JP2024046533A - Electrostatic charge image developing toner, electrostatic charge image developer, toner cartridge, process cartridge, image forming device, and image forming method - Google Patents

Abstract

To provide an electrostatic charge image developing toner that is less likely to cause color unevenness.SOLUTION: An electrostatic charge image developing toner provided herein comprises toner particles, silica particles (A) containing a nitrogen element-containing compound containing a molybdenum element, and inorganic particles (B) other than the silica particles (A). The silica particles (A) feature a ratio NMo/NSi of molybdenum element Net intensity NMo to silicon element Net intensity NSi in a range of 0.035 to 0.45, inclusive, as measured by fluorescent X-ray analysis, and the inorganic particles (B) have an average primary particle diameter in a range of 10 to 80 nm, inclusive.SELECTED DRAWING: None

Description

The present disclosure relates to an electrostatic image developing toner, an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method.

Patent Document 1 discloses a toner comprising toner base particles and an external additive attached to the surface of the toner base particles, the external additive including a first silica powder having a volume median diameter of 15 nm or more and 25 nm or less and an electrical resistivity of 1.0×10 ¹⁵ Ω·cm or more and a second silica powder having a volume median diameter of 70 nm or more and 120 nm or less, an electrical resistivity of 85 Ω·cm or less and a density of 2.8 g/cm ³ or less.

Patent document 2 discloses a toner that includes toner base particles that contain a binder resin and a colorant, and an external additive, in which the external additive includes non-spherical particles and spherical particles, the non-spherical particles are secondary particles formed by bonding together spherical primary particles, and the non-spherical particles and the spherical particles satisfy formula (1).

Patent document 3 discloses a toner for developing electrostatic images, which is composed of toner particles and additives, and in which the additives contain hydrophobized silica and positively charged silica, and the amount of hydrophobized silica added to the toner and the BET specific surface area, the amount of positively charged silica added to the toner and the BET specific surface area, and the volume average particle diameter of the toner particles satisfy the relationship of formula (1).

Patent Document 4 discloses silica particles which contain a quaternary ammonium salt, in which the ratio F BEFORE /F AFTER of the maximum value F _BEFORE of the frequency of pores having a diameter of 2 nm or less obtained from a pore distribution curve of silica particles before washing, as determined from a nitrogen gas adsorption method, to the maximum value F _AFTER of the frequency of pores having a diameter of 2 nm or less obtained from a pore distribution curve of silica particles after washing, as determined from a nitrogen gas adsorption method, is 0.90 or more and 1.10 or less, and the ratio F _SINTERING /F _BEFORE of the maximum value F _BEFORE to the maximum value F _SINTERING of the frequency of pores having a diameter of 2 nm or less obtained from a pore distribution curve of silica particles after baking the silica particles _{before washing at 600° C. ,} is 5 or more and 20 or less.

Patent Document 5 discloses a toner for developing an electrostatic latent image containing toner particles to which an external additive is attached to the surface of toner base particles containing a binder resin and a colorant, wherein the toner base particles are bound. A toner for developing electrostatic latent images is disclosed which contains a polyester resin as a resin and contains silica particles and titanium oxide particles or metatitanic acid particles as external additives.

JP 2019-056807 A Japanese Patent Application Publication No. 2013-190648 Japanese Patent Application Laid-Open No. 8-123073 JP 2021-151944 A JP 2015-094875 A

The present disclosure has an object to provide a toner for developing electrostatic images, which is less prone to color unevenness in silica particles having a nitrogen _- containing compound containing molybdenum externally added to the toner particles, compared to a case in which the ratio _NMo / _NSi of the net intensity NMo of _molybdenum to the net intensity NSi of silicon measured by fluorescent X-ray analysis is less than 0.035 or exceeds 0.45.

Means for solving the above problems include the following aspects.

＜1＞
Toner particles;
silica particles (A) containing a nitrogen-containing compound containing molybdenum, which is externally added to the toner particles;
and inorganic particles (B) other than the silica particles (A) that are externally added to the toner particles,
The silica particles (A) have a ratio _NMo / _NSi of a net intensity NMo of molybdenum element to _a net intensity _NSi of silicon element, which is measured by fluorescent X-ray analysis, of 0.035 or more and 0.45 or less;
The inorganic particles (B) have an average primary particle size of 10 nm or more and 80 nm or less.
Toner for developing electrostatic images.
＜2＞
The toner for developing an electrostatic image according to <1>, wherein the ratio N _Mo /N _Si of the silica particles (A) is 0.05 or more and 0.30 or less.
＜3＞
The toner for developing an electrostatic image according to <1> or <2>, wherein, when the overall circularity of the silica particles (A) and the inorganic particles (B) externally added to the toner particles is measured, the circularity distribution has at least two peaks, with at least one peak being in a region where the circularity is more than 0.88 and at least one peak being in a region where the circularity is 0.88 or less.
＜4＞
The toner for developing an electrostatic image according to any one of <1> to <3>, wherein the inorganic particles (B) contain silica particles (B) other than the silica particles (A).
＜5＞
The toner for developing electrostatic images according to any one of <1> to <4>, wherein the inorganic particles (B) contain titanium compound particles.
＜6＞
The toner for developing electrostatic images according to any one of <1> to <4>, wherein the inorganic particles (B) contain strontium titanate particles.
＜７＞
The toner for developing electrostatic images according to any one of <1> to <5>, wherein the inorganic particles (B) contain silica particles (B) other than the silica particles (A) and titanium compound particles.
＜8＞
The toner for developing electrostatic images according to <7>, wherein the content of the titanium compound particles is 0.1 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the toner particles.
＜9＞
The toner for developing electrostatic images according to any one of <1> to <6>, wherein the inorganic particles (B) contain silica particles (B) other than the silica particles (A) and strontium titanate particles.
＜10＞
The toner for developing electrostatic images according to <9>, wherein the content of the strontium titanate particles is 0.1 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the toner particles.
<11>
The toner for developing electrostatic images according to any one of <1> to <10>, wherein the inorganic particles (B) have a volume resistivity of 1.0×10 ¹⁴ Ω·cm or more and 1.0×10 ¹⁷ Ω·cm or more.
＜12＞
The toner for developing an electrostatic image according to any one of <1> to <11>, wherein a surface coverage rate Ca of the toner particles by the silica particles (A) and a surface coverage rate Cb of the toner particles by the inorganic particles (B) satisfy a relationship of 0.20≦Ca/(Ca+Cb)≦0.75.
＜13＞
The toner for developing an electrostatic image according to <12>, wherein a surface coverage Ca of the toner particles by the silica particles (A) is 10% or more and 60% or less.
＜14＞
The toner for developing electrostatic images according to any one of <1> to <13>, wherein a ratio Da/Db of an average primary particle diameter Da of the silica particles (A) to an average primary particle diameter Db of the inorganic particles (B) is 1 or more and 10 or less.
＜15＞
The toner for developing electrostatic images according to any one of <1> to <14>, wherein the nitrogen-containing compound containing molybdenum is at least one selected from the group consisting of a quaternary ammonium salt containing molybdenum, and a mixture of a quaternary ammonium salt and a metal oxide containing molybdenum.
＜16＞
The toner for developing an electrostatic image according to any one of <1> to <15>, wherein the silica particles (A) are silica particles having a coating structure made of a reaction product of a silane coupling agent and the nitrogen-containing compound containing molybdenum attached to the coating structure.
＜１７＞
The toner for developing electrostatic images according to <16>, wherein the silane coupling agent contains an alkyltrialkoxysilane.

<18>
An electrostatic image developer comprising the electrostatic image developing toner according to any one of <1> to <17>.
<19>
Containing the electrostatic image developing toner according to any one of <1> to <17>,
A toner cartridge that can be attached to and removed from an image forming apparatus.
<20>
A developing device containing the electrostatic image developer according to <18> and developing an electrostatic image formed on the surface of the image carrier as a toner image by the electrostatic image developer,
A process cartridge that can be attached to and removed from an image forming apparatus.
<21>
an image holder;
Charging means for charging the surface of the image carrier;
an electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
A developing means that contains the electrostatic image developer according to <18> and develops the electrostatic image formed on the surface of the image carrier as a toner image with the electrostatic image developer;
a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
a fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising:
<22>
a charging step of charging the surface of the image carrier;
an electrostatic charge image forming step of forming an electrostatic charge image on the surface of the charged image carrier;
A developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to <18>;
a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
a fixing step of fixing the toner image transferred to the surface of the recording medium;
An image forming method comprising:

According to the invention related to <1>, <3>, <4>, <5>, <6>, <7>, <9>, <11>, <15>, <16> or <17>, there is provided a toner for developing electrostatic images, in which, in silica particles having a nitrogen-containing compound containing molybdenum externally added to the toner particles, the ratio _NMo / _NSi of the net intensity NMo of molybdenum to the net intensity NSi of silicon measured by fluorescent X-ray analysis is less than 0.035 or exceeds 0.45, which is less than the case where the ratio _NMo /NSi is less than the case where the ratio NMo/NSi is less than the case where the ratio NMo/NSi is less than the case where the ratio NMo/ _NSi is more than the case where the ratio NSi is less than the case where the ratio NMo/NSi is less than the case where the ratio NSi is more than the case where the ratio N ...
According to the invention related to <2>, there is provided a toner for developing electrostatic images, in which, in silica particles having a nitrogen-containing compound containing molybdenum externally added to the toner particles, the ratio _NMo /NSi of the net intensity NMo of molybdenum to the net intensity _NSi of silicon measured by fluorescent X-ray analysis is less than 0.05 or exceeds 0.30, which is less than the case where the ratio _NMo / _NSi ...
According to the invention related to <8>, there is provided a toner for developing electrostatic images which is less prone to color unevenness compared to a case in which the inorganic particles (B) contain silica particles (B) other than the silica particles (A) and titanium compound particles, and the content of the titanium compound particles is less than 0.1 part by mass or more than 1.0 part by mass per 100 parts by mass of the toner particles.
According to the invention related to <10>, there is provided a toner for developing electrostatic images which is less prone to color unevenness compared to a case in which the inorganic particles (B) contain silica particles (B) other than the silica particles (A) and strontium titanate particles, and the content of the strontium titanate particles is less than 0.1 part by mass or more than 1.0 part by mass per 100 parts by mass of the toner particles.
According to the invention related to <12>, there is provided a toner for developing electrostatic images which is less prone to color unevenness, compared to a case in which the surface coverage rate Ca of the toner particles by the silica particles (A) and the surface coverage rate Cb of the toner particles by the inorganic particles (B) do not satisfy the relationship of 0.20≦Ca/(Ca+Cb)≦0.75.
According to the invention related to <13>, there is provided a toner for developing electrostatic images which is less prone to color unevenness, compared with a toner particle having a surface coverage Ca of the silica particles (A) of less than 10% or more than 60%.
According to the invention related to <14>, there is provided a toner for developing electrostatic images which is less prone to color unevenness, as compared with a case in which the ratio Da/Db of the average primary particle diameter Da of the silica particles (A) to the average primary particle diameter Db of the inorganic particles (B) is less than 1 or exceeds 10.

According to the invention according to <18>, in the silica particles having the nitrogen element-containing compound containing the molybdenum element externally added to the toner particles, the net intensity N _Mo of the molybdenum element measured by fluorescent X-ray analysis and the silicon An electrostatic image developer is provided that is less likely to cause color unevenness than when the ratio N _Mo /N _Si of the element to the net strength N _Si is less than 0.035 or more than 0.45.
According to the invention according to <19>, in the silica particles having the nitrogen element-containing compound containing the molybdenum element externally added to the toner particles, the net intensity N _Mo of the molybdenum element measured by fluorescent X-ray analysis and the silicon A toner cartridge in which color unevenness is less likely to occur is provided than when the ratio N _Mo /N _Si of the element to the net strength N _Si is less than 0.035 or more than 0.45.
According to the invention according to <20>, in the silica particles having the nitrogen element-containing compound containing the molybdenum element externally added to the toner particles, the net intensity N _Mo of the molybdenum element measured by fluorescent X-ray analysis and the silicon A process cartridge is provided in which color unevenness is less likely to occur compared to when an electrostatic image developer in which the ratio N _Mo /N _Si of the element to the net strength N _Si is less than 0.035 or more than 0.45 is applied. Ru.
According to the invention according to <21>, in the silica particles having the nitrogen element-containing compound containing the molybdenum element externally added to the toner particles, the net intensity N _Mo of the molybdenum element measured by fluorescent X-ray analysis and the silicon Provided is an image forming apparatus in which color unevenness is less likely to occur than when using an electrostatic image developer in which the ratio N _Mo /N _Si of the element to Net strength N _Si is less than 0.035 or more than 0.45. be done.
According to the invention according to <22>, in the silica particles having the nitrogen element-containing compound containing the molybdenum element externally added to the toner particles, the net intensity N _Mo of the molybdenum element measured by fluorescent X-ray analysis and the silicon Provided is an image forming method in which color unevenness is less likely to occur than when using an electrostatic image developer in which the ratio N _Mo /N _Si of the element to Net strength N _Si is less than 0.035 or more than 0.45. be done.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating an example of a process cartridge that is detachably mounted to the image forming apparatus according to the present embodiment.

Embodiments of the present disclosure will be described below. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the embodiments.

In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

In the present disclosure, the term "step" is included not only in an independent step but also in the case where the purpose of the step is achieved even if the step cannot be clearly distinguished from other steps.

When embodiments of this disclosure are described with reference to drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the sizes of components in each drawing are conceptual, and the relative relationships between the sizes of components are not limited to these.

In the present disclosure, each component may contain multiple types of corresponding substances. When referring to the amount of each component in a composition in this disclosure, if there are multiple types of substances corresponding to each component in the composition, unless otherwise specified, the amount of each component in the composition is means the total amount of substance.
In the present disclosure, each component may include a plurality of types of particles. When a plurality of types of particles corresponding to each component are present in the composition, the particle diameter of each component means a value for a mixture of the plurality of types of particles present in the composition, unless otherwise specified.

In this disclosure, "(meth)acrylic" refers to both acrylic and methacrylic, and "(meth)acrylate" refers to both acrylate and methacrylate.

In the present disclosure, the "toner for developing an electrostatic image" is also referred to as a "toner", the "developing agent for an electrostatic image" is also referred to as a "developer", and the "carrier for developing an electrostatic image" is also referred to as a "carrier".

<Toner for electrostatic image development>
The toner according to the present embodiment includes toner particles, silica particles (A) externally added to the toner particles, and inorganic particles (B) other than the silica particles (A) externally added to the toner particles. The silica particles (A) contain a nitrogen element-containing compound containing a molybdenum element and have a ratio of the net strength N _Mo of the molybdenum element to the net strength N _Si of the silicon element measured by X-ray fluorescence analysis N _Mo /N _Si is 0.035 or more and 0.45 or less. The inorganic particles (B) have an average primary particle size of 10 nm or more and 80 nm or less.

The toner according to this embodiment is less likely to cause color unevenness in images. The mechanism is presumed to be as follows.

Conventionally, nitrogen-containing compounds containing molybdenum (e.g., quaternary ammonium molybdate) have been known as charge control agents for toners, and silica particles having nitrogen-containing compounds containing molybdenum attached to their surfaces have also been known as external toner additives.
By covering the surface of the toner particles with an external additive having a relatively small particle size (for example, 10 nm or more and 80 nm or less) and adding the silica particles, the toner can be charged appropriately. Nevertheless, in image formation where the toner is frequently exposed to an electric field (for example, image formation where multiple color toners are layered on an intermediate transfer body), inappropriate charge transfer between toners occurs, which causes the toner to become excessively negatively charged, which can impair the uniformity of transfer when transferred to a recording medium, and cause color unevenness in the image. On the other hand, inappropriate charge transfer between toners can also cause local charge leakage, which can cause charging unevenness, which can impair the uniformity of transfer when transferred to a recording medium, and cause color unevenness in the image.
In response to this, the present inventors have discovered that the occurrence of color unevenness can be suppressed by adjusting the amount of molybdenum in the silica particles.

In this embodiment, the ratio N _Mo /N _Si of the silica particles (A) is 0.035 or more and 0.45 or less.
If the ratio N _Mo /N _Si is less than 0.035, local charge leakage occurs, leading to uneven charging and color unevenness. From the viewpoint of suppressing this phenomenon, the ratio N _Mo /N _Si is 0.035 or more, preferably 0.05 or more, more preferably 0.07 or more, and even more preferably 0.10 or more.
When the ratio N _Mo /N _Si exceeds 0.45, the toner becomes excessively negatively charged, leading to the occurrence of color unevenness. From the viewpoint of suppressing this phenomenon, the ratio N _Mo /N _Si is 0.45 or less, preferably 0.40 or less, more preferably 0.35 or less, and even more preferably 0.30 or less.

In the toner according to this embodiment, when the overall circularity of the silica particles (A) and inorganic particles (B) externally added to the toner particles is measured, it is preferable that the circularity distribution has at least two peaks, with at least one peak in a region where the circularity is greater than 0.88 and at least one peak in a region where the circularity is 0.88 or less.
External additive particles having at least one peak in the region of circularity exceeding 0.88 are easy to move on the toner particle surface, and external additive particles having at least one peak in the region of circularity equal to or less than 0.88 are difficult to move on the toner particle surface. It is presumed that by externally adding both particles that are easy to move on the toner particle surface and particles that are difficult to move on the toner particle surface, the silica particles (A) and inorganic particles (B) as a whole are dispersed and arranged with high uniformity on the toner particle surface, and the arrangement is maintained.

In the above embodiment, it is preferable that at least one of the peaks in the region where the circularity is greater than 0.88 is a peak derived from silica particles (A), and it is preferable that at least one of the peaks in the region where the circularity is 0.88 or less is a peak derived from inorganic particles (B).

