JP5531628B2 - Developer for developing electrostatic charge, developer cartridge, process cartridge, and image forming apparatus - Google Patents

Description

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

  A method of visualizing image information through an electrostatic charge image such as electrophotography is currently used in various fields. In conventional electrophotography, an electrostatic charge image is formed on a photosensitive member or electrostatic recording member using various means, and electrostatic charge particles called toner are attached to the electrostatic charge image to develop the electrostatic charge image. Then, a method is generally used in which a toner image is visualized through a plurality of steps of transferring the toner image to the surface of a transfer medium and fixing it by heating or the like.

  Conventionally, techniques for externally adding higher fatty acids or higher fatty acids into the toner as lubricants have been proposed (see, for example, Patent Documents 1 to 7).

JP 2001-42562 A JP-A-2005-250403 JP 2008-298993 A JP 2006-220844 A JP 2007-79333 A JP 2006-85042 A JP 2006-267299 A

  An object of the present invention is to combine a toner containing at least an external additive having a number average particle diameter of 100 nm or more and 800 nm or less, a carrier having a shape factor SF2 of 100 or more and 120 or less, and particles comprising a higher fatty acid. It is an object to provide a developer for electrostatic charge development in which fluctuations in image density over time are suppressed as compared to a developer for electrostatic charge development that does not occur.

The above problem is solved by the following means. That is,
The invention according to claim 1
Toner containing at least toner particles and an external additive having a number average particle diameter of 100 nm to 800 nm;
A carrier having a shape factor SF2 of 100 or more and 120 or less;
Particles composed of a higher fatty acid having 12 to 22 carbon atoms ;
Have a content of particles composed include the higher fatty acid for the entire electrostatic latent image developing developer is 1 wt% or less than 0.08 wt%, an electrostatic developer for developing.

The invention according to claim 2
The developer for electrostatic charge development according to claim 1, wherein a melting temperature of particles composed of the higher fatty acid is 40 ° C. or higher and 80 ° C. or lower.

The invention according to claim 3
3. The developer for electrostatic charge development according to claim 1, wherein the number average particle diameter of the particles composed of the higher fatty acid is 1 μm or more and 15 μm or less.

The invention according to claim 4
Containing the developer for electrostatic charge development according to any one of claims 1 to 3,
A developer cartridge that is detachable from the image forming apparatus.

The invention according to claim 5
Development in which the developer for electrostatic charge development according to any one of claims 1 to 3 is accommodated and an electrostatic charge image formed on an image carrier is developed as a toner image by the developer for electrostatic charge development. With means,
A process cartridge that is detachable from the image forming apparatus.

The invention according to claim 6
An image carrier,
Charging means for charging the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
4. The electrostatic charge developing developer according to claim 1 is accommodated, and the electrostatic charge image formed on the image carrier is developed as a toner image by the electrostatic charge developing developer. Developing means,
Transfer means for transferring the toner image formed on the image carrier onto a transfer target;
Fixing means for fixing the toner image transferred onto the transfer target;
An image forming apparatus.

According to the first aspect of the present invention, particles comprising a toner containing at least an external additive having a number average particle size of 100 nm to 800 nm, a carrier having a shape factor SF2 of 100 to 120, and a higher fatty acid. As compared with an electrostatic charge developing developer that does not combine the above, fluctuations in image density over time are suppressed.
According to the second aspect of the present invention, fluctuations in image density over time can be suppressed as compared with the case where the melting temperature of the particles composed of higher fatty acids is not 40 ° C. or higher and 80 ° C. or lower.
According to the third aspect of the present invention, fluctuations in image density over time are suppressed as compared with the case where the number average particle diameter of the particles composed of higher fatty acids is not 1 μm or more and 15 μm or less.
According to the inventions according to claims 4, 5, and 6, the toner includes at least an external additive having a number average particle diameter of 100 nm to 800 nm, a carrier having a shape factor SF2 of 100 to 120, and a higher fatty acid. Compared with the case where a developer for electrostatic charge development that does not combine with the constituted particles is applied, fluctuations in image density over time are suppressed.

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. It is a schematic diagram showing a state in which the magnetic brush (carrier) is easily deformed and the shape of the magnetic brush in contact with the image carrier (photoconductor) follows. It is a schematic diagram showing a state in which the magnetic brush (carrier) is not easily deformed and the shape of the magnetic brush contacting the image holding member (photosensitive member) does not follow.

(Developer for electrostatic charge development)
The developer for electrostatic charge development according to the exemplary embodiment includes toner, a carrier, and particles composed of a higher fatty acid (hereinafter sometimes referred to as higher fatty acid particles). The toner includes at least toner particles and an external additive having a number average particle diameter of 100 nm to 800 nm (hereinafter sometimes referred to as a large-diameter external additive), and the carrier has a shape factor SF2. The carrier is 100 or more and 120 or less (hereinafter sometimes referred to as a smooth carrier). In this embodiment, the higher fatty acid particles are particles that are not included as an external additive of the toner but are added as a third component to the toner and carrier in the developer.
Further, in the present embodiment, a mode in which the higher fatty acid particles have 12 to 22 carbon atoms and the content of the higher fatty acid particles with respect to the entire developer is 0.08% by mass to 1% by mass is applied.

In the developer for electrostatic charge development according to the present embodiment, the above configuration suppresses fluctuations in image density over time.
The reason for this is not clear, but is presumed to be as follows.

First, the large-diameter external additive having the above-mentioned number average particle diameter functions as a buffer member (spacer) on the surface of the toner particles, and is considered to reduce the adhesion between the toner particles and other members. For this reason, it is considered that the transfer efficiency from the image carrier (photosensitive member) is improved and blurring and unevenness during transfer are suppressed. Further, it is considered that the large-diameter external additive is not easily embedded in the toner even if it is stirred in the developing device, and the transfer efficiency is improved stably for a long period of time.
When a toner containing this large-diameter external additive is used, the toner image formed thereby tends to have a weak adhesive force with the image carrier (photoreceptor), and linearly rises on the development carrier. It is considered that the toner image is likely to be disturbed by a plurality of carriers (hereinafter referred to as a magnetic brush) connected in a shape (see FIG. 4).
When a carrier having the above shape factor (hereinafter referred to as a smooth carrier) is used, since the smooth carrier has less surface irregularities, the friction between the carriers of the magnetic brush is reduced, the magnetic brush is easily deformed, and the image is retained. It is considered that the shape of the magnetic brush that comes into contact with the body (photosensitive body) comes to follow (see FIG. 3). As a result, it is considered that the toner image is hardly disturbed by the magnetic brush.

  On the other hand, when the smooth carrier is used, it is considered that the contact between the carriers in the magnetic brush is reduced because the carrier has less surface irregularities. For this reason, when the large-diameter external additive released from the toner (toner particles) adheres to the surface of the carrier, it is considered that a magnetic brush is easily formed with the large-diameter external additive interposed between the carriers. Since this large-diameter external additive has a higher electrical resistance than the carrier, if a large-diameter external additive is interposed between the carriers of the magnetic brush, the electrical resistance of the magnetic brush tends to increase over time, and the time It is considered that fluctuations in image density are likely to occur due to the passage of time.

When higher fatty acid particles are added to a system having a toner containing the above-mentioned large-diameter external additive and a smooth carrier having the above shape factor, the high-fatty fatty acid particles facilitate removal of the large-diameter external additive attached to the carrier. Conceivable. The higher fatty acid particles are softer and easier to deform than the carriers, external additives, and toner particles, and are lighter in weight. In the state where higher fatty acid particles having such properties are added, for example, when the developer collides with a large-diameter external additive electrostatically attached to the carrier by stirring in the developing device, the carrier does not move and collides. It is considered that all the forces are concentrated at the contact portion between the higher fatty acid particles and the large-diameter external additive. Then, it is considered that the higher fatty acid particles colliding with the large-diameter external additive are deformed, and the large-diameter external additive is irreversibly attached to the surface of the higher fatty acid particles. Since the irreversible adhesion between the higher fatty acid particles and the large-diameter external additive is stronger than the electrostatic adhesion between the carrier and the large-diameter external additive, the large-diameter external additive is removed from the carrier. it is conceivable that. Since the adhesion of the large-diameter external additive to the carrier is suppressed, it is considered that the large-diameter external additive is difficult to intervene between the carriers of the magnetic brush, and the increase in the electric resistance of the magnetic brush is suppressed.
The toner particles and the higher fatty acid particles have a small weight difference (for example, the specific gravity is about 1.1 g / cm ³ for the polystyrene resin toner and the specific gravity is about 1.2 g / cm ³ for the polyester resin toner. specific gravity 0.9 g / cm ³ or so) it, also the toner particles and a higher fatty acid particles collide, the collision force will be consumed in the movement and transfer of the toner particles, the surface of the higher fatty acid particles are deformed It is considered that the irreversible adhesion caused by is unlikely to occur.

From the above, it is considered that the change in image density over time is suppressed in the developer for electrostatic charge development according to this embodiment.
For the same reason as described above, in the developer for electrostatic charge development according to the present embodiment, the toner image is easily disturbed by the magnetic brush, so that the image density unevenness in an image such as a solid image or a halftone image, It is thought that disturbances and interruptions of fine wires are also suppressed.

Hereinafter, details of each material will be described.
First, the higher fatty acid particles will be described.
Higher fatty acid particles are particles composed of higher fatty acids.
The higher fatty acid particles preferably have a melting temperature of 40 ° C. or higher and 80 ° C. or lower, more preferably 45 ° C. or higher and 70 ° C. or lower, and further preferably 50 ° C. or higher and 65 ° C.
When the melting temperature of the higher fatty acid particles is in the above range, it is considered that when the higher fatty acid particles collide with the large-diameter external additive, the higher fatty acid particles are easily deformed and irreversibly adhere to the large-diameter external additive. As a result, the ability to capture large-diameter external additives by higher fatty acid particles is improved, and as a result, surface adhesion to the carrier of large-diameter external additives is suppressed, and fluctuations in image density over time are easily suppressed. Become. On the other hand, if the melting temperature of the higher fatty acid particles is too low, in-machine contamination due to the higher fatty acid particles tends to occur.
The melting temperature of the higher fatty acid particles is controlled, for example, by adjusting the carbon number, weight molecular weight, etc. of the higher fatty acid used.

  Here, the melting temperature of the higher fatty acid is measured using a differential scanning calorimeter (for example, manufactured by Mac Science: DSC3110, thermal analysis system 001, etc.) from 0 ° C. to 150 ° C. under a temperature increase rate of 10 ° C./min. Obtained from the DSC spectrum obtained by measurement.

The higher fatty acid particles preferably have a particle size smaller than that of the carrier and larger than that of the large-diameter external additive. Specifically, the number average particle size is desirably 1 μm or more and 15 μm or less. It is desirably 3 μm or more and 14 μm or less, and more desirably 5 μm or more and 12 μm or less.
When the number average particle diameter of the higher fatty acid particles is within the above range, when the higher fatty acid particles collide with the large-diameter external additive, a surface area that contacts the large-diameter external additive is secured, and the impact force is large-diameter external additive. Since it is easy to concentrate on the agent, it is considered that irreversible adhesion to the large-diameter external additive is likely to occur due to deformation. As a result, the capture function of the large-diameter external additive by the higher fatty acid particles is improved. As a result, adhesion of the surface of the large-diameter external additive to the carrier is suppressed, and fluctuations in image density over time are easily suppressed. Become. On the other hand, if the number average particle size of the higher fatty acid particles is too small, the fluidity of the developer may be deteriorated.

The number average particle diameter of the higher fatty acid particles is determined as follows. For example, with respect to the particle size range (channel) divided based on the particle size distribution measured by a measuring instrument such as Coulter Counter TAII, Multisizer II (manufactured by Beckman-Coulter), several particle diameters are respectively measured from the smaller diameter side. drawing a cumulative distribution, the number D _50P the particle diameter at a cumulative 50% is used as the number average particle diameter of the higher fatty acid particles.

As the higher fatty acid, for example, a linear saturated monocarboxylic acid has 12 to 22 carbon atoms (preferably 12 to 18 or less, more preferably 14 to 16 or less), and a molecular weight of 200 to 240 (preferably 200 or more). 284 or less, more desirably 228 or more and 256 or less) fatty acids.
Specific examples of higher fatty acids include saturated fatty acids (for example, lauric acid, myristic acid, palmitic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, caprylic acid, capric acid, daturic acid, stearic acid, montanic acid. , Melicic acid, etc.), unsaturated fatty acids (eg, elaidic acid, linoleic acid, linolenic acid, Linderic acid, mascoic acid, oleic acid, gadoleic acid, erucic acid, brassic acid, etc.). These fatty acids may be used alone or in a mixture.
Among these, as the higher fatty acid, it is preferable to use a linear saturated monocarboxylic acid alone. When this linear saturated monocarboxylic acid is applied, a decrease in the fluidity of the developer and the occurrence of contamination on the member are suppressed.

  The method for producing higher fatty acid particles is, for example, a method of pulverizing a lump of higher fatty acid using a dry pulverizer or a lump of high fatty acid dispersed in water and using a disperser under conditions at or above the melting temperature. A well-known method such as a method of preparing a dispersion liquid and then pulverizing it by freeze drying or the like can be used.

The content of the higher fatty acid particles is preferably 0.01% by weight or more and 1% by weight or less, more preferably 0.04% by weight or more and 0.5% by weight or less with respect to the whole developer.
However, the content of higher fatty acid particles is, for example, 0.01% by weight with respect to the whole developer, 0.2% by weight with respect to the toner (toner concentration of the developer is 5% by weight). On the other hand, in the case of 0.04% by weight, 0.5% by weight (toner concentration of the developer is 8% by weight) with respect to the toner, and in the case of 0.5% by weight with respect to the whole developer, the content of the toner is 0.8%. 5% by mass (toner concentration of developer 10% by mass), 1% by weight with respect to the whole developer, 7% by mass (toner concentration of developer 15% by mass), etc. It is preferable to adjust to a desired density according to the toner density.
By setting the content of the higher fatty acid particles in the above range, adhesion of the surface of the large-diameter external additive to the carrier is suppressed, and fluctuations in image density over time are easily suppressed. If the content of the higher fatty acid particles is too large, the fluidity of the developer tends to be lowered, and the toner may blow out due to poor mixing of the toner and the carrier.

Next, the toner will be described.
The toner includes, for example, toner particles, a large-diameter external additive, and other external additives as necessary.

First, toner particles will be described.
The toner particles include at least a binder resin, and may include a colorant, a release agent, and other internal additives as necessary.

  The binder resin is not particularly limited. For example, styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, acrylic Esters having vinyl groups such as lauryl acid, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; single quantities of polyolefins such as ethylene, propylene and butadiene Homopolymer consisting of, or copolymers obtained by combining two or more of these, more mixtures thereof. In addition, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, or a mixture of these with the vinyl resin, or vinyl monomers in the presence of these resins Examples thereof include a graft polymer obtained by polymerization.

Styrene resin, (meth) acrylic resin, and styrene- (meth) acrylic copolymer resin are obtained by known methods, for example, by combining styrene monomers and (meth) acrylic acid monomers alone or in appropriate combination. It is done. “(Meth) acryl” is an expression including both “acryl” and “methacryl”.
The polyester resin can be obtained by selecting and combining suitable ones from a dicarboxylic acid component and a diol component and synthesizing them using a conventionally known method such as a transesterification method or a polycondensation method.

  When using a styrene resin, a (meth) acrylic resin or a copolymer resin thereof as a binder resin, the weight average molecular weight Mw is 20,000 or more and 100,000 or less, and the number average molecular weight Mn is 2,000 or more and 30,000 or less. It is preferable to use the thing of the range. On the other hand, when a polyester resin is used as the binder resin, a resin having a weight average molecular weight Mw of 5,000 or more and 40,000 or less and a number average molecular weight Mn of 2,000 or more and 10,000 or less may be used. preferable.

  The glass transition temperature of the binder resin is desirably in the range of 40 ° C. or higher and 80 ° C. or lower. When the glass transition temperature is in the above range, the heat-resistant blocking property and the minimum fixing temperature are maintained.

  The colorant is not particularly limited as long as it is a known colorant. For example, carbon black such as furnace black, channel black, acetylene black, and thermal black, inorganic pigments such as bengara, bitumen, and titanium oxide, fast yellow, disazo Azo pigments such as yellow, pyrazolone red, chelate red, brilliant carmine, para brown, phthalocyanine pigments such as copper phthalocyanine, metal-free phthalocyanine, flavantron yellow, dibromoanthrone orange, perylene red, quinacridone red, dioxazine violet Examples thereof include cyclic pigments.

  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.

  As content of a coloring agent, the range of 1 to 30 mass parts is desirable with respect to 100 mass parts of binder resin.

  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; ester types such as fatty acid esters and montanic acid esters. Wax; and the like, but is not limited thereto.

  The melting point of the release agent is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher, from the viewpoint of storage stability. Further, from the viewpoint of offset resistance, the temperature is desirably 110 ° C. or less, and more desirably 100 ° C. or less.

  The content of the release agent is preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 12% by mass or less, and further more preferably 3% by mass or more and 10% by mass or less.

  Examples of other internal additives include magnetic materials, charge control agents, inorganic powders, and the like.

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

The volume average particle diameter of the toner particles is measured using a Coulter Multisizer-II type (manufactured by Beckman Coulter, Inc.) with an aperture diameter of 50 μm. At this time, the measurement is performed after the toner particles are dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.
As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant, and this is added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of the particles is measured. The number of particles to be measured is 50,000.
For the measured particle size distribution, a cumulative distribution is drawn from the smaller diameter side with respect to the divided particle size range (channel), and the particle size at which 50% is accumulated is defined as the volume average particle size.

Next, the large diameter external additive will be described.
The large-diameter external additive has a number average particle diameter of 100 nm to 800 nm, preferably 120 nm to 700 nm, more preferably 140 nm to 500 nm.
When the large-sized external additive particles are in the above range, they are not easily released from the toner particles, exhibit a spacer effect, and improve transfer efficiency.

  The number average particle diameter of the large-diameter external additive is determined as follows. Using a scanning electron microscope (for example, manufactured by Hitachi, Ltd .: S-4100, etc.), the external additive was observed to take an image, and this image was taken into an image analyzer (for example, LUZEX III, manufactured by Nireco). The equivalent-circle diameter of the primary particles is measured, the average value is obtained, and the number-average particle diameter of the primary particles is obtained. In the electron microscope, the magnification was adjusted so that 10 or more and 50 or less external additives could be seen in one field of view, and the equivalent circle diameter of the primary particles was determined by observing multiple fields of view.

  Examples of the large external additive include metal oxide particles (for example, silica particles, titania particles, alumina particles, cerium oxide particles, etc.), resin particles (for example, polystyrene particles, acrylic resin particles, polyester particles, urethane particles, crosslinkable resins). Particles) and composite particles (for example, strontium titanate particles, calcium titanate particles, silicon carbide particles, etc.). These may be used alone or in combination of two or more.

  Among these particles, as the large-diameter external additive, for example, silica particles are preferable from the viewpoint of strength, small influence on color gamut, safety, cost, and the like, from the viewpoint of particle size distribution controllability. Therefore, silica particles by a sol-gel method or a wet method are particularly preferable.

  These particles may be subjected to a surface treatment. Examples of the surface treatment include surface treatment with a coupling agent (for example, silane coupling agent, titanate coupling agent, etc.), silicone oil, fatty acid metal salt, charge control goods and the like.

  The content of the large-diameter external additive is desirably 0.5 parts by mass or more and 5 parts by mass or less, and more desirably 1 part by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the toner particles.

Examples of other external additives include external additives (hereinafter referred to as small-diameter external additives) having a number average particle size of less than 50 nm (desirably 5 nm or more and 30 nm or less).
As the small-diameter external additive, for example, silica particles, alumina particles, titanium oxide particles, barium titanate particles, magnesium titanate particles, calcium titanate particles, strontium titanate particles, zinc oxide particles, silica sand particles, clay particles, Mica particles, wollastonite particles, diatomaceous earth particles, cerium chloride particles, bengara particles, chromium oxide particles, cerium oxide particles, antimony trioxide particles, magnesium oxide particles, zirconium oxide particles, silicon carbide particles, silicon nitride particles, calcium carbonate Examples thereof include particles, magnesium carbonate particles, and calcium phosphate particles.
The amount of other external additives added is preferably 0.3 parts by weight or more and 3.0 parts by weight or less with respect to 100 parts by weight of the toner particles.

Thus, the toner can be obtained by externally adding an external additive to the toner particles after the toner particles are produced.
Examples of the method for producing the toner particles include a kneading and pulverizing method and a wet granulation method. Examples of the wet granulation method include known melt suspension methods, emulsion aggregation / unification methods, and dissolution suspension methods.
Examples of a method of externally adding an external additive to toner particles include a method of mixing with a known mixer such as a V-type blender, a Henschel mixer, or a Redige mixer.

Next, the carrier will be described.
The carrier has a shape factor SF2 of 100 or more and 120 or less, preferably 100 or more and 115 or less, and more preferably 100 or more and 110 or less. The carrier shape factor SF2 is an index which means that 100 is smooth with no irregularities on the surface, and the irregularities on the surface increase as the value increases.
By setting the carrier shape factor SF2 within the above range, the frictional resistance between the carriers of the magnetic brush can be easily reduced, and as a result, the toner image is prevented from being disturbed.
The adjustment of the shape factor SF2 of the carrier is adjusted by, for example, the firing conditions of the magnetic powder, the granulation conditions of the magnetic powder dispersed resin particles, the thickness of the resin layer covering the magnetic powder or the magnetic powder dispersed resin particles, and the like. .

The shape factor SF2 of the carrier is obtained as follows.
An image was taken by observing the carrier using a scanning electron microscope (for example, manufactured by Hitachi, Ltd .: S-4100, etc.), and this image was captured by an image analyzer (for example, LUZEXIII, manufactured by Nireco). For the carrier, SF2 is calculated based on the following equation, and the average value is obtained as the carrier shape factor SF2. In the electron microscope, the magnification was adjusted so that 3 or more and 20 or less external additives could be seen in one field of view, and the observation of a plurality of fields of view was combined to calculate SF2 based on the following formula.
Formula: Shape factor SF2 = “PM ² / (4 · A · π)” × 100
Here, in the formula, PM indicates the peripheral length of the carrier. A represents the projected area of the carrier. π represents a circumference ratio.

There is no restriction | limiting in particular as a carrier, A well-known carrier can be used. For example,
Examples thereof include magnetic powder, magnetic powder-dispersed resin particles in which magnetic powder is dispersed in a resin, and resin-coated carriers having magnetic powder or magnetic powder-dispersed resin particles as a core material and having a resin coating layer on the surface thereof.

  Examples of the magnetic powder (core material) include magnetic metals (eg, iron oxide, nickel, cobalt, etc.) and magnetic oxides (eg, ferrite, magnetite, etc.).

  The volume average particle size of the magnetic powder (core material) is preferably 10 μm or more and 500 μm or less, and more preferably 30 μm or more and 100 μm or less.

  Examples of the resin for dispersing the coating resin / magnetic powder include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene- Examples include, but are not limited to, acrylic acid copolymers, straight silicone resins comprising organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins, etc. is not.

  Examples of a method of coating the surface of the core material with a resin include a method of coating with a coating layer forming solution in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited, and may be selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific examples of the resin coating method for the core material include, for example, an immersion method in which the carrier core material is immersed in a coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the carrier core material, Examples include fluidized bed method in which the coating layer forming solution is sprayed in a state where the core material is suspended by flowing air, and the kneader coater method in which the core material of the carrier and the coating layer forming solution are mixed in the kneader coater to remove the solvent. It is done.

The volume resistivity of the carrier is preferably 1 × 10 ⁵ Ω · cm to 1 × 10 ¹⁵ Ω · cm, more preferably 1 × 10 ⁸ Ω · cm to 1 × 10 ¹⁴ Ω · cm, Desirably, it is 1 × 10 ⁸ Ω · cm or more and 1 × 10 ¹³ Ω · cm or less.
By setting the electric resistivity of the carrier within the above range, occurrence of white spots and fluctuations in image density are suppressed.

Here, the volume resistivity (Ωcm) of the carrier is measured as follows. The measurement environment is a temperature of 20 ° C. and a humidity of 50% RH.
A carrier to be measured is placed flatly on the surface of a circular jig provided with an electrode plate of 20 cm ² so as to have a thickness of about 1 mm to 3 mm, thereby forming a carrier layer. The 20 cm ² electrode plate is placed on this and the carrier layer is sandwiched. In order to eliminate the gap between the carriers, the thickness (cm) of the carrier layer is measured after a load of 4 kg is applied on the electrode plate placed on the carrier layer. Both electrodes above and below the carrier layer are connected to an electrometer and a high-voltage power generator. A high voltage is applied to both electrodes so that the electric field is 6000 V / cm, and the current value (A) flowing at this time is read to calculate the volume electric resistance (Ω · cm) of the carrier. The calculation formula of the volume resistivity (Ω · cm) of the carrier is as shown in the following formula.
Formula: R = E × 20 / (I−I ₀ ) / L
In the above formula, R is the volume resistivity (Ω · cm) of the carrier, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at the applied voltage of 0 V, and L is the carrier layer. Represents the thickness (cm). A coefficient of 20 represents the area (cm ² ) of the electrode plate.

  Here, the mixing ratio (mass ratio) of the toner and the carrier is preferably in the range of toner: carrier = 1: 100 to 30: 100, and more preferably in the range of 3: 100 to 20: 100.

(Image forming device)
Next, the image forming apparatus 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 image carrier, an electrostatic image forming unit that forms an electrostatic image on the surface of the charged image carrier, and an electrostatic charge developing device. Developing means for containing the developer and developing the electrostatic image formed on the image carrier as a toner image with the developer for electrostatic charge development, and the toner image formed on the image carrier on the transfer target And a fixing means for fixing the toner image transferred onto the transfer medium. The electrostatic charge developing developer according to the present embodiment is applied as the electrostatic charge developing developer.

