JP2021135468A - Electrostatic charge image developer, process cartridge, image forming apparatus, and image forming method - Google Patents

Abstract

To provide an electrostatic charge image developer that prevents the generation of color stripes in an image that is formed after images with low image density are continuously output and the developer is stored in a high temperature and high humidity environment for a long period.SOLUTION: An electrostatic charge image developer has: a toner that has toner particles including an inorganic pigment containing metal atoms and an external additive attached to the surface of each of the toner particles; and a carrier that has magnetic particles and a resin layer covering each of the magnetic particles and including inorganic particles, wherein the average particle diameter of the inorganic particles is 5 nm or more and 90 nm or less and the average thickness of the resin layers is 0.6 μm or more and 1.4 μm or less, and when its surface is three-dimensionally analyzed, the ratio of a surface area B to a plan view area A (B/A) is 1.020 or more and 1.110 or less.SELECTED DRAWING: None

Description

The present invention relates to an electrostatic charge image developer, a process cartridge, an image forming apparatus, and an image forming method.

Patent Document 1 has toner particles containing a binder resin and a white pigment, and the content of the white pigment with respect to the entire toner particles is 10% by mass or more and 50% by mass or less, and the white pigment present in the toner particles. In the particle size distribution of the maximum toner diameter of the particles, the proportion of white pigment particles having a maximum toner diameter of 200 nm or more and less than 400 nm is 50% or more of the total, and the frequency is such that the maximum toner diameter is 500 nm or more and less than 650 nm. A toner for static charge image development having a larger maximum frequency when the maximum ferret diameter is 650 nm or more and less than 1000 nm is disclosed as compared with the minimum value.

Patent Document 2 has toner particles containing a binder resin and a white pigment, and develops an electrostatic charge image in which the mode and skewness in the distribution of the uneven distribution of the white pigment in the cross-sectional observation of the toner particles are set in a specific range. Toner for use is disclosed.

Japanese Unexamined Patent Publication No. 2018-066903 JP-A-2018-040952

Since toner particles containing an inorganic pigment containing a metal atom (hereinafter, also referred to as "metal-containing inorganic pigment") have a large specific gravity, the collision energy during stirring in the developing means tends to be large, and the external additive is the toner particles. Easy to be buried in the surface. Further, in a high temperature and high humidity environment (for example, in an environment of a temperature of 28.5 ° C. and a humidity of 85%), moisture is present on the surface of the toner particles due to the influence of polarization of the metal-containing inorganic pigment arranged near the surface of the toner particles. Is easy to adhere. Therefore, the fluidity of the toner is reduced due to the burial of the external additive and the attached moisture, and the toner is formed after being stored for a long period of time in a high temperature and high humidity environment (for example, stored at a temperature of 40 ° C. and a humidity of 90% for 17 hours). Color streaks may occur in the image due to toner clogging in the developing means.

In the present invention, the toner particles contain a metal-containing inorganic pigment, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, the average thickness of the resin layer exceeds 0.6 μm or 1.4 μm, or the ratio B. Compared to the case where / A is less than 1.020 or more than 1.110, the occurrence of color streaks in the image formed after continuously outputting images with low image density and then storing them in a high temperature and high humidity environment for a long period of time. An object of the present invention is to provide a static charge image developer that is suppressed.

Means for solving the above problems include the following aspects.

<1> Toner having toner particles containing an inorganic pigment containing a metal atom and an external additive adhering to the surface of the toner particles, and
It has magnetic particles and a resin layer that covers the magnetic particles and contains inorganic particles. The average particle size of the inorganic particles is 5 nm or more and 90 nm or less, and the average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less. A carrier having a ratio B / A of the plane view area A to the surface area B of 1.020 or more and 1.110 or less when the surface is three-dimensionally analyzed.
Static charge image developer.

<2> The electrostatic charge image developer according to <1>, wherein the ratio B / A is 1.020 or more and 1.090 or less.
<3> The electrostatic charge image developer according to <2>, wherein the ratio B / A is 1.030 or more and 1.060 or less.
<4> The electrostatic charge image developer according to any one of <1> to <3>, wherein the average particle size of the inorganic particles is 5 nm or more and 70 nm or less.
<5> The electrostatic charge image developer according to <4>, wherein the average particle size of the inorganic particles is 5 nm or more and 50 nm or less.
<6> The electrostatic charge image developer according to any one of <1> to <5>, wherein the average thickness of the resin layer is 0.8 μm or more and 1.2 μm or less.
<7> The electrostatic charge image developer according to any one of <1> to <6>, wherein the inorganic particles are silica particles.

<8> The electrostatic charge image developer according to any one of <1> to <7>, wherein the average particle size of the inorganic pigment is 150 nm or more and 500 nm or less.
<9> The static charge according to any one of <1> to <8>, wherein the area ratio of the convex portion due to the inorganic pigment on the surface of the toner particles is 0.30% or more and 5.00% or less. Image developer.
<10> The electrostatic charge image according to any one of <1> to <9>, wherein the average height of the convex portion due to the inorganic pigment on the surface of the toner particles is 0.05 μm or more and 0.30 μm or less. Developer.
<11> The electrostatic charge image developer according to any one of <1> to <10>, wherein the inorganic pigment contains at least one selected from the group consisting of elemental metals, alloys, and metal oxides.

<12> The electrostatic charge image according to any one of <1> to <11>, wherein the average particle size of the inorganic particles is 0.01 times or more and 0.6 times or less of the average particle size of the inorganic pigment. Developer.

<13> The electrostatic charge image developer according to any one of <1> to <12> is contained, and the electrostatic charge image formed on the surface of the image holder by the electrostatic image developer is a toner image. Equipped with a developing means to develop as
A process cartridge that is attached to and detached from the image forming device.
<14> Image holder and
The charging means for charging the surface of the image holder and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
The electrostatic charge image developer according to any one of <1> to <12> is contained, and the electrostatic charge image developer formed on the surface of the image holder is developed as a toner image. Development means and
A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, and
A fixing means for fixing the toner image transferred to the surface of the recording medium, and
An image forming apparatus comprising.
<15> A charging process that charges the surface of the image holder,
A static charge image forming step of forming a static charge image on the surface of the charged image holder, and
A developing step of developing an electrostatic charge image formed on the surface of the image holder as a toner image by using the electrostatic charge image developing agent according to any one of <1> to <12>.
A transfer step of transferring a toner image formed on the surface of the image holder to the surface of a recording medium, and
A fixing step of fixing the toner image transferred to the surface of the recording medium, and
An image forming method having.

According to the invention according to <1>, <7>, or <11>, the toner particles contain a metal-containing inorganic pigment, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, and the average of the resin layers. Compared to the case where the thickness is less than 0.6 μm or more than 1.4 μm, or the ratio B / A is less than 1.020 or more than 1.110, after continuously outputting low image density images, low image density images are displayed. Provided is a static charge image developer in which the generation of color streaks in an image formed after continuous output and storage in a high temperature and high humidity environment for a long period of time is suppressed.

According to the invention according to <2>, as compared with the case where the ratio B / A is less than 1.020 or more than 1.090, images with low image density are continuously output and then stored for a long period of time in a high temperature and high humidity environment. Provided is a static charge image developer in which the generation of color streaks in the image formed after the process is suppressed.
According to the invention according to <3>, as compared with the case where the ratio B / A is less than 1.030 or more than 1.060, images with low image density are continuously output and then stored for a long period of time in a high temperature and high humidity environment. Provided is a static charge image developer in which the generation of color streaks in the image formed after the process is suppressed.
According to the invention according to <4>, as compared with the case where the average particle size of the inorganic particles contained in the resin layer of the carrier is more than 70 nm, after continuously outputting images having a low image density, it is longer in a high temperature and high humidity environment. Provided is a static charge image developer in which the generation of color streaks in an image formed after storage for a period of time is suppressed.
According to the invention according to <5>, as compared with the case where the average particle size of the inorganic particles contained in the resin layer of the carrier is more than 50 nm, after continuously outputting images having a low image density, it is longer in a high temperature and high humidity environment. Provided is a static charge image developer in which the generation of color streaks in an image formed after storage for a period of time is suppressed.
According to the invention according to <6>, as compared with the case where the average thickness of the resin layer is less than 0.8 μm or more than 1.2 μm, images with low image density are continuously output, and then for a long period of time in a high temperature and high humidity environment. Provided is a static charge image developer in which the generation of color streaks in an image formed after storage is suppressed.

According to the invention according to <8>, even if the average particle size of the metal-containing inorganic pigment is 150 nm or more and 500 nm or less, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm and the average thickness of the resin layer. Is less than 0.6 μm or more than 1.4 μm, or the ratio B / A is less than 1.020 or more than 1.110. Provided is a static charge image developer in which the generation of color streaks in an image formed after storage for a period of time is suppressed.
According to the invention according to <9>, even if the area ratio of the convex portion on the surface of the toner particles is 0.30% or more and 5.00% or less, the average particle size of the inorganic particles contained in the resin layer of the carrier is After continuously outputting images with lower image density than when the ratio is over 90 nm, the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm, or the ratio B / A is less than 1.020 or more than 1.110. Provided is a static charge image developer in which the generation of color streaks in an image formed after long-term storage in a high temperature and high humidity environment is suppressed.
According to the invention according to <10>, even if the average height of the convex portion on the surface of the toner particles is 0.05 μm or more and 0.30 μm or less, the average particle size of the inorganic particles contained in the resin layer of the carrier is 90 nm. After continuously outputting images with lower image density than when the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm, or the ratio B / A is less than 1.020 or more than 1.110. Provided is a static charge image developer in which the generation of color streaks in an image formed after long-term storage in a high temperature and high humidity environment is suppressed.

According to the invention according to <12>, compared to the case where the average particle size of the inorganic particles is more than 0.6 times the average particle size of the inorganic pigment, after continuously outputting images having a low image density, a high temperature and high humidity environment Provided is a static charge image developer in which the generation of color streaks in an image formed after long-term storage underneath is suppressed.

According to the invention according to <13>, the toner particles contain a metal-containing inorganic pigment, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, and the average thickness of the resin layer is less than 0.6 μm or 1. Compared to the case where an electrostatic charge image developer having a ratio of more than 4 μm or a ratio B / A of less than 1.020 or more than 1.110 is applied, images with low image density are continuously output and then longer in a high temperature and high humidity environment. A process cartridge is provided in which the occurrence of color streaks in an image formed after storage for a period of time is suppressed.
According to the invention according to <14>, the toner particles contain a metal-containing inorganic pigment, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, and the average thickness of the resin layer is less than 0.6 μm or 1. Compared to the case where an electrostatic charge image developer having a ratio of more than 4 μm or a ratio B / A of less than 1.020 or more than 1.110 is applied, images with low image density are continuously output, and then the image is longer in a high temperature and high humidity environment. An image forming apparatus is provided in which the occurrence of color streaks in an image formed after storage for a period of time is suppressed.
According to the invention according to <15>, the toner particles contain a metal-containing inorganic pigment, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, and the average thickness of the resin layer is less than 0.6 μm or 1. Compared to the case where an electrostatic charge image developer having a ratio of more than 4 μm or a ratio B / A of less than 1.020 or more than 1.110 is applied, images with low image density are continuously output, and then the image is longer in a high temperature and high humidity environment. Provided is an image forming method in which the occurrence of color streaks in an image formed after storage for a period of time is suppressed.

It is a schematic block diagram which shows an example of the image forming apparatus which concerns on this embodiment. It is a schematic block diagram which shows an example of the process cartridge attached to and detached from the image forming apparatus which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described. These explanations and examples illustrate the embodiments and do not limit the scope of the embodiments.

The numerical range indicated by using "~" in the present specification indicates a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively.

In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. good. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

In the present specification, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. ..

When the embodiment is described in the present specification with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Further, the size of the members in each figure is conceptual, and the relative relationship between the sizes of the members is not limited to this.

In the present specification, each component may contain a plurality of applicable substances. When referring to the amount of each component in the composition in the present specification, if a plurality of substances corresponding to each component are present in the composition, the plurality of species present in the composition unless otherwise specified. Means the total amount of substances in.

In the present specification, a plurality of types of particles corresponding to each component may be contained. When a plurality of particles corresponding to each component are present in the composition, the particle size of each component means a value for a mixture of the plurality of particles present in the composition unless otherwise specified.

As used herein, "(meth) acrylic" means at least one of acrylic and methacryl, and "(meth) acrylate" means at least one of acrylate and methacrylate.