The method for determining the overall circularity distribution of the silica particles (A) and the inorganic particles (B) is as follows.
Using a scanning electron microscope (SEM) (manufactured by Hitachi High-Technologies, S- ⁴⁸⁰⁰ ) equipped with an energy dispersive X-ray analyzer (EDX device) (manufactured by Horiba, Ltd., EMAX Evolution Photograph the toner at double magnification. When resin particles are externally added, the externally added resin particles are excluded by EDX analysis. A total of 400 silica particles (A) and inorganic particles (B) are randomly identified from within one field of view without distinguishing them. Images of 400 particles are analyzed using image processing analysis software WinRoof (Mitani Shoji Co., Ltd.). The area and perimeter of each primary particle image are determined, and circularity=4π×(area of particle image)÷(perimeter of particle image) ² is calculated. Draw 400 circularity distribution curves.

The composition of the toner according to this embodiment is described in detail below.

[Toner particles]
The toner particles include, for example, a binder resin, and if necessary, a colorant, a release agent, and other additives.

- Binder resin -
Examples of the binder resin include vinyl resins made of homopolymers of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), or copolymers of two or more of these monomers.
Examples of the binder resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin, mixtures of these with the vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in the presence of these.
These binder resins may be used alone or in combination of two or more kinds.

As the binder resin, polyester resin is suitable.
Examples of the polyester resin include known polyester resins.

Examples of polyester resins include condensation polymers of polyhydric carboxylic acids and polyhydric alcohols. As the polyester resin, a commercially available product or a synthesized product may be used.

Examples of polycarboxylic acids include aliphatic dicarboxylic acids (eg, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid, etc.) , alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc.), anhydrides thereof, or lower grades thereof (e.g., carbon atoms with 1 or more carbon atoms). 5 or less) alkyl esters. Among these, as the polyhydric carboxylic acid, for example, aromatic dicarboxylic acids are preferable.
As the polyvalent carboxylic acid, a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure may be used together with the dicarboxylic acid. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, carbon atoms of 1 to 5) alkyl esters thereof.
One type of polyhydric carboxylic acid may be used alone, or two or more types may be used in combination.

Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, Hydrogenated bisphenol A, etc.), aromatic diols (eg, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, etc.). Among these, as the polyhydric alcohol, aromatic diols and alicyclic diols are preferred, and aromatic diols are more preferred.
As the polyhydric alcohol, a trivalent or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used together with the diol. Examples of the trivalent or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
One type of polyhydric alcohol may be used alone, or two or more types may be used in combination.

The glass transition temperature (Tg) of the polyester resin is preferably 50°C or more and 80°C or less, more preferably 50°C or more and 65°C or less.
The glass transition temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC). It is determined by the outer glass transition start temperature.

The weight average molecular weight (Mw) of the polyester resin is preferably 5,000 or more and 1,000,000 or less, more preferably 7,000 or more and 500,000 or less.
The number average molecular weight (Mn) of the polyester resin is preferably 2,000 or more and 100,000 or less.
The molecular weight distribution Mw/Mn of the polyester resin is preferably 1.5 or more and 100 or less, more preferably 2 or more and 60 or less.
Weight average molecular weight and number average molecular weight are measured by gel permeation chromatography (GPC). Molecular weight measurement by GPC is performed using a Tosoh GPC/HLC-8120GPC as a measurement device, a Tosoh column/TSKgel SuperHM-M (15 cm), and a THF solvent. The weight average molecular weight and number average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared using a monodisperse polystyrene standard sample.

Polyester resin can be obtained by a known manufacturing method. Specifically, it can be obtained, for example, by a method in which the polymerization temperature is set at 180° C. or higher and 230° C. or lower, and if necessary, the pressure inside the reaction system is reduced to allow the reaction to occur while removing water and alcohol generated during condensation.
If the raw material monomers are not dissolved or miscible at the reaction temperature, a high boiling point solvent may be added as a solubilizing agent to dissolve them. In this case, the polycondensation reaction is carried out while distilling off the solubilizing agent. If there are monomers with poor compatibility, it is recommended to condense the monomer with poor compatibility and the acid or alcohol to be polycondensed in advance before polycondensing it with the main component. .

The content of the binder resin is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and even more preferably 60% by mass or more and 85% by mass or less, based on the total amount of the toner particles.

-Coloring agent-
Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzidine yellow, thren yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant. Carmine 6B, DuPont Oil Red, Pyrazolone Red, Lysole Red, Rhodamine B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Pigments such as malachite green oxalate; acridine series, xanthene series, azo series, benzoquinone series, azine series, anthraquinone series, thioindico series, dioxazine series, thiazine series, azomethine series, indico series, phthalocyanine series, aniline black series, polymethine series , triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes; and inorganic pigments such as titanium compounds and silica.

The colorant is not limited to a substance that absorbs light in the visible light region, and may be, for example, a substance that absorbs light in the near infrared region, or may be a fluorescent colorant.
Examples of colorants having absorption in the near infrared region include aminium salt compounds, naphthalocyanine compounds, squarylium compounds, and croconium compounds.
Examples of fluorescent colorants include the fluorescent colorants described in paragraph 0027 of JP-A-2021-127431.

The coloring agent may be a coloring agent having glittering properties. As a coloring agent with brightness, metal powder such as aluminum, brass, bronze, nickel, stainless steel, zinc, etc.; mica coated with titanium oxide or yellow iron oxide; barium sulfate, layered silicate, layered aluminum silicate, etc. coated flaky inorganic crystal substrate; single crystal plate titanium oxide, basic carbonate, bismuth oxychloride, natural guanine, flaky glass powder, metal-deposited flaky glass powder; and the like.

One type of coloring agent may be used alone, or two or more types may be used in combination.
The colorant may be surface-treated if necessary, or may be used in combination with a dispersant.

In this embodiment, the toner particles may contain a colorant or may not contain a colorant. The toner according to this embodiment may be a so-called transparent toner, which is a toner that does not contain a colorant in its toner particles.
In the present embodiment, when the toner particles do not contain a colorant, the toner according to the embodiment has the effect that unevenness in image gloss and/or brightness is less likely to occur.

In this embodiment, when the toner particles contain a colorant, the content of the colorant is preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less, based on the total amount of the toner particles.

-Release agent-
Examples of the release agent include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral/petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montan acid esters. The release agent is not limited to these.

The melting temperature of the release agent is preferably 50° C. or higher and 110° C. or lower, and more preferably 60° C. or higher and 100° C. or lower.
The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) based on the "melting peak temperature" described in the method for determining melting temperature in JIS K7121-1987 "Method for measuring transition temperature of plastics."

The content of the release agent 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, based on the total mass of the toner particles.

-Other additives-
Examples of other additives include known additives such as magnetic substances, charge control agents, and inorganic powders. These additives are included in the toner particles as internal additives.

-Characteristics of toner particles, etc.-
The toner particles may be toner particles with a single-layer structure, or may be toner particles with a so-called core-shell structure composed of a core part (core particle) and a coating layer (shell layer) covering the core part. You can.
Toner particles with a core-shell structure include, for example, a core including a binder resin and optionally other additives such as a colorant and a release agent, and a binder resin. It is preferable to include a covering layer.

The volume average particle diameter (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, more preferably 4 μm or more and 8 μm or less, and even more preferably 4 μm or more and 6 μm or less.

Various average particle diameters and various particle size distribution indices of the toner particles are measured using Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using ISOTON-II (manufactured by Beckman Coulter).
In the measurement, 0.5 mg or more and 50 mg or less of the measurement sample is added to 2 ml of a 5% by mass aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant. This is added to 100 ml or more and 150 ml or less of an electrolytic solution.
The electrolyte in which the sample was suspended was dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles in the range of 2 μm to 60 μm was measured using Coulter Multisizer II using an aperture with an aperture diameter of 100 μm. do. The number of particles to be sampled is 50,000.
Based on the measured particle size distribution, draw a cumulative distribution of the volume and number from the small diameter side for the divided particle size range (channel), and calculate the particle size that gives a cumulative 16% as the volume particle size D16v and the number particle size. D16p, the particle size that gives a cumulative 50% is defined as a volume average particle size D50v, the cumulative number average particle size D50p, and the particle size that gives a cumulative 84% as a volume particle size D84v, and a number particle size D84p.
Using these, the volume particle size distribution index (GSDv) is calculated as (D84v/D16v) ^1/2 and the number particle size distribution index (GSDp) is calculated as (D84p/D16p) ^1/2 .

The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less.

The average circularity of the toner particles is determined by (circle equivalent perimeter)/(perimeter) [(perimeter of a circle having the same projected area as the particle image)/(perimeter of the projected particle image)]. Specifically, it is a value measured by the following method.
First, toner particles to be measured are collected by suction, formed into a flat flow, and instantaneously flashed with a strobe to capture a still image of the particles.The flow-type particle image analyzer (Sysmex Corporation) Calculated using FPIA-3000 (manufactured by Co., Ltd.). The number of samples to be used when determining the average circularity is 3,500.
When the toner has an external additive, the toner (developer) to be measured is dispersed in water containing a surfactant, and then subjected to ultrasonic treatment to obtain toner particles from which the external additive has been removed.

[Silica particles (A)]
The silica particles (A) have a nitrogen element-containing compound containing molybdenum element, and have a ratio N _Mo of the net intensity N _Mo of the molybdenum element and the Net intensity N _Si of the silicon element measured by X-ray fluorescence analysis. /N _Si is 0.035 or more and 0.45 or less.
Hereinafter, "a nitrogen element-containing compound containing a molybdenum element" will be referred to as a "molybdenum nitrogen-containing compound".

The net strength N _Mo of the molybdenum element of the silica particles (A) is, from the viewpoint of narrowing the charge distribution and maintaining the charge distribution, and from the viewpoint of dispersing the silica particles (A) with high uniformity on the toner particle surface, preferably 5 kcps or more and 75 kcps or less, more preferably 7 kcps or more and 55 kcps or less, even more preferably 8 kcps or more and 50 kcps or less, and even more preferably 10 kcps or more and 40 kcps or less.

The method for measuring the net strength N _Mo of molybdenum element and the net strength N _Si of silicon element in silica particles is as follows.
Approximately 0.5 g of silica particles is compressed with a compression molding machine under a load of 6 t for 60 seconds to produce a disk with a diameter of 50 mm and a thickness of 2 mm. This disk is used as a sample and qualitative and quantitative elemental analysis is performed under the following conditions using a scanning X-ray fluorescence analyzer (XRF-1500, manufactured by Shimadzu Corporation) to determine the net strength (unit: kilo counts per second, kcps) of each of the molybdenum element and the silicon element.
Tube voltage: 40 kV
Tube current: 90mA
Measurement area (analysis diameter): 10 mm diameter
Measurement time: 30 minutes Anticathode: Rhodium

The amount of silica particles (A) added externally is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.1 parts by mass or more and 2.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1.0 parts by mass or less, relative to 100 parts by mass of toner particles.

The mass-based ratio Ma/Mb between the content Ma of silica particles (A) and the content Mb of inorganic particles (B) contained in the toner is preferably 1.0 or more and 5.0 or less, and 1.0 or more and 4 It is preferably .0 or less, and more preferably 1.0 or more and 2.0 or less.
It is considered that when the ratio Ma/Mb is 1.0 or more, electric charge leaks appropriately and the toner is not excessively negatively charged, and as a result, the occurrence of color unevenness in the image is further suppressed.
It is considered that when the ratio Ma/Mb is 5.0 or less, electric charge leaks to an appropriate extent and the toner is not excessively negatively charged, and as a result, the occurrence of color unevenness in images is further suppressed.

The silica particles (A) have a molybdenum nitrogen-containing compound. Hereinafter, a preferred structure of the silica particles (A) will be explained.

An embodiment of the silica particles (A) is a silica particle in which at least a portion of the surface of the silica mother particle is coated with a reaction product of a silane coupling agent, and a molybdenum nitrogen-containing compound is attached to the coating structure of the reaction product. can be mentioned. In this embodiment, a hydrophobized structure (a structure formed by treating silica particles with a hydrophobizing agent) may be further attached to the coating structure of the reaction product. The silane coupling agent is preferably at least one selected from the group consisting of a monofunctional silane coupling agent, a bifunctional silane coupling agent, and a trifunctional silane coupling agent, and more preferably a trifunctional silane coupling agent.

-Silica base particles-
The silica base particles may be dry silica or wet silica.
Examples of dry silica include combustion method silica (fumed silica) obtained by burning a silane compound; deflagration method silica obtained by explosively burning metal silicon powder;
Wet silica is obtained by the neutralization reaction of sodium silicate and mineral acid (precipitated silica synthesized and aggregated under alkaline conditions, gel silica particles synthesized and aggregated under acidic conditions); and sol-gel silica obtained by hydrolysis of an organic silane compound (for example, alkoxysilane). As the silica base particles, sol-gel silica is preferable from the viewpoint of narrowing the charge distribution and from the viewpoint that the shape (for example, circularity) can be adjusted relatively easily.

-Reaction products of silane coupling agents-
The structure made of the reaction product of the silane coupling agent (particularly, the reaction product of the trifunctional silane coupling agent) has a pore structure and has high affinity with the molybdenum nitrogen-containing compound, so that the molybdenum nitrogen-containing compound penetrates deep into the pores, and the content of the molybdenum nitrogen-containing compound contained in the silica particles (A) becomes relatively large.
The surface of the silica base particle is negatively charged, and the molybdenum nitrogen-containing compound, which is positively charged, is attached to the silica base particle, thereby generating an effect of canceling the excessive negative charge of the silica base particle.The molybdenum nitrogen-containing compound is attached not to the outermost surface of the silica particle (A) but to the inside of the coating structure made of the reaction product of the silane coupling agent, so that the charge distribution of the silica particle (A) does not spread to the positive charge side, and the charge distribution of the silica particle (A) is narrowed by canceling the excessive negative charge of the silica base particle.In addition, since the molybdenum nitrogen-containing compound is attached not to the outermost surface of the silica particle (A) but to the inside of the coating structure made of the reaction product of the silane coupling agent, it is considered that the charge leaks moderately, and the excessive negative charge of the toner is suppressed.

The silane coupling agent is preferably a compound that does not contain N (nitrogen element). Examples of the silane coupling agent include a silane coupling agent represented by the following formula (TA).
Formula (TA) R ¹ _n -Si(OR ² ) _4-n
In formula (TA), R ¹ is a saturated or unsaturated aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 20 carbon atoms, and R ² is a halogen atom or an alkyl group. and n is 1, 2 or 3. When n is 2 or 3, a plurality of R ¹ may be the same group or different groups. When n is 1 or 2, the plurality of R ² may be the same group or different groups.

The reaction product of the silane coupling agent is, for example, a reaction product in which all or part of OR ² is substituted with an OH group in formula (TA); all or part of the group in which OR ² is substituted with an OH group A reaction product in which all or a part of the group in which OR ² is substituted with an OH group is polycondensed with the SiOH group of the silica mother particle.

The aliphatic hydrocarbon group represented by R ¹ in formula (TA) may be linear, branched or cyclic, and is preferably linear or branched. The carbon number of the aliphatic hydrocarbon group is preferably 1 to 20, more preferably 1 to 18, even more preferably 1 to 12, and even more preferably 1 to 10. The aliphatic hydrocarbon group may be either saturated or unsaturated, but is preferably a saturated aliphatic hydrocarbon group, and more preferably an alkyl group. The hydrogen atom of the aliphatic hydrocarbon group may be substituted with a halogen atom.

Examples of saturated aliphatic hydrocarbon groups include linear alkyl groups (methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, hexadecyl, and icosyl groups, etc.), branched alkyl groups (isopropyl, isobutyl, isopentyl, neopentyl, 2-ethylhexyl, tertiary butyl, tertiary pentyl, and isopentadecyl groups, etc.), and cyclic alkyl groups (cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, tricyclodecyl, norbornyl, and adamantyl groups, etc.).

Examples of unsaturated aliphatic hydrocarbon groups include alkenyl groups (vinyl group (ethenyl group), 1-propenyl group, 2-propenyl group, 2-butenyl group, 1-butenyl group, 1-hexenyl group, 2-dodecenyl group, pentenyl group, etc.), alkynyl groups (ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 3-hexynyl group, 2-dodecynyl group, etc.).

The aromatic hydrocarbon group represented by ^R1 in formula (TA) preferably has 6 to 20 carbon atoms, more preferably 6 to 18 carbon atoms, even more preferably 6 to 12 carbon atoms, and even more preferably 6 to 10 carbon atoms. Examples of the aromatic hydrocarbon group include a phenylene group, a biphenylene group, a terphenylene group, a naphthalene group, and an anthracene group. The hydrogen atom of the aromatic hydrocarbon group may be substituted with a halogen atom.

Examples of the halogen atom represented by R ² in formula (TA) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom, a bromine atom, or an iodine atom is preferred.

The alkyl group represented by ^R2 in formula (TA) is preferably an alkyl group having from 1 to 10 carbon atoms, more preferably from 1 to 8, and even more preferably from 1 to 4. Examples of the linear alkyl group having from 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Examples of the branched alkyl group having 3 to 10 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, etc. Examples of the cyclic alkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl group formed by linking these monocyclic alkyl groups. The hydrogen atoms of the alkyl group may be substituted with halogen atoms.

n in formula (TA) is 1, 2 or 3, preferably 1 or 2, and more preferably 1.

In the silane coupling agent represented by formula (TA), R ¹ is a saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, and R ² is a halogen atom or an alkyl group having 1 to 10 carbon atoms. A trifunctional silane coupling agent in which n is 1 is preferred.

