JP2009122190A - Developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a developing device which prevents developer from continuing to be conveyed on a developer bearing member, even after development and can make compatible both the prolonged service life of the developer and development (image formation) with high image quality which is free of image density unevenness. <P>SOLUTION: In the developing device 2, in order to form a residual developer removing region r, in which developer 208 having reduced toner concentration, after development is, dropped from a developing sleeve 202 into a developer storage tank 207b, on an outer surface of the developing sleeve; a residual developer removing pole p is put on a surface part of a magnetic field generating means 201; an electrode plate 212 is disposed at a position opposite to the residual developer removing pole p (in the vicinity of the developing sleeve surface); and a bias is applied to the electrode plate, to form an electric field of a direction in which carrier is peeled from a developer bearing member 204 (in which the carriers move from the developer bearing member 204 to the electrode plate 212). According to this configuration, the developer which ends up continuing to be conveyed on the developer bearing member, even after development, can be peeled from the developer bearing member by the force of the electric field, and the developer continuing to be conveyed on the developer bearing member even after development can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device using a dry two-component developer, a process cartridge provided with the developing device, and a copying machine, a facsimile, a printer, or a composite machine including the developing device or the process cartridge. The present invention relates to a forming apparatus.

In an image forming apparatus such as a copying machine, a facsimile machine, a printer, or a complex machine of these, various developing devices (see, for example, Patent Documents 1 to 3) are used. Here, as an example of a conventional developing device, a configuration example of a developing device using a dry two-component developer composed of toner and a magnetic carrier is shown in FIGS.
As shown in FIGS. 8 and 9, the developing device 100 includes a developing roller 104 as a developer carrying member, and the developing roller 104 develops the developer 101 so as to face the image carrying member (for example, a photosensitive drum) 102. The toner is conveyed to the area 103 and the electrostatic latent image formed on the photosensitive drum 102 is developed with the toner of the developer 101 to form a toner image.

  The developing roller 104 has a cylindrical developing sleeve 105, and is accommodated in the developing sleeve 105 and forms a magnetic field so that the surface of the developing sleeve 105 causes the developer 101 to rise. A magnet roller 106 is provided. On the developing roller 104, when the developer 101 spikes, the magnetic carrier of the developer 101 spikes on the developing sleeve 105 so as to follow the lines of magnetic force generated by the magnet roller 106. The toner of the developer 101 adheres.

  Further, as shown in FIG. 10, this type of developing device 100 includes a storage tank 107 that stores the developer 101 and a screw-shaped stirring member (stir screw) that stirs the developer 101 in the storage tank 107. ) 108 and a developer regulating member (regulating blade) 109 that equalizes the amount of the developer 101 pumped up by the developing roller 104. Further, the developing device 100 shown in FIG. 8 (or FIG. 9) and FIG. 10 includes a storage tank 107 and a stirring screw 108, respectively.

  The developer 101 in the developing device 100 moves in the storage tank 107 as indicated by an arrow K in FIG. The toner replenished from one end of the one storage tank 107a on the side away from the developing roller 104 is conveyed by the stirring screw 108 to the other end of the one storage tank 107a along the axial direction of the stirring screw 108. The developer 101 is mixed and stirred. Then, the developer 101 moves from the other end of the one storage tank 107a into the other storage tank 107b near the developing roller 104.

  The developer 101 that has moved to the other storage tank 107 b near the developing roller 104 is pumped up to the surface of the developing sleeve 105 (attached to the surface of the developing sleeve 105) by the magnetic force of the magnet roller 106 of the developing roller 104. Thereafter, the amount of the developer 101 is made uniform by the regulating blade 109 and then conveyed to the developing region 103 where the photosensitive drum 102 and the developing roller 104 are opposed to each other with a space therebetween. Developer 101 develops the electrostatic latent image formed on photoconductor drum 102 to form a toner image.

  Here, the developing device 100 shown in FIG. 8 is provided with a regulating blade 109 on the upper side or the lateral side of the developing roller 104, and removes the developer 101 remaining after development at the lower side of the developing roller 104. Further, the developing device 100 shown in FIG. 9 is provided with a regulating blade 109 on the lower side of the developing roller 104, and removes the developer 101 remaining after the development on the upper side of the developing roller 104. As the developing device 100, the one shown in FIGS. 8 and 9 described above is properly used depending on the layout of other units such as the photosensitive drum 102.

In the developing device configured as described above, the agent running out is very important. If the agent running out is poor, the developed developer is transported on the developer carrying member without being contained in the developer containing layer. Since the toner is not replenished on the developer carrying member (hereinafter referred to as “accompaniment”), there is a problem that unevenness such as haze occurs in the image. In addition, the developer once separated from the developer carrying member due to the shortage of the agent is not mixed in the developer containing layer, and the same unevenness occurs even if the developer is pumped up immediately.
Therefore, in order to solve such a problem, in the prior art described in Patent Document 4, a developer stripping blade is installed in the agent running out region of the developer carrying member to forcibly run out the agent. In this case, the developer stripping blade may or may not be in sliding contact with the developer carrying member. However, in the case of sliding contact, the developer carrying member surface may be damaged, or the developer. There is a problem such as toner sticking to the carrier, and if it does not slide, the effect of removing the developer is reduced.

JP 2000-194194 A JP 2000-194195 A Japanese Patent Laid-Open No. 2000-250311 JP 2006-171067 A

By the way, the request | requirement of lifetime improvement of a developer is also increasing rapidly, and the lifetime of a developer is extended by increasing the film thickness of the coat layer of a carrier and making carrier resistance high resistance. However, the use of high resistance carriers creates new problems. For example, when a high-resistance carrier is used, after the solid image development, the developer does not run out at the run-out portion, and the used developer is brought along, and after one round of the developer carrier, the leading edge of the next image The phenomenon that the image density becomes thin occurred.
Here, the mechanism of the high resistance carrier is as follows. Since the carrier after the development is deprived of the toner, a counter charge corresponding to the charge of the toner accumulates, and the Q / M increases. When Q / M increases, the mirror image force increases, and the used developer is brought along without running out of the agent. For this reason, the above problems occur.

  The present invention has been made based on the above circumstances, and even when a high-resistance carrier is used, the developer is prevented from being carried around, the life of the developer is increased, and the image quality is not uneven. An object of the present invention is to provide a developing device capable of achieving both development (image formation), and further to provide a process cartridge including the developing device, and including the developing device or the process cartridge. An object of the present invention is to provide an image forming apparatus capable of forming a high-quality image without density unevenness.

In order to achieve the above object, the present invention employs the following solutions.
The first means of the present invention is “a cylindrical or columnar magnetic field generating means having a plurality of fixed magnetic poles on the surface portion, and is arranged coaxially with the axis of the magnetic field generating means so as to enclose the magnetic field generating means. Developer that develops an electrostatic latent image on an image carrier by carrying and transporting a developer composed of toner and carrier, comprising a hollow body (referred to as a developing sleeve) made of a rotated non-magnetic material A `` carrying member '', and `` a developer regulating member that is provided so as to face the developer carrying member and that is carried by the developer carrying member and regulates the amount of the developer conveyed to the image carrier ''; “A stirrer (provided upstream of the developer regulating member in the rotation direction of the developer carrying member and transporting the developer contained in the developer containing tank in the axial direction of the hollow body (developing sleeve) ( For example, a stirring member formed into a screw shape) In the developing device that has at least, an agent run-out area for dropping the developed developer having a low toner concentration from the hollow body (developing sleeve) into the developer containing tank is formed on the outer surface of the hollow body (developing sleeve). In addition to providing an agent breakage electrode on the surface portion of the magnetic field generating means, an electrode plate is disposed at a position facing the agent breakage electrode (for example, a position facing the agent breakage electrode in the vicinity of the surface of the developing sleeve). Further, a bias is applied to the electrode plate to form an electric field in a direction in which the carrier is peeled off from the developer carrying member.

According to a second means of the present invention, in the developing device of the first means, the carrier used for the developer has a volume resistivity of 1 × 10 ^14.5 Ω · cm or more and 1 × 10 ¹⁷ Ω · cm or less. It is characterized by being.
The third means of the present invention is characterized in that, in the developing device of the first or second means, at least a surface of the electrode plate facing the developer carrier is insulated.
The fourth means of the present invention is characterized in that, in the developing device of any one of the first to third means, a bias is applied to the electrode plate only during image formation.

According to a fifth means of the present invention, in the developing device of any one of the first to fourth means, the toner used for the developer has a volume average particle diameter of 3 to 8 μm, and a volume average particle diameter ( The ratio (Dv / Dn) of Dv) to the number average particle diameter (Dn) is in the range of 1.00 to 1.40.
According to a sixth means of the present invention, in the developing device of any one of the first to fifth means, the toner used for the developer has a shape factor SF-1 in the range of 100 to 180, The shape factor SF-2 is in the range of 100 to 180.
Further, according to a seventh means of the present invention, in the developing device of any one of the first to sixth means, the toner used for the developer is a polyester prepolymer having a functional group containing at least a nitrogen atom, polyester The toner is obtained by crosslinking and / or stretching reaction of a toner material liquid in which a colorant and a release agent are dispersed in an organic solvent in an aqueous medium.

According to an eighth means of the present invention, in the developing device of any one of the first to seventh means, the toner used for the developer is substantially spherical.
According to a ninth means of the present invention, in the developing device of any one of the first to seventh means, the toner used for the developer has a major axis r1, a minor axis r2, and a thickness. When r1 ≧ r2 ≧ r3, the ratio of the major axis r1 to the minor axis r2 (r2 / r1) is in the range of 0.5 to 1.0, and the thickness r3 and the minor axis r2 The ratio (r3 / r2) is in the range of 0.7 to 1.0.

  According to a tenth aspect of the present invention, in the process cartridge provided in the image forming unit of the image forming apparatus, the process cartridge includes at least an image carrier and a developing device of any one of the first to ninth means. The image forming apparatus main body is detachably provided.

The eleventh means of the present invention comprises an image carrier, a charging means for charging the image carrier, a means for forming an electrostatic latent image on the image carrier, and developing a latent image on the image carrier. An image forming apparatus including at least a developing unit that visualizes the image, wherein the developing unit includes a developing device of any one of first to ninth units.
The twelfth means of the present invention includes an image carrier, a means for forming an electrostatic latent image on the image carrier, and a developing means for developing and developing the latent image on the image carrier. An image forming apparatus including at least a process cartridge of the tenth means is provided.

In the developing device according to the present invention, an out-of-agent region is formed on the outer surface of the hollow body (developing sleeve) to drop the developed developer having a low toner concentration from the hollow body (developing sleeve) into the developer containing tank. In addition, an electrode plate is disposed on the surface portion of the magnetic field generating means, and an electrode plate is disposed at a position facing the agent break electrode (for example, a position facing the agent break electrode near the surface of the developing sleeve). The bias is applied to the surface to form an electric field in the direction of peeling the carrier from the developer carrier (electric field in the direction in which the carrier moves from the developer carrier to the electrode plate). The developer can be peeled off from the developer carrying member by the force of an electric field, and can be prevented from being electrostatically accompanied. Therefore, according to the present invention, it is possible to prevent electrostatic accompaniment due to the increase in carrier resistance accompanying the increase in the life of the developer, and to improve the life of the developer and develop high-quality images without image density unevenness. A developing device capable of achieving both (image formation) can be realized.
In addition, since the process cartridge and the image forming apparatus of the present invention include the above-described developing device, high-quality image formation without image density unevenness can be performed.

Hereinafter, the configuration, operation, and action of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. This image forming apparatus is an example of a so-called tandem type color image forming apparatus having four image forming units, which is yellow (hereinafter referred to as “Y”), cyan (hereinafter referred to as “C”), and magenta. A single-color, multi-color or full-color image is formed using four color toners (hereinafter referred to as “M”) and black (hereinafter referred to as “K”).

  First, a basic configuration of the image forming apparatus will be described. This image forming apparatus includes four photoconductors 1Y, 1C, 1M, and 1K as image carriers that form image forming units of respective colors in an image forming unit 30. Here, a drum-shaped photoconductor (photosensitive drum) is taken as an example, but a belt-shaped photoconductor can also be adopted. The photoconductors 1Y, 1C, 1M, and 1K are arranged in parallel along an intermediate transfer belt 10 as an intermediate transfer body, and are driven to rotate in the direction of the arrow in the drawing while being in contact with the intermediate transfer belt 10. . Each of the photoreceptors 1Y, 1C, 1M, and 1K is obtained by forming a photoconductive photosensitive layer on a relatively thin cylindrical conductive substrate and further forming a protective layer on the photosensitive layer. Further, an intermediate layer may be provided between the photosensitive layer and the protective layer.

The configuration around the four photoconductors 1Y, 1C, 1M, and 1K constituting the image forming unit for each color is the same, and the codes Y, C, M, and K for color classification are added after the numerals of the respective codes. .
More specifically, there are cleaning devices 7Y, 7C, 7M and 7K for removing the transfer residual toner from the photoconductors, and charging devices 3Y and 3C as charging means, around the photoconductors 1Y, 1C, 1M and 1K. 3M, 3K, and developing devices 2Y, 2C, 2M, and 2K as developing means. Here, the photoreceptors 1Y, 1C, 1M, and 1K of the image forming units, the developing devices 2Y, 2C, 2M, and 2K, the charging devices 3Y, 3C, 3M, and 3K, and the cleaning devices 7Y, 7C, 7M, and 7K, It is housed integrally in the cartridge and constitutes a process cartridge. The process cartridge is configured to be detachable from the main body of the image forming apparatus, and can be easily replaced. That is, the image forming apparatus shown in FIG. 1 has a configuration in which four process cartridges are detachably arranged along the intermediate transfer belt 10.

  Laser light emitted from the exposure device 4 as a latent image forming unit is provided between the charging devices 3Y, 3C, 3M, and 3K and the developing devices 2Y, 2C, 2M, and 2K of each image forming unit (process cartridge). Space is secured so that can pass up to the photoreceptor 1.

  In the charging devices 3Y, 3C, 3M, and 3K, for example, a rotatable roller-shaped charging member is disposed close to the photoreceptors 1Y, 1C, 1M, and 1K, and a voltage obtained by superimposing a direct current on an alternating current is charged on the charging member. The photoconductors 1Y, 1C, 1M, and 1K are charged by applying and discharging between the photoconductor and the charging member. The photosensitive member may be charged using a contact charging roller in contact with a charging member, or a non-contact charging charger or the like may be used. .

  On the surfaces of the photoreceptors 1Y, 1C, 1M, and 1K charged in this way, laser light is exposed by the exposure device 4, and electrostatic latent images corresponding to the respective colors are formed. The exposure device 4 writes an electrostatic latent image corresponding to each color on each photoconductor 1Y, 1C, 1M, 1K based on image information corresponding to each color. The exposure apparatus 4 of this embodiment includes a plurality of semiconductor laser light sources, a coupling optical system (collimating lens, aperture, cylindrical lens, etc.), an optical deflector (polygon mirror, pyramid mirror, vibration mirror, etc.), This is a laser scanning type exposure device consisting of a scanning imaging optical system (scanning imaging lens, lens for correcting curvature of field and aberration, folding mirror, etc.), etc., but exposure consisting of an LED array and imaging means Other types of exposure apparatuses such as an apparatus can also be employed.

  Each of the developing devices 2Y, 2C, 2M, and 2K is a biaxial transport type developing device 2 as shown in FIG. 2, and has a developer carrying body 204 that carries the developer and a screw that stirs and conveys the developer. The formed stirring member 206 (two stirring screws 206a and 206b) is provided. The two stirring screws 206a, 206b are separated from each other by the partition plate. Further, the developer carrier 204 is partially exposed from the opening of the casing. Here, a two-component developer composed of a toner and a magnetic carrier is used. A detailed description of the developing device will be described later.

  Each of the developing devices 2Y, 2C, 2M, and 2K receives toner of a corresponding color from the toner bottles 31Y, 31C, 31M, and 31K shown in FIG. Yes. The toner bottles 31Y, 31C, 31M, and 31K are configured to be detachable from the main body of the image forming apparatus so that they can be replaced individually. With such a configuration, only the toner bottles 31Y, 31C, 31M, and 31K may be replaced at the time of toner end. Therefore, other components that have not yet reached the end of their life when the toner ends can be used as they are, and the user's expense can be reduced.

  The toner of each color supplied from the toner bottles 31Y, 31C, 31M, and 31K into the developing devices 2Y, 2C, 2M, and 2K is agitated with the developer by the first agitating screw 206a and is supplied to the second agitating screw 206b on the supply side. And is carried on the developer carrying member 204 there. The developer carrier 204 is composed of a magnet roller 201 (or a plurality of fixed magnets) magnetized with a plurality of magnetic poles as magnetic field generating means fixed inside, and a nonmagnetic material that rotates coaxially therearound. And a hollow body (developing sleeve) 202. The developer in the agitating screw portion on the supply side is pumped up onto the developer carrier 204 by the magnetic force generated by the magnet roller 201, and after being thinned by the developer regulating member 205, the developer sleeve of the developer carrier 204. In the state where it stands up on 202, it is conveyed to the developing area facing the photoreceptor 1 (1Y, 1C, 1M, 1K).

  Here, the developer carrying member 204 moves in the same direction at a higher linear velocity than the surface of the photosensitive member 1 in a region facing the photosensitive member 1 (hereinafter referred to as “developing region”). Then, the carrier spiked on the developer carrying member 204 supplies the toner adhering to the carrier surface to the surface of the photosensitive member 1 while rubbing the surface of the photosensitive member 1. At this time, a predetermined developing bias is applied to the developer carrying member 204 from a power source (not shown), whereby a developing electric field is formed in the developing region. Then, between the electrostatic latent image on the photoreceptor 1 and the developer carrying member 204, an electrostatic force directed toward the electrostatic latent image side acts on the toner on the developer carrying member 204. As a result, the toner on the developer carrying member 204 is electrostatically attached to the electrostatic latent image on the photosensitive member 1. By this adhesion, the electrostatic latent image on the photoreceptor 1 is developed (developed) into a toner image of a corresponding color.

  The intermediate transfer belt 10 in the transfer device 6 is stretched around three support rollers 11, 12, and 13 and is configured to endlessly move in the direction of the arrow in the drawing. On the intermediate transfer belt 10, toner images on the photoreceptors 1Y, 1C, 1M, and 1K are transferred so as to overlap each other by an electrostatic transfer method. Although there is a configuration using a transfer charger in the electrostatic transfer system, a configuration using a transfer roller that generates little transfer dust is adopted here. Specifically, primary transfer rollers 14Y, 14C, 14M, and 14K as transfer devices 6 are disposed on the back surface of the portion of the intermediate transfer belt 10 that contacts the photoreceptors 1Y, 1C, 1M, and 1K, respectively. Here, a primary transfer nip portion is formed by the portions of the intermediate transfer belt 10 pressed by the primary transfer rollers 14Y, 14C, 14M, and 14K and the photoreceptors 1Y, 1C, 1M, and 1K. When transferring the toner images on the photoreceptors 1Y, 1C, 1M, and 1K onto the intermediate transfer belt 10, a positive bias is applied to each primary transfer roller. As a result, a transfer electric field is formed in each primary transfer nip portion, and the toner images on the photoreceptors 1Y, 1C, 1M, and 1K are electrostatically attached to the intermediate transfer belt 10 and transferred.

  The untransferred toner remaining on the photosensitive member without being transferred by the transfer device 6 is collected by the cleaning devices 7Y, 7C, 7M, and 7K7 and sent to a waste toner collecting bottle (not shown). Here, in the cleaning devices 7Y, 7C, 7M, and 7K, cleaning members such as fur brushes, rollers, and blades are in contact with the photoreceptors 1Y, 1C, 1M, and 1K, and the photoreceptors 1Y, 1C, 1M, and 1K The transfer residual toner is removed from the toner.

  A belt cleaning device 15 for removing toner remaining on the surface of the intermediate transfer belt 10 is provided around the intermediate transfer belt 10. The belt cleaning device 15 is configured to collect unnecessary toner adhering to the surface of the intermediate transfer belt 10 with a fur brush and a cleaning blade. The collected unnecessary toner is transported from the belt cleaning device 15 to a waste toner tank (not shown) by a transport means (not shown).

  Further, a secondary transfer roller 16 is disposed in contact with the portion of the intermediate transfer belt 10 stretched around the support roller 13. A secondary transfer nip portion is formed between the intermediate transfer belt 10 and the secondary transfer roller 16, and recording paper as a recording material is fed into this portion at a predetermined timing. The recording paper is accommodated in a paper feed cassette 20 on the lower side of the exposure apparatus 4 in the drawing, and is conveyed to the secondary transfer nip portion by a paper feed roller 21, a registration roller pair 22, and the like. Then, the toner images superimposed on the intermediate transfer belt 10 are collectively transferred onto the recording paper at the secondary transfer nip portion. At the time of this secondary transfer, a positive bias is applied to the secondary transfer roller 16, and the toner image on the intermediate transfer belt 10 is transferred onto the recording paper by the transfer electric field formed thereby.

  A heat fixing device 23 as a fixing unit is disposed downstream of the secondary transfer nip portion in the transfer paper conveyance direction. The heat fixing device 23 includes a heating roller 23a with a built-in heater and a pressure roller 23b for applying pressure. The recording paper that has passed through the secondary transfer nip is sandwiched between these rollers and receives heat and pressure. As a result, the toner on the recording paper is melted and the toner image is fixed on the recording paper. Then, the recording sheet after fixing is discharged onto a discharge tray on the upper surface of the apparatus by a discharge roller 24.

  Although one embodiment of the image forming apparatus according to the present invention has been described above, the present invention is not limited to this configuration. For example, FIG. 1 shows a tandem color image forming apparatus having four image forming units (process cartridges), but a monochrome image forming apparatus having only one image forming unit may be used. In FIG. 1, only the configuration of the color printer unit is shown. If a document image reading unit (scanner unit) is installed on the upper part of the printer unit, the configuration of a digital copying machine is obtained. Can be used as a facsimile or a digital multifunction machine.

  Next, a specific configuration of the developing device provided in the image forming unit (or process cartridge) of the image forming apparatus having the above configuration and a developer (carrier, toner) used in the developing device will be described.

[Description of developing device]
FIG. 2 is a schematic cross-sectional view of a developing device showing an embodiment of the present invention. In FIG. 2, the developing device 2 conveys the developer 208 to a developing area facing the image carrier (photosensitive drum) 1 and develops the electrostatic latent image formed on the surface of the image carrier 1. Thus, a developer carrying member (developing roller) 204 for forming a toner image is provided. The developer carrier 204 is formed in a cylindrical shape composed of a magnet roller 201 magnetized with a plurality of magnetic poles as a magnetic field generating means fixed inside, and a nonmagnetic material that rotates coaxially therearound. The developing sleeve 202 is constituted. The magnet roller 201 included in the developing sleeve 202 forms a magnetic field so as to cause the developer 208 to rise on the surface of the developing sleeve 202 in the developing region. In the developer carrying member 204, when the developer 208 rises, the magnetic carrier constituting the developer 208 rises on the developing sleeve 202 so as to follow the lines of magnetic force generated by the magnet roller 201. The toner constituting the developer 208 adheres to the raised magnetic carrier.

  In such a developing device 2, the developer storage tank 207 that stores the developer 208 described above in the casing, and a screw-shaped stirring member 206 (two pieces) that stirs the developer 208 in the developer storage tank 207. Stirring screws 206a and 206b) and a developer regulating member (for example, a regulating blade) 205 for making the amount of the developer 208 pumped up by the developer carrier 204 uniform. In the developing device 2 shown in FIG. 2, a pair of developer storage tank 207 and stirring member 206 (first developer storage tank 207a, second developer storage tank 207b, first stirring screw 206a, second stirring) Screw 206b).

  The developer 208 in the developing device 2 moves in the developer accommodating tank 207 in the axial direction of the stirring member 206. At one end of the first developer storage tank 207a on the side away from the developer carrying member 204, a toner replenishing unit for introducing the toner replenished from the toner bottle is provided. The toner replenished to one end of the first developer storage tank 207a is conveyed by the first stirring screw 206a to the other end of the first developer storage tank 207a along the axial direction of the first stirring screw 206a. It is mixed and stirred with the developer 208. Then, the developer 208 moves from the other end of the first developer storage tank 207a into the second developer storage tank 207b (on the supply side) near the developer carrier 204. The developer 208 transferred to the second developer storage tank 207b near the developer carrier 204 is conveyed by the second stirring screw 206b toward the opposite end along the axial direction of the second stirring screw 206b. However, a part of the developer is pumped onto the surface of the developing sleeve 202 by the magnetic force of the magnet roller 201 during the conveyance process (that is, adheres to the surface of the developing sleeve 202). Thereafter, the amount of the developer 208 is made uniform by the developer regulating member 205, and then, the image carrier 1 and the developer carrier 204 are conveyed to a developing area facing each other with a gap therebetween. Then, the developer 208 conveyed to the developing area is raised on the surface of the developing sleeve 202 to form a magnetic brush, and the electrostatic latent image formed on the image carrier 1 is developed with toner to be a visible image. (Toner image) is formed.

  The magnet roller 201 includes a plurality of fixed magnetic poles, for example, n1 (developer transport pole), n2 (developer feed pole), s1 (developer transport pole), n3 (developer pole) and s2 (developer transport pole). Are provided. Since the developing sleeve 202 of the developer carrying member 204 rotates in the direction of arrow g in the figure, the developer 208 moves on the surface of the developing sleeve 202 in the order of fixed magnetic poles n1, n2, s1, n3, and s2. In this magnet roller 201, the fixed magnetic pole n1 (developer conveying pole) and the fixed magnetic pole n2 (developer pumping pole) have the same N polarity, and the N polarity is between the fixed magnetic pole n1 and the fixed magnetic pole n2. When the magnetic pole p is provided, the developed developer 208 having a reduced toner concentration is contained in the second developer containing tank 207b by the repulsive force of the magnetic pole p in addition to the repulsive force of the fixed magnetic pole n1 and the fixed magnetic pole n2. Is dropped.

  In the present invention, such a magnetic pole p (P) is referred to as “agent breakage pole”, and the developed developer 208 is dropped into the second developer accommodating tank 207b by the repulsive force of the magnetic pole p (P). The region r to be removed is referred to as a “drug out region”. The developed developer 208 having a low toner concentration dropped into the second developer storage tank 207b (that is, the agent has been cut off) in this way is first developed in the second developer storage tank 207b. After stirring with a new developer having a high toner concentration sent from the agent storage tank 207a, the developer 208 having a high toner concentration is attracted (ie, pumped up) to the fixed magnetic pole n2 (the developer pumping pole). Then, the process proceeds to the fixed magnetic pole s1 (developer transport pole). The developer 208 having a high toner concentration transferred to the fixed magnetic pole s1 is transferred to the fixed magnetic pole n3 (developing pole) by the developer regulating member 205 with a constant amount.

  Further, the outer surface of the developing sleeve 202 is subjected to a well-known blasting process so that fine irregularities are formed, or the developing sleeve 202, that is, a groove extending along the axis 203 of the developer carrier 204. A plurality of may be formed.

Next, the developer stripping electrode plate provided in the developing device 2 of the present invention will be described.
The developer stripping electrode plate 212 (hereinafter referred to as an electrode plate) is formed of a nonmagnetic material such as aluminum or stainless steel, and is attached to the surface of the developing sleeve 202 of the developer carrying member 204 with a predetermined gap. . The position of the electrode plate 212 is the position opposed to the out-of-agent region r (that is, the position opposite to the out-of-agent electrode p) as shown in FIG. It is a place that does not.

  As described above, when the film thickness is increased in order to increase the life, the carrier has a high resistance. When this high-resistance carrier is used, after solid image development, the developer does not run out at the run-out portion, and the used developer is brought along with the developer carrying body, and the next after one developer carrying body. The phenomenon that the image density at the leading edge of the image becomes thin occurs. The mechanism of the high resistance carrier is as follows. Since the carrier after the development is deprived of the toner, a counter charge corresponding to the charge of the toner accumulates, and the Q / M increases. When Q / M increases, the image power increases, and the agent is taken out without running out of the agent.

  Therefore, in the present invention, the electrode plate 212 is disposed at a position facing the out-of-agent region r (that is, a position facing the out-of-agent electrode p), and the developer that has been electrostatically carried with the developer carrier 204 is removed. By applying a DC bias to the developer stripping electrode plate 212 of the present invention by the bias power source 213, an electric field (a carrier is transferred from the developer carrier 202 to the electrode plate 212) between the developer carrier 202 and the electrode plate 212. And the developer that has been carried away is peeled off from the developer carrier 204 by the electric field force, so that it can be prevented from being electrostatically carried.

If the carrier can be peeled off from the developer carrier 204, the position of the electrode plate 212 is not a problem even if it is other than the agent run-out region r (for example, the position facing the fixed magnetic poles n1 and n2 in FIG. 2). The reason why the present invention is specified as the place facing the out-of-agent region r is as follows.
In the out-of-agent region r, only the used developer is electrostatically carried with the developer carrier 204, and the toner concentration is low. However, in areas other than the out-of-agent area, both the agent used for development and the agent not used exist, and the toner concentration is high. In addition, since an electric field is formed between the developer carrying member 204 and the electrode plate 212 in the direction in which the carrier is peeled off from the developer carrying member 204, the electric field is applied in the direction in which the toner of reverse polarity is attracted to the developer carrying member 204. This is a direction in which the developing sleeve is contaminated due to toner adhesion. As a result, the developer sleeve is more likely to be smeared when the toner concentration is high. Therefore, the developer sleeve is not smudged when the electric field is formed in the portion where the toner concentration is as low as possible, and the developer that has been electrostatically carried away is also peeled off. Therefore, it is better to install and peel off the electrode plate 212 at a location facing the out-of-agent region r.

[Explanation of developer carrier]
Next, the relationship between the static electricity accompanying and the carrier resistance will be described.
FIG. 3 shows the relationship between the volume specific resistance of the carrier and the accompanying rank (visual rank evaluation of the developer accompanying the agent running-out portion). Rank 5 is a state where no developer is involved, and rank 1 is a state where a developer is so dense that the sleeve surface cannot be seen.
FIG. 3 shows that there is a correlation between the volume resistivity and the accompanying rank, and the higher the volume resistivity, the worse the accompanying property. The volume resistivity is 1 × 10 ^14.5 Ω · cm or more and rank 5 or less. From this, it can be seen that when a carrier having a volume resistivity of 1 × 10 ^14.5 Ω · cm or more is used, the carrier is accompanied, so that the carrier stripping effect of the present invention is great. Further, when the volume resistivity exceeds 1 × 10 ¹⁷ Ω · cm, the edge effect becomes too large, so that an image with an emphasized edge appears and becomes a problem.

  The volume resistivity is measured as follows. As shown in FIG. 4, a cell 133 made of a fluororesin container containing electrodes 132a and 132b having a distance between electrodes of 2 mm and a surface area of 2 × 4 cm is filled with a carrier 133, and a tapping machine PTM-1 (Sankyo Piotech) Tapping operation is performed for 1 minute at a tapping speed of 30 times / min. A DC voltage of 1000 V is applied between the two electrodes, the direct current resistance is measured by a high resistance meter 4329A (4329A + LJK5HVLVWDQFH OHWHU; manufactured by Yokogawa Hewlett-Packard Company), volume specific resistance R [Ω · cm] is obtained, and LogR is calculated.

  Further, since there is a possibility that electric discharge occurs between the electrode plate 212 and the developer carrier 204, the generation of electric discharge can be suppressed by insulating the surface of the electrode plate 212 facing the developer carrier 204. . As an insulating method, it is conceivable to apply an insulating tape or to perform an alumite treatment, but the insulating method is not limited.

  As described above, in the present invention, since an electric field that attracts toner toward the developer carrying member is applied, there is a concern about contamination of the developing sleeve 212 due to toner adhesion. Therefore, it is desirable to shorten the time during which the electric field is applied. Accordingly, the stain on the developing sleeve 212 can be minimized by applying a bias to the electrode plate 212 only during the developing operation (image formation).

[Description of developer toner]
Next, the toner suitably used in the developing device (and the process cartridge and the image forming apparatus) of the present invention will be described.
In order to reproduce fine dots of 600 dpi or more, the toner preferably has a volume average particle diameter of 3 to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.40. The closer (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

The toner shape factor SF-1 is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180. 5 and 6 are diagrams schematically showing the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2. The shape factor SF-1 indicates the ratio of the roundness of the toner shape, and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of a shape formed by projecting toner onto a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). This is a value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner onto the two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-2 = {(PERI) ² / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.

Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.
When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photosensitive member becomes a point contact, so that the adsorbing force between the toners becomes weak, and thus the fluidity becomes high. The attracting power with the body also becomes weaker, and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

  The toner suitably used in the developing device (and process cartridge and image forming apparatus) of the present invention contains at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent in an organic solvent. A toner obtained by subjecting a dispersed toner material liquid to a crosslinking and / or elongation reaction in an aqueous solvent. Hereinafter, the constituent material and the manufacturing method of the toner will be described.

[Component materials of toner]
(polyester)
The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound.
Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable. Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. The trihydric or higher polyhydric alcohol (TO) includes 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) with a small amount of (TC) Mixtures are preferred. Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

The polycondensation reaction between a polyhydric alcohol (PO) and a polycarboxylic acid (PC) is carried out in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and heated to 150 to 280 ° C. while reducing the pressure as necessary. The produced water is distilled off to obtain a polyester having a hydroxyl group. The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20. By giving an acid value, it tends to be negatively charged, and furthermore, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation.
The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.

In addition to the unmodified polyester obtained by the above polycondensation reaction, the polyester preferably contains a urea-modified polyester. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines.
Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.

  The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.

  The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates.

  The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

  Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).

  Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like. Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the compound (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

  The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.

  The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

  The urea-modified polyester is produced by a one-shot method or the like. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group. Subsequently, at 40-140 degreeC, this is made to react with polyvalent isocyanate (PIC), and the polyester prepolymer (A) which has an isocyanate group is obtained. Further, this (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a urea-modified polyester.

  When reacting (PIC) and when reacting (A) and (B), a solvent may be used if necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to isocyanates (PIC), such as tetrahydrofuran (such as tetrahydrofuran).

  In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

  The weight average molecular weight of the urea-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester or the like is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. When the urea-modified polyester is used alone, its number average molecular weight is usually 2000-15000, preferably 2000-10000, more preferably 2000-8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.

  By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the glossiness when used in a full-color image forming apparatus are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.

  The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition. The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, and particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient.
In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

(Coloring agent)
As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher , Yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Sayred, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Lid Russian nin green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.

  The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded together with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene or the like, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be mentioned, and these can be used alone or in combination.

(Charge control agent)
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salt or compound, tungsten simple substance or compound, fluorine activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo series Fee, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.

  The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction force between the developer carrying member and the developing sleeve is increased, and the flowability of the developer is reduced. This causes a decrease in image density.

(Release agent)
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. The effect on high temperature offset is exhibited without applying a release agent such as oil. Examples of such a wax component include the following. Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax, and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, And petroleum waxes such as petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. .
The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, and of course, they may be added when dissolved and dispersed in the organic solvent.

(External additive)
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × ¹⁰ -3 ~2μm, it is particularly preferably 5 × ¹⁰ -3 ~0.5μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5 wt% of the toner, and particularly preferably 0.01 to 2.0 wt%.

Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Among these, as the fluidity imparting agent, it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using particles having an average particle diameter of 5 × 10 ⁻² μm or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even when stirring and mixing inside the developing device is performed to obtain a good image quality that does not cause the release of the fluidity imparting agent from the toner and does not generate firefly, etc., and further reduces the residual toner. It is done.

  Titanium oxide fine particles are excellent in environmental stability and image density stability, but have a tendency to deteriorate the charge rise characteristics. Therefore, if the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, this side effect is affected. It can be considered large. However, when the addition amount of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles is in the range of 0.3 to 1.5 wt%, the charge rising characteristics are not significantly impaired and the desired charge rising characteristics can be obtained. That is, stable image quality can be obtained even when copying is repeated.

  Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.

[Toner Production Method]
(1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferable. The usage-amount of an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

(2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.
The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical.
Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.

  As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.

  Further, by using a surfactant having a fluoroalkyl group, the effect can be increased in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned.

  Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

  Moreover, as the cationic surfactant, aliphatic quaternary ammonium such as aliphatic primary, secondary or secondary amic acid, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt which has a right fluoroalkyl group is used. Salt, benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (manufactured by Asahi Glass), Florard FC-135 (manufactured by Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Smoke), Megafac F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footage F-300 (Neos), and the like.

The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao Corporation), SGP (manufactured by Soken Co., Ltd.), Techno Examples include polymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.).
In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

  As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Luric acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl Nitrogen compounds such as imidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, poly Xoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxy Polyoxyethylenes such as ethylene nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

(3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group.
This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

(4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. . Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by operations such as enzymatic degradation.

(5) A charge control agent is injected into the toner base particles obtained above, and then inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner.
The injection of the charge control agent and the external addition of the inorganic fine particles are performed by a known method using a mixer or the like.
Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

[Description of toner shape]
The toner according to the present invention has a substantially spherical shape and can be represented by the following shape rule.
FIG. 7 is a diagram schematically showing the shape of the toner used in the developing device of the present invention. In FIG. 7, when a substantially spherical toner is defined as a major axis r1, a minor axis r2, and a thickness r3, and r1 ≧ r2 ≧ r3, the toner of the present invention has a ratio (r2) of the major axis to the minor axis. / R1) is preferably 0.5 to 1.0 and the ratio of thickness to minor axis (r3 / r2) is preferably in the range of 0.7 to 1.0. When the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, the dot reproducibility and transfer efficiency are inferior because of being away from the true spherical shape, and high quality image quality cannot be obtained. On the other hand, if the ratio of thickness to minor axis (r3 / r2) is less than 0.7, the shape is close to a flat shape, and a high transfer rate like a spherical toner cannot be obtained. In particular, when the ratio of the thickness to the minor axis (r3 / r2) is 1.0, the rotating body has a major axis as a rotation axis, and the fluidity of the toner can be improved.
Note that r1, r2, and r3 were measured with a scanning electron microscope (SEM) while changing the angle of field of view and taking pictures.

Next, specific examples of the present invention will be further described.
Example 1
Images were developed under the conditions described below as development conditions. The developing device has the configuration shown in FIG. 2, and development was performed by the above-described operation. The developer 208 is a negatively charged toner, a carrier having a particle diameter of 35 μm and a carrier having a volume resistivity of 1 × 10 ¹⁵ Ω · cm, the diameter of the developing sleeve 202 of the developer carrier 204 is 18 mm, and the developing bias is DC-500V. The distance (development gap) between the developing sleeve 202 of the developer carrier 204 and the image carrier (photoreceptor) 1 is 0.3 mm, the developer pumping amount is 40 mg / cm ² , and the developer stripping electrode plate 212 and the developer are developed. The distance between the agent carriers 204 (the distance between the electrode plate 212 and the developing sleeve surface in the developer stripping region r) is 0.5 mm, the applied bias of the electrode plate 212 is −1000 V, and the width of the electrode plate 212 (development) The width in the rotation direction of the developer carrying member facing the agent carrying member 204 is 5 mm. Further, an insulating tape is applied to the surface of the electrode plate 212 facing the developer carrier 204 to insulate it. Although a solid image was output under the above conditions, there was no occurrence of uneven images due to the developer accompanying.

(Example 2)
Even when the volume specific resistance of the carrier is set to 1 × 10 ¹⁷ Ω · cm under the same conditions as in Example 1, there is no unevenness due to the developer accompanying the solid image, and the carrier resistance is high and the carrying is poor. It was confirmed that the effect was obtained even under the conditions.

(Example 3)
Even when the distance between the developer stripping electrode plate 212 and the developer carrier 204 is changed to 2 mm and the applied bias of the electrode plate 212 is changed to −2000 V under the same conditions as in the first embodiment, the solid image is accompanied by the developer. There is no density unevenness due to the above, and even if the distance between the electrode plate 212 and the developer carrier 204 is increased, the effect can be obtained by adjusting the electric field formed between the electrode plate 212 and the developer carrier 204. It was confirmed.

(Comparative example)
When an image was printed under the same conditions as in Example 1 except that only the developer stripping electrode plate 212 was removed, density unevenness due to rotation of the developer occurred in the solid image.

  As described above, in the developing device 2 of the present invention, the out-of-agent region r where the developed developer having a low toner concentration is dropped from the developing sleeve 202 into the developer containing tank 207b is removed from the developing sleeve 202. In addition to providing an out-of-agent electrode p on the surface of the magnet roller 201 so as to be formed on the surface, the electrode plate is located at a position facing the out-of-agent electrode p (a position facing the out-of-agent electrode p near the surface of the developing sleeve 202). 212 is arranged, a bias is applied to the electrode plate 212, and an electric field in a direction in which the carrier is peeled off from the developer carrier 204 (an electric field in a direction in which the carrier moves from the developer carrier 204 to the electrode plate 212) is formed. By adopting the configuration, the developer that has been taken away can be peeled off from the developer carrying member 204 by the force of an electric field, so that it is not taken electrostatically. Since it can be high-carrier resistance associated with high life of the developer is prevented electrostatic bring about the cause. Therefore, according to the present invention, it is possible to realize the developing device 2 that can achieve both a long life of the developer and high-quality development (image formation) without image density unevenness. By using the developing device 2, high-quality image formation without image density unevenness can be performed, and an image forming apparatus can be realized.

1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. 1 is a schematic cross-sectional view of a developing device showing an embodiment of the present invention. It is a figure which shows the relationship between the volume specific resistance of a carrier, and the accompanying rank (those which carried out visual rank evaluation of the developer accompanying the agent running-out part). It is a perspective view which shows the cell used for the measurement of the volume specific resistance of a carrier. FIG. 4 is a diagram schematically illustrating the shape of a toner in order to explain the shape factor SF-1. FIG. 6 is a diagram schematically illustrating the shape of a toner in order to explain the shape factor SF-2. FIG. 3 is a diagram schematically showing the shape of toner used in the developing device of the present invention. It is a schematic sectional drawing of the image development apparatus which shows an example of a prior art. It is a schematic sectional drawing of the image development apparatus which shows another example of a prior art. It is sectional drawing which follows the abcd line in FIG.

Explanation of symbols

1 (1Y, 1C, 1M, 1K): photoconductor (image carrier)
2 (2Y, 2C, 2M, 2K): developing device 3Y, 3C, 3M, 3K: charging device 4: exposure device (latent image forming means)
6: Transfer device 7Y, 7C, 7M, 7K: Photoconductor cleaning device 10: Intermediate transfer belt (intermediate transfer member)
11, 12, 13: Support rollers 14Y, 14C, 14M, 14K: Primary transfer roller 15: Belt cleaning device 16: Secondary transfer roller 20: Paper feed cassette 21: Paper feed roller 22: Registration roller pair 23: Heat fixing device 24: paper discharge roller 30: image forming unit 31Y, 31C, 31M, 31K: toner bottle 201: magnet roller (magnetic field generating means)
202: Development sleeve (hollow body)
203: shaft 204: developer carrier 205: developer regulating member 206: stirring member 206a: first stirring screw 206b: second stirring screw 207: developer storage tank 207a: first developer storage tank 207b: second development Agent storage tank 208: Developer 212: Electrode plate 213: Power supply for bias

Claims (12)

A cylindrical or columnar magnetic field generating means having a plurality of fixed magnetic poles on the surface portion, and a rotatable nonmagnetic material disposed coaxially with the axis of the magnetic field generating means so as to enclose the magnetic field generating means A developer carrying member for developing an electrostatic latent image on the image carrier by carrying and conveying a developer comprising toner and a carrier,
A developer regulating member that is provided so as to face the developer carrying member and regulates the amount of developer carried on the developer carrying member and conveyed to the image carrier;
A stirring member that is provided upstream of the developer regulating member in the rotation direction of the developer carrying member, and that conveys the developer contained in the developer containing tank in the axial direction of the hollow body;
In a developing device having at least
In the surface portion of the magnetic field generating means, an agent breakage pole is formed on the outer surface of the hollow body so as to form an agent breakage region for dropping the developed developer having a low toner concentration from the hollow body into the developer accommodating tank. And an electrode plate disposed at a position opposite to the agent breakage pole, a bias is applied to the electrode plate, and an electric field is formed in a direction in which the carrier is peeled off from the developer carrier. A developing device. The developing device according to claim 1,
The developing device, wherein the carrier used for the developer has a volume resistivity of 1 × 10 ^14.5 Ω · cm or more and 1 × 10 ¹⁷ Ω · cm or less. The developing device according to claim 1 or 2,
At least a surface of the electrode plate facing the developer carrying member is insulated. The developing device according to any one of claims 1 to 3,
A developing device that applies a bias to the electrode plate only during image formation. In the developing device according to any one of claims 1 to 4,
The toner used for the developer has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of 1.00 to 1.n. A developing device in the range of 40. In the developing device according to any one of claims 1 to 5,
The developing device according to claim 1, wherein the toner used in the developer has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. In the developing device according to any one of claims 1 to 6,
The toner used in the developer is formed by crosslinking a toner material solution in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent in an aqueous medium. And / or a developing device obtained by an extension reaction. In the developing device according to any one of claims 1 to 7,
The developing device according to claim 1, wherein the toner used for the developer has a substantially spherical shape. In the developing device according to any one of claims 1 to 7,
The toner used in the developer is defined by a major axis r1, a minor axis r2, and a thickness r3. When r1 ≧ r2 ≧ r3, the ratio of the major axis r1 to the minor axis r2 (r2 / r1) is in the range of 0.5 to 1.0, and the ratio of the thickness r3 to the minor axis r2 (r3 / r2) is in the range of 0.7 to 1.0. In the process cartridge equipped in the image forming unit of the image forming apparatus,
A process cartridge comprising at least an image carrier and the developing device according to claim 1, wherein the process cartridge is detachably attached to an image forming apparatus main body. An image carrier, charging means for charging the image carrier, means for forming an electrostatic latent image on the image carrier, and developing means for developing and developing the latent image on the image carrier. In an image forming apparatus comprising at least
An image forming apparatus comprising the developing device according to claim 1 as the developing unit. In an image forming apparatus comprising at least an image carrier, a means for forming an electrostatic latent image on the image carrier, and a developing means for developing and developing the latent image on the image carrier.
An image forming apparatus comprising the process cartridge according to claim 10.

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