JP7415666B2 - Electrostatic image developer, process cartridge, image forming device, and image forming method - Google Patents

Description

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

Patent Document 1 discloses a carrier body having a core material and a coating resin layer covering the core material, a volume average particle size of 50 nm or more and 300 nm or less, and 0.001 parts by mass based on 100 parts by mass of the carrier body. A carrier for developing an electrostatic image is disclosed, which includes spherical silica particles attached to the surface of the carrier main body in a proportion of 0.100 parts by mass or less.

Japanese Patent Application Publication No. 2011-186005

Toner particles containing a crystalline resin have a soft surface and external additives are likely to be buried therein, so that the fluidity of the toner is likely to decrease due to the external additives being buried. Therefore, when forming an image (for example, forming a halftone image) especially under a high temperature and high humidity environment (for example, at a temperature of 28.5°C and a humidity of 85%), uneven gloss caused by toner aggregates may occur. This may occur in images.

In the present invention, the toner particles contain a crystalline resin, the average particle diameter of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, the average thickness of the resin layer is less than 0.6 μm or more than 1.4 μm, or the ratio B/ It is an object of the present invention to provide an electrostatic image developer in which uneven gloss of images is suppressed compared to when A is less than 1.020 or more than 1.100.

Means for solving the above problems include the following aspects.

<1> A toner having toner particles containing a crystalline resin and an external additive attached to the surface of the toner particles;
It has magnetic particles and a resin layer covering the magnetic particles and containing inorganic particles, wherein the average particle size of the inorganic particles is 5 nm or more and 90 nm or less, and the average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less. A carrier whose surface is three-dimensionally analyzed and has a ratio B/A of area A in plan view to surface area B of 1.020 or more and 1.100 or less,
An electrostatic image developer having:

<2> The electrostatic image developer according to <1>, wherein the ratio B/A is 1.040 or more and 1.080 or less.
<3> The electrostatic image developer according to <2>, wherein the ratio B/A is 1.050 or more and 1.080 or less.
<4> The electrostatic image developer according to any one of <1> to <3>, wherein the inorganic particles have an average particle size of 5 nm or more and 70 nm or less.
<5> The electrostatic image developer according to <4>, wherein the inorganic particles have an average particle size of 5 nm or more and 50 nm or less.
<6> The electrostatic image developer according to any one of <1> to <5>, wherein the average thickness of the resin layer is 0.8 μm or more and 1.2 μm or less.
<7> The electrostatic image developer according to any one of <1> to <6>, wherein the inorganic particles are silica particles.

<8> The electrostatic image developer according to any one of <1> to <7>, wherein the crystalline resin has a melting point of 65° C. or higher and 90° C. or lower.
<9> The electrostatic image developer according to any one of <1> to <8>, wherein the content of the crystalline resin is 5% by mass or more and 30% by mass or less based on the entire toner particles.
<10> The electrostatic image developer according to any one of <1> to <9>, wherein the toner has a flow tester 1/2 drop temperature of 90° C. or more and 140° C. or less.

<11> The electrostatic image development according to any one of <1> to <10>, wherein the average particle size of the inorganic particles is 0.015 times or more and 10 times or less of the average particle size of the external additive. agent.

<12> Contains the electrostatic image developer according to any one of <1> to <11>, and converts an electrostatic image formed on the surface of an image carrier into a toner image by the electrostatic image developer. It is equipped with a developing means for developing as
A process cartridge that can be attached to and removed from an image forming apparatus.
<13> Image carrier;
Charging means for charging the surface of the image carrier;
an electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
The electrostatic charge image developer according to any one of <1> to <11> is contained, and the electrostatic charge image formed on the surface of the image carrier is developed as a toner image by the electrostatic charge image developer. a developing means for
a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
a fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising:
<14> A charging step of charging the surface of the image carrier;
an electrostatic charge image forming step of forming an electrostatic charge image on the surface of the charged image carrier;
A developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to any one of <1> to <11>;
a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
a fixing step of fixing the toner image transferred to the surface of the recording medium;
An image forming method comprising:

According to the invention according to <1> or <7>, the toner particles contain a crystalline resin, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, and the average thickness of the resin layer is less than 0.6 μm. or more than 1.4 μm, or the ratio B/A is less than 1.020 or more than 1.100, an electrostatic image developer is provided in which uneven gloss of images is suppressed.

According to the invention according to <2>, an electrostatic image developer is provided in which uneven gloss of images is suppressed compared to cases where the ratio B/A is less than 1.040 or more than 1.080.
According to the invention according to <3>, an electrostatic image developer is provided in which uneven gloss of images is suppressed compared to cases where the ratio B/A is less than 1.050 or more than 1.080.
According to the invention according to <4>, an electrostatic image developer is provided in which uneven gloss of images is suppressed compared to a case where the average particle size of inorganic particles contained in the resin layer of the carrier is more than 70 nm.
According to the invention according to <5>, an electrostatic image developer is provided in which uneven gloss of an image is suppressed compared to a case where the average particle size of inorganic particles contained in the resin layer of the carrier is more than 50 nm.
According to the invention according to <6>, an electrostatic image developer is provided in which uneven gloss of images is suppressed compared to cases 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 <8>, even if the melting point of the crystalline resin is 65°C or more and 90°C or less, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, and the average thickness of the resin layer An electrostatic image developer is provided in which uneven gloss of images is suppressed compared to cases where the particle size is less than 0.6 μm or more than 1.4 μm, or the ratio B/A is less than 1.020 or more than 1.100.
According to the invention according to <9>, even if the content of the crystalline resin is 5% by mass or more and 30% by mass or less, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, and the resin layer Provided is an electrostatic image developer in which uneven gloss of images is suppressed compared to cases where the average thickness is less than 0.6 μm or more than 1.4 μm, or the ratio B/A is less than 1.020 or more than 1.100. Ru.
According to the invention according to <10>, even if the 1/2 drop temperature of the flow tester in the toner is 90°C or more and 140°C or less, the average particle size of the inorganic particles contained in the resin layer of the carrier exceeds 90 nm, and the resin An electrostatic image developer in which uneven gloss of images is suppressed compared to cases where the average layer thickness is less than 0.6 μm or more than 1.4 μm, or the ratio B/A is less than 1.020 or more than 1.100. provided.

According to the invention according to <11>, an electrostatic image developer is provided in which uneven gloss of images is suppressed compared to a case where the average particle size of the inorganic particles is more than 10 times the average particle size of the external additive. Ru.

According to the invention according to <12>, the toner particles contain a crystalline resin, the average particle diameter of the inorganic particles contained in the resin layer of the carrier is more than 90 nm, and the average thickness of the resin layer is less than 0.6 μm or 1.4 μm. Provided is a process cartridge in which uneven gloss of an image is suppressed compared to when an electrostatic image developer having a ratio B/A of 1.020 or 1.020 or greater than 1.100 is used.
According to the invention according to <14>, the toner particles contain a crystalline resin, the average particle diameter of the inorganic particles contained in the resin layer of the carrier is more than 90 nm, and the average thickness of the resin layer is less than 0.6 μm or 1.4 μm. Provided is an image forming apparatus in which uneven gloss of an image is suppressed compared to when an electrostatic image developer having a B/A ratio of 1.020 or 1.020 or greater than 1.100 is used.
According to the invention according to <15>, the toner particles contain a crystalline resin, the average particle diameter of the inorganic particles contained in the resin layer of the carrier is more than 90 nm, and the average thickness of the resin layer is less than 0.6 μm or 1.4 μm. Provided is an image forming method in which uneven gloss of an image is suppressed compared to when an electrostatic image developer having a B/A ratio of 1.020 or 1.020 or greater than 1.100 is used.

1 is a schematic configuration diagram showing an example of an image forming apparatus according to an embodiment. FIG. 2 is a schematic configuration diagram showing an example of a process cartridge that is attached to and detached from the image forming apparatus according to the present embodiment.

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

In this specification, a numerical range indicated using "~" indicates a range that includes the numerical values written before and after "~" as the minimum and maximum values, respectively.

In the numerical ranges described step by step in this specification, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value of another numerical range described step by step. good. Further, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with the value shown in the Examples.

In this specification, the term "process" is used not only to refer to an independent process, but also to include any process that is not clearly distinguishable from other processes as long as the intended purpose of the process is achieved. .

When embodiments are described in this specification with reference to drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the members in each figure are conceptual, and the relative size relationships between the members are not limited thereto.

In this specification, each component may contain multiple types of corresponding substances. In this specification, when referring to the amount of each component in a composition, if there are multiple types of substances corresponding to each component in the composition, unless otherwise specified, the multiple types present in the composition means the total amount of substances.

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

In this specification, "(meth)acrylic" means at least one of acrylic and methacrylic, and "(meth)acrylate" means at least one of acrylate and methacrylate.

