JP7435705B2 - Toner for electrostatic image development, electrostatic image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method - Google Patents

Description

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

BACKGROUND ART Methods such as electrophotography that visualize image information through electrostatic charge images are currently used in various fields.
Conventionally, in electrophotography, an electrostatic latent image is formed on a photoconductor or an electrostatic recording medium using various means, and electrostatic particles called toner are attached to this electrostatic latent image to generate an electrostatic charge. A commonly used method is to develop a latent image (toner image), transfer it to the surface of a transfer target, and visualize it through multiple steps such as fixing by heating or the like.

Patent Document 1 discloses a developer containing a binder resin and a colorant, in which developer particles are suspended in an aqueous solution, and while this suspension is passed, the developer in the suspension is When the particles are captured as a still image and the equivalent circle diameter and circularity of the developer particles are determined from the projected area and perimeter of the particle image through image analysis, the 50% average diameter A and the 10% average diameter A of the developer particles are determined. A developer characterized in that the ratio B/A of average diameter B is 40 to 80%, the average circularity is 0.93 to 1.0, and the proportion of circularity of 0.85 or less is 3.0% or less. is disclosed.

Japanese Patent Application Publication No. 9-197714

The problems to be solved by the present invention are the occurrence of white spots in images and An object of the present invention is to provide a toner for developing electrostatic images that suppresses gloss unevenness.

Specific means for solving the above problems include the following aspects.
<1> An electrostatic image developing toner having a surface property index value expressed by the following formula S of 2.0 or more and 2.8 or less.
(Surface property index value) = (Actual measured value of specific surface area) / (Calculated value of specific surface area) Formula S
(Specific surface area calculation value) = (sum of surface areas calculated from circle-equivalent diameters of 4500 toner particles in flow particle image analysis)/{(specific gravity of toner) Sum of volumes calculated from circle equivalent diameter)}
<2> The toner for developing an electrostatic image according to <1>, which contains a binder resin and a release agent.
<3> When the number of release agents in the toner having an aspect ratio of 5 or more is a, and the number of release agents below 5 is b, then 1.0<a/b<8.0 according to <2> Toner for developing electrostatic images.
<4> Described in <3> where 1.0<c/d<4.0, where c is the area in the cross section of the toner particle where the aspect ratio of the release agent is 5 or more, and d is the area below 5. Toner for developing electrostatic images.
<5> The toner for developing an electrostatic image according to any one of <2> to <4>, wherein the releasing agent has a melting temperature of 65° C. or higher and 100° C. or lower.
<6> The toner for developing an electrostatic image according to <5>, wherein the releasing agent has a melting temperature of 70° C. or more and 95° C. or less.
<7> The toner for developing an electrostatic image according to any one of <1> to ^<6> , wherein the toner has a melt viscosity of 90° C. or more and 140° C. or less as measured by a flow tester method at a load of 10 kgf/cm 2 toner.
<8> The toner for developing an electrostatic image according to <7>, wherein the toner has a melt viscosity of 95° C. or more and 130° C. or less as measured by a flow tester method at a load of 10 kgf/cm ² .
<9> An electrostatic image developer comprising the toner for developing an electrostatic image according to any one of <1> to <8>.
<10> A toner cartridge that accommodates the toner for developing an electrostatic image according to any one of <1> to <8> and is detachable from an image forming apparatus.
<11> A developing device containing the electrostatic image developer according to <9> and developing an electrostatic image formed on the surface of an image carrier as a toner image by the electrostatic image developer, A process cartridge that can be attached to and removed from a forming device.
<12> 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 charged surface of the image carrier, and the electrostatic charge according to <9>. a developing means containing a charge image developer and developing an electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer; and a toner formed on the surface of the image carrier. An image forming apparatus comprising: a transfer unit that transfers an image to the surface of a recording medium; and a fixing unit that fixes the toner image transferred to the surface of the recording medium.
<13> A charging step of charging the surface of the image carrier, an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier, and the electrostatic image developer according to <9>, a developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image, a transfer step of transferring the toner image formed on the surface of the image carrier onto the surface of a recording medium, and the recording medium a fixing step of fixing the toner image transferred to the surface of the image forming method.

According to the inventions according to <1> to <4>, white spots in the image are less Provided is a toner for developing an electrostatic image that suppresses the occurrence of the phenomenon and uneven gloss of an image.
According to the invention according to <5>, there is provided a toner for developing an electrostatic image that suppresses uneven gloss of an image more than when the melting temperature of the release agent is lower than 65°C or higher than 100°C. Ru.
According to the invention according to <6>, there is provided a toner for developing electrostatic images that suppresses uneven gloss of images more than when the melting temperature of the release agent is less than 70°C or more than 95°C. Ru.
According to the invention according to <7> above, the occurrence of white spots in ^the image and the occurrence of white spots and Provided is a toner for developing electrostatic images that further suppresses uneven gloss of images.
According to the invention according to <8> above, the occurrence of white spots in images and the occurrence of white spots are reduced compared to when the melt viscosity of the toner measured by a flow tester method at a load of 10 kgf/cm ² is less than 95° C. or more than 130° C. Provided is a toner for developing electrostatic images that further suppresses uneven gloss of images.
According to the inventions according to <9> to <13>, an electrostatic image developing toner having a surface property index value represented by the formula S of less than 2.0 or more than 2.8 is applied. The present invention provides an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method that suppresses the occurrence of white spots in images and uneven gloss of images, compared to the case where the image is formed.

1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment. FIG. 1 is a schematic configuration diagram showing a process cartridge according to the present embodiment.

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, "toner for developing an electrostatic image" is also simply referred to as "toner", and "electrostatic image developer" is also simply referred to as "developer".

Hereinafter, an embodiment that is an example of the present invention will be described.

<Toner for electrostatic image development>
The electrostatic image developing toner according to the present embodiment has a surface property index value expressed by the following formula S of 2.0 or more and 2.8 or less.
(Surface property index value) = (Actual measured value of specific surface area) / (Calculated value of specific surface area) Formula S
(Specific surface area calculation value) = (sum of surface areas calculated from circle-equivalent diameters of 4500 toner particles in flow particle image analysis)/{(specific gravity of toner) Sum of volumes calculated from circle equivalent diameter)}

With conventional toners, external additives cannot be transferred due to the mechanical load within the developing means, and the surface of the toner base particles is less exposed. When a large amount of recording medium is printed, heat is absorbed by the recording medium and insufficient heat is applied to the toner, resulting in defective peeling, especially for tertiary colors, and white spots in the image.

Furthermore, as a method for checking the surface properties of toner for developing electrostatic images, methods such as measuring and calculating specific surface area using a Coulter counter are known, but a method using flow particle image analysis (FPIA) is better. There is.

The toner for developing an electrostatic image according to the present embodiment has the above-described structure, thereby suppressing the occurrence of white spots in the image and uneven gloss of the image. Although the reason is not certain, it is presumed as shown below.
When the surface property index value is 2.0 or more and 2.8 or less, the toner surface has moderate irregularities. The external additive is easily transferred due to the mechanical load within the developing means, and the surface of the toner base particles is likely to be exposed. Further, when a release agent is contained, the release agent tends to ooze out during fixing, so the fixing temperature can be particularly lowered. Therefore, even when printing on a recording medium with a high basis weight in a humid environment, peeling defects are suppressed, especially for tertiary colors, and as a result, white spots in the image are suppressed, and the toner surface is Since the structure is relatively uniform and the fixing behavior of the toner is also easily uniform, it is presumed that an electrostatic image developing toner with suppressed unevenness in image gloss can be obtained.

Hereinafter, the electrostatic image developing toner according to the present embodiment will be described in detail.

(Superficiality index value)
The electrostatic image developing toner according to the present embodiment has a surface property index value expressed by the following formula S of 2.0 or more and 2.8 or less.
(Surface property index value) = (Actual measured value of specific surface area) / (Calculated value of specific surface area) Formula S
Note that the actual measured value of the specific surface area of the toner in this embodiment is a value measured by a nitrogen adsorption method. Specifically, it is measured by a single point method of nitrogen adsorption method using the BET equation. Note that the equilibrium relative pressure is 0.3.

The specific surface area calculation value of the toner in this embodiment is calculated by the following formula.
(Specific surface area calculation value) = (sum of surface areas calculated from circle-equivalent diameters of 4500 toner particles in flow particle image analysis)/{(specific gravity of toner) Sum of volumes calculated from circle equivalent diameter)}
Flow particle image analysis (FPIA) in calculating the calculated specific surface area is performed using a flow particle image analyzer FPIA-3000 manufactured by Sysmex.
This device uses a flow-type particle image analysis method to measure particles dispersed in water, etc. The aspirated particle suspension is guided to a flat sheath flow cell, and the sheath liquid creates a flat sample flow. is formed. By irradiating the sample flow with strobe light, the passing particles are imaged as a still image by a CCD (Charge Coupled Device) camera through an objective lens. The captured particle image is subjected to two-dimensional image processing, and the equivalent circle diameter is calculated from the projected area. Regarding the equivalent circle diameter, image analysis is performed on each of the 4,500 toners, statistical processing is performed to obtain the equivalent circle diameter, and the sum of the surface areas calculated from the equivalent circle diameters of the 4,500 toners is calculated. The sum of the volumes calculated from the equivalent circle diameter of the toner is determined.
Note that for the measurement by the flow-type particle image analysis, HPF mode (high resolution mode) is used, and the dilution ratio is 1.0 times.
The specific gravity of the toner was determined by measuring the true specific gravity using a Gerussac type pycnometer in accordance with JIS-K-0061 8.2.2.

The surface property index value expressed by the formula S in the electrostatic image developing toner according to the present embodiment is 2.1 or more and 2.7 or less from the viewpoint of suppressing white spots in the image and suppressing gloss unevenness. It is preferably 2.2 or more and 2.6 or less, and particularly preferably 2.3 or more and 2.5 or less. Within the above range, the surface structure is relatively uniform, and the fixing behavior of the particles is also likely to be uniform. Therefore, it becomes easier to suppress the occurrence of uneven gloss.
The surface property index can be controlled by, for example, appropriately adjusting the temperature, pH, etc. when agglomerated particles containing resin particles are fused and coalesced.

The toner for developing an electrostatic image according to the present embodiment has a melt viscosity of 90° C. or higher and 140° C. or higher, measured by a flow tester method at a load of 10 kgf/cm ² , from the viewpoint of suppressing white spots in images and suppressing gloss unevenness. The temperature is preferably 95°C or higher and 130°C or lower, even more preferably 98°C or higher and 125°C or lower, and particularly preferably 105°C or higher and 115°C or lower.
The method for measuring the melt viscosity of the toner in this embodiment is to use a Koka type flow tester CFT-500 (manufactured by Shimadzu Corporation), with a die pore diameter of 0.5 mm and a pressure load of 10 kgf/cm. ^2. Under conditions where the temperature increase rate is 1° C./min, the viscosity at a temperature corresponding to 1/2 of the height from the start point to the end point when a 1 cm ³ sample is melted and flowed is determined.

The toner for developing an electrostatic image according to the present embodiment has an aluminum atom content of 0.005 kcps or more and 0.35 kcps or less as determined by fluorescent X-ray analysis from the viewpoint of suppressing white spots in images and suppressing gloss unevenness. It is preferably 0.02 kcps or more and 0.30 kcps or less, and particularly preferably 0.05 kcps or more and 0.20 kcps or less.
The method of measuring the aluminum atom content by X-ray fluorescence analysis in this embodiment is to analyze the content of aluminum atoms in the toner using an X-ray fluorescence analyzer (scanning X-ray fluorescence analyzer, ZSX Primus II, manufactured by Rigaku Co., Ltd.). The net strength of the aluminum atomic weight contained in was measured. In addition, as sample pretreatment, 0.1 g to 0.2 g of toner was molded into a disk by pressure molding, and the measurement conditions were qualitative and quantitative measurement, with a tube voltage of 40 kV, tube current of 70 mA, and measurement time of 15 minutes. .
The content of aluminum atoms in the toner is adjusted, for example, by using an aluminum aggregating agent used in the preparation of the toner.

The toner according to the present embodiment includes toner particles (also referred to as "toner base particles") and, if necessary, an external additive.

(toner particles)
The toner particles contain, for example, a binder resin, and if necessary, a colorant, a release agent, and other additives, and preferably contain the binder resin and the release agent.
In this embodiment, the toner particles may be, for example, toner particles such as yellow toner, magenta toner, cyan toner, and black toner, as well as white toner particles, transparent toner particles, glitter toner particles, etc. There are no restrictions.

-Binder resin-
Examples of the binder resin include styrenes (such as styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic esters (such as methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic acid). n-butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (for example, acrylonitrile, (methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), 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 binder resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosins, mixtures of these and the above-mentioned vinyl resins, or mixtures thereof. Also included are graft polymers obtained by polymerizing vinyl monomers in coexistence.
Among them, styrene acrylic resin is preferably used.
These binder resins may be used alone or in combination of two or more.

As the binder resin, polyester resin is suitable. Examples of polyester resins include condensation polymers of polyhydric carboxylic acids and polyhydric alcohols.

Examples of polycarboxylic acids include aliphatic dicarboxylic acids (eg, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid, etc.) , alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc.), anhydrides thereof, or lower grades thereof (e.g., carbon atoms with 1 or more carbon atoms). 5 or less) alkyl esters. Among these, as the polyhydric carboxylic acid, for example, aromatic dicarboxylic acids are preferable.
As the polyvalent carboxylic acid, a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure may be used in combination with the dicarboxylic acid. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, carbon atoms of 1 or more and 5 or less) 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 glass transition temperature (Tg) of the polyester resin is preferably 50°C or more and 80°C or less, more preferably 50°C or more and 65°C or less.
The glass transition temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC). It is determined by the outer glass transition start temperature.

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

Polyester resin can be obtained by a known manufacturing method. Specifically, it can be obtained, for example, by a method in which the polymerization temperature is set to 180° C. or higher and 230° C. or lower, and if necessary, the pressure inside the reaction system is reduced to allow the reaction to occur while removing water and alcohol generated during condensation.
If the raw material monomers are not dissolved or 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 recommended to condense the monomer with poor compatibility and the acid or alcohol to be polycondensed in advance before polycondensing it with the main component. .

The content of the binder resin is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and even more preferably 60% by mass or more and 85% by mass or less, based on the entire toner particles.
Further, when the toner particles are white toner particles, the content of the binder resin is preferably 30% by mass or more and 85% by mass or less, more preferably 40% by mass or more and 60% by mass or less, based on the entire white 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 release agent is preferably 50°C or more and 110°C or less, more preferably 65°C or more and 100°C or less, and 70°C from the viewpoint of suppressing white spots in images and suppressing gloss unevenness. The temperature is more preferably 95°C or higher, and particularly preferably 75°C or higher and 90°C or lower.
The melting temperature of the mold release agent is calculated from the DSC curve obtained by differential scanning calorimetry (DSC) and the "melting peak temperature" described in the method for determining the melting temperature of JIS K7121-1987 "Method for measuring transition temperature of plastics". demand.

In the toner for developing an electrostatic image of the present embodiment, from the viewpoint of suppressing white spots in images and suppressing gloss unevenness, the number of release agents in the toner with an aspect ratio of 5 or more is a, and the number of release agents with an aspect ratio of less than 5 is a. b, preferably 1.0<a/b<8.0, more preferably 2.0<a/b<7.0, and 3.0<a/b<6. It is particularly preferable that it be 0.
In addition, in the electrostatic image developing toner of the present embodiment, from the viewpoint of suppressing white spots in images and suppressing gloss unevenness, the area where the aspect ratio of the release agent is 5 or more in the toner cross section (toner particle cross section) is c. , when the area below 5 is d, it is preferable that 1.0<c/d<4.0, more preferably 1.5<a/b<3.5, and 2.0 It is particularly preferred that <a/b<3.0.

The aspect ratio of the release agent in the toner shall be measured by the following method.
The toner is mixed with the epoxy resin and the epoxy resin is solidified. The obtained solidified product is cut with an ultramicrotome device (UltracutUCT manufactured by Leica) to prepare a thin sample having a thickness of 80 nm or more and 130 nm or less. Next, the slice sample is stained with ruthenium tetroxide in a desiccator at 30° C. for 3 hours. Then, an SEM image of the stained thin section sample is obtained using an ultra-high resolution field emission scanning electron microscope (FE-SEM) (for example, S-4800 manufactured by Hitachi High-Technologies Corporation). In general, a mold release agent is more easily dyed by ruthenium tetroxide than a binder resin, so the mold release agent can be identified by the shading caused by the degree of dyeing. If it is difficult to distinguish shading due to the condition of the sample, adjust the staining time. Note that in a cross section of a toner particle, colorant domains are generally smaller than release agent domains, and therefore can be distinguished by size.
Since the SEM image includes toner particle cross sections of various sizes, toner particle cross sections whose diameter is 85% or more of the volume average particle diameter of the toner particles are selected, and 100 toner particles are randomly selected from among them. Select a particle cross section and observe it. Here, the diameter of the toner particle cross section refers to the maximum length (so-called major axis) drawn between arbitrary two points on the contour line of the toner particle cross section.
In the SEM image, image analysis is performed on each of the 100 toner particle cross sections selected as described above using image analysis software (WinROOF, manufactured by Mitani Shoji Co., Ltd.) under the condition of 0.010000 μm/pixel. Through this image analysis, it is possible to observe a cross-sectional image of the toner particles based on the brightness difference (contrast) between the epoxy resin used for embedding and the binder resin of the toner particles. Based on the observed image, the length of the release agent domain in the toner particle in the major axis direction, the ratio (length in the major axis direction/length in the minor axis direction), and area can be determined. .

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

-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, Pigments such as malachite green oxalate, titanium oxide, zinc oxide, calcium carbonate, basic lead carbonate, zinc sulfide-barium sulfate mixture, zinc sulfide, silicon dioxide, aluminum oxide; acridine series, xanthene series, azo series, benzoquinone series, Examples include azine-based, anthraquinone-based, thioindico-based, dioxazine-based, thiazine-based, azomethine-based, indico-based, phthalocyanine-based, aniline black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes.

Further, when the toner particles are white toner particles, a white pigment may be used as the colorant.
As the white pigment, titanium oxide and zinc oxide are preferred, and titanium oxide is more preferred.

One type of coloring agent may be used alone, or two or more types may be used in combination.

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

The content of the colorant is 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.
Further, when the toner particles are white toner particles, the content of the white pigment is preferably 15% by mass or more and 70% by mass or less, and more preferably 20% by mass or more and 60% by mass or less, based on the entire white toner particles.

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

-Characteristics of toner particles, etc.-
The toner particles may be toner particles with a single-layer structure, or may be toner particles with a so-called core-shell structure composed of a core part (core particle) and a coating layer (shell layer) covering the core part. It's okay. Toner particles having a core-shell structure are composed of, for example, a core containing a binder resin, a colorant, a mold release agent, etc. as necessary, and a coating layer containing the binder resin.

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 volume average particle diameter of the toner particles is measured using Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using ISOTON-II (manufactured by Beckman Coulter).
In the measurement, 0.5 mg or more and 50 mg or less of the measurement sample is added to 2 ml of a 5% by mass aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant. This is added to 100 ml or more and 150 ml or less of an electrolytic solution.
The electrolyte in which the sample was suspended was dispersed for 1 minute using an ultrasonic disperser, and each particle was separated using a Coulter Multisizer II using an aperture with an aperture diameter of 100 μm for particles with a particle size in the range of 2 μm to 60 μm. Measure the diameter. The number of particles to be sampled is 50,000.
For the measured particle diameters, a volume-based cumulative distribution is drawn from the small diameter side, and the particle diameter at which the cumulative distribution is 50% is defined as the volume average particle diameter D50v.

In this embodiment, the average circularity of the toner particles is not particularly limited, but from the viewpoint of improving the cleaning performance of the toner from the image carrier, it is preferably 0.91 or more and 0.98 or less, and 0.94 or more. It is more preferably 0.98 or less, and even more preferably 0.95 or more and 0.97 or less.

In this embodiment, the circularity of the toner particles is (perimeter of a circle having the same area as the particle projection image)÷(perimeter of the particle projection image), and the average circularity of the toner particles is the circularity of the toner particle. This is the cumulative circularity of 50% from the smallest side in the distribution. The average circularity of toner particles is determined by analyzing at least 3,000 toner particles using a flow type particle image analyzer.

The average circularity of toner particles can be controlled, for example, by adjusting the stirring speed of the dispersion, the temperature of the dispersion, or the holding time in the aggregation/coalescence process when toner particles are produced by an aggregation/coalescence method. .

(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 preferably 1 part by mass or more and 10 parts by mass or less, for example, 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.

The amount of the external additive added is, for example, preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 6% 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 (eg, kneading and pulverizing method) or a wet manufacturing method (eg, aggregation coalescence method, suspension polymerization method, dissolution/suspension method, etc.). There are no particular restrictions on these manufacturing methods, and known manufacturing methods may be employed. Among these, it is preferable to obtain toner particles by an aggregation coalescence method.

Specifically, for example, when toner particles are 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 process of agglomerating the resin particles (other particles as necessary) to form agglomerated particles (agglomerated particle formation process), heating the agglomerated particle dispersion in which the agglomerated particles are dispersed, and aggregation. Toner particles are manufactured through a step of fusing and coalescing 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, and the colorant and release agent are used as necessary. Of course, other additives than the colorant and mold release agent may be used.

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

The resin particle dispersion 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 surfactants based on surfactants, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly mentioned. Nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants.
One type of surfactant may be used alone, or two or more types may be used in combination.

In the resin particle dispersion, 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 a dispersion medium by a phase inversion emulsification method. The phase inversion emulsification method involves dissolving the resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, neutralizing it by adding a base to the organic continuous phase (O phase), and then dissolving it in an aqueous medium (W phase). ), the phase is inverted from W/O to O/W, and the resin is dispersed in the form of particles in an aqueous medium.

The volume average particle diameter of the resin particles dispersed in the resin particle dispersion is preferably, for example, 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and even more preferably 0.1 μm or more and 0.6 μm or less. preferable.
The volume average particle diameter of the resin particles is calculated 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, and the particle size that is cumulatively 50% of all particles is measured as the volume average particle size D50v. The volume average particle size of particles in other dispersions is similarly measured.

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

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

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

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

-Fusion/unification process-
Next, the agglomerated particle dispersion liquid in which the agglomerated particles are dispersed is heated, for example, at a temperature higher than the glass transition temperature of the resin particles (e.g., at a temperature higher than the glass transition temperature of the resin particles by 30 to 50 degrees Celsius) and at the melting temperature of the mold release agent. By heating above, the aggregated particles are fused and combined to form toner particles.
In the fusion/unification process, the resin and the mold release agent are in a fused state at a temperature higher than the glass transition temperature of the resin particles and higher than the melting temperature of the mold release agent. Thereafter, the toner is obtained by cooling.
Methods for adjusting the aspect ratio of the release agent in the toner include maintaining the temperature around the freezing point of the release agent for a certain period of time during cooling to allow crystal growth, or using two or more types of release agents with different melting temperatures. By this, crystal growth during cooling can be promoted and adjusted.

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

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

The toner according to 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.

<Electrostatic image developer>
The electrostatic image developer according to this embodiment contains at least the toner according to this embodiment. The electrostatic image developer according to the present embodiment may be a one-component developer containing only the toner according to the present embodiment, or may be a two-component developer containing a mixture of the toner and a carrier.

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

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

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

The surface of the core material can be coated with a resin by a method of coating with a coating layer forming solution in which a coating resin and various additives (used as necessary) are dissolved in an appropriate solvent. The solvent is not particularly limited and may be selected in consideration of the type of resin used, suitability for coating, etc. Specific resin coating methods include a dipping method in which the core material is immersed in a solution for forming a coating layer; a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material; and a method in which the core material is suspended in fluidized air. Examples include a fluidized bed method in which a coating layer forming solution is sprayed; a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater, and then the solvent is removed; and the like.

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

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

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

The image forming apparatus according to 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 including a developing means containing the electrostatic image developer according to the present embodiment is suitably used.

An example of an image forming apparatus according to the present embodiment will be described 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 type 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. to fourth image forming units 10Y, 10M, 10C, and 10K (image forming means). These image forming units (hereinafter also 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 are 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 that are in contact with the inner surface of the intermediate transfer belt 20, and runs in a direction from the first unit 10Y to the fourth unit 10K. There is. 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 belt cleaning device 30 is provided on the image holding surface side 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 the yellow image, are disposed on the upstream side in the traveling direction of the intermediate transfer belt. The first 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 (an example of primary transfer means) 5Y that transfers the toner image onto the intermediate transfer belt 20, and a photoreceptor cleaning device (an example of image carrier cleaning means) that removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer. Example) 6Y 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 photosensitive layer on a conductive substrate (for example, a volume resistivity of 1×10 ⁻⁶ Ωcm or less at 20° C.). This photosensitive layer normally has a high resistance (the resistance of a general resin), but when it is irradiated with a laser beam, it has a property that the specific resistance of the portion irradiated with the laser beam changes. Therefore, the surface of the charged photoreceptor 1Y is irradiated with a laser beam 3Y from the exposure device 3 according to image data for yellow sent from a control section (not shown). As a result, an electrostatic charge image of a yellow image pattern is formed on the surface of the photoreceptor 1Y.

An electrostatic charge image is an image formed on the surface of the photoconductor 1Y by electrical charging, and the laser beam 3Y reduces the specific resistance of the irradiated part 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 development 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 run 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 photoreceptor 1Y is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y acts on the toner image. The toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the toner polarity (-), and is controlled to, for example, +10 μA by a control section (not shown) in the first unit 10Y. The toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

The primary transfer biases applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M are 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 on which toner images of four colors are 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, causing 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.

The recording paper P on which the toner image has been transferred is fed into the pressure contact part (nip part) of a pair of fixing rolls in the fixing device (an example of a fixing means) 28, the toner image is fixed onto the recording paper P, and the fixed image is It is formed. 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.

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.

<Process cartridge, toner cartridge>
The process cartridge according to the present embodiment contains the electrostatic charge image developer according to the present embodiment, and is a developing means for developing the electrostatic charge image formed on the surface of the image 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 includes a developing means and, if necessary, at least one other means selected from an image carrier, a charging means, an electrostatic image forming means, a transfer means, etc. It may be a configuration.

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 an example of a 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.

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

The image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K are attached and detached, and developing devices 4Y, 4M, 4C, and 4K have toner cartridges corresponding to each color. The toner supply pipe is connected to the toner supply pipe (not shown). When the amount of toner contained in the toner cartridge becomes low, the toner cartridge is replaced.

Examples of the present invention will be described below, but the present invention is not limited to the following examples. In the following description, all "parts" and "%" are based on mass unless otherwise specified.
Further, the surface property index value, measured specific surface area value, calculated specific surface area value, specific gravity of the toner, and melting temperature Tm of the release agent were measured or calculated by the methods described above.

(Example 1)
-Preparation of cyan colored particle dispersion-
・C. I. Pigment Blue 15:3:50 parts, anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts, ion exchange water: 220 parts. ) at 240 MPa for 10 minutes to prepare a cyan colored particle dispersion (solid content concentration: 20%).

-Preparation of release agent particle dispersion (1) (wax1)-
・Ester wax (WEP-2 manufactured by NOF Corporation): 100 parts ・Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 2.5 parts ・Ion exchange water: 250 parts Above materials were mixed and heated to 120°C, dispersed using a homogenizer (Ultra Turrax T50 manufactured by IKA), and then subjected to dispersion treatment using a Manton-Gorlin high-pressure homogenizer (manufactured by Gorlin) to obtain a mold release agent with a volume average particle diameter of 330 nm. A release agent particle dispersion liquid (1) (wax 1, solid content 29.1%) in which particles were dispersed was obtained.

-Preparation of release agent particle dispersion (2) (wax2)-
・Fischer-Tropsch wax (HNP-9 manufactured by Nippon Seirin Co., Ltd.): 100 parts ・Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 2.5 parts ・Ion exchange water: 250 parts The above materials were mixed and heated to 120°C, dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA), and then subjected to dispersion treatment using a Manton-Gorlin high-pressure homogenizer (manufactured by Gorlin), resulting in a separation of particles with a volume average particle size of 340 nm. A mold release agent particle dispersion (2) (wax 2, solid content 29.2%) in which mold agent particles were dispersed was obtained.

-Preparation of release agent particle dispersion (3) (wax3)-
・Paraffin wax (Nippon Seirin Co., Ltd., FNP0090): 100 parts ・Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 2.5 parts ・Ion exchange water: 250 parts After mixing and heating to 120°C and dispersing using a homogenizer (Ultra Turrax T50 manufactured by IKA), dispersion treatment was performed using a Manton-Gorlin high-pressure homogenizer (manufactured by Gorlin) to form release agent particles with a volume average particle diameter of 360 nm. A release agent particle dispersion (3) (wax 3, solid content 29.0%) in which was dispersed was obtained.

-Preparation of release agent particle dispersion (4) (wax4)-
・Polyethylene wax (Polywax 725 manufactured by Toyo Petrolite Co., Ltd.): 100 parts ・Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 2.5 parts ・Ion exchange water: 250 parts Above The 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 Manton-Gorlin high-pressure homogenizer (manufactured by Gorlin) to form a mold with a volume average particle size of 370 nm. A release agent particle dispersion liquid (4) (wax 4, solid content 29.3%) in which agent particles were dispersed was obtained.

-Preparation of styrene acrylic resin dispersion-
・Styrene: 308 parts ・n-butyl acrylate: 100 parts ・acrylic acid: 2 parts ・β-carboxyethyl acrylate: 2 parts ・hexanethiol: 3 parts ・propanediol diacrylate: 1.5 parts Mix the above components, The dissolved mixture was added to an aqueous solution of 4 parts of an anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) dissolved in 550 parts of ion-exchanged water, emulsified in a flask, and then mixed for 10 minutes. Meanwhile, an aqueous solution of 6 parts of ammonium persulfate dissolved in 350 parts of ion-exchanged water was added to the flask, and after the nitrogen was replaced, the flask was heated in an oil bath while stirring until the contents reached 75°C. Emulsion polymerization was continued for the same time. In this way, a styrene acrylic resin dispersion (resin particle concentration: 42%) was obtained, in which resin particles having an average particle diameter of 220 nm and a weight average molecular weight (Mw) of 40,500 were dispersed. Note that the glass transition temperature of the amorphous styrene acrylic resin was 52°C.

-Preparation of cyan toner particles-
- Ion exchange water: 400 parts - Styrene acrylic resin particle dispersion: 200 parts - Cyan colorant particle dispersion: 40 parts - Release agent particle dispersion (2): 12 parts - Release agent particle dispersion (3) : 24 parts The above mixed components were put into a stirring tank, thoroughly mixed and dispersed with a homogenizer, and then 2.1 parts of a flocculant (polyaluminum chloride manufactured by Asada Chemical Industry Co., Ltd.) and 100 parts of ion-exchanged water were added. The mixture was added over 10 minutes while stirring the stirring tank at 300 rpm (rotations/min), and after the addition was completed, the mixture was heated to 49° C. at 1° C./min. After holding at 49° C. for 40 minutes, the particle size was measured using Coulter Multisizer II (manufactured by Beckman Coulter), and it was confirmed that aggregated particles with a volume average particle size of 4.8 μm had been formed.
To the dispersion containing aggregated particles prepared as described above, 115 parts of the resin particle dispersion was slowly added, and the temperature of the heating jacket was further raised and maintained at 50° C. for 1 hour. The volume average particle diameter of the obtained adhered particles was measured to be 5.7 μm.
Next, 1 mol/L aqueous sodium hydroxide solution was added so that the pH was 5.5, and then the anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd. 0.5 part of Neogen RK (manufactured by ) was added and held for 60 minutes. Thereafter, it was heated to 91° C. and held for 5 hours to coalesce. Thereafter, the obtained toner slurry was cooled to 85° C. and held for 1 hour. Thereafter, the slurry was cooled to 25° C., and the slurry was sieved through a 30 μm mesh to obtain cyan toner particles.

-Preparation of toner for electrostatic image development-
Cyan toner particles: 100 parts Silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name RY50): 0.8 parts The above composition was mixed with a Henschel mixer at a circumferential speed of 20 m/s for 15 minutes, and the toner of Example 1 ( A toner for developing electrostatic images was obtained.

-Preparation of carrier-
Styrene methyl methacrylate copolymer: 5 parts (mass ratio (styrene/methyl methacrylate): 70/30)
Toluene: 15 parts Carbon black (manufactured by Cabot, Regal 330): 1 part The above components were mixed and stirred with a stirrer for 10 minutes to prepare a solution for forming a coating layer. Next, this coating liquid and 100 parts of ferrite particles (volume average particle size: 40 μm) were placed in a vacuum degassing type kneader, stirred at 60°C for 30 minutes, and then degassed by reducing the pressure while heating. A carrier was prepared by drying.

-Preparation of electrostatic image developer-
8 parts of the toner of Example 1 and 92 parts of carrier were mixed in a V blender to prepare a developer (electrostatic image developer) of Example 1. In addition, each developer was obtained by changing the toner of Example 1 to each of the toners produced in the above toner production process.

(Examples 2 to 29 and Comparative Examples 1 and 2)
Example 1 except that the type and amount of release agent dispersion, amount of polyaluminum chloride, adjusted pH, coalescence temperature, cooling temperature after coalescence, and holding time were changed as shown in Table 1 below. In the same manner as above, toners and developers of Examples 2 to 29 and Comparative Examples 1 and 2 were prepared, respectively.

<Evaluation>
The obtained electrostatic image developer was filled into a developing device of a commercially available electrophotographic copying machine (Docu Center Color 450, manufactured by Fuji Xerox Co., Ltd.), and a PREMIER 80 A4 WHITE PAPEER (manufactured by Xerox Co., Ltd., basis weight 80 g/m ² ) After outputting 10,000 images with an area coverage of 5%, the Imaging Society of Japan Test Chart No. 5-2 was output, and the image defect evaluation (white spot degree evaluation) of the high TMA portion (tertiary color) and the difference in gloss between the roll portion and the non-roll portion were evaluated. Gloss was measured at 60° Gloss three times using a Gloss meter (micro-TRI-Gloss: Gardner), and the average value was calculated. The evaluation criteria are shown below.

- Evaluation of degree of whiteout (evaluation of image defects in high TMA areas (tertiary colors)) -
A: No white spots were observed either visually or by magnifying glass.
B: White voids cannot be visually confirmed, but slight voids were observed when observed with a magnifying glass.
C: Very slight white spots were visually observed.
D: White spots were observed. unacceptable level.

- Gloss unevenness evaluation (Gloss difference evaluation between roll part and non-roll part) -
A: Gloss difference is less than 5.
B: Gloss difference is 5 or more and less than 10.
C: Gloss difference is 10 or more and less than 15.
D: Gloss difference is 15 or more.
The smaller the Gloss difference, the less uneven gloss. In addition, A, B, and C are at levels that pose no practical problems.

The surface property index in Table 2 is the surface property index value expressed by the above formula S of the toner, and the aspect ratio number ratio of the release agent is the number of release agents having an aspect ratio of 5 or more in the toner. , is the value of a/b when the number of particles below 5 is b, and the aspect ratio area ratio of the release agent is the area where the aspect ratio of the release agent is 5 or more in the toner cross section is c, and the value of a/b is below 5. The melt viscosity of the toner is the value of c/d when the area of is d, and the melt viscosity of the toner is the melt viscosity of the toner measured by a flow tester method at a load of 10 kgf/cm ² . In addition, these were measured by the method mentioned above.
Further, "-" in the evaluation results in Table 2 indicates that the results are slightly inferior to the evaluation criteria listed.

From the results shown in Table 2 above, the toner for developing an electrostatic image of this example suppresses the occurrence of white spots in the obtained image and the uneven gloss of the obtained image, compared to the toner for developing an electrostatic image of the comparative example. I understand that.

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 Photoreceptor cleaning device (an example of image carrier 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 belt cleaning device (an example of intermediate transfer member cleaning means)
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 image carrier 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 (11)

Contains binder resin and mold release agent,
The melting temperature of the mold release agent is 65°C or more and 100°C or less,
The content of the release agent is 1% by mass or more and 20% by mass or less based on the entire toner particles,
When the number of release agents in the toner with an aspect ratio of 5 or more is a, and the number of release agents below 5 is b, 1.0<a/b<8.0,
A toner for developing an electrostatic image, which has a surface property index value expressed by the following formula S of 2.0 or more and 2.8 or less.
(Surface property index value) = (Actual measured value of specific surface area) / (Calculated value of specific surface area) Formula S
(Specific surface area calculation value) = (sum of surface areas calculated from circle-equivalent diameters of 4500 toner particles in flow particle image analysis)/{(specific gravity of toner) Sum of volumes calculated from circle equivalent diameter)} The toner for developing an electrostatic image according to claim 1, wherein the binder resin contains a styrene acrylic resin. The toner for developing an electrostatic image according to claim 1 or 2, which contains a metal element. The toner for developing an electrostatic image according to claim 3, wherein the metal element is at least one selected from the group consisting of aluminum, calcium, barium, and magnesium. The toner for developing an electrostatic image according to any one of claims 1 to 4, wherein the content of aluminum atoms determined by fluorescent X-ray analysis is 0.005 kcps or more and 0.35 kcps or less. The toner for developing an electrostatic image according to any one of claims 1 to 5, wherein the releasing agent has a melting temperature of 75°C or more and 100°C or less. An electrostatic image developer comprising the electrostatic image developing toner according to any one of claims 1 to 6 . A toner cartridge containing the toner for developing an electrostatic image according to any one of claims 1 to 6 , and being detachable from an image forming apparatus. An image forming apparatus comprising: a developing means containing the electrostatic image developer according to claim 7 , and developing an electrostatic image formed on the surface of an image carrier as a toner image by the electrostatic image developer. A process cartridge that can be installed and removed. an image holder;
Charging means for charging the surface of the image carrier;
an electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means containing the electrostatic image developer according to claim 7 , and developing an electrostatic image formed on the surface of the image carrier as a toner image by the electrostatic image developer;
a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
a fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising: a charging step of charging the surface of the image carrier;
an electrostatic 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 claim 7 ;
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: