JP2021135469A - Carrier for electrostatic charge image development, electrostatic charge image developer, process cartridge, image forming apparatus, and image forming method - Google Patents

Abstract

To provide a carrier for electrostatic charge image development that prevents spew of toner.SOLUTION: A carrier for electrostatic charge image development 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 1.100 or less.SELECTED DRAWING: None

Description

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

Patent Document 1 includes magnetic core material particles and a coating layer that covers the surface of the core material particles. The coating layer contains two or more types of inorganic fine particles, and at least two or more types of inorganic fine particles. 1 and having a Tsugashirube conductivity are inorganic fine particles a having a peak particle diameter of 300 nm to 1000 nm, (BET specific surface area of the carrier - BET specific surface area of the core particle) is 1.10m ² /g~1.90m ² Carriers for electrostatic latent image developers at / g are disclosed.
Patent Document 2 describes a carrier for an electrostatic charge image developer having a coating layer containing a binder resin and fine particles on the core material, and the area ratio of the portion where the core material is exposed on the surface of the carrier particles is 0.1%. More than 5.0% or less, the area of the maximum exposed part among the exposed parts of the core material is 0.03% or less of the surface area of the core material, and the fine particles are 100 parts by weight or more and 500 parts by weight with respect to 100 parts by weight of the binder resin. A carrier for developing an electrostatic latent image containing a portion or less is disclosed.
According to Patent Document 3, in a carrier having a coating film having a binder resin and particles, the intrinsic resistance of the particles is 10 ¹² Ω · cm or more, and the particle size D and the binder resin film thickness h are 1 <D / h. An electrophotographic carrier of <5 is disclosed.

JP-A-2018-066892 Japanese Unexamined Patent Publication No. 2013-0615111 Japanese Unexamined Patent Publication No. 2001-188388

The present disclosure is a carrier for electrostatic charge image development having 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 less than 5 nm or more than 90 nm. Carrier, carrier for electrostatic charge image development in which the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm, or the ratio B / A of the plane view area A to the surface area B when the surface is three-dimensionally analyzed. It is an object of the present invention to provide a carrier for static charge image development that suppresses the wiping out of toner as compared with a carrier for static charge image development that is less than 1.020 or more than 1.100.

Means for solving the above problems include the following aspects.

<1> 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. A carrier for static charge image development, which is 6 μm or more and 1.4 μm or less, and the ratio B / A of the plane view area A to the surface area B is 1.020 or more and 1.100 or less when the surface is three-dimensionally analyzed.
<2> The carrier for developing an electrostatic charge image according to <1>, wherein the ratio B / A is 1.040 or more and 1.080 or less.
<3> The carrier for developing an electrostatic charge image according to <1> or <2>, wherein the average particle size of the inorganic particles is 5 nm or more and 70 nm or less.
<4> The carrier for developing an electrostatic charge image according to any one of <1> to <3>, wherein the average thickness of the resin layer is 0.8 μm or more and 1.2 μm or less.
<5> Of <1> to <4>, the inorganic particles are silica particles, and the silicon element concentration on the surface of the carrier for static charge image development determined by X-ray photoelectron spectroscopy is more than 2 atomic% and less than 20 atomic%. The carrier for developing an electrostatic charge image according to any one of the items.
<6> The carrier for developing an electrostatic charge image according to <5>, wherein the silicon element concentration is more than 5 atomic% and less than 20 atomic%.
<7> An electrostatic charge image developing agent containing the carrier for developing an electrostatic charge image according to any one of <1> to <6> and a toner for developing an electrostatic charge image.
<8> An image provided with a developing means that accommodates the static charge image developer according to <7> and develops the static charge image formed on the surface of the image holder as a toner image by the static charge image developer. A process cartridge that is attached to and detached from the forming device.
<9> 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
A developing means for accommodating the electrostatic charge image developer according to <7> and developing the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic image developer.
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.
<10> 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 developer according to <7>.
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>, the average particle size of the inorganic particles is less than 5 nm or more than 90 nm, the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm, or the surface is 3 Provided is a carrier for static charge image development that suppresses the wiping out of toner as compared with the case where the ratio B / A of the plane view area A to the surface area B is less than 1.020 or more than 1.100 when dimensionally analyzed. NS.
According to the invention according to <2>, there is provided a carrier for static charge image development that suppresses the ejection of toner as compared with the case where the ratio B / A is less than 1.040 or more than 1.080.
According to the invention according to <3>, there is provided a carrier for static charge image development that suppresses the ejection of toner as compared with the case where the average particle size of the inorganic particles is less than 5 nm or more than 70 nm.
According to the invention according to <4>, there is provided a carrier for static charge image development that suppresses the wiping out of toner 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.
According to the invention according to <5>, the transferability of the toner image is higher than that in the case where the inorganic particles are silica particles and the silicon element concentration on the surface of the carrier for static charge image development is 2 atomic% or less or 20 atomic% or more. A carrier for developing an electrostatic charge image that suppresses a decrease in the amount of particles is provided.
According to the invention according to <6>, the transferability of the toner image is higher than that in the case where the inorganic particles are silica particles and the silicon element concentration on the surface of the carrier for static charge image development is 5 atomic% or less or 20 atomic% or more. A carrier for developing an electrostatic charge image that suppresses a decrease in the amount of particles is provided.
According to the invention according to <7>, when the average particle size of the inorganic particles in the carrier for static charge image development is less than 5 nm or more than 90 nm, the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm. In this case, or when the surface is three-dimensionally analyzed, the static charge that suppresses the wiping out of the toner is compared with the case where the ratio B / A of the plane view area A to the surface area B is less than 1.020 or more than 1.100. An image developer is provided.
According to the invention according to <8>, when the average particle size of the inorganic particles in the carrier for static charge image development is less than 5 nm or more than 90 nm, the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm. In this case, or when the surface is three-dimensionally analyzed, the ratio B / A of the plane view area A to the surface area B is less than 1.020 or more than 1.100. Is provided.
According to the invention according to <9>, when the average particle size of the inorganic particles in the carrier for static charge image development is less than 5 nm or more than 90 nm, the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm. In this case, or when the surface is three-dimensionally analyzed, the ratio B / A of the plane view area A to the surface area B is less than 1.020 or more than 1.100. Equipment is provided.
According to the invention according to <10>, when the average particle size of the inorganic particles in the carrier for static charge image development is less than 5 nm or more than 90 nm, the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm. In this case, or when the surface is three-dimensionally analyzed, the ratio B / A of the plane view area A to the surface area B is less than 1.020 or more than 1.100. A method is provided.

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 disclosure 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 disclosure 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 disclosure, 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. .. Further, in the numerical range described in the present disclosure, 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 disclosure, 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 disclosure 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 disclosure, each component may contain a plurality of applicable substances. When referring to the amount of each component in the composition in the present disclosure, if a plurality of substances corresponding to each component are present in the composition, unless otherwise specified, the plurality of types present in the composition. It means the total amount of substances.

In the present disclosure, 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.

In the present disclosure, "(meth) acrylic" means at least one of acrylic and methacryl, and "(meth) acrylate" means at least one of acrylate and methacrylate.

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

<Carrier for static charge image development>
The carrier according to the present embodiment is a resin-coated carrier having magnetic particles and a resin layer that coats the magnetic particles and contains inorganic particles.
The carrier according to the present embodiment has an average particle size of inorganic particles contained in the resin layer of 5 nm or more and 90 nm or less, an average thickness of the resin layer of 0.6 μm or more and 1.4 μm or less, and has a three-dimensional surface. When analyzed, the ratio B / A of the plane view area A to the surface area B is 1.020 or more and 1.100 or less.

In this embodiment, carbon black is not an inorganic particle.

In the present embodiment, the average particle size of the inorganic particles contained in the resin layer 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 analyzer for image analysis. 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. 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 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.

The carrier according to the present embodiment suppresses the blowout of toner. The following is presumed as the mechanism.

If the toner is continuously agitated in the developing means, the toner may be agglomerated and the apparent toner particle size may be increased to cause charge fluctuation, and the toner may be wiped out of the developing means. This phenomenon tends to occur when an image having a relatively low image density is continuously formed on a recording medium having a relatively small area, and then an image having a relatively high image density is formed.
On the other hand, carriers in which the average particle size of the inorganic particles in the resin layer, the average thickness of the resin layer, and the ratio B / A are in the above ranges are developed for the reasons (a) to (c) below. It is presumed that toner aggregation in the means is unlikely to occur, and as a result, toner ejection is suppressed.

(A) When the average particle size of the inorganic particles in the resin layer is less than 5 nm, it is difficult to obtain the filler effect of increasing the strength of the resin layer, and the resin layer is easily peeled off when image formation is repeated. When the average particle size of the inorganic particles in the resin layer is more than 90 nm, the inorganic particles are likely to be detached from the convex portion of the resin layer, and the resin layer is likely to be peeled off when the image formation is repeated. In either case, it is presumed that the exposed area of the magnetic particles on the carrier surface increases, the mechanical stress on the toner increases, the toner external additive is buried in the toner particles, and toner aggregation occurs.
From the above viewpoint, the average particle size of the inorganic particles in the resin layer 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 8 nm or more and 50 nm or less. It is more preferable to have.
The average particle size of the inorganic particles contained in the resin layer can be controlled by the size of the inorganic particles used to form the resin layer.

(B) 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, and the mechanical stress on the toner increases. It is presumed that the toner external additive 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.
From the above viewpoint, 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. preferable.
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.