[Static charge image developer]
The electrostatic charge image developer (hereinafter, also referred to as “developer”) according to the present embodiment is a toner particle containing an inorganic pigment containing a metal atom (metal-containing inorganic pigment) and an external additive adhering to the surface of the toner particle. It has a toner having the above, magnetic particles, and a resin layer containing the inorganic particles coated with the magnetic particles, and the average particle size of the inorganic particles is 5 nm or more and 90 nm or less, and the average thickness of the resin layer is 0. It has a carrier having a ratio B / A of 6 μm or more and 1.4 μm or less and a ratio B / A of the plane view area A and the surface area B of 1.020 or more and 1.110 or less when the surface is three-dimensionally analyzed.

In the present embodiment, the inorganic particles contained in the resin layer of the carrier are inorganic particles other than carbon black.

In the present embodiment, the average particle size of the inorganic particles contained in the resin layer in the carrier and the average thickness of the resin layer are determined by the following methods.
The carrier is embedded in epoxy resin and cut with a microtome to prepare a carrier cross section. An SEM image obtained by capturing a carrier cross section with a scanning electron microscope (SEM) is taken into an image processing analysis apparatus and image analysis is performed. 100 inorganic particles (primary particles) in the resin layer are randomly selected, the equivalent circle diameter (nm) of each is calculated, and arithmetically averaged, and this is taken as the average particle size (nm) of the inorganic particles. That is, the average particle size of the inorganic particles is the number average particle size.
In addition, the thickness (μm) of the resin layer was measured at 10 points per particle of the carrier at random, and then 100 carriers were measured and all were arithmetically averaged, which was the average thickness (μm) of the resin layer. And.

In the present embodiment, the ratio B / A in the carrier is an index for evaluating the surface roughness. The ratio B / A is obtained by the following method as an example.
As a device for three-dimensionally analyzing the surface of the carrier, a scanning electron microscope having four secondary electron detectors (for example, an electron beam three-dimensional roughness analyzer ERA-8900FE manufactured by Elionix Co., Ltd.) is used for analysis as follows. I do.
The surface of one carrier particle is enlarged 5000 times. The interval between the measurement points is 0.06 μm, 400 points are taken in the long side direction and 300 points are taken in the short side direction, and a region of 24 μm × 18 μm is measured to obtain three-dimensional image data.
For 3D image data, the limit wavelength of the spline filter (frequency selection filter using the spline function) is set to 12 μm to remove wavelengths with a period of 12 μm or more, thereby removing the waviness component of the carrier surface and the roughness. Extract the components and obtain a roughness curve.
Furthermore, the cutoff value of the Gaussian high-pass filter (frequency selection filter using the Gaussian function) is set to 2.0 μm to remove wavelengths with a period of 2.0 μm or more, thereby, from the roughness curve after spline filtering. The wavelength corresponding to the convex portion of the magnetic particles exposed on the carrier surface is removed to obtain a roughness curve from which wavelength components having a period of 2.0 μm or more are removed.
From the three-dimensional roughness curve data after the filtering process obtains the surface area of the region of the central portion 12 [mu] m × 12 [mu] m (the plan view area ^{A = 144μm 2) B (μm} 2), determining the ratio B / A. The ratio B / A is calculated for each of the 100 carriers and arithmetically averaged.

According to the developer of the present embodiment, the generation of color streaks in the image is suppressed. The reason is not clear, but it is presumed as follows.

Since the toner particles containing the metal-containing inorganic pigment have a large specific gravity, the collision energy at the time of stirring in the developing means tends to be large. Then, when the low-density image is continuously formed, the toner is stirred together with the carrier for a long period of time in a state where the toner in the developing means is hardly replaced, so that the external additive is easily embedded in the surface of the toner particles. When the external additive is embedded in the surface of the toner particles, it is difficult to obtain the effect of improving the fluidity of the toner by the external additive, and the fluidity of the toner may decrease due to an increase in the chances that the toner particles come into contact with each other.
Further, in a high temperature and high humidity environment (for example, in an environment of a temperature of 28.5 ° C. and a humidity of 85%), moisture is present on the surface of the toner particles due to the influence of polarization of the metal-containing inorganic pigment arranged near the surface of the toner particles. Is easy to adhere. Therefore, the fluidity of the toner may decrease due to the influence of the attached moisture.

Then, a developer containing toner having reduced fluidity is stored in the developing means of the image forming apparatus and stored for a long period of time in a high temperature and high humidity environment (for example, stored for 17 hours in an environment of a temperature of 40 ° C. and a humidity of 90%). ), When the operation of the image forming apparatus is started, toner clogging in the developing means may occur due to the aggregation of toner. Specifically, for example, toner clogging (so-called trimmer clogging) may occur between the developer holder and the layer regulating member in the developing means. Then, when toner clogging occurs in the developing means, an image in which color streaks caused by the toner clogging may be obtained may be obtained.

On the other hand, in the present embodiment, the carrier has a resin layer containing inorganic particles having an average particle size of 5 nm or more and 90 nm or less, and the average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less. The ratio B / A is 1.020 or more and 1.110 or less. That is, in the present embodiment, there are fine irregularities on the surface of the carrier.
Therefore, it is considered that the contact with the toner becomes a point contact due to the fine irregularities on the carrier surface, and the contact area becomes smaller, so that the load of collision due to stirring is alleviated and the burial of the external additive is suppressed. Further, it is considered that the bound moisture on the surface of the toner particles is removed by scraping and holding the moisture adhering to the surface of the toner particles due to the fine irregularities on the surface of the carrier.
Then, by suppressing the burial of the external additive and removing the bound moisture, the decrease in the fluidity of the toner is suppressed, and the toner is aggregated when the operation of the image forming apparatus is started after long-term storage in a high temperature and high humidity environment. It is presumed that the occurrence of color streaks in the image due to the toner clogging is suppressed by suppressing the toner clogging of the developing means caused by the toner clogging.
Hereinafter, the toner and the carrier constituting the developer according to the present embodiment will be described in detail.

<Toner>
The toner has toner particles containing an inorganic pigment containing a metal atom (metal-containing inorganic pigment) as a colorant, and an external additive adhering to the surface of the toner particles.

(Toner particles)
The toner particles are composed of, for example, a binder resin, a colorant, a mold release agent, and other additives, if necessary.

-Bound resin-
Examples of the binder resin include styrenes (for example, styrene, parachlorostyrene, α-methylstyrene, etc.) and (meth) acrylic acid esters (for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic acid). n-butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (eg, acrylonitrile, Methacronitrile, etc.), vinyl ethers (eg, vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (eg, ethylene, propylene, butadiene, etc.), etc. Examples thereof include a homopolymer of the above-mentioned monomer and a vinyl-based resin composed of a copolymer obtained by combining two or more kinds 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 rosins, mixtures of these with the vinyl resins, or these. Examples thereof include a graft polymer obtained by polymerizing a vinyl-based monomer in the coexistence.
These binder resins may be used alone or in combination of two or more.

As the binder resin, a polyester resin is suitable.
Examples of the polyester resin include known amorphous polyester resins. As the polyester resin, a crystalline polyester resin may be used in combination with the amorphous polyester resin. However, the crystalline polyester resin may be used in a range of 2% by mass or more and 40% by mass or less (preferably 2% by mass or more and 20% by mass or less) with respect to the total binder resin.

The "crystallinity" of the resin means that the resin has a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC). Specifically, the temperature rise rate is 10 (° C.). / Min) indicates that the half width of the endothermic peak is within 10 ° C.
On the other hand, "amorphous" of the resin means that the half width exceeds 10 ° C., shows a stepwise endothermic amount change, or does not show a clear endothermic peak.

-Amorphous polyester resin Examples of the amorphous polyester resin include a condensed polymer of a polyvalent carboxylic acid and a polyhydric alcohol. As the amorphous polyester resin, a commercially available product may be used, or a synthetic resin may be used.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (for example, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.). , Alicyclic dicarboxylic acid (eg cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acid (eg, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), these anhydrides, or their lower grades (eg, 1 or more carbon atoms). 5 or less) Alkyl ester can be mentioned. Among these, as the polyvalent carboxylic acid, for example, an aromatic dicarboxylic acid is preferable.
As the polyvalent carboxylic acid, a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure may be used in combination with the dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, 1 to 5 carbon atoms) alkyl esters thereof.
The polyvalent carboxylic acid may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include aliphatic diols (eg ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (eg cyclohexanediol, cyclohexanedimethanol, etc.). Hydrogenated bisphenol A, etc.), aromatic diols (for example, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, etc.) can be mentioned. Among these, as the polyhydric alcohol, for example, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.
As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used in combination with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
The polyhydric alcohol may be used alone or in combination of two or more.

The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 65 ° C. or lower.
The glass transition temperature is obtained from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically described in JIS K 7121-1987 "Method for measuring the transition temperature of plastics". It is obtained by the "external glass transition start temperature" of.

The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less.
The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2000 or more and 100,000 or less.
The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.
The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed using a Tosoh GPC / HLC-8120GPC as a measuring device, a Tosoh column / TSKgel SuperHM-M (15 cm), and a THF solvent. The weight average molecular weight and the number average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

The amorphous polyester resin is obtained by a well-known manufacturing method. Specifically, for example, the polymerization temperature is set to 180 ° C. or higher and 230 ° C. or lower, the pressure inside the reaction system is reduced as necessary, and the reaction is carried out while removing water and alcohol generated during condensation.
When the raw material monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a dissolution aid to dissolve the monomer. In this case, the polycondensation reaction is carried out while distilling off the dissolution aid. If there is a monomer with poor compatibility, it is advisable to condense the monomer with poor compatibility with the monomer and the acid or alcohol to be polycondensed in advance, and then polycondensate with the main component. ..

-Crystalline polyester resin Examples of the crystalline polyester resin include a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the crystalline polyester resin, a commercially available product may be used, or a synthetic resin may be used.
Here, since the crystalline polyester resin easily forms a crystal structure, a polycondensate using a polymerizable monomer having a linear aliphatic is preferable to a polymerizable monomer having an aromatic.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (for example, oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonandicarboxylic acid, and 1,10-decandicarboxylic acid. Acids, 1,12-dodecanedicarboxylic acids, 1,14-tetradecandicarboxylic acids, 1,18-octadecanedicarboxylic acids, etc., aromatic dicarboxylic acids (eg, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid) Examples thereof include dibasic acids such as acids), anhydrides thereof, and lower (for example, 1 to 5 carbon atoms) alkyl esters thereof.
As the polyvalent carboxylic acid, a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure may be used in combination with the dicarboxylic acid. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (for example, 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.). Examples thereof include anhydrides or lower (for example, 1 to 5 carbon atoms) alkyl esters thereof.
As the polyvalent carboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids.
The polyvalent carboxylic acid may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include an aliphatic diol (for example, a linear aliphatic diol having 7 or more and 20 or less carbon atoms in the main chain portion). Examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8-. Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18- Examples thereof include octadecanediol and 1,14-eicosanedecanediol. Among these, as the aliphatic diol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable.
As the polyhydric alcohol, a trihydric or higher alcohol having a crosslinked structure or a branched structure may be used in combination with the diol. Examples of trihydric or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like.
The polyhydric alcohol may be used alone or in combination of two or more.

Here, the polyhydric alcohol preferably has an aliphatic diol content of 80 mol% or more, preferably 90 mol% or more.

The melting temperature of the crystalline polyester resin is preferably 50 ° C. or higher and 100 ° C. or lower, more preferably 55 ° C. or higher and 90 ° C. or lower, and further preferably 60 ° C. or higher and 85 ° C. or lower.
The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) by the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121-1987 "Method for measuring transition temperature of plastics".

The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

The crystalline polyester resin can be obtained by a well-known manufacturing method, like the amorphous polyester resin, for example.

The content of the binder resin is, for example, 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 60% by mass or more and 85% by mass or less with respect to the entire toner particles. More preferred.

-Colorant-
The toner particles in the present embodiment contain at least a metal-containing inorganic pigment as a colorant, and may contain other colorants if necessary.

The metal-containing inorganic pigment is not particularly limited as long as it is an inorganic pigment containing at least a metal atom.
The metal-containing inorganic pigment is a pigment other than an organic pigment among pigments containing a metal atom, and may be a simple substance of a metal, an alloy, or a metal oxide. The metal-containing inorganic pigment preferably contains at least one selected from the group consisting of elemental metals, alloys, and metal oxides, more preferably containing metal oxides, and among metal oxides, titanium oxide. It is more preferable to include.
In particular, since titanium oxide has high hydrophilicity, moisture tends to adhere to the surface of toner particles containing titanium oxide as a colorant, but in the present embodiment, since the carrier is used, the bound moisture on the surface of the toner particles is easily removed. , The decrease in toner fluidity due to the binding moisture is suppressed.

Examples of the metal-containing inorganic pigment include white pigments and bright pigments.
Examples of the white pigment include titanium oxide, aluminum hydroxide, satin white, talc, zinc oxide, magnesium oxide, magnesium carbonate, kaolin, aluminosilicate, sericite, bentonite and the like.
Examples of the bright pigment include metal pigments such as aluminum, brass, bronze, nickel, stainless steel, and zinc; mica coated with titanium oxide, yellow iron oxide, and the like; aluminosilicate, basic carbonate, barium sulfate, and titanium oxide. , Fragmentary crystals or plate-like crystals such as bismuth oxychloride; flaky glass powder, metal-deposited flaky glass powder; and the like.

The average particle size of the metal-containing inorganic pigment is, for example, 150 nm or more, preferably 180 nm or more, and more preferably 200 nm or more. When the average particle size of the metal-containing inorganic pigment is 150 nm or more, convex portions due to the metal-containing inorganic pigment are likely to be formed on the surface of the toner particles, and the toner particles make point contact with other particles at the convex portions. Therefore, the decrease in toner fluidity due to the burial of the external additive is suppressed.
The average particle size of the metal-containing inorganic pigment may be 500 nm or less, 450 nm or less, or 400 nm or less. Since the average particle size of the metal-containing inorganic pigment is 500 nm or less, there is an advantage that the structure controllability in the toner particles is excellent.
The average particle size of the metal-containing inorganic pigment is preferably 150 nm or more and 500 nm or less, more preferably 180 nm or more and 450 nm or less, and further preferably 200 nm or more and 400 nm or less.
When the metal-containing inorganic pigment is a bright pigment, the average particle size of the bright pigment may be 3 μm or more and 20 μm or less, 4.5 μm or more and 18 μm or less, and 6 μm or more and 16 μm or less. There may be.
The average particle size of the metal-containing inorganic pigment is determined by the same method as the average particle size of the inorganic particles contained in the resin layer of the carrier.
Specifically, the toner is embedded in an epoxy resin and cut with a microtome to prepare a cross section of toner particles. An SEM image obtained by photographing a cross section of a toner particle with a scanning electron microscope (SEM) is taken into an image processing analysis apparatus and image analysis is performed. 100 metal-containing inorganic pigments (primary particles) in the toner particles are randomly selected, the equivalent circle diameter (nm) of each is calculated, and arithmetically averaged, and this is taken as the average particle size (nm) of the metal-containing inorganic pigment. .. That is, the average particle size of the metal-containing inorganic pigment is the number average particle size.

The content of the metal-containing inorganic pigment may be 1% by mass or more or 5% by mass or more with respect to the entire toner particles. The content of the metal-containing inorganic pigment is preferably 10% by mass or more, more preferably 25% by mass or more, and particularly preferably 32% by mass or more, based on the entire toner particles. In particular, when the content of the metal-containing inorganic pigment is 10% by mass or more, convex portions due to the metal-containing inorganic pigment are likely to be formed on the surface of the toner particles, and the toner particles are pointed at the convex portions with other particles. By contacting, the decrease in toner fluidity due to the burial of the external additive is suppressed.
The content of the metal-containing inorganic pigment may be 70% by mass or less, or 50% by mass or less, based on the entire toner particles. In particular, when the content of the metal-containing inorganic pigment is 50% by mass or less, fog of the image due to charge injection into the toner particles is suppressed.
The content of the metal-containing inorganic pigment is preferably 10% by mass or more and 50% by mass or less, more preferably 25% by mass or more and 50% by mass or less, and preferably 32% by mass or more and 50% by mass or less. More preferred.

Examples of other colorants include inorganic pigments, organic pigments, dyes and the like that do not contain metal atoms.
When the toner particles contain other colorants, the ratio of the metal-containing inorganic pigment to the entire colorant contained in the toner particles is preferably 60% by mass or more, more preferably 80% by mass or more, and 90% by mass. It is more preferably mass% or more.
Other colorants include, for example, carbon black, hanza yellow, benzine yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolon orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmin 6B, and dupon. Various types such as oil red, pyrazolone red, resole red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, calco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, malakite green oxalate, etc. Pigments, aclysin, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane Various dyes such as system, diphenylmethane system, and thiazole system can be mentioned.

The content of the entire colorant is, for example, 10% by mass or more and 50% by mass or less, preferably 25% by mass or more and 50% by mass or less, and 32% by mass or more and 50% by mass or less with respect to the entire toner particles. More preferred.

-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; ester waxes such as fatty acid esters and montanic acid esters. ; And so on. The release agent is not limited to this.

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 the DSC curve obtained by differential scanning calorimetry (DSC) by the "melting peak temperature" described in the method for determining the melting temperature in JIS K 7121-1987 "Method for measuring transition temperature of plastics". ..

The content of the release agent is, for example, 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 with respect to the entire toner particles.

-Other additives-
Examples of other additives include well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in the toner particles as an internal additive.

-Characteristics of toner particles, etc.-
The toner particles may be toner particles having a single layer structure, or may be toner particles having a so-called core-shell structure composed of a core portion (core particles) and a coating layer (shell layer) covering the core portion. You may.
Here, the toner particles having a core-shell structure include, for example, a core portion composed of a binder resin and, if necessary, other additives such as a colorant and a mold release agent, and a binder resin. It is preferably composed of a composed coating layer.

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

The various average particle sizes of the toner particles and various particle size distribution indexes were measured using Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolytic solution was measured using ISOTON-II (manufactured by Beckman Coulter). NS.
At the time of measurement, 0.5 mg or more and 50 mg or less of the measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant. This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolytic solution in which the sample is suspended is dispersed for 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a particle size in the range of 2 μm or more and 60 μm or less is obtained by using a Coulter Multisizer II with an aperture of 100 μm. taking measurement. The number of particles to be sampled is 50,000.
Cumulative distribution of volume and number is drawn from the small diameter side for each particle size range (channel) divided based on the measured particle size distribution, and the cumulative 16% particle size is volume particle size D16v and number particle size. The particle size having D16p and a cumulative 50% is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size having a cumulative number of 84% is defined as the volume particle size D84v and the 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 area ratio of the convex portion due to the metal-containing inorganic pigment on the surface of the toner particles is preferably 0.30% or more and 5.00% or less, and preferably 0.35% or more and 3.00% or less. More preferably, it is 0.40% or more and 1.50% or less.
When the area ratio of the convex portion is 0.30% or more, the toner particles are likely to make point contact with other particles at the convex portion, and the decrease in toner fluidity due to the embedding of the external additive is suppressed. Further, when the area ratio of the convex portion is 5.00% or less, fog of the image due to charge injection into the toner particles is suppressed.
The area ratio of the convex portion is controlled, for example, by adjusting the amount of the surfactant added in the process of manufacturing the toner particles. Further, when the toner particles have a core-shell structure, the area ratio of the convex portion may be controlled by adjusting the thickness of the shell layer.

The area ratio of the convex portion is calculated as follows, for example.
Using a measurement sample in which platinum was vapor-deposited on the toner to be measured for 10 seconds by the vapor deposition method, an acceleration voltage of 6 kV was used with a high-resolution field emission scanning electron microscope (FE-SEM, manufactured by Hitachi High-Tech, Inc., model number: S-4700). Perform SEM observation. The obtained photograph of the surface of the toner particles was image-analyzed, and the ratio (%) of the area of the convex portion due to the metal-containing inorganic pigment to the entire area of the toner particles was obtained and averaged for 100 toner particles. Let it be the "area ratio of the convex portion".

The average height of the convex portion due to the metal-containing inorganic pigment on the surface of the toner particles is preferably 0.05 μm or more and 0.30 μm or less, and more preferably 0.10 μm or more and 0.30 μm or less. It is more preferably 0.15 μm or more and 0.25 μm or less.
When the average height of the convex portion is 0.05 μm or more, the toner particles are likely to make point contact with other particles at the convex portion, and the decrease in toner fluidity due to the embedding of the external additive is suppressed. Further, when the average height of the convex portion is 0.30 μm or less, fog of the image due to charge injection into the toner particles is suppressed.
The average height of the convex portion is controlled, for example, by adjusting the amount of the surfactant added in the process of manufacturing the toner particles.

The average height of the convex portion is calculated as follows, for example.
SEM observation is performed at an acceleration voltage of 2 kV using an electron beam three-dimensional roughness analyzer (manufactured by Elionix Inc., model number: ERA-8900FE) using a measurement sample obtained by vapor deposition of platinum on the toner to be measured for 70 seconds. .. The obtained photograph of the surface of the toner particles was image-analyzed, and the surface roughness of the surface of the toner particles including the convex portion due to the metal-containing inorganic pigment was calculated for 100 toner particles in accordance with JIS B 0601-2001. The value obtained by obtaining and averaging the maximum height Ry (μm) is defined as the “average height of the convex portion”.

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 obtained by (circumferential peripheral length) / (peripheral length) [(circumferential length of a circle having the same projected area as the particle image) / (peripheral length of the particle projected image)]. Specifically, it is a value measured by the following method.
First, a flow-type particle image analyzer (Sysmex) that sucks and collects toner particles to be measured, forms a flat flow, and instantly emits strobe light to capture a particle image as a still image and analyze the particle image. Obtained by FPIA-3000) manufactured by the company. Then, the number of samplings when calculating the average circularity is set to 3500.
When the toner has an external additive, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additive has been removed. ..

(External agent)
Examples of the external additive include inorganic particles. As the inorganic particles, 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 , and the like.

The surface of the inorganic particles as an external additive should be hydrophobized. The hydrophobizing treatment is performed, for example, by immersing the inorganic particles in a hydrophobizing agent. The hydrophobizing agent is not particularly limited, and examples thereof include a silane-based coupling agent, a silicone oil, a titanate-based coupling agent, and an aluminum-based coupling agent. These may be used alone or in combination of two or more.
The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the inorganic particles.

Examples of the external additive include resin particles (resin particles such as polystyrene, polymethylmethacrylate (PMMA), and melamine resin), cleaning activators (for example, metal salts of higher fatty acids typified by zinc stearate, and fluoropolymers). Particles) and the like.

The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less with respect to the toner particles.

(Toner manufacturing method)
Next, a method for producing toner according to this embodiment will be described.
The toner according to the present embodiment can be obtained by externally adding an external additive to the toner particles after producing the toner particles.

The toner particles may be produced by any of a dry production method (for example, a kneading and pulverizing method, etc.) and a wet production method (for example, an agglomeration coalescence method, a suspension polymerization method, a dissolution suspension method, etc.). The method for producing the toner particles is not particularly limited to these production methods, and a well-known production method is adopted.
Among these, it is preferable to obtain toner particles by the aggregation and coalescence method.

Specifically, for example, when the toner particles are produced by the aggregation and coalescence method,
A step of preparing a resin particle dispersion liquid in which resin particles to be a binder resin are dispersed (resin particle dispersion liquid preparation step) and a step of preparing the resin particle dispersion liquid (after mixing other particle dispersion liquids as necessary). (In the dispersion), resin particles (other particles if necessary) are agglomerated to form agglomerated particles (aggregated particle forming step), and the agglomerated particle dispersion in which the agglomerated particles are dispersed is heated. Toner particles are manufactured through a step of fusing and coalescing agglomerated particles to form toner particles (fusing and coalescing step).

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

-Resin particle dispersion liquid preparation process-
First, together with the resin particle dispersion liquid in which the resin particles to be the binder resin are dispersed, for example, a colorant particle dispersion liquid in which the colorant particles are dispersed and a release agent particle dispersion liquid in which the release agent particles are dispersed are prepared. do.

Here, the resin particle dispersion liquid is prepared, for example, by dispersing the resin particles in a dispersion medium with a surfactant.

Examples of the dispersion medium used in the resin particle dispersion liquid include an aqueous medium.
Examples of the aqueous medium include distilled water, water such as 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 salt type, sulfonate type, phosphoric acid ester type and soap type; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol. Examples thereof include nonionic surfactants such as systems, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly mentioned. The nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant.
The surfactant may be used alone or in combination of two or more.