[Electrostatic image developer]
The electrostatic image developer (hereinafter also referred to as "developer") according to the present embodiment includes a toner having toner particles containing a crystalline resin and an external additive attached to the surface of the toner particles, and a toner having magnetic particles and the external additive attached to the surface of the toner particle. a resin layer covering magnetic particles and containing 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, and the surface The carrier has a ratio B/A of area A to surface area B in plan view of 1.020 or more and 1.100 or less when analyzed three-dimensionally.

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

In this embodiment, the average particle diameter of inorganic particles contained in the resin layer in the carrier and the average thickness of the resin layer are determined by the following method.
The carrier is embedded in epoxy resin and cut with a microtome to create a cross section of the carrier. An SEM image of a cross section of the carrier taken using a scanning electron microscope (SEM) is taken into an image processing and analysis device to perform image analysis. 100 inorganic particles (primary particles) in the resin layer are selected at random, the equivalent circle diameter (nm) of each is determined, and the arithmetic average is taken as the average particle diameter (nm) of the inorganic particles. That is, the average particle size of the inorganic particles is the number average particle size.
In addition, the thickness (μm) of the resin layer was measured by randomly selecting 10 locations per carrier particle, and further measurements were taken for 100 carriers, all of which were arithmetic averaged, and this was calculated as the average thickness (μm) of the resin layer. shall be.

In this embodiment, the ratio B/A in the carrier is an index for evaluating surface roughness. The ratio B/A is determined by the following method, for example.
As a device for three-dimensionally analyzing the surface of the carrier, a scanning electron microscope with four secondary electron detectors (e.g., electron beam three-dimensional roughness analyzer ERA-8900FE manufactured by Elionix Co., Ltd.) was used, and the analysis was performed as follows. I do.
The surface of carrier 1 particle is magnified 5000 times. The interval between measurement points is 0.06 μm, 400 measurement points are taken in the long side direction, and 300 measurement points are taken in the short side direction, and an area of 24 μm×18 μm is measured to obtain three-dimensional image data.
For three-dimensional image data, the limit wavelength of a spline filter (frequency selection filter using a spline function) is set to 12 μm to remove wavelengths with a period of 12 μm or more, thereby removing waviness components on the carrier surface and reducing roughness. Extract the components and obtain the roughness curve.
Furthermore, the cutoff value of the Gaussian high-pass filter (frequency selection filter using a Gaussian function) is set to 2.0 μm to remove wavelengths with a period of 2.0 μm or more, and thereby, from the roughness curve after spline filter processing, Wavelengths corresponding to the convex portions of the magnetic particles exposed on the carrier surface are removed to obtain a roughness curve in which wavelength components with a period of 2.0 μm or more are removed.
From the three-dimensional roughness curve data after filter processing, the surface area B (μm ² ) of a region of 12 μm×12 μm at the center (planar view area A=144 μm ² ) is determined, and the ratio B/A is determined. The ratio B/A is obtained for each of the 100 carriers and arithmetic averaged.

According to the developer of this embodiment, uneven gloss in an image is suppressed. Although the reason is not certain, it is assumed as follows.

Toner particles containing a crystalline resin have a softer surface than toner particles not containing a crystalline resin, and in particular, toner particles containing a crystalline resin and an amorphous resin that are easily compatible with each other, The surface of toner particles tends to become soft due to the compatibility of the resins. Therefore, when low-density images are continuously formed, the toner in the developing means is stirred together with the carrier for a long period of time with little replacement, so that the external additive is likely to be buried in the surface of the toner particles.
When the external additive is embedded in the surface of the toner particles, it is difficult to obtain the effect of improving the fluidity of the toner by the external additive, and the fluidity of the toner decreases due to the increased opportunity for toner particles to come into contact with each other, resulting in the formation of toner aggregates. may be formed. In particular, in a high temperature, high humidity environment (eg, a temperature of 28.5° C. and a humidity of 85%), toner aggregates are likely to be formed. Therefore, when forming an image (for example, forming a halftone image on a thin recording medium), uneven gloss may occur in the image due to the toner aggregates due to the heat during image fixation.

In contrast, in the present embodiment, the carrier has a resin layer containing inorganic particles having an average particle size of 5 nm or more and 90 nm or less, and the average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less, and The ratio B/A is 1.020 or more and 1.100 or less. That is, in this embodiment, fine irregularities exist on the surface of the carrier.
Therefore, due to the fine irregularities on the surface of the carrier, the contact with the toner becomes point contact, and the contact area becomes small, which is thought to alleviate the load caused by stirring and suppress the embedding of the external additive. It is assumed that by suppressing the embedding of the external additive, a decrease in the fluidity of the toner is suppressed, and uneven gloss of images caused by toner aggregates is suppressed. The toner and carrier constituting the agent will be explained in detail.

<Toner>
The toner includes toner particles containing a crystalline resin as a binder resin and an external additive attached to the surface of the toner particles.

(toner particles)
The toner particles include, for example, a binder resin, and if necessary, a colorant, a release agent, and other additives.

-Binder resin-
The binder resin includes at least a crystalline resin.
Examples of crystalline resins include, but are not limited to, crystalline polyester resins, crystalline vinyl resins (e.g., polyalkylene resins, long-chain alkyl (meth)acrylate resins, etc.), crystalline epoxy resins, crystalline polyurethane resins, Known resins include crystalline cellulose resin, crystalline polyether resin, crystalline polyamide resin, and modified rosin.
Among these, it is preferable that the binder resin contains a crystalline polyester resin as the crystalline resin.

The melting point of the crystalline resin is, for example, in the range of 65°C or more and 90°C or less, preferably in the range of 70°C or more and 85°C or less, and more preferably in the range of 70°C or more and 80°C or less.
When the melting point of the crystalline resin is 90° C. or lower, it becomes easier to obtain low-temperature fixability of the toner. On the other hand, when the melting point of the crystalline resin is low, the surface of the toner particles tends to become soft, but by including the carrier, embedding of the external additive is suppressed, and uneven gloss of the image is suppressed. In addition, since the melting point of the crystalline resin is 65°C or higher, the surface of the toner particles does not become too soft compared to the case where the melting point is lower than 65°C, and embedding of external additives is easily suppressed, which reduces uneven gloss of images. suppressed. That is, by setting the melting point of the crystalline resin to 65° C. or higher and 90° C. or lower, both low-temperature fixability and suppression of image gloss unevenness are achieved.
The melting point of the crystalline resin is determined from the DSC curve obtained by differential scanning calorimetry (DSC), and is determined by the "melting peak temperature" described in the method for determining the melting temperature of JIS K7121-1987 "Method for measuring transition temperature of plastics". Find it by

The content of the crystalline resin is preferably 5% by mass or more and 30% by mass or less, and 5% by mass or more based on the entire toner particles, from the viewpoint of achieving both low-temperature fixability of the toner and suppression of uneven gloss of the image. It is more preferably 25% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less.
Further, the content of the crystalline resin is preferably 3% by mass or more and 25% by mass or less based on the entire binder resin, from the viewpoint of achieving both the low-temperature fixability of the toner and the suppression of uneven gloss of the image. It is more preferably 3% by mass or more and 15% by mass or less, and even more preferably 3% by mass or more and 15% by mass or less.

It is preferable that the binder resin further contains an amorphous resin in addition to the crystalline resin.
Examples of amorphous resins include styrenes (for example, styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylates (for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (such as acrylonitrile) , methacrylonitrile, etc.), vinyl ethers (e.g. vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (e.g. ethylene, propylene, butadiene, etc.) Examples include vinyl resins made of homopolymers of monomers such as, or copolymers of a combination of two or more of these monomers.
Examples of the amorphous 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 and the above-mentioned vinyl resins, or Also included are graft polymers obtained by polymerizing vinyl monomers in the coexistence of.
Among these, it is preferable that the binder resin contains an amorphous polyester resin as an amorphous resin.

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

Note that the "crystallinity" of a resin refers to having a clear endothermic peak in differential scanning calorimetry (DSC) rather than a stepwise change in endothermic amount. /min) indicates that the half width of the endothermic peak is within 10°C.
On the other hand, the term "amorphous" of a resin means that the half-width exceeds 10° C., that it exhibits a stepwise change in endothermic amount, or that no clear endothermic peak is observed.

Preferably, the binder resin includes a crystalline polyester resin as the crystalline resin and an amorphous polyester resin as the amorphous resin.
Hereinafter, a crystalline polyester resin and an amorphous polyester resin will be described in detail as examples of a crystalline resin and an amorphous resin, respectively.

-Amorphous polyester resin Examples of the amorphous polyester resin include condensation polymers of polyhydric carboxylic acids and polyhydric alcohols. Note that as the amorphous polyester resin, a commercially available product or a synthesized one may be used.

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

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

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

Amorphous polyester resin can be obtained by a well-known manufacturing method. Specifically, it can be obtained, for example, by a method in which the polymerization temperature is set at 180° C. or more and 230° C. or less, the pressure inside the reaction system is reduced as necessary, and the reaction is carried out while removing water and alcohol generated during condensation.
In addition, when the raw material monomers are not dissolved or compatible at the reaction temperature, a high boiling point solvent may be added as a solubilizing agent to dissolve them. In this case, the polycondensation reaction is carried out while distilling off the solubilizing agent. If there are monomers with poor compatibility, it is best to condense the monomer with poor compatibility and the acid or alcohol to be polycondensed in advance, and then polycondense them together with the main component. .

-Crystalline polyester resin Examples of crystalline polyester resins include polycondensates of polyhydric carboxylic acids and polyhydric alcohols. Note that as the crystalline polyester resin, a commercially available product or a synthesized product may be used.
Here, the crystalline polyester resin is preferably a polycondensate using a polymerizable monomer having a linear aliphatic group rather than a polymerizable monomer having an aromatic group, since the crystalline polyester resin easily forms a crystal structure.

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

Examples of the polyhydric alcohol include aliphatic diols (for example, linear aliphatic diols in which the number of carbon atoms in the main chain portion is 7 or more and 20 or less). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18- Examples include octadecanediol and 1,14-eicosandecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as the aliphatic diol.
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.
One type of polyhydric alcohol may be used alone, or two or more types may be used in combination.

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

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

Crystalline polyester resins can be obtained, for example, by well-known manufacturing methods in the same manner as amorphous polyester resins.

When the binder resin includes a crystalline polyester resin and an amorphous polyester resin, from the viewpoint of compatibility between the crystalline resin and the amorphous resin, the carbon number of the polyhydric alcohol used as a monomer of the crystalline polyester resin is It is preferably 2 or more and 16 or less, more preferably 2 or more and 12 or less, and even more preferably 2 or more and 10 or less.

The content of the binder resin is, for example, preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and 60% by mass or more and 85% by mass or less, based on the entire toner particles. More preferred.

-Coloring agent-
Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzidine yellow, suren yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant. Carmine 6B, DuPont Oil Red, Pyrazolone Red, Lysole Red, Rhodamine B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Various pigments such as malachite green oxalate, acridine series, xanthene series, azo series, benzoquinone series, azine series, anthraquinone series, thioindico series, dioxazine series, thiazine series, azomethine series, indico series, phthalocyanine series, aniline black Examples include various types of dyes, such as polymethine, triphenylmethane, diphenylmethane, and thiazole dyes.
One type of colorant may be used alone, or two or more types may be used in combination.

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

The content of the colorant is, for example, preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 15% by mass or less, based on the entire toner particles.

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

The melting temperature of the mold release agent is preferably 50°C or more and 110°C or less, more preferably 60°C or more and 100°C or less.
The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in the method for determining the melting temperature of JIS K 7121-1987 "Method for measuring transition temperature of plastics". .

The content of the release agent is, for example, preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, based on the entire toner particles.

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

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

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

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

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

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

(external additive)
Examples of external additives include inorganic particles. The inorganic particles include SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO. Examples include SiO ₂ , K ₂ O.(TiO ₂ )n, Al _{2 O} 3.2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ and MgSO ₄ .

The surface of the inorganic particles used as the external additive is preferably subjected to a hydrophobic treatment. The hydrophobization treatment is performed, for example, by immersing the inorganic particles in a hydrophobization treatment agent. The hydrophobizing agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents, and the like. 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, based on 100 parts by mass of the inorganic particles.

Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning active agents (for example, metal salts of higher fatty acids such as zinc stearate, and fluorine-based polymers). particles), etc.

From the viewpoint of improving the fluidity of the toner, the external additive preferably contains inorganic particles, and among the inorganic particles, preferably contains silica particles.
The average particle diameter of the external additive is, for example, in the range of 5 nm or more and 300 nm or less, preferably in the range of 10 nm or more and 250 nm or less, and more preferably in the range of 10 nm or more and 200 nm or less.
The average particle size of the external additive is determined in the same manner as the average particle size of the inorganic particles contained in the resin layer of the carrier.
Specifically, a SEM image of the toner surface taken using a scanning electron microscope (SEM) is taken into an image processing and analysis device and image analysis is performed. 100 external additives (primary particles) on the surface of the toner are randomly selected, the equivalent circle diameter (nm) of each is determined, and the arithmetic average is taken as the average particle diameter (nm) of the external additive. That is, the average particle size of the external additive is the number average particle size.

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

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

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

Specifically, for example, when toner particles are manufactured by an aggregation coalescence method,
The process of preparing a resin particle dispersion in which resin particles that will become the binder resin are dispersed (resin particle dispersion preparation process), and (in a dispersion liquid), a step of agglomerating resin particles (other particles as necessary) to form agglomerated particles (agglomerated particle formation step), and heating the agglomerated particle dispersion liquid in which the agglomerated particles are dispersed. Toner particles are manufactured through a step of fusing and coalescing the aggregated particles to form toner particles (fusing and coalescing step).

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

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

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

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

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

In the resin particle dispersion, methods for dispersing resin particles in a dispersion medium include, for example, general dispersion methods such as a rotary shear type homogenizer, a ball mill with media, a sand mill, and a dyno mill. Further, depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method.
Note that the phase inversion emulsification method involves dissolving the resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, adding a base to the organic continuous phase (O phase) to neutralize it, and then dissolving it in an aqueous medium. (W phase), the resin is converted from W/O to O/W (so-called phase inversion) to form a discontinuous phase, and the resin is dispersed in the form of particles in an aqueous medium. It is.

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

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

Note that, in the same manner as the resin particle dispersion, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared. In other words, regarding the volume average particle diameter, dispersion medium, dispersion method, and content of particles in the resin particle dispersion, the colorant particles dispersed in the colorant particle dispersion and the release agent particle dispersion The same applies to the releasing agent particles to be dispersed.

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

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

Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as a dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher valence metal complex. In particular, when a metal complex is used as the flocculant, the amount of 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 as necessary. A chelating agent is preferably used as this additive.

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

-Fusion/unification process-
Next, the agglomerated particle dispersion liquid in which the agglomerated particles are dispersed is heated, for example, to a temperature higher than the glass transition temperature of the resin particles (for example, a temperature higher than the glass transition temperature of the resin particles by 10 to 30 degrees Celsius), and the agglomerated particles are heated to a temperature higher than the glass transition temperature of the resin particles. fuse and coalesce to form toner particles.

Through the above steps, toner particles are obtained.
Note that after obtaining the aggregated particle dispersion liquid in which aggregated particles are dispersed, the aggregated particle dispersion liquid and the resin particle dispersion liquid in which resin particles are dispersed are further mixed to further coat the surface of the aggregated particles with resin particles. a step of agglomerating so as to adhere to form a second agglomerated particle; heating a second agglomerated particle dispersion liquid in which the second agglomerated particles are dispersed to fuse and coalesce the second agglomerated particles; The toner particles may be manufactured through the steps of forming toner particles having a core/shell structure.

Here, after the fusion/unification 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 dried toner particles.
In the washing step, it is preferable to sufficiently perform displacement washing with ion-exchanged water from the viewpoint of chargeability. Further, the solid-liquid separation step is not particularly limited, but from the viewpoint of productivity, it is preferable to perform suction filtration, pressure filtration, or the like. Further, there is no particular restriction on the drying process, but from the viewpoint of productivity, it is preferable to perform freeze drying, flash drying, fluidized drying, vibrating fluidized drying, or the like.

The toner according to the present embodiment is manufactured, for example, by adding and mixing external additives to the obtained dry toner particles. Mixing may be carried out using, for example, a V-blender, a Henschel mixer, a Loedige mixer, or the like. Furthermore, if necessary, coarse toner particles may be removed using a vibrating sieve, a wind sieve, or the like.

(Characteristics of toner, etc.)
The 1/2 drop temperature of the flow tester of the toner is preferably 90°C or more and 140°C or less, more preferably 95°C or more and 120°C or less, and even more preferably 95°C or more and 115°C or less.
When the 1/2 drop temperature of the flow tester of the toner is 90° C. or more and 140° C. or less, it becomes easier to obtain low-temperature fixability of the toner. On the other hand, if the 1/2 drop temperature of the flow tester in the toner is 90°C or more and 140°C or less, the surface of the toner particles tends to become soft, but by including the carrier, embedding of the external additive is suppressed, and the image quality is improved. uneven gloss is suppressed.

The 1/2 drop temperature of the flow tester in toner was measured using a Koka type flow tester CFT-500C (manufactured by Shimadzu Corporation). Conditions: hole length 1 mm, pressure load 0.98 MPa (10 kg/cm ² ), preheat time 5 minutes, temperature increase rate 1°C/min, measurement temperature interval 1°C, starting temperature 65°C. Below, the temperature is set to correspond to 1/2 of the height from the start point to the end point when 1.1 g of the sample is melted and flowed out.

<Career>
The carrier is a resin-coated carrier that includes magnetic particles and a resin layer that covers the magnetic particles and includes inorganic particles.

(magnetic particles)
The magnetic particles are not particularly limited, and known magnetic particles used as core materials of carriers are applicable. Specifically, magnetic particles include particles of magnetic metals such as iron, nickel, and cobalt; particles of magnetic oxides such as ferrite and magnetite; resin-impregnated magnetic particles obtained by impregnating porous magnetic powder with resin; Examples include magnetic powder-dispersed resin particles in which magnetic powder is dispersed and blended. In this embodiment, the magnetic particles are preferably ferrite particles.

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 even more 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, 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 using a surface shape measuring device (for example, "Ultra-deep color 3D shape measuring microscope VK-9700" manufactured by Keyence Corporation) at an appropriate magnification (for example, 1000 magnification). Observe the magnetic particles at a magnification of 0.08 mm, 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. The Ra of 100 magnetic particles is arithmetic averaged.

The magnetic force of the magnetic particles is such that the saturation magnetization in a magnetic field of 3000 Oe is preferably 50 emu/g or more, more preferably 60 emu/g or more. The saturation magnetization is measured using a vibrating sample type magnetic measuring device VSMP10-15 (manufactured by Toei Kogyo Co., Ltd.). The sample to be measured is packed into a cell with an inner diameter of 7 mm and a height of 5 mm, and set in the device. Measurements are performed by applying an applied magnetic field and sweeping up to 3000 oersteds. Next, the applied magnetic field is reduced to create a hysteresis curve on the recording paper. Calculate saturation magnetization, residual magnetization, and coercive force from the curve data.

The volume electrical resistance (volume resistivity) of the magnetic particles is preferably 1 x 10 ⁵ Ω-cm or more and 1 x 10 ⁹ Ω-cm or less, more preferably 1 x 10 ⁷ Ω-cm or more and 1 x 10 ⁹ Ω-cm or less. preferable.
The volume electrical resistance (Ω·cm) of the magnetic particles is measured as follows. The object to be measured is placed flat on the surface of a circular jig equipped with a 20 cm ² electrode plate to form a layer with a thickness of 1 mm or more and 3 mm or less. The 20 cm ² electrode plate is placed on top of this to sandwich the layers. In order to eliminate gaps between the objects to be measured, the thickness (cm) of the layer is measured after applying a load of 4 kg to the electrode plate placed 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 volume electrical resistance (Ω·cm) of the object to be measured is as shown in the following formula.
Formula: R=E×20/(I−I ₀ )/L
In the above formula, R is the volume electrical resistance of the object to be measured (Ω・cm), E is the applied voltage (V), I is the current value (A), _I0 is the current value (A) at the applied voltage of 0 V, and L is the Each represents the thickness (cm) of the layer. The coefficient 20 represents the area (cm ² ) of the electrode plate.

(resin layer)
Examples of the resin constituting the resin layer include styrene/acrylic acid copolymer; polyolefin resins such as polyethylene and polypropylene; polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, Polyvinyl or polyvinylidene resins such as polyvinyl ether and polyvinyl ketone; vinyl chloride/vinyl acetate copolymers; straight silicone resins consisting of organosiloxane bonds or modified products thereof; polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, Examples include fluororesins such as polychlorotrifluoroethylene; polyesters; polyurethanes; polycarbonates; amino resins such as urea/formaldehyde resins; and epoxy resins.

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

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; and metal compound particles such as gold, silver, and copper. Examples include metal particles; and the like. Among these, silica particles are preferred from the viewpoint of suppressing toner bubbling and maintaining transferability of toner images.

The surfaces of the inorganic particles may be subjected to hydrophobic treatment. Examples of the hydrophobizing agent include known organosilicon compounds having an alkyl group (e.g., methyl group, ethyl group, propyl group, butyl group, etc.), and specific examples include alkoxysilane compounds, siloxane compounds, and silazane compounds. Examples include compounds. Among these, the hydrophobizing agent is preferably a silazane compound, and preferably hexamethyldisilazane. The hydrophobizing agents 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 supercritical carbon dioxide, and the hydrophobizing agent is applied to the surface of the inorganic particles. A method for attaching the hydrophobizing agent to the surface of the inorganic particles by applying (e.g., spraying or coating) a solution containing a hydrophobizing agent and a solvent that dissolves the hydrophobizing agent to the surface of the inorganic particles in the atmosphere. Method for adhering; After adding and holding a solution containing a hydrophobizing agent and a solvent that dissolves the hydrophobizing agent to an inorganic particle dispersion in the atmosphere, a mixed solution of the inorganic particle dispersion and the solution is added. A method of drying.

The average particle diameter of the inorganic particles is 5 nm or more and 90 nm or less, preferably 5 nm or more and 70 nm or less, more preferably 5 nm or more and 50 nm or less, and even more preferably 8 nm or more and 50 nm or less.
When the average particle size of the inorganic particles is 5 nm or more, a filler effect that increases the strength of the resin layer can be easily obtained, and peeling of the resin layer when image formation is repeated is suppressed. In addition, if the resin layer peels off, the exposed area of the magnetic particles on the carrier surface increases, the mechanical load on the toner becomes stronger, the external additive becomes more likely to be buried in the toner particles, and toner aggregation is more likely to occur. It is assumed that. Therefore, it is presumed that toner aggregation is suppressed when the average particle size of the inorganic particles is 5 nm or more.
When the average particle size of the inorganic particles is 90 nm or less, the inorganic particles are unlikely to be detached from the convex portions of the resin layer, and peeling of the resin layer during repeated image formation is suppressed. In addition, since the average particle size of the inorganic particles is 90 nm or less, the unevenness on the carrier surface becomes fine, and the contact with the toner becomes point contact, which alleviates the load caused by stirring and suppresses the embedding of external additives. Ru. Therefore, it is presumed that toner aggregation is suppressed.
The average particle size of the inorganic particles may be controlled by adjusting the size of the inorganic particles used to form the resin layer.

The average particle size of the inorganic particles is preferably 0.015 times or more and 10 times or less, and 0.02 times or more and 5 times or less, the average particle size of the external additive contained in the toner, from the viewpoint of suppressing a decrease in the fluidity of the toner. It is more preferably not more than 0.05 times and even more preferably not more than 1 time.

The content of 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 or less, based on 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 or more and 50% by mass or less, based on the total mass of the resin layer. % or less is more preferable.

The resin layer may contain conductive particles for the purpose of controlling charging and resistance. Examples of the conductive particles include carbon black and particles having conductivity among the aforementioned inorganic particles.

Examples of methods 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 that uses a solvent to dissolve or disperse the resin constituting the resin layer. On the other hand, the dry manufacturing method is a manufacturing method that does not use the above-mentioned solvent.

Wet manufacturing methods include, for example, a dipping method in which magnetic particles are immersed in a resin solution for forming a resin layer and coated; a spray method in which a resin solution for forming a resin layer is sprayed onto the surface of the magnetic particles; and a method in which magnetic particles are fluidized in a fluidized bed. Examples include a fluidized bed method in which a resin liquid for forming a resin layer is sprayed in a state where the magnetic particles are mixed with a resin liquid for forming a resin layer; a kneader coater method in which magnetic particles and a resin liquid for forming a resin layer are mixed in a kneader coater and the solvent is removed; These manufacturing methods may be repeated or combined.
The resin liquid for forming a resin layer used in the wet manufacturing 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.

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

The average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less, preferably 0.8 μm or more and 1.2 μm or less, and more preferably 0.8 μm or more and 1.1 μm or less.
When the average thickness of the resin layer is 0.6 μm or more, peeling of the resin layer when image formation is repeated is suppressed. It is assumed that when the resin layer peels off, the exposed area of the magnetic particles on the carrier surface increases, the mechanical load on the toner increases, the external additive becomes more likely to be buried in the toner particles, and toner aggregation is more likely to occur. be done. Further, when the average thickness of the resin layer is 0.6 μm or more, the dispersibility of the inorganic particles in the resin layer becomes high, and the unevenness on the surface of the carrier tends to be almost uniform.
By having an average thickness of the resin layer of 1.4 μm or less, the external additive is difficult to adhere to or embed in the resin layer of the carrier after transferring from the toner particle surface to the carrier surface, and the amount of external additive transferred from the toner to the carrier is reduced. It is presumed that this suppresses the increase in toner aggregation and suppresses the occurrence of toner aggregation.
The average thickness of the resin layer may be controlled by adjusting the amount of resin used to form the resin layer, and the larger the amount of resin relative to the amount of magnetic particles, the thicker the average thickness of the resin layer.