  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 contains the developer for developing an electrostatic charge 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. The main parts shown in the figure will be described, and the description of the other parts will be omitted.

  FIG. 1 is a schematic configuration diagram showing a four-tandem color image forming apparatus. 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 main body of 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 driving roller 22 and a support roller 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other from the left to the right in the drawing. The vehicle travels in the direction toward the unit 10K. A force is applied to the support roller 24 in a direction away from the drive roller 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around the both. Further, 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 driving roller 22.
Further, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K of each unit 10Y, 10M, 10C, and 10K includes yellow, magenta, cyan, and developer cartridges 8Y, 8M, 8C, and 8K. A developer containing black toner of four colors can be supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first image that forms the yellow image disposed on the upstream side in the intermediate transfer belt traveling direction is formed. The unit 10Y will be described as a representative. Note that the second to fourth components are denoted by reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) in the same parts as the first unit 10Y. 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 photosensitive member 1Y, a charging roller 2Y for charging the surface of the photosensitive member 1Y to a predetermined potential, and the charged surface is exposed by a laser beam 3Y based on the color-separated image signal to form an electrostatic charge image. An exposure device (electrostatic image forming means) 3 for forming, a developing device (developing means) 4Y for supplying the charged toner to the electrostatic image and developing the electrostatic image, and transferring the developed toner image onto the intermediate transfer belt 20 A primary transfer roller 5Y (primary transfer unit) that performs the transfer and a photoconductor cleaning device (cleaning unit) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer are sequentially arranged.
The primary transfer roller 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 rollers 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roller 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 to a potential of about −600V to −800V by the charging roller 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (a resistance equivalent to that of a general resin), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3Y. 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 of a yellow print 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 in this way 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) by the developing device 4Y.

  In the developing device 4Y, for example, an electrostatic charge developing developer according to this embodiment including at least yellow toner and a carrier is accommodated. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged charge on the photoreceptor 1Y, and a developer roll (developer holder). Is held on. 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 roller 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image. Then, the toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time is a (+) polarity opposite to the polarity (−) of the toner, and is controlled to about +10 μA by the control unit (not shown) in the first unit 10Y, for example.
On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K after the second unit 10M is also controlled according to 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 onto which the four color toner images have been transferred through the first to fourth units is arranged on the image transfer surface side of the intermediate transfer belt 20, the support roller 24 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roller (secondary transfer means) 26 is connected to a secondary transfer portion. On the other hand, the recording paper (transfer object) P is fed at a predetermined timing to the gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are pressed against each other via the supply mechanism, and the secondary transfer bias is supported. Applied to the roller 24. The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P is applied to the toner image, and the transfer bias is applied to the intermediate transfer belt 20. The toner image is transferred onto the recording paper P. Note that the secondary transfer bias at this time is determined according to the resistance detected by a resistance detecting means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

  Thereafter, the recording paper P is fed to the pressure contact portion (nip portion) of the pair of fixing rolls in the fixing device (roll-type fixing means) 28, the toner image is heated, and the color-superposed toner image is melted to record the recording paper. Fixed onto P.

Examples of the transfer target to which the toner image is transferred include plain paper and OHP sheet used for electrophotographic copying machines, printers, and the like.
In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer target is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with a resin or the like, for printing Art paper or the like is preferably used.

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.
The image forming apparatus exemplified above is configured to transfer the toner image onto the recording paper P via the intermediate transfer belt 20, but the present invention is not limited to this configuration, and the toner image is directly transferred from the photoconductor. It may be a structure that is transferred to a recording sheet.

<Process cartridge, developer cartridge>
FIG. 2 is a schematic configuration diagram showing an embodiment of a preferred example of a process cartridge containing a developer for developing an electrostatic charge according to the present embodiment. In the process cartridge 200, a charging roller 108, a developing device 111, a photoconductor cleaning device 113, an opening 118 for exposure, and an opening 117 for static elimination exposure are combined using a mounting rail 116 together with the photoconductor 107. , And integrated. In FIG. 2, reference numeral 300 denotes a transfer target.
The process cartridge 200 is detachable from an image forming apparatus including a transfer device 112, a fixing device 115, and other components not shown.

  The process cartridge 200 shown in FIG. 2 includes a charging device 108, a developing device 111, a cleaning device 113, an opening 118 for exposure, and an opening 117 for static elimination exposure. Can be combined. In the process cartridge according to the present embodiment, in addition to the photosensitive member 107, the charging device 108, the developing device 111, the cleaning device (cleaning means) 113, the opening 118 for exposure, and the opening 117 for static elimination exposure. At least one selected from the group consisting of:

  Next, the developer cartridge according to this embodiment will be described. The developer cartridge according to the present embodiment is a developer cartridge that is detached from the image forming apparatus and contains at least a replenishment developer for electrostatic charge development to be supplied to a developing unit provided in the image forming apparatus. It is.

  The image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which the developer cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and the developing devices 4Y, 4M, 4C, and 4K are the respective developing devices. The developer cartridge corresponding to (color) is connected by a toner supply pipe (not shown). Further, when the amount of toner stored in the developer cartridge becomes low, the developer cartridge is replaced.

  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 the following examples. Unless otherwise specified, “part” and “%” are based on mass.

[Production of toner particles]
(Preparation of toner particles A)
-Adjustment of resin particle dispersion-
-Styrene 300 parts-Methyl methacrylate 80 parts-Acrylic acid 10 parts-Dodecanethiol 5 parts-Divinylbenzene 5 parts

The above components are mixed and dissolved. On the other hand, 6 parts by mass of an anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.) is dissolved in 550 parts by mass of ion-exchanged water. Was added, dispersed and emulsified, and 50 parts by mass of an ion exchange aqueous solution in which 6 parts by mass of ammonium persulfate was dissolved was added while slowly stirring and mixing for 10 minutes.
Next, after sufficiently replacing the system with nitrogen, the flask was heated in an oil bath while stirring to carry out emulsion polymerization.
As a result, a resin particle dispersion having a central particle diameter (volume average particle diameter) of 210 nm, a glass transition temperature of 58 ° C., and a weight average molecular weight Mw of 48,000 was obtained.

-Adjustment of colorant particle dispersion-
Cyan pigment (copper phthalocyanine) 35 parts by weight Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 6 parts by weight Ion-exchanged water 200 parts by weight

  The above components were mixed and dissolved, and dispersed by a homogenizer (Ultra Turrax manufactured by IKA) and ultrasonic irradiation to obtain a colorant particle dispersion liquid having a central particle diameter (volume average particle diameter) of 155 nm.

-Preparation of release agent particle dispersion-
-Paraffin wax (melting point: 66 degrees) 55 parts by mass-Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., solid content 65%) 2.0 parts by mass-Ion-exchanged water 200 parts by mass

  The composition was heated to 95 ° C. and sufficiently dispersed with IKA Ultra Turrax T50, and then dispersed with a pressure discharge type homogenizer, and the center particle size (volume average particle size) of the release agent particles was 310 nm. A release agent particle dispersion was obtained.

-Production of toner particles-
Resin particle dispersion 200 parts by weight Colorant particle dispersion 45 parts by weight Release agent particle dispersion 65 parts by weight Polyaluminum chloride (10% aqueous solution) 3.1 parts by weight Ion-exchanged water 400 parts by weight The components were thoroughly mixed and dispersed in a round stainless steel flask using an Ultra Turrax T50 manufactured by IKA, and then heated to 55 ° C. while stirring the flask in a heating oil bath. After maintaining at 55 ° C. (initial heating temperature), 100 parts by mass of the resin particle dispersion was gradually added thereto.
Then, after adjusting the pH in the system to 6.5 using a 0.5 mol / L sodium hydroxide aqueous solution, the stainless steel flask was sealed, and the stirring shaft seal was magnetically sealed while continuing stirring. Heated to 95 ° C. After completion of the reaction, the reaction mixture was cooled, filtered, sufficiently washed with ion exchange water, and solid-liquid separation was performed by Nutsche suction filtration. This was further redispersed with 3 L of ion exchange water at 45 ° C., and stirred and washed at 300 rpm for 15 minutes. This washing operation was further repeated 5 times, and No. 1 was obtained by Nutsche suction filtration. Solid-liquid separation was performed using 5A filter paper. Next, vacuum drying was continued for 12 hours to obtain toner particles.
The volume average particle diameter of the toner particles at this time was measured and found to be 6.3 μm. The number particle size distribution index GSDp was 1.22. When the shape was observed with a Luzex image analyzer manufactured by Luzex, it was observed that the shape factor SF1 of the particles was 111 and the potato shape was rounded.

[Preparation of large external additive (preparation)]
-Preparation (preparation) of large-diameter external additive A-
A stirrer, a dropping funnel, and a thermometer were set in a glass reactor, and 15 parts by mass of ethanol and 28 parts by mass of tetraethoxysilane were added and stirred at a rotation speed of 100 rpm while maintaining at 35 ° C. Next, 30 parts by mass of a 20% strength aqueous ammonia solution was dropped over 5 minutes while stirring was continued. The reaction was allowed to proceed for 1 hour, followed by centrifugation to remove the supernatant. Further, 100 parts by mass of toluene was added to prepare a suspension. After adding 60% by mass of hexamethyldisilazane to the solid content in the suspension, the mixture was reacted at 95 ° C. for 4 hours. Thereafter, the suspension was heated to remove toluene and dried, and then coarse powder was removed with a sieve mesh having a mesh size of 106 μm to obtain a large-diameter external additive A having a number average particle diameter of 145 nm.

-Preparation (preparation) of large-diameter external additive B-
-Styrene 220 parts by mass-Divinylbenzene 15 parts by mass-Acrylic acid 2 parts by mass The above components are mixed and dissolved, while 3 parts by weight of the anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.) is added to ion-exchanged water 600. An ion dissolved in 10 parts by weight of ammonium persulfate was placed in a 2 L flask, dispersed and emulsified by adding the above mixed solution, and stirred and mixed with a half-moon stirring blade at 10 rpm. 30 parts by mass of the exchange aqueous solution was added dropwise. The dropping of the ammonium persulfate solution was performed at a rate of 30 parts by mass / 60 minutes.
Next, after the inside of the system was replaced with nitrogen, the rotation speed of the stirring blade was set to 15 rpm, and the flask was stirred and heated in an oil bath at 80 ° C. for 24 hours to carry out emulsion polymerization to obtain a resin particle dispersed slurry.
The resin particle-dispersed slurry is centrifuged and the supernatant liquid is removed. Then, the resin particle-dispersed slurry is re-dispersed in ion-exchanged water at 25 ° C., which is 100 times the resin particle solid content, and the washing is repeated 5 times by repeating the centrifugation. The resin particles were washed and freeze-dried, and then the coarse powder was removed with a sieve mesh having a mesh size of 106 μm to obtain a large-diameter external additive B having a number average particle diameter of 556 nm.

-Preparation (preparation) of large-diameter external additive C-
Except for not using divinylbenzene and acrylic acid, using 10 parts by weight of Daupfax, and adding 50 parts by weight of an aqueous ammonium persulfate solution at a rate of 50 parts by weight / 50 minutes, Similarly, a large diameter external additive C having a number average particle diameter of 105 nm was obtained.

-Preparation (preparation) of large-diameter external additive D-
30 parts by mass of the large-diameter external additive C and 200 parts by mass of ion-exchanged water in which 10 parts by mass of polyvinyl alcohol having a saponification degree of 82 mol% were dissolved in a 2 L flask equipped with a stirrer and maintained at 25 ° C. The mixture was stirred at 100 rpm. Next, 5 parts by mass of divinylbenzene in which 0.1 part by mass of benzene peroxide was dissolved was dropped over 5 parts by mass / 60 minutes while stirring was continued. From 10 minutes after the start of dropping, the flask was heated to 75 ° C. at a heating rate of 5 ° C./10 minutes. After completion of the dropwise addition of divinylbenzene, the mixture was heated to 85 ° C. while stirring and held for 2 hours to obtain a resin particle dispersed slurry.
The resin particle-dispersed slurry is centrifuged and the supernatant liquid is removed. Then, the resin particle-dispersed slurry is re-dispersed in ion-exchanged water at 25 ° C., which is 100 times the resin particle solid content, and the washing is repeated 5 times by repeating the centrifugation. The resin particles were washed and freeze-dried, and then the coarse powder was removed with a sieve mesh having a mesh size of 106 μm to obtain a large-diameter external additive D having a number average particle diameter of 760 nm.

-Preparation (preparation) of large-diameter external additive E-
A large-diameter external additive E was obtained in the same manner as the large-diameter external additive A except that 30 parts by mass of an aqueous ammonia solution was added dropwise over 10 minutes.

-Preparation (preparation) of large-diameter external additive F-
A large-diameter external additive F having a number average particle size of 911 nm was obtained in the same manner as the large-diameter external additive A, except that 50 parts by mass of tetraethoxysilane and 60 parts by mass of an aqueous ammonia solution were added dropwise over 30 minutes.

[Creation of carrier]
-Production of carrier A-
Into a Henschel mixer, 500 parts by mass of spherical magnetite particle powder having a volume average particle size of 0.18 μm was added, and after sufficiently stirring, 5.0 parts by mass of a titanate coupling agent was added, and the temperature was raised to 95 ° C., By mixing and stirring for 30 minutes, spherical magnetite particles coated with a titanate coupling agent were obtained.
Subsequently, 6.0 parts by mass of phenol, 10 parts by mass of 30% formalin, 500 parts by mass of the magnetite particles, 7 parts by mass of 25% aqueous ammonia, and 400 parts by mass of water were placed in a 1 L four-necked flask and mixed and stirred. . Next, the temperature is raised to 90 ° C. over 60 minutes with stirring and reacted at the same temperature for 180 minutes, then cooled to 30 ° C., 500 ml of water is added, the supernatant is removed, and the precipitate is washed with water. did. This was dried at 180 ° C. under reduced pressure, and coarse powder was removed with a sieve mesh having an opening of 106 μm to obtain core particles A having an average particle size of 38 μm.
Next, 200 parts by mass of toluene and 35 parts by mass of a styrene-methacrylate copolymer (component molar ratio 10:90, weight average molecular weight 160,000) were stirred with a stirrer for 90 minutes to obtain a coated resin solution.
1000 parts by weight of the core particle A and 70 parts by weight of the above-mentioned coating resin solution are put into a vacuum degassing type kneader coater (rotor-wall clearance 35 mm) and stirred at 30 rpm for 30 minutes at 65 ° C. Was reduced to 88 ° C., and the toluene was distilled off, degassed and dried under reduced pressure. Further, the carrier A was adjusted by passing a mesh having an opening of 75 μm. The shape factor SF2 of the carrier A was 104.

-Production of carrier B-
Core material particles B were obtained in the same manner as the core material particles A except that the particle size of the spherical magnetite was 0.65 μm. The average particle diameter of the core particles was 41 μm.
Carrier B was obtained in the same manner as Carrier A, except that 1000 parts by mass of core material particle B and 15 parts by mass of the above-mentioned coated resin solution were used. The shape factor SF2 of the carrier B was 118.

-Production of carrier C-
Carrier C was obtained in the same manner as carrier A, except that sintered ferrite particles having an average particle diameter of 33 μm were used as the core material particles. The shape factor SF2 of the carrier C was 125.

[Preparation of higher fatty acid particles (preparation)]
-Production (preparation) of higher fatty acid particles A-
The linear saturated monocarboxylic acid having 14 carbon atoms was pulverized using a pin mill while being cooled to 10 ° C. using dry ice. Next, classification was performed with an air classifier while cooling in the same manner to obtain higher fatty acid particles A having a number average particle diameter of 7.8 μm. The melting temperature of this higher fatty acid was 54 ° C.

-Production (preparation) of higher fatty acid particles B-
A higher fatty acid particle B having a number average particle size of 5.5 μm was obtained in the same manner as the higher fatty acid particle A except that a linear saturated monocarboxylic acid having 18 carbon atoms was used. The melting temperature of this higher fatty acid was 70 degrees.

-Production (preparation) of higher fatty acid particles C-
Higher fatty acid particles C having a number average particle diameter of 11.8 μm were obtained in the same manner as the higher fatty acid particles A except that a linear saturated monocarboxylic acid having 12 carbon atoms was used. The melting temperature of this higher fatty acid was 44 degrees.

-Production (preparation) of higher fatty acid particles D-
A higher fatty acid particle D having a number average particle diameter of 8.5 μm was obtained in the same manner as the higher fatty acid particle A except that a linear saturated monocarboxylic acid having 20 carbon atoms was used. The melting temperature of this higher fatty acid was 76 degrees.

-Production (preparation) of higher fatty acid particles E-
Higher fatty acid particles E having a number average particle size of 10.0 μm were obtained in the same manner as the higher fatty acid particles A except that a linear saturated monocarboxylic acid having 22 carbon atoms was used. The melting temperature of this higher fatty acid was 82 degrees.

-Production (preparation) of higher fatty acid particles F-
12 parts by mass of a linear saturated monocarboxylic acid having 14 carbon atoms was added to 100 parts by mass of ion-exchanged water in which 2 parts by mass of an anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.) was dissolved, and the stirring speed was 250 rpm. And heated to 90 ° C. with stirring. Stirring was increased to 300 rpm, and 90 degreeC was hold | maintained for 30 minutes, and it cooled to 5 degreeC, stirring as it is. Centrifugation while maintaining at 5 ° C. to remove the supernatant, followed by lyophilization, followed by removal of coarse powder using a net having a mesh size of 106 μm to obtain higher fatty acid particles F having a number average particle size of 2.7 μm Obtained. The melting temperature of this higher fatty acid was 54 degrees.

-Production (preparation) of higher fatty acid particles G-
Higher fatty acid particles G having a number average particle diameter of 15.9 μm were obtained in the same manner as the higher fatty acid particles A except that the classification conditions were changed during wind classification. The melting temperature of this higher fatty acid was 54 degrees.

-Production (preparation) of higher fatty acid particles H-
The same as the higher fatty acid particles F except that the anionic surfactant Dowfax was heated at 90 ° C. to 6 parts by mass, and then stirred at 3500 rpm for 5 minutes using a homogenizer (manufactured by IKA: Ultra Turrax T50). The higher fatty acid particles H having a number average particle size of 0.75 μm were obtained. The melting temperature of this higher fatty acid was 54 degrees.

-Preparation (preparation) of higher fatty acid particles I-
Higher fatty acid particles I having a number average particle diameter of 17.2 μm were obtained in the same manner as the higher fatty acid particles A, except that the temperature when pulverizing using a pin mill was 25 ° C. and the classification conditions were changed during air classification. The melting temperature of this higher fatty acid was 54 degrees.

-Production (preparation) of higher fatty acid particles J-
Higher fatty acid particles J having a number average particle size of 8.1 μm are the same as those of the higher fatty acid particles A except that a linear monounsaturated monocarboxylic acid having 22 carbon atoms is used and the temperature during pin milling is 5 ° C. Got. The melting temperature of this higher fatty acid was 35 degrees.

[Examples 1-14, Comparative Examples 1-5]
100 parts by mass of toner particles A, a large external additive (type and amount according to Table 1), and 1 part by mass of hexamethyldisilazane-treated silica having a number average particle diameter of 8 nm are used at a peripheral speed of 20 m / s. After blending for 15 minutes, coarse particles were removed using a 45 μm mesh sieve to obtain a toner.
Then, 100 parts by mass of the obtained toner, the carrier (type / amount according to Table 1), and higher fatty acid particles (type / amount according to Table 1) were stirred for 20 minutes at 20 rpm using a V-blender. Each developer was obtained by sieving with a sieve having a mesh of 212 μm.

[Evaluation]
Prepared Fuji Xerox DocuCentre-IIIC3300 modified so that the desired image can be output at any number of times and at any process speed. A3 of Fuji Xerox color application paper “J” is placed in the paper container. For the developing device and the replenishing cartridge, a modified machine in which the developer and toner obtained in each of the above examples were replaced was prepared. This modified machine is placed in an environment room controlled at a temperature of 27 ° C and a humidity of 65%, and outputs images continuously under the conditions of 600 x 600 dpi, process speed: A3 output 35 sheets / min, and the next output image is evaluated. did. In addition, the next output image was evaluated and in-flight observation was performed after the test. The results are shown in Table 2.

(Evaluation of fine line image quality)
In order to confirm the discontinuity, fading, and disturbance of the thin line, a line having a thickness of 0.2 mm is output vertically (vertically), horizontally (horizontal), and obliquely 45 at an output of 1200 × 2400 dpi (dpi: number of dots per inch). This was output in each direction, and this was used as a test output for fine line image quality confirmation.
After the test output for fine line image quality confirmation is output at the beginning of the test (10th sheet after 10 sheets are output), 10000 continuous highlight images with a density of 15% are output on the entire surface of the A3 sheet. The test output for checking the fine line image quality was output again. The test image output at the initial stage of the test is “initial fine line image quality”, and the test image output after continuous output of 10,000 sheets is “maintainability of the fine line image quality”, and each fine line is magnified 4 times (for example, peak / anastigmat / loupe 4). X) and the like, and in accordance with the following evaluation criteria, line interruption, fading, and disturbance were confirmed.
-Evaluation criteria-
A: Fine line image quality is excellent.
○: Some variation in density is observed in the line, but it is at a level where there is no problem in practical use even in the use of advanced graphic images.
Δ: A level where there is a slight break in the middle of the line or a slight amount of toner scattered around the line, but does not interfere with character discrimination.
There is no problem when using text documents that do not require high-quality images.
X: Line breakage and toner scattering are remarkable, and this is a level that causes a problem in actual use, which also hinders character discrimination.

(Evaluation of image density stability)
Except that the test output image was changed to a solid image with a 100% image density of 5 × 5 cm at the center of the paper at 600 × 600 dpi output, the stability evaluation of the image density was performed in the same manner as for the fine line image quality confirmation. It was. The test output of the solid image output initially is “initial image density”, the test image of the solid image output after continuous output of 10 million sheets is “time-lapse image density”, and each solid image is measured by an image densitometer (for example, X− Image density was measured using Rite (X-Rite 404), and evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: “Time-lapse image density” is 97% or more with respect to “Initial image density”.
○: “Time-lapse image density” is 94% or more and less than 97% with respect to “initial image density”.
Δ: “Time-lapse image density” is 90% or more and less than 94% with respect to “initial image density”.
X: The “time-lapse image density” is less than 90% with respect to the “initial image density”.

(Evaluation of image density uniformity)
The test output image was changed to a highlight image with an image density of 30% at 5 × 5 cm at the center of the paper and at each of the four corners of the paper in 600 × 600 dpi output. Concentration stability was evaluated. The test output of the highlight image output in the initial stage was “initial image uniformity”, and the test image of the solid image output after continuous output of 10 million sheets was defined as “time-lapse image uniformity”. The density of the highlight image patch in each test image is measured, and whether the density of the remaining highlight image patch varies with respect to the highlight image patch with the highest density is based on the following evaluation criteria. And evaluated. The image density of the highlight image was measured using an image densitometer (for example, X-Rite 404 manufactured by X-Rite). The evaluation criteria are as follows.
-Evaluation criteria-
A: Image density fluctuation is 97% or more.
○: Image density variation is 94% or more and less than 97%.
Δ: Image density variation is 90% or more and less than 94%.
X: Image density variation is less than 90%.

  From the above results, it can be seen that in this example, compared to the comparative example, there was no “x” evaluation for any of the fine line image quality, image density stability, and image density uniformity, and good results were obtained. .

1Y, 1M, 1C, 1K, 107 photoconductor (image carrier)
2Y, 2M, 2C, 2K, 108 Charging roller 3Y, 3M, 3C, 3K Laser beam 3, 110 Exposure device 4Y, 4M, 4C, 4K, 111 Developing device (developing means)
5Y, 5M, 5C, 5K Primary transfer rollers 6Y, 6M, 6C, 6K, 113 Photoconductor cleaning device (cleaning means)
8Y, 8M, 8C, 8K Developer cartridge 10Y, 10M, 10C, 10K Unit 20 Intermediate transfer belt 22 Drive roller 24 Support roller 26 Secondary transfer roller (transfer means)
28, 115 Fixing device (fixing means)
30 Intermediate transfer member cleaning device 112 Transfer device 116 Mounting rail 117 Opening 118 for static elimination exposure Opening 200 for exposure Process cartridge,
P, 300 Recording paper (transfer object)

Claims (6)

Toner containing at least toner particles and an external additive having a number average particle diameter of 100 nm to 800 nm;
A carrier having a shape factor SF2 of 100 or more and 120 or less;
Particles composed of a higher fatty acid having 12 to 22 carbon atoms ;
Have a content of particles composed include the higher fatty acid for the entire electrostatic latent image developing developer is 1 wt% or less than 0.08 wt%, an electrostatic developer for developing.   The developer for electrostatic charge development according to claim 1, wherein a melting temperature of particles composed of the higher fatty acid is 40 ° C. or higher and 80 ° C. or lower.   3. The developer for electrostatic charge development according to claim 1, wherein the number average particle diameter of the particles composed of the higher fatty acid is 1 μm or more and 15 μm or less. Containing the developer for electrostatic charge development according to any one of claims 1 to 3,
A developer cartridge that is detachable from the image forming apparatus. Development in which the developer for electrostatic charge development according to any one of claims 1 to 3 is accommodated and an electrostatic charge image formed on an image carrier is developed as a toner image by the developer for electrostatic charge development. With means,
A process cartridge that is detachable from the image forming apparatus. An image carrier,
Charging means for charging the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
4. The electrostatic charge developing developer according to claim 1 is accommodated, and the electrostatic charge image formed on the image carrier is developed as a toner image by the electrostatic charge developing developer. Developing means,
Transfer means for transferring the toner image formed on the image carrier onto a transfer target;
Fixing means for fixing the toner image transferred onto the transfer target;
An image forming apparatus.