Examples of the method for dispersing the resin particles in the dispersion medium in the resin particle dispersion liquid include general dispersion methods such as a rotary shear homogenizer, a ball mill having a medium, a sand mill, and a dyno mill. Further, depending on the type of the resin particles, the resin particles may be dispersed in the resin particle dispersion liquid by using, for example, a phase inversion emulsification method.
In the phase inversion emulsification method, the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, and a base is added to the organic continuous phase (O phase) to neutralize the resin, and then the aqueous medium is used. A method in which the (W phase) is charged to convert the resin from W / O to O / W (so-called phase inversion) to discontinue the phase, and the resin is dispersed in an aqueous medium in the form of particles. Is.

The volume average particle diameter of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and further preferably 0.1 μm or more and 0.6 μm or less. preferable.
The volume average particle size of the resin particles is determined by using the particle size distribution obtained by the measurement of a laser diffraction type particle size distribution measuring device (for example, manufactured by Horiba Seisakusho, LA-700) with respect to the divided particle size range (channel). , The cumulative distribution is subtracted from the small particle size side for the volume, and the particle size that is cumulatively 50% of all particles is measured as the volume average particle size D50v. The volume average particle diameter of the particles in the other dispersion is also measured in the same manner.

The content of the resin particles contained in the resin particle dispersion is, for example, 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 addition, in the same manner as the resin particle dispersion liquid, for example, a colorant particle dispersion liquid and a release agent particle dispersion liquid are also prepared. That is, regarding the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion liquid, the colorant particles dispersed in the colorant particle dispersion liquid and the release agent particle dispersion liquid are used. The same applies to the disperse of the release agent particles.

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

Specifically, for example, a flocculant is added to the mixed dispersion, the pH of the mixed dispersion is adjusted to acidic (for example, the pH is 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. The particles are heated to a temperature of the glass transition temperature of the resin particles (specifically, for example, the glass transition temperature of the resin particles is -30 ° C or higher and the glass transition temperature is -10 ° C or lower), and the particles dispersed in the mixed dispersion are aggregated. , Form agglomerated particles.
In the agglomerated particle forming step, for example, the mixed dispersion is stirred with a rotary shear homogenizer, the above-mentioned flocculant is added at room temperature (for example, 25 ° C.), and the pH of the mixed dispersion is acidic (for example, pH is 2 or more and 5 or less). ), And if necessary, a dispersion stabilizer may be added, and then the above heating may be performed.

Examples of the flocculant include a surfactant used as a dispersant added to the mixed dispersion, a surfactant having the opposite polarity, an inorganic metal salt, and a divalent or higher metal complex. In particular, when a metal complex is used as the flocculant, the amount of the surfactant used is reduced and the charging characteristics are improved.
If necessary, an additive that forms a complex or a similar bond with the metal ion of the flocculant may be used. As this additive, a chelating agent is preferably used.

Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride and aluminum sulfate, and inorganics such as polyaluminum chloride, polyaluminum hydroxide and calcium polysulfide. Examples include metal salt polymers.
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, iminodic acid (IDA), nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA).
The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of the resin particles.

-Fusion / unification process-
Next, the agglomerated particle dispersion liquid in which the agglomerated particles are dispersed is heated to, for example, a temperature equal to or higher than the glass transition temperature of the resin particles (for example, a temperature 10 to 30 ° C. higher than the glass transition temperature of the resin particles) to obtain the agglomerated particles. Are fused and united to form toner particles.

Toner particles are obtained through the above steps.
After obtaining the agglomerated particle dispersion liquid in which the agglomerated particles are dispersed, the agglomerated particle dispersion liquid and the resin particle dispersion liquid in which the resin particles are dispersed are further mixed, and the resin particles are further added to the surface of the agglomerated particles. The step of aggregating so as to adhere to form the second agglomerated particles and the second agglomerated particle dispersion liquid in which the second agglomerated particles are dispersed are heated to fuse and unite the second agglomerated particles. , Toner particles may be produced through a step of forming toner particles having a core / shell structure.

Here, after the fusion / coalescence step is completed, the toner particles formed in the solution are subjected to a known washing step, solid-liquid separation step, and drying step to obtain toner particles in a dried state.
In the cleaning step, it is preferable to sufficiently perform replacement cleaning with ion-exchanged water from the viewpoint of chargeability. The solid-liquid separation step is not particularly limited, but suction filtration, pressure filtration, or the like may be performed from the viewpoint of productivity. The drying step is also not particularly limited, but from the viewpoint of productivity, freeze-drying, air-flow drying, fluid-drying, vibration-type fluid-drying, and the like may be performed.

Then, the toner according to the present embodiment is produced, for example, by adding an external additive to the obtained dry toner particles and mixing them. The mixing may be carried out by, for example, a V blender, a Henschel mixer, a Ladyge mixer or the like. Further, if necessary, coarse particles of toner may be removed by using a vibration sieving machine, a wind sieving machine, or the like.

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The carrier is a resin-coated carrier having magnetic particles and a resin layer that coats the magnetic particles and contains inorganic particles.

(Magnetic particles)
The magnetic particles are not particularly limited, and known magnetic particles used as the core material of the carrier are applied. Specific examples of the magnetic particles include particles of a magnetic metal such as iron, nickel, and cobalt; particles of a magnetic oxide such as ferrite and magnetite; resin-impregnated magnetic particles obtained by impregnating a porous magnetic powder with a resin; in a resin. Examples thereof include magnetic powder-dispersed resin particles in which magnetic powder is dispersed and blended. Ferrite particles are preferable as the magnetic particles in the present embodiment.

The volume average particle diameter of the magnetic particles is preferably 15 μm or more and 100 μm or less, more preferably 20 μm or more and 80 μm or less, and further preferably 30 μm or more and 60 μm or less.
Here, the volume average particle size means a particle size D50v that is cumulatively 50% from the small diameter side in the volume-based particle size distribution.

The arithmetic mean height Ra (JIS B0601: 2001) of the roughness curve of the magnetic particles is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.2 μm or more and 0.8 μm or less.
The arithmetic mean height Ra of the roughness curve of the magnetic particles is determined by using a surface shape measuring device (for example, "ultra-depth color 3D shape measuring microscope VK-9700" manufactured by Keyence Co., Ltd.) at an appropriate magnification (for example, a magnification of 1000). Observe the magnetic particles at (times), obtain a roughness curve with a cutoff value of 0.08 mm, and extract a reference length of 10 μm from the roughness curve in the direction of the average line. Ra of 100 magnetic particles is arithmetically averaged.

As for the magnetic force of the magnetic particles, the saturation magnetization in a magnetic field of 3000 Oersted is preferably 50 emu / g or more, and more preferably 60 emu / g or more. The saturation magnetization is measured using a vibration sample type magnetic measuring device VSMP10-15 (manufactured by Toei Kogyo Co., Ltd.). The measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement is performed by applying an applied magnetic field and sweeping up to 3000 Oersted. Next, the applied magnetic field is reduced to create a hysteresis curve on the recording paper. Saturation magnetization, remanent magnetization, and holding force are obtained from the curve data.

The volumetric electrical resistance (volume resistivity) of the magnetic particles ^{is preferably 1 × 10 5} Ω · cm or more and 1 × 10 ⁹ Ω · cm or less, and more preferably 1 × 10 ⁷ Ω · cm or more and 1 × 10 ⁹ Ω · cm or less. preferable.
The volumetric electrical resistance (Ω · cm) of the magnetic particles is measured as follows. A layer is formed by flatly placing the object to be measured on the surface of a circular jig on which a 20 cm ^{2 electrode plate is arranged so as to have a thickness of 1 mm or more and 3 mm or less.} The 20 cm ² electrode plate is placed on this to sandwich the layer. In order to eliminate the voids between the objects to be measured, the thickness (cm) of the layer is measured after applying a load of 4 kg on the electrode plate arranged on the layer. Both electrodes above and below the layer are connected to an electrometer and a high voltage power generator. A high voltage is applied to both electrodes so that the electric field becomes 103.8 V / cm, and the current value (A) flowing at this time is read. The measurement environment is a temperature of 20 ° C. and a relative humidity of 50%. The formula for calculating the volumetric electrical resistance (Ω · cm) of the object to be measured is as shown in the formula below.
Formula: R = E × 20 / (I-I ₀ ) / L
In the above formula, R is the volumetric electrical resistance (Ω · cm) of the object to be measured, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at the applied voltage 0V, and L is the current value (A). Represents the thickness (cm) of each layer. The coefficient 20 represents the area of the electrode plate (cm ² ).

(Resin layer)
Resins constituting the resin layer include styrene / acrylic acid copolymers; polyolefin resins such as polyethylene and polypropylene; polystyrene, acrylic resins, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, etc. Polyvinyl-based or polyvinylidene-based resins such as polyvinyl ether and polyvinyl ketone; vinyl chloride / vinyl acetate copolymer; straight silicone resin composed of organosiloxane bonds or modified products thereof; polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, Fluororesin such as polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate; amino resin such as urea / formaldehyde resin; epoxy resin; and the like can be mentioned.

The resin layer preferably contains an alicyclic acrylic resin. As the polymerization component of the alicyclic acrylic resin, a lower alkyl ester of (meth) acrylic acid (for example, a (meth) acrylic acid alkyl ester having an alkyl group having 1 or more and 9 or less carbon atoms) is preferable, and specifically, Examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. These monomers may be used alone or in combination of two or more.
The alicyclic acrylic resin preferably contains cyclohexyl (meth) acrylate as a polymerization component. The content of the monomer unit derived from cyclohexyl (meth) acrylate contained in the alicyclic acrylic resin is preferably 75% by mass or more and 100% by mass or less, preferably 85% by mass or more, based on the total mass of the alicyclic acrylic resin. It is more preferably 100% by mass or less, and further preferably 95% by mass or more and 100% by mass or less.

Examples of the inorganic particles contained in the resin layer include metal oxide particles such as silica, titanium oxide, zinc oxide and tin oxide; metal compound particles such as barium sulfate, aluminum borate and potassium titanate; gold, silver and copper. Metal particles; etc. Among these, silica particles are preferable from the viewpoint of suppressing the ejection of toner and maintaining the transferability of the toner image.

The surface of the inorganic particles may be hydrophobized. Examples of the hydrophobizing agent include known organic silicon compounds having an alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, etc.), and specific examples thereof include an alkoxysilane compound, a siloxane compound, and silazane. Examples include compounds. Among these, the hydrophobizing agent is preferably a silazane compound, preferably hexamethyldisilazane. The hydrophobizing agent may be used alone or in combination of two or more.

As a method for hydrophobizing inorganic particles with a hydrophobizing agent, for example, using supercritical carbon dioxide, the hydrophobizing agent is dissolved in the supercritical carbon dioxide, and the hydrophobizing agent is applied to the surface of the inorganic particles. (For example, spraying or coating) a solution containing a hydrophobizing agent and a solvent that dissolves the hydrophobizing agent is applied to the surface of the inorganic particles in the air, and the hydrophobizing agent is applied to the surface of the inorganic particles. Method of adhering; in the air, a solution containing a hydrophobic treatment agent and a solvent for dissolving the hydrophobic treatment agent is added and held in the inorganic particle dispersion, and then a mixed solution of the inorganic particle dispersion and the solution is maintained. A method of drying the solvent;

The average particle size of the inorganic particles is 5 nm or more and 90 nm or less, preferably 5 nm or more and 70 nm or less, more preferably 5 nm or more and 50 nm or less, and further preferably 8 nm or more and 50 nm or less.
When the average particle size of the inorganic particles is 5 nm or more, it is easy to obtain a filler effect that increases the strength of the resin layer, and peeling of the resin layer when image formation is repeated is suppressed. When the resin layer is peeled off, the exposed area of the magnetic particles on the carrier surface increases, the mechanical load on the toner increases, the external additive is easily buried in the toner particles, and toner aggregation is likely to occur. It is presumed to be. Therefore, it is presumed that toner aggregation is suppressed when the average particle size of the inorganic particles is 5 nm or more.
When the average particle size of the inorganic particles is 90 nm or less, it is difficult for the inorganic particles to desorb from the convex portion of the resin layer, and the peeling of the resin layer when the image formation is repeated is suppressed. Further, when the average particle size of the inorganic particles is 90 nm or less, the unevenness of the carrier surface becomes fine, and it becomes easy to scrape off the water adhering to the surface of the toner particles. Therefore, it is presumed that toner aggregation is suppressed.
The average particle size of the inorganic particles may be controlled by adjusting the size of the inorganic particles used for forming the resin layer.