(Carrier characteristics)
The ratio B/A of the planar area A to the surface area B when three-dimensionally analyzing the surface of the carrier is 1.020 or more and 1.100 or less, and 1.040 or more and 1.080 or less. It is preferably 1.040 or more and 1.070 or less.
When the ratio B/A is 1.020 or more, the carrier surface has fine irregularities and the contact between the carrier and toner is point contact, which alleviates the mechanical load on the toner and reduces external additives to the toner. This prevents the agent from being buried in the toner particles. Therefore, it is presumed that the occurrence of toner aggregation is suppressed.
When the ratio B/A is 1.100 or less, the interval between the fine irregularities on the carrier surface is not too narrow, and the difference in height between the fine irregularities on the carrier surface is not relatively large, so that the external additive of the toner is absorbed into the carrier. It becomes difficult for the external additive to enter the recesses on the surface, and an increase in the amount of external additive transferred from the tor to the carrier is suppressed. Further, since the fine irregularities on the surface of the carrier are not too dense, the carrier and the toner are in point contact, the mechanical load on the toner is alleviated, and the embedding of the external additive is suppressed. Therefore, it is presumed that toner aggregation is suppressed.

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

The exposed area ratio of the magnetic particles on the carrier surface is preferably 5% or more and 30% or less, more preferably 7% or more and 25% or less, and even more 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 resin used to form the resin layer, and the larger the amount of resin relative to the amount of magnetic particles, the smaller the exposed area ratio.

The exposed area ratio of magnetic particles on the carrier surface is a value determined by the following method.
A target carrier and magnetic particles obtained by removing the resin layer from the target carrier are prepared. Examples of methods for removing the resin layer from the carrier include a method in which the resin layer is removed by dissolving the resin component with an organic solvent, a method in which the resin layer is removed by dissolving the resin component by heating to about 800°C, and the like. . Using the carrier and magnetic particles as measurement samples, quantify the Fe concentration (atomic%) on the sample surface by XPS, calculate (Fe concentration of carrier) ÷ (Fe concentration of magnetic particles) x 100, and calculate the Fe concentration (atomic%) of the magnetic particles. Expressed as exposed area rate (%).

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 even more preferably 30 μm or more and 80 μm or less.
Here, the volume average particle size means a particle size D50v that is cumulatively 50% from the small diameter side in the volume-based particle size distribution.

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

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

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

The image forming apparatus according to this embodiment is a direct transfer type device that directly transfers a toner image formed on the surface of an image carrier to a recording medium; a toner image formed on the surface of an image carrier is transferred to an intermediate transfer member. Intermediate transfer type device that performs primary transfer on the surface and secondary transfer of the toner image transferred to the surface of the intermediate transfer member onto the surface of the recording medium; After transferring the toner image, cleans the surface of the image carrier before charging. A known image forming apparatus is applied, such as an apparatus equipped with a cleaning means; an apparatus equipped with a static elimination means that irradiates the surface of the image carrier with static elimination light to eliminate static electricity after the toner image is transferred and before charging.
When the image forming apparatus according to the present embodiment is an intermediate transfer type apparatus, the transfer means includes, for example, an intermediate transfer body onto which a toner image is transferred, and a toner image formed on the surface of an image carrier. A configuration is applied that includes a primary transfer device that primarily transfers the toner image onto the surface of the intermediate transfer body, and a secondary transfer device that secondary transfers the toner image transferred to the surface of the intermediate transfer body onto the surface of the recording medium.

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

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

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

An intermediate transfer belt (an example of an intermediate transfer body) 20 extends above each unit 10Y, 10M, 10C, and 10K through each unit. The intermediate transfer belt 20 is provided so as to be wound around a drive roll 22 and a support roll 24, and runs in a direction from the first unit 10Y to the fourth unit 10K. A force is applied to the support roll 24 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 both of the support rolls 24 . An intermediate transfer member cleaning device 30 is provided on the side surface of the image carrier of the intermediate transfer belt 20 so as to face the drive roll 22 .
Developing devices (an example of developing means) of each unit 10Y, 10M, 10C, and 10K 4Y, 4M, 4C, and 4K each have yellow, magenta, cyan, and black toner cartridges housed in toner cartridges 8Y, 8M, 8C, and 8K. Each toner is supplied.

Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration and operation, here, the first to fourth units 10Y, 10M, 10C, and 10K, which form a yellow image, are disposed on the upstream side in the traveling direction of the intermediate transfer belt. The unit 10Y will be explained as a representative.

The first unit 10Y has a photoreceptor 1Y that acts as an image carrier. Around the photoreceptor 1Y, there is a charging roll (an example of charging means) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, and the charged surface is exposed to a laser beam 3Y based on a color-separated image signal. an exposure device (an example of an electrostatic image forming means) 3, a developing device (an example of a developing means) 4Y, which supplies charged toner to an electrostatic image and develops the electrostatic image; A primary transfer roll 5Y (an example of a primary transfer means) that transfers a toner image onto the intermediate transfer belt 20, and a photoreceptor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoreceptor 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 photoreceptor 1Y. A bias power source (not shown) for applying a primary transfer bias is connected to the primary transfer rolls 5Y, 5M, 5C, and 5K of each unit. Each bias power supply changes the value of the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

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

An electrostatic charge image is an image formed on the surface of the photoconductor 1Y due to electrical charging, and the laser beam 3Y reduces the specific resistance of the irradiated portion of the photoconductor layer, causing the charged charges on the surface of the photoconductor 1Y to flow. , on the other hand, is a so-called negative latent image formed by residual charges in areas not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoreceptor 1Y rotates to a predetermined development position as the photoreceptor 1Y travels. At this developing position, the electrostatic charge image on the photoreceptor 1Y is developed and visualized as a toner image by the developing device 4Y.

The developing device 4Y contains, for example, an electrostatic image developer containing at least yellow toner and carrier. The yellow toner is triboelectrically charged by being stirred inside the developing device 4Y, and has an electric charge of the same polarity (negative polarity) as the electric charge charged on the photoreceptor 1Y, and is transferred to the developer roll (developer holder). An example) is held on top. Then, as the surface of the photoreceptor 1Y passes through the developing device 4Y, yellow toner electrostatically adheres to the latent image area on the surface of the photoreceptor 1Y from which the static electricity has been removed, and the latent image is developed with the yellow toner. Ru. The photoconductor 1Y on which the yellow toner image has been formed continues to travel 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 electrostatic force from the photoconductor 1Y toward the primary transfer roll 5Y acts on the toner image, causing the photoconductor 1Y to transfer to the primary transfer position. The toner image on body 1Y is transferred onto intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the toner polarity (-), and is controlled to, for example, +10 μA by a control section (not shown) in the first unit 10Y.
On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

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

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

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

Examples of the recording paper P on which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, and the like. In addition to the recording paper P, examples of the recording medium include OHP sheets and the like.
In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper in which the surface of plain paper is coated with resin or the like, art paper for printing, etc. Preferably used.

The recording medium is not particularly limited, and in this embodiment, an image with suppressed gloss unevenness is formed even on a thin recording medium. Thin recording media are more affected by heat during image fixation than thick recording media, and images are more likely to have uneven gloss due to toner aggregates. However, in this embodiment, since the carrier is used and toner aggregates are less likely to occur, uneven gloss is suppressed even in images formed on thin recording media.
The thickness of the recording medium is, for example, in the range of 10 μm or more and 200 μm or less, preferably in the range of 15 μm or more and 150 μm or less, and more preferably in the range of 20 μm or more and 100 μm or less.
Further, when the recording medium is recording paper, the basis weight of the recording paper is, for example, in the range of 5 g/m ² or more and 150 g/m ² or less, and in the range of 8 g/m ² or more and 120 g/m ² or less. Preferably, the range is 10 g/m ² or more and 100 g/m ² or less.

The recording paper P on which the color image has been fixed is carried out toward the discharge section, and the 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 has a developing means for developing the electrostatic charge image formed on the surface of the image carrier as a toner image using the electrostatic charge image developer. This is a process cartridge that can be attached to and removed from an image forming apparatus.

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

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

FIG. 2 is a schematic configuration diagram showing the process cartridge according to this embodiment.
The process cartridge 200 shown in FIG. 2 is equipped with a photoconductor 107 (an example of an image holder) and the periphery of the photoconductor 107, for example, by a housing 117 equipped with a mounting rail 116 and an opening 118 for exposure. The charging roll 108 (an example of a charging means), the developing device 111 (an example of a developing means), and the photoreceptor cleaning device 113 (an example of a cleaning means) are integrally combined and held, and are formed into a cartridge. There is.
In FIG. 2, 109 is an exposure device (an example of an electrostatic 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). It shows.

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 the particle size D50v that is cumulatively 50% from the small diameter side in the volume-based particle size distribution.

[Preparation of toner]
<Preparation of amorphous polyester resin dispersion (A1)>
・Ethylene glycol: 37 parts ・Neopentyl glycol: 65 parts ・1,9-nonanediol: 32 parts ・Terephthalic acid: 96 parts The above materials were placed in a flask, and the temperature was raised to 200°C over 1 hour, and the inside of the reaction system was After confirming that the mixture was stirred uniformly, 1.2 parts of dibutyltin oxide was added. The temperature was raised to 240°C over 6 hours while distilling off the water produced, and stirring was continued at 240°C for 4 hours to produce an amorphous polyester resin (acid value 9.4 mgKOH/g, weight average molecular weight 13,000, A glass transition temperature of 62°C was obtained. The amorphous polyester resin was transferred in a molten state to an emulsifying and dispersing machine (Cavitron CD1010, Eurotech) at a rate of 100 g/min. Separately, add 0.37% diluted ammonia water, which is obtained by diluting the reagent ammonia water with ion-exchanged water, into a tank and heat the amorphous polyester resin at a rate of 0.1 liters per minute while heating it to 120°C with a heat exchanger. At the same time, it was transferred to an emulsification disperser. The emulsifying disperser was operated at 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 diameter of 160 nm and a solid content of 20% by mass.

<Preparation of crystalline polyester resin dispersion (C1)>
・Dodecanedioic acid: 81 parts ・Hexanediol: 47 parts The above materials were charged into a flask, the temperature was raised to 160°C over 1 hour, and after confirming that the reaction system was stirred uniformly, dibutyltin oxide was added. 0.03 part of was added. The temperature was raised to 200°C over 6 hours while distilling off the produced water, and stirring was continued at 200°C for 4 hours. Next, the reaction solution was cooled, solid-liquid separation was performed, and the solid material was dried at a temperature of 40° C./under reduced pressure to obtain a crystalline polyester resin (C1) (melting point: 75° C., weight average molecular weight: 15,000).

・Crystalline polyester resin (C1): 50 parts ・Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 2 parts ・Ion exchange water: 200 parts The above materials were heated to 120°C. The mixture was sufficiently dispersed using a homogenizer (Ultra Turrax T50, IKA), and then subjected to a dispersion treatment using a pressure discharge type homogenizer. When the volume average particle diameter reached 180 nm, the particles were collected to obtain a crystalline polyester resin dispersion (C1) with a solid content of 20% by mass.

<Preparation of crystalline polyester resin dispersion (C2)>
・Decanedioic acid: 81 parts ・Hexanediol: 47 parts Charge the above materials into a flask, raise the temperature to 160°C over 1 hour, and after confirming that the reaction system is uniformly stirred, add dibutyltin oxide. 0.03 part of was added. The temperature was raised to 200°C over 6 hours while distilling off the produced water, and stirring was continued at 200°C for 4 hours. Next, the reaction solution was cooled, solid-liquid separation was performed, and the solid material was dried at a temperature of 40° C./under reduced pressure to obtain a crystalline polyester resin (C2) (melting point: 67° C., weight average molecular weight: 15,000).

A crystalline polyester resin dispersion (C1) with a solid content of 20% by mass was prepared in the same manner as the crystalline polyester resin dispersion (C1) except that the crystalline polyester resin (C2) was used instead of the crystalline polyester resin (C1). C2) was obtained.

<Preparation of crystalline polyester resin dispersion (C3)>
・Dodecanedioic acid: 81 parts ・Ethylene glycol: 47 parts Charge the above materials into a flask, raise the temperature to 160°C over 1 hour, and after confirming that the reaction system is uniformly stirred, dibutyltin oxide 0.03 part of was added. The temperature was raised to 200°C over 6 hours while distilling off the produced water, and stirring was continued at 200°C for 4 hours. Next, the reaction solution was cooled, solid-liquid separation was performed, and the solid material was dried at a temperature of 40° C./under reduced pressure to obtain a crystalline polyester resin (C3) (melting point: 86° C., weight average molecular weight: 15,000).

A crystalline polyester resin dispersion (C1) with a solid content of 20% by mass was prepared in the same manner as the crystalline polyester resin dispersion (C1) except that the crystalline polyester resin (C3) was used instead of the crystalline polyester resin (C1). C3) was obtained.

<Preparation of crystalline polyester resin dispersion (C4)>
・Octanedioic acid: 81 parts ・Ethylene glycol: 47 parts Charge the above materials into a flask, raise the temperature to 160°C over 1 hour, and after confirming that the reaction system is uniformly stirred, add dibutyltin oxide. 0.03 part of was added. The temperature was raised to 200°C over 6 hours while distilling off the produced water, and stirring was continued at 200°C for 4 hours. Next, the reaction solution was cooled, solid-liquid separation was performed, and the solid material was dried at a temperature of 40° C./under reduced pressure to obtain a crystalline polyester resin (C4) (melting point: 63° C., weight average molecular weight: 15,000).

A crystalline polyester resin dispersion (C1) with a solid content of 20% by mass was prepared in the same manner as the crystalline polyester resin dispersion (C1) except that the crystalline polyester resin (C4) was used instead of the crystalline polyester resin (C1) C4) was obtained.

<Preparation of crystalline polyester resin dispersion (C5)>
- Phthalic acid: 81 parts - Nonanediol: 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 reaction system was stirred uniformly, dibutyltin oxide was added. 0.03 part was added. The temperature was raised to 200°C over 6 hours while distilling off the produced water, and stirring was continued at 200°C for 4 hours. Next, the reaction solution was cooled, solid-liquid separation was performed, and the solid material was dried at a temperature of 40° C./under reduced pressure to obtain a crystalline polyester resin (C5) (melting point: 91° C., weight average molecular weight: 15,000).

A crystalline polyester resin dispersion (C1) with a solid content of 20% by mass was prepared in the same manner as the crystalline polyester resin dispersion (C1) except that the crystalline polyester resin (C5) was used instead of the crystalline polyester resin (C1). C5) was obtained.

<Preparation of release agent particle dispersion (W1)>
・Paraffin wax (HNP-9 manufactured by Nippon Seiro Co., Ltd.): 100 parts ・Anionic surfactant (Neogen RK manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part ・Ion exchange water: 350 parts Above materials were mixed and heated to 100°C, dispersed using a homogenizer (Ultra Turrax T50 manufactured by IKA), and then subjected to dispersion treatment using a pressure-discharge type Gorlin homogenizer to disperse mold release agent particles with a volume average particle diameter of 200 nm. A release agent particle dispersion was obtained. Ion-exchanged water was added to this mold release agent particle dispersion to adjust the solid content to 20% by mass to obtain a mold release agent particle dispersion (W1).

<Preparation of colorant particle dispersion (K1)>
・Carbon black (manufactured by Cabot, Regal 330): 50 parts ・Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts ・Ion exchange water: 195 parts The above materials were mixed and the mixture was heated under high pressure. Dispersion treatment was performed for 60 minutes using an impact dispersion machine (Ultimizer HJP30006, Sugino Machine Co., Ltd.) to obtain a colorant particle dispersion (K1) with a solid content of 20%.

<Preparation of toner particles (K1)>
・Ion exchange water: 200 parts ・Amorphous polyester resin dispersion (A1): 375 parts ・Crystalline polyester resin dispersion (C1): 50 parts ・Release agent particle dispersion (W1): 50 parts ・Coloring agent Particle dispersion liquid (K1): 25 parts Anionic surfactant (TaycaPower): 2.8 parts Put the above materials into a round stainless steel flask, and add 0.1N nitric acid to adjust the pH to 3.5. After the adjustment, an aqueous polyaluminum chloride solution 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 Turrax T50 manufactured by IKA), the mixture was heated to 45° C. in a heating oil bath and maintained until the volume average particle diameter became 4.9 μm. Next, 60 parts of the amorphous polyester resin dispersion (A1) was added and held for 30 minutes. Next, when the volume average particle diameter reached 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 (Chrest 70, manufactured by Chrest Co., Ltd.) was added, and a 1N aqueous sodium hydroxide solution was added to adjust the pH to 9.0. Next, 1 part of an anionic surfactant (Tayca Power) was added, and while stirring was continued, the mixture was heated to 85° C. and maintained for 5 hours. Then, it was cooled to 20°C at a rate of 20°C/min. Next, the toner particles (K1) having a volume average particle diameter of 5.7 μm and an average circularity of 0.971 were obtained by filtering, thoroughly washing with ion-exchanged water, and drying.
Note that the content of the crystalline polyester (C1) based on the entire toner particles (K1) was 10% by mass.

<Preparation of toner (K1)>
100 parts by mass of toner particles (K1) and 1.5 parts by mass of hydrophobic silica particles (external additive, manufactured by Nippon Aerosil Co., Ltd., RY50, average particle size: 40 nm) were placed in a sample mill, and the mixture was heated at a rotation speed of 10,000 rpm for 30 seconds. Mixed. Next, the toner (K1) having a volume average particle diameter of 5.7 μm was obtained by sieving using a vibrating sieve with an opening of 45 μm. The 1/2 drop temperature of the flow tester was 105°C.

<Preparation of toner particles (K2) and toner (K2)>
Toner particles (K2) were prepared in the same manner as toner particles (K1) and toner (K1), except that 75 parts of crystalline polyester resin dispersion (C2) was added instead of 10 parts of crystalline polyester resin dispersion (C1). ) and toner (K2) were obtained.
Note that the content of crystalline polyester (C2) based on the entire toner particles (K2) was 14.3% by mass. The 1/2 drop temperature of the flow tester was 95°C.

<Preparation of toner particles (K3) and toner (K3)>
Toner particles (K3) were prepared in the same manner as toner particles (K1) and toner (K1) except that 35 parts of crystalline polyester resin dispersion (C3) was added instead of 10 parts of crystalline polyester resin dispersion (C1). ) and toner (K3) were obtained.
Note that the content of crystalline polyester (C3) based on the entire toner particles (K3) was 7.2% by mass. The 1/2 drop temperature of the flow tester was 135°C.

<Preparation of toner particles (K4) and toner (K4)>
Toner particles (K4) were prepared in the same manner as toner particles (K1) and toner (K1), except that 125 parts of crystalline polyester resin dispersion (C4) was added instead of 10 parts of crystalline polyester resin dispersion (C1). ) and toner (K4) were obtained.
Note that the content of crystalline polyester (C4) based on the entire toner particles (K4) was 21.7% by mass. The 1/2 drop temperature of the flow tester was 85°C.

<Preparation of toner particles (K5) and toner (K5)>
Toner particles (K5) were prepared in the same manner as toner particles (K1) and toner (K1) except that 25 parts of crystalline polyester resin dispersion (C5) was added instead of 10 parts of crystalline polyester resin dispersion (C1). ) and toner (K5) were obtained.
Note that the content of crystalline polyester (C5) based on the entire toner particles (K5) was 5.2% by mass. The 1/2 drop temperature of the flow tester was 145°C.

[Preparation of carrier]
<Preparation of ferrite particles (1)>
1318 parts of Fe ₂ O ₃ , 587 parts of Mn(OH) ₂ , and 96 parts of Mg(OH) ₂ were mixed and pre-calcined at a temperature of 900° C. for 4 hours. The calcined product, 6.6 parts of polyvinyl alcohol, 0.5 parts of polycarboxylic acid as a dispersant, and zirconia beads with a media diameter of 1 mm were placed in water, and the mixture was ground and mixed with a sand mill to form a dispersion. 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 using a spray dryer to obtain granules having a volume average particle diameter of 37 μm. Next, under an oxygen-nitrogen mixed atmosphere with an oxygen partial pressure of 1%, main firing was performed using an electric furnace at a temperature of 1450°C for 4 hours, and then heating was performed in the air at a temperature of 900°C for 3 hours. Calcined particles were obtained. The fired particles were crushed and classified to obtain ferrite particles (1) having a volume average particle diameter of 35 μm. The arithmetic mean height Ra (JIS B0601:2001) of the roughness curve of the ferrite particles (1) was 0.6 μm.

<Silica particles (1)>
As the silica particles (1), commercially available hydrophobic silica particles (vapor phase silica particles surface-treated with hexamethyldisilazane) manufactured by Tokuyama Co., Ltd., product name: Rheolosil HM20S, average primary particle size: 12 nm) were prepared.

<Silica particles (2)>
(Preparation of silica particle dispersion (2))
890 parts of methanol and 210 parts of 9.8% aqueous ammonia were added to a 1.5 L glass reaction vessel equipped with a stirrer, a dropping nozzle, and a thermometer and mixed to obtain an alkaline catalyst solution.
After adjusting the alkaline catalyst solution to 46°C, 550 parts of tetramethoxysilane and 140 parts of 7.6% aqueous ammonia were simultaneously added dropwise over 450 minutes while stirring. A silica particle dispersion liquid (2) in which silica particles were dispersed was obtained.

(Preparation of silica particles (2))
Using the silica particle dispersion (2), silica particles were subjected to surface treatment with a siloxane compound in a supercritical carbon dioxide atmosphere as shown below. For the surface treatment, an apparatus equipped with a carbon dioxide cylinder, a carbon dioxide pump, an entrainer pump, an autoclave with a stirrer (capacity 500 ml), and a pressure valve was used.
First, 300 parts of the silica particle dispersion (2) was put into an autoclave equipped with a stirrer (capacity: 500 ml), and the stirrer was rotated at 100 rpm. Thereafter, liquefied carbon dioxide was injected into the autoclave, and while the temperature was raised by a heater, the pressure was increased by a carbon dioxide pump to bring the inside of the autoclave into a supercritical state at 150° C. and 15 MPa. While maintaining the inside of the autoclave at 15 MPa with a pressure valve, supercritical carbon dioxide is passed from a carbon dioxide pump to remove methanol and water from the silica particle dispersion (2) (solvent removal step), and remove silica particles (untreated silica particles). ) was obtained.

Next, when the amount of distributed supercritical carbon dioxide (accumulated amount: measured as the amount of distributed carbon dioxide in a standard state) reached 900 parts, the distribution of supercritical carbon dioxide was stopped.
Thereafter, the temperature was maintained at 150°C by a heater, the pressure was maintained at 15 MPa by a carbon dioxide pump, and the supercritical state of carbon dioxide was maintained in the autoclave. After injecting 100 parts of hexamethyldisilazane (HMDS: manufactured by Organic Chemical Industry Co., Ltd.) as a hydrophobizing agent into the autoclave using an entrainer pump, the autoclave was reacted for 20 minutes at 180° C. with stirring. Thereafter, supercritical carbon dioxide was passed through again to remove excess processing agent solution. Thereafter, stirring was stopped, the pressure valve was opened to release the pressure inside the autoclave to atmospheric pressure, and the temperature was lowered to room temperature (25°C).
In this way, the solvent removal step and the surface treatment with a siloxane compound were performed in sequence to obtain silica particles (2), which were surface-treated silica particles.

<Silica particles (3)>
As the silica particles (3), commercially available hydrophobic silica particles (vapor phase silica particles surface-treated with dimethyl silicone oil, manufactured by Tokuyama Co., Ltd., product name: PM09, average primary particle size: 60 nm) were prepared.

<Silica particles (4)>
Silica particles (4) surface-treated with hexamethyldisilazane were obtained in the same manner as in the preparation of silica particles (2) except that the temperature of the alkali catalyst solution was changed to 35°C. The silica particles (4) had an average primary particle size of 75 nm.

<Silica particles (5)>
As the silica particles (5), commercially available hydrophobic silica particles (vapor phase silica particles surface-treated with hexamethyldisilazane, manufactured by Nippon Aerosil Co., Ltd., product name: RX50, average primary particle size: 85 nm) were prepared.

<Silica particles (6)>
Silica particles (6) surface-treated with hexamethyldisilazane were obtained in the same manner as in the preparation of silica particles (2), except that the temperature of the alkali catalyst solution was changed to 45°C. The silica particles (6) had an average primary particle size of 2 nm.

<Preparation of carrier (1)>
- Ferrite particles (1): 100 parts - Toluene 10 parts - Styrene/methyl methacrylate copolymer (copolymerization ratio 15 mol: 85 mol): 0.8 part - Cyclohexyl methacrylate/methyl methacrylate copolymer (copolymerization ratio 95 Moles: 5 moles): 0.8 parts, carbon black: 0.08 parts, silica particles (1): 0.9 parts Among the above materials, styrene/methyl methacrylate copolymer and cyclohexyl methacrylate/methyl methacrylate copolymer The combination, silica particles (1), toluene, and glass beads (1 mm in diameter, the same amount as toluene) were put into a sand mill (Kansai Paint Co., Ltd.), stirred at a rotation speed of 1200 rpm for 30 minutes, and the resin liquid for forming a resin layer (1 ). The ferrite particles (1) were placed in a vacuum degassing type kneader, and then half of the resin liquid for forming a resin layer (1) was added thereto, and the temperature was raised to 70° C. while stirring at 40 rpm, and maintained for 15 minutes. Thereafter, the pressure was reduced over 30 minutes to distill off toluene. Thereafter, the mixture was cooled to room temperature (25°C), and the remaining half of the resin layer-forming resin liquid (1) was added thereto, and the mixture was heated to 70°C while stirring at 40 rpm, and mixed for 20 minutes. Thereafter, the pressure was reduced over 30 minutes to distill off toluene. Next, fine powder and coarse powder were removed using an elbow jet to obtain carrier (1), which was a resin-coated carrier.

<Preparation of carrier (2)>
Using 0.6 parts of silica particles (5) instead of 0.9 parts of silica particles (1), and adding 0.9 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer The amount of addition was 0.9 parts, and the second mixing time (i.e., the time for adding the remaining half of the resin layer forming resin liquid (1) and heating it to 70°C while stirring at 40 rpm and mixing) was 20 minutes. Carrier (2) was obtained in the same manner as carrier (1) except that the time was changed to 40 minutes.

<Preparation of carrier (3)>
Using 1.1 parts of silica particles (2) instead of 0.9 parts of silica particles (1), and adding 0.8 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer The amount of addition was 0.8 part, and the second mixing time (i.e., the time for adding the remaining half of the resin layer forming resin liquid (1) and heating it to 70°C while stirring at 40 rpm and mixing) was 20 minutes. Carrier (3) was obtained in the same manner as carrier (1) except that the time was changed to 15 minutes.

<Preparation of carrier (4)>
Using 0.8 parts of silica particles (3) instead of 0.9 parts of silica particles (1), and adding 0.9 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer The amount of addition was 0.9 parts, and the second mixing time (i.e., the time for adding the remaining half of the resin layer forming resin liquid (1) and heating it to 70°C while stirring at 40 rpm and mixing) was 20 minutes. Carrier (4) was obtained in the same manner as carrier (1) except that the time was changed to 30 minutes.

<Preparation of carrier (5)>
Using 1.0 part of silica particles (4) instead of 0.9 parts of silica particles (1), and adding 0.8 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer The amount of addition was 0.8 parts, and the second mixing time (i.e., the time for adding the remaining half of the resin layer forming resin liquid (1) and heating it to 70°C while stirring at 40 rpm and mixing) was 20 minutes. Carrier (5) was obtained in the same manner as Carrier (1) except that the time was changed to 35 minutes.

<Preparation of carrier (6)>
Using 0.4 parts of silica particles (1) instead of 0.9 parts of silica particles (1), and adding 0.6 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer Carrier (6) was obtained in the same manner as Carrier (1) except that the amount added was changed to 0.6 parts.

<Preparation of carrier (7)>
Using 1.4 parts of silica particles (1) instead of 0.9 parts of silica particles (1), and adding 1.0 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer Carrier (7) was obtained in the same manner as Carrier (1) except that the amount added was changed to 1.0 part.

<Preparation of carrier (8)>
Using 0.8 parts of silica particles (1) instead of 0.9 parts of silica particles (1), and adding 0.7 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer Carrier (8) was obtained in the same manner as Carrier (1) except that the amount added was changed to 0.7 parts.

<Preparation of carrier (9)>
Using 1.1 parts of silica particles (1) instead of 0.9 parts of silica particles (1), and adding 0.9 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer Carrier (9) was obtained in the same manner as Carrier (1) except that the amount added was changed to 0.9 parts.

<Preparation of carrier (10)>
Except that silica particles (1) were not added, and the amount of styrene/methyl methacrylate copolymer added was changed to 1.1 parts, and the amount of cyclohexyl methacrylate/methyl methacrylate copolymer added was changed to 1.1 parts. Carrier (10) was obtained in the same manner as carrier (1).

<Preparation of carrier (11)>
Using 0.8 parts of silica particles (6) instead of 0.9 parts of silica particles (1), and adding 0.8 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer The amount of addition was 0.8 part, and the second mixing time (i.e., the time for adding the remaining half of the resin layer forming resin liquid (1) and heating it to 70°C while stirring at 40 rpm and mixing) was 20 minutes. Carrier (11) was obtained in the same manner as carrier (1) except that the time was changed to 10 minutes.

<Preparation of carrier (12)>
Using 0.2 parts of silica particles (1) instead of 0.9 parts of silica particles (1), and adding 0.3 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer Carrier (12) was obtained in the same manner as Carrier (1) except that the amount added was changed to 0.3 parts.

<Preparation of carrier (13)>
Using 1.6 parts of silica particles (1) instead of 0.9 parts of silica particles (1), and adding 1.1 parts of styrene/methyl methacrylate copolymer, cyclohexyl methacrylate/methyl methacrylate copolymer Carrier (13) was obtained in the same manner as Carrier (1) except that the amount added was changed to 1.1 parts.

<Carrier measurement>
Regarding the obtained carrier, the ratio B/A ("ratio B/A" in Table 1), the average particle size of silica particles contained in the resin layer ("inorganic particle size" in Table 1), and the resin layer Table 1 shows the results of the average thickness ("film thickness" in Table 1) obtained by the method described above.

[Developer evaluation]
A4 size recording paper (manufactured by Fuji Xerox Co., Ltd., basis weight 64 g/m ² ) was used using a modified DocuCentreColor 400 (manufactured by Fuji Xerox Co., Ltd.) in an environment with a temperature of 28.5° C. and a humidity of 85%. After forming 10,000 sheets of halftone images with an image density of 10%, images with an image density of 100 were printed on A4-sized thin recording paper (manufactured by Fuji Xerox Co., Ltd., ST paper, thickness 78 μm, basis weight 54 g/m ² ). % images were formed, and 60 degree gloss was measured at 10 points using a gloss meter (BYK Micro Trigloss Gloss Meter (20+60+85°), manufactured by Gardner). Gloss unevenness was evaluated from the difference in glossiness at the 10 points (maximum value - minimum value) and standard deviation. Moreover, the evaluation criteria are as follows.

<Evaluation criteria>
A: The difference in gloss is less than 5% and the standard deviation of 10 points of gloss measurement is 2 or less B: The difference in gloss is less than 5% and the standard deviation of 10 points of gloss measurement is more than 2 C: The difference in gloss is 5% D: Difference in gloss is 7.5% or more and less than 10% E: Difference in gloss is 10% or more

As shown in the table above, it can be seen that uneven gloss in images is suppressed in Examples compared to Comparative Examples.

1Y, 1M, 1C, 1K photoreceptor (an example of image carrier)
2Y, 2M, 2C, 2K Charging roll (an example of charging means)
3 Exposure device (an example of electrostatic image forming means)
3Y, 3M, 3C, 3K Laser beam 4Y, 4M, 4C, 4K Developing device (an example of developing means)
5Y, 5M, 5C, 5K Primary transfer roll (an example of primary transfer means)
6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt (an example of intermediate transfer body)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
28 Fixing device (an example of fixing means)
30 Intermediate transfer member cleaning device P Recording paper (an example of recording medium)
107 Photoreceptor (an example of an image carrier)
108 Charging roll (an example of charging means)
109 Exposure device (an example of electrostatic image forming means)
111 Developing device (an example of developing means)
112 Transfer device (an example of transfer means)
113 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 (16)

a toner having toner particles containing a crystalline resin and an external additive attached to the surface of the toner particles;
It has magnetic particles and a resin layer covering the magnetic particles and containing an alicyclic acrylic resin, inorganic particles , and carbon black , wherein the average particle size of the inorganic particles is 5 nm or more and 90 nm or less, and the average particle size of the resin layer is A carrier having a thickness of 0.6 μm or more and 1.4 μm or less, and a ratio B/A of planar area A to surface area B of 1.020 or more and 1.100 or less when the surface is three-dimensionally analyzed;
An electrostatic image developer having: The electrostatic image developer according to claim 1, wherein the toner particles contain an amorphous polyester resin and a crystalline polyester resin that is the crystalline resin. The arithmetic mean height Ra of the roughness curve of the magnetic particles is 0.1 μm or more and 1 μm or less,
The electrostatic image developer according to claim 1 or 2, wherein the content of the inorganic particles is 10% by mass or more and 60% by mass or less based on the total mass of the resin layer. The electrostatic image developer according to any one of claims 1 to 3 , wherein the ratio B/A is 1.040 or more and 1.080 or less. The electrostatic image developer according to claim 4 , wherein the ratio B/A is 1.050 or more and 1.080 or less. The electrostatic image developer according to any one of claims 1 to 5 , wherein the inorganic particles have an average particle size of 5 nm or more and 70 nm or less. The electrostatic image developer according to claim 6 , wherein the inorganic particles have an average particle size of 5 nm or more and 50 nm or less. The electrostatic image developer according to any one of claims 1 to 7 , wherein the average thickness of the resin layer is 0.8 μm or more and 1.2 μm or less. The electrostatic image developer according to any one of claims 1 to 8 , wherein the inorganic particles are silica particles. The electrostatic image developer according to any one of claims 1 to 9 , wherein the crystalline resin has a melting point of 65°C or more and 90°C or less. The electrostatic image developer according to any one of claims 1 to 10 , wherein the content of the crystalline resin is 5% by mass or more and 30% by mass or less based on the entire toner particles. The electrostatic image developer according to any one of claims 1 to 11 , wherein the 1/2 drop temperature of the flow tester of the toner is 90°C or more and 140°C or less. The electrostatic image developer according to any one of claims 1 to 12 , wherein the average particle size of the inorganic particles is 0.015 times or more and 10 times or less the average particle size of the external additive. The electrostatic charge image developer according to any one of claims 1 to 13 is stored, and the electrostatic charge image formed on the surface of the image carrier is developed as a toner image by the electrostatic charge image developer. Equipped with a developing means,
A process cartridge that can be attached to and removed from an image forming apparatus. an image holder;
Charging means for charging the surface of the image carrier;
an electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
The electrostatic charge image developer according to any one of claims 1 to 13 is contained, and the electrostatic charge image formed on the surface of the image carrier is developed as a toner image by the electrostatic charge image developer. a developing means for
a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
a fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising: a charging step of charging the surface of the image carrier;
an electrostatic charge image forming step of forming an electrostatic charge image on the surface of the charged image carrier;
A developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to any one of claims 1 to 13 ;
a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
a fixing step of fixing the toner image transferred to the surface of the recording medium;
An image forming method comprising: