JP2017191230A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously form images with high picture qualities while suppressing wear of a photoreceptor, contamination of the photoreceptor and contamination of a charging device in continuous printing.SOLUTION: In an initial state, a developer comprising at least a toner is substantially accommodated in an accommodation part of a developing device 11. Toner particles in the toner include inorganic particles and resin particles as an external additive. The resin particles have a number average primary particle diameter of 70 nm or more and 200 nm or less. A blocking rate of the resin particles after pressurization at a temperature of 160°C and at a pressure of 0.1 kgf/mmfor 5 minutes is 20 mass% or more and 45 mass% or less measured by a mesh having a sieve opening of 75 μm. An isolation rate of the inorganic particles in a dispersion liquid of the toner, measured on the dispersion liquid of the toner in a state of being subjected to an ultrasonic treatment for 5 minutes, is 5% or less in terms of a peak intensity ratio in a fluorescent X-ray spectrum, and an isolation rate of the resin particles in a dispersion liquid of the toner is 10% or more and 30% or less in terms of a peak area ratio in a GC(Gas Chromatography)/MS(Mass Spectrometry) method.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus and an image forming method.

  Patent Document 1 discloses an image forming apparatus including a photoreceptor, a charging device (charging roller), an exposure device, and a developing device. In the image forming apparatus described in Patent Document 1, a lubricant is supplied to the surface of the photoreceptor using a specific solid lubricant and a fur brush.

JP 2006-91047 A

  However, in the continuous printing by the image forming apparatus, it is considered that the technique disclosed in Patent Document 1 is not sufficient for suitably suppressing the abrasion of the photoreceptor, the contamination of the photoreceptor, and the contamination of the charging device. It is done. For example, the image forming apparatus described in Patent Document 1 requires a specific solid lubricant and fur brush, which makes it difficult to reduce the cost.

  The present invention has been made in view of the above circumstances, and continuously forms high-quality images while suppressing photoconductor wear, photoconductor contamination, and charging device contamination in continuous printing. An object of the present invention is to provide an image forming apparatus and an image forming method.

An image forming apparatus according to the present invention includes an image carrier, a contact charging type charging device, an exposure device, and a developing device. The charging device is configured to charge the surface of the image carrier while being in contact with the surface of the image carrier. The exposure apparatus is configured to form an electrostatic latent image on the surface of the image carrier by exposing the surface of the charged image carrier. The developing device includes a storage unit that stores a developer for developing the electrostatic latent image. In an initial state, the storage portion substantially stores a developer containing at least toner. The toner includes a plurality of toner particles including toner mother particles and an external additive attached to the surface of the toner mother particles. The toner particles include inorganic particles and resin particles as the external additive. The number average primary particle diameter of the resin particles is 70 nm or more and 200 nm or less. The blocking rate of the resin particles after pressing for 5 minutes at a temperature of 160 ° C. and a pressure of 0.1 kgf / mm ² is 20% by mass or more and 45% by mass or less as measured with a mesh having an opening of 75 μm. The liberation rate of the inorganic particles in the toner dispersion measured in the toner dispersion after sonication for 5 minutes is 5% or less in terms of the peak intensity ratio of the fluorescent X-ray spectrum. The liberation rate of the resin particles in the toner dispersion is 10% or more and 30% or less as a peak area ratio of the GC / MS mass spectrum.

The image forming method according to the present invention includes a charging step, an exposure step, and a development step. In the charging step, the surface of the image carrier is charged while contacting the surface of the image carrier. In the exposure step, an electrostatic latent image is formed on the surface of the image carrier by exposing the surface of the charged image carrier. In the developing step, toner in a housing portion of a developing device is supplied to the image carrier, and the electrostatic latent image is developed with the toner. The toner includes a plurality of toner particles including toner mother particles and an external additive attached to the surface of the toner mother particles. The toner particles include inorganic particles and resin particles as the external additive. The number average primary particle diameter of the resin particles is 70 nm or more and 200 nm or less. The blocking rate of the resin particles after pressing for 5 minutes at a temperature of 160 ° C. and a pressure of 0.1 kgf / mm ² is 20% or more and 45% or less as measured with a mesh having an opening of 75 μm. The liberation rate of the inorganic particles in the toner dispersion, which is measured for a toner dispersion in a state where ultrasonic treatment is performed for 5 minutes, is 5% or less as a peak intensity ratio by fluorescent X-ray analysis. The liberation rate of the resin particles in the toner dispersion is 10% or more and 30% or less as a peak area ratio according to the GC / MS method.

  According to the present invention, in continuous printing, an image forming apparatus and an image forming apparatus capable of continuously forming a high-quality image while suppressing photoconductor abrasion, photoconductor contamination, and charging device contamination. It becomes possible to provide a method.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the image development apparatus of the image forming apparatus shown in FIG. FIG. 3 is a diagram illustrating an example of a surface structure of toner particles used in an image forming apparatus according to an embodiment of the present invention. FIG. 5 is a diagram for explaining the operation and effect of the image forming apparatus according to the embodiment of the present invention.

  An embodiment of the present invention will be described. Note that the evaluation results (values indicating shape, physical properties, etc.) regarding the powder (more specifically, toner base particles, external additives, toner, carrier, etc.) are average values from the powder unless otherwise specified. This is the number average of the values measured for each of the average particles by selecting a significant number of such particles.

The number average particle diameter of the powder is the number average value of the equivalent circle diameter of primary particles (diameter of a circle having the same area as the projected area of the particles) measured using a microscope unless otherwise specified. . Moreover, the measured value of the volume median diameter (D ₅₀ ) of the powder is measured using a laser diffraction / scattering particle size distribution measuring device (“LA-750” manufactured by Horiba, Ltd.) unless otherwise specified. It is the value. Moreover, the softening point (Tm) is a value measured using a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation) unless otherwise specified. In the S curve (horizontal axis: temperature, vertical axis: stroke) measured with the Koka type flow tester, the temperature that becomes "(baseline stroke value + maximum stroke value) / 2" is Tm (softening point). Equivalent to. Further, the measured value of the acid value is a value measured according to “JIS (Japanese Industrial Standard) K0070-1992” unless otherwise specified.

  Hereinafter, a compound and its derivatives may be generically named by adding “system” after the compound name. When the name of a polymer is expressed by adding “system” after the compound name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof. Acrylic and methacrylic are sometimes collectively referred to as “(meth) acrylic”. Further, acrylonitrile and methacrylonitrile may be collectively referred to as “(meth) acrylonitrile”. Further, the silica particles mean dry silica particles unless otherwise specified.

  Hereinafter, an example of the image forming apparatus (image forming apparatus 100) according to the present embodiment will be described with reference to FIGS.

  The image forming apparatus 100 is a tandem electrophotographic apparatus. As illustrated in FIG. 1, the image forming apparatus 100 includes developing devices 11 a to 11 d, photosensitive drums 12 a to 12 d, a transfer device 10, a fixing device 17, and a cleaning device 18. The transfer device 10 includes a transfer belt 13, a drive roller 14a, a driven roller 14b, a tension roller 14c, primary transfer rollers 15a to 15d, and a secondary transfer roller 16. The transfer belt 13 is stretched around a driving roller 14a, a driven roller 14b, and a tension roller 14c. The transfer belt 13 is driven by a driving roller 14a and rotates in a direction indicated by an arrow in FIG. The fixing device 17 is, for example, a nip fixing type fixing device including a heating roller and a pressure roller. The cleaning device 18 removes the toner remaining on the transfer belt 13. When an image is formed using the image forming apparatus 100, for example, a two-component developer is set in each of the developing devices 11a to 11d. The image forming apparatus 100 includes a control unit 20 that electronically controls the operation of the image forming apparatus 100 based on outputs from various sensors. The control unit 20 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), and a storage device that stores a program and rewritable data. The user can give an instruction (electric signal) to the control unit 20 through an input unit (for example, a keyboard, a mouse, or a touch panel) (not shown).

  The two-component developer includes a toner and a carrier. The toner and the carrier are each a powder composed of a large number of particles. The toner includes a plurality of toner particles having the configuration described below. The carrier includes a plurality of carrier particles having the configuration described below. The toner contained in the two-component developer can be used as, for example, a positively chargeable toner. The positively chargeable toner is positively charged by friction with the carrier. Carrier particles contained in the carrier have magnetism. In order to impart magnetism to the carrier particles, at least a part of the carrier particles may be formed of a magnetic material (for example, a ferromagnetic material such as ferrite), or the carrier particles may be formed of a resin in which the magnetic particles are dispersed. You may form at least one part.

  The image forming apparatus 100 forms an electrostatic latent image on each surface layer portion (photosensitive layer) of the photoconductive drums 12a to 12d based on the image data. Next, the formed electrostatic latent image is developed using a two-component developer (toner and carrier) set in each of the developing devices 11a to 11d. Each of the developing devices 11a to 11d has a configuration shown in FIG. Hereinafter, when it is not necessary to distinguish (when common properties are described), each of the developing devices 11a to 11d is described as the developing device 11, and each of the photosensitive drums 12a to 12d is described as the photosensitive drum 12. To do. FIG. 2 is a cross-sectional view showing the internal configuration of the developing device 11.

  As shown in FIG. 2, the image forming apparatus 100 includes a charging device for uniformly charging the photosensitive layer of the photosensitive drum 12 with static electricity. The charging device includes a charging member 21 (for example, a charging roller) that contacts the surface F of the photosensitive drum 12 and is configured to charge the photosensitive layer by a contact charging method. The charged charging member 21 (for example, a member charged by applying a DC voltage or an AC superimposed DC voltage obtained by superimposing an AC voltage on the DC voltage) comes into contact with the photosensitive layer, thereby charging the photosensitive layer. To do. The charging member 21 is not limited to a roller and is optional, and may be a brush or a blade. The charging member 21 may be pressed against the surface F of the photosensitive drum 12 by a biasing force of a spring, for example. Further, as shown in FIG. 1, the image forming apparatus 100 includes an exposure device 22 for forming an electrostatic latent image on each photosensitive layer of the photosensitive drums 12a to 12d. The exposure device 22 includes, for example, an LED (light emitting diode) head as a light source. The exposure device 22 is configured to selectively irradiate each photosensitive layer of the photosensitive drums 12a to 12d with, for example, light emitted from an LED head based on the image data. When the exposure device 22 exposes the charged photosensitive layer, an electrostatic latent image is formed on the photosensitive layer. Further, as shown in FIG. 2, the image forming apparatus 100 includes a cleaning blade 23 (for example, a rubber plate) for removing a substance (attachment) attached to the surface F of the photosensitive drum 12. The cleaning blade 23 is pressed against the surface F of the photosensitive drum 12 by a biasing force of a spring, for example, and is configured to scrape off deposits on the photosensitive drum 12. As the photosensitive drum 12 rotates, the cleaning blade 23 slides relative to the surface F of the photosensitive drum 12.

  As shown in FIG. 2, the developing device 11 includes a developing roller 111, a magnetic roller 112, a regulating blade 112 d, a first stirring shaft 113, and a second stirring shaft 114. Further, the developing device 11 includes a transport unit R1 and storage units R2 and R3. The transport unit R1 accommodates the developing roller 111 and the magnetic roller 112. The accommodating portion R2 accommodates the first stirring shaft 113, and the accommodating portion R3 accommodates the second stirring shaft 114. The developing roller 111 is disposed in the vicinity of the photosensitive drum 12. In the example shown in FIG. 2, a gap is provided between the developing roller 111 and the photosensitive drum 12.

  The developing device 11 is configured to develop the electrostatic latent image with toner. In the image forming apparatus 100 in the initial state (unused state), the storage units R2 and R3 each store a two-component developer including toner (initial toner) and a carrier. However, the toner (initial toner) and the carrier may be automatically supplied to the accommodating portions R2 and R3 of the developing device 11 by an initial setting (installation operation) when starting to use the image forming apparatus 100.

  The developing device 11 is provided with a replenishment toner container 115. The supply toner container 115 (toner supply unit) is configured to supply supply toner into the developing device 11. The replenishment toner container 115 stores replenishment toner. The replenishment toner in the replenishment toner container 115 is supplied to the developing device 11 (specifically, the accommodating portion R3). The replenishment toner container 115 includes a replenishment amount adjusting member 115a. The supply amount of toner (the amount of toner supplied from the supply toner container 115 to the developing device 11) can be controlled by the supply amount adjusting member 115a. The replenishment amount adjusting member 115 a is configured by, for example, a screw shaft whose rotation operation is controlled by the control unit 20.

  The initial toner and the replenishing toner may be the same toner or different toners. However, in order to stably form a suitable image, the initial toner and the replenishing toner are preferably the same toner. Note that the fact that two or more toners are the same means that there is substantially no difference in properties between the toners so that the toners are compatible.

  Each of the first stirring shaft 113 and the second stirring shaft 114 has a spiral stirring blade. The first agitation shaft 113 and the second agitation shaft 114 convey the developer in opposite directions while agitating the developer in the developing device 11 (specifically, the accommodating portions R2 and R3). By stirring the developer, the toner in the developer is triboelectrically charged, and the carrier in the developer carries the toner.

  The magnetic roller 112 includes a magnet roll and a sleeve. The sleeve is a nonmagnetic cylinder (for example, an aluminum pipe). The shaft of the magnet roll and the sleeve are connected via a flange so that the sleeve can rotate around the non-rotating magnet roll. The magnetic roller 112 is driven by, for example, a motor (not shown) and rotates in the direction of the arrow in FIG.

  The magnet roll of the magnetic roller 112 has a predetermined magnetic pole (for example, a magnetic pole based on a permanent magnet). Hereinafter, among the magnetic poles of the magnet roll of the magnetic roller 112, the magnetic pole facing the first stirring shaft 113 is the upper pole 112a, the magnetic pole facing the developing roller 111 is the main pole 112b, and the magnetic pole facing the regulating blade 112d. Each of them is described as a regulation electrode 112c.

  While rotating the sleeve in the direction of the arrow in FIG. 2, the magnetic roller 112 attracts the carrier in the accommodating portion R2 by the magnetic force of the pumping upper pole 112a, and carries the developer (carrier and toner) on the surface of the sleeve. The developer is carried on the surface of the magnetic roller 112 with the toner carried on the surface of the carrier. As a result, a magnetic brush by the carrier is formed on the surface of the magnetic roller 112. The magnetic brush is a carrier particle cluster that is raised on the surface of the magnetic roller 112. Toner adheres to the surface of the carrier particles connected in spikes. The thickness (ear height) of the magnetic brush is regulated to a predetermined thickness by the regulating blade 112d. The regulation blade 112d is a plate-like magnetic member that can be magnetized by the magnetic force of the regulation pole 112c, for example. The developing roller 111 and the magnetic roller 112 are arranged at an interval such that the magnetic brush on the magnetic roller 112 is in contact with the developing roller 111. Further, the magnetic force of the main pole 112 b acts so as to supply only the toner of the developer (toner and carrier) carried on the surface of the magnetic roller 112 to the developing roller 111.

  The developing roller 111 includes a magnet roll and a developing sleeve. The developing sleeve is a nonmagnetic cylinder (for example, an aluminum pipe). The magnet roll is located in the developing sleeve (in the cylinder), and the developing sleeve is located in the surface layer portion of the developing roller 111. The shaft of the magnet roll and the developing sleeve are connected via a flange so that the developing sleeve can rotate around the non-rotating magnet roll. The developing roller 111 is driven by, for example, a motor (not shown) and rotates in the direction of the arrow in FIG.

  As the photoconductor drum 12, for example, an organic photoconductor (OPC) drum is preferably used. The photosensitive drum 12 has a cylindrical outer shape. The photosensitive drum 12 includes a metal cylinder (for example, an aluminum pipe) as a core material, and a single-layer type photosensitive layer or a multilayer type photosensitive material containing a charge generating agent and a charge transport agent on the outside of the core material. Further provided are layers (eg, an undercoat layer, a charge generation layer, and a charge transport layer). A protective layer for protecting the photosensitive layer may be provided on the surface of the photosensitive layer. The photosensitive drum 12 is supported by, for example, a housing of the image forming apparatus 100 in a rotatable manner, and is driven by, for example, a motor (not shown) to rotate in the direction of the arrow in FIG.

  In order to supply the toner in the developer carried on the magnetic roller 112 to the photosensitive drum 12, for example, by applying a bias (voltage) to at least one of the developing roller 111 and the magnetic roller 112, the surface potentials of both are developed. A potential difference is generated between the two. Due to this potential difference, the toner in the developer carried on the magnetic roller 112 moves to the developing roller 111 and is carried on the surface of the developing roller 111. Specifically, the developer carried on the surface of the magnetic roller 112 (particularly, carried on the surface of the carrier) by rotating the sleeve of the developing roller 111 and the sleeve of the magnetic roller 112 in the direction of the arrow in FIG. Toner) and the developing roller 111 rub against each other. The toner in the developer carried on the surface of the magnetic roller 112 is electrically attracted to the developing roller 111. As a result, a toner layer is formed on the surface of the developing roller 111.

  Furthermore, by applying a bias (voltage) to at least one of the developing roller 111 and the photosensitive drum 12, a potential difference is generated between the surface potentials of the two. This potential difference makes it easier for the toner carried on the developing roller 111 to move to the photosensitive drum 12. The toner carried on the developing roller 111 is electrically attracted to the exposed portion of the electrostatic latent image formed on the photosensitive drum 12 (for example, the portion whose potential is lower than the surroundings due to exposure), and the photosensitive drum. Fly to 12 As a result, a toner image is formed on the surface F of the photosensitive drum 12.

  The description will be continued with reference to FIG. As described above, in the image forming apparatus 100, the developing devices 11a, 11b, 11c, and 11d respectively develop the electrostatic latent images formed on the photosensitive drums 12a, 12b, 12c, and 12d (each image carrier). . The image forming apparatus 100 forms a toner image on each photosensitive drum 12, and then applies a bias (voltage) to each of the primary transfer rollers 15a to 15d to attach the toner (which adheres to each of the photosensitive drums 12a to 12d). The toner image is transferred (primary transfer) to the transfer belt 13 (intermediate transfer member). Further, by applying a bias (voltage) to the secondary transfer roller 16, the toner image on the transfer belt 13 is transferred (secondary transfer) to the transported recording medium P (transfer object). Thereafter, the fixing device 17 heats the toner to fix the toner on the recording medium P. Thereby, an image is formed on the recording medium P. Note that the toner remaining on the photosensitive drum 12 after the transfer process is removed together with other deposits on the photosensitive drum 12 by cleaning. In the cleaning process, the surface F of the photosensitive drum 12 is rubbed with the edge portion of the cleaning blade 23 to scrape and remove the deposits on the photosensitive drum 12.

  The image forming apparatus 100 includes a plurality of photosensitive drums 12a to 12d. For this reason, the image forming apparatus 100 sequentially transfers the toner images formed on each of the plurality of photosensitive drums 12a to 12d to the transfer belt 13 in the primary transfer step, thereby transferring a plurality of toner images onto the transfer belt 13. Different types of toner images (eg, toner images of different colors) can be superimposed. In the image forming apparatus 100, the toner images superimposed on the transfer belt 13 can be collectively transferred to the recording medium P in the secondary transfer process. For example, a full color image can be formed by superposing four color toner images of black, yellow, magenta, and cyan. As the recording medium P, for example, printing paper can be used.

  The image forming apparatus 100 is a touchdown image forming apparatus configured to develop an electrostatic latent image by the following touchdown development method.

(Touch-down development method)
The image forming method includes forming a magnetic brush, forming a toner layer, forming an electrostatic latent image, and forming a toner image. In the formation of the magnetic brush, a two-component developer containing toner and carrier is carried on the surface of a magnetic carrier (for example, the magnetic roller 112 shown in FIG. 2) in a state where the toner is carried on the surface of the carrier. By carrying the two-component developer on the magnetic carrier, a magnetic brush by the carrier is formed on the surface of the magnetic carrier. In the formation of the toner layer, the toner of the two-component developer carried on the surface of the magnetic carrier is moved to a toner carrier (for example, the developing roller 111 shown in FIG. 2) facing the magnetic carrier, A toner layer is formed on the surface of the toner carrier. In forming an electrostatic latent image, an electrostatic latent image is formed on the surface of an image carrier (for example, the photosensitive drum 12 shown in FIG. 2) facing the toner carrier. In the formation of the toner image, the toner in the toner layer formed on the surface of the toner carrier is caused to fly toward the image carrier to form a toner image on the surface of the image carrier.

  The image forming apparatus according to the present embodiment has the following configuration (hereinafter referred to as a basic configuration).

(Basic configuration of image forming apparatus)
An image carrier (for example, the photosensitive drum 12 shown in FIG. 2), a contact charging type charging device (for example, a charging device including the charging member 21 shown in FIG. 2), and an exposure device (for example, FIG. 1). And the developing device (for example, the developing device 11 shown in FIG. 2). The charging device is configured to charge the surface of the image carrier while being in contact with the surface of the image carrier. The exposure apparatus is configured to form an electrostatic latent image on the surface of the image carrier by exposing the surface of the charged image carrier. The developing device includes a storage unit that stores a developer for developing the electrostatic latent image. In the initial state, the developer containing at least toner (initial toner) is substantially contained in the accommodating portion of the developing device. The toner includes a plurality of toner particles including toner mother particles and an external additive attached to the surface of the toner mother particles. The toner particles include inorganic particles and resin particles as external additives. The number average primary particle diameter of the resin particles is 70 nm or more and 200 nm or less. The blocking rate of the resin particles after pressing for 5 minutes at a temperature of 160 ° C. and a pressure of 0.1 kgf / mm ² is 20% by mass or more and 45% by mass or less as measured with a mesh having an opening of 75 μm. The liberation rate of the inorganic particles in the toner dispersion measured with respect to the above-mentioned toner dispersion after ultrasonic treatment for 5 minutes (hereinafter sometimes referred to as toner dispersion) The peak intensity ratio is 5% or less, and the liberation rate of the resin particles in the toner dispersion is 10% or more and 30% or less in the peak area ratio of the GC / MS mass spectrum. The number average primary particle diameter of the resin particles (external additive) is the number average value of the equivalent-circle diameters of the primary particles measured by observing the surface of the toner particles using a microscope (for example, SEM). is there. Moreover, each measuring method of a blocking rate and a release rate is the same method as the Example mentioned later, or its alternative method.

  The initial state means an unused state (for example, at the time of product sales). The initial toner is toner that is substantially housed in the housing portion of the developing device in the initial state. The initial toner includes not only the toner stored in the developing device storage unit in the initial state of the image forming apparatus, but also the initial setting (installation operation) at the start of use of the image forming apparatus. In addition, the toner to be charged automatically is also included. The initial toner is distinguished from the replenishing toner. The replenishment toner is toner that is replenished to the housing portion of the developing device after the start of use of the initial toner.

  Hereinafter, the blocking rate of resin particles, the release rate of inorganic particles, and the release rate of resin particles specified by the above basic configuration, respectively, omitting measurement conditions, etc., simply blocking rate of resin particles, release rate of inorganic particles And the liberation rate of the resin particles.

  FIG. 3 shows an example of the surface structure of the toner particles. The toner particles shown in FIG. 3 include toner base particles 30 and external additives (inorganic particles 31 and resin particles 32) attached to the surface of the toner base particles 30. The inorganic particles 31 may be silica particles, for example.

  In the toner having the above basic structure, the liberation rate of the inorganic particles (external additive) is 5% or less, the liberation rate of the resin particles (external additive) is 10% or more and 30% or less, and the resin particles (external additive) The number average primary particle diameter of the agent is 70 nm or more and 200 nm or less. With this configuration, it is possible to release the resin particles from the toner particles and store them on the edge of the cleaning blade prior to the removal of the inorganic particles. For example, as shown in FIG. 4, the resin particles 32 are accumulated on the edge portion E (tip portion) of the cleaning blade 23 on the surface F of the photosensitive drum 12, thereby removing the deposits on the photosensitive drum 12. It becomes possible to dam at the edge portion E of this. Due to the presence of an appropriate amount of resin particles 32 at the edge E of the cleaning blade 23, deposits (especially inorganic particles) on the photosensitive drum 12 cause the surface F of the photosensitive drum 12, the edge E of the cleaning blade 23, and the edge E. It becomes difficult to slip through. If the deposit on the photosensitive drum 12 passes between the surface F of the photosensitive drum 12 and the edge E of the cleaning blade 23, the charging member 21 (for example, a charging roller) is likely to be contaminated. Further, when the number average primary particle diameter of the resin particles (external additive) is too small, the resin particles do not sufficiently function as a spacer between the toner particles, and the stress resistance of the toner tends to be insufficient. . On the other hand, if the number average primary particle diameter of the resin particles (external additive) is too large, the fluidity of the toner is deteriorated, or the resin particles accumulated on the edge of the cleaning blade (for example, the photoconductor). The photosensitive layer of the drum) is likely to be scraped off. The particle diameter of the resin particles can be adjusted based on, for example, polymerization conditions (particularly stirring conditions) during resin synthesis. In the toner having the above basic structure, for example, even when the number average primary particle diameter of the inorganic particles (external additive) is 5 nm or more and 50 nm or less, the slipping of the inorganic particles at the edge portion of the cleaning blade is preferably suppressed. It is thought that you can.

  In order to suppress the contamination of the charging device, the smaller the release rate of the inorganic particles (external additives), the better, and the lower limit value is not limited. The liberation rate of the inorganic particles may be 0%. However, from the viewpoint of productivity, the liberation rate of the inorganic particles is preferably 1% or more. On the other hand, when the liberation rate of the resin particles (external additive) is too high, the charging device is easily contaminated. The liberation rate of the external additive (inorganic particles or resin particles) can be adjusted by changing external addition conditions (for example, external addition time).

  If the blocking rate of the resin particles (external additive) exceeds 45% by mass, photoconductor contamination (external additive adhesion to the photosensitive drum) and carrier contamination (external additive adhesion to the carrier) are likely to occur. Tend to be. Moreover, the blocking rate of the resin particles tends to decrease as the hardness of the resin particles (specifically, difficulty in thermal compression) increases. In order to make the blocking rate of the resin particles 45% by mass or less, it is considered that the hardness of the resin particles needs to be very high. The inventor succeeded in reducing the blocking rate of the resin particles to 45% by mass or less by using a high-purity crosslinking agent. For example, when divinylbenzene is used as a crosslinking agent, divinylbenzene having a purity (mass fraction) of about 50% is generally used, but resin particles can be obtained by using divinylbenzene having a purity of 80%. Successfully achieved a blocking rate of 45% by mass or less.

  However, if the hardness of the resin particles (external additive) is too high, the blocking rate of the resin particles is considered to be less than 20% by mass. When the blocking rate of the resin particles is less than 20% by mass, the photosensitive member (for example, the photosensitive layer of the photosensitive drum) is easily scraped by the resin particles accumulated at the edge of the cleaning blade, and the life of the photosensitive drum is shortened. Become. The blocking rate of the resin particles can be adjusted, for example, by changing the amount of the crosslinking agent added during resin synthesis.

  Note that the image forming apparatus having the above-described basic configuration is not limited to the touch-down image forming apparatus, and it is considered that the above-described basic configuration provides the above effects.

  In order to make the liberation rate of each of the inorganic particles and the resin particles within the range defined by the above basic configuration, the number average primary particle diameter of the resin particles (external additive) is set to the inorganic particles (external additive). It is preferable that the number average primary particle diameter is larger.

  In order to make the liberation rate of each of the inorganic particles and the resin particles within the range defined by the above basic configuration, the inorganic particles and the resin particles are laminated in order of the inorganic particles and the resin particles from the surface of the toner base particles. It preferably has a structure. Hereinafter, an example of inorganic particles and resin particles having the above-described laminated structure (lower layer: inorganic particles, upper layer: resin particles) on the surface of the toner base particles will be described with reference to FIG.

  Inorganic particles 31 (for example, silica particles) and resin particles 32 are present on the surface of the toner base particles 30 shown in FIG. The inorganic particles 31 and the resin particles 32 have a laminated structure in which the inorganic particles 31 and the resin particles 32 are laminated in this order from the toner base particle 30 side. That is, the inorganic particles 31 are located closer to the toner base particles 30 than the resin particles 32. The inorganic particles 31 are attached to the surface of the toner base particles 30. The resin particles 32 are attached to the surface of the inorganic particles 31 (however, the surface of the toner base particles 30 in the region where the inorganic particles 31 are not present in the surface region of the toner base particles 30).

  The toner particles contained in the initial toner may be toner particles in which the toner base particles do not have a shell layer (hereinafter referred to as non-capsule toner particles), or toner particles in which the toner base particles have a shell layer (hereinafter referred to as non-capsule toner particles). May be described as capsule toner particles). Capsule toner particles can be produced by forming a shell layer on the surface of toner base particles (toner core) of non-capsule toner particles. The shell layer may be substantially composed of only a thermosetting resin (for example, a “preferable thermosetting resin” described later), or substantially a thermoplastic resin (for example, a “preferable thermoplastic resin described later). ]) Or may contain both a thermoplastic resin and a thermosetting resin.

  Non-capsule toner particles can be produced, for example, by a pulverization method or an aggregation method. In these methods, the internal additive is easily dispersed well in the binder resin of the non-capsule toner particles.

  In an example of the pulverization method, first, a binder resin, a colorant, a charge control agent, and a release agent are mixed. Subsequently, the obtained mixture is melt-kneaded using a melt-kneading apparatus (for example, a single-screw or twin-screw extruder). Subsequently, the obtained melt-kneaded product is pulverized and classified. Thereby, toner mother particles are obtained. When the pulverization method is used, the toner base particles can often be produced more easily than when the aggregation method is used.

  In an example of the aggregation method, first, these fine particles are aggregated in an aqueous medium containing fine particles of a binder resin, a release agent, a charge control agent, and a colorant until a desired particle size is obtained. Thereby, aggregated particles containing a binder resin, a release agent, a charge control agent, and a colorant are formed. Subsequently, the obtained aggregated particles are heated to unite the components contained in the aggregated particles. Thereby, toner mother particles having a desired particle diameter are obtained.

  When producing the capsule toner particles, the method for forming the shell layer is arbitrary. For example, the shell layer may be formed using any one of an in-situ polymerization method, a submerged cured coating method, and a coacervation method.

  Preferred examples of the resin constituting each of the toner particles and carrier particles are shown below.

<Preferable thermoplastic resin>
Suitable examples of thermoplastic resins include styrene resins, acrylic resins (more specifically, acrylic ester polymers or methacrylic ester polymers), olefin resins (more specifically, polyethylene). Resin or polypropylene resin), vinyl chloride resin, polyvinyl alcohol, vinyl ether resin, N-vinyl resin, polyester resin, polyamide resin, or urethane resin. Further, a copolymer of each of these resins, that is, a copolymer in which an arbitrary repeating unit is introduced into the resin (specifically, a styrene-acrylic acid resin or a styrene-butadiene resin) is used. May be.

  The thermoplastic resin can be obtained by addition polymerization, copolymerization, or condensation polymerization of one or more thermoplastic monomers. The thermoplastic monomer is a monomer that becomes a thermoplastic resin by homopolymerization (more specifically, an acrylic acid monomer or a styrene monomer), or a monomer that becomes a thermoplastic resin by condensation polymerization (for example, by condensation polymerization). A combination of a polyhydric alcohol and a polyhydric carboxylic acid to be a polyester resin.

  The styrene-acrylic acid resin is a copolymer of one or more styrene monomers and one or more acrylic monomers. In order to synthesize a styrene-acrylic acid resin, for example, a styrene monomer and an acrylic acid monomer as shown below can be suitably used.

  Preferable examples of the styrene monomer include styrene, alkyl styrene (more specifically, α-methyl styrene, p-ethyl styrene, 4-tert-butyl styrene, etc.), p-hydroxy styrene, m-hydroxy styrene. , Vinyl toluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, or p-chlorostyrene.

  Preferable examples of the acrylic acid monomer include (meth) acrylic acid, (meth) acrylonitrile, (meth) acrylic acid alkyl ester, or (meth) acrylic acid hydroxyalkyl ester. Suitable examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and (meth) acrylic. Examples include n-butyl acid, iso-butyl (meth) acrylate, or 2-ethylhexyl (meth) acrylate. Suitable examples of the (meth) acrylic acid hydroxyalkyl ester include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, or (meth) acrylic. The acid 4-hydroxybutyl is mentioned.

  The polyester resin is obtained by polycondensation of one or more polyhydric alcohols and one or more polyhydric carboxylic acids. As the alcohol for synthesizing the polyester resin, for example, dihydric alcohols (more specifically, diols or bisphenols) as shown below or trihydric or higher alcohols can be suitably used. As the carboxylic acid for synthesizing the polyester resin, for example, divalent carboxylic acids or trivalent or higher carboxylic acids as shown below can be suitably used.

  Suitable examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, Examples include 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, di1,2-propanediol, polyethylene glycol, poly1,2-propanediol, or polytetramethylene glycol.

  Preferable examples of the bisphenol include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, or bisphenol A propylene oxide adduct.

  Preferable examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane. Triol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, or 1,3,5- Trihydroxymethylbenzene is mentioned.

  As preferable examples of the divalent carboxylic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, malonic acid Succinic acid, alkyl succinic acid (more specifically, n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, etc.), or alkenyl succinic acid (more specific Specifically, n-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid, or isododecenyl succinic acid, etc.) may be mentioned.

  Preferred examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) Examples include methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or empole trimer acid.

<Preferable thermosetting resin>
Preferred examples of the thermosetting resin include melamine resin, urea resin, sulfonamide resin, glyoxal resin, guanamine resin, aniline resin, polyimide resin (more specifically, maleimide polymer or bismuth resin). Maleimide polymer, etc.), xylene-based resin, or epoxy resin.

The thermosetting resin can be obtained by crosslinking (polymerizing) one or more thermosetting monomers. Moreover, a thermosetting resin can also be synthesize | combined with a thermoplastic monomer by using a crosslinking agent. The thermosetting monomer is a monomer having crosslinkability. For example, when monomers of the same kind are three-dimensionally connected via “—CH ₂ —” to become a thermosetting resin, the monomer corresponds to a “thermosetting monomer”.

  Preferable examples of the thermosetting monomer include methylol melamine, melamine, methylolated urea (more specifically, dimethylol dihydroxyethylene urea), urea, benzoguanamine, acetoguanamine, or spiroguanamine.

  Next, preferred examples of the configuration of each of the non-capsule toner particles and the carrier particles will be described.

[Toner mother particles]
The toner base particles contain a binder resin. The toner base particles may contain an internal additive (for example, a colorant, a release agent, a charge control agent, and a magnetic powder).

(Binder resin)
In the toner base particles, generally, the binder resin occupies most of the components (for example, 85% by mass or more). For this reason, it is considered that the properties of the binder resin greatly affect the overall properties of the toner base particles. In order to achieve both the heat-resistant storage stability and the low-temperature fixability of the toner, the toner base particles preferably contain the above-mentioned “suitable thermoplastic resin” as the binder resin. The polyester resin and the styrene-acrylic acid are preferable. It is particularly preferable to contain at least one of the resin. In order to improve the charging stability of the toner, it is particularly preferable that the toner base particles contain a polyester resin having an acid value of 5 mgKOH / g or more and 20 mgKOH / g or less as a binder resin.

(Coloring agent)
The toner base particles may contain a colorant. As the colorant, a known pigment or dye can be used according to the color of the toner. In order to form a high-quality image using toner, the amount of the colorant is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin.

  The toner base particles may contain a black colorant. An example of a black colorant is carbon black. The black colorant may be a colorant that is toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

  The toner base particles may contain a color colorant such as a yellow colorant, a magenta colorant, or a cyan colorant.

  As the yellow colorant, for example, one or more compounds selected from the group consisting of condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds can be used. Examples of the yellow colorant include C.I. I. Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155 168, 174, 175, 176, 180, 181, 191, or 194), naphthol yellow S, Hansa yellow G, or C.I. I. Vat yellow can be preferably used.

  The magenta colorant is, for example, selected from the group consisting of condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. One or more compounds can be used. Examples of the magenta colorant include C.I. I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 169, 177 184, 185, 202, 206, 220, 221 or 254) can be preferably used.

  As the cyan colorant, for example, one or more compounds selected from the group consisting of a copper phthalocyanine compound, an anthraquinone compound, and a basic dye lake compound can be used. Examples of cyan colorants include C.I. I. Pigment blue (1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, or 66), phthalocyanine blue, C.I. I. Bat Blue, or C.I. I. Acid blue can be preferably used.

(Release agent)
The toner base particles may contain a release agent. The release agent is used, for example, for the purpose of improving the fixing property or offset resistance of the toner. In order to improve the fixing property or offset resistance of the toner, the amount of the release agent is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin.

  Examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, or aliphatic hydrocarbon wax such as Fischer-Tropsch wax; oxidized polyethylene wax or a block thereof Oxides of aliphatic hydrocarbon waxes such as copolymers; plant waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, or rice wax; animal properties such as beeswax, lanolin, or whale wax Waxes; mineral waxes such as ozokerite, ceresin, or petrolatum; waxes based on fatty acid esters such as montanate ester wax or castor wax; fats such as deoxidized carnauba wax The wax portion of the ester or the whole was deoxygenated can be suitably used. One type of release agent may be used alone, or multiple types of release agents may be used in combination.

(Charge control agent)
The toner base particles may contain a charge control agent. The charge control agent is used, for example, for the purpose of improving the charge stability or charge rising property of the toner. The charge rising characteristic of the toner is an index as to whether or not the toner can be charged to a predetermined charge level in a short time.

  By adding a positively chargeable charge control agent (more specifically, pyridine, nigrosine, quaternary ammonium salt, or the like) to the toner base particles, the cationicity of the toner base particles can be increased. However, if sufficient chargeability is ensured in the toner, it is not necessary to add a charge control agent to the toner base particles.

(Magnetic powder)
The toner base particles may contain magnetic powder. Examples of magnetic powder materials include ferromagnetic metals (more specifically, iron, cobalt, nickel, or alloys containing one or more of these metals), ferromagnetic metal oxides (more specifically, Ferrite, magnetite, chromium dioxide, or the like) or a material subjected to ferromagnetization treatment (more specifically, a carbon material or the like imparted with ferromagnetism by heat treatment) can be suitably used. In order to suppress elution of metal ions (for example, iron ions) from the magnetic powder, it is preferable to use the surface-treated magnetic particles as the magnetic powder. One type of magnetic powder may be used alone, or a plurality of types of magnetic powder may be used in combination.

[External additive]
An external additive (specifically, a powder containing a plurality of external additive particles) adheres to the surface of the toner base particles. Specifically, the toner particles include inorganic particles and resin particles as external additives. For example, the toner base particles (powder) and the external additive (powder) are stirred together, so that the external additive adheres (physically bonds) to the surface of the toner base particles with a physical force.

  As inorganic particles (external additives), particles of silica particles or metal oxides (more specifically, alumina, titania (titanium oxide), magnesium oxide, zinc oxide, strontium titanate, barium titanate, etc.) Are preferable, and one or more kinds of particles selected from the group consisting of silica particles and titania particles are particularly preferable.

  The resin particles (external additives) are preferably resin particles containing one or more resins selected from the group consisting of a crosslinked acrylic resin and a crosslinked styrene-acrylic resin, and the crosslinked styrene-acrylic resin. Particles are particularly preferred. The cross-linked acrylic acid resin and the cross-linked styrene-acrylic acid resin each have excellent chargeability and are easier to produce fine particles than melamine resins and the like.

The external additive particles may be surface-treated. For example, when silica particles are used as the external additive particles, hydrophobicity and / or positive chargeability may be imparted to the surface of the silica particles by the surface treatment agent. Examples of the surface treatment agent include a coupling agent (more specifically, a silane coupling agent, a titanate coupling agent, or an aluminate coupling agent), or silicone oil (more specifically, dimethyl silicone oil). Etc.) can be suitably used. As the silane coupling agent, a silane compound (more specifically, methyltrimethoxysilane, aminosilane or the like) may be used, or a silazane compound (more specifically, HMDS (hexamethyldisilazane) or the like). May be used. When the surface of the silica particles is treated with the surface treatment agent, a large number of hydroxyl groups (—OH) present on the surface of the silica particles are partially or entirely substituted with functional groups derived from the surface treatment agent. As a result, silica particles having a functional group derived from the surface treating agent (specifically, a functional group that is more hydrophobic and / or positively charged than the hydroxyl group) on the surface can be obtained. For example, when the surface of the silica particles is treated with a silane coupling agent having an amino group, the hydroxyl group of the silane coupling agent (for example, a hydroxyl group generated by hydrolysis of the alkoxy group of the silane coupling agent with moisture) A dehydration condensation reaction (“A (silica particle) —OH” + “B (coupling agent) —OH” → “AO—B” + H ₂ O) occurs with a hydroxyl group present on the surface of the silica particle. By such a reaction, the amino group is imparted to the surface of the silica particle by chemically bonding the silane coupling agent having an amino group and the silica particle. More specifically, the hydroxyl group present on the surface of the silica particles is substituted with a functional group having an amino group at the end (more specifically, —O—Si— (CH ₂ ) ₃ —NH ₂ or the like). Silica particles provided with amino groups tend to have a stronger positive charge than untreated silica particles. When a silane coupling agent having an alkyl group is used, a hydroxyl group present on the surface of the silica particle is converted into a functional group having an alkyl group at the end (more specifically, − it can be replaced by O-Si-CH _3, etc.). Thus, the silica particle to which the hydrophobic group (alkyl group) was provided instead of the hydrophilic group (hydroxyl group) tends to have stronger hydrophobicity than the untreated silica particle.

[Carrier particles]
The carrier particles may be carrier particles without a coat layer (for example, ferrite carrier particles), or may be carrier particles with a coat layer (hereinafter referred to as coated carrier particles). In order to form a high-quality image over a long period of time using a developer, it is preferable to use coated carrier particles. The coated carrier particles include a carrier core and a coat layer that covers the surface of the carrier core. The coat layer may cover the entire surface of the carrier core, or may partially cover the surface of the carrier core.

  Hereinafter, suitable examples of the coated carrier particles will be described. The coated carrier particle includes a carrier core and a coat layer. In addition, you may use the carrier core which has the following structure as carrier particles as it is, without covering with a coating layer.

(Career core)
The carrier core preferably contains a magnetic material. The carrier core may be magnetic material particles, or the magnetic material particles may be dispersed in the binder resin of the carrier core. Examples of the magnetic material contained in the carrier core include magnetite, barium ferrite, maghemite, Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg ferrite, Ca—Mg ferrite, Li ferrite, and Cu—Zn ferrite. Metal oxides are preferred, and magnetite is particularly preferred. As a material for each carrier core, one type of magnetic material may be used alone, or two or more types of magnetic materials may be used in combination. A commercially available product may be used as the carrier core. Also, the carrier core may be made by pulverizing and firing the magnetic material. In the production of the carrier core, the saturation magnetization of the carrier can be adjusted by changing the amount of magnetic material added (particularly, the proportion of the ferromagnetic material). Further, in the production of the carrier core, the circularity of the carrier can be adjusted by changing the firing temperature.

(Coat layer)
The coat layer is formed on the surface of the carrier core so as to cover the carrier core. The coat layer is substantially composed of a resin. Additives may be dispersed in the resin constituting the coat layer. Examples of the method for forming the coat layer include a method of immersing the carrier core in a liquid containing a resin (or resin material), or a liquid containing a resin (or resin material) in the carrier core in the fluidized bed. The method of spraying is mentioned.

  In order to improve the durability of the carrier, the amount of resin (coating resin) covering the carrier core is preferably 0.5% by mass or more and 5.0% by mass or less. The amount (unit: mass%) of the coating resin is represented by the formula “amount of coating resin = 100 × the mass of the coating resin / the total of the mass of the carrier core and the coating resin”. In order to improve the durability of the carrier, the coat layer preferably covers 90% or more of the surface area of the carrier core, and more preferably covers 100% of the area. .

  As the resin constituting the coat layer, a thermoplastic resin (more specifically, the “preferable thermoplastic resin” described above, or a fluororesin) may be used, or a thermosetting resin (more specifically, The above-mentioned “preferable thermosetting resin” or silicone resin may be used. Moreover, you may provide crosslinking | crosslinked property to a thermoplastic resin by mixing a thermoplastic monomer and a hardening | curing agent. The coat layer may have a sea-island structure.

  In order to reduce the adhesion (easy to adhere) of the carrier particles, the coat layer preferably contains a fluororesin. In addition, when the coat layer contains one or more resins selected from the group consisting of polyamideimide resin (PAI) and polyimide resin (PI), and a fluororesin, the content of the fluororesin relative to the entire coat layer The amount is preferably 50% by mass or more and 90% by mass or less. The content (unit: mass%) of the fluororesin is represented by the formula “content of fluororesin = 100 × mass of fluororesin in the coat layer / mass of the entire coat layer”. If the content of the fluororesin is too small, the charge imparting property of the carrier tends to be insufficient. Moreover, when there is too much content of a fluororesin, a fluororesin particle | grain will liberate too much from a coating layer, or it will become difficult to disperse | distribute a fluororesin in a coating layer. Examples of the fluororesin contained in the coating layer include polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene (PTFE), polytrifluoroethylene (more specifically, polychlorotrifluoroethylene, etc.), polyhexafluoropropylene. One or more resins selected from the group consisting of tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) are preferred, and FEP or PFA is particularly preferred preferable.

  Examples of the present invention will be described. Table 1 shows apparatuses D-1 to D-14 (image forming apparatuses) according to Examples or Comparative Examples, and toners TA-1 to TA-5 and TB-1 to TB-9 used in each apparatus. Indicates. Table 2 shows external additives (resin particles A-1 to A-4 and B-1 to B-4) used in the production of the toners shown in Table 1.

  Hereinafter, a manufacturing method, an evaluation method, and an evaluation result of the devices D-1 to D-14 will be described in order. In the evaluation in which an error occurs, a considerable number of measurement values with sufficiently small errors are obtained, and the arithmetic average of the obtained measurement values is used as the evaluation value. A scanning electron microscope (SEM) was used to measure the number average primary particle size of each of the resin particles and inorganic particles.

[Preparation of materials]
(Preparation of resin particles A-1 to A-4)
In a 4-liter flask having a capacity of 1 L equipped with a stirrer, a cooling tube, a thermometer, and a nitrogen introduction tube, 600 g of ion-exchanged water, 6 g of emulsifier (DBS: sodium dodecylbenzenesulfonate), and n-butyl methacrylate 100 g of (BMA), 20 g of styrene, 15 g of an initiator (BPO: benzoyl peroxide), and an amount of a crosslinking agent (DVB: divinylbenzene) shown in Table 2 were added. For example, in the preparation of the resin particle A-1, 70 g of a crosslinking agent (divinylbenzene) was added. Further, in the preparation of the resin particle A-2, 20 g of a crosslinking agent (divinylbenzene) was added. Moreover, in preparation of resin particle A-3, 18 g of a crosslinking agent (divinylbenzene) was added. Moreover, 85 g of a crosslinking agent (divinylbenzene) was added in the preparation of the resin particles A-4. The purity (mass fraction) of divinylbenzene (DVB) used as a crosslinking agent was 80%.

  Subsequently, while stirring the contents of the flask, nitrogen gas was introduced into the flask to create a nitrogen atmosphere inside the flask. Further, while stirring the flask contents, the temperature of the flask contents is increased to 90 ° C. in a nitrogen atmosphere, and the flask contents are reacted for 3 hours (specifically, a polymerization reaction) in a nitrogen atmosphere and a temperature of 90 ° C. It was. As a result, an emulsion containing a reaction product having a number average primary particle diameter of 90 nm was obtained. Subsequently, the obtained emulsion was cooled, and resin particles A-1 to A-4 having a number average primary particle size of 90 nm were obtained through a washing step and a dehydrating step.

(Preparation of resin particles B-1 to B-4)
The polymerization reaction described above so that the number average primary particle size of the reaction product is the value shown in Table 2 (B-1: 70 nm, B-2: 200 nm, B-3: 60 nm, B-4: 220 nm). Resin particles B-1 to B-4 were obtained in the same manner as the method for preparing the resin particles A-1, except that the time (3 hours for the resin particles A-1) was changed. In addition, there exists a tendency for the particle diameter of a reaction product (and resin particle) to become large, so that polymerization reaction time is lengthened.

With respect to the resin particles A-1 to A-4 and B-1 to B-4 obtained as described above, the blocking rate (specifically, pressurization for 5 minutes at a temperature of 160 ° C. and a pressure of 0.1 kgf / mm ² was performed. Thereafter, the measurement results of the blocking rate measured with a mesh having an opening of 75 μm were as shown in Table 2. For example, the blocking rate of the resin particle A-1 was 20%. The method for measuring the blocking rate was as follows.

<Measurement method of blocking rate>
As a measuring jig, a base (material: austenitic stainless steel) with a cylindrical hole (diameter: 10 mm, depth: 10 mm) and a cylindrical indenter (diameter: 10 mm, material: austenitic stainless steel) And an apparatus (manufactured by Kyocera Document Solutions Co., Ltd.) equipped with a heater.

Under an environment of a temperature of 23 ° C. and a humidity of 50% RH, resin particles (resin particles A-1 to A-4 and B-1 to B-4 as measurement objects) are placed in a hole (measurement site) of a jig. ) 10 mg was charged. The measurement site was heated to 160 ° C. with a jig heater, and a pressure of 0.1 kgf / mm ² was applied to the measurement site (resin particles) with a jig indenter (load: about 100 N) for 5 minutes. Thereafter, the entire amount of the resin particles at the measurement site (in the hole) was collected and set on a sieve (200 mesh defined by JIS Z8801-1) having a mesh size of 75 μm. And the mass of the sieve containing resin particles was measured, and the mass of resin particles on the sieve (the mass of resin particles before suction) was determined.

Subsequently, using a suction machine (“V-3SDR” manufactured by Amano Co., Ltd.), resin particles on the sieve were sucked from the lower side of the sieve. By this suction, only non-blocking resin particles out of the resin particles on the sieve passed through the sieve. After the suction, the mass of the resin particles that did not pass through the sieve (resin particles remaining on the sieve) was measured. Based on the mass of the resin particles before suction and the mass of the resin particles after suction (the mass of the resin particles that did not pass through the sieve), the blocking rate (unit: mass%) was determined according to the following formula. .
Blocking rate = 100 × mass of resin particles after suction / mass of resin particles before suction

[Production of toner]
(Preparation of toner base particles)
Using an FM mixer (Nihon Coke Kogyo Co., Ltd.), 100 parts by mass of a polyester resin (acid value: 5.6 mg KOH / g, softening point (Tm): 105 ° C.) and a colorant (CI Pigment Blue 15) : 3, component: copper phthalocyanine pigment) 4 parts by mass, quaternary ammonium salt ("BONTRON (registered trademark) P-51" manufactured by Orient Chemical Co., Ltd.) 1 part by mass, ester wax (manufactured by NOF Corporation " Nissan Electol (registered trademark) WEP-3 ”, melting temperature: 73 ° C.) and 5 parts by mass were mixed.

Subsequently, the obtained mixture was melt-kneaded using a twin-screw extruder (“PCM-30” manufactured by Ikegai Co., Ltd.). Subsequently, the obtained kneaded product was cooled and then pulverized using a pulverizer (“Turbo Mill” manufactured by Freund Turbo). Subsequently, the obtained pulverized product was classified using a classifier (“Elbow Jet EJ-LABO type” manufactured by Nippon Steel Mining Co., Ltd.). As a result, toner mother particles having a volume median diameter (D ₅₀ ) of 6.8 μm were obtained.

(First external addition)
Using a 10 L FM mixer (manufactured by Nihon Coke Kogyo Co., Ltd.) having a temperature control jacket, 100 parts by weight of toner base particles prepared in the above-described procedure while circulating water at a temperature of 20 ° C. through the jacket; The first external additive shown in Table 1 was mixed for a predetermined time (the time shown in Table 1 determined for each toner). The first external additive was any one of silica particles, titania particles, resin particles A-1, and colloidal silica particles shown in Table 1 defined for each toner. The amount of the first external additive added was 1 part by mass with respect to 100 parts by mass of the toner base particles in the manufacture other than the toner TA-5. In the production of toner TA-5, 0.8 part by mass of silica particles and 0.4 part by mass of titania particles were added to 100 parts by mass of toner base particles. The mixing at this timing corresponds to the “first external addition” in Table 1. The first external additive adhered to the surface of the toner base particles by the first external addition.

  For example, in the production of toner TA-1, 100 parts by mass of toner base particles and 1 part by mass of silica particles were mixed for 15 minutes using an FM mixer. In the production of the toner TA-5, 100 parts by mass of toner base particles, 0.8 parts by mass of silica particles, and 0.4 parts by mass of titania particles were mixed for 15 minutes using an FM mixer. In the production of toner TB-3, 100 parts by mass of toner base particles and 1 part by mass of resin particles (resin particles A-1 prepared by the above-described procedure) were mixed for 5 minutes using an FM mixer. In the production of the toner TB-8, 100 parts by mass of toner base particles and 1 part by mass of colloidal silica particles having a number average primary particle diameter of 100 nm were mixed for 15 minutes using an FM mixer. As the silica particles, positively-charged silica particles (“AEROSIL (registered trademark) RA200” manufactured by Nippon Aerosil Co., Ltd.), content: dry silica particles imparted with hydrophobicity and positive chargeability by surface treatment, surface treatment agent: hexamethyl Disilazane (HMDS) and aminosilane, number average primary particle size: about 12 nm) were used. As titania particles, hydrophilic titania particles (“STT-65C” manufactured by Titanium Industry Co., Ltd., titania crystal type: anatase, surface treatment agent: triethanolamine, number average primary particle size: about 40 nm) were used.

(Second external addition)
Subsequently, for the FM mixer, the second external additive shown in Table 1 (silica particles, resin particles A-1 to A-4 and B-1 to B shown in Table 1 defined for each toner). -4 and any one of colloidal silica particles) 1 part by mass was further added. For example, in the production of the toner TA-1, 1 part by mass of resin particles (resin particle A-1 prepared by the above-described procedure) is added to 100 parts by mass of toner base particles in the FM mixer. In the production of the toner TB-3, 1 part by mass of silica particles was added to 100 parts by mass of the toner base particles in the FM mixer. As the silica particles, positively charged silica particles (AEROSIL RA200) were used. In the production of the toner TB-8, 1 part by mass of colloidal silica particles (number average primary particle size: 100 nm) was added to 100 parts by mass of the toner base particles in the FM mixer.

  Subsequently, mixing by the FM mixer was performed for a predetermined time (the time shown in Table 1 determined for each toner). The mixing at this timing corresponds to the “second external addition” in Table 1. For example, in the production of the toner TA-1, using the FM mixer, the toner base particles having the first external additive (silica particles) attached to the surface and the second external additive (resin particles A-1) are used. For an additional 5 minutes. By the second external addition, the second external additive further adhered to the surface of the toner base particles to which the first external additive adhered.

  Thereafter, the obtained powder was sieved using a 200-mesh (aperture 75 μm) sieve. As a result, toners (toners TA-1 to TA-5 and TB-1 to TB-9) containing a large number of toner particles (non-capsule toner particles) were obtained.

  Regarding toners TA-1 to TA-5 and TB-1 to TB-9 obtained as described above, the liberation rate of external additives (inorganic particles and resin particles) (specifically, ultrasonic treatment is performed for 5 minutes) Table 1 shows the measurement results of the liberation rate measured for the toner dispersion in the same state. For example, in toner TA-1, the release rate of inorganic particles was 3%, and the release rate of resin particles was 20%. The method for measuring the liberation rate was as follows.

<Measurement method of liberation rate>
The release rate of each of the inorganic particles and the resin particles was measured for the toner dispersion in which the ultrasonic treatment was performed for 5 minutes. Specifically, after the toner dispersion is filtered to remove inorganic particles released in the toner dispersion, the toner remaining in the toner dispersion (hereinafter referred to as “sample after ultrasonic treatment”) is fluorescent X X-ray analysis and GC / MS analysis were performed to obtain a fluorescent X-ray spectrum and a GC / MS mass spectrum, respectively. Separately from the sample after sonication, a sample before sonication (hereinafter referred to as “initial sample”) is also subjected to X-ray fluorescence analysis and GC / MS analysis, respectively. A GC / MS mass spectrum was obtained. And the freezing rate of the inorganic particle was calculated | required by contrasting the fluorescence X-ray spectrum of the sample after ultrasonic treatment, and the fluorescence X-ray spectrum of an initial stage sample. Further, the GC / MS method mass spectrum of the sample after ultrasonic treatment was compared with the GC / MS method mass spectrum of the initial sample to obtain the release rate of the resin particles. Details of the ultrasonic treatment, fluorescent X-ray analysis, GC / MS analysis, and how to determine the liberation rate were as follows.

(Sonication)
Toner dispersion liquid was prepared by dispersing 2.0 g of a sample (toner) in 100 g of a 2% by weight aqueous solution of a nonionic surfactant (Emulgen (registered trademark) 120 manufactured by Kao Corporation, component: polyoxyethylene lauryl ether). Got. Subsequently, the obtained toner dispersion was subjected to ultrasonic treatment for 5 minutes using an ultrasonic disperser (“Ultrasonic Miniwelder P128” manufactured by Ultrasonic Industrial Co., Ltd., output: 100 W, oscillation frequency: 28 kHz). . Subsequently, using a separate type suction filtration device (filter bell and Buchner funnel) set with qualitative filter paper (“FILTER PAPER No. 1” manufactured by Advantech Co., Ltd., pore diameter of about 5 μm), ultrasonic treatment was performed as described above. The toner dispersion was suction filtered. Thereafter, reslurry to which 50 mL of ion exchange water was added and suction filtration were repeated three times to remove the surfactant attached to the surface of the toner particles.

  Thereafter, the filter paper used for washing was transferred together with the toner remaining on the filter paper to an aluminum dish (aluminum container), and the aluminum dish was placed in a vacuum constant temperature dryer and vacuum dried at 40 ° C. for 12 hours. As a result, a sample after sonication was obtained.

(X-ray fluorescence analysis)
The sample after sonication and the initial sample were measured. 1.5 g of toner as a measurement object was pressure-molded under the conditions of a pressure of 20 MPa and a pressurization time of 3 seconds to produce a cylindrical pellet having a diameter of 30 mm. Subsequently, the obtained pellet is subjected to fluorescent X-ray analysis to obtain a fluorescent X-ray spectrum (horizontal axis: energy, vertical axis: intensity (number of photons)) including a peak derived from the detection target (predetermined element). It was. The detection target was a characteristic element in the inorganic particles used as the external additive. For example, a sample (toner) using silica particles as an external additive was subjected to fluorescent X-ray analysis under the following conditions using Si (silicon) as a detection target.
・ Analyzer: Scanning X-ray fluorescence analyzer (“ZSX” manufactured by Rigaku Corporation)
・ X-ray tube (X-ray source): Rh (Rhodium)
Excitation conditions: tube voltage 50 kV, tube current 50 mA
・ Measurement area (X-ray irradiation range): Diameter 30mm
・ Measurement element: Si (silicon)

(How to find the release rate of inorganic particles)
Based on the fluorescent X-ray spectrum obtained for each of the sample after ultrasonication and the initial sample by the fluorescent X-ray analysis, the liberation rate of the inorganic particles (external additive) was calculated. Specifically, the derived inorganic particles peak intensity X _A sample after sonication, an inorganic particle-derived peak intensity X _B of the initial sample, according to the equation _{"X T = 100 × (X B} -X A) / X B " It was calculated liberation percentage X _T of the inorganic particles. In toner TA-5, silica particle-derived peak intensity X _A1 of the sample after ultrasonic treatment, silica particle-derived peak intensity X _{B1 of} the initial sample, titania particle-derived peak intensity X _{A2 of the} sample after ultrasonic treatment, The release of inorganic particles from the titania particle-derived peak intensity X _{B2 of the} initial sample according to the formula “X _T = 100 × {(X _B1 −X _A1 ) + (X _B2 −X _A2 )} / (X _B1 + X _B2 )” The rate _XT was calculated.

(GC / MS analysis)
The sample after sonication and the initial sample were measured. As a measuring device, a gas chromatograph mass spectrometer (“GCMS-QP2010 Ultra” manufactured by Shimadzu Corporation) and a multi-shot pyrolyzer (“PY-3030D” manufactured by Agilent Technologies) were used. As a column, a GC column ("Agilent (registered trademark) J & W Ultra Inert Capillary GC Column DB-5ms" manufactured by Agilent Technologies, Inc.), phase: an arylene phase in which allylene is reinforced with a siloxane polymer to strengthen the main chain of the polymer, inner diameter: 0.25 mm, film thickness: 0.25 μm, length: 30 m). With respect to 100 μg of the toner to be measured, GC / MS analysis was performed under the following conditions, and a mass spectrum including peaks derived from resin particles (external additives) (horizontal axis: ion mass / ion charge number, vertical axis: Detection intensity) was obtained.
・ Pyrolysis temperature: Furnace “600 ° C”, interface part “320 ° C”
Temperature rising condition: The temperature was raised from 40 ° C. to 320 ° C. at a rate of 28 ° C./min and held at 320 ° C. for 5 minutes.
Carrier gas: Helium (He) gas (linear velocity 36.1 cm / min)
Column head pressure: 49.7 kPa
Injection mode: split injection (split ratio 1: 200)
Carrier flow rate: total flow rate “204 mL / min”, column flow rate “1 mL / min”, purge flow rate “3 mL / min”

(How to determine the release rate of resin particles)
The liberation rate of the resin particles (external additive) was calculated based on the mass spectrum (GC / MS method mass spectrum) obtained for each of the sample after sonication and the initial sample by the GC / MS analysis. Specifically, a resin particle-derived peak area Y _A sample after sonication, a resin particle-derived peak area Y _B of the initial sample, according to the equation _{"Y T = 100 × (Y B} -Y A) / Y B " The release rate Y _T of the resin particles was calculated.

[Manufacture of carriers]
39.7 mol% in terms of MnO, 9.9 mol% in terms of MgO, 49.6 mol% calculated as Fe ₂ O _3, each raw material (MnO to be 0.8 mol% in terms of SrO, MgO, Fe ₂ O ₃ and SrO raw materials) were mixed in appropriate amounts, and water was added to the raw materials. Subsequently, the raw materials were ground using a wet ball mill for 10 hours and then mixed. Subsequently, the resulting mixture was dried. Subsequently, the dried mixture was subjected to heat treatment at a temperature of 950 ° C. for 4 hours.

Subsequently, using a wet ball mill, the mixture after the heat treatment was pulverized over 24 hours to prepare a slurry. Subsequently, the resulting slurry was dried and granulated with a spray dryer. Subsequently, the dried granulated product was crushed after being held in an atmosphere at a temperature of 1270 ° C. and an oxygen concentration of 2% for 6 hours. Thereafter, by adjusting the particle size, powder of Mn—Mg—Sr ferrite particles (magnetic carrier core) having a saturation magnetization of 70 Am ² / kg in an applied magnetic field of 3000 (10 ³ / 4π · A / m) ( Number average primary particle size: 35 μm) was obtained.

  Subsequently, a polyamideimide resin (copolymer of trimellitic anhydride and 4,4'-diaminodiphenylmethane) was diluted with water to prepare a resin solution having a solid content concentration of 10% by mass. Subsequently, PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) containing perfluorooctanoic acid at a mass ratio of 3 ppm and a nonionic surfactant (polyoxyethylene alkyl ether) are contained in the obtained resin solution. The carrier coating solution was obtained by dispersing. With respect to the obtained carrier coat liquid, the mass ratio of polyamideimide resin and PFA (polyamideimide resin: PFA) was 2: 8.

  Subsequently, the carrier coat liquid prepared as described above and the magnetic carrier core (Mn—Mg—Sr ferrite particle powder prepared by the above-described procedure) were mixed with a tumbling fluid coating apparatus (manufactured by POWREC Co., Ltd.). The magnetic carrier core was coated with the carrier coating solution using a tumbling fluidized coating apparatus. Subsequently, the magnetic carrier core coated with the resin was fired at 250 ° C. for 1 hour. Subsequently, the obtained fired product was cooled and then crushed. As a result, the surface of the magnetic carrier core was coated with a coating layer (resin layer) at a resin coating amount of 2% by mass, and the magnetic carrier core (magnetic material: Mn—Mg—Sr ferrite) and the coating layer (resin: polyamideimide resin) A carrier containing a large number of carrier particles provided with a mixed resin with PFA) was obtained. The resin coating amount (unit: mass%) is represented by the formula “resin coating amount = 100 × the mass of the coating resin / the total mass of the resin-coated ferrite carrier”.

[Manufacture of image forming apparatus]
(Preparation of two-component developer)
9 parts by mass of toner (any one of the toners TA-1 to TA-5 and TB-1 to TB-9 shown in Table 1 determined for each apparatus), and 100 parts by mass of the carrier manufactured by the above-described procedure; Was mixed for 30 minutes using a powder mixer (“Rocking Mixer (registered trademark)” manufactured by Aichi Electric Co., Ltd., mixing method: container rotation and rocking method) to prepare a two-component developer. For example, in the preparation of the two-component developer for the apparatus D-1, the toner TA-1 and the carrier are mixed. In preparation of the two-component developer for the apparatus D-6, the toner TB-1 and the carrier were mixed.

(Input developer)
The two-component developer prepared as described above is used as a color printer (“FS-C5250DN” manufactured by Kyocera Document Solutions Co., Ltd.), photosensitive drum: organic photosensitive drum having a single-layer type photosensitive layer, charging device: contact charging method. The charging roller). A color printer includes a developing device configured to develop an electrostatic latent image formed on a photosensitive member with toner, and a replenishing toner container configured to replenish replenishing toner to a housing portion of the developing device. It was equipped with. The two-component developer (two-component developer including the toner shown in Table 1) specified for each apparatus is put into the developing device of the color printer, and the replenishment toner (specified in Table 1 is shown in Table 1). Any one of the toners TA-1 to TA-5 and TB-1 to TB-9) was put into a toner container for supply of the color printer. For example, in the manufacture of the device D-1, a mixture (two-component developer) of the toner TA-1 and the carrier is put into a housing portion of the developing device of the color printer, and the toner TA-1 is placed in the replenishment toner container of the color printer. Was introduced. As a result, devices D-1 to D-14 (each image forming device) were obtained. In the initial state of each apparatus, a developer containing toner (any of toners TA-1 to TA-5 and TB-1 to TB-9) shown in Table 1 is stored in the storage unit of the developing device. It was.

[Evaluation method]
The evaluation methods of the devices D-1 to D-14 (hereinafter referred to as target devices) are as follows.

(Print life test)
300,000 consecutive sample images with a printing rate of 5% on the recording medium (printing paper) using the target device (any of devices D-1 to D-14) in an environment of temperature 23 ° C and humidity 50% RH A printing durability test (hereinafter referred to as 5% printing durability) was performed. Continuously, a printing durability test (hereinafter referred to as 30%), in which a sample image with a printing rate of 30% is continuously printed on a recording medium (printing paper) on a recording medium (printing paper) using the target apparatus in an environment of a temperature of 23 ° C. and a humidity of 50% RH (Described as printing durability). In image formation during the printing durability test, the surface of the photosensitive drum was charged while being in contact with the surface of the photosensitive drum. Subsequently, an electrostatic latent image was formed on the surface of the photosensitive drum by exposing the surface of the charged photosensitive drum. Subsequently, the toner in the accommodating portion of the developing device was supplied to the photosensitive drum, and the electrostatic latent image was developed with the toner.

(Image density, fog density)
A sample image including a solid portion is printed on a recording medium at the initial timing (before 5% printing start), after 5% printing and after 30% printing, and the image density (ID) of the recording medium is printed. The fog density (FD) was measured.

  In the measurement of the image density (ID), the reflection density (ID: solid part of the formed sample image) of the recording medium after printing is measured using a reflection densitometer (“RD914” manufactured by X-Rite). Image density) was measured.

In the measurement of the fog density (FD), the reflection density of the blank portion of the recording medium after printing (the blank portion of the formed sample image) was measured using a reflection densitometer (“RD914” manufactured by X-Rite). . Then, the fog density (FD) was calculated based on the following equation.
FD = (reflection density of blank area) − (reflection density of unprinted paper)

  When the image density (ID) was 1.300 or more, it was evaluated as ◯ (good), and when it was less than 1.300, it was evaluated as x (not good). If the fog density (FD) was less than 0.011, it was judged as ◯ (good), and if the fog density (FD) was 0.011 or more, it was judged as x (not good).

(Charging roller contamination)
A halftone image having a printing rate of 50% was formed on the entire surface of the A4 size printing paper by using the target device at each timing after 5% printing and 30% printing. Subsequently, it was visually confirmed whether or not there was a streak pattern in the formed halftone image. Further, after the halftone image was formed, it was visually confirmed whether or not the surface of the charging roller (charging device) of the target device was dirty (particularly, adhesion of toner components). If the streak pattern cannot be confirmed in the halftone image by visual observation, and the stain on the surface of the charging roller cannot be confirmed, it is evaluated as “good”. Not good). Note that the charging roller is more likely to be contaminated as the number of printed sheets in the printing durability test is larger and the printing rate in the printing durability test is larger.

(Photoconductor contamination, photoconductor wear)
After 30% printing durability, the surface of the photosensitive drum of the target apparatus was visually checked for contamination (particularly toner component adhesion), and the thickness of the photosensitive layer of the photosensitive drum was measured. When the surface of the photosensitive drum could not be confirmed by visual observation, it was evaluated as good (good), and when it was not “good”, it was evaluated as x (not good). The thickness of the photosensitive layer was measured using an eddy current film thickness meter (Helmut Fischer “FISCHERSCOPE (registered trademark) MMS (registered trademark) 3AM type”). When the thickness of the photosensitive layer after 30% printing durability exceeds 15 μm, it was evaluated as “good”, and when the thickness of the photosensitive layer after 30% printing durability was 15 μm or less, it was evaluated as “poor” (not good). . When the thickness of the photosensitive layer in the photosensitive drum is 15 μm or less, the fog density (FD) tends to increase due to a decrease in the surface potential of the photosensitive drum. In any of the devices D-1 to D-14, the initial thickness of the photosensitive layer was 40 μm.

[Evaluation results]
For each of the devices D-1 to D-14, the image density (after initial 5% printing and after 30% printing) and fog density (initial 5% after printing and 30% after printing) were evaluated. The results are shown in Table 3. For each of the devices D-1 to D-14, photoconductor abrasion (thickness of the photosensitive layer after 30% printing durability), photoconductor contamination (presence of contamination after 30% printing durability), and charging roller contamination Table 4 shows the results of the evaluation (presence or absence of contamination in each after 5% printing and 30% printing). “-” In Table 3 and Table 4 indicates that the other evaluations were bad and thus were not measured.

The devices D-1 to D-5 (image forming apparatuses according to Examples 1 to 5) each had the above-described basic configuration. Specifically, each of the devices D-1 to D-5 includes an image carrier (specifically, a photosensitive drum), a contact charging type charging device (specifically, a charging device including a charging roller as a charging member), and An exposure device and a developing device were provided. In the initial state, the developer containing the toner (initial toner) (specifically, the two-component developer) is substantially contained in the accommodating portion of the developing device. The toner particles were provided with inorganic particles and resin particles as external additives (see Table 1). The number average primary particle size of the resin particles was 70 nm or more and 200 nm or less (see Tables 1 and 2). The blocking rate of the resin particles after pressing for 5 minutes at a temperature of 160 ° C. and a pressure of 0.1 kgf / mm ² was 20% by mass or more and 45% by mass or less as measured with a mesh having an opening of 75 μm (Table 1 and (See Table 2). The liberation rate of inorganic particles in the toner dispersion measured for the toner dispersion after ultrasonic treatment for 5 minutes is 5% or less in terms of the peak intensity ratio of the fluorescent X-ray spectrum. The liberation rate of the resin particles was 10% or more and 30% or less in the peak area ratio of the GC / MS method mass spectrum (see Tables 1 and 2).

  As shown in Tables 3 and 4, each of the devices D-1 to D-5 is continuously high while suppressing the wear of the photoreceptor, the contamination of the photoreceptor, and the contamination of the charging device in continuous printing. I was able to continue to form high quality images.

  The image forming apparatus and the image forming method according to the present invention can be used to form an image in, for example, a copying machine, a printer, or a multifunction peripheral.

DESCRIPTION OF SYMBOLS 10 Transfer device 11, 11a-11d Developing device 12, 12a-12d Photoconductor drum 13 Transfer belt 14a Drive roller 14b Driven roller 14c Tension roller 15a-15d Primary transfer roller 16 Secondary transfer roller 17 Fixing device 18 Cleaning device 20 Control Portion 21 Charging member 22 Exposure device 23 Cleaning blade 30 Toner base particle 31 Inorganic particle 32 Resin particle 100 Image forming device 111 Developing roller 112 Magnetic roller 112a Floating pole 112b Main pole 112c Regulating pole 112d Regulating blade 113 First stirring shaft 114 First 2 Stirrer shaft 115 Replenishment toner container 115a Replenishment amount adjusting member P Recording medium R1 Conveying section R2, R3 Storage

Claims (7)

An image carrier;
A charging device of a contact charging method for charging the surface of the image carrier while contacting the surface of the image carrier;
An exposure device that forms an electrostatic latent image on the surface of the image carrier by exposing the surface of the charged image carrier;
A developing device having an accommodating portion for accommodating a developer for developing the electrostatic latent image;
With
In the initial state, the storage portion substantially stores at least a developer containing toner,
The toner includes a plurality of toner particles including toner mother particles and an external additive attached to the surface of the toner mother particles;
The toner particles include inorganic particles and resin particles as the external additive,
The number average primary particle diameter of the resin particles is 70 nm or more and 200 nm or less,
The blocking rate of the resin particles after pressing for 5 minutes at a temperature of 160 ° C. and a pressure of 0.1 kgf / mm ² is 20% by mass or more and 45% by mass or less as measured with a mesh having an opening of 75 μm.
The liberation rate of the inorganic particles in the toner dispersion measured in the state of ultrasonic treatment for 5 minutes is 5% or less in terms of the peak intensity ratio of the fluorescent X-ray spectrum, The image forming apparatus, wherein a liberation rate of the resin particles in the toner dispersion is 10% or more and 30% or less as a peak area ratio of a GC / MS mass spectrum. The image carrier is an organic photosensitive drum,
The image forming apparatus according to claim 1, further comprising a cleaning blade for removing a substance attached to a surface of the organic photosensitive drum.   3. The image forming apparatus according to claim 1, wherein the inorganic particles and the resin particles have a laminated structure of the inorganic particles and the resin particles in this order from the surface of the toner base particles.   The image forming apparatus according to claim 1, wherein the resin particles contain one or more resins selected from the group consisting of a crosslinked acrylic resin and a crosslinked styrene-acrylic resin. .   The image forming apparatus according to claim 1, wherein the toner particles include one or more kinds of particles selected from the group consisting of silica particles and titania particles as the inorganic particles. In an initial state, the storage unit substantially stores a two-component developer containing the toner and carrier,
The carrier includes a plurality of carrier particles comprising a carrier core and a coat layer covering the surface of the carrier core,
The image forming apparatus according to claim 1, wherein the coat layer contains a fluororesin. Charging the surface of the image carrier while contacting the surface of the image carrier;
Forming an electrostatic latent image on the surface of the image carrier by exposing the surface of the charged image carrier;
Supplying toner in a container of a developing device to the image carrier and developing the electrostatic latent image with the toner;
Including
The toner includes a plurality of toner particles including toner mother particles and an external additive attached to the surface of the toner mother particles;
The toner particles include inorganic particles and resin particles as the external additive,
The number average primary particle diameter of the resin particles is 70 nm or more and 200 nm or less,
The blocking rate of the resin particles after pressing for 5 minutes at a temperature of 160 ° C. and a pressure of 0.1 kgf / mm ² is 20% or more and 45% or less as measured with a mesh having an opening of 75 μm.
The liberation rate of the inorganic particles in the toner dispersion measured in the state of ultrasonic treatment for 5 minutes is 5% or less as a peak intensity ratio by fluorescent X-ray analysis, The image forming method, wherein a liberation rate of the resin particles in the toner dispersion is 10% or more and 30% or less as a peak area ratio according to a GC / MS method.

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