid was sprayed on the carrier core using a fluidized bed coating apparatus. In this way, a carrier core coated with an uncured organic layer (fluidized bed) was obtained. The obtained powder was put into a box-type shelf dryer, heated at 250 ° C. for 1 hour, then cooled and crushed. In this way, a carrier was obtained. In the obtained carrier, the coating amount of the resin was 1.5% by mass.

  In a polyethylene container (capacity: 500 mL), 300 parts by mass of carrier and 30.0 parts by mass of toner (each of toners T-1 to T-11) were put. Using a mixer ("Turbler (registered trademark) mixer T2F" manufactured by Willy et Bacofen (WAB)), the contents of the polyethylene container were mixed for 30 minutes. In this way, an evaluation object was obtained.

(Evaluator preparation method)
An evaluation object and a toner of a color different from the evaluation object were put in the developing unit of a color multifunction machine (“TASKalfa 5550ci” manufactured by Kyocera Document Solutions Inc.). The toners of colors different from the evaluation target included magenta toner, yellow toner, and black toner. All of these toners were unused. Further, a replenishing toner (unused state) was placed in the toner container of the color multifunction peripheral. In this way, an evaluation machine was prepared.

(Evaluation methods)
Printing environment test (hereinafter referred to as "5% "Printing durability").

After 5% printing durability, the toner was removed from the developing section of the evaluation machine. The toner charge amount (charge amount after 5% printing durability) was measured by the following method. Specifically, 0.10 g of an evaluation target (carrier and toner) is placed in a measurement cell of a Q / m meter (Trek's “MODEL 210HS-1”), and only the toner of the evaluation target is passed through a sieve (wire mesh). Aspiration was performed for 10 seconds. Based on the following formula, the toner charge amount (unit: μC / g) was calculated.
Charge amount of toner (unit: μC / g) = total electric amount of sucked toner (unit: μC) / mass of sucked toner (unit: g)

The evaluation criteria for the charge amount after 5% printing durability are shown below. Table 2 shows the calculation results and evaluation results of the charge amount after 5% printing durability.
Good (◯): The charge amount after 5% printing durability is 20 μC / g or more and less than 40 μC / g. Poor (×): The charge amount after 5% printing durability is less than 20 μC / g or 40 μC / g or more.

In addition, after 5% printing durability, the mass of toner deposited on the toner receiving portion of the developing portion of the evaluation machine (hereinafter referred to as “toner scattering amount”) was measured. The evaluation criteria for the toner scattering amount are shown below. Table 2 shows the measurement results and evaluation results of the toner scattering amount.
Good (◯): Toner scattering amount is less than 0.5 g Normal (Δ): Toner scattering amount is 0.5 g or more and less than 1.0 g Poor (x): Toner scattering amount is 1.0 g or more

<Evaluation method of fog density>
The fog density was evaluated using the evaluator prepared by the method described above (Preparation Method of Evaluator). Specifically, first, under an environment of a temperature of 28 ° C. and a humidity of 65% RH, a character pattern having a printing rate of 2% was continuously printed on printing paper (A4 size) using an evaluator. Thereafter, a patch pattern having a printing rate of 100% was continuously printed on printing paper (A4 size) 1000 sheets.

Using a reflection densitometer (“RD914” manufactured by X-Rite), the reflection density of the blank portion (non-printing area) of the paper on which the patch pattern was printed was measured. The maximum value of the reflection density (the highest fog density among the reflection density of the blank portion of 1000 sheets) was defined as the fog density (FD). The evaluation standard of fog density (FD) is shown below. Table 2 shows the measurement results and evaluation results of the fog density (FD).
Good (◯): Fog density (FD) is 0.004 or less Normal (Δ): Fog density (FD) is more than 0.004 and less than 0.01 Poor (x): Fog density (FD) is 0.01 or more

  In Table 2, “charge amount” indicates the calculation result (unit: μC / g) of the charge amount after 5% printing durability, and the charge amount after 5% printing durability is indicated in parentheses of “charge amount”. The evaluation result is described. In “scattering amount”, the measurement result (unit: g) of the toner scattering amount is described, and in the parentheses of “scattering amount”, the evaluation result of the toner scattering amount is described. The measurement result of the fog density (FD) is described in “FD”, and the evaluation result of the fog density (FD) is described in parentheses of “FD”.

Each of the toners T-1 to T-5 (the toners according to Examples 1 to 5) has a charging property and includes a plurality of toner particles. Each toner particle was provided with toner base particles. The toner base particles each had a toner core, a plurality of first particles containing silica, and a shell layer. Each toner core contained a crystalline polyester resin and an amorphous polyester resin. Each of the first particles included an embedded portion embedded in the surface of the toner core and a protruding portion protruding outward in the radial direction of the toner particle from the surface of the toner core. The coverage of the first particles was 50% or more. The number average primary particle diameter R _{f of} the first particles was 200 nm or more and 500 nm or less. The shell layer covered the exposed part of the toner core and the surface of the protruding part of the first particles. The shell layer contained a positively charged resin. The thickness T of the shell layer was 20 nm or more and 50 nm or less.

  As shown in Table 2, each of the toners T-1 to T-5 was excellent in heat-resistant storage stability. In each of the toners T-1 to T-5, it was possible to prevent a decrease in the charge amount of the toner, to prevent scattering of the reversely charged toner, and to prevent occurrence of fogging.