Examples of the trifunctional silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, and n-octyltrimethoxysilane. Methoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, butyltriethoxysilane, hexyltriethoxysilane, decyltriethoxysilane, dodecyltriethoxysilane, phenyltrimethoxysilane, o- Methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, phenyltriethoxysilane, benzyltriethoxysilane, decyltrichlorosilane, phenyltrichlorosilane (wherein R ¹ in formula (TA) is an unsubstituted aliphatic carbonized Compounds that are hydrogen groups or unsubstituted aromatic hydrocarbon groups); 3-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane , γ-glycidyloxypropylmethyldimethoxysilane (a compound in which R ¹ in formula (TA) is a substituted aliphatic hydrocarbon group or a substituted aromatic hydrocarbon group); One type of trifunctional silane coupling agent may be used alone, or two or more types may be used in combination.

As the trifunctional silane coupling agent, an alkyltrialkoxysilane is preferable, and in the formula (TA), R ¹ has 1 to 20 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 8 carbon atoms, More preferably, it is an alkyl group having 1 or more carbon atoms and 4 or less carbon atoms, particularly preferably 1 or 2 carbon atoms, and an alkyltrialkoxysilane in which R ² is an alkyl group having 1 or more carbon atoms and 2 or less carbon atoms is more preferable.

More specifically, the silane coupling agent constituting the coating structure on the surface of the silica base particles is preferably at least one trifunctional silane coupling agent selected from the group consisting of alkyltrimethoxysilanes and alkyltriethoxysilanes, each of which has an alkyl group with 1 to 20 carbon atoms;
More preferred is at least one trifunctional silane coupling agent selected from the group consisting of alkyltrimethoxysilanes and alkyltriethoxysilanes, each of which has an alkyl group with 1 to 15 carbon atoms;
More preferred is at least one trifunctional silane coupling agent selected from the group consisting of alkyltrimethoxysilanes and alkyltriethoxysilanes, each of which has an alkyl group with 1 to 8 carbon atoms;
More preferred is at least one trifunctional silane coupling agent selected from the group consisting of alkyltrimethoxysilanes and alkyltriethoxysilanes, each of which has an alkyl group with 1 to 4 carbon atoms;
At least one trifunctional silane coupling agent selected from the group consisting of methyltrimethoxysilane, ethyltrimethoxysilane, methyltriethoxysilane, and ethyltriethoxysilane is particularly preferred.

The coating structure composed of the reaction product of the silane coupling agent is preferably 5.5% by mass or more and 30% by mass or less, more preferably 7% by mass or more and 22% by mass or less, based on the entire silica particle (A). .

- Molybdenum nitrogen-containing compounds -
The molybdenum nitrogen-containing compound is a nitrogen-containing compound containing molybdenum, excluding ammonia and compounds that are in a gaseous state at a temperature of 25° C. or less.

The molybdenum nitrogen-containing compound is preferably attached to the pores of the reaction product of the silane coupling agent. The number of molybdenum nitrogen-containing compounds may be one or two or more.

From the viewpoints of narrowing the charge distribution and maintaining the charge distribution, and of allowing the charge to leak appropriately, the molybdenum nitrogen-containing compound is preferably at least one selected from the group consisting of quaternary ammonium salts containing molybdenum element (particularly quaternary ammonium molybdate salts) and mixtures of quaternary ammonium salts and metal oxides containing molybdenum element. Quaternary ammonium salts containing molybdenum element have a strong bond between an anion containing molybdenum element and a quaternary ammonium cation, and therefore have high charge distribution maintenance.

As the molybdenum nitrogen-containing compound, a compound represented by the following formula (1) is preferable.

In formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, and X ⁻ represents an anion containing a molybdenum element. However, at least one of R ¹ , R ² , R ³ and R ⁴ represents an alkyl group, an aralkyl group or an aryl group. Two or more of R ¹ , R ² , R ³ and R ⁴ may be linked to form an aliphatic ring, an aromatic ring or a heterocycle. Here, the alkyl group, aralkyl group and aryl group may have a substituent.

Examples of the alkyl group represented by R ¹ to R ⁴ include a linear alkyl group having from 1 to 20 carbon atoms, and a branched alkyl group having from 3 to 20 carbon atoms. Examples of the linear alkyl group having from 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, and the like. Examples of branched alkyl groups having 3 to 20 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, and a tert-decyl group.
The alkyl group represented by R ¹ to R ⁴ is preferably an alkyl group having 1 to 15 carbon atoms, such as a methyl group, an ethyl group, a butyl group, or a tetradecyl group.

Examples of the aralkyl group represented by R ¹ to R ⁴ include aralkyl groups having 7 or more and 30 or less carbon atoms. Examples of the aralkyl group having 7 to 30 carbon atoms include benzyl group, phenylethyl group, phenylpropyl group, 4-phenylbutyl group, phenylpentyl group, phenylhexyl group, phenylheptyl group, phenyloctyl group, and phenylnonyl group. , naphthylmethyl group, naphthylethyl group, anthrathylmethyl group, phenyl-cyclopentylmethyl group, and the like.
The aralkyl group represented by R ¹ to R ⁴ is preferably an aralkyl group having 7 to 15 carbon atoms such as benzyl group, phenylethyl group, phenylpropyl group, and 4-phenylbutyl group.

The aryl group represented by R ¹ to R ⁴ includes an aryl group having 6 to 20 carbon atoms. Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group, a pyridyl group, and a naphthyl group.
The aryl group represented by R ¹ to R ⁴ is preferably an aryl group having 6 to 10 carbon atoms, such as a phenyl group.

Examples of the ring formed by combining two or more of R ¹ , R ² , R ³ and R ⁴ with each other include an alicyclic ring having 2 to 20 carbon atoms and a heterocyclic amine having 2 to 20 carbon atoms.

R ¹ , R ² , R ³ and R ⁴ may each independently have a substituent. Examples of the substituent include a nitrile group, a carbonyl group, an ether group, an amide group, a siloxane group, a silyl group, and a silane alkoxy group.

R ¹ , R ² , R ³ and R ⁴ each independently represent an alkyl group having 1 to 16 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. preferable.

The anion containing molybdenum element represented by ^X- is preferably a molybdate ion, more preferably a molybdate ion in which molybdenum is tetravalent or hexavalent, and _more preferably _a molybdate ion in which _molybdenum ^{is hexavalent} . Specific _examples of the molybdate ion include _{MoO42- ,} ^Mo2O72- _, ^{Mo3O102-, Mo4O132-} _{, Mo7O242-} ^, _{and Mo8O264-} ^.

From the viewpoints of narrowing the charge distribution and maintaining the charge distribution, and from the viewpoint of allowing the charge to leak appropriately, the compound represented by formula (1) preferably has a total carbon number of 18 to 35, and more preferably has a total carbon number of 20 to 32.

Examples of the compound represented by formula (1) are shown below. This embodiment is not limited to this.

Quaternary ammonium salts containing molybdenum element include [N ⁺ (CH) ₃ (C ₁₄ C ₂₉ ) ₂ ] ₄ Mo ₈ O ₂₈ ^4- , [N ⁺ (C ₄ H ₉ ) ₂ (C ₆ H ₆ ) ₂ ] ₂ Mo ₂ O ₇ ^2- , [N ⁺ (CH ₃ ) ₂ (CH ₂ C ₆ H ₆ ) (CH ₂ ) ₁₇ CH ₃ ] ₂ MoO ₄ ^2- , [N ⁺ (CH ₃ ) ₂ (CH Examples include quaternary ammonium salts of molybdic acid such as ₂ C ₆ H ₆ )(CH ₂ ) ₁₅ CH ₃ ] ₂ MoO ₄ ^2- .

Examples _of metal oxides containing molybdenum include molybdenum oxides (molybdenum trioxide, molybdenum dioxide, _Mo9O26 ), alkali metal molybdates (lithium molybdate, sodium molybdate, potassium molybdate, etc.), alkaline earth metal molybdates (magnesium molybdate, calcium _molybdate , etc. ₎ , and other composite oxides ( _Bi2O3.2MoO3 , γ _{- Ce2Mo3O13 ,} etc.).

When the silica particles (A) are heated at a temperature range of 300°C to 600°C, a molybdenum nitrogen-containing compound is detected. The molybdenum nitrogen-containing compound can be detected by heating at 300°C to 600°C in an inert gas, for example, by using a heating furnace type drop-type pyrolysis gas chromatograph mass spectrometer using He as a carrier gas. Specifically, 0.1 mg to 10 mg of silica particles are introduced into a pyrolysis gas chromatograph mass spectrometer, and the presence or absence of the molybdenum nitrogen-containing compound is confirmed from the MS spectrum of the detected peak. Examples of components generated by pyrolysis from silica particles containing a molybdenum nitrogen-containing compound include primary, secondary, or tertiary amines or aromatic nitrogen compounds represented by the following formula (2). R ¹ , R ² , and R ³ in formula (2) are respectively synonymous with R ¹ , R ² , and R ³ in formula (1). When the molybdenum nitrogen-containing compound is a quaternary ammonium salt, part of the side chain is eliminated by thermal decomposition at 600° C., and a tertiary amine is detected.

-Nitrogen-containing compounds that do not contain molybdenum-
In silica particle (A), the pores of the reaction product of silane coupling agent may have a nitrogen-containing compound that does not contain molybdenum attached thereto.The nitrogen-containing compound that does not contain molybdenum can be, for example, at least one selected from the group consisting of quaternary ammonium salt, primary amine compound, secondary amine compound, tertiary amine compound, amide compound, imine compound and nitrile compound.The nitrogen-containing compound that does not contain molybdenum is preferably a quaternary ammonium salt.

Specific examples of primary amine compounds include phenethylamine, toluidine, catecholamine, and 2,4,6-trimethylaniline.
Specific examples of secondary amine compounds include dibenzylamine, 2-nitrodiphenylamine, and 4-(2-octylamino)diphenylamine.
Specific examples of the tertiary amine compound include 1,8-bis(dimethylamino)naphthalene, N,N-dibenzyl-2-aminoethanol, and N-benzyl-N-methylethanolamine.
Specific examples of amide compounds include N-cyclohexyl-p-toluenesulfonamide, 4-acetamido-1-benzylpiperidine, N-hydroxy-3-[1-(phenylthio)methyl-1H-1,2,3-triazole -4-yl]benzamide.
Specific examples of imine compounds include diphenylmethanimine, 2,3-bis(2,6-diisopropylphenylimino)butane, N,N'-(ethane-1,2-diylidene)bis(2,4,6-trimethyl aniline).
Specific examples of the nitrile compound include 3-indoleacetonitrile, 4-[(4-chloro-2-pyrimidinyl)amino]benzonitrile, and 4-bromo-2,2-diphenylbutyronitrile.

Quaternary ammonium salts include compounds represented by the following formula (AM). The compounds represented by formula (AM) may be one type or two or more types.

In formula (AM), R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, and Z ⁻ represents an anion. However, at least one of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ represents an alkyl group, an aralkyl group or an aryl group. Two or more of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be linked to form an aliphatic ring, an aromatic ring or a heterocycle. Here, the alkyl group, aralkyl group and aryl group may have a substituent.

Examples of the alkyl group represented by R ¹¹ to R ¹⁴ include a linear alkyl group having 1 to 20 carbon atoms and a branched alkyl group having 3 to 20 carbon atoms. Examples of linear alkyl groups having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-heptyl group, -octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group and the like. Examples of branched alkyl groups having 3 to 20 carbon atoms include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group. group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec -decyl group, tert-decyl group, etc.
The alkyl group represented by R ¹¹ to R ¹⁴ is preferably an alkyl group having 1 or more and 15 or less carbon atoms, such as a methyl group, ethyl group, butyl group, or tetradecyl group.

Examples of the aralkyl group represented by R ¹¹ to R ¹⁴ include aralkyl groups having 7 to 30 carbon atoms. Examples of the aralkyl group having 7 to 30 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group,
Examples of the alkyl group include a naphthylmethyl group, a naphthylethyl group, an anthrathymethyl group, and a phenyl-cyclopentylmethyl group.
The aralkyl group represented by R ¹¹ to R ¹⁴ is preferably an aralkyl group having 7 to 15 carbon atoms, such as a benzyl group, a phenylethyl group, a phenylpropyl group, or a 4-phenylbutyl group.

The aryl group represented by R ¹¹ to R ¹⁴ includes an aryl group having from 6 to 20 carbon atoms. Examples of the aryl group having from 6 to 20 carbon atoms include a phenyl group, a pyridyl group, and a naphthyl group.
The aryl group represented by R ¹¹ to R ¹⁴ is preferably an aryl group having 6 to 10 carbon atoms, such as a phenyl group.

The ring formed by connecting two or more of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ to each other includes an alicyclic ring having 2 to 20 carbon atoms, a heterocyclic amine having 2 to 20 carbon atoms, etc. Can be mentioned.

R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may each independently have a substituent. Examples of the substituent include a nitrile group, a carbonyl group, an ether group, an amide group, a siloxane group, a silyl group, and a silane alkoxy group.

R ¹¹ , R ¹² , R ¹³ and R ¹⁴ can each independently represent an alkyl group having 1 to 16 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. preferable.

The anion represented by Z ^{1 -} may be either an organic anion or an inorganic anion.
Examples of the organic anion include a polyfluoroalkylsulfonate ion, a polyfluoroalkylcarboxylate ion, a tetraphenylborate ion, an aromatic carboxylate ion, and an aromatic sulfonate ion (eg, 1-naphthol-4-sulfonate ion).
Examples of inorganic anions include OH ⁻ , F ⁻ , Fe(CN) ₆ ³⁻ , Cl ⁻ , Br ⁻ , NO ₂ ⁻ , NO ₃ ⁻ , CO ₃ ²⁻ , PO ₄ ³⁻ , and SO ₄ ²⁻ .

From the viewpoints of narrowing the charge distribution and maintaining the charge distribution, and from the viewpoint of allowing the charge to leak appropriately, the compound represented by formula (AM) preferably has a total carbon number of 18 to 35, and more preferably has a total carbon number of 20 to 32.

Examples of compounds represented by formula (AM) are shown below. The present embodiment is not limited to these.

The total content of the molybdenum nitrogen-containing compound and the nitrogen element-containing compound not containing molybdenum contained in the silica particles (A) is determined from the viewpoints of narrowing the charge distribution and maintaining the charge distribution, and from the viewpoint of leaking charge appropriately. , the mass ratio N/Si of nitrogen element to silicon element is preferably 0.005 or more and 0.50 or less, more preferably 0.008 or more and 0.45 or less, more preferably 0.015 or more and 0.20 or less, and 0. More preferably .018 or more and 0.10 or less.

The above mass ratio N/Si in the silica particles (A) is determined by measuring the mass ratio of N atoms to Si atoms using an oxygen/nitrogen analyzer (for example, EMGA-920 manufactured by Horiba, Ltd.) for an integrated time of 45 seconds. Find it as (N/Si). The sample is pretreated by vacuum drying at 100° C. for 24 hours or more to remove impurities such as ammonia.

The total extraction amount X of the molybdenum nitrogen-containing compound and the nitrogen-containing compound not containing molybdenum element extracted from the silica particles (A) by the ammonia/methanol mixed solution is preferably 0.1 mass% or more relative to the mass of the silica particles (A). And, the total extraction amount X of the molybdenum nitrogen-containing compound and the nitrogen-containing compound not containing molybdenum element extracted from the silica particles (A) by the ammonia/methanol mixed solution and the total extraction amount Y of the molybdenum nitrogen-containing compound and the nitrogen-containing compound not containing molybdenum element extracted from the silica particles (A) by water (similar to X, the mass ratio to the mass of the silica particles (A)) preferably satisfies Y/X<0.3.
The above relationship indicates that the nitrogen-containing compound contained in silica particles (A) is difficult to dissolve in water, that is, difficult to adsorb moisture in air.Therefore, the above relationship makes silica particles (A) excellent in narrowing charge distribution and maintaining charge distribution.In addition, the above relationship makes silica particles (A) less susceptible to the influence of moisture in air and excellent in the effect of leaking charge appropriately.

The extraction amount X is preferably 0.25% by mass or more and 6.5% by mass or less relative to the mass of the silica particles (A). The ratio Y/X of the extraction amount X to the extraction amount Y is ideally 0.

The extraction amount X and the extraction amount Y are measured by the following method.
Silica particles are analyzed at 400°C using a thermogravimetric/mass spectrometer (e.g., a gas chromatograph mass spectrometer manufactured by Netch Japan Co., Ltd.), and the silica particles are a compound in which a hydrocarbon having one or more carbon atoms is covalently bonded to a nitrogen atom. The mass fraction is measured and integrated to obtain W1.
1 part by mass of silica particles was added to 30 parts by mass of an ammonia/methanol solution (manufactured by Sigma-Aldrich, mass ratio of ammonia/methanol = 1/5.2) at a liquid temperature of 25°C, and ultrasonication was performed for 30 minutes. After that, the silica powder and the extract liquid are separated. The separated silica particles were dried at 100°C for 24 hours in a vacuum dryer, and the mass fraction of the compound in which a hydrocarbon with a carbon number of 1 or more is covalently bonded to a nitrogen atom was determined with respect to the silica particles at 400°C using a thermogravimetric/mass spectrometer. Measure and integrate it to obtain W2.
1 part by mass of silica particles is added to 30 parts by mass of water at a liquid temperature of 25° C., and after ultrasonication is performed for 30 minutes, the silica particles and the extract are separated. The separated silica particles were dried at 100°C for 24 hours in a vacuum dryer, and the mass fraction of the compound in which a hydrocarbon with a carbon number of 1 or more is covalently bonded to a nitrogen atom was determined with respect to the silica particles at 400°C using a thermogravimetric/mass spectrometer. Measure and integrate it to obtain W3.
From W1 and W2, the extraction amount X=W1-W2 is calculated.
From W1 and W3, the extraction amount Y=W1-W3 is calculated.

-Hydrophobized structure-
In the silica particles (A), a hydrophobized structure (a structure obtained by treating silica particles with a hydrophobization treatment agent) may be attached to the coating structure of the reaction product of the silane coupling agent.

As the hydrophobizing agent, for example, an organosilicon compound is applied. Examples of organosilicon compounds include the following.
Alkoxysilane compounds or halosilane compounds having a lower alkyl group such as methyltrimethoxysilane, dimethyldimethoxysilane, trimethylchlorosilane, and trimethylmethoxysilane.
Alkoxysilane compounds having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane.
2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycid Alkoxysilane compounds having epoxy groups such as oxypropyltriethoxysilane.
Alkoxysilane compounds having a styryl group such as p-styryltrimethoxysilane and p-styryltriethoxysilane.
N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, Alkoxysilane compounds having an aminoalkyl group such as 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine and N-phenyl-3-aminopropyltrimethoxysilane.
Alkoxysilane compounds having an isocyanate alkyl group such as 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane.
Silazane compounds such as hexamethyldisilazane and tetramethyldisilazane.

From the viewpoints of narrowing the charge distribution and maintaining the charge distribution, and of dispersing with high uniformity on the toner particle surface, it is preferable that the silica particles (A) have the following characteristics.

- Average circularity, average primary particle size, number particle size distribution index -
The average circularity of the silica particles (A) is preferably from 0.60 to 0.96, more preferably from 0.65 to 0.94, still more preferably from 0.70 to 0.92, and still more preferably from 0.75 to 0.90.

It is preferable that the silica particles (A) are monodisperse particles having one peak in a circularity region of more than 0.88 in the circularity distribution of the primary particles.

The average primary particle size of the silica particles (A) is preferably 10 nm or more and 120 nm or less, more preferably 20 nm or more and 100 nm or less, even more preferably 30 nm or more and 90 nm or less, and particularly preferably 40 nm or more and 80 nm or less.

The number particle size distribution index of the silica particles (A) is preferably 1.1 or more and 2.0 or less, more preferably 1.15 or more and 1.6 or less.

The average circularity, average primary particle size, and number particle size distribution index of the silica particles (A) are measured by the following methods.
The toner is photographed at a magnification of 40,000 times using a scanning electron microscope (SEM) (S-4800, manufactured by Hitachi High-Technologies) equipped with an energy dispersive X-ray analyzer (EDX device) (EMAX Evolution X-Max ⁸⁰ mm 2, manufactured by Horiba, Ltd.). 200 silica particles (A) are identified from one visual field based on the presence of Mo, N and Si elements by EDX analysis. The images of the 200 silica particles (A) are analyzed using image processing analysis software WinRoof (Mitani Shoji Co., Ltd.). The circle-equivalent diameter, area and perimeter of each primary particle image are obtained, and the circularity = 4π × (area of particle image) ÷ (perimeter of particle image) ² is obtained. The circularity at which the cumulative 50% from the small side in the distribution of circularity is defined as the average circularity. The circle-equivalent diameter at which the cumulative 50% from the small diameter side in the distribution of circle-equivalent diameters is defined as the average primary particle size. The particle size at 16% cumulative from the small diameter side in the distribution of equivalent circle diameters is defined as D16, and the particle size at 84% cumulative from the small diameter side is defined as D84, and the number particle size distribution index = (D84/D16) ^0.5 is calculated.

- Hydrophobicity -
The hydrophobicity of the silica particles (A) is preferably from 10% to 60%, more preferably from 20% to 55%, and even more preferably from 28% to 53%.
When the hydrophobicity of the silica particles (A) is 10% or more, the silica particles (A) are unlikely to be embedded in the toner particles, and charge is likely to leak appropriately, thereby preventing the toner from being excessively negatively charged.
When the hydrophobicity of the silica particles (A) is 60% or less, it is believed that the charge leaks appropriately, and the toner is prevented from being excessively negatively charged.

The method for measuring the hydrophobicity of the silica particles is as follows.
0.2% by mass of silica particles are placed in 50 ml of ion-exchanged water, and methanol is dropped from a burette while stirring with a magnetic stirrer. The mass fraction of methanol in the methanol-water mixed solution at the end point when the entire sample has sunk is determined as the degree of hydrophobicity.

-Volume resistivity-
The volume resistivity R of the silica particles (A) is preferably 1.0×10 ⁷ Ωcm or more and 1.0×10 ^12.5 Ωcm or less, more preferably 1.0×10 ^7.5 Ωcm or more and 1.0×10 ¹² Ωcm or less, more preferably 1.0×10 ⁸ Ωcm or more and 1.0×10 ^11.5 Ωcm or less, and even more preferably 1.0×10 ⁹ Ω·cm or more and 1.0×10 ¹¹ Ω·cm or less. The volume resistivity R of the silica particles (A) can be adjusted by the content of the molybdenum nitrogen-containing compound.

When the volume resistivities of the silica particles (A) before and after firing at 350° C. are Ra and Rb, respectively, the ratio Ra/Rb is preferably 0.01 to 0.8, more preferably 0.015 to 0.6.
The volume resistivity Ra (same as the volume resistivity R) of the silica particles (A) before firing at 350°C is preferably 1.0 x 10 ⁷ Ωcm or more and 1.0 x 10 ^12.5 Ωcm or less, more preferably 1.0 x 10 ^7.5 Ωcm or more and 1.0 x 10 ¹² Ωcm or less, more preferably 1.0 x 10 ⁸ Ωcm or more and 1.0 x 10 ^11.5 Ωcm or less, and even more preferably 1.0 x 10 ⁹ Ω·cm or more and 1.0 x 10 ¹¹ Ω·cm or less.

The 350° C. firing is performed by increasing the temperature to 350° C. at a rate of 10° C./min in a nitrogen environment, holding the temperature at 350° C. for 3 hours, and then cooling to room temperature (25° C.) at a rate of 10° C./min.
The volume resistivity of the silica particles (A) is measured in an environment at a temperature of 20° C. and a relative humidity of 50% as described below.
Silica particles (A) are placed on the surface of a circular jig with a ²⁰ cm2 electrode plate to a thickness of about 1 mm to 3 mm to form a silica particle layer. A ²⁰ cm2 electrode plate is placed on the silica particle layer to sandwich the silica particle layer, and a pressure of 0.4 MPa is applied to the electrode plate to eliminate gaps between the silica particles. The thickness L (cm) of the silica particle layer is measured. An impedance analyzer (manufactured by Solartron Analytical Co., Ltd.) connected to both the upper and lower electrodes of the silica particle layer is used to obtain a Nyquist plot in the frequency range of 10 ^-3 Hz to 10 ⁶ Hz. This is fitted to an equivalent circuit, assuming that there are three types of resistance components, namely bulk resistance, particle interface resistance, and electrode contact resistance, to determine the bulk resistance R (Ω). From the bulk resistance R (Ω) and the thickness L (cm) of the silica particle layer, the volume resistivity ρ (Ω·cm) of the silica particles is calculated by the formula ρ=R/L.

-OH group amount-
The amount of OH groups in the silica particles (A) is preferably 0.05 to 6/nm ² , more preferably 0.1 to ^{5.5/nm 2 ,} and more preferably 0.1 to 5.5/nm ² . 15 pieces/nm ² or more and 5 pieces/nm ² or less are preferable, 0.2 pieces/nm ² or more and 4 pieces/nm ² or less are more preferable, and 0.2 pieces/nm ² or more and 3 pieces/nm ² or less are still more preferable. .

The amount of OH groups in the silica particles is measured by the Sears method as follows.
Add 1.5 g of silica particles to a 50 g water/50 g ethanol mixture and stir with an ultrasonic homogenizer for 2 minutes to prepare a dispersion. While stirring in an environment of 25°C, drop 1.0 g of 0.1 mol/L hydrochloric acid aqueous solution to obtain a test solution. Put the test solution into an automatic titration device, perform potentiometric titration with 0.01 mol/L sodium hydroxide aqueous solution, and create a differential curve of the titration curve. Among the inflection points where the differential value of the titration curve is 1.8 or more, the titration amount where the titration amount of 0.01 mol/L sodium hydroxide aqueous solution is the largest is designated as E.
The surface silanol group density ρ (pieces/nm ² ) of the silica particles is calculated from the following formula, and this is regarded as the amount of OH groups of the silica particles.
Formula: ρ=((0.01×E−0.1)×NA/1000)/(M×S _BET ×10 ¹⁸ )
E: the titration amount of 0.01 mol/L sodium hydroxide aqueous solution that is the largest among the inflection points where the differential value of the titration curve is 1.8 or more, NA: Avogadro's number, M: amount of silica particles (1.5 g), S _BET : BET specific surface area (m ² /g) of silica particles measured by nitrogen adsorption three-point method (equilibrium relative pressure is 0.3).

-Pore diameter-
Silica particles (A) have a first peak in a pore diameter range of 0.01 nm or more and 2 nm or less, and a second peak in a pore diameter range of 1.5 nm or more and 50 nm or less in a pore distribution curve of the nitrogen gas adsorption method. It is preferable to have two peaks, more preferably to have a second peak in a range of 2 nm to 50 nm, even more preferably to have a second peak in a range of 2 nm to 40 nm, and a second peak in a range of 2 nm to 30 nm. It is more preferable to have two peaks.
When the first peak and the second peak are within the above range, the molybdenum nitrogen-containing compound penetrates deep into the pores of the coating structure, narrowing the charge distribution, and leaking charge appropriately.

The method for determining the pore distribution curve using the nitrogen gas adsorption method is as follows.
The silica particles are cooled to liquid nitrogen temperature (-196° C.), nitrogen gas is introduced, and the amount of nitrogen gas adsorbed is determined by a constant volume method or a gravimetric method. An adsorption isotherm is created by gradually increasing the pressure of introduced nitrogen gas and plotting the amount of nitrogen gas adsorbed for each equilibrium pressure. From the adsorption isotherm, a pore size distribution curve in which the vertical axis represents the frequency and the horizontal axis represents the pore diameter is determined using the calculation formula of the BJH method. From the obtained pore size distribution curve, an integrated pore volume distribution in which the vertical axis represents the volume and the horizontal axis represents the pore diameter is determined, and the position of the peak of the pore diameter is confirmed.

From the viewpoints of narrowing the charge distribution and maintaining the charge distribution, and of allowing the charge to leak appropriately, it is preferable that the silica particles (A) satisfy either of the following characteristics (A) and (B).

・Aspect (A): When the pore volumes with pore diameters of 1 nm or more and 50 nm or less obtained from the pore distribution curve of the nitrogen gas adsorption method before and after firing at 350°C are respectively A and B, the ratio B/A is 1.2 5 or less, and B is 0.2 cm ³ /g or more and 3 cm ³ /g or less.
Hereinafter, "the pore volume A with a pore diameter of 1 nm or more and 50 nm or less obtained from the pore distribution curve of the nitrogen gas adsorption method before firing at 350°C" is referred to as "pore volume A before firing at 350°C", and "pore volume A before firing at 350°C" The pore volume B with a pore diameter of 1 nm or more and 50 nm or less determined from the pore distribution curve of the nitrogen gas adsorption method after firing is referred to as the ``pore volume B after firing at 350°C''.

In the 350°C firing, the temperature is raised to 350°C at a temperature increase rate of 10°C/min in a nitrogen environment, held at 350°C for 3 hours, and cooled to room temperature (25°C) at a temperature increase rate of 10°C/min.
The method for measuring pore volume is as follows.
Silica particles are cooled to liquid nitrogen temperature (-196° C.), nitrogen gas is introduced, and the amount of nitrogen gas adsorbed is determined by a constant volume method or a gravimetric method. An adsorption isotherm is created by gradually increasing the pressure of introduced nitrogen gas and plotting the amount of nitrogen gas adsorbed for each equilibrium pressure. From the adsorption isotherm, a pore size distribution curve is determined using the calculation formula of the BJH method, with the vertical axis representing the frequency and the horizontal axis representing the pore diameter. From the obtained pore size distribution curve, an integrated pore volume distribution is determined, with the vertical axis representing the volume and the horizontal axis representing the pore diameter. From the obtained integrated pore volume distribution, the pore volume in the range of pore diameters of 1 nm to 50 nm is integrated, and this is defined as "pore volume of pore diameters of 1 nm to 50 nm".

The ratio B/A of the pore volume A before firing at 350° C. to the pore volume B after firing at 350° C. is preferably 1.2 or more and 5 or less, more preferably 1.4 or more and 3 or less, and even more preferably 1.4 or more and 2.5 or less.
The pore volume B after firing at 350° C. is preferably 0.2 cm ³ /g to 3 cm ³ /g, more preferably 0.3 cm ³ /g to 1.8 cm ³ /g, and even more preferably 0.6 cm ³ /g to 1.5 cm ³ /g.

In embodiment (A), a sufficient amount of a nitrogen-containing compound is adsorbed in at least some of the pores of the silica particles.

Aspect (B): A cross polarization/magic angle spinning (CP/MAS) ^29Si solid-state nuclear magnetic resonance (NMR) spectrum (hereinafter referred to as "Si-CP/MAS NMR spectrum"), in which the ratio C/D of an integral value C of a signal observed in a chemical shift range of -50 ppm or more and -75 ppm or less to an integral value D of a signal observed in a chemical shift range of -90 ppm or more and -120 ppm or less is 0.10 or more and 0.75 or less.

The Si-CP/MAS NMR spectrum is obtained by carrying out nuclear magnetic resonance spectroscopy under the following conditions.
Spectrometer: AVENCE 300 (manufactured by Brunker)
Resonance frequency: 59.6MHz
Measurement nucleus: ^29Si
Measurement method: CPMAS method (using Bruker's standard Palksequence cp.av)
Waiting time: 4 seconds Contact time: 8 milliseconds Number of measurements: 2048 Measurement temperature: Room temperature (actual measurement value 25°C)
・Center frequency: -3975.72Hz
・MAS rotation speed: 7.0 mm-6 kHz
・Reference substance: Hexymethylcyclotrisiloxane

The ratio C/D is preferably 0.10 or more and 0.75 or less, more preferably 0.12 or more and 0.45 or less, and even more preferably 0.15 or more and 0.40 or less.

When the integral value of all signals in the Si-CP/MAS NMR spectrum is taken as 100%, the ratio (Signal ratio) of the integral value C of the signals observed in the chemical shift range of -50 ppm to -75 ppm is 5% or more. is preferable, and 7% or more is more preferable. The upper limit of the ratio of the signal integral value C is, for example, 60% or less.

The embodiment (B) is an embodiment in which at least a part of the silica particle surface has a low-density coating structure capable of adsorbing a sufficient amount of nitrogen-containing compound.This low-density coating structure is, for example, a coating structure made of a reaction product of a silane coupling agent (particularly a trifunctional silane coupling agent), for example, a SiO2 _{/ 3CH3} layer.

[Method for producing silica particles (A)]
An example of the method for producing silica particles (A) includes a first step of forming a coating structure made of a reaction product of a silane coupling agent on at least a part of the surface of a silica mother particle, and a step of forming a coating structure containing molybdenum nitrogen in the coating structure. and a second step of attaching a compound. The present manufacturing method may further include a third step of subjecting the silica mother particles having the coating structure to a hydrophobization treatment after or during the second step. The above steps will be explained in detail below.

-Silica mother particles-
The silica base particles are prepared, for example, by the following step (i) or step (ii).
Step (i) A step of preparing a silica base particle suspension by mixing a solvent containing an alcohol with silica base particles.
Step (ii) A step of granulating the silica base particles by a sol-gel method to obtain a silica base particle suspension.

The silica base particles used in step (i) may be dry silica or wet silica. Specific examples include sol-gel silica, aqueous colloidal silica, alcoholic silica, fused silica, and fused silica.

The alcohol-containing solvent used in step (i) may be a solvent containing only alcohol, or may be a mixed solvent of alcohol and other solvents. Examples of the alcohol include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, and butanol. Examples of other solvents include water; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and acetic acid cellosolve; ethers such as dioxane and tetrahydrofuran; and the like. In the case of a mixed solvent, the proportion of alcohol is preferably 80% by mass or more, more preferably 85% by mass or more.

The step (ii) is preferably a sol-gel method including an alkaline catalyst solution preparation step of preparing an alkaline catalyst solution containing an alkaline catalyst in a solvent containing alcohol, and a silica base particle generation step of supplying tetraalkoxysilane and an alkaline catalyst into the alkaline catalyst solution to generate silica base particles.

The alkaline catalyst solution preparation step is preferably a step of preparing a solvent containing alcohol and mixing this solvent with an alkaline catalyst to obtain an alkaline catalyst solution.

The alcohol-containing solvent may be a solvent containing alcohol alone, or may be a mixed solvent of alcohol and other solvents. Examples of the alcohol include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, and butanol. Examples of other solvents include water; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and acetic acid cellosolve; ethers such as dioxane and tetrahydrofuran; and the like. In the case of a mixed solvent, the proportion of alcohol is preferably 80% by mass or more, more preferably 85% by mass or more.

The alkali catalyst is a catalyst for promoting the reaction (hydrolysis reaction and condensation reaction) of tetraalkoxysilane, and examples thereof include basic catalysts such as ammonia, urea, and monoamine, with ammonia being particularly preferred.

The concentration of the alkaline catalyst in the alkaline catalyst solution is preferably 0.5 mol/L or more and 1.5 mol/L or less, more preferably 0.6 mol/L or more and 1.2 mol/L or less, and even more preferably 0.65 mol/L or more and 1.1 mol/L or less.

In the silica base particle generation step, a tetraalkoxysilane and an alkali catalyst are respectively supplied into an alkaline catalyst solution, and the tetraalkoxysilane is reacted (hydrolysis reaction and condensation reaction) in the alkaline catalyst solution to generate silica base particles. This is the process of

In the silica base particle generation process, after core particles are generated by the reaction of tetraalkoxysilane at the initial stage of supply of tetraalkoxysilane (nucleus particle generation stage), this core particle grows (core particle growth stage), and then silica base particles is generated.

Examples of the tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. Tetramethoxysilane or tetraethoxysilane is preferred from the viewpoint of controllability of the reaction rate or uniformity of the shape of the silica mother particles produced.

Examples of the alkali catalyst to be supplied to the alkali catalyst solution include basic catalysts such as ammonia, urea, and monoamines, with ammonia being particularly preferred. The alkali catalyst supplied together with the tetraalkoxysilane may be of the same type as the alkali catalyst pre-contained in the alkali catalyst solution, or may be of a different type, but it is of the same type. It is preferable.

The feeding method for respectively feeding the tetraalkoxysilane and the alkali catalyst into the alkaline catalyst solution may be a continuous feeding method or an intermittent feeding method.

In the silica mother particle generation step, the temperature of the alkali catalyst solution (temperature at the time of supply) is preferably 5°C or more and 50°C or less, more preferably 15°C or more and 45°C or less.

-First process-
The first step is, for example, a step of adding a silane coupling agent to a suspension of silica base particles and reacting the silane coupling agent on the surfaces of the silica base particles to form a coating structure made of a reaction product of the silane coupling agent.

The reaction of the silane coupling agent is carried out, for example, by adding the silane coupling agent to a silica base particle suspension and then heating the suspension while stirring. Specifically, for example, the suspension is heated to 40°C to 70°C, and the silane coupling agent is added and stirred. The stirring time is preferably 10 minutes to 24 hours, more preferably 60 minutes to 420 minutes, and even more preferably 80 minutes to 300 minutes.

-Second process-
The second step is preferably a step of attaching a molybdenum nitrogen-containing compound to the pores of the coating structure made of the reaction product of the silane coupling agent.

In the second step, for example, a molybdenum nitrogen-containing compound is added to the silica mother particle suspension after reacting with the silane coupling agent, and the mixture is stirred while maintaining the liquid temperature in a temperature range of 20°C or higher and 50°C or lower. . Here, the molybdenum nitrogen-containing compound may be added to the silica particle suspension as an alcoholic solution containing the molybdenum nitrogen-containing compound. The alcohol may be of the same type as the alcohol contained in the silica mother particle suspension, or may be of a different type, but it is more preferable that the alcohol is of the same type. In the alcoholic liquid containing the molybdenum nitrogen-containing compound, the concentration of the molybdenum nitrogen-containing compound is preferably 0.05% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 6% by mass or less.

-Third step-
The third step is a step of further attaching a hydrophobized structure to the coating structure made of the reaction product of the silane coupling agent. The third step is a hydrophobization treatment step performed after or during the second step. In the hydrophobizing agent, the functional groups of the hydrophobizing agent react with each other and/or the functional groups of the hydrophobizing agent react with the OH groups of the silica mother particles to form a hydrophobizing layer.

In the third step, for example, a molybdenum nitrogen-containing compound is added to the silica base particle suspension after the reaction of the silane coupling agent, and then a hydrophobic treatment agent is added. At this time, it is preferable to stir and heat the suspension. For example, the suspension is heated to 40°C to 70°C, the hydrophobic treatment agent is added, and the mixture is stirred. The stirring time is preferably 10 minutes to 24 hours, more preferably 20 minutes to 120 minutes, and even more preferably 20 minutes to 90 minutes.

-Drying process-
After performing the second step or the third step, or during the implementation of the second step or the third step, it is preferable to implement a drying step of removing the solvent from the suspension. Examples of the drying method include thermal drying, spray drying, and supercritical drying.

Spray drying can be performed by a known method using a spray dryer (rotating disk type, nozzle type, etc.). For example, the silica particle suspension is sprayed into a hot air stream at a rate of 0.2 liter/hour or more and 1 liter/hour or less. The temperature of the hot air is preferably in the range of an inlet temperature of 70°C or more and 400°C or less, and an outlet temperature of 40°C or more and 120°C or less. A more preferable inlet temperature is in the range of 100°C or more and 300°C or less. The silica particle concentration of the silica particle suspension is preferably 10% by mass or more and 30% by mass or less.

Examples of substances used as supercritical fluids for supercritical drying include carbon dioxide, water, methanol, ethanol, and acetone. As the supercritical fluid, supercritical carbon dioxide is preferable from the viewpoint of treatment efficiency and from the viewpoint of suppressing the generation of coarse particles. Specifically, the step using supercritical carbon dioxide is performed, for example, by the following operation.

After storing the suspension in a closed reactor and then introducing liquefied carbon dioxide, the closed reactor is heated and the pressure inside the closed reactor is increased using a high-pressure pump to bring the carbon dioxide in the closed reactor to a supercritical state. do. Then, by flowing liquefied carbon dioxide into the closed reactor and letting supercritical carbon dioxide flow out from the closed reactor, supercritical carbon dioxide is made to flow through the suspension in the closed reactor. While the supercritical carbon dioxide is flowing through the suspension, the solvent is dissolved in the supercritical carbon dioxide, and the solvent is removed along with the supercritical carbon dioxide flowing out of the closed reactor. The temperature and pressure in the closed reactor are such that the carbon dioxide becomes supercritical. Where the critical point of carbon dioxide is 31.1° C./7.38 MPa, the temperature and pressure are, for example, 40° C. or higher and 200° C. or higher/pressure 10 MPa or higher and 30 MPa or lower. The flow rate of the supercritical fluid to the closed reactor is preferably 80 mL/sec or more and 240 mL/sec or less.

The obtained silica particles are preferably crushed or sieved to remove coarse particles and aggregates. The crushing is performed using a dry crushing device such as a jet mill, a vibration mill, a ball mill, or a pin mill. The sieving is performed using, for example, a vibrating sieve, a wind sieve, or the like.

[Inorganic particles (B)]
The average primary particle size of the inorganic particles (B) as a whole is from 10 to 80 nm, preferably from 15 to 65 nm, and more preferably from 25 to 60 nm, from the viewpoint of covering the toner particle surfaces with high uniformity.

It is preferable that the inorganic particles (B) have at least one peak in the circularity distribution of the primary particles in a region of circularity of 0.88 or less.

The average primary particle diameter and circularity distribution of the inorganic particles (B) are determined as follows.
Using a scanning electron microscope (SEM) (manufactured by Hitachi High-Technologies, S- ⁴⁸⁰⁰ ) equipped with an energy dispersive X-ray analyzer (EDX device) (manufactured by Horiba, Ltd., EMAX Evolution Photograph the toner at double magnification. Based on the presence of Mo element, N element, and Si element, silica particles (A) are excluded by EDX analysis, and 200 inorganic particles (B) other than silica particles (A) are identified from within one field of view. Images of 200 inorganic particles (B) are analyzed using image processing analysis software WinRoof (Mitani Shoji Co., Ltd.). The equivalent circle diameter, area, and perimeter of each primary particle image are determined. In the distribution of equivalent circle diameters, the equivalent circle diameter that is cumulatively 50% from the small diameter side is defined as the average primary particle diameter. The circularity is circularity=4π×(area of particle image)÷(perimeter of particle image) ² .

The volume resistivity of the entire inorganic particles (B) is preferably 1.0×10 ¹⁴ Ω·cm or more, 1.0×10 ¹⁷ Ω·cm or more, and 1.0× More preferably, it is 10 ¹⁴ Ω·cm or more and 1.0×10 ¹⁶ Ω·cm or less.

The volume resistivity of the inorganic particles (B) is measured in an environment at a temperature of 20° C. and a relative humidity of 50% as described below.
On the surface of a circular jig with a ²⁰ cm2 electrode plate, inorganic particles (B) are placed to a thickness of about 1 mm to 3 mm to form an inorganic particle layer. A ²⁰ cm2 electrode plate is placed on the inorganic particle layer to sandwich the inorganic particle layer, and a pressure of 0.4 MPa is applied to the electrode plate to eliminate gaps between the inorganic particles. The thickness L (cm) of the inorganic particle layer is measured. An impedance analyzer (manufactured by Solartron Analytical Co., Ltd.) connected to both the upper and lower electrodes of the inorganic particle layer is used to obtain a Nyquist plot in the frequency range of 10 ^-3 Hz to 10 ⁶ Hz. This is fitted to an equivalent circuit, assuming that there are three types of resistance components, namely bulk resistance, particle interface resistance, and electrode contact resistance, to determine the bulk resistance R (Ω). From the bulk resistance R (Ω) and the thickness L (cm) of the inorganic particle layer, the volume resistivity ρ (Ω·cm) of the inorganic particles is calculated by the formula ρ = R / L.

The total amount of inorganic particles (B) added externally is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.1 parts by mass or more and 2.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1.5 parts by mass or less, relative to 100 parts by mass of toner particles.

Inorganic particles (B) include SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO.SiO ₂ , K ₂ O.(TiO ₂ ) _n , Al ₂ O 3.2SiO ₂ , CaCO ₃ , MgCO _{3 ,} BaSO ₄ , MgSO ₄ , SrTiO ₃ and the like.

The surfaces of the inorganic particles (B) are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, but examples thereof include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents, silazane compounds, and the like. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is usually, for example, 1 part by mass or more and 10 parts by mass or more per 100 parts by mass of the inorganic particles.

An example of an embodiment of the inorganic particles (B) is silica particles other than the silica particles (A). In this disclosure, silica particles other than the silica particles (A) are referred to as silica particles (B).

The silica particles (B) may contain a nitrogen element-containing compound containing molybdenum element, but in that case, the net intensity N _Mo of molybdenum element and the net intensity N _Si of silicon element measured by X-ray fluorescence analysis The ratio N _Mo /N _Si is less than 0.035 or more than 0.45.
The silica particles (B) are preferably silica particles that do not contain a nitrogen element-containing compound containing molybdenum element.

As the silica particles (B), the surface of silica particles such as sol-gel silica, aqueous colloidal silica, alcoholic silica, made silica, and fused silica may be treated with a hydrophobizing agent (e.g., silane coupling agent, silicone oil, titanate-based Hydrophobic silica particles (B) surface-treated with a coupling agent, an aluminum-based coupling agent, a silazane compound) are preferred. When the silica particles (B) are hydrophobic silica particles (B), the charge distribution of the toner tends to be uniform.

From the viewpoint of coating the toner particle surface with high uniformity, the average primary particle size of the silica particles (B) is preferably 10 nm or more and 80 nm or less, more preferably 15 nm or more and 65 nm or less, and even more preferably 25 nm or more and 60 nm or less.

The silica particles (B) are preferably monodisperse particles having one peak in the circularity distribution of the primary particles in a region of 0.88 or less.

From the viewpoint of optimizing the charged state of the toner, the volume resistivity of the silica particles (B) is preferably from 1.0×10 ¹⁴ Ω·cm to 1.0×10 ¹⁷ Ω·cm, and more preferably from 1.0×10 ¹⁴ Ω·cm to 1.0×10 ¹⁶ Ω·cm.

As an example of an embodiment of the toner according to the present embodiment, the inorganic particles (B) may be only silica particles (B) (preferably only hydrophobic silica particles (B)).
In the above embodiment, the amount of the silica particles (B) (preferably the hydrophobic silica particles (B)) added externally is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.1 parts by mass or more and 2.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1.5 parts by mass or less, relative to 100 parts by mass of the toner particles.

An example of an embodiment of the inorganic particles (B) is titanium compound particles. Examples of the titanium compound particles include titanium oxide particles (compositional formula TiO ₂ ) and titanate particles. The titanate particles include both orthotitanate particles (compositional formula M ₂ TiO ₄ , M is a divalent cation) and metatitanate particles (compositional formula MTiO ₃ , M is a divalent cation).
Titanium oxide particles and titanate particles are hydrophobic titanium compounds surface-treated with a hydrophobic treatment agent (e.g., silane coupling agent, silicone oil, titanate coupling agent, aluminum coupling agent, silazane compound). Preferably they are particles.

From the viewpoint of coating the toner particle surface with high uniformity, the average primary particle size of the titanium compound particles is preferably 10 nm or more and 80 nm or less, more preferably 15 nm or more and 65 nm or less, and even more preferably 25 nm or more and 60 nm or less.

It is preferable that the titanium compound particles have at least one peak in the circularity distribution of the primary particles in a region of circularity of 0.88 or less.

As an example of an embodiment of the toner according to the present exemplary embodiment, the inorganic particles (B) may be titanium compound particles alone.
In the above embodiment, the amount of the titanium compound particles added externally is preferably 0.1 parts by mass to 3.0 parts by mass, more preferably 0.1 parts by mass to 2.0 parts by mass, and even more preferably 0.1 parts by mass to 1.5 parts by mass, based on 100 parts by mass of the toner particles.

As an example of an embodiment of the toner according to the present exemplary embodiment, the inorganic particles (B) may be titanate particles alone.
In the above embodiment, the amount of the titanate particles added externally is preferably 0.1 parts by mass to 3.0 parts by mass, more preferably 0.1 parts by mass to 2.0 parts by mass, and even more preferably 0.1 parts by mass to 1.5 parts by mass, based on 100 parts by mass of the toner particles.

Specific examples of titanate particles include alkaline earth metal titanate particles such as magnesium titanate particles, calcium titanate particles, strontium titanate particles, and barium titanate particles, with strontium titanate particles being preferred.

As the strontium titanate particles, strontium titanate particles doped with a metal element (dopant) other than titanium and strontium are preferable. The strontium titanate particles containing the dopant have a rounded shape and are easily dispersed with high uniformity on the surface of the toner particles. As the strontium titanate particles, strontium titanate particles doped with lanthanum are most preferred.

The dopant of the strontium titanate particles is not particularly limited as long as it is a metal element other than titanium and strontium. One type of dopant may be used alone, or two or more types may be used in combination.
Specifically, dopants for the strontium titanate particles include lanthanides, silica, aluminum, magnesium, calcium, barium, phosphorus, sulfur, calcium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, yttrium, Examples include zinc, niobium, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, antimony, barium, tantalum, tungsten, rhenium, osmium, iridium, platinum, and bismuth. As the lanthanoid, lanthanum and cerium are preferred. Among these, lanthanum is preferred from the viewpoint of easy doping and easy control of the shape of strontium titanate particles.

From the viewpoint of achieving a rounded shape while having a perovskite-type crystal structure, the amount of dopant in the strontium titanate particles is preferably in the range of 0.1 mol % to 20 mol % relative to strontium, more preferably in the range of 0.1 mol % to 15 mol %, even more preferably in the range of 0.1 mol % to 10 mol %, and even more preferably in the range of 0.2 mol % to 5 mol %.

The strontium titanate particles are preferably strontium titanate particles having a hydrophobically treated surface from the viewpoint of improving the action of the strontium titanate particles, and have a surface hydrophobically treated with a silicon-containing organic compound. More preferably, they are strontium titanate particles.

The average primary particle size of the strontium titanate particles is preferably 10 nm or more and 80 nm or less, more preferably 15 nm or more and 65 nm or less, and even more preferably 25 nm or more and 60 nm or less, from the viewpoint of covering the surfaces of the toner particles with high uniformity.
The average primary particle size of the lanthanum-doped strontium titanate particles is preferably 10 nm or more and 80 nm or less, more preferably 15 nm or more and 65 nm or less, and even more preferably 25 nm or more and 60 nm or less, from the viewpoint of covering the toner particle surfaces with high uniformity.

The strontium titanate particles are preferably monodisperse particles having one peak in a circularity distribution of 0.88 or less in the circularity distribution of the primary particles.
The strontium titanate particles doped with lanthanum are preferably monodisperse particles having one peak in a circularity distribution of 0.88 or less in the circularity distribution of the primary particles.

An example of an embodiment of the toner according to the present embodiment is a mode in which the inorganic particles (B) are only strontium titanate particles (preferably only strontium titanate particles doped with lanthanum).
In the above embodiment, the external addition amount of strontium titanate particles (preferably strontium titanate particles doped with lanthanum) is preferably 0.1 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of toner particles. , more preferably 0.1 parts by mass or more and 2.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1.5 parts by mass or less.

An example of an embodiment of the toner according to the present embodiment is a form in which the inorganic particles (B) include silica particles (B) and titanium compound particles. Here, the silica particles (B) are preferably hydrophobic silica particles (B), and the titanium compound particles are preferably hydrophobic titanium compound particles.
In the above embodiment, the total external addition amount of the silica particles (B) and titanium compound particles is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, and 0.1 parts by mass or more, based on 100 parts by mass of the toner particles. It is more preferably 2.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1.5 parts by mass or less.
In the above embodiment, the content of the titanium compound particles is preferably 0.1 parts by mass or more and 1.0 parts by mass or less, and 0.1 parts by mass or more and 0.8 parts by mass or less, based on 100 parts by mass of the toner particles. More preferably, 0.1 parts by mass or more and 0.5 parts by mass or less are even more preferred.
The above configuration further suppresses inappropriate charge transfer between toners, improves the uniformity of transfer when transferred to a recording medium, and further suppresses color unevenness in an image.

As an example of an embodiment of the toner according to the present embodiment, the inorganic particles (B) include silica particles (B) and strontium titanate particles. Here, the silica particles (B) are preferably hydrophobic silica particles (B), and the strontium titanate particles are preferably hydrophobic strontium titanate particles.
In the above embodiment, the total external addition amount of the silica particles (B) and the strontium titanate particles is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.1 parts by mass or more and 2.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1.5 parts by mass or less, relative to 100 parts by mass of the toner particles.
In the above embodiment, the content of the strontium titanate particles is preferably 0.1 part by mass to 1.0 part by mass, more preferably 0.1 part by mass to 0.8 part by mass, and even more preferably 0.1 part by mass to 0.5 part by mass, based on 100 parts by mass of the toner particles.
It is believed that the above-mentioned form allows the silica particles (B) and strontium titanate particles to be dispersed with high uniformity on the surface of the toner particles, further suppresses inappropriate charge transfer between toner particles, improves the uniformity of transfer when transferred to a recording medium, and further suppresses the occurrence of color unevenness in the image.

As an example of an embodiment of the toner according to the present embodiment, the inorganic particles (B) include silica particles (B) and lanthanum-doped strontium titanate particles, where the silica particles (B) are preferably hydrophobic silica particles (B) and the lanthanum-doped strontium titanate particles are preferably hydrophobic particles.
In the above embodiment, the total external addition amount of the silica particles (B) and the lanthanum-doped strontium titanate particles is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.1 parts by mass or more and 2.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1.5 parts by mass or less, relative to 100 parts by mass of the toner particles.
In the above embodiment, the content of the lanthanum-doped strontium titanate particles is preferably 0.1 parts by mass or more and 1.0 parts by mass or less, more preferably 0.1 parts by mass or more and 0.8 parts by mass or less, and even more preferably 0.1 parts by mass or more and 0.5 parts by mass or less, relative to 100 parts by mass of the toner particles.

The toner according to this embodiment is preferably a toner to which at least hydrophobic silica particles (B) are externally added, more preferably a toner to which hydrophobic silica particles (B) and titanium compound particles are externally added, even more preferably a toner to which hydrophobic silica particles (B) and strontium titanate particles are externally added, and particularly preferably a toner to which hydrophobic silica particles (B) and lanthanum-doped strontium titanate particles are externally added.

[Relationship between silica particles (A) and inorganic particles (B)]
From the viewpoint of suppressing the occurrence of color unevenness in an image, the surface coverage rate Ca of the toner particles by the silica particles (A) and the surface coverage rate Cb of the toner particles by the inorganic particles (B) preferably satisfy the relationship of 0.20≦Ca/(Ca+Cb)≦0.75, more preferably satisfy the relationship of 0.25≦Ca/(Ca+Cb)≦0.70, and further preferably satisfy the relationship of 0.30≦Ca/(Ca+Cb)≦0.65.
When Ca/(Ca+Cb) is 0.20 or more, it is considered that the silica particles (A) and the inorganic particles (B) are dispersed with high uniformity on the surface of the toner particles, and inappropriate charge transfer between the toner particles is further suppressed, the uniformity of transfer is improved when the toner particles are transferred to a recording medium, and the occurrence of color unevenness in the image is further suppressed.
When Ca/(Ca+Cb) is 0.75 or less, it is considered that the silica particles (A) and the inorganic particles (B) are dispersed with high uniformity on the surface of the toner particles, and inappropriate charge transfer between the toner particles is further suppressed, the uniformity of transfer is improved when the toner particles are transferred to a recording medium, and the occurrence of color unevenness in the image is further suppressed.
Here, as the inorganic particles (B) that form the surface coverage Cb, silica particles (B) are preferred, and hydrophobic silica particles (B) are more preferred.

The surface coverage rate Ca of the toner particles by the silica particles (A) is preferably 10% or more and 60% or less, more preferably 10% or more and 50% or less, and even more preferably 10% or more and 30% or less.

The method for measuring the surface coverage Ca and the surface coverage Cb is as follows.
Using a scanning electron microscope (SEM) (S-4800, manufactured by Hitachi High-Technologies) equipped with an energy dispersive X-ray analyzer (EDX device) (EMAX Evolution X-Max 80 mm ² , manufactured by Horiba, Ltd.), an image of the entire toner particle is taken at a magnification of 40,000 times. The external additives present on the surface of each toner particle are classified into silica particles (A) and inorganic particles (B) other than silica particles (A) based on the presence of Mo, N and Si elements by EDX analysis. The image of each toner particle is analyzed using image processing analysis software WinRoof (Mitani Shoji Co., Ltd.) to determine the area of each toner particle, the total area of the silica particles (A) present in each toner particle, and the total area of the inorganic particles (B) present in each toner particle. This image analysis is performed on 100 toner particles, and the total area of the 100 toner particles, the total area of the silica particles (A) present in each toner particle, and the total area of the inorganic particles (B) present in each toner particle are determined. The surface coverage rate Ca and the surface coverage rate Cb are calculated from the following formula.
Ca (%)=(total area of silica particles (A) present in 100 toner particles/total area of 100 toner particles)×100
Cb(%)=(total area of inorganic particles (B) present in 100 toner particles/total area of 100 toner particles)×100

The ratio Da/Db between the average primary particle diameter Da of the silica particles (A) and the average primary particle diameter Db of the inorganic particles (B) is 1 or more and 10 or less from the viewpoint of suppressing color unevenness in the image. It is preferably 1.2 or more and 8 or less, and even more preferably 1.5 or more and 5 or less.
When the ratio Da/Db is 1 or more, the silica particles (A) are less likely to be buried in the inorganic particles (B), and the silica particles (A) cause an appropriate amount of charge to leak from the toner.
When the ratio Da/Db is 10 or less, the silica particles (A) and the inorganic particles (B) are mutually dispersed with high uniformity on the surface of the toner particles, and the silica particles (A) cause an appropriate amount of charge to leak from the toner.

[Other external additives]
The toner according to the present embodiment may contain an external additive other than the silica particles (A) and the inorganic particles (B). Examples of the external additive other than the silica particles (A) and the inorganic particles (B) include resin particles such as polystyrene, polymethyl methacrylate, and melamine resin.

[Toner manufacturing method]
The toner according to the present embodiment is obtained by externally adding an external additive to the toner particles after manufacturing the toner particles.

The toner particles may be manufactured by either a dry manufacturing method (eg, kneading and pulverizing method) or a wet manufacturing method (eg, aggregation coalescence method, suspension polymerization method, dissolution/suspension method, etc.). There are no particular restrictions on these manufacturing methods, and known manufacturing methods may be employed. Among these, it is preferable to obtain toner particles by an aggregation coalescence method.

Specifically, for example, when toner particles are produced by the aggregation and coalescence method,
The toner particles are manufactured through a process including a step of preparing a resin particle dispersion in which resin particles to be a binder resin are dispersed (resin particle dispersion preparation process), a step of aggregating the resin particles (or other particles, if necessary) in the resin particle dispersion (in a dispersion after mixing with other particle dispersions, if necessary) to form aggregated particles (aggregated particle formation process), and a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed, to fuse and coalesce the aggregated particles to form toner particles (fusion and coalescence process).

The details of each step will be explained below.
In the following description, a method for obtaining toner particles containing a colorant and a release agent will be described, and the colorant and release agent are used as necessary. Of course, other additives than the colorant and mold release agent may be used.

-Resin particle dispersion preparation process-
For example, a colorant particle dispersion in which colorant particles are dispersed and a release agent particle dispersion in which release agent particles are dispersed are prepared together with a resin particle dispersion in which resin particles serving as a binder resin are dispersed.

The resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

Examples of the dispersion medium used in the resin particle dispersion include an aqueous medium.
Examples of the aqueous medium include water such as distilled water and ion-exchanged water, alcohols, and the like. These may be used alone or in combination of two or more.

Examples of the surfactant include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; polyethylene glycol Examples include nonionic surfactants such as surfactants based on surfactants, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly mentioned. Nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants.
One type of surfactant may be used alone, or two or more types may be used in combination.

In the resin particle dispersion, the resin particles are dispersed in the dispersion medium by general dispersion methods such as a rotary shear homogenizer, a ball mill with media, a sand mill, or a dyno mill. Depending on the type of resin particles, the resin particles may be dispersed in the dispersion medium by a phase inversion emulsification method. The phase inversion emulsification method is a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase) to neutralize it, and then an aqueous medium (W phase) is added to invert the phase from W/O to O/W, dispersing the resin in particulate form in the aqueous medium.

The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably from 0.01 μm to 1 μm, more preferably from 0.08 μm to 0.8 μm, and even more preferably from 0.1 μm to 0.6 μm.
The volume average particle size of the resin particles is measured by using a particle size distribution obtained by measurement using a laser diffraction particle size distribution measuring device (for example, LA-700 manufactured by Horiba, Ltd.), subtracting a cumulative distribution from the small particle size side for the volume of the divided particle size range (channel), and measuring the particle size at which the cumulative distribution is 50% of all particles as the volume average particle size D50v. The volume average particle sizes of the particles in other dispersions are also measured in the same manner.

The content of resin particles in the resin particle dispersion is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

In the same manner as the resin particle dispersion, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared. In other words, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion are the same for the colorant particles dispersed in the colorant particle dispersion, and the release agent particles dispersed in the release agent particle dispersion.

-Agglomerated particle formation process-
Next, the resin particle dispersion liquid, the colorant particle dispersion liquid, and the release agent particle dispersion liquid are mixed together.
Then, in the mixed dispersion, the resin particles, the colorant particles, and the release agent particles are hetero-aggregated to form aggregated particles containing the resin particles, the colorant particles, and the release agent particles and having a diameter close to that of the target toner particles.

Specifically, for example, a flocculant is added to the mixed dispersion, the pH of the mixed dispersion is adjusted to acidic (for example, pH 2 or more and 5 or less), and a dispersion stabilizer is added as necessary, and then the resin particles are (Specifically, for example, the glass transition temperature of the resin particles -30°C or higher and the glass transition temperature -10°C or lower) to agglomerate the particles dispersed in the mixed dispersion, form agglomerated particles. In the agglomerated particle forming step, for example, a flocculant is added to the mixed dispersion at room temperature (e.g., 25°C) while stirring with a rotary shear type homogenizer, and the pH of the mixed dispersion is adjusted to acidic (e.g., pH 2 or more and 5 or less). However, heating may be performed after adding a dispersion stabilizer if necessary.

Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant contained in the mixed dispersion, an inorganic metal salt, and a divalent or higher-valent metal complex. When a metal complex is used as the flocculant, the amount of surfactant used is reduced and charging characteristics are improved.
Along with the flocculant, an additive that forms a complex or similar bond with the metal ion of the flocculant may be used as necessary. A chelating agent is preferably used as this additive.

Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; inorganic metal salts such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Polymer; etc. are mentioned.
As the chelating agent, a water-soluble chelating agent may be used. Examples of the chelating agent include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; aminocarboxylic acids such as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA); It will be done.
The amount of the chelating agent added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less, more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, based on 100 parts by mass of the resin particles.

- Fusion and integration process -
Next, the aggregated particle dispersion liquid in which the aggregated particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the resin particles (for example, a temperature 10° C. to 30° C. higher than the glass transition temperature of the resin particles) to fuse and coalesce the aggregated particles to form toner particles.

Through the above steps, toner particles are obtained.
After obtaining an aggregated particle dispersion liquid in which aggregated particles are dispersed, the aggregated particle dispersion liquid and a resin particle dispersion liquid in which resin particles are dispersed are further mixed, and further resin particles are attached to the surface of the aggregated particles. The second agglomerated particle dispersion liquid in which the second agglomerated particles are dispersed is heated to fuse and unite the second agglomerated particles to form a core. - Toner particles may be manufactured through a step of forming toner particles having a shell structure.

After the fusion/coalescence process is completed, the toner particles in the dispersion are subjected to a known washing process, solid-liquid separation process, and drying process to obtain dry toner particles. In the washing step, from the viewpoint of chargeability, it is preferable to perform sufficient displacement washing with ion-exchanged water. In the solid-liquid separation step, suction filtration, pressure filtration, etc. are preferably performed from the viewpoint of productivity. From the viewpoint of productivity, the drying process is preferably carried out by freeze drying, flash drying, fluidized drying, vibrating fluidized drying, or the like.

The toner according to this embodiment is produced, for example, by adding an external additive to the obtained dry toner particles and mixing them. The mixing can be carried out, for example, using a V blender, a Henschel mixer, a Loedige mixer, or the like. If necessary, coarse particles of the toner can be removed using a vibrating sieve, an air sieve, or the like.

<Electrostatic Image Developer>
The electrostatic image developer according to this embodiment contains at least the toner according to this embodiment.
The electrostatic image developer according to the present embodiment may be a one-component developer containing only the toner according to the present embodiment, or may be a two-component developer in which the toner is mixed with a carrier.

There are no particular limitations on the carrier, and known carriers may be used. Examples of carriers include coated carriers in which the surface of a core material made of magnetic powder is coated with resin; magnetic powder-dispersed carriers in which magnetic powder is dispersed in a matrix resin; porous magnetic powder impregnated with resin. and resin-impregnated carriers.
The magnetic powder-dispersed carrier and the resin-impregnated carrier may be carriers in which the constituent particles of the carrier are used as a core material and the surface thereof is coated with a resin.

Examples of magnetic powders include magnetic metals such as iron, nickel, and cobalt; magnetic oxides such as ferrite and magnetite; and the like.

Examples of the resin and matrix resin for coating include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene acrylic acid ester copolymer, straight silicone resin or its modified product containing organosiloxane bonds, fluororesin, polyester, polycarbonate, phenolic resin, epoxy resin, etc. The resin and matrix resin for coating may contain other additives such as conductive particles. Examples of the conductive particles include particles of metals such as gold, silver, copper, etc., carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, potassium titanate, etc.

Examples of methods for coating the surface of the core material with a resin include a method of coating with a coating layer-forming solution prepared by dissolving the coating resin and various additives (used as necessary) in a suitable solvent. The solvent is not particularly limited and may be selected taking into consideration the type of resin used, coating suitability, etc.
Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer; a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material; a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air; and a kneader coater method in which the core material of the carrier and the solution for forming a coating layer are mixed in a kneader coater and then the solvent is removed.

The mixing ratio (mass ratio) of toner and carrier in the two-component developer is preferably toner:carrier = 1:100 to 30:100, more preferably 3:100 to 20:100.

<Image forming apparatus, image forming method>
An image forming apparatus and an image forming method according to this embodiment will be described.
The image forming apparatus according to the present embodiment includes an image carrier, a charging means for charging the surface of the image carrier, an electrostatic image forming means for forming an electrostatic charge image on the surface of the charged image carrier, and an electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier. a developing means that contains an image developer and develops the electrostatic image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer; and a fixing means for fixing the toner image transferred to the surface of the recording medium. The electrostatic image developer according to this embodiment is applied as the electrostatic image developer.

The image forming apparatus according to the present embodiment includes a charging process of charging the surface of the image carrier, an electrostatic image forming process of forming an electrostatic charge image on the surface of the charged image carrier, and an electrostatic charge according to the present embodiment. a developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with an image developer; a transfer step of transferring the toner image formed on the surface of the image carrier onto the surface of a recording medium; An image forming method (image forming method according to this embodiment) including a fixing step of fixing a toner image transferred to the surface of a recording medium is carried out.

The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as a direct transfer type apparatus in which a toner image formed on the surface of an image holder is directly transferred to a recording medium; an intermediate transfer type apparatus in which a toner image formed on the surface of an image holder is primarily transferred to the surface of an intermediate transfer body, and the toner image transferred to the surface of the intermediate transfer body is secondarily transferred to the surface of a recording medium; an apparatus equipped with a cleaning means for cleaning the surface of the image holder after the transfer of the toner image and before charging; and an apparatus equipped with a discharging means for irradiating the surface of the image holder with discharging light to discharge it after the transfer of the toner image and before charging it.
When the image forming apparatus according to the present embodiment is an intermediate transfer type apparatus, the transfer means has, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means which primarily transfers the toner image formed on the surface of the image carrier onto the surface of the intermediate transfer body, and a secondary transfer means which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of a recording medium.

In the image forming apparatus according to the present embodiment, for example, the portion including the developing means may be a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge containing the electrostatic image developer according to the present embodiment and provided with a developing means is suitably used.

An example of an image forming apparatus according to this embodiment will be shown below, but the present invention is not limited thereto. In the following explanation, the main parts shown in the figures will be explained, and the explanation of the others will be omitted.

In the following description, a four-tandem image forming device with four image forming units lined up will be described as an example of an image forming device according to this embodiment. The tandem image forming device is not limited to this, and may be a five-tandem image forming device with five image forming units lined up, or a six-tandem image forming device with six image forming units lined up, etc.

FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to the present embodiment.
The image forming apparatus shown in Fig. 1 includes first to fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) of an electrophotographic type that output images of the respective colors of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter, sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged in parallel at predetermined distances from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may be process cartridges that are detachably attached to the image forming apparatus.

An intermediate transfer belt (one example of an intermediate transfer body) 20 is provided above each of the units 10Y, 10M, 10C, and 10K and extends through each unit. The intermediate transfer belt 20 is provided wrapped around a drive roll 22 and a support roll 24, and runs in a direction from the first unit 10Y to the fourth unit 10K. A force is applied to the support roll 24 by a spring (not shown) or the like in a direction away from the drive roll 22, and tension is applied to the intermediate transfer belt 20 wrapped around them. An intermediate transfer body cleaning device 30 is provided on the image carrier side of the intermediate transfer belt 20, facing the drive roll 22.
The developing devices (examples of developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K are supplied with yellow, magenta, cyan, and black toners contained in toner cartridges 8Y, 8M, 8C, and 8K, respectively.

The first to fourth units 10Y, 10M, 10C, and 10K have the same configuration and operation, so here we will explain the first unit 10Y, which forms a yellow image and is arranged upstream in the direction in which the intermediate transfer belt travels, as a representative.

The first unit 10Y has a photoconductor 1Y that acts as an image carrier. Around the photoconductor 1Y, a charging roll (an example of a charging means) 2Y that charges the surface of the photoconductor 1Y to a predetermined potential, an exposure device (an example of an electrostatic image forming means) 3 that exposes the charged surface to a laser beam 3Y based on a color-separated image signal to form an electrostatic image, a developing device (an example of a developing means) 4Y that supplies charged toner to the electrostatic image to develop it, a primary transfer roll 5Y (an example of a primary transfer means) that transfers the developed toner image onto an intermediate transfer belt 20, and a photoconductor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer are arranged in this order.
The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoconductor 1Y. A bias power supply (not shown) that applies a primary transfer bias is connected to the primary transfer rolls 5Y, 5M, 5C, and 5K of each unit. Each bias power supply changes the value of the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

The operation of forming a yellow image in the first unit 10Y will be described below.
First, prior to operation, the surface of the photoreceptor 1Y is charged to a potential of -600V to -800V by the charging roll 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (for example, a volume resistivity of 1×10 ⁻⁶ Ωcm or less at 20° C.). This photosensitive layer normally has a high resistance (the resistance of a general resin), but when it is irradiated with a laser beam, it has a property that the specific resistance of the portion irradiated with the laser beam changes. Therefore, the surface of the charged photoreceptor 1Y is irradiated with a laser beam 3Y from the exposure device 3 according to image data for yellow sent from a control section (not shown). As a result, an electrostatic charge image of a yellow image pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic image is an image formed on the surface of the photoconductor 1Y by electrostatic charging, and is
As a result, the resistivity of the irradiated portion of the photosensitive layer decreases, causing the electric charges on the surface of the photoconductor 1Y to flow, while the electric charges remain in the portion not irradiated by the laser beam 3Y, forming a so-called negative latent image.
The electrostatic image formed on the photoconductor 1Y rotates to a predetermined developing position as the photoconductor 1Y travels. At this developing position, the electrostatic image on the photoconductor 1Y is developed into a toner image by the developing device 4Y and made visible.

The developing device 4Y contains an electrostatic image developer that contains, for example, at least yellow toner and a carrier. The yellow toner is triboelectrically charged by being stirred inside the developing device 4Y, and is held on a developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoconductor 1Y. As the surface of the photoconductor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoconductor 1Y, and the latent image is developed with the yellow toner. The photoconductor 1Y on which the yellow toner image has been formed continues to run at a predetermined speed, and the toner image developed on the photoconductor 1Y is transported to a predetermined primary transfer position.

When the yellow toner image on the photoconductor 1Y is conveyed to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5Y, and electrostatic force from the photoconductor 1Y toward the primary transfer roll 5Y acts on the toner image, causing the photoconductor 1Y to transfer to the primary transfer position. The toner image on body 1Y is transferred onto intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the toner polarity (-), and is controlled to, for example, +10 μA by a control section (not shown) in the first unit 10Y.
The toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

The primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M is also controlled in accordance with the first unit.
In this way, the intermediate transfer belt 20, onto which the yellow toner image has been transferred in the first unit 10Y, is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed, resulting in multiple transfer. be done.

The intermediate transfer belt 20 to which the toner images of four colors have been multiple-transferred through the first to fourth units includes the intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and an image holding surface of the intermediate transfer belt 20. This leads to a secondary transfer section comprised of a secondary transfer roll (an example of secondary transfer means) 26 disposed on the side. On the other hand, recording paper (an example of a recording medium) P is fed via a supply mechanism to the gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact with each other at a predetermined timing, and the secondary transfer bias is applied to the support roll. 24. The transfer bias applied at this time has the same polarity (-) as the polarity (-) of the toner, and electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, and The toner image is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer portion, and is voltage controlled.

Thereafter, the recording paper P is fed into the pressure contact section (nip section) of a pair of fixing rolls in the fixing device (an example of fixing means) 28, and the toner image is fixed onto the recording paper P, forming a fixed image. .

The recording paper P onto which the toner image is transferred can be, for example, plain paper used in electrophotographic copying machines, printers, etc. In addition to the recording paper P, other examples of the recording medium include overhead projector sheets and the like.
In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper in which the surface of ordinary paper is coated with a resin or the like, art paper for printing, etc. are preferably used.

After the color image has been fixed, the recording paper P is conveyed toward the discharge section, and the series of color image forming operations is completed.

<Process cartridges, toner cartridges>
The process cartridge according to this embodiment will be described.
The process cartridge according to this embodiment is a process cartridge that contains the electrostatic image developer according to this embodiment, is equipped with a developing means that develops an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image, and is detachably attached to an image forming apparatus.

The process cartridge according to the present embodiment is not limited to the above configuration, and includes a developing means, and other means selected from among, for example, an image carrier, a charging means, an electrostatic image forming means, and a transfer means, as necessary. The configuration may include at least one of:

Below, an example of a process cartridge according to this embodiment is shown, but the invention is not limited to this. In the following explanation, the main parts shown in the figure will be explained, and the explanation of the rest will be omitted.

FIG. 2 is a schematic diagram showing the process cartridge according to the present embodiment.
The process cartridge 200 shown in FIG. 2 is configured by, for example, a housing 117 having a mounting rail 116 and an opening 118 for exposure, and integrally combining and holding a photoconductor 107 (an example of an image carrier), a charging roll 108 (an example of a charging means) provided around the photoconductor 107, a developing device 111 (an example of a developing means), and a photoconductor cleaning device 113 (an example of a cleaning means), which are formed into a cartridge.
In FIG. 2, reference numeral 109 denotes an exposure device (an example of an electrostatic image forming means), 112 denotes a transfer device (an example of a transfer means), 115 denotes a fixing device (an example of a fixing means), and 300 denotes a recording paper (an example of a recording medium).

Next, a toner cartridge according to this embodiment will be described.
The toner cartridge according to this embodiment is a toner cartridge that accommodates the toner according to this embodiment and is detachable from an image forming apparatus. The toner cartridge accommodates replenishment toner to be supplied to a developing means provided within the image forming apparatus.

The image forming device shown in FIG. 1 is an image forming device configured to allow toner cartridges 8Y, 8M, 8C, and 8K to be attached and detached, and developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to each developing device (color) by toner supply pipes (not shown). When the toner contained in a toner cartridge becomes low, the toner cartridge is replaced.

Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples.
In the following description, unless otherwise specified, "parts" and "%" are based on mass.
Syntheses, processing, preparations, etc. were carried out at room temperature (25° C.±3° C.) unless otherwise noted.

<Manufacture of carrier>
・Cyclohexyl methacrylate resin (weight average molecular weight 50,000): 56 parts ・Carbon black (manufactured by Cabot, VXC72): 6 parts ・Toluene: 250 parts ・Isopropyl alcohol: 50 parts The above materials and glass beads (diameter 1 mm, toluene and (same amount) was placed in a sand mill and stirred at a rotation speed of 190 rpm for 30 minutes to obtain a coating agent.

1,000 parts of ferrite particles (volume average particle size 35 μm) and 150 parts of coating agent were placed in a kneader and mixed at room temperature (25°C) for 20 minutes. The mixture was then heated to 70°C and dried under reduced pressure. The dried product was cooled to room temperature (25°C), removed from the kneader, and sieved through a 75 μm mesh to remove coarse powder, yielding a carrier.

<Production of Toner Particles>
[Preparation of Resin Particle Dispersion (1)]
Ethylene glycol: 37 parts Neopentyl glycol: 65 parts 1,9-nonanediol: 32 parts Terephthalic acid: 96 parts The above materials were charged into a flask, and the temperature was raised to 200°C over 1 hour. After confirming that the reaction system was stirred uniformly, 1.2 parts of dibutyltin oxide were added. The temperature was raised to 240°C over 6 hours while distilling off the water produced, and stirring was continued at 240°C for 4 hours to obtain a polyester resin (acid value 9.4 mgKOH/g, weight average molecular weight 13,000, glass transition temperature 62°C). This polyester resin was transferred in a molten state to an emulsifying and dispersing machine (Cavitron CD1010, Eurotech) at a rate of 100 g per minute. Separately, a 0.37% concentration dilute ammonia water obtained by diluting reagent ammonia water with ion-exchanged water was placed in a tank, and the mixture was transferred to the emulsifying and dispersing machine at a rate of 0.1 liters per minute simultaneously with the polyester resin while being heated to 120°C with a heat exchanger. The emulsifying disperser was operated under conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg/cm 2 to obtain a resin particle dispersion (1) having a volume average particle size of 160 nm and a solid content of 30%.

[Preparation of resin particle dispersion (2)]
- Decanedioic acid: 81 parts - Hexanediol: 47 parts Charge the above materials into a flask, raise the temperature to 160°C over 1 hour, and after confirming that the reaction system is uniformly stirred, add dibutyltin oxide. 0.03 part of was added. The temperature was raised to 200°C over 6 hours while distilling off the produced water, and stirring was continued at 200°C for 4 hours. Next, the reaction solution was cooled, solid-liquid separation was performed, and the solid material was dried at a temperature of 40° C./under reduced pressure to obtain a polyester resin (C1) (melting point: 64° C., weight average molecular weight: 15,000).

Polyester resin (C1): 50 parts Anionic surfactant (Neogen SC, Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts Ion-exchanged water: 200 parts The above materials were heated to 120° C. and thoroughly dispersed with a homogenizer (Ultra Turrax T50, IKA Corporation), and then dispersed with a pressure discharge homogenizer. When the volume average particle size reached 180 nm, the particles were collected to obtain a resin particle dispersion (2) with a solid content of 20%.

[Preparation of Colorant Particle Dispersion (1)]
Cyan pigment (Pigment Blue 15:3, manufactured by Dainichi Seiyaku Color & Chemicals Mfg. Co., Ltd.): 50 parts Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts Ion-exchanged water: 200 parts The above materials were mixed and dispersed for 1 hour using a high-pressure impact disperser (Ultimizer HJP30006, manufactured by Sugino Machine Co., Ltd.) to obtain colorant particle dispersion (1) having a volume average particle size of 180 nm and a solids content of 20%.

[Preparation of Release Agent Particle Dispersion (1)]
Paraffin wax (HNP-9, manufactured by Nippon Seiro Co., Ltd.): 50 parts Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts Ion-exchanged water: 200 parts The above materials were heated to 120° C. and thoroughly dispersed with a homogenizer (Ultra Turrax T50, manufactured by IKA Corporation), and then dispersed with a pressure discharge homogenizer. When the volume average particle size reached 200 nm, the particles were collected to obtain a release agent particle dispersion (1) with a solid content of 20%.

[Preparation of toner particles (1)]
・Resin particle dispersion (1): 150 parts ・Resin particle dispersion (2): 50 parts ・Colorant particle dispersion (1): 25 parts ・Release agent particle dispersion (1): 35 parts ・Polychlorination Aluminum: 0.4 parts / Ion exchange water: 100 parts The above materials were put into a round stainless steel flask, thoroughly mixed and dispersed using a homogenizer (Ultra Turrax T50, IKA), and then the inside of the flask was stirred. While heating, the mixture was heated to 48°C in a heating oil bath. After maintaining the inside of the reaction system at 48° C. for 60 minutes, 70 parts of resin particle dispersion (1) was slowly added. Next, the pH was adjusted to 8.0 using a 0.5 mol/L aqueous sodium hydroxide solution, the flask was sealed, the stirring shaft was magnetically sealed, and the mixture was heated to 90°C for 30 minutes while stirring. held. Next, the mixture was cooled at a temperature decreasing rate of 5° C./min, separated into solid and liquid, and thoroughly washed with ion-exchanged water. Next, the solid-liquid was separated, redispersed in ion-exchanged water at 30°C, and washed by stirring at a rotation speed of 300 rpm for 15 minutes. This washing operation was repeated six more times, and solid-liquid separation was performed when the pH of the filtrate became 7.54 and the electrical conductivity became 6.5 μS/cm. The solid content was vacuum dried for 24 hours to obtain toner particles (1). The volume average particle diameter of toner particles (1) was 5.7 μm.

<Production of Silica Particles (A)>
[Preparation of alkaline catalyst solution]
Methanol and aqueous ammonia (NH ₄ OH) in the amounts and concentrations shown in Table 1 were placed in a glass reaction vessel equipped with a metallic stirring rod, a dropping nozzle, and a thermometer, and mixed with stirring to obtain an alkaline catalyst solution.

[Granulation of silica base particles by the sol-gel method]
The temperature of the alkaline catalyst solution was adjusted to 40° C., and the alkaline catalyst solution was purged with nitrogen. While the temperature of the alkaline catalyst solution was kept at 40° C. and the solution was stirred, tetramethoxysilane (TMOS) in the amount shown in Table 1 and 124 parts of ammonia water (NH ₄ OH) with a catalyst (NH ₃ ) concentration of 7.9% were simultaneously dropped to obtain a silica base particle suspension.

[Addition of silane coupling agent]
Methyltrimethoxysilane (MTMS) was added in the amount shown in Table 1 while the temperature of the silica mother particle suspension was maintained at 40° C. and stirred. After the addition was completed, stirring was continued for 120 minutes to cause MTMS to react, and at least a portion of the surface of the silica mother particles was coated with the MTMS reaction product.

[Addition of molybdenum nitrogen-containing compound]
An alcohol solution was prepared by diluting the molybdenum nitrogen-containing compound in the amount shown in Table 1 with butanol. This alcohol solution was added to the silica mother particle suspension after the reaction with the silane coupling agent, and the mixture was stirred for 100 minutes while maintaining the liquid temperature at 30°C. The amount of alcohol solution added was such that the number of parts of the molybdenum nitrogen-containing compound was as shown in Table 1 with respect to 100 parts by mass of the solid content of the silica mother particle suspension.
"TP-415" in Table 1 is a quaternary ammonium salt of molybdate (Hodogaya Chemical Industry Co., Ltd.).

[Drying]
The suspension after the addition of the molybdenum nitrogen-containing compound was transferred to a reaction tank for drying. While stirring the suspension, liquefied carbon dioxide was injected into the reaction tank, and the temperature and pressure in the reaction tank were raised to 150°C and 15 MPa, and the suspension was continued to be stirred while maintaining the temperature and pressure to maintain the supercritical state of carbon dioxide. Carbon dioxide was introduced and discharged at a flow rate of 5 L/min, and the solvent was removed over 120 minutes to obtain silica particles (A). Silica particles (A1) to (A13) were produced separately by adjusting the amounts of ammonia water, silane coupling agent, and molybdenum nitrogen-containing compound added.

[Fluorescent X-ray analysis]
The silica particles (A) were subjected to fluorescent X-ray analysis according to the measurement method described above to determine the net intensity N _Mo of the molybdenum element and the net intensity N _Si of the silicon element, and the net intensity ratio N _Mo /N _Si was calculated.

The average primary particle size, circularity, and net intensity ratio of silica particles (A1) to (A13) are shown in Table 1.

<Production of Hydrophobic Silica Particles (B)>
Hydrophobic silica particles (B1) to (B8) were produced as follows: Hydrophobic silica particles (B1) to (B8) are silica particles that do not contain a molybdenum nitrogen-containing compound.
Silica particles were granulated by a known sol-gel method, and the average primary particle size and average circularity of the silica particles were adjusted by controlling the reaction time and reaction temperature of the sol-gel method.
The silica particles produced by the sol-gel method were surface-treated with a hydrophobic treatment agent to obtain hydrophobic silica particles. The volume resistivity of the hydrophobic silica particles was adjusted by the amount of the hydrophobic treatment agent used to treat the silica particles.
The average primary particle size, circularity and volume resistivity of the hydrophobic silica particles (B1) to (B8) are shown in Table 2.

<Production of strontium titanate particles>
[Manufacture of strontium titanate particles (1)]
Desulfurized and peptized titanium source metatitanic acid was collected in an amount of 0.7 mol as TiO ₂ and placed in a reaction vessel. Next, 0.77 mol of strontium chloride aqueous solution was added to the reaction vessel so that the SrO/TiO ₂ molar ratio was 1.1. Next, a solution of lanthanum oxide dissolved in nitric acid was added to the reaction vessel in an amount such that lanthanum (La) was 0.5 mole per 100 moles of strontium. The initial TiO ₂ concentration in the mixed solution of the three materials was set to 0.75 mol/L. Next, the mixed solution was stirred, the mixed solution was heated to 92°C, and while the liquid temperature was maintained at 92°C and stirred, 153 mL of a 10N aqueous sodium hydroxide solution was added over 1.5 hours, and the liquid temperature was further increased. Stirring was continued for 1 hour while maintaining the temperature at 92°C. Next, the reaction solution was cooled to 40° C., hydrochloric acid was added until the pH reached 5.4, and the mixture was stirred for 1 hour. The precipitate was then washed by repeated decantation and redispersion in water. Hydrochloric acid was added to the slurry containing the washed precipitate to adjust the pH to 6.5, solid-liquid separation was performed by filtration, and the solid content was dried. An ethanol solution of i-butyltrimethoxysilane (i-BTMS) was added to the dried solid content in an amount such that i-BTMS was 20 parts per 100 parts of the solid content, and the mixture was stirred for 1 hour. Solid-liquid separation was performed by filtration, and the solid content was dried in the air at 130°C for 7 hours to obtain strontium titanate particles (1).

[Production of strontium titanate particles (2) to (8)]
Strontium titanate particles (2) to (8) were obtained in the same manner as in the production of strontium titanate particles (1), except that the amount of lanthanum doped and the time taken for the 10N aqueous sodium hydroxide solution to be dropped were changed.

Table 3 shows the average primary particle diameter and circularity of the strontium titanate particles (1) to (8).

<Manufacture of toner and two-component developer>
[Examples 1 to 22 and Comparative Examples 1 to 3]
100 parts of toner particles (1), any of silica particles (A1) to (A13), and any of hydrophobic silica particles (B1) to (B8) were mixed in the amounts shown in Table 4 using a Henschel mixer. The mixture was sieved using a vibrating sieve with an opening of 45 μm to obtain a toner. 8 parts of toner and 100 parts of carrier were placed in a V-blender, stirred, and sieved through a sieve with an opening of 212 μm to obtain a two-component developer.

[Examples 23 to 44 and Comparative Examples 4 to 6]
100 parts of toner particles (1), any of silica particles (A1) to (A13), and any of strontium titanate particles (1) to (8) were mixed in a Henschel mixer in the amounts shown in Table 5. The mixture was sieved using a vibrating sieve with an opening of 45 μm to obtain a toner. 8 parts of toner and 100 parts of carrier were placed in a V-blender, stirred, and sieved through a sieve with an opening of 212 μm to obtain a two-component developer.

[Examples 45 to 63 and Comparative Examples 7 to 8]
A toner was obtained by mixing 100 parts of toner particles (1), any one of silica particles (A1) to (A13), hydrophobic silica particles (B1), and any one of strontium titanate particles (1) to (8) in the amounts shown in Table 6 in a Henschel mixer and sieving the mixture through a vibrating sieve with an opening of 45 μm. A two-component developer was obtained by mixing 8 parts of toner and 100 parts of carrier in a V blender, stirring the mixture, and sieving the mixture through a sieve with an opening of 212 μm.

<Performance evaluation>
[Color unevenness]
An electrophotographic, intermediate transfer, six-series tandem image forming apparatus was prepared. All six developing units were filled with a two-component cyan developer. The developer was left overnight in an environment of 28° C. and 85% relative humidity to adjust the temperature and humidity.
In an environment of 28°C temperature and 85% relative humidity, each of the two upstream engines continuously output 10,000 test images of 100%, 20%, and 1% density on A4 plain paper. Next, the four upstream engines output 10 test images of solid images with an image density of 30%, and the two downstream engines output 10 test images of solid images with an image density of 80% on A4 plain paper. The image quality of the 10 sheets was visually observed, and color unevenness was classified as follows. The results are shown in Tables 4 to 6.
A: 0 sheets with color unevenness B: 1 sheet with color unevenness C: 2 to 3 sheets with color unevenness D: 4 to 7 sheets with color unevenness E: 8 to 9 sheets with color unevenness F: 10 sheets with color unevenness

In Tables 4 to 6, the "amount added" is the number of parts per 100 parts by mass of the toner particles.
In Table 6, the average primary particle size Db of the inorganic particles (B) is the weighted average of the average primary particle size Db1 of the hydrophobic silica particles (B) and the average primary particle size Db2 of the strontium titanate particles (the average of the average primary particle sizes of both particles weighted by the amounts added).

(((1)))
toner particles;
Silica particles (A) containing a nitrogen element-containing compound containing a molybdenum element, externally added to the toner particles;
Inorganic particles (B) other than the silica particles (A) externally added to the toner particles,
The silica particles (A) have a ratio N _Mo /N _Si of the net strength N _Mo of the molybdenum element and the net strength N _Si of the silicon element measured by X-ray fluorescence analysis from 0.035 to 0.45. ,
The average primary particle size of the inorganic particles (B) is 10 nm or more and 80 nm or less,
Toner for developing electrostatic images.
(((2)))
The toner for developing an electrostatic image according to ((1)), wherein the ratio N _Mo /N _Si of the silica particles (A) is 0.05 or more and 0.30 or less.
(((3)))
When the overall circularity of the silica particles (A) and the inorganic particles (B) externally added to the toner particles is measured, the circularity distribution has at least two peaks, and the circularity exceeds 0.88. The toner for developing an electrostatic image according to (((1))) or (((2))), wherein the toner has at least one peak in the region and has at least one peak in the region having a circularity of 0.88 or less.
(((4)))
The electrostatic image development according to any one of (((1))) to (((3))), wherein the inorganic particles (B) include silica particles (B) other than the silica particles (A). toner.
(((5)))
The toner for developing an electrostatic image according to any one of (((1))) to (((4))), wherein the inorganic particles (B) include titanium compound particles.
(((6)))
The toner for developing an electrostatic image according to any one of (((1))) to (((4))), wherein the inorganic particles (B) include strontium titanate particles.
(((7)))
As described in any one of (((1))) to (((5))), wherein the inorganic particles (B) include silica particles (B) other than the silica particles (A) and titanium compound particles. Toner for developing electrostatic images.
(((8)))
The toner for developing an electrostatic image according to ((7))), wherein the content of the titanium compound particles is 0.1 part by mass or more and 1.0 parts by mass or less based on 100 parts by mass of the toner particles.
(((9)))
Any one of (((1))) to (((6))), wherein the inorganic particles (B) contain silica particles (B) other than the silica particles (A) and strontium titanate particles. The toner for developing electrostatic images described above.
(((10)))
The toner for developing an electrostatic image according to ((9))), wherein the content of the strontium titanate particles is 0.1 part by mass or more and 1.0 parts by mass or less based on 100 parts by mass of the toner particles. .
(((11)))
The volume resistivity of the inorganic particles (B) is 1.0×10 ¹⁴ Ω·cm or more and 1.0×10 ¹⁷ Ω·cm or more, (((1))) to (((10))). The toner for developing an electrostatic image according to any one of the above.
(((12)))
The relationship between the surface coverage Ca of the toner particles by the silica particles (A) and the surface coverage Cb of the toner particles by the inorganic particles (B) is 0.20≦Ca/(Ca+Cb)≦0.75. The toner for developing an electrostatic image according to any one of ((1)) to ((11)), which satisfies the following.
(((13)))
The toner for developing an electrostatic image according to (((12))), wherein the surface coverage Ca of the toner particles by the silica particles (A) is 10% or more and 60% or less.
(((14)))
(((1))) to ((( 13)) The toner for developing an electrostatic image according to any one of)).
(((15)))
The nitrogen element-containing compound containing the molybdenum element is at least one selected from the group consisting of a quaternary ammonium salt containing the molybdenum element, and a mixture of a quaternary ammonium salt and a metal oxide containing the molybdenum element. The toner for developing an electrostatic image according to any one of (((1))) to (((14))).
(((16)))
The silica particles (A) are silica particles having a coating structure made of a reaction product of a silane coupling agent and a nitrogen element-containing compound containing the molybdenum element attached to the coating structure, (((1) )) to (((15))).
(((17)))
The toner for developing an electrostatic image according to ((16)), wherein the silane coupling agent contains an alkyltrialkoxysilane.

(((18)))
An electrostatic image developer comprising the toner for developing electrostatic images according to any one of ((1))) to (((17))).
(((19)))
The toner for developing an electrostatic image according to any one of ((1))) to ((17)) is contained in the container,
A toner cartridge that is detachably attached to an image forming apparatus.
(((20)))
a developing means for developing an electrostatic image formed on a surface of an image carrier into a toner image by using the electrostatic image developer according to (((18))),
A process cartridge that is detachably attached to an image forming apparatus.
(((21)))
An image carrier;
a charging means for charging the surface of the image carrier;
an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier;
a developing means for containing the electrostatic image developer according to (((18))) and developing the electrostatic image formed on the surface of the image carrier into a toner image by the electrostatic image developer;
a transfer means for transferring the toner image formed on the surface of the image carrier to a surface of a recording medium;
a fixing means for fixing the toner image transferred onto the surface of the recording medium;
An image forming apparatus comprising:
(((22)))
a charging step of charging the surface of the image carrier;
an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier;
a developing step of developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer according to (((18)));
a transfer step of transferring the toner image formed on the surface of the image carrier onto a surface of a recording medium;
a fixing step of fixing the toner image transferred onto the surface of the recording medium;
The image forming method according to claim 1,

According to the invention pertaining to ((1)), ((3)), ((4)), ((5)), ((6)), ((7)), ((9)), ((11)), ((15)), ((16)) or ((17)), there is provided a toner for developing electrostatic images which is less prone to color unevenness in silica particles having a nitrogen-containing compound containing molybdenum externally added to the toner particles, as compared to a case in which the ratio _NMo / _NSi of the net intensity NMo of molybdenum to the net intensity _NSi of silicon measured by fluorescent X-ray analysis is less than 0.035 _or exceeds 0.45.
According to the invention related to (((2))), there is provided a toner for developing electrostatic images, in which in silica particles having a nitrogen-containing compound containing molybdenum externally added to the toner particles, the ratio NMo/ _NSi of the net intensity _NMo of elemental molybdenum to the net intensity NSi of elemental silicon, as measured by fluorescent X-ray analysis, is less than 0.05 or exceeds 0.30, and which is less likely to cause color unevenness, as compared with a case in which the ratio _NMo / _NSi of the net intensity NMo of elemental molybdenum to the net intensity NSi of elemental silicon, as measured by fluorescent X-ray analysis, is less than 0.05 or exceeds 0.30.
According to the invention related to ((8))), there is provided a toner for developing electrostatic images which is less prone to color unevenness compared to a case in which the inorganic particles (B) contain silica particles (B) other than the silica particles (A) and titanium compound particles, and the content of the titanium compound particles is less than 0.1 part by mass or more than 1.0 part by mass per 100 parts by mass of the toner particles.
According to the invention pertaining to (((10))), there is provided a toner for developing electrostatic images which is less prone to color unevenness compared to a case in which the inorganic particles (B) contain silica particles (B) other than silica particles (A) and strontium titanate particles, and the content of the strontium titanate particles is less than 0.1 part by mass or more than 1.0 part by mass per 100 parts by mass of the toner particles.
According to the invention related to ((12)), there is provided a toner for developing electrostatic images which is less prone to color unevenness, compared to a case in which the surface coverage rate Ca of the toner particles by the silica particles (A) and the surface coverage rate Cb of the toner particles by the inorganic particles (B) do not satisfy the relationship 0.20≦Ca/(Ca+Cb)≦0.75.
According to the invention related to ((13))), there is provided a toner for developing electrostatic images which is less prone to color unevenness, compared to when the surface coverage Ca of the toner particles by the silica particles (A) is less than 10% or exceeds 60%.
According to the invention related to ((14))), there is provided a toner for developing electrostatic images which is less prone to color unevenness, as compared with a case in which the ratio Da/Db of the average primary particle size Da of the silica particles (A) to the average primary particle size Db of the inorganic particles (B) is less than 1 or exceeds 10.

According to the invention according to ((18))), in silica particles having a nitrogen element-containing compound containing molybdenum element externally added to toner particles, the net intensity of molybdenum element measured by fluorescent X-ray analysis. Provided is an electrostatic image developer that is less likely to cause color unevenness than when the ratio N _Mo /N _Si of N _Mo and the net strength N _Si of the silicon element is less than 0.035 or more than 0.45. .
According to the invention according to ((19))), in silica particles having a nitrogen element-containing compound containing molybdenum element externally added to toner particles, the net intensity of molybdenum element measured by fluorescent X-ray analysis A toner cartridge in which color unevenness is less likely to occur is provided than when the ratio N _Mo /N _Si of N _Mo and the net strength N _Si of the silicon element is less than 0.035 or more than 0.45.
According to the invention according to ((20))), in silica particles having a nitrogen element-containing compound containing molybdenum element externally added to toner particles, the net intensity of molybdenum element measured by fluorescent X-ray analysis A process in which color unevenness is less likely to occur compared to the case of applying an electrostatic image developer in which the ratio N _Mo /N _Si of N _Mo and the net strength of silicon element N _Si is less than 0.035 or more than 0.45. A cartridge is provided.
According to the invention according to ((21))), in silica particles having a nitrogen element-containing compound containing molybdenum element externally added to toner particles, the net intensity of molybdenum element measured by fluorescent X-ray analysis. Color unevenness is less likely to occur in images than when using _{an electrostatic charge image developer in which the ratio N Mo /} N _Si of N _Mo and the net strength of silicon element is less than 0.035 or more than 0.45. A forming device is provided.
According to the invention according to (((22))), in silica particles having a nitrogen element-containing compound containing molybdenum element externally added to toner particles, the net intensity of molybdenum element measured by fluorescent X-ray analysis Color unevenness is less likely to occur in images than when using _{an electrostatic charge image developer in which the ratio N Mo /} N _Si of N _Mo and the net strength of silicon element is less than 0.035 or more than 0.45. A method of forming is provided.

1Y, 1M, 1C, 1K photoreceptor (an example of image carrier)
2Y, 2M, 2C, 2K Charging roll (an example of charging means)
3 Exposure device (an example of electrostatic image forming means)
3Y, 3M, 3C, 3K Laser beam 4Y, 4M, 4C, 4K Developing device (an example of developing means)
5Y, 5M, 5C, 5K Primary transfer roll (an example of primary transfer means)
6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt (an example of intermediate transfer body)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
28 Fixing device (an example of fixing means)
30 Intermediate transfer member cleaning device P Recording paper (an example of recording medium)
107 Photoreceptor (an example of an image carrier)
108 Charging roll (an example of charging means)
109 Exposure device (an example of electrostatic image forming means)
111 Developing device (an example of developing means)
112 Transfer device (an example of transfer means)
113 Photoconductor cleaning device (an example of cleaning means)
115 Fixing device (an example of fixing means)
116 Mounting rail 117 Housing 118 Opening for exposure 200 Process cartridge 300 Recording paper (an example of recording medium)

Claims (22)

Toner particles;
silica particles (A) containing a nitrogen-containing compound containing molybdenum, which is externally added to the toner particles;
and inorganic particles (B) other than the silica particles (A) that are externally added to the toner particles,
The silica particles (A) have a ratio _NMo / _NSi of a net intensity NMo of molybdenum element to _a net intensity _NSi of silicon element, which is measured by fluorescent X-ray analysis, of 0.035 or more and 0.45 or less;
The inorganic particles (B) have an average primary particle size of 10 nm or more and 80 nm or less.
Toner for developing electrostatic images. The toner for developing an electrostatic image according to claim 1, wherein the ratio N _Mo /N _Si of the silica particles (A) is 0.05 or more and 0.30 or less. When the overall circularity of the silica particles (A) and the inorganic particles (B) externally added to the toner particles is measured, the circularity distribution has at least two peaks, and the circularity exceeds 0.88. The toner for developing an electrostatic image according to claim 1, wherein the toner has at least one peak in a region and has at least one peak in a region having a circularity of 0.88 or less. The toner for developing electrostatic images according to claim 1, wherein the inorganic particles (B) include silica particles (B) other than the silica particles (A). The toner for developing an electrostatic image according to claim 1, wherein the inorganic particles (B) include titanium compound particles. The toner for developing electrostatic images according to claim 1, wherein the inorganic particles (B) contain strontium titanate particles. The toner for developing an electrostatic image according to claim 1, wherein the inorganic particles (B) include silica particles (B) other than the silica particles (A) and titanium compound particles. The toner for developing an electrostatic image according to claim 7, wherein the content of the titanium compound particles is 0.1 parts by mass or more and 1.0 parts by mass or less based on 100 parts by mass of the toner particles. The toner for developing an electrostatic image according to claim 1, wherein the inorganic particles (B) contain silica particles (B) other than the silica particles (A) and strontium titanate particles. The toner for developing an electrostatic image according to claim 9, wherein the content of the strontium titanate particles is 0.1 parts by mass or more and 1.0 parts by mass or less based on 100 parts by mass of the toner particles. The toner for developing an electrostatic image according to claim 1, wherein the inorganic particles (B) have a volume resistivity of 1.0×10 ¹⁴ Ω·cm or more and 1.0×10 ¹⁷ Ω·cm or more. The toner for developing electrostatic images according to claim 1, wherein the surface coverage rate Ca of the toner particles by the silica particles (A) and the surface coverage rate Cb of the toner particles by the inorganic particles (B) satisfy the relationship 0.20≦Ca/(Ca+Cb)≦0.75. The toner for developing an electrostatic image according to claim 12, wherein the surface coverage Ca of the toner particles by the silica particles (A) is 10% or more and 60% or less. The toner for developing electrostatic images according to claim 1, wherein the ratio Da/Db of the average primary particle diameter Da of the silica particles (A) to the average primary particle diameter Db of the inorganic particles (B) is 1 or more and 10 or less. The nitrogen element-containing compound containing the molybdenum element is at least one selected from the group consisting of a quaternary ammonium salt containing the molybdenum element, and a mixture of a quaternary ammonium salt and a metal oxide containing the molybdenum element. The toner for developing an electrostatic image according to claim 1. The toner for developing electrostatic images according to claim 1, wherein the silica particles (A) are silica particles having a coating structure made of a reaction product of a silane coupling agent and a nitrogen-containing compound containing the molybdenum element attached to the coating structure. The toner for developing an electrostatic image according to claim 16, wherein the silane coupling agent contains an alkyltrialkoxysilane. An electrostatic image developer comprising the toner for developing an electrostatic image according to any one of claims 1 to 17. Containing the electrostatic image developing toner according to any one of claims 1 to 17,
A toner cartridge that can be attached to and removed from an image forming apparatus. a developing unit that contains the electrostatic image developer according to claim 18 and develops an electrostatic image formed on a surface of an image carrier into a toner image by using the electrostatic image developer,
A process cartridge that is detachably attached to an image forming apparatus. an image holder;
Charging means for charging the surface of the image carrier;
an electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means containing the electrostatic image developer according to claim 18, and developing an electrostatic image formed on the surface of the image carrier as a toner image by the electrostatic image developer;
a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
a fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising: a charging step of charging the surface of the image carrier;
an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier;
a developing step of developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer according to claim 18;
a transfer step of transferring the toner image formed on the surface of the image carrier onto a surface of a recording medium;
a fixing step of fixing the toner image transferred onto the surface of the recording medium;
The image forming method according to claim 1,