(C) When the ratio B / A is less than 1.020, the carrier surface is too flat, the contact between the carrier and the toner becomes surface contact, the mechanical stress on the toner is increased, and the toner external additive becomes the toner particles. It is presumed that it will be buried and toner aggregation will occur. When the ratio B / A is more than 1.100, the number of irregularities on the carrier surface is relatively large, or the height difference of the irregularities on the carrier surface is relatively large. It is presumed that the amount will increase, the amount of external additive transferred from the toner to the carrier will increase, and toner aggregation will occur.
From the above viewpoint, the ratio B / A is 1.020 or more and 1.100 or less, preferably 1.040 or more and 1.080 or less, and more preferably 1.040 or more and 1.070 or less. ..
The ratio B / A can be controlled by the manufacturing conditions for forming the resin layer. Details will be described later.

Since the carrier according to the present embodiment has a ratio B / A of 1.020 or more and 1.100 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. It is presumed that these irregularities are mostly covered with resin, but some of the inorganic particles are exposed. Unlike the resin, the exposed inorganic particles are not charged by contact with the toner, so that excessive charging of the carrier surface can be suppressed. Further, when the resin layer of the carrier is worn by repeating image formation, the unevenness is selectively worn and a part of the inorganic particles in the resin layer is newly exposed. It is presumed that if a part of the inorganic particles continues to be appropriately exposed on the carrier surface, the chargeability of the carrier surface decreases and the increase of toner charge is suppressed, and as a result, the transferability of the toner image is maintained well. Will be done. This phenomenon is remarkable when the image formation on the embossed paper is repeated in a low temperature and low humidity environment (for example, a temperature of 10 ° C. and a relative humidity of 15%).

The carrier according to the present embodiment contains silica particles in the resin layer from the viewpoint of suppressing deterioration of the transferability of the toner image when image formation is repeated for a long period of time, and silicon on the carrier surface obtained by X-ray photoelectron spectroscopy. The element concentration is preferably more than 2 atomic% and less than 20 atomic%.
When the silicon element concentration is more than 2 atomic%, it means that the silica particles are appropriately distributed on the surface of the resin layer, and therefore, the chargeability of the carrier surface is appropriately lowered.
When the silicon element concentration is less than 20 atomic%, it means that the amount of silica particles distributed on the surface of the resin layer is not too large, and therefore the chargeability of the carrier surface is not excessively lowered.
From the above viewpoint, the silicon element concentration is more preferably more than 5 atomic% and less than 20 atomic%, and further preferably more than 6 atomic% and less than 19 atomic%.
The silicon element concentration on the carrier surface can be controlled by the amount of silica particles used to form the resin layer, and the larger the amount of silica particles with respect to the amount of resin, the higher the silicon element concentration on the carrier surface.

Hereinafter, the configuration of the carrier according to the present embodiment will be described in detail.

[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.
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 acrylic resin having an alicyclic structure. As the polymerization component of the acrylic resin having an alicyclic structure, 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. Examples 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 acrylic resin having an alicyclic structure preferably contains cyclohexyl (meth) acrylate as a polymerization component. The content of the monomer unit derived from cyclohexyl (meth) acrylate contained in the acrylic resin having an alicyclic structure is preferably 75% by mass or more and 100% by mass or less with respect to the total mass of the acrylic resin having an alicyclic structure. It is more preferably 85% by mass or more and 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 content of the inorganic particles contained in the resin layer is preferably 10% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 55% by mass or less, and 20% by mass or more and 50% 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 10% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 55% by mass or less, and 20% by mass, based on the total mass of the resin layer.
More preferably, it is by mass% or more and 50% by mass or less.

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 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 ratio 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 more 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.

<Static charge image developer>
The developer according to this embodiment is a two-component developer containing the carrier and toner according to this embodiment. The toner contains toner particles and, if necessary, an external additive.

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.

[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 (eg, vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (eg, ethylene, propylene, butadiene, etc.) Examples thereof include homopolymers of the above-mentioned monomers, and vinyl-based resins composed of copolymers in which two or more kinds of these monomers are combined.
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 a resin means that it 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-value 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 K7121: 1987 "Method for measuring transition temperature of plastics", "Supplementary". It is obtained by "outer glass transition start temperature".

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 known production 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 a monomer with poor compatibility is present in the copolymerization reaction, the monomer with poor compatibility, the monomer, and the acid or alcohol to be polycondensed are condensed in advance, and then the main component and the weight are combined. It is good to condense.

-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 linear aliphatic polymerizable monomer is preferable to a polymerizable monomer having an aromatic ring.

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 known production method, like, for example, an amorphous polyester.

The content of the binder resin is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and further preferably 60% by mass or more and 85% by mass or less with respect to the entire toner particles.

-Colorant-
Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzine yellow, slene yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant. Carmin 6B, Dupont Oil Red, Pyrazolon Red, Resole Red, Rhodamine B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultra Marine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Pigments such as malachite green oxalate; aclysin, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine , Triphenylmethane-based, diphenylmethane-based, thiazole-based dyes;
As the colorant, one type may be used alone, or two or more types may be used in combination.

As the colorant, a surface-treated colorant may be used if necessary, or may be used in combination with a dispersant. Further, a plurality of kinds of colorants may be used in combination.