  In the toner T-6 (toner according to Comparative Example 1), the number average primary particle diameter of the used first particles (first particles D) was smaller than those of the toners T-1 to T-5. Therefore, the spacer effect by the first particles could not be obtained sufficiently. Therefore, the heat resistant storage stability of the toner deteriorated.

  In the toner T-7 (toner according to Comparative Example 2), the number average primary particle diameter of the used first particles (first particles E) was larger than that in the toners T-1 to T-5. Therefore, the first particles are detached from the surface of the toner core during image formation (for example, during 5% printing durability). As a result, the charge amount of the toner decreased. Therefore, the scattering amount of the toner (toner having a reduced charge amount) is increased, and as a result, the formed image is fogged.

  In the toner T-8 (toner according to Comparative Example 3), the coverage of the first particles was lower than that in the toners T-1 to T-5. For this reason, the exposed portion of the toner core is increased, and the heat-resistant storage stability of the toner is deteriorated. In addition, since the coverage of the first particles is low, it is difficult to ensure the amount of the first particles existing on the inner side in the radial direction of the toner particles than the shell layer. Therefore, it is difficult to hold positive charges generated in the shell layer with the first particles during image formation (for example, during 5% printing durability). As a result, the charge amount of the toner decreased. Therefore, the scattering amount of the toner (toner having a reduced charge amount) increased, and as a result, the formed image was fogged.

  In the toner T-9 (toner according to Comparative Example 4), the thickness of the shell layer was smaller than that in the toners T-1 to T-5. Further, in the toner T-10 (the toner according to Comparative Example 5), no shell layer was formed. Therefore, in the toner T-9 and the toner T-10, the amount of the shell material (material constituting the shell layer) covering the first particles is small. As a result, the first particles are detached from the surface of the toner core during image formation (for example, during 5% printing durability). Therefore, the charge amount of the toner decreased. Therefore, the scattering amount of the toner (toner having a reduced charge amount) is increased, and as a result, the formed image is fogged.

  In the toner T-11 (the toner according to Comparative Example 6), the shell layer was thicker than the toners T-1 to T-5, respectively. Therefore, the amount of the shell material that covers the first particles is large. As a result, the first particles were buried in the surface of the toner core during image formation (for example, during 5% printing durability). Therefore, the charge amount of the toner decreased. Therefore, the scattering amount of the toner (toner having a reduced charge amount) is increased, and as a result, the formed image is fogged.

  The inventor has confirmed that the toners T-1 to T-5 are excellent in low-temperature fixability. Further, the present inventor has confirmed that the initial charge amount is remarkably reduced when a resin having negative chargeability (for example, phenol resin) is used as the shell resin.

  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 Toner Particle 20 Toner Base Particle 21 Toner Core 23 First Particle 25 Shell Layer 50 Toner Particle 52 External Additive Particle 231 Buried Portion 233 Protruding Portion

Claims (6)

A toner for developing an electrostatic latent image having a positive charging property,
The electrostatic latent image developing toner includes a plurality of toner particles,
Each of the toner particles includes toner mother particles,
The toner base particles each have a toner core, a plurality of first particles containing silica, and a shell layer;
Each of the toner cores contains a crystalline polyester resin and an amorphous polyester resin,
Each of the first particles includes an embedded portion embedded in the surface of the toner core, and a protruding portion protruding outward in the radial direction of the toner particle from the surface of the toner core,
Of the surface area of the toner core, the ratio of the area of the toner core covered with the first particles is 50% or more,
The number average primary particle diameter R _{f of} the first particles is 200 nm or more and 500 nm or less,
The shell layer covers a region of the surface of the toner core where the first particles are not provided and a surface of the protruding portion;
The shell layer contains a resin having positive chargeability stronger than the amorphous polyester resin,
The thickness T of the shell layer state, and are more 50nm or less 20 nm,
The electrostatic latent image developing toner, wherein the resin having positive chargeability stronger than that of the amorphous polyester resin is a styrene-acrylic acid resin . 2. The number average value H of the lengths of the protruding portions in the radial direction of the toner particles is 0.4 to 0.8 times the number average primary particle diameter R _f of the first particles. The electrostatic latent image developing toner according to 1.   The electrostatic latent image developing toner according to claim 1, wherein each of the first particles is a silica particle that has not been subjected to a hydrophobic treatment and a positive charging treatment on the surface. Each of the toner particles further comprises an external additive attached to the surface of the shell layer,
The external additive includes a plurality of external additive particles,
Each of the external additive particles includes particles formed by subjecting the surface of silica particles to a hydrophobic treatment and a positive charge treatment,
The electrostatic latent image developing toner according to claim 1, wherein the number average primary particle diameter R _{s of the} external additive particles is 10 nm or more and 40 nm or less. A method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 4 ,
Producing the toner core;
Embedding a portion of each of the first particles in the surface of the toner core;
Forming the shell layer on a region of the surface of the toner core where the first particles are not provided and on the surface of the protruding portion;
A method for producing a toner for developing an electrostatic latent image, comprising: The method for producing a toner for developing an electrostatic latent image according to claim 5 , wherein the step of producing the toner core includes a step of producing the toner core by a pulverization method.

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