JP2006293261A - Developing apparatus, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly and surely peel and remove residual developer with image hysteresis on a developing sleeve after passing through a developing area. <P>SOLUTION: Regarding a developing apparatus, a developing roller constituted of a rotatable non-magnetic sleeve and a magnetic field generating means fixedly arranged in the sleeve and with a plurality of magnetic poles are arranged in the flank of a latent image carrier, and two-component developer drawn up to the sleeve surface is fed upward from beneath by rotating the sleeve counterclockwise, and then, the developer as a magnetic brush is made to rub the latent image carrier (40) in a developing area from the 4th quadrant to the 1st quadrant of the developer roller cross section by regarding the rotational center of the sleeve as an origin of vertical plane coordinates, so that the latent image on the latent image carrier is developed, and in order to peel the developer from the sleeve surface on the downstream side in the rotating direction of the sleeve, the developing apparatus is constituted so that the developer peeling pole (2d) may have the same magnetic polarity as that of the magnetic pole positioned on the downstream side of the developer peeling pole (2d), and the developer peeling pole (2d) is positioned in the 2nd quadrant of the developer roller cross section, and a magnet (7) is arranged outside in the radial direction of the sleeve to face the developer peeling pole (2d), the side facing the peeling pole (2d) has the same polarity as that of the peeling pole (2d). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus for forming an image by electrophotography, magnetic recording, etc., such as a copying machine, a facsimile machine, a printer, etc., in particular, a two-component developing type developing apparatus used for such an image forming apparatus, or its development The present invention relates to a process cartridge provided with an apparatus.

JP 7-13435 A Japanese Patent No. 3237940

  In an image forming apparatus such as an electrophotographic copying apparatus, an electrostatic recording apparatus, or a magnetic recording apparatus, a magnetic brush system is known for developing an electrostatic latent image formed on an image carrier. This is because a developer is magnetically carried on a non-magnetic cylinder (developing sleeve) which is a developer carrying member rotatably attached to a developing device casing or the like, and a developing region (developer carrying member and image is conveyed). A developer magnetic brush is formed in a region where a developable electric field is ensured between the carriers (heading) and rubbed against the image carrier (photoreceptor) to cause electrostatic latent image on the image carrier. The image is visualized. Therefore, a plurality of magnets are arranged in a fixed state in the developing sleeve (in some cases, a so-called plastic magnet kneaded with plastic resin may be oriented by applying a magnetic field during molding to obtain a necessary magnetic pole distribution) The developer is conveyed by rotating. One of the plurality of magnetic poles arranged in the developing sleeve is a developing magnetic pole arranged at a position facing the surface of the image carrier on which the electrostatic latent image is formed, and the other is a developer via the developing sleeve. Are a plurality of conveying magnetic poles and pumping magnetic poles.

  Patent Document 1 discloses such a two-component developing type developing apparatus. In the developing device, a magnet is arranged inside a rotatable developing sleeve. Among the magnetic poles of the magnet, the same-polarity conveying magnetic poles N2 and N3 are disposed adjacent to the developing container side. After the development, it is necessary to quickly remove the residual developer on the developing sleeve so that the surface of the developing sleeve can be used for the next developing process, but a repulsive magnetic field is formed between the magnetic poles N2 and N3. Therefore, the developer composed of hard magnetic particles and toner tends to stay in the vicinity of the upstream magnetic pole N2. Therefore, in Patent Document 1, the developer peeling means is arranged to face the magnetic pole N2. This developer peeling means has a rotating shaft and a blade member, and is configured to peel and stir the developer by rotating in a predetermined direction.

  However, the method of having the rotating shaft and the blade member in the vicinity of the developer peeling portion in this way and mechanically peeling the developer from the developer carrier gives stress to the developer and shortens the developer life. In addition, due to the recent demands of users, it is necessary to make the entire machine compact and to reduce the size of the developing device itself. On the other hand, in the above method, the construction of the developing device becomes complicated and large. There is a drawback.

  As another method for peeling the developer from the developing sleeve, the magnetic force is partially brought close to 0 mT by the repelling electric field of the developer peeling pole and the magnetic pole of the same polarity adjacent thereto at the developer peeling portion of the developing sleeve. It is conventionally known that the developer cannot be held on the developer sleeve and the developer is separated from the developing sleeve. However, in such a method, the remaining developer having an image history stays in the developer peeling portion due to the repulsive electric field of the adjacent magnetic pole having the same polarity. The image history means the process of forming an image and a non-image on the electrostatic latent image carrying surface of the image carrier. For the image portion, the developer (toner) on the developing sleeve is consumed at the developing position. For the portion, the developer (toner) is not consumed and remains on the developing sleeve as it is. When the developer stays, the amount of the developer that can be used for development on the developing sleeve is reduced, stress is given to the developer, and the life of the developer is also affected. As a result, it leads to deterioration of image quality such as a decrease in image density.

  In Patent Document 2, in order to improve the developer peeling performance after contributing to the development, the upper end of the vertical portion of the guide member is made to face the downstream magnetic pole in the developing sleeve rotation direction among adjacent pairs of the same polarity magnetic poles. It has been proposed that the ends of the guide member are opposed to each other between a pair of magnetic poles having the same polarity, and a developer curtain is formed by the generated magnetic force to separate the developer from the developing sleeve. In this proposed configuration, the developer staying on the upstream side in the rotation direction cannot be removed. Therefore, the staying developer is smoothly peeled off, so that there is no effect of improving the life of the developer.

  SUMMARY OF THE INVENTION An object of the present invention is to make it possible to quickly and reliably peel and remove a residual developer having an image history on a developing sleeve after passing through a developing region.

  In order to solve the above problems, according to the present invention, a developing roller comprising a rotatable nonmagnetic sleeve and a magnetic field generating means having a plurality of magnetic poles fixedly arranged in the sleeve is disposed on the side of the latent image carrier. A developing roller as a magnetic brush by feeding the two-component developer pumped from the bottom to the sleeve surface by rotating the sleeve counterclockwise with the rotation center of the sleeve as the origin of the vertical plane coordinate system. The latent image on the latent image carrier is visualized by sliding on the latent image carrier in the development region from the fourth quadrant to the first quadrant of the cross section, and the developer is removed from the sleeve surface on the downstream side of the sleeve rotation. In the developing device configured such that the developer peeling pole and the magnetic pole on the downstream side thereof have the same magnetic characteristics to be peeled off, the developer peeling pole is located in the second quadrant in the cross section of the developing roller. Opposite A magnet disposed in the sleeve radially outward that the side facing the separating pole is the separating pole the same polarity. Further, the developer peeling pole is located in the second quadrant in the cross section of the developing roller, a magnet is arranged on the outer side in the radial direction of the sleeve facing the developer peeling pole, and the surface closest to the developing sleeve of the magnet is non-magnetized. The above problem can also be solved by arranging the developer stripping pole and the same polarity magnetic pole on the downstream side of the magnet sleeve rotation, and the remaining developer that tends to stay due to the repulsive electric field of the adjacent magnetic pole of the same polarity can be peeled off satisfactorily. As a result, the developer life can be extended without applying unnecessary stress to the developer. “Quadrant” is generally used as a mathematical terminology. As shown in FIG. 13, when a parallel coordinate system is defined on a plane, the plane is divided into four parts by coordinate axes (orthogonal axes and oblique axes). Divided into the first, second, third, and fourth quadrants in order counterclockwise from the upper right portion. The essence of the present invention is that development is performed by rubbing a magnetic brush against the latent image carrier in the development region from the fourth quadrant to the first quadrant of the developing roller cross section with the rotation center of the sleeve as the origin of the vertical plane coordinate system. In this case, the developer peeling pole is positioned in the second quadrant in the cross section of the developing roller, and the opposing magnetic pole is made the same pole. When the latent image carrier is located on the left side of the developing sleeve and the magnetic brush moves from bottom to top and rubs against the latent image carrier for development, the mirror image relation is established, and the sleeve is The development area is in the third quadrant to the second quadrant, the developer peeling pole is located in the first quadrant on the cross section of the developing roller, and the opposing magnetic poles are the same pole. Is essentially the same.

  It is preferable that the magnetic flux density of the magnet arranged outward in the sleeve radial direction is at least the same as the magnetic flux density of the developer peeling pole. In particular, the magnetic flux density of the magnet disposed outward in the sleeve radial direction is preferably 5 times or less than the magnetic flux density of the developer peeling pole. When the side facing the peeling surface is the same pole, the magnet arranged outward in the sleeve radial direction is within an angle range between the developer peeling pole and the pole on the upstream and downstream sides of the sleeve rotation of the peeling pole. It is convenient to be. When the surface closest to the developing sleeve is non-magnetized and the same polarity magnetic pole as the developer peeling pole is arranged on the downstream side of the rotation of the sleeve of the magnet, the magnet arranged outward in the sleeve radial direction is the developer peeling pole. It is advantageous that the angle range is from the top of the sleeve rotation upstream side to the peeling pole. It is reasonable that the magnet disposed radially outward of the sleeve is disposed on the developing casing wall.

  According to the present invention, with the rotation center of the developing sleeve as the origin of the vertical plane coordinate system, the two-component developer pumped up to the sleeve surface by rotating the sleeve counterclockwise is sent from below to above as a magnetic brush, and the developing roller The latent image on the latent image carrier is visualized by sliding on the latent image carrier in the development region from the fourth quadrant to the first quadrant of the cross section, and the developer is removed from the sleeve surface on the downstream side of the sleeve rotation. In the developing device configured such that the developer peeling pole and the magnetic pole on the downstream side thereof have the same magnetic characteristics to be peeled off, the developer peeling pole is located in the second quadrant in the cross section of the developing roller. A magnet is arranged on the outer side of the sleeve in the radial direction of the sleeve, and the side facing the peeling pole is the same as the peeling pole, or the surface closest to the developing sleeve of the magnet is non-magnetized, and the magnet sleeve rotates downstream. Developer peeling electrode on the side Since the same magnetic pole is arranged, the remaining developer that tends to stay due to the repulsive electric field between the developer peeling pole and the same polarity magnetic pole on the downstream side of the sleeve rotation can be peeled off and removed, resulting in unnecessary stress on the developer. As a result, the developer life can be extended. .

  If the distance between the developing sleeve and the developing casing wall is shortened and reduced, the developing device can be made compact. However, if the distance from the developing sleeve surface on the developer peeling pole to the developing casing is too close, the developer is peeled off. Therefore, the tendency for the developer to follow the developing sleeve is increased. In the conventional configuration, when the closest distance from the surface of the developing sleeve on the developer peeling pole to the developing sleeve wall is about 10 mm, the accompaniment frequently occurs due to the developing casing wall being too close. However, as in the present invention, by disposing the counter magnetic pole outside the developer peeling pole, even if the closest distance from the developing sleeve surface on the developer peeling pole to the developing casing wall is 10 mm or less, the developer Therefore, the developer can be transported without delay.

Embodiments in which the present invention is applied to an image forming apparatus will be described below.
FIG. 1 shows an electrophotographic full-color printer as an image forming apparatus according to this embodiment. An image unit 10 of the printer includes an intermediate transfer belt 11 as an image carrier that moves endlessly in the direction of an arrow. Four image forming units, which are toner image forming means, are provided on a lower stretched surface of the intermediate transfer belt 11. 12Y, 12C, 12M, and 12K are arranged. Y, C, M, and K along the number of the image forming unit correspond to the color of the toner to be handled, Y means yellow, C means cyan, M means magenta, and K means black. Similarly, Y, C, M, and K are provided along the photoreceptor 40