From the viewpoint of suppressing the decrease in toner fluidity, the average particle size of the inorganic particles is preferably 0.01 times or more and 0.6 times or less the average particle size of the metal-containing inorganic pigment contained in the toner particles. It is more preferably 01 times or more and 0.48 times or less, and further preferably 0.012 times or more and 0.34 times or less.

The content of the inorganic particles contained in the resin layer is preferably 5% by mass or more and 70% by mass or less, more preferably 7% by mass or more and 65% by mass or less, and 10% by mass or more and 60% by mass with respect to the total mass of the resin layer. % Or less is more preferable.

The content of silica particles contained in the resin layer is preferably 5% by mass or more and 70% by mass or less, more preferably 7% by mass or more and 65% by mass or less, and 10% by mass or more and 60% by mass with respect to the total mass of the resin layer. % Or less is more preferable.

The resin layer may contain conductive particles for the purpose of controlling charging and resistance. Examples of the conductive particles include carbon black and conductive particles among the above-mentioned inorganic particles.

Examples of the method for forming the resin layer on the surface of the magnetic particles include a wet manufacturing method and a dry manufacturing method. The wet manufacturing method is a manufacturing method using a solvent that dissolves or disperses the resin constituting the resin layer. On the other hand, the dry manufacturing method is a manufacturing method that does not use the above solvent.

As a wet manufacturing method, for example, a dipping method in which magnetic particles are immersed in a resin liquid for forming a resin layer and coated; a spray method in which a resin liquid for forming a resin layer is sprayed on the surface of the magnetic particles; Examples thereof include a fluidized bed method in which a resin liquid for forming a resin layer is sprayed in a modified state; a kneader coater method in which magnetic particles and a resin liquid for forming a resin layer are mixed in a kneader coater to remove a solvent. These manufacturing methods may be repeated or combined.
The resin liquid for forming a resin layer used in the wet production method is prepared by dissolving or dispersing the resin, inorganic particles and other components in a solvent. The solvent is not particularly limited, and for example, aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; and the like are used.

Examples of the dry manufacturing method include a method of forming a resin layer by heating a mixture of magnetic particles and a resin for forming a resin layer in a dry state. Specifically, for example, magnetic particles and a resin for forming a resin layer are mixed in a gas phase and heated and melted to form a resin layer.

The average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less, preferably 0.8 μm or more and 1.2 μm or less, and more preferably 0.8 μm or more and 1.1 μm or less.
When the average thickness of the resin layer is less than 0.6 μm, the resin layer is easily peeled off when image formation is repeated, the exposed area of magnetic particles on the carrier surface increases, the mechanical stress on the toner increases, and the toner is externally added. It is presumed that the agent is buried in the toner particles and toner aggregation occurs. When the average thickness of the resin layer is more than 1.4 μm, the toner external additive easily adheres to or is buried in the resin layer after being transferred to the resin layer, the amount of the external additive transferred from the toner to the carrier increases, and the toner aggregates. Is presumed to occur.
The average thickness of the resin layer can be controlled by the amount of resin used to form the resin layer, and the larger the amount of resin with respect to the amount of magnetic particles, the thicker the average thickness of the resin layer.

(Characteristics of carrier)
The ratio B / A of the plane view area A to the surface area B when the surface of the carrier is three-dimensionally analyzed is 1.020 or more and 1.110 or less, and 1.020 or more and 1.090 or less. It is preferably 1.030 or more and 1.060 or less, and more preferably 1.060 or less.
When the ratio B / A is 1.020 or more, the carrier surface has fine irregularities, and the contact between the carrier and the toner is a point contact, so that the mechanical load on the toner is alleviated and the toner is externally added. The agent is suppressed from being buried in the toner particles. Further, since the carrier surface has fine irregularities, it becomes easy to scrape off the water adhering to the surface of the toner particles, and it becomes easy to hold the scraped water in the recesses. Therefore, it is presumed that the occurrence of toner aggregation is suppressed.
When the ratio B / A is 1.110 or less, the number of fine irregularities on the carrier surface is not too large, and the height difference of the fine irregularities on the carrier surface is not too large. The agent is less likely to enter the recesses on the surface of the carrier, and the increase in the amount of the external additive transferred from the toner to the carrier is suppressed. Further, since the fine irregularities on the carrier surface are not too dense, it becomes easy to retain the scraped water in the recesses. Therefore, it is presumed that toner aggregation is suppressed.

Since the carrier according to the present embodiment has a ratio B / A of 1.020 or more and 1.110 or less, it tends to suppress a decrease in transferability of the toner image when image formation is repeated for a long period of time. In the carrier according to the present embodiment, inorganic particles are contained in the resin layer, and fine irregularities are appropriately present on the surface. Since the contact between the carrier and the toner is a point contact, the mechanical load on the toner is alleviated and the toner external agent is suppressed from being buried in the toner particles, so that the adhesive force of the toner to the member increases. It becomes difficult. As a result, it is presumed that the transferability of the toner image is maintained well. This phenomenon is remarkable when the image formation on the embossed paper is repeated in a high temperature and high humidity environment (for example, a temperature of 30 ° C. and a relative humidity of 80%).

The ratio B / A can be controlled by manufacturing conditions.
For example, in a manufacturing method in which the kneader coater method is repeated a plurality of times (for example, twice) to form a resin layer stepwise, the mixing time of the particles to be coated and the resin liquid for forming the resin layer is adjusted in the final kneader coater step. Then, the ratio B / A is controlled. The longer the mixing time in the final kneader coater step, the smaller the B / A tends to be.
Alternatively, for example, a production method in which a liquid composition containing inorganic particles (resin may or may not be contained) is applied to the surface of a resin-coated carrier produced by the kneader coater method by a spray method. The ratio B / A is controlled by adjusting the particle size and content of the inorganic particles contained in the liquid composition or the amount of the liquid composition applied to the resin-coated carrier.

The exposed area ratio of the magnetic particles on the carrier surface is preferably 5% or more and 30% or less, more preferably 7% or more and 25% or less, and further preferably 10% or more and 25% or less. The exposed area ratio of the magnetic particles in the carrier can be controlled by the amount of the resin used to form the resin layer, and the larger the amount of the resin with respect to the amount of the magnetic particles, the smaller the exposed area ratio.

The exposed area ratio of the magnetic particles on the carrier surface is a value obtained by the following method.
A target carrier and magnetic particles obtained by removing the resin layer from the target carrier are prepared. Examples of the method of removing the resin layer from the carrier include a method of dissolving the resin component with an organic solvent to remove the resin layer, a method of removing the resin component by heating at about 800 ° C., and a method of removing the resin layer. .. Using the carrier and the magnetic particles as measurement samples, the Fe concentration (atomic%) on the sample surface is quantified by XPS, and (Fe concentration of the carrier) ÷ (Fe concentration of the magnetic particles) × 100 is calculated to obtain the magnetic particles. The exposed area ratio (%).

The volume average particle diameter of the carrier is preferably 10 μm or more and 120 μm or less, more preferably 20 μm or more and 100 μm or less, and further preferably 30 μm or more and 80 μm or less.
Here, the volume average particle size means a particle size D50v that is cumulatively 50% from the small diameter side in the volume-based particle size distribution.

<Mixing ratio of carrier and toner>
The mixing ratio (mass ratio) of the carrier and the toner in the developing agent is preferably carrier: toner = 100: 1 to 100:30, more preferably 100: 3 to 100:20.

[Image forming device, image forming method]
The image forming apparatus according to the present embodiment includes an image holder, a charging means for charging the surface of the image holder, a static charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and an electrostatic charge. A developing means that accommodates an image developer and develops an electrostatic charge image formed on the surface of the image holder as a toner image by the static charge image developer, and a recording medium that records the toner image formed on the surface of the image holder. It is provided with a transfer means for transferring to the surface of the recording medium and a fixing means for fixing the toner image transferred to the surface of the recording medium. Then, as the electrostatic charge image developer, the electrostatic charge image developer according to the present embodiment is applied.

In the image forming apparatus according to the present embodiment, a charging step of charging the surface of the image holder, a static charge image forming step of forming an electrostatic charge image on the surface of the charged image holder, and an electrostatic charge according to the present embodiment. A development step of developing an electrostatic charge image formed on the surface of an image holder as a toner image with an image developer, and a transfer step of transferring a toner image formed on the surface of the image holder to the surface of a recording medium. An image forming method (image forming method according to the present embodiment) having 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 is a direct transfer type apparatus that directly transfers the toner image formed on the surface of the image holder to the recording medium; the toner image formed on the surface of the image holder is transferred to the intermediate transfer body. An intermediate transfer type device that first transfers the toner image to the surface and then secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium; after the toner image is transferred, the surface of the image holder before charging is cleaned. A known image forming apparatus such as a device provided with cleaning means; a device provided with static elimination means for irradiating the surface of the image holder with static elimination light after transfer of the toner image and before charging; is applied.
When the image forming apparatus according to the present embodiment is an intermediate transfer type apparatus, the transfer means transfers, for example, an intermediate transfer body in which a toner image is transferred to the surface and a toner image formed on the surface of the image holder. A configuration having a primary transfer means for primary transfer to the surface of the body and a secondary transfer means for secondary transfer of the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium is applied.

In the image forming apparatus according to the present embodiment, for example, the portion including the developing means may have a cartridge structure (process cartridge) attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge containing the electrostatic charge image developer according to the present embodiment and provided with developing means is preferably used.

The image forming apparatus according to the present embodiment is not particularly limited as long as it uses the developer according to the present embodiment, but for example, the toner contained in the developer according to the present embodiment is used as a white toner (white toner). In addition, an image forming apparatus further using at least one selected from the group consisting of a developer containing yellow toner, a developer containing magenta toner, a developer containing cyan toner, and a developer containing black toner can be mentioned. ..

Hereinafter, an example of the image forming apparatus according to the present embodiment will be shown, but the present invention is not limited thereto. In the following description, the main parts shown in the figure will be described, and the description thereof will be omitted for the others.

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to the present embodiment, and is a diagram showing an image forming apparatus of a 5-unit tandem type and an intermediate transfer type.
The image forming apparatus shown in FIG. 1 is an electrophotograph that outputs images of each color of yellow (Y), magenta (M), cyan (C), black (K), and white (W) based on color-separated image data. The first to fifth image forming units of the method 10Y, 10M, 10C, 10K, and 10W (image forming means) are provided. These image forming units (hereinafter, may be simply referred to as “units”) 10Y, 10M, 10C, 10K, and 10W are arranged side by side at a predetermined distance from each other in the horizontal direction. The units 10Y, 10M, 10C, 10K, and 10W may be process cartridges that are attached to and detached from the image forming apparatus.

An intermediate transfer belt 20 as an intermediate transfer body is extended through each unit above the drawings of each unit 10Y, 10M, 10C, 10K, and 10W. The intermediate transfer belt 20 is provided by being wound around a drive roll 22 arranged apart from each other from the left to the right in the drawing and a support roll 23 in contact with the inner surface of the intermediate transfer belt 20, and the first unit 10Y to the fourth unit 10Y to the fourth. It is designed to run in the direction toward the unit 10K. A force is applied to the support roll 23 in a direction away from the drive roll 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around the support roll 23. Further, an intermediate transfer body cleaning device 21 is provided on the side surface of the image holder of the intermediate transfer belt 20 so as to face the drive roll 22.
Further, the developing devices (development means) 4Y, 4M, 4C, and 4K of each unit 10Y, 10M, 10C, and 10K have yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K, respectively. Toner containing the four colors of toner is supplied.

Since the first to fifth units 10Y, 10M, 10C, 10K, and 10W have the same configuration, operation, and operation, the yellow ones arranged on the upstream side in the traveling direction of the intermediate transfer belt are used here. The first unit 10Y forming the image will be described as a representative.

The first unit 10Y has a photoconductor 1Y that acts as an image holder. Around the photoconductor 1Y, a charging roll (an example of charging means) 2Y that charges the surface of the photoconductor 1Y to a predetermined potential, and the charged surface are exposed by a laser beam based on a color-separated image signal. An exposure device (an example of an electrostatic charge image forming means) 3Y that forms an electrostatic charge image, a developing device (an example of a developing means) 4Y that supplies toner to an electrostatic charge image to develop an electrostatic charge image, and a developed toner image. A primary transfer roll (an example of a primary transfer means) 5Y to be transferred onto the intermediate transfer belt 20 and a photoconductor cleaning device (an example of a cleaning means) 6Y for removing toner remaining on the surface of the photoconductor 1Y after the primary transfer are arranged in order. Has been done.
The primary transfer roll 5Y is arranged inside the intermediate transfer belt 20 and is provided at a position facing the photoconductor 1Y. A bias power supply (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, 5K, and 5W of each unit. Each bias power supply changes the value of the transfer bias applied to each primary transfer roll by control by a control unit (not shown).

Hereinafter, the operation of forming a yellow image in the first unit 10Y will be described.
First, prior to the operation, the surface of the photoconductor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y.
The photoconductor 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 usually has a high resistivity (resistance of a general resin), but has a property that when a laser beam is irradiated, the specific resistance of the portion irradiated with the laser beam changes. Therefore, the surface of the charged photoconductor 1Y is irradiated with a laser beam from the exposure apparatus 3Y according to the image data for yellow sent from the control unit (not shown). As a result, an electrostatic charge image of the yellow image pattern is formed on the surface of the photoconductor 1Y.

The static charge image is an image formed on the surface of the photoconductor 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam from the exposure apparatus 3Y, and the surface of the photoconductor 1Y is charged. This is a so-called negative latent image formed by the flow of the charged charge and the residual charge of the portion not irradiated with the laser beam.
The electrostatic charge image formed on the photoconductor 1Y rotates to a predetermined development position as the photoconductor 1Y travels. Then, at this developing position, the electrostatic charge image on the photoconductor 1Y is developed and visualized as a toner image by the developing device 4Y.

In the developing apparatus 4Y, for example, a static charge image developing agent containing at least a yellow toner and a carrier is housed. The yellow toner is triboelectrically charged by being agitated inside the developing apparatus 4Y, and has a charge having the same polarity (negative electrode property) as the charged charge on the photoconductor 1Y, and is a developer roll (developing agent holder). Example) It is held on. Then, as the surface of the photoconductor 1Y passes through the developing device 4Y, the yellow toner is electrostatically adhered to the statically eliminated latent image portion on the surface of the photoconductor 1Y, and the latent image is developed by the yellow toner. .. The photoconductor 1Y on which the yellow toner image is formed is continuously traveled at a predetermined speed, and the toner image developed on the photoconductor 1Y is conveyed 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 an electrostatic force from the photoconductor 1Y toward the primary transfer roll 5Y acts on the toner image to expose the toner image. The toner image on the body 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (−) of the toner, and is controlled to, for example, + 10 μA by a control unit (not shown) in the first unit 10Y.
On the other hand, the toner remaining on the photoconductor 1Y is removed by the photoconductor cleaning device 6Y and recovered.

The primary transfer bias applied to the primary transfer rolls 5M, 5C, 5K, and 5W after the second unit 10M is also controlled according to the first unit.
In this way, the intermediate transfer belt 20 on which the yellow toner image is transferred in the first unit 10Y is sequentially conveyed through the second to fifth units 10M, 10C, 10K, and 10W, and the toner images of each color are superimposed and multiplexed. Transcribed.

The intermediate transfer belt 20 in which five color toner images are multiplex-transferred through the first to fifth units includes an intermediate transfer belt 20, an opposing roll 24 in contact with the inner surface of the intermediate transfer belt, and an image holding surface of the intermediate transfer belt 20. It leads to a secondary transfer unit composed of a secondary transfer roll (an example of the secondary transfer means) 26 arranged on the side. On the other hand, the recording paper (an example of the recording medium) P is fed through the supply mechanism into 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 opposing roll. It is applied to 24. The transfer bias applied at this time is (-) polarity, which is the same polarity as the polarity (-) of the toner, and the electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, and the transfer bias is applied on the intermediate transfer belt 20. The toner image of is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by the resistance detecting means (not shown) for detecting the resistance of the secondary transfer unit, and is voltage controlled.

After that, the recording paper P is sent to the pressure contact portion (nip portion) of the pair of fixing rolls in the fixing device (an example of the fixing means) 28, and the toner image is fixed on the recording paper P to form the fixing image.

Examples of the recording paper P for transferring the toner image include plain paper used in electrophotographic copying machines, printers, and the like. Examples of the recording medium include an OHP sheet and the like in addition to the recording paper P.
In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper P is also preferably smooth, and for example, coated paper in which the surface of plain paper is coated with resin or the like, art paper for printing, or the like is preferably used. Will be done.

The recording paper P for which the color image has been fixed is carried out toward the ejection unit, and a series of color image forming operations is completed.

<Process cartridge>
The process cartridge according to the present embodiment contains the electrostatic charge image developer according to the present embodiment, and is a developing means for developing the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic charge image developer. It is a process cartridge that is attached to and detached from the image forming apparatus.

The process cartridge according to the present embodiment is not limited to the above configuration, and can be selected from developing means and other means such as an image holder, a charging means, an electrostatic charge image forming means, and a transfer means, if necessary. It may be configured to include at least one of the above.

Hereinafter, an example of the process cartridge according to the present embodiment will be shown, but the present invention is not limited thereto. In the following description, the main parts shown in the figure will be described, and the description thereof will be omitted for the others.

FIG. 2 is a schematic configuration diagram showing a process cartridge according to the present embodiment.
The process cartridge 200 shown in FIG. 2 is provided around the photoconductor 107 (an example of an image holder) and the photoconductor 107 by, for example, a housing 117 provided with a mounting rail 116 and an opening 118 for exposure. The charged roll 108 (an example of the charging means), the developing device 111 (an example of the developing means), and the photoconductor cleaning device 113 (an example of the cleaning means) are integrally combined and held and configured to form a cartridge. There is.
In FIG. 2, 109 is an exposure device (an example of an electrostatic charge image forming means), 112 is a transfer device (an example of a transfer means), 115 is a fixing device (an example of a fixing means), and 300 is a recording paper (an example of a recording medium). Is shown.

Hereinafter, embodiments of the invention will be described in detail with reference to Examples, but the embodiments of the invention are not limited to these Examples. In the following description, unless otherwise specified, "parts" and "%" are based on mass.

In the following description, the volume average particle size means a particle size D50v that is cumulatively 50% from the small diameter side in the volume-based particle size distribution.

[Making toner]
<Preparation of amorphous polyester resin dispersion (A1)>
・ Ethylene glycol: 37 parts ・ Neopentyl glycol: 65 parts ・ 1,9-nonanediol: 32 parts ・ Terephthalic acid: 96 parts Put the above materials in a flask and raise the temperature to 200 ° C over 1 hour in the reaction system. After confirming that the mixture was uniformly stirred, 1.2 parts of dibutyltin oxide was added. The temperature was raised to 240 ° C. over 6 hours while distilling off the generated water, and stirring was continued at 240 ° C. for 4 hours. Amorphous polyester resin (acid value 9.4 mgKOH / g, weight average molecular weight 13,000, Glass transition temperature 62 ° C.) was obtained. The amorphous polyester resin was transferred to an emulsification disperser (Cavitron CD1010, Eurotech Co., Ltd.) in a molten state at a rate of 100 g / min. Separately, dilute ammonia water having a concentration of 0.37% obtained by diluting aqueous reagent ammonia with ion-exchanged water is placed in a tank, and the amorphous polyester resin is heated to 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute. At the same time, it was transferred to an emulsion disperser. The emulsification disperser was operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² , to obtain an amorphous polyester resin dispersion (A1) having a volume average particle size of 160 nm and a solid content of 20% by mass.

<Preparation of crystalline polyester resin dispersion liquid (C1)>
-Decandioic acid: 81 parts-Hexanediol: 47 parts The above materials were placed in a flask, the temperature was raised to 160 ° C over 1 hour, and after confirming that the inside of the reaction system was uniformly stirred, dibutyltin oxide was used. 0.03 copies were added. The temperature was raised to 200 ° C. over 6 hours while distilling off the generated 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 substance was dried at a temperature of 40 ° C./reduced pressure to obtain a crystalline polyester resin (C1) (melting point 64 ° C., weight average molecular weight 15,000).

-Crystalline polyester resin (C1): 50 parts-Anionic surfactant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 2 parts-Ion-exchanged water: 200 parts Heat the above material to 120 ° C. , The homogenizer (Ultratalax T50, IKA) was used for sufficient dispersion, and then the pressure discharge type homogenizer was used for dispersion treatment. When the volume average particle size reached 180 nm, the mixture was recovered to obtain a crystalline polyester resin dispersion (C1) having a solid content of 20% by mass.

<Preparation of release agent particle dispersion liquid (W1)>
-Paraffin wax (HNP-9 manufactured by Nippon Seiwa Co., Ltd.): 100 parts-Anionic surfactant (Neogen RK manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part-Ion exchange water: 350 parts Was mixed and heated to 100 ° C., dispersed using a homogenizer (Ultratarax T50 manufactured by IKA), and then dispersed with a pressure discharge type golin homogenizer to disperse the release agent particles having a volume average particle size of 200 nm. A release agent particle dispersion was obtained. Ion-exchanged water was added to the release agent particle dispersion to adjust the solid content to 20% by mass to obtain a release agent particle dispersion (W1).

<Preparation of colorant particle dispersion liquid (W1)>
To 100 mL of a 1 mol / L titanium tetrachloride aqueous solution, 0.15 mol of glycerin was added, and the mixture was heated at 90 ° C. for 4 hours to form white particles, and then filtered. The obtained white particles were dispersed in 100 mL of ion-exchanged water, 0.4 mol of hydrochloric acid was added, and the mixture was heated again at 90 ° C. for 3 hours. After adjusting the pH to 7 with 0.1N sodium hydroxide, filtration, washing with water, and drying (105 ° C., 12 hours) were carried out to obtain white pigment particles (1), which are titanium dioxide particles. The particle size of the obtained white pigment particles (1) was 250 nm.

-White pigment particles (1): 100 parts-Anionic surfactant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen R): 15 parts-Ion-exchanged water: 400 parts A high-pressure impact disperser that mixes the above materials. A colorant particle dispersion (W1) was prepared by dispersing for about 3 hours using an ultimateizer (HJP30006, manufactured by Sugino Machine Co., Ltd.).
The solid content of the colorant particle dispersion liquid (W1) was 23% by mass.

<Preparation of colorant particle dispersion liquid (W2)>
To 100 mL of a 1 mol / L titanium tetrachloride aqueous solution, 0.15 mol of glycerin was added, and the mixture was heated at 25 ° C. for 1 hour to form white particles, and then filtered. The obtained white particles were dispersed in 100 mL of ion-exchanged water, 0.4 mol of hydrochloric acid was added, and the mixture was heated at 90 ° C. for 4 hours. After adjusting the pH to 7 with 0.1N sodium hydroxide, filtration, washing with water, and drying (105 ° C., 12 hours) were carried out to obtain white pigment particles (2), which are titanium dioxide particles. The particle size of the obtained white pigment particles (2) was 100 nm.
A colorant particle dispersion (W2) was prepared in the same manner as the colorant particle dispersion (W1) except that the white pigment particles (2) were used instead of the white pigment particles (1).
The solid content of the colorant particle dispersion liquid (W2) was 23% by mass.

<Preparation of colorant particle dispersion liquid (W3)>
To 100 mL of a 1 mol / L titanium tetrachloride aqueous solution, 0.15 mol of glycerin was added, and the mixture was heated at 95 ° C. for 7 hours to form white particles, and then filtered. The obtained white particles were dispersed in 100 mL of ion-exchanged water, 0.4 mol of hydrochloric acid was added, and the mixture was heated again at 95 ° C. for 4 hours. After adjusting the pH to 7 with 0.1N sodium hydroxide, filtration, washing with water, and drying (105 ° C., 12 hours) were carried out to obtain white pigment particles (3), which are titanium dioxide particles. The particle size of the obtained white pigment particles (3) was 750 nm.
A colorant particle dispersion (W3) was prepared in the same manner as the colorant particle dispersion (W1) except that the white pigment particles (3) were used instead of the white pigment particles (1).
The solid content of the colorant particle dispersion liquid (W3) was 23% by mass.

<Preparation of toner particles (W1)>
・ Ion exchange water: 200 parts ・ Amorphous polyester resin dispersion liquid (A1): 150 parts ・ Crystalline polyester resin dispersion liquid (C1): 10 parts ・ Detaching agent particle dispersion liquid (W1): 10 parts ・ Colorant Particle dispersion (W1): 20 parts, anionic surfactant (TaycaPower): 2.8 parts

Put the above materials in a round stainless steel flask, add 0.1N nitrate to adjust the pH to 3.5, and then add 2 parts of polyaluminum chloride (manufactured by Oji Paper Co., Ltd., 30% powder). An aqueous solution of polyaluminum chloride dissolved in 30 parts of ion-exchanged water was added. After dispersing at 30 ° C. using a homogenizer (Ultra Tarax T50 manufactured by IKA), the mixture was heated to 45 ° C. in a heating oil bath and maintained until the volume average particle size became 4.9 μm.
Next, 60 parts of the amorphous polyester resin dispersion (A1) was added and held for 30 minutes.
Then, when the volume average particle size was 5.2 μm, 60 parts of the amorphous polyester resin dispersion (A1) was further added and held for 30 minutes.

Subsequently, 20 parts of a 10% NTA (nitrilotriacetic acid) metal salt aqueous solution (Kirest 70, manufactured by Kirest Co., Ltd.) was added, and a 1N sodium hydroxide aqueous solution was added to adjust the pH to 9.0. Next, 1 part of anionic surfactant (TaycaPower) was added and heated to 85 ° C. while continuing stirring, and held for 5 hours. It was then cooled to 20 ° C. at a rate of 20 ° C./min. Then, it was filtered, thoroughly washed with ion-exchanged water, and dried to obtain toner particles (W1) having a volume average particle size of 5.7 μm and an average circularity of 0.971.

Hereinafter, the amorphous polyester resin dispersion liquid (A1) initially charged into the round stainless steel flask is also referred to as "initial amorphous polyester resin dispersion liquid (A1)", and the volume average particle size is 4.9 μm. The amorphous polyester resin dispersion (A1) added after holding up to is also called "first additional amorphous polyester resin dispersion (A1)" and was added when the volume average particle size became 5.2 μm. The amorphous polyester resin dispersion liquid (A1) is also referred to as "second additional amorphous polyester resin dispersion liquid (A1)".

<Making toner (W1)>
100 parts by mass of toner particles (W1) and 1.5 parts by mass of hydrophobic silica particles (RY50, manufactured by Nippon Aerosil Co., Ltd.) were placed in a sample mill and mixed at a rotation speed of 10000 rpm for 30 seconds. Next, the toner (W1) having a volume average particle size of 5.7 μm was obtained by sieving with a vibrating sieve having a mesh size of 45 μm.

<Preparation of toner particles (W2) and toner (W2)>
The amount of the initial amorphous polyester resin dispersion (A1) added was 100 parts, the amount of the first additional amorphous polyester resin dispersion (A1) was 90 parts, and the amount of the second additional amorphous polyester resin dispersion was 90 parts. Toner particles (W2) and toner (W2) were obtained in the same manner as the toner particles (W1) and toner (W1) except that the amount of the liquid (A1) added was changed to 80 parts.

<Preparation of toner particles (W3) and toner (W3)>
The initial amount of the amorphous polyester resin dispersion (A1) added was 180 parts, the amount of the first additional amorphous polyester resin dispersion (A1) added was 60 parts, and the second additional amorphous polyester resin dispersion. Toner particles (W3) and toner (W3) were obtained in the same manner as the toner particles (W1) and toner (W1) except that the amount of the liquid (A1) added was changed to 30 parts.

<Preparation of toner particles (W4) and toner (W4)>
Toner particles (W4) and toner (W4) were obtained in the same manner as the toner particles (W1) and the toner (W1) except that the amount of the anionic surfactant (TaycaPower) added was changed to 1.9 parts. ..

<Preparation of toner particles (W5) and toner (W5)>
Toner particles (W5) and toner (W5) were obtained in the same manner as the toner particles (W1) and toner (W1) except that the amount of anionic surfactant (TaycaPower) added was changed to 3.5 parts. ..

<Preparation of toner particles (W6) and toner (W6)>
The initial amount of the amorphous polyester resin dispersion (A1) added was 80 parts, the amount of the first additional amorphous polyester resin dispersion (A1) added was 100 parts, and the second additional amorphous polyester resin dispersion. Toner particles (W6) and toner (W6) were obtained in the same manner as the toner particles (W1) and toner (W1) except that the amount of the liquid (A1) added was changed to 90 parts.

<Preparation of toner particles (W7) and toner (W7)>
170 parts of the initial amorphous polyester resin dispersion (A1) was added, 90 parts of the first additional amorphous polyester resin dispersion (A1) was added, and the second additional amorphous polyester resin dispersion. Toner particles (W7) and toner (W7) were obtained in the same manner as the toner particles (W1) and toner (W1) except that the amount of the liquid (A1) added was changed to 10 parts.

<Preparation of toner particles (W8) and toner (W8)>
Except that 20 parts of the colorant particle dispersion (W2) was added instead of 20 parts of the colorant particle dispersion (W1), and the amount of the anionic surfactant (TaycaPower) added was changed to 1.5 parts. , Toner particles (W1) and toner (W1) were obtained in the same manner as toner particles (W1) and toner (W1).

<Preparation of toner particles (W9) and toner (W9)>
Toner except that 20 parts of the colorant particle dispersion (W3) was added instead of 20 parts of the colorant particle dispersion (W1) and the amount of the anionic surfactant (TaycaPower) was changed to 4 parts. Toner particles (W9) and toner (W9) were obtained in the same manner as the particles (W1) and toner (W1).

<Preparation of toner particles (W10) and toner (W10)>
Instead of 20 parts of the colorant particle dispersion (W1), 5.7 parts of the colorant particle dispersion (W1) was added, and the amount of the anionic surfactant (TaycaPower) added was 2.8 to 1. Toner particles (W10) and toner (W10) were obtained in the same manner as the toner particles (W1) and the toner (W1) except that the parts were changed to four parts.

<Preparation of toner particles (W11) and toner (W11)>
Similar to the toner particles (W1) and the toner (W1), the toner particles (W11) and Toner (W11) was obtained.

<Preparation of toner particles (W12) and toner (W12)>
Similar to the toner particles (W1) and the toner (W1), the toner particles (W12) and the toner particles (W12) and Toner (W12) was obtained.

<Preparation of toner particles (W13) and toner (W13)>
Similar to the toner particles (W1) and the toner (W1), the toner particles (W13) and the toner particles (W13) and Toner (W13) was obtained.

<Toner measurement>
Regarding the obtained toner, the area ratio of the convex portion due to the white pigment on the surface of the toner particles (“convex portion ratio” in Table 1) and the average particle size of the white pigment (“pigment particle size” in Table 1). , The content of the white pigment with respect to the entire toner particles (“pigment amount” in Table 1), and the average height of the convex portion due to the white pigment on the surface of the toner particles (“convex height” in Table 1). The results obtained by the above-mentioned method are shown in Table 1.

[Creation of carrier]
<Preparation of ferrite particles (1)>
And Fe ₂ O ₃ 1318 parts, was performed and Mn (OH) ₂ 587 parts, was mixed with Mg (OH) ₂ 96 parts of the calcined temperature 900 ° C. and 4 hours. A pre-baked product, 6.6 parts of polyvinyl alcohol, 0.5 part of polycarboxylic acid as a dispersant, and zirconia beads having a media diameter of 1 mm are put into water, and pulverized and mixed with a sand mill to prepare a dispersion liquid. Obtained. The volume average particle size of the particles in the dispersion was 1.5 μm.
The dispersion was used as a raw material and granulated and dried with a spray dryer to obtain granules having a volume average particle size of 37 μm. Next, under an oxygen-nitrogen mixed atmosphere with an oxygen partial pressure of 1%, the main firing was performed at a temperature of 1450 ° C. and 4 hours using an electric furnace, and then heating was performed at a temperature of 900 ° C. and 3 hours in the atmosphere. Fired particles were obtained. The calcined particles were crushed and classified to obtain ferrite particles (1) having a volume average particle diameter of 35 μm. The arithmetic mean height Ra (JIS B0601: 2001) of the roughness curve of the ferrite particles (1) was 0.6 μm.

<Silica particles (1)>
As the silica particles (1), commercially available hydrophobic silica particles (fumed silica particles surface-treated with hexamethyldisilazane, manufactured by Tokuyama Corporation, product name: Leoloseal HM20S, number average particle size 12 nm) were prepared.

<Silica particles (2)>
890 parts of methanol and 210 parts of 9.8% ammonia water were put into a 1.5 L glass reaction vessel equipped with a stirrer, a dropping nozzle and a thermometer and mixed to obtain an alkaline catalyst solution. After adjusting the alkali catalyst solution to 45 ° C., 550 parts of tetramethoxysilane and 180 parts of 7.6% ammonia water were simultaneously added dropwise over 470 minutes with stirring to obtain a silica particle dispersion (A). The silica particles in the silica particle dispersion (A) have a number average particle size of 5 nm and a volume particle size distribution index (particle size D16v that is cumulative 16% from the small diameter side and particle size D84v that is cumulative 84% in the volume-based particle size distribution. The square root of the ratio with (D84v / D16v) ^1/2 ) 1.2.

300 parts of the silica particle dispersion liquid (A) was put into an autoclave equipped with a stirrer, and the stirrer was rotated at a rotation speed of 100 rpm. While continuing the rotation of the stirrer, liquefied carbon dioxide is injected into the autoclave from the carbon dioxide cylinder via the pump, the temperature inside the autoclave is raised by the pump and the pressure is increased by the pump, and the inside of the autoclave is in a supercritical state of 150 ° C. and 15 MPa. And said. By operating the pressure valve, supercritical carbon dioxide was circulated while keeping the inside of the autoclave at 15 MPa, and methanol and water were removed from the silica particle dispersion liquid (A). When the amount of carbon dioxide supplied into the autoclave reached 900 parts, the supply of carbon dioxide was stopped to obtain silica particle powder.

While keeping the inside of the autoclave at 150 ° C. and 15 MPa with a heater and a pump to maintain the supercritical state of carbon dioxide, while continuing the rotation of the autoclave stirrer, 50 parts of hexamethyldisilazane was added to 100 parts of silica particles. The particles were injected into the autoclave by a trainer pump, the temperature inside the autoclave was raised to 180 ° C., and the reaction was carried out for 20 minutes. Then, supercritical carbon dioxide was circulated again in the autoclave to remove excess hexamethyldisilazane. Then, the stirring was stopped, the pressure valve was opened, the pressure in the autoclave was released to atmospheric pressure, and the temperature was lowered to room temperature (25 ° C.). In this way, silica particles (2) surface-treated with hexamethyldisilazane were obtained. The silica particles (2) had a number average particle size of 5 nm.

<Silica particles (3)>
Similar to the preparation of the silica particles (2), however, after adjusting the alkali catalyst solution for preparing the silica particle dispersion liquid (A) to 70 ° C., the amount of tetramethoxysilane and 7.6% aqueous ammonia added dropwise. To 550 parts of tetramethoxysilane and 100 parts of 7.6% aqueous ammonia, the dropping time was changed to 400 minutes, the average number of silica particles in the silica particle dispersion was changed to 90 nm, and hexa. Silica particles (3) surface-treated with methyl disilazane were obtained. The silica particles (3) had a number average particle size of 90 nm.

<Silica particles (4)>
890 parts of methanol and 210 parts of 9.8% aqueous ammonia were added to a 1.5 L glass reaction vessel equipped with a stirrer, a dropping nozzle, and a thermometer and mixed to obtain an alkaline catalyst solution.
After adjusting this alkaline catalyst solution to 47 ° C., 550 parts of tetramethoxysilane and 140 parts of 7.6% ammonia water were simultaneously added dropwise over 450 minutes while stirring, and hydrophilicity having a particle size of 1 nm and a particle size distribution of 1.25 was added. A sex silica particle dispersion (B) was obtained.

Using the silica particle dispersion liquid (B), the silica particles were surface-treated with a siloxane compound in a supercritical carbon dioxide atmosphere as shown below. For the surface treatment, an apparatus equipped with a carbon dioxide cylinder, a carbon dioxide pump, an entrainer pump, an autoclave with a stirrer (capacity 500 ml), and a pressure valve was used.
First, 300 parts of the silica particle dispersion liquid (B) was put into an autoclave with a stirrer (capacity: 500 ml), and the stirrer was rotated at 100 rpm. Then, liquefied carbon dioxide was injected into the autoclave, and the pressure was increased by a carbon dioxide pump while raising the temperature with a heater to bring the inside of the autoclave into a supercritical state at 150 ° C. and 15 MPa. Supercritical carbon dioxide is circulated from the carbon dioxide pump while keeping the inside of the autoclave at 15 MPa with a pressure valve, methanol and water are removed from the silica particle dispersion (B) (solvent removal step), and silica particles (untreated silica particles) are removed. ) Was obtained.

Next, when the distribution amount of supercritical carbon dioxide (integrated amount: measured as the distribution amount of carbon dioxide in the standard state) reached 900 copies, the distribution of supercritical carbon dioxide was stopped.
After that, the temperature was maintained at 150 ° C. by the heater and the pressure was maintained at 15 MPa by the carbon dioxide pump, and the supercritical state of carbon dioxide was maintained in the autoclave. After injecting 100 parts of hexamethyldisilazane (HMDS: manufactured by Yuki Gosei Kogyo Co., Ltd.) as a hydrophobizing agent into an autoclave with an entrainer pump, the reaction was carried out at 180 ° C. for 20 minutes with stirring. Then, supercritical carbon dioxide was circulated again to remove the excess treatment agent solution. After that, stirring was stopped, the pressure valve was opened, the pressure in the autoclave was released to atmospheric pressure, and the temperature was lowered to room temperature (25 ° C.).
As described above, the solvent removing step and the surface treatment with the siloxane compound were sequentially carried out to obtain silica particles (4) which are surface-treated silica particles having a number average particle diameter of 1 nm.

<Silica particles (5)>
As the silica particles (5), commercially available hydrophobic silica particles (silica particles surface-treated with hexamethyldisilazane, manufactured by CABOT, product number: TG-6020N, number average particle size 200 nm) were prepared.

<Preparation of carrier (1)>
-Ferrite particles (1): 100 parts-Cyclohexyl methacrylate / methyl methacrylate copolymer (copolymerization ratio 95 mol: 5 mol): 3 parts-Silica particles (1): 0.7 parts-Toluene 14 parts Of the above materials Among them, cyclohexyl methacrylate / methyl methacrylate copolymer, silica particles (1), toluene and glass beads (diameter 1 mm, same amount as toluene) were put into a sand mill (Kansai Paint Co., Ltd.) and stirred at a rotation speed of 1200 rpm for 30 minutes. , The resin liquid (1) for forming a resin layer. Ferrite particles (1) are put into a vacuum degassing type kneader, and further a resin liquid (1) for forming a resin layer is put into the vacuum degassing type kneader. (1) was coated with a resin to form a resin layer. Next, fine powder and coarse powder were removed with an elbow jet to obtain a carrier (1) which is a resin-coated carrier.

<Preparation of carrier (2)>
A carrier (2) was obtained in the same manner as in the carrier (1) except that the temperature raising and depressurizing time was changed to 60 minutes.

<Preparation of carrier (3)>
A carrier (3) was obtained in the same manner as in the carrier (1) except that the temperature raising and depressurizing time was changed to 15 minutes.

<Preparation of carrier (4)>
Carriers (except that 0.7 parts of silica particles (2) were used instead of 0.7 parts of silica particles (1) and the amount of cyclohexyl methacrylate / methyl methacrylate copolymer added was changed to 3.4 parts. A carrier (4) was obtained in the same manner as in 1).

<Preparation of carrier (5)>
Carrier (1) except that 0.7 parts of silica particles (3) were used instead of 0.7 parts of silica particles (1) and the amount of cyclohexyl methacrylate / methyl methacrylate copolymer added was changed to 2 parts. The carrier (5) was obtained in the same manner as in the above.

<Preparation of carrier (6)>
A carrier (6) was obtained in the same manner as in the carrier (1) except that the temperature raising and depressurizing time was changed to 90 minutes.

<Preparation of carrier (7)>
A carrier (7) was obtained in the same manner as in the carrier (1) except that the temperature raising and depressurizing times were changed to 10 minutes.

<Preparation of carrier (8)>
Use 0.7 parts of silica particles (4) instead of 0.7 parts of silica particles (1), increase and decrease the temperature for 45 minutes, and add cyclohexylmethacrylate / methylmethacrylate copolymer to 3 parts. A carrier (8) was obtained in the same manner as the carrier (1) except for the change.

<Preparation of carrier (9)>
A carrier (9) was obtained in the same manner as in the carrier (1) except that 0.7 part of the silica particles (5) was used instead of 0.7 parts of the silica particles (1).

<Preparation of carrier (10)>
A carrier (10) was obtained in the same manner as in the carrier (1) except that the amount of the cyclohexyl methacrylate / methyl methacrylate copolymer added was changed to 5 parts.

<Preparation of carrier (11)>
A carrier (11) was obtained in the same manner as in the carrier (1) except that the amount of the cyclohexyl methacrylate / methyl methacrylate copolymer added was changed to 1.3 parts.

<Preparation of carrier (12)>
A carrier (12) was obtained in the same manner as the carrier (1) except that the silica particles (1) were not used.

<Measurement of carrier>
Regarding the obtained carriers, the ratio B / A (“ratio B / A” in Tables 2 and 3) and the average particle size of the silica particles contained in the resin layer (“inorganic particle size” in Tables 2 and 3). ”), And the results of determining the average thickness of the resin layer (“thickness” in Tables 2 and 3) by the above method are shown in Tables 2 and 3.

[Preparation of developer]
The carriers shown in Tables 2 and 3 and the toners shown in Tables 2 and 3 are placed in a V-blender at a mixing ratio of carrier: toner = 100:10 (mass ratio) and stirred for 20 minutes, respectively, and white developers are added. Obtained.

[Evaluation of developer]
^{A4 size color paper (Fuji Xerox Co., Ltd., light blue basis weight 64 g / m 2} ) using a modified DocuCenterColor400 (manufactured by Fuji Xerox Co., Ltd.) in an environment with a temperature of 28.5 ° C and a humidity of 85%. Was used, and a test was conducted in which 100,000 images were output over 10 days using an image sample in which a rectangular patch was written so that the image density was 20%. After outputting a total of 100,000 images, the modified machine was shut down and left for a whole day and night (specifically, it was left for 17 hours in an environment of a temperature of 40 ° C. and a humidity of 90%). After that, after printing 7,000 images in one day using an image sample in which a rectangular patch was written so that the image density was 20% in borderless printing mode, the remodeling machine was shut down again and left for a whole day and night (specifically). Was left for 17 hours in an environment with a temperature of 40 ° C. and a humidity of 90%). The next day, the test chart number 5 of the Imaging Society of Japan was output to evaluate the image quality (specifically, the color streaks and the fog were evaluated). The evaluation criteria for each evaluation are as follows, and the results are shown in Tables 2 and 3. The evaluation range was up to C.

<Evaluation criteria for color streaks>
A: There is no problem with image quality.
B: By visual confirmation, slight unevenness due to the developing brush is observed on the developing sleeve, but there is no problem with the image quality.
C: By visual confirmation, unevenness due to the developing brush is observed on the developing sleeve, and slight color streaks are observed.
D: By visual confirmation, unevenness due to the developing brush is observed on the developing sleeve, and clear color streaks are observed.

<Evaluation criteria for fog>
A: The density E of the background part (that is, the non-image part) of the image is less than 0.015, no fog is visually observed, no fog is confirmed by the tape transfer test on the photoconductor, and there is a problem in image quality. No.
B: The density E of the background portion of the image is 0.015 or more and less than 0.03, no fog is visually observed, and a slight fog is confirmed in the tape transfer test on the photoconductor, but there is no problem in image quality. ..
B-: The density E of the background portion of the image is 0.03 or more and less than 0.04, no fog is visually observed, and fog is confirmed in the tape transfer test on the photoconductor, but there is no problem in image quality.
C: The density E of the background portion of the image is 0.04 or more and less than 0.05, no fog is visually observed, and fog is clearly confirmed in the tape transfer test on the photoconductor, but the image quality is within the allowable range. be.
D: When the density E of the background portion of the image is 0.05 or more, fog is visually observed, and clear density unevenness is observed on the image.
The above "density E" is an average value of the densities obtained by measuring 9 points of the non-image portion with an image densitometer (X-Rite 938: manufactured by X-Rite).

As shown in the above table, it can be seen that in the examples, the occurrence of color streaks in the image is suppressed as compared with the comparative examples.

1Y, 1M, 1C, 1K, 1W Photoreceptor (Example of image holder)
2Y, 2M, 2C, 2K, 2W charging roll (an example of charging means)
3Y, 3M, 3C, 3K, 3W exposure equipment (an example of electrostatic charge image forming means)
4Y, 4M, 4C, 4K, 4W developing device (example of developing means)
5Y, 5M, 5C, 5K, 5W primary transfer roll (example of primary transfer means)
6Y, 6M, 6C, 6K, 6W Photoreceptor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K, 8W Toner Cartridge 10Y, 10M, 10C, 10K, 10W Image Forming Unit 20 Intermediate Transfer Belt (Example of Intermediate Transfer)
21 Intermediate transfer body cleaning device 22 Drive roll 23 Support roll 24 Opposing roll 26 Secondary transfer roll (an example of secondary transfer means)
28 Fixing device (an example of fixing means)
P Recording paper (an example of recording medium)
107 Photoreceptor (an example of image holder)
108 Charging roll (an example of charging means)
109 Exposure device (an example of electrostatic charge image forming means)
111 Developing equipment (an example of developing means)
112 Transfer device (an example of transfer means)
113 Photoreceptor 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 (15)

Toner having toner particles containing an inorganic pigment containing a metal atom and an external additive adhering to the surface of the toner particles, and
It has magnetic particles and a resin layer that covers the magnetic particles and contains inorganic particles. The average particle size of the inorganic particles is 5 nm or more and 90 nm or less, and the average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less. A carrier having a ratio B / A of the plane view area A to the surface area B of 1.020 or more and 1.110 or less when the surface is three-dimensionally analyzed.
Static charge image developer. The electrostatic charge image developer according to claim 1, wherein the ratio B / A is 1.020 or more and 1.090 or less. The electrostatic charge image developer according to claim 2, wherein the ratio B / A is 1.030 or more and 1.060 or less. The electrostatic charge image developer according to any one of claims 1 to 3, wherein the average particle size of the inorganic particles is 5 nm or more and 70 nm or less. The electrostatic charge image developer according to claim 4, wherein the average particle size of the inorganic particles is 5 nm or more and 50 nm or less. The electrostatic charge image developer according to any one of claims 1 to 5, wherein the average thickness of the resin layer is 0.8 μm or more and 1.2 μm or less. The electrostatic charge image developer according to any one of claims 1 to 6, wherein the inorganic particles are silica particles. The electrostatic charge image developer according to any one of claims 1 to 7, wherein the average particle size of the inorganic pigment is 150 nm or more and 500 nm or less. The electrostatic charge image developer according to any one of claims 1 to 8, wherein the area ratio of the convex portion caused by the inorganic pigment on the surface of the toner particles is 0.30% or more and 5.00% or less. .. The electrostatic charge image developer according to any one of claims 1 to 9, wherein the average height of the convex portion due to the inorganic pigment on the surface of the toner particles is 0.05 μm or more and 0.30 μm or less. The electrostatic charge image developer according to any one of claims 1 to 10, wherein the inorganic pigment contains at least one selected from the group consisting of a simple substance of a metal, an alloy, and a metal oxide. The electrostatic charge image developer according to any one of claims 1 to 11, wherein the average particle size of the inorganic particles is 0.01 times or more and 0.6 times or less the average particle size of the inorganic pigment. The electrostatic charge image developer according to any one of claims 1 to 12 is contained, and the electrostatic charge image developer formed on the surface of the image holder is developed as a toner image. Equipped with developing means
A process cartridge that is attached to and detached from the image forming device. Image holder and
The charging means for charging the surface of the image holder and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
The electrostatic charge image developer according to any one of claims 1 to 12 is contained, and the electrostatic charge image developer formed on the surface of the image holder is developed as a toner image. Development means and
A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, and
A fixing means for fixing the toner image transferred to the surface of the recording medium, and
An image forming apparatus comprising. The charging process that charges the surface of the image holder,
A static charge image forming step of forming a static charge image on the surface of the charged image holder, and
A developing step of developing an electrostatic charge image formed on the surface of the image holder as a toner image by using the electrostatic charge image developer according to any one of claims 1 to 12.
A transfer step of transferring a toner image formed on the surface of the image holder to the surface of a recording medium, and
A fixing step of fixing the toner image transferred to the surface of the recording medium, and
An image forming method having.

Images