The content of the colorant is preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less with respect to the entire toner particles.

-Release agent-
Examples of the release agent include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax and candelilla wax; synthetic or mineral / petroleum waxes such as montan wax; 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 K7121: 1987 "Method for measuring transition temperature of plastics".

The content of the release agent is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less with respect to the entire toner particles.

-Other additives-
Examples of other additives include 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.
The toner particles having a core-shell structure are composed of, 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 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 volume average particle size (D50v) of the toner particles is measured using Coulter Multisizer II (manufactured by Beckman Coulter) and the electrolyte using ISOTON-II (manufactured by Beckman Coulter).
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 mass% 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 measured by a Coulter Multisizer II using an aperture with an aperture diameter of 100 μm. do. The number of particles to be sampled is 50,000. The volume-based particle size distribution is drawn from the small diameter side, and the cumulative particle size of 50% is defined as the volume average particle size D50v.

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.

-Manufacturing method of 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.). These manufacturing methods are not particularly limited, and known manufacturing methods are 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 resin particles A step of aggregating resin particles (other particles if necessary) in a dispersion (in a dispersion after mixing other particle dispersions if necessary) to form agglomerated particles (aggregated particle formation). Toner particles are manufactured through a step (step) and a step of heating the agglomerated particle dispersion liquid in which the agglomerated particles are dispersed and fusing and coalescing the agglomerated particles to form toner particles (fusing and coalescing step). do.

The details of each step will be described below.
In the following description, a method of obtaining toner particles containing a colorant and a release agent will be described, but the colorant and the 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-
Along 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.

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 resin particles, the resin particles may be dispersed in a dispersion medium by a phase inversion emulsification method. In the phase inversion emulsification method, a 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 an aqueous medium (W phase) is used. ) Is added to perform phase inversion from W / O to O / W, and the resin is dispersed in an aqueous medium in the form of particles.

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, LA-700 manufactured by Horiba Seisakusho) with respect to the divided particle size range (channel). The cumulative distribution is subtracted from the small particle size side, and the particle size that is cumulatively 50% of all particles is measured as the volume average particle size D50v. The volume average particle size of the particles in the other dispersions is measured in the same manner.

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

Similar to the resin particle dispersion, for example, a colorant particle dispersion and a release agent particle dispersion 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 resin particle dispersion liquid, the colorant particle dispersion liquid, and the release agent particle dispersion liquid are mixed.
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, pH 2 or more and 5 or less), a dispersion stabilizer is added as necessary, and then 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, and an aggregating agent is added at room temperature (for example, 25 ° C.) to adjust the pH of the mixed dispersion to acidic (for example, pH 2 or more and 5 or less). Then, if necessary, the dispersion stabilizer may be added and then heating may be performed.

Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant contained in the mixed dispersion, an inorganic metal salt, and a metal complex having a divalent value or higher. When a metal complex is used as the flocculant, the amount of the surfactant used is reduced and the charging characteristics are improved.
An additive that forms a complex or similar bond with the metal ion of the flocculant may be used together with the flocculant, if necessary. 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 inorganic metal salts such as polyaluminum chloride, polyaluminum hydroxide and calcium polysulfide. Polymer; and the like.
As the chelating agent, a water-soluble chelating agent may be used. Examples of the chelating agent include oxycarboxylic acids such as tartrate acid, citric acid and gluconic acid; aminocarboxylic acids such as iminodic acid vinegar (IDA), nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA); Be done.
The amount of the chelating agent added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less, 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 ° C. to 30 ° C. higher than the glass transition temperature of the resin particles) to fuse the agglomerated particles. -Merge 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 adhered to the surface of the agglomerated particles. The step of forming the second agglomerated particles and the second agglomerated particle dispersion liquid in which the second agglomerated particles are dispersed are heated, and the second agglomerated particles are fused and united to form a core. -Toner particles may be produced through a step of forming toner particles having a shell structure.

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 a dried toner particle. In the cleaning step, from the viewpoint of chargeability, it is preferable to sufficiently perform replacement cleaning with ion-exchanged water. In the solid-liquid separation step, suction filtration, pressure filtration and the like may be performed from the viewpoint of productivity. From the viewpoint of productivity, the drying step may be freeze-drying, air-flow drying, flow-drying, vibration-type flow-drying, or the like.

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.

-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, and melamine resin), cleaning activators (for example, metal salts of higher fatty acids typified by zinc stearate, particles of fluoropolymer). And so on.

The amount of the external additive added is 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.

<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.

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.
The image forming apparatus shown in FIG. 1 is a first electrophotographic system that outputs images of each color of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. A fourth image forming unit 10Y, 10M, 10C, 10K (image forming means) is provided. These image forming units (hereinafter, may be simply referred to as “units”) 10Y, 10M, 10C, and 10K are arranged side by side at a predetermined distance from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may be process cartridges that are attached to and detached from the image forming apparatus.

Above each unit 10Y, 10M, 10C, and 10K, an intermediate transfer belt (an example of an intermediate transfer body) 20 extends through each unit. The intermediate transfer belt 20 is provided by being wound around the drive roll 22 and the support roll 24, and travels in the direction from the first unit 10Y to the fourth unit 10K. A force is applied to the support roll 24 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 24. An intermediate transfer body cleaning device 30 is provided on the side surface of the image holder of the intermediate transfer belt 20 so as to face the drive roll 22.
Developing equipment for each unit 10Y, 10M, 10C, 10K (an example of developing means) Yellow, magenta, cyan, and black contained in toner cartridges 8Y, 8M, 8C, and 8K for each of 4Y, 4M, 4C, and 4K. Each toner is supplied.

Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration and operation, here, the first unit forming a yellow image arranged on the upstream side in the traveling direction of the intermediate transfer belt. Unit 10Y 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 a laser beam 3Y based on a color-separated image signal expose the charged surface. An exposure device (an example of a static charge image forming means) for forming an electrostatic charge image (an example of a static charge image forming means) 3, a developing device (an example of a developing means) for developing a static charge image by supplying a charged toner to the static charge image, and developing the image. A primary transfer roll 5Y (an example of a primary transfer means) that transfers a toner image onto an intermediate transfer belt 20, and a photoconductor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer. Are arranged in order.
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, and 5K 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 the laser beam 3Y from the exposure apparatus 3 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. The laser beam 3Y reduces the specific resistance of the irradiated portion of the photosensitizer layer, and the charged charge on the surface of the photoconductor 1Y flows. On the other hand, it is a so-called negative latent image formed by the residual charge of the portion not irradiated with the laser beam 3Y.
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. NS. 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 that 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, and 5K 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 by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed and multiple-transferred. Will be done.

The intermediate transfer belt 20 in which four color toner images are multiplex-transferred through the first to fourth units includes an intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and an image holding surface of the intermediate transfer belt 20. 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 supported by the support 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, it is preferable that the surface of the recording paper P is also smooth. 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 used. Suitable for use.

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 Liquid (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%.

[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%.

[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%, and this was used as the release agent particle dispersion (W1).

[Preparation of colorant particle dispersion liquid (K1)]
-Carbon black (manufactured by Cabot, Regal330): 50 parts-Anionic surfactant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts-Ion-exchanged water: 195 parts Dispersion treatment was carried out for 60 minutes using an impact disperser (Ultimizer HJP30006, Sugino Machine Limited) to obtain a colorant particle dispersion liquid (K1) having a solid content of 20%.

[Preparation of colorant particle dispersion liquid (C1)]
・ Cyan pigment (Pigment Blue 15: 3, Dainichiseika Kogyo): 50 parts ・ Anionic surfactant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts ・ Ion-exchanged water: 195 parts Was mixed and dispersed for 60 minutes using a high-pressure impact disperser (Ultimizer HJP30006, Sugino Machine Limited) to obtain a colorant particle dispersion (C1) having a solid content of 20%.

[Preparation of colorant particle dispersion liquid (M1)]
-Magenta pigment (Pigment Red 122, DIC): 50 parts-Anionic surfactant (Neogen RK, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 5 parts-Ion-exchanged water: 195 parts Mix the above materials and mix. Dispersion treatment was carried out for 60 minutes using a high-pressure impact disperser (Ultimizer HJP30006, Sugino Machine Limited) to obtain a colorant particle dispersion liquid (M1) having a solid content of 20%.

[Preparation of black toner particles (K1)]
-Ion-exchanged water: 200 parts-Amorphous polyester resin dispersion liquid (A1): 150 parts-Crystalographic polyester resin dispersion liquid (C1): 10 parts-Release agent particle dispersion liquid (W1): 10 parts-Coloring agent Particle dispersion (K1): 15 parts, anionic surfactant (TaycaPower): 2.8 parts Put the above material in a round stainless steel flask and add 0.1N nitrate to bring the pH to 3.5. After the adjustment, an aqueous solution of polyaluminum chloride in which 2 parts of polyaluminum chloride (manufactured by Oji Paper Co., Ltd., 30% powder product) was 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 black toner particles (K1) having a volume average particle size of 5.7 μm and an average circularity of 0.971.

[Preparation of cyan toner particles (C1)]
Similar to the production of the black toner particles (K1), however, the colorant particle dispersion liquid (K1) was changed to the colorant particle dispersion liquid (C1) to obtain cyan toner particles (C1).

[Preparation of magenta toner particles (M1)]
In the same manner as in the production of the black toner particles (K1), however, the colorant particle dispersion liquid (K1) was changed to the colorant particle dispersion liquid (M1) to obtain magenta toner particles (M1).

[Preparation of black toner (K1)]
100 parts by mass of black toner particles (K1) 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 black toner (K1) 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 cyan toner (C1)]
Similar to the production of the black toner (K1), however, the black toner particles (K1) were changed to the cyan toner particles (C1) to obtain the cyan toner (C1).

[Making Magenta Toner (M1)]
Similar to the production of the black toner (K1), however, the black toner particles (K1) were changed to magenta toner particles (M1) to obtain magenta toner (M1).

<Preparation of ferrite particles>
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.

<Preparation of silica particles to be added to the carrier resin layer>
[Silica particles (1)]
Commercially available hydrophilic silica particles (fumed silica particles, no surface treatment, volume average particle diameter of 40 nm) were prepared and used as silica particles (1).

[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 140 parts of 7.6% ammonia water were simultaneously added dropwise over 450 minutes with stirring to obtain a silica particle dispersion (A). The silica particles in the silica particle dispersion (A) have a volume average particle size of 4 nm and a volume particle size distribution index (particle size D16v having a cumulative 16% from the small diameter side and a particle size D84v having a 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 volume average particle diameter of 4 nm.

[Silica particles (3)]
Similar to the preparation of the silica particles (2), however, the amount of tetramethoxysilane and 7.6% ammonia water added during the preparation of the silica particle dispersion (A) is increased to increase the amount of the silica particles in the silica particle dispersion. The volume average particle size of the above was changed to 6 nm, and silica particles (3) surface-treated with hexamethyldisilazane were obtained. The silica particles (3) had a volume average particle diameter of 7 nm.

[Silica particles (4)]
Commercially available hydrophobic silica particles (fumed silica particles surface-treated with hexamethyldisilazane, volume average particle diameter 12 nm) were prepared and used as silica particles (4).

[Silica particles (5)]
Commercially available hydrophilic silica particles (fumed silica particles, no surface treatment, volume average particle size 62 nm) were prepared and used as silica particles (5).

[Silica particles (6)]
Commercially available hydrophobic silica particles (fumed silica particles surface-treated with hexamethyldisilazane, volume average particle size 88 nm) were prepared and used as silica particles (6).

[Silica particles (7)]
Commercially available hydrophobic silica particles (fumed silica particles surface-treated with hexamethyldisilazane, volume average particle size 93 nm) were prepared and used as silica particles (7).

<Preparation of coating agent for forming carrier resin layer>
[Coating agent (1)]
-Perfluoropropyl ethyl methacrylate-methyl methacrylate copolymer (mass-based polymerization ratio 30:70, weight average molecular weight 19000): 7.5 parts-Cyclohexyl methacrylate resin (weight average molecular weight 50,000): 9 parts-Carbon black ( Cabot, VXC72): 0.5 parts, silica particles (1): 20 parts, toluene: 250 parts, isopropyl alcohol: 50 parts Put the above materials and glass beads (diameter 1 mm, same amount as toluene) into a sand mill. Then, the mixture was stirred at a rotation speed of 190 rpm for 30 minutes to obtain a coating agent (1) having a solid content of 11%.

[Coating agents (2) to (7)]
Similar to the preparation of the coating agent (1), however, the silica particles (1) were changed to any of the silica particles (2) to (7) to obtain the coating agents (2) to (7), respectively. ..

[Coating agents (8) to (11)]
In the same manner as in the preparation of the coating agent (1), however, the addition amount of the silica particles (1) was changed as follows to obtain the coating agents (8) to (11), respectively.
-Coating agent (8): 10 parts of silica particles (1) -Coating agent (9): 12 parts of silica particles (1) -Coating agent (10): 30 parts of silica particles (1) -Coating agent (11) ): 40 parts of silica particles (1)

[Coating agent (12-1) and coating agent (12-2)]
-Coating agent (12-1)-
-Cyclohexyl methacrylate resin (weight average molecular weight 50,000): 20 parts-Polyisocyanate (Tosoh Corporation, Coronate L): 4 parts-Carbon black (Cabot, VXC72): 1 part-Toluene: 425 parts-Methanol: 50 parts The above material and glass beads (diameter 1 mm, the same amount as toluene) were put into a sand mill and stirred at a rotation speed of 1200 rpm for 30 minutes to obtain a coating agent (12-1) having a solid content of 5%.

-Coating agent (12-2)-
-Silica particles (4): 8 parts-Toluene: 92 parts The above materials and glass beads (diameter 1 mm, same amount as toluene) were put into a sand mill and stirred at a rotation speed of 1200 rpm for 30 minutes to have a solid content of 8%. A coating agent (12-2) was obtained.

<Manufacturing of resin-coated carrier>
[Career (1)]
1000 parts of ferrite particles (1) and 125 parts of coating agent (1) were put into a kneader and mixed at room temperature (25 ° C.) for 20 minutes. Then, it was heated to 70 ° C. and reduced in pressure to dry.
The dried product was cooled to room temperature (25 ° C.), 125 parts of the coating agent (1) was additionally added, and the mixture was mixed at room temperature (25 ° C.) for 20 minutes. Then, it was heated to 70 ° C. and reduced in pressure to dry.
Next, the dried product was taken out from the kneader, and the coarse powder was sieved with a mesh having a mesh size of 75 μm to obtain a carrier (1).

[Carriers (2)-(7)]
Carriers (2) to (7) were obtained in the same manner as in the preparation of the carrier (1), except that the mixing time after the additional coating agent (1) was added was changed as shown in Table 1.

[Carriers (8)-(13)]
In the same manner as in the preparation of the carrier (1), however, the coating agent (1) was changed to any of the coating agents (2) to (7) to obtain carriers (8) to (13), respectively.

[Carriers (14)-(19)]
Carriers (14) to (19) were obtained in the same manner as in the preparation of the carrier (1), except that the amount of the coating agent (1) additionally added was changed as shown in Table 1.

[Careers (20)-(23)]
In the same manner as in the preparation of the carrier (1), however, the coating agent (1) was changed to any of the coating agents (8) to (11) to obtain carriers (20) to (23), respectively.

[Carrier (24)]
Put 100 parts of ferrite particles (1) in a vacuum degassing type kneader, put 40 parts of coating agent (12-1), raise and lower the pressure while stirring, and stir for 30 minutes in an atmosphere of 90 ° C./-720 mHg. And dried. Ten parts of the coating agent (12-2) was applied to the removed carriers by a spray method, dried, and then left in an electric furnace at 150 ° C. for 1 hour for firing. The coarse powder on the sieve was removed with a mesh having a mesh size of 75 μm to obtain a carrier (24).

<Preparation of developer>
One of the carriers (1) to (24) and the black toner (K1) are placed in a V blender at a mixing ratio of carrier: toner = 100:10 (mass ratio) and stirred for 20 minutes, and the black developer (K1) is stirred. )-(K24) were obtained respectively.
In the same manner as above, however, the black toner (K1) was changed to the cyan toner (C1) to obtain cyan-colored developing agents (C1) to (C24), respectively.
In the same manner as above, however, the black toner (K1) was changed to magenta toner (M1) to obtain magenta color developers (M1) to (M24), respectively.
Hereinafter, the developer (K1), the developer (C1), and the developer (M1) are collectively referred to as a developer (1). The same applies to the developing agents (2) to (24).

<Measurement of average particle size of silica particles in the resin layer>
The carrier was embedded in epoxy resin and cut with a microtome to prepare a carrier cross section. An SEM image obtained by photographing a carrier cross section with a scanning transmission electron microscope (S-4100, manufactured by Hitachi, Ltd.) was taken into an image processing analyzer (Nireco Co., Ltd., Luzex AP) for image analysis. 100 silica particles (primary particles) in the resin layer were randomly selected, the equivalent circle diameter (nm) of each was determined, and arithmetically averaged, and this was taken as the average particle size (nm) of the silica particles.

<Measurement of average thickness of resin layer>
The above SEM image was taken into an image processing analysis apparatus (Nireco Corporation, Luzex AP) and image analysis was performed. The thickness (μm) of the resin layer was measured by randomly selecting 10 points per particle of the carrier, and then 100 carriers were measured and all were arithmetically averaged, which was taken as the average thickness (μm) of the resin layer. ..

<Surface analysis of carriers>
As an apparatus for three-dimensionally analyzing the surface of the carrier, an electron beam three-dimensional roughness analyzer ERA-8900FE manufactured by Elionix Inc. was used. The surface analysis of the carrier by ERA-8900FE was specifically performed as follows.
The surface of one carrier particle was magnified 5000 times, and three-dimensional measurement was performed by taking 400 measurement points in the long side direction and 300 points in the short side direction to obtain three-dimensional image data in a region of 24 μm × 18 μm. For 3D image data, the limit wavelength of the spline filter is set to 12 μm to remove wavelengths with a period of 12 μm or more, and the cutoff value of the Gaussian high-pass filter is set to 2.0 μm to have a period of 2.0 μm or more. The wavelength was removed and three-dimensional roughness curve data was obtained. From the three-dimensional roughness curve data, determine 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), it was determined the ratio B / A. The ratio B / A was calculated for each of the 100 carriers and arithmetically averaged.

<Measurement of silicon element concentration>
Using the carrier as a sample, analysis was performed by X-ray Photoelectron Spectroscopy (XPS) under the following conditions, and the silicon element concentration (atomic%) was determined from the peak intensity of each element.
-XPS device: VersaProbeII manufactured by ULVAC-PHI
・ Etching gun: Argon gun ・ Acceleration voltage: 5kV
・ Emission current: 20mA
・ Spatter area: 2 mm x 2 mm
・ Sputter rate: 3 nm / min (SiO ₂ conversion)

<Evaluation of toner blowout>
A modified machine of the image forming apparatus DocuPrintColor3540 (manufactured by Fuji Xerox Co., Ltd.) was prepared, and any of the developing agents (1) to (24) was put in the developing machine. The image forming apparatus was left in an environment having a temperature of 22.5 ° C. and a relative humidity of 50% for 24 hours. Under an environment of temperature 22.5 ° C. and relative humidity 50%, 100,000 black test charts with an image density of 1% are continuously output on A6 size plain paper, and then 100,000 image densities are output on A6 size plain paper. 100,000% black test charts were output continuously. After image formation, the inside of the image forming apparatus was visually observed and classified as follows.
A: No toner contamination of the cabin is observed.
B: It is recognized that the in-flight contamination by toner is very thin in a small area.
C: Slight contamination of the cabin with toner is observed, but it is within the permissible range in actual use.
D: In-flight contamination due to toner is clearly observed, which poses a problem in actual use.

<Evaluation of transferability>
An image forming apparatus DocuPrintColor400 (manufactured by Fuji Xerox Co., Ltd.) was prepared, and any of the developing agents (1) to (24) was put in the developing machine. The image forming apparatus was left in an environment having a temperature of 10 ° C. and a relative humidity of 15% for 24 hours. A test chart with an image density of 1% (blue with a cyan concentration of 50% and a magenta concentration of 50%) on A4 size embossed paper (Tokushu Tokai Paper Co., Ltd., Rezac 66) in an environment with a temperature of 10 ° C and a relative humidity of 15%. Was output continuously for 50,000 sheets. At the time of image formation, the fixing temperature was 190 ° C. and the fixing pressure was 4.0 kg / cm ² .

-Toner splattering-
The backgrounds of the 10th and 50,000th sheets were observed using a loupe with a scale of 100 times, and classified as follows.
G0: No toner splatters.
G1: Although the toner is scattered, there is no problem in actual use.
G2: Toner may scatter, which may cause a problem in actual use.
G3: Toner is scattered, which causes a problem in actual use.

-Color difference-
Using a spectrocolorimeter (X-Rite Ci62, manufactured by X-Rite), the L ^* , a ^*, and b ^* values at three locations were measured on the 10th and 50,000th images, respectively. The color difference ΔE was calculated based on the following formula, and the color difference ΔE was classified as follows.

式中、Ｌ_１、ａ_１及びｂ_１は、１０枚目の画像のＬ^＊値、ａ^＊値及びｂ^＊値（それぞれ３カ所の平均値）であり、Ｌ_２、ａ_２及びｂ_２は、５万枚目の画像のＬ^＊値、ａ^＊値及びｂ^＊値（それぞれ３カ所の平均値）である。

In the formula, L ₁ , a ₁ and b ₁ are the L ^* value, a ^* value and b ^* value (average values of each of the three locations) of _{the 10th image, and L 2} , a ₂ and b ₂ are. These are the L ^* value, a ^* value, and b ^* value (average values of each of the three locations) of the 50,000th image.

G0: Color difference ΔE is 1 or less.
G1: Color difference ΔE is more than 1 and less than 3.
G2: Color difference ΔE is more than 3 and 5 or less.
G3: Color difference ΔE is more than 5.

1Y, 1M, 1C, 1K photoconductor (example of image holder)
2Y, 2M, 2C, 2K charging roll (an example of charging means)
3 Exposure device (an example of electrostatic charge image forming means)
3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing device (example of developing means)
5Y, 5M, 5C, 5K primary transfer roll (example of primary transfer means)
6Y, 6M, 6C, 6K Photoreceptor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K Toner Cartridge 10Y, 10M, 10C, 10K Image Forming Unit 20 Intermediate Transfer Belt (Example of Intermediate Transfer)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
28 Fixing device (an example of fixing means)
30 Intermediate transfer cleaning device 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 (10)

With magnetic particles
It has 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.
The average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less.
When the surface is three-dimensionally analyzed, the ratio B / A of the plane view area A to the surface area B is 1.020 or more and 1.100 or less.
Carrier for static charge image development. The carrier for developing an electrostatic charge image according to claim 1, wherein the ratio B / A is 1.040 or more and 1.080 or less. The carrier for developing an electrostatic charge image according to claim 1 or 2, wherein the average particle size of the inorganic particles is 5 nm or more and 70 nm or less. The carrier for developing an electrostatic charge image according to any one of claims 1 to 3, wherein the average thickness of the resin layer is 0.8 μm or more and 1.2 μm or less. The inorganic particles are silica particles,
The static charge image development according to any one of claims 1 to 4, wherein the silicon element concentration on the surface of the carrier for electrostatic charge image development determined by X-ray photoelectron spectroscopy is more than 2 atomic% and less than 20 atomic%. Carrier. The carrier for developing an electrostatic charge image according to claim 5, wherein the silicon element concentration is more than 5 atomic% and less than 20 atomic%. An electrostatic charge image developing agent comprising the carrier for developing an electrostatic charge image according to any one of claims 1 to 6 and a toner for developing an electrostatic charge image. A developing means for accommodating the electrostatic charge image developing agent according to claim 7 and developing the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic charge image developing agent is provided.
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
A developing means for accommodating the electrostatic charge image developer according to claim 7 and developing the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic image developer.
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 claim 7.
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.

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