JP6217480B2 - Non-magnetic one-component developer, process cartridge, image forming apparatus, and image forming method - Google Patents

Description

  The present invention relates to a non-magnetic one-component developer, a process cartridge, an image forming apparatus, and an image forming method.

  A method for visualizing image information through an electrostatic charge image by electrophotography or the like is currently used in various fields. In electrophotography, image information is formed as an electrostatic charge image on the surface of an image carrier (photoreceptor) by charging and exposure processes, and a toner image is developed on the surface of the photoreceptor using a developer containing toner. The toner image is visualized as an image through a transfer process for transferring the toner image to a recording medium such as paper and a fixing process for fixing the toner image on the surface of the recording medium.

For example, Patent Document 1 states that “the volume average particle diameter is 3 to 7 μm, the average circularity is 0.960 to 0.995, the standard deviation of the circularity is 0.040 or less, and the surface properties. Is a toner for non-magnetic one-component development, in which 0.001 to 0.1% by weight of a fatty acid metal salt having a volume average particle diameter of 1.5 to 12 μm is externally added to toner particles satisfying a specific conditional expression. Image forming method ".
Patent Document 2 states that “the degree of circularity is 0.970 or more, the spherical toner core surface has irregularities, the convex parts are granular, and the average particle diameter is 100 nm to 500 nm. An electrostatic charge image developing toner characterized by being integrated at a coverage of 10% to 80% is disclosed.
Patent Document 3 states that “the average valley depth Rvm of toner particles containing inorganic fine particles having a number average particle diameter of 80 nm to 150 nm and measured with a scanning probe microscope is 120 nm to 200 nm, and the unevenness average in the X direction is A toner whose interval W satisfies 0.15 <Rvm / W <1.0 is disclosed.

JP 2004-163807 A JP 2008-233430 A JP 2007-279400 A

  An object of the present invention is to provide a non-magnetic one-component developer that suppresses generation of color streaks and color points.

  The above problem is solved by the following means.

The invention according to claim 1
Toner particles having one or more depressions having a depth of 0.2 μm or more on the surface and containing 52 number% or more of all toner particles, and the average circularity of all toner particles being 0.970 or more,
At least one external additive selected from the group consisting of external additive A composed of silica particles having a number average particle diameter of 5 nm to 60 nm, and fatty acid metal salt particles, molybdenum disulfide particles, tungsten disulfide particles, and boron nitride particles. An external additive containing Agent B,
A non-magnetic one-component developer.

The invention according to claim 2
A developing means for accommodating the non-magnetic one-component developer according to claim 1 and developing the electrostatic image formed on the surface of the image carrier as a toner image by the non-magnetic one-component developer,
A process cartridge attached to and detached from the image forming apparatus.

The invention according to claim 3
An 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;
A developing unit that contains the non-magnetic one-component developer according to claim 1 and that develops an electrostatic image formed on the surface of the image carrier as a toner image by the non-magnetic one-component developer;
Transfer means for transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising:

The invention according to claim 4
A charging step for 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, as a toner image, an electrostatic image formed on the surface of the image carrier with the nonmagnetic one-component developer according to claim 1;
A transfer step of transferring a 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 first aspect of the present invention, there is provided a non-magnetic one-component developer that suppresses the generation of color streaks and color points as compared with the case where only one of the external additive A and the external additive B is externally added. Is done.

  According to the invention according to claim 2, 3 or 4, color streak and color are compared with the case of applying a non-magnetic one-component developer to which only one of external additive A and external additive B is externally added. A process cartridge, an image forming apparatus, or an image forming method that suppresses occurrence of dots is provided.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows an example of the process cartridge which concerns on this embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described in detail.

<Non-magnetic one-component developer>
The nonmagnetic one-component developer according to this embodiment includes toner particles and an external additive.
The toner particles contain 50% by number or more of toner particles A having one or more depressions having a depth of 0.2 μm or more on the surface, and the average circularity of all toner particles is 0.970 or more.
The external additive is selected from the group consisting of external additive A composed of silica particles having a number average particle diameter of 5 nm to 60 nm, and fatty acid metal salt particles, molybdenum disulfide particles, tungsten disulfide particles, and boron nitride particles. And at least one external additive B selected.
Hereinafter, the non-magnetic one-component developer may be referred to as “electrostatic image developer”, “developer”, or “toner”.

  Here, in the non-magnetic one-component development system, a toner layer regulating member (for example, a layer) that supplies toner to a toner holder (for example, a development roll) by a toner supply member (for example, a toner supply roll) and contacts the toner holder. The toner layer is formed by a regulating blade), the thickness of the toner layer is regulated, and the toner is charged. Then, the toner charged by the toner holding member is supplied to an image holding member (for example, an electrophotographic photosensitive member), and the electrostatic latent image on the image holding member is developed with the toner.

  In this non-magnetic one-component development system, the toner supply member and the toner holder are arranged in contact with each other. Therefore, the toner is subjected to a mechanical load at the contact portion between the toner supply member and the toner holder.

  While the toner is constantly flowing during the image formation, when the image formation is completed with the temperature inside the image forming apparatus being raised by the image forming operation, the toner present at the contact portion between the toner supply member and the toner holder is However, it is difficult to exchange without flowing, and continues to receive a load due to heat and pressure. If the toner continues to receive a load due to heat and pressure, the toner particles may be fused. When the toner in this state is developed, it is considered that color streaks and color points are generated as image quality defects. In particular, in a high-temperature and high-humidity environment (for example, in an environment of a temperature of 30 ° C. and a humidity of 70% RH), the temperature in the image forming apparatus tends to increase due to continuous image formation, and color streaks and color points are likely to occur. It is considered to be.

On the other hand, in the developer according to this embodiment, the occurrence of color streaks and color points is suppressed by the above configuration.
The reason for this is not clear, but is presumed to be as follows.

First, the toner particles A having an average circularity of 0.970 or more and one or more depressions having a depth of 0.2 μm or more on the surface are maintained in a shape close to a sphere, and an external additive comprising silica particles described later. It is a granular material having a depression having a depth larger than the particle size of A on the surface. The toner particles containing 50% by number or more of the toner particles A have a nearly spherical shape, and therefore, the probability that the other toner particles A, or the toner supply member and the toner holder are in contact with the bottom of the recess is small. It is considered to be.
Therefore, when the external additive A composed of silica particles having a small number average particle diameter of 5 nm or more and 60 nm or less is externally added to the toner particles including the toner particles A having this property, the external additive A is formed in the depressions of the toner particles A. It becomes easy to adhere. The external additive A adhering to the dent of the toner particle A is not easily subjected to a mechanical load and is likely to be present in the dent without being embedded in the toner particle A. When all of the toner particles have an irregular shape with an average circularity of less than 0.970, sharp protrusions are likely to be present on the surface of the toner particles A, and the protrusions come into contact with the bottoms of other toner particle A recesses. The probability is increased, and embedding of the external additive A attached to the depression is facilitated.

Further, the toner particles A having this property are added with an external additive A and at least one external additive B selected from the group consisting of fatty acid metal salt particles, molybdenum disulfide particles, tungsten disulfide particles, and boron nitride particles. When added, the external additive A and the external additive B that are present without being embedded in the depressions of the toner particles A form a mixed powder by stirring in the developing device, and the toner supply member and the toner holder are brought into contact with each other. To be supplied to the part. At this time, it is considered that the mixed powder supplied to the contact portion does not become a compacted state due to the pressure between the members but accumulates in the contact portion. This is considered to be due to the lubricating action of the particles as the external additive B.
The mixed powder that is not in the compacted state intervenes between the toner particles, so that even if the toner continues to receive a load due to heat and pressure at the contact portion between the toner supply member and the toner holder. In addition, fusion between toner particles is difficult to occur.

  For the above reasons, it is estimated that the developer according to the present embodiment suppresses the generation of color streaks and color points.

  Hereinafter, the developer according to the exemplary embodiment will be described in detail.

(Toner particles)
The toner particles include toner particles A having one or more depressions having a depth of 0.2 μm or more on the surface. The toner particles have an average circularity of all particles of 0.970 or more.

  The toner particles A are contained in an amount of 50% by number or more with respect to all the toner particles. From the viewpoint of suppressing the fusion of the toner particles, the ratio of the toner particles A is preferably 60% or more and more preferably 70% by number or more based on the total toner particles. However, the ratio of the toner particles A is most preferably 100% by number with respect to all the toner particles, but is preferably 98% by number or less and more preferably 95% by number or less from the viewpoint of powder flowability.

  The depth of one or more recesses on the surface of the toner particles A is 0.2 μm or more, but is preferably 0.25 μm or more, more preferably 0.3 μm or more from the viewpoint of further suppressing the fusion between the toner particles. preferable. However, the depth of the depression of the toner particles A is preferably 1.0 μm or less, and more preferably 0.8 μm or less from the viewpoint of securing the strength of the toner particles A. When the depth of the depression of the toner particles A is 0.2 μm or more, the toner particles are prevented from coming into direct contact with the external additive A (silica particles) adhering to the depression, and the embedding of the external additive A is suppressed. The As a result, fusion of toner particles is suppressed.

  The size (diameter) of the recesses having a depth of 0.2 μm or more of the toner particles A is preferably 0.15 μm or more and 1.0 μm or less, more preferably 0.2 μm or more and 0.2 μm or less, from the viewpoint of further suppressing fusion of the toner particles. 9 μm or less is more preferable, and 0.25 μm or more and 0.8 μm or less is still more preferable. When the size of the dent having a depth of 0.2 μm or more of the toner particles A is in the above range, the external additive A (silica particles) easily adheres to the dent while maintaining the shape of the toner particle A close to a sphere. As a result, fusion of toner particles is suppressed.

  The number of depressions having a depth of 0.2 μm or more in the toner particles A is one or more, but the probability that the external additive A (silica particles) adheres to the depressions is increased, and the fusion between the toner particles is further suppressed. From the point, 1 or more and 10 or less are preferable, and 1 or more and 8 or less are more preferable.

Here, the ratio of the toner particles A is a value measured by the following method.
First, after a toner (developer) to be measured is dispersed in water containing a surfactant, ultrasonic treatment is performed to obtain toner particles from which the external additive has been removed.
Next, a 3D image of the obtained toner particles is obtained at a magnification of 10,000 with an electron beam three-dimensional roughness analyzer (Elionix, ERA8900FE). In the obtained 3D image, a height profile of the outer edge of the toner particles is obtained. In this height profile, if there is a height difference of 0.2 μm or more with respect to the reference height, it is determined that a depression having a depth of 0.2 μm or more exists on the surface of the toner particles. However, the reference height is determined by performing shape correction using a spline filter, canceling the influence of the edge, and performing tilt correction.
The same operation is performed on 100 toner particles, and the ratio of toner particles A having one or more depressions having a depth of 0.2 μm or more on the surface is obtained. The observation of the toner dent is only the observation of one side of the toner. This numerical value is defined as the ratio of the toner particles A having a dent having a depth of 0.2 μm or more on the surface.

  In addition, the depth of the depressions having one or more toner particles A is the difference between the bottom peak and the reference height in a region having a height difference of 0.2 μm or more with respect to the reference height in the obtained height profile. It is defined as Then, the value of the depth of the depression having one or more toner particles A is the average value of the values obtained by examining 100 toner particles A. In the case where there are a plurality of regions having a difference in height in one toner particle A, the average value including the depth of the depression of 0.2 μm or more of the obtained toner particle A is used.

  In addition, the size of the depression of the toner particle A having a depth of 0.2 μm or more is defined as the length of a region having a height difference of 0.2 μm or more with respect to the reference height in the obtained height profile. Then, the value of the size of the recess having a depth of 0.2 μm or more of the toner particles A is an average value of values obtained by checking 100 toner particles A. When there are a plurality of regions having a difference in height in one toner particle A, the average value including the size of the recesses of the obtained toner particle A having a depth of 0.2 μm or more is used.

  Further, the number of depressions having a depth of 0.2 μm or more of the toner particles A is defined as the number of regions having a height difference of 0.2 μm or more with respect to the reference height in the obtained height profile. Then, the value of the number of depressions having a depth of 0.2 μm or more of the toner particles A is an average value of values obtained by examining 100 toner particles A.

  As a method for obtaining toner particles containing 50% by number or more of toner particles A with respect to all toner particles, for example, in an emulsion aggregation method, two or more kinds of binder resin particles having different glass transition temperatures are used (specifically, For example, two or more kinds of binder resin particles having different glass transition temperatures are used as the binder resin for the toner particle coating layer (shell layer)), the temperature or time at which the aggregated particles are fused and united, etc. The method of adjusting etc. are mentioned.

  In the toner particles, the toner particles B other than the toner particles A are not particularly limited as long as the surface does not have a recess having a depth of 0.2 μm or more, but from the viewpoint of suppressing the fusion of the toner particles, The average circularity of the toner particles may be adjusted to 0.970 or more (preferably 0.975 or more, more preferably 0.978 or more).

  The average circularity of all the toner particles is 0.970 or more, but 0.975 or more is preferable and 0.978 or more is more preferable from the viewpoint of further suppressing the fusion of the toner particles. However, the average circularity of all the toner particles is most preferably 1.0, but is preferably 0.995 or less, and more preferably 0.993 or less, from the viewpoint of cleaning the residual toner. When the average circularity of all the toner particles is 0.970 or more, the shape of the toner particles approaches a spherical shape, the contact probability of other toner particles at the bottom of the toner particle depression becomes small, and the external additive A attached to the depression. The embedding of (silica particles) is suppressed. As a result, fusion of toner particles is suppressed.

The average circularity of all toner particles is obtained by (circle equivalent circumference) / (perimeter) [(perimeter of a circle having the same projection area as the particle image) / (perimeter of the projected particle image)]. Specifically, it is a value measured by the following method.
First, after a toner (developer) to be measured is dispersed in water containing a surfactant, ultrasonic treatment is performed to obtain toner particles from which the external additive has been removed.
The obtained toner particles are collected by suction, a flat flow is formed, a flash image is instantaneously emitted, a particle image is captured as a still image, and the particle image is analyzed by a flow type particle image analyzer (manufactured by Sysmex Corporation). FPIA-2100). The number of samplings for obtaining the average circularity is 3500.

Hereinafter, the components of the toner particles will be described.
In the toner particles, both the toner particles A and the toner particles B contain a binder resin. The toner particles A and the toner particles B may contain a colorant, a release agent, and other additives as necessary.

-Binder resin-
Examples of the binder resin include styrenes (eg, styrene, parachlorostyrene, α-methylstyrene, etc.), (meth) acrylic acid esters (eg, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic acid). n-butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (for example, acrylonitrile, Methacrylonitrile, etc.), vinyl ethers (eg, vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (eg, ethylene, propylene, etc.) Emissions, a homopolymer of a monomer such as butadiene) and the like, or a vinyl-based resin composed of these monomers with two or more combinations copolymer.
As the binder resin, for example, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, non-vinyl resin such as modified rosin, a mixture of these with the vinyl resin, or these Examples also include a graft polymer obtained by polymerizing a vinyl monomer in the coexistence.
These binder resins may be used alone or in combination of two or more.

A polyester resin is suitable as the binder resin.
Examples of the polyester resin include known polyester resins.

  As a polyester resin, the condensation polymer of polyhydric carboxylic acid and polyhydric alcohol is mentioned, for example. In addition, as a polyester resin, a commercial item may be used and what was synthesize | combined may be used.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (eg, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.) Alicyclic dicarboxylic acids (for example, cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (for example, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or lower (for example, having 1 or more carbon atoms) 5 or less) alkyl esters. Among these, as polyvalent carboxylic acid, aromatic dicarboxylic acid is preferable, for example.
The polyvalent carboxylic acid may be used in combination with a dicarboxylic acid or a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, having 1 to 5 carbon atoms) alkyl esters.
Polyvalent carboxylic acid may be used individually by 1 type, and may use 2 or more types together.

Examples of the polyhydric alcohol include aliphatic diols (for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (for example, cyclohexanediol, cyclohexanedimethanol, Hydrogenated bisphenol A, etc.) and aromatic diols (for example, ethylene oxide adducts of bisphenol A, propylene oxide adducts 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 trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used together with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
A polyhydric alcohol may be used individually by 1 type, and may use 2 or more types together.

The glass transition temperature (Tg) of the polyester resin is preferably 50 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 65 ° C. or lower.
The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, described in the method for determining the glass transition temperature in JIS K-1987 “Method for Measuring Transition Temperature of Plastics”. It is determined by “extrapolated glass transition start temperature”.

The weight average molecular weight (Mw) of the polyester resin is preferably from 5,000 to 200,000, more preferably from 7000 to 150,000.
The number average molecular weight (Mn) of the polyester resin is preferably 2000 or more and 50,000 or less.
The molecular weight distribution Mw / Mn of the polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.
The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed with a THF solvent using a Tosoh GPC / HLC-8120GPC as a measuring device and a Tosoh column / TSKgel SuperHM-M (15 cm). The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample from this measurement result.

The polyester resin is obtained by a well-known manufacturing method. Specifically, for example, the polymerization temperature is set to 180 ° C. or higher and 230 ° C. or lower, the pressure in the reaction system is reduced as necessary, and the reaction is performed while removing water and alcohol generated during the condensation.
In addition, when the monomer of the raw material is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added and dissolved as a solubilizing agent. In this case, the polycondensation reaction is performed while distilling off the solubilizer. If a monomer with poor compatibility is present in the copolymerization reaction, the monomer with poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance and then polymerized together with the main component. It is good to condense.

  The content of the binder resin is, for example, preferably 40% by mass to 99% by mass, more preferably 50% by mass to 97% by mass, and more preferably 60% by mass to 95% by mass with respect to the entire toner particles. Further preferred.

-Colorant-
Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, brilliant. Carmine 6B, Dupont Oil Red, Pyrazolone Red, Resol 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, or acridine series, xanthene series, azo series Various dyes such as benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, and thiazole Can be mentioned.
A colorant may be used individually by 1 type and may use 2 or more types together.

  As the colorant, a surface-treated colorant may be used as necessary, or it may be used in combination with a dispersant. 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, and more preferably 3% by mass or more and 15% by mass or less with respect to the entire toner particles.

-Release agent-
Examples of 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. And so on. The release agent is not limited to this.

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

  The content of the release agent is, for example, preferably 1% by mass to 20% by mass and more preferably 2% by mass to 15% by mass with respect to the entire toner particles.

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

-Toner particle characteristics-
The toner particles may be toner particles having a single layer structure, or toner particles having a so-called core / shell structure composed of a core (core particle) and a coating layer (shell layer) covering the core. May be.
Here, the core / shell structure toner particles include, for example, a core portion including a binder resin and, if necessary, other additives such as a colorant and a release agent, and a binder resin. It is good to be comprised with the comprised coating layer.

  The volume average particle diameter (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 3 μm or more and 8 μm or less.

The various average particle diameters and various particle size distribution indexes of the toner particles are measured using Coulter Multisizer II (manufactured by Beckman-Coulter), and the electrolyte is measured using ISOTON-II (manufactured by Beckman-Coulter). The
In the measurement, 0.5 mg to 50 mg of a measurement sample is added as a dispersant to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate). This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolyte in which the sample is suspended is dispersed for 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a particle size in the range of 2 μm to 60 μm is measured using a 100 μm aperture with a Coulter Multisizer II. taking measurement. The number of particles to be sampled is 50,000.
For the particle size range (channel) divided based on the measured particle size distribution, draw the cumulative distribution from the smaller diameter side for the volume and number, respectively, and the particle size to be 50% is the volume average particle size D50v, the cumulative number The average particle diameter is defined as D50p.

(External additive)
The external additive is at least selected from the group consisting of external additive A composed of silica particles having a number average particle diameter of 5 nm to 60 nm, and fatty acid metal salt particles, molybdenum disulfide particles, tungsten disulfide particles, and boron nitride particles. A kind of external additive B.

  In the external additive A, examples of the silica particles include well-known silica particles such as fumed silica particles, sol-gel silica particles, and colloidal silica particles. Among these, from the viewpoint of suppressing fusion between toner particles. Fumed silica particles are preferred.

  The number average particle diameter of the silica particles is 5 nm or more and 60 nm or less, but is preferably 5 nm or more and 55 nm or less, and more preferably 7 nm or more and 50 nm or less from the viewpoint of further suppressing the fusion of the toner particles. When the number average particle diameter of the silica particles is 5 nm or more, embedding in the toner particles A is suppressed. When the number average particle diameter of the silica particles is 60 nm or less, the adhesion of the external additive B to the silica particles is enhanced. As a result, fusion of toner particles is suppressed.

The silica particles are preferably hydrophobized. The hydrophobic treatment is performed, for example, by immersing inorganic particles in a hydrophobic treatment agent. Examples of the hydrophobizing agent include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents, and the like. Among these, as the hydrophobizing agent, a silane coupling agent (for example, dimethyldichlorosilane, dimethyldimethoxysilane, hexamethyldisilazane, methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, etc.) is preferable. . These hydrophobizing agents may be used alone or in combination of two or more.
The amount of the hydrophobizing agent is usually 1 part by mass or more and 30 parts by mass with respect to 100 parts by mass of silica particles, for example.

  The amount of external additive A (silica particles) added is preferably 0.1 parts by mass or more and 5 parts by mass or less, more preferably 0.2 parts by mass or more and 4 parts by mass or less, with respect to 100 parts by mass of the toner particles. More preferred is 0.3 part by mass or more and 3 parts by mass or less.

In the external additive B, the fatty acid metal salt particles are salt particles composed of a fatty acid and a metal.
Examples of the fatty acid include fatty acids having 10 to 25 carbon atoms. Examples of the metal include magnesium, calcium, aluminum, barium, and zinc. Zinc is particularly preferable.

  Examples of the fatty acid metal salt particles include aluminum stearate, calcium stearate, potassium stearate, magnesium stearate, barium stearate, lithium stearate, zinc stearate, copper stearate, lead stearate, nickel stearate, stearic acid. Strontium, cobalt stearate, sodium stearate, zinc oleate, manganese oleate, iron oleate, aluminum oleate, copper oleate, magnesium oleate, calcium oleate, zinc palmitate, cobalt palmitate, copper palmitate, Magnesium palmitate, Aluminum palmitate, Calcium palmitate, Zinc laurate, Manganese laurate, Calcium laurate, Iron laurate, Lauri Magnesium acid, aluminum laurate, zinc linoleate, cobalt linoleate, calcium linoleate, zinc ricinoleate, and each particle, such as ricinoleic acid aluminum.

  Among these, as fatty acid metal salt particles, particles of zinc stearate, zinc laurate, and magnesium stearate are preferable, and zinc stearate particles are more preferable.

  The number average particle diameter of the external additive B is preferably 0.2 μm or more and 15 μm or less, more preferably 0.3 μm or more and 12 μm or less, and further preferably 0.4 μm or more and 10 μm or less from the viewpoint of suppressing fusion of toner particles. preferable.

  The external addition amount of the external additive B is preferably 0.05 parts by mass or more and 4 parts by mass or less, more preferably 0.1 parts by mass or more and 3 parts by mass or less, and 0.15 parts by mass with respect to 100 parts by mass of the toner particles. More preferred is at least 2.5 parts by weight.

  Here, the mass ratio of the external additive A and the external additive B (external additive A / external additive B) is preferably 0.2 or more and 10 or less from the viewpoint of suppressing the fusion of the toner particles. 0.3 or more and 8 or less are more preferable, and 0.4 or more and 6 or less are still more preferable.

The number average particle diameter of the external additive is a value measured by the following method.
First, the toner to be measured is observed with a scanning electron microscope (SEM). Then, the equivalent circle diameter of each of the 100 external additives to be measured is obtained by image analysis, and the circle equivalent diameter of 50% (50th) cumulative number from the small diameter side in the number-based distribution is the number average particle diameter. And
Image analysis for obtaining the equivalent circle diameter of 100 external additives to be measured is performed by taking a two-dimensional image with a magnification of 10,000 times using an analysis apparatus (ERA-8900: manufactured by Elionix), and image analysis software. Using WinROOF (manufactured by Mitani Shoji Co., Ltd.), the projected area is obtained under the condition of 0.010000 μm / pixel, and the equivalent circle diameter is obtained by the formula: equivalent circle diameter = 2√ (projected area / π).
In order to measure the number average particle diameter of each external additive from the toner, it is necessary to distinguish between external additive A and external additive B. This external additive A and external additive B perform element mapping by SEM-EDX, and Si element derived from external additive A and Mo, W, B, Mg, Ca, derived from external additive B, A distinction is made by associating elements such as Al, Ba and Zn with external additives.

As the external additive, other external additives other than the external additive A and the external additive B may be used in combination. However, the ratio of the external additive A and the external additive B to the total external additives is preferably 50% by mass or more (preferably 60% by mass or more).
Examples of other external additives include known external additives for inorganic particles and organic particles. Inorganic particles include alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, bengara And particles of antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, and the like. Examples of the organic particles include vinyl polymers such as styrene polymers, (meth) acrylic polymers, and ethylene polymers; various heavy polymers such as melamine polymers, amide polymers, and allyl phthalate polymers. Fluorine polymers such as polytetrafluoroethylene and polyvinylidene fluoride; higher alcohols; and the like.

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

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

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

Details of each step will be described below.
In the following description, a method of obtaining toner particles containing a colorant and a release agent will be described. However, the colorant and the release agent are used as necessary. Of course, you may use other additives other than a coloring agent and a mold release agent.

-Preparation step of resin particle dispersion-
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. To do.

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

Examples of the dispersion medium used for the resin particle dispersion include an aqueous medium.
Examples of the aqueous medium include water such as distilled water and ion exchange water, and alcohols. These may be used individually by 1 type and may use 2 or more types together.

Examples of the surfactant include anionic surfactants such as sulfate ester, sulfonate, phosphate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol And nonionic surfactants such as polyphenols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, an anionic surfactant and a cationic surfactant are particularly mentioned. The nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant.
Surfactant may be used individually by 1 type and may use 2 or more types together.

Examples of the method for dispersing the resin particles in the dispersion medium in the resin particle dispersion include a general dispersion method such as a rotary shear homogenizer, a ball mill having media, a sand mill, and a dyno mill. 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.
The phase inversion emulsification method is a method in which a resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, and a base is added to the organic continuous phase (O phase) to neutralize the aqueous medium. (W phase) is added to convert the resin from W / O to O / W (so-called phase inversion) to form a discontinuous phase and disperse the resin in an aqueous medium in the form of particles. It is.

The volume average particle size 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. .
In addition, the volume average particle diameter of the resin particles is based on the particle size range (channel) divided by using the particle size distribution obtained by measurement with a laser diffraction particle size distribution measuring apparatus (for example, LA-700 manufactured by Horiba, Ltd.). The cumulative distribution is subtracted from the small particle diameter side with respect to the volume, and the particle diameter that becomes 50% cumulative with respect to all particles is measured as the volume average particle diameter D50v. The volume average particle size of particles in other dispersions is also measured in the same manner.

  As content of the resin particle contained in a resin particle dispersion liquid, 5 to 50 mass% is preferable, for example, and 10 to 40 mass% is more preferable.

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

-Aggregated 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, resin particles, colorant particles, and release agent particles are hetero-aggregated to have resin particles, colorant particles, and release agent particles having a diameter close to the diameter of the target toner particles. Aggregated particles are formed.

Specifically, for example, the flocculant is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to acidic (for example, the pH is 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. The resin particles are heated to a glass transition temperature (specifically, for example, the glass transition temperature of the resin particles −30 ° C. or more and the glass transition temperature or less), and the particles dispersed in the mixed dispersion are aggregated to form aggregated particles. Form.
In the agglomerated particle forming step, for example, the aggregating agent is added at room temperature (for example, 25 ° C.) while stirring the mixed dispersion with a rotary shearing homogenizer, and the pH of the mixed dispersion is acidic (for example, the pH is 2 or more and 5 or less). ), And after adding a dispersion stabilizer as necessary, the heating may be performed.

  Examples of the flocculant include surfactants having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, for example, inorganic metal salts and divalent or higher-valent metal complexes. In particular, when a metal complex is used as the flocculant, the amount of the surfactant used is reduced, and the charging characteristics are improved.

  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 substances such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include metal salt polymers.

-Fusion / unification process-
Next, the agglomerated particle dispersion in which the agglomerated particles are dispersed is heated to, for example, a glass transition temperature or higher of the resin particles (for example, a temperature of 10 to 50 ° C. higher than the glass transition temperature of the resin particles). Are fused and united to form toner particles.

Through the above steps, toner particles are obtained.
In addition, after obtaining the aggregated particle dispersion liquid in which the aggregated particles are dispersed, the aggregated particle dispersion liquid and the resin particle dispersion liquid in which the resin particles are dispersed are further mixed, and the resin particles are further added to the surface of the aggregated particles. A process of aggregating to adhere to form second aggregated particles, and heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and coalesce the second aggregated particles. The toner particles may be manufactured through a step of forming toner particles having a core / shell structure.

Here, after completion of the fusion / unification process, toner particles formed in the solution are dried through a known washing process, solid-liquid separation process, and drying process to obtain toner particles.
In the washing step, it is preferable to sufficiently carry out substitution washing with ion-exchanged water from the viewpoint of chargeability. The solid-liquid separation step is not particularly limited, but suction filtration, pressure filtration, etc. are preferably performed from the viewpoint of productivity. Also, the drying process is not particularly limited, but from the viewpoint of productivity, freeze drying, flash jet drying, fluidized drying, vibration fluidized drying, or the like is preferably performed.

  The toner according to the exemplary embodiment is manufactured, for example, by adding an external additive to the obtained dry toner particles and mixing them. Mixing may be performed, for example, with a V blender, a Henschel mixer, a Ladyge mixer, or the like. Furthermore, if necessary, coarse toner particles may be removed using a vibration classifier, a wind classifier, or the like.

<Image Forming Apparatus / Image Forming Method>
The image forming apparatus / image forming method according to the present embodiment will be described.
The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the surface of the image carrier, an electrostatic image forming unit that forms an electrostatic image on the surface of the charged image carrier, and an electrostatic charge. Development means for containing an image developer and developing the electrostatic image formed on the surface of the image carrier as a toner image with the electrostatic image developer, and the toner image formed on the surface of the image carrier as a recording medium Transfer means for transferring to the surface of the recording medium, and fixing means for fixing the toner image transferred to the surface of the recording medium. The electrostatic charge image developer according to this embodiment is applied as the electrostatic charge image developer.

  In the image forming apparatus according to this embodiment, a charging process for charging the surface of the image carrier, an electrostatic charge image forming process for forming an electrostatic image on the surface of the charged image carrier, and an electrostatic charge according to this 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 to the surface of the recording medium; An image forming method (an image forming method according to the present embodiment) including a fixing step of fixing the toner image transferred onto the surface of the recording medium is performed.

  Here, in the image forming apparatus according to the present embodiment, a developing unit of a non-magnetic one-component developing system is applied as the developing unit. The developing means of the non-magnetic one-component development system includes, for example, a toner supply member (for example, a toner supply roller) and a stirring member that are adjacent to a toner holder (for example, a development roll) of non-magnetic one-component toner (non-magnetic one-component developer) (For example, an agitator) supplies toner to the surface of the toner holder, forms a toner layer with a toner layer regulating member (for example, a layer regulating blade), charges the toner, and then charges an image carrier (for example, an electrophotographic photoreceptor). The developing means of the type in which the toner is attached to the electrostatic charge image on the surface of (2) and developed. As the developing means of the non-magnetic one-component developing system, a known device may be employed.

The image forming apparatus according to the present embodiment is a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image carrier to a recording medium; the toner image formed on the surface of the image carrier is transferred to an intermediate transfer member An intermediate transfer type apparatus that primarily transfers the toner image transferred to the surface of the intermediate transfer body and then secondary transfer the toner image to the surface of the recording medium; after the toner image is transferred, the surface of the image carrier before charging is cleaned. An apparatus provided with a cleaning unit; a known image forming apparatus such as an apparatus provided with a charge removing unit that discharges the surface of an image holding member by irradiating a discharge light after charging a toner image and before charging is applied.
In the case of an intermediate transfer type apparatus, the transfer means includes, for example, an intermediate transfer body on which a toner image is transferred to the surface, and a primary transfer that primarily transfers the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body. And a secondary transfer unit that secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of the recording medium.

  In the image forming apparatus according to the present embodiment, for example, the part including the developing unit may have a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge that accommodates the electrostatic charge image developer according to this embodiment and includes a developing unit is preferably used.

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to the present embodiment.
The image forming apparatus shown in FIG. 1 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) are provided. 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. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the image forming apparatus.

  Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is provided by being 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 that are spaced apart from each other in the left to right direction in the drawing. The vehicle travels in the direction toward the unit 10K. The support roll 24 is applied with a force in a direction away from the drive roll 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around the support roll 24. An intermediate transfer member cleaning device 30 is provided on the side of the image carrier of the intermediate transfer belt 20 so as to face the drive roll 22.

  Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, here, the first unit that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. 10Y will be described as a representative. It should be noted that reference numerals with magenta (M), cyan (C), and black (K) are attached to the same parts as those of the first unit 10Y instead of yellow (Y). Description of the units 10M, 10C, and 10K will be omitted.

The first unit 10Y includes a photoreceptor 1Y that functions as an image holding member. Around the photoreceptor 1Y, a charging roll (an example of a charging unit) 2Y for charging the surface of the photoreceptor 1Y to a predetermined potential, and the charged surface is exposed by a laser beam 3Y based on a color-separated image signal. Then, an exposure device (an example of an electrostatic image forming unit) 3 that forms an electrostatic image, and a developing device (an example of a developing unit) 4Y that develops the electrostatic image by supplying toner charged to the electrostatic image, developed A primary transfer roll 5Y (an example of a primary transfer unit) that transfers a toner image onto the intermediate transfer belt 20, and a photoconductor cleaning device (an example of a cleaning unit) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer. Are arranged in order.
The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described.
First, prior to the operation, the surface of the photoreceptor 1Y is charged by the charging roll 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate. This photosensitive layer is usually high resistance (general resin resistance), but has the property that when the laser beam (or LED light) 3Y is irradiated, the specific resistance of the portion irradiated with the laser beam changes. ing. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic charge image having a yellow image pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, and the charged charge on the surface of the photoreceptor 1Y flows. On the other hand, this is a so-called negative latent image formed by the charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic charge image on the photoreceptor 1Y is visualized (developed image) as a toner image by the developing device 4Y.

  In the developing device 4Y, for example, a nonmagnetic one-component developer made of at least yellow toner is accommodated. The yellow toner is triboelectrically charged with the developing roll, has a charge of the same polarity as the charged electric charge on the photoreceptor 1Y, and is held on the developer roll (an example of a developer holding body). As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow toner image is formed continues to run at a predetermined speed, and the toner image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer position.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, 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 is applied to the toner image, so that the photoreceptor is exposed. The toner image on 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time is opposite in polarity to the toner.
On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

Further, 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.
Thus, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed and transferred in a multiple manner. The

  The intermediate transfer belt 20 on which the four color toner images are transferred in multiple ways through the first to fourth units is disposed on the image transfer surface side of the intermediate transfer belt 20, the support roll 24 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roll (an example of a secondary transfer unit) 26 is formed to a secondary transfer portion configured. On the other hand, recording paper (an example of a recording medium) P is fed at a predetermined timing into a gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact with each other via a supply mechanism, and the secondary transfer bias is supplied 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 is applied to the toner image, and the toner image on the intermediate transfer belt 20 is transferred onto the recording paper P. Is transcribed.

  Thereafter, the recording paper P is fed into the pressure contact portions (nip portions) of a pair of fixing rolls in a fixing device (an example of a fixing unit) 28, and the toner image is fixed on the recording paper P to form a fixed image.

Examples of the recording paper P to 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, the recording medium may be an OHP sheet.
In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper P is also preferably smooth. For example, coated paper with the surface of plain paper coated with resin, art paper for printing, etc. are preferably used. Is done.

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

<Process cartridge>
The process cartridge according to this embodiment will be described.
The process cartridge according to the present embodiment accommodates the electrostatic image developer according to the present embodiment, and develops the electrostatic image formed on the surface of the image carrier as a toner image by the electrostatic image developer. And a process cartridge that can be attached to and detached from the image forming apparatus.

  Note that the process cartridge according to the present embodiment is not limited to the above-described configuration, and other means such as a developing device and other units such as an image carrier, a charging unit, an electrostatic charge image forming unit, and a transfer unit, if necessary. And at least one selected from the above.

  Hereinafter, an example of the process cartridge according to the present embodiment will be shown, but the present invention is not limited to this. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

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

  Hereinafter, although an Example and a comparative example are given and this embodiment is described in detail in detail, this embodiment is not limited to these Examples at all. The “part” means “part by mass” unless otherwise specified.

[Preparation of polyester resin particle dispersion]
(Preparation of polyester resin particle dispersion 1)
Polyester resin 1 (glass transition temperature 59 ° C., weight average molecular weight (Mw) 46,000) was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A 0.37 mass% diluted ammonia water diluted with ion-exchanged water is added to a separately prepared aqueous medium tank and heated at 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute. The resin melt was transferred to the Cavitron at the same time. The Cavitron was operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² to obtain a polyester resin particle dispersion 1 having a volume average particle size of 220 nm and a solid content of 20% by mass.

(Preparation of polyester resin particle dispersion 2)
Polyester resin 2 (glass transition temperature 51 ° C., weight average molecular weight (Mw) 34,000) was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A 0.37 mass% diluted ammonia water diluted with ion-exchanged water is added to a separately prepared aqueous medium tank and heated at 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute. The resin melt was transferred to the Cavitron at the same time. The Cavitron was operated under conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm 2 to obtain a polyester resin particle dispersion 2 having a volume average particle size of 180 nm and a solid content of 20% by mass.

[Preparation of colorant particle dispersion]
(Preparation of colored particle dispersion 1)
Carbon black (Mitsubishi Chemical Corporation, trade name # 25B): 20 parts Anionic surfactant (Neogen SC, Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts Ion-exchanged water: 80 parts The components were mixed and dispersed for 1 hour with a high-pressure impact disperser Ultimizer (HJP 30006, manufactured by Sugino Machine Co., Ltd.) to obtain a colorant particle dispersion 1 having a volume average particle size of 180 nm and a solid content of 20% by mass.

[Preparation of release agent particle dispersion]
(Preparation of release agent particle dispersion 1)
-Paraffin wax (Nippon Seiki Co., Ltd., trade name HNP9): 20 parts-Anionic surfactant (Neogen SC, Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts-Ion-exchanged water: 80 parts The ingredients were mixed, heated to 100 ° C., sufficiently dispersed with IKA Ultra Turrax T50, and then dispersed with a pressure discharge type gorin homogenizer, and a release agent having a volume average particle size of 200 nm and a solid content of 20% by mass. A particle dispersion was obtained.

[Preparation of Charge Control Agent Particle Dispersion]
(Preparation of charge control agent particle dispersion 1)
-Charge control agent: 20 parts (made by Orient Chemical Industry Co., Ltd., trade name BONTRON N-01)
Anionic surfactant: 2 parts (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
-Ion-exchanged water: 80 parts After the above components were heated to 120 ° C and sufficiently dispersed with IKA Ultra Turrax T50, they were dispersed with a pressure discharge type homogenizer, and the volume average particle diameter reached 180 nm. It was collected. Thus, a charge control agent particle dispersion 1 having a solid content of 20% by mass was obtained.

[Example 1]
(Preparation of toner particles 1)
-Polyester resin particle dispersion 1: 63 parts-Colorant particle dispersion: 5 parts-Release agent dispersion: 7 parts-Charge control agent particle dispersion: 1 part-Ion exchange water: 60 parts It put in the flask made and fully mixed and disperse | distributed with the ultra turrax T50. Next, 0.4 part of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Further, the flask was heated to 55 ° C. with stirring in an oil bath for heating. After maintaining at 55 ° C. for 2 hours, 16 parts of the polyester resin particle dispersion liquid 1 and 8 parts of the polyester resin particle dispersion liquid 2 were gradually added thereto.
Thereafter, the pH of the system was adjusted to 8.2 with a 0.5N aqueous sodium hydroxide solution, and then the stainless steel flask was sealed, heated to 88 ° C. while continuing stirring using a magnetic seal, and maintained for 3 hours.
After completion of the reaction, the mixture was cooled, filtered, thoroughly washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. Next, vacuum drying was performed for 12 hours to obtain toner particles 1 having a volume average particle diameter D50 of 6.3 μm.

(Preparation of non-magnetic one-component developer)
Toner particles 1: 100 parts Silica particles 1: 1.3 parts (manufactured by Clariant Japan, trade name H13TA, number average particle diameter 20 nm)
Boron nitride particles: 0.7 parts (manufactured by Showa Denko KK, trade name UHP-1K, number average particle size 8 μm)
The above composition was mixed with a Henschel mixer to obtain a toner. The obtained toner was used as the nonmagnetic one-component developer of Example 1.

[Example 2]
In Example 1, except that the boron nitride particles were changed to molybdenum disulfide particles (manufactured by Sumiko Lubricant Co., Ltd., trade name: Mori powder, number average particle size 5 μm), the same as in Example 1, A toner was obtained. The obtained toner was used as the nonmagnetic one-component developer of Example 2.

[Example 3]
In Example 1, except that the boron nitride particles were changed to tungsten disulfide particles (manufactured by Nippon Lubricant Co., Ltd., trade name: Tanmic A, number average particle diameter 2 μm), toner was obtained in the same manner as in Example 1. Got. The obtained toner was used as the nonmagnetic one-component developer of Example 3.

[Example 4]
In Example 1, except that the boron nitride particles were changed to calcium stearate particles (manufactured by NOF Corporation, trade name: Nissan Electol MC-2, number average particle size 2 μm), the same as in Example 1. A toner was obtained. The obtained toner was used as the nonmagnetic one-component developer of Example 4.

[Example 5]
In Example 1, except that the boron nitride particles were changed to magnesium stearate particles (manufactured by NOF Corporation, trade name: Nissan Electol MM-2, number average particle diameter 2 μm), the same as in Example 1. The toner was obtained. The obtained toner was used as the nonmagnetic one-component developer of Example 5.

[Example 6]
In Example 1, except that the boron nitride particles were changed to zinc laurate particles (manufactured by Sakai Chemical Industry Co., Ltd., trade name: Z-12, number average particle size 2 μm), the same as in Example 1, A toner was obtained. The obtained toner was used as the nonmagnetic one-component developer of Example 6.

[Example 7]
(Preparation of toner particles 2)
-Polyester resin particle dispersion 1: 63 parts-Colorant particle dispersion: 5 parts-Release agent dispersion: 7 parts-Charge control agent particle dispersion: 1 part-Ion exchange water: 60 parts It put in the flask made and fully mixed and disperse | distributed with the ultra turrax T50. Next, 0.4 part of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Further, the flask was heated to 55 ° C. with stirring in an oil bath for heating. After maintaining at 55 ° C. for 2 hours, 20 parts of polyester resin particle dispersion liquid 1 and 4 parts of polyester resin particle dispersion liquid 2 were gradually added thereto.
Thereafter, the pH of the system was adjusted to 8.2 with a 0.5N aqueous sodium hydroxide solution, and then the stainless steel flask was sealed, heated to 88 ° C. while continuing stirring using a magnetic seal, and maintained for 3 hours.
After completion of the reaction, the mixture was cooled, filtered, thoroughly washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. Next, vacuum drying was performed for 12 hours to obtain toner particles 2 having a volume average particle diameter D50 of 6.5 μm.

(Preparation of non-magnetic one-component developer)
A toner was obtained in the same manner as in Example 1 except that the toner particles 1 were changed to the toner particles 2 in Example 1. The obtained toner was used as the nonmagnetic one-component developer of Example 7.

[Example 8]
(Preparation of toner particles 3)
-Polyester resin particle dispersion 1: 63 parts-Colorant particle dispersion: 5 parts-Release agent dispersion: 7 parts-Charge control agent particle dispersion: 1 part-Ion exchange water: 60 parts It put in the flask made and fully mixed and disperse | distributed with the ultra turrax T50. Next, 0.4 part of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Further, the flask was heated to 55 ° C. with stirring in an oil bath for heating. After maintaining at 55 ° C. for 2 hours, polyester resin particle dispersion 1:14 parts and polyester resin particle dispersion 2:10 parts were gradually added thereto.
Thereafter, the pH of the system was adjusted to 7.8 with a 0.5N aqueous sodium hydroxide solution, the stainless steel flask was sealed, heated to 91 ° C. while continuing stirring using a magnetic seal, and maintained for 4 hours.
After completion of the reaction, the mixture was cooled, filtered, thoroughly washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. Next, vacuum drying was performed for 12 hours to obtain toner particles 3 having a volume average particle diameter D50 of 6.6 μm.

(Preparation of non-magnetic one-component developer)
Then, a toner was obtained in the same manner as in Example 1 except that the toner particle 1 was changed to the toner particle 3 in Example 1. The obtained toner was used as the nonmagnetic one-component developer of Example 8.

[Example 9]
10 parts of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBE-903) are sprayed on 100 parts of silica particles (number average particle diameter 7 nm) produced by a gas phase method by spray drying. Then, the surface treatment of silica particles was performed. The surface-treated silica particles were crushed to obtain silica particles 2.
In Example 1, a toner was obtained in the same manner as in Example 1 except that 1.3 parts of silica particles 1 were changed to 1.1 parts of silica particles 2. The obtained toner was used as the nonmagnetic one-component developer of Example 9.

[Example 10]
A silica particle 3 was obtained in the same manner as the silica particle 2 except that the amount of 3-aminopropyltriethoxysilane was changed to 5 parts.
In Example 1, a toner was obtained in the same manner as in Example 1 except that 1.3 parts of silica particles 1 were changed to 2.5 parts of silica particles. The obtained toner was used as the nonmagnetic one-component developer of Example 10.

[Example 11]
(Preparation of toner particles 4)
-Polyester resin particle dispersion 1: 63 parts-Colorant particle dispersion: 5 parts-Release agent dispersion: 7 parts-Charge control agent particle dispersion: 1 part-Ion exchange water: 60 parts It put in the flask made and fully mixed and disperse | distributed with the ultra turrax T50. Next, 0.4 part of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Further, the flask was heated to 55 ° C. with stirring in an oil bath for heating. After maintaining at 55 ° C. for 2 hours, 16 parts of the polyester resin particle dispersion liquid 1 and 8 parts of the polyester resin particle dispersion liquid 2 were gradually added thereto.
Thereafter, the pH of the system was adjusted to 8.2 with a 0.5N aqueous sodium hydroxide solution, the stainless steel flask was sealed, heated to 86 ° C. while continuing stirring using a magnetic seal, and maintained for 2 hours.
After completion of the reaction, the mixture was cooled, filtered, thoroughly washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. Next, vacuum drying was performed for 12 hours to obtain toner particles 4 having a volume average particle diameter D50 of 6.3 μm.

(Preparation of non-magnetic one-component developer)
A toner was obtained in the same manner as in Example 1 except that the toner particles 1 were changed to the toner particles 4 in Example 1. The obtained toner was used as the nonmagnetic one-component developer of Example 11.

[Comparative Example 1]
(Preparation of toner particles 5)
-Polyester resin particle dispersion 1: 63 parts-Colorant particle dispersion: 5 parts-Release agent dispersion: 7 parts-Charge control agent particle dispersion: 1 part-Ion exchange water: 60 parts It put in the flask made and fully mixed and disperse | distributed with the ultra turrax T50. Next, 0.4 part of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Further, the flask was heated to 55 ° C. with stirring in an oil bath for heating. After maintaining at 55 ° C. for 2 hours, 21 parts of the polyester resin particle dispersion liquid 1: 3 parts and 3 parts of the polyester resin particle dispersion liquid 2 were gradually added thereto.
Thereafter, the pH of the system was adjusted to 8.2 with a 0.5N aqueous sodium hydroxide solution, and then the stainless steel flask was sealed, heated to 95 ° C. while continuing stirring using a magnetic seal, and maintained for 2 hours.
After completion of the reaction, the mixture was cooled, filtered, thoroughly washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. Next, vacuum drying was performed for 12 hours to obtain toner particles 5 having a volume average particle diameter D50 of 6.5 μm.
(Preparation of non-magnetic one-component developer)
A toner was obtained in the same manner as in Example 1 except that the toner particles 1 were changed to the toner particles 5 in Example 1. The obtained toner was used as the nonmagnetic one-component developer of Comparative Example 1.

[Comparative Example 2]
(Preparation of toner particles 6)
-Polyester resin particle dispersion 1: 63 parts-Colorant particle dispersion: 5 parts-Release agent dispersion: 7 parts-Charge control agent particle dispersion: 1 part-Ion exchange water: 60 parts It put in the flask made and fully mixed and disperse | distributed with the ultra turrax T50. Next, 0.4 part of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Further, the flask was heated to 55 ° C. with stirring in an oil bath for heating. After maintaining at 55 ° C. for 2 hours, 16 parts of the polyester resin particle dispersion liquid 1 and 8 parts of the polyester resin particle dispersion liquid 2 were gradually added thereto.
Then, after adjusting the pH of the system to 8.0 with a 0.5N aqueous sodium hydroxide solution, the stainless steel flask was sealed, heated to 87 ° C. while continuing stirring using a magnetic seal, and maintained for 1.5 hours. did.
After completion of the reaction, the mixture was cooled, filtered, thoroughly washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. Next, vacuum drying was performed for 12 hours to obtain toner particles 6 having a volume average particle diameter D50 of 6.4 μm.
(Preparation of non-magnetic one-component developer)
A toner was obtained in the same manner as in Example 1 except that the toner particles 1 were changed to the toner particles 6 in Example 1. The obtained toner was used as the nonmagnetic one-component developer of Comparative Example 2.

[Comparative Example 3]
In Example 1, a toner was obtained in the same manner as Example 1 except that boron nitride particles were not added. The obtained toner was used as the nonmagnetic one-component developer of Comparative Example 3.

[Comparative Example 4]
In Example 1, except that 1.3 parts of silica particles 1 were changed to 1.6 parts of titanium oxide particles (trade name JMT-150ANO, number average particle size 15 nm, manufactured by Teika Co., Ltd.) In the same manner as in Example 1, a toner was obtained. The obtained toner was used as the nonmagnetic one-component developer of Comparative Example 4.

[Comparative Example 5]
10 parts of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBE-903) are sprayed on 100 parts of silica particles (number average particle diameter 4 nm) produced by a gas phase method by spray drying. Then, the surface treatment of silica particles was performed. The surface-treated silica particles were crushed to obtain silica particles 4.
In Example 1, a toner was obtained in the same manner as in Example 1 except that 1.3 parts of silica particles 1 were changed to 1.1 parts of silica particles 4. The obtained toner was used as the nonmagnetic one-component developer of Comparative Example 5.

[Comparative Example 6]
To 100 parts of silica particles (number average particle diameter 65 nm) produced by a gas phase method, 5 parts of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBE-903) is sprayed by spray drying. Then, the surface treatment of silica particles was performed. The surface-treated silica particles were crushed to obtain silica particles 5.
A toner was obtained in the same manner as in Example 1 except that 1.3 parts of the silica particles 1 were changed to 2.5 parts of the silica particles 5 in Example 1. The obtained toner was used as the nonmagnetic one-component developer of Comparative Example 5.

[Evaluation]
The following evaluation was performed on the nonmagnetic one-component developer obtained in each example.

(Measurement of toner particle characteristics)
The characteristics of the toner particles of the nonmagnetic one-component developer obtained in each example were examined according to the method described above. Specifically, the average circularity of all toner particles and the ratio of toner particles A having one or more depressions having a depth of 0.2 μm or more on the surface were examined.

(Color streak and color point evaluation)
The non-magnetic one-component developer obtained in each example was filled in a developing device of a modified machine of “DocuPrint P300d” manufactured by Fuji Xerox Co., Ltd., which is a non-magnetic one-component system. This modified machine is modified so that the process speed is variable.
Using this modified machine, 1000 A4 halftone images with an image density of 2% were printed continuously in a high-temperature environment at a temperature of 35 ° C and a humidity of 70%. The presence or absence of points was visually evaluated.
A: A color image and a color point are not recognized at all, and a very good image is obtained.
B: Color streaks and color points are recognized only slightly, but at a sufficiently acceptable level, and a good image is obtained.
C: Color streaks and color points are slightly recognized but at an acceptable level.
D: Color streaks and color points are clearly recognized visually.

  From the above results, it can be seen that in this embodiment, the generation of color streaks and color points is suppressed as compared with the comparative example.

1Y, 1M, 1C, 1K, photoconductor (an example of an image carrier)
2Y, 2M, 2C, 2K, charging roll (an example of charging means)
3. Exposure device (an example of electrostatic charge image forming means)
3Y, 3M, 3C, 3K Laser beams 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)
10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt (an example of an intermediate transfer member)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
30 Intermediate transfer member cleaning device 107 Photosensitive member (an example of an image holding member)
108 Charging roll (an example of charging means)
109 Exposure apparatus (an example of electrostatic charge image forming means)
111 Developing device (an example of developing means)
112 Transfer device (an example of transfer means)
113 photoconductor cleaning device (an example of cleaning means)
115 Fixing device (an example of fixing means)
116 Attachment rail 118 Opening 117 for exposure 117 Case 200 Process cartridge 300 Recording paper (an example of recording medium)
P Recording paper (an example of a recording medium)

Claims (4)

Toner particles having one or more depressions having a depth of 0.2 μm or more on the surface and containing 52 number% or more of all toner particles, and the average circularity of all toner particles being 0.970 or more,
At least one external additive selected from the group consisting of external additive A composed of silica particles having a number average particle diameter of 5 nm to 60 nm, and fatty acid metal salt particles, molybdenum disulfide particles, tungsten disulfide particles, and boron nitride particles. An external additive containing Agent B,
A non-magnetic one-component developer. A developing means for accommodating the non-magnetic one-component developer according to claim 1 and developing the electrostatic image formed on the surface of the image carrier as a toner image by the non-magnetic one-component developer,
A process cartridge attached to and detached from the image forming apparatus. An 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;
A developing unit that contains the non-magnetic one-component developer according to claim 1 and that develops an electrostatic image formed on the surface of the image carrier as a toner image by the non-magnetic one-component developer;
Transfer means for transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising: A charging step for 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, as a toner image, an electrostatic image formed on the surface of the image carrier with the nonmagnetic one-component developer according to claim 1;
A transfer step of transferring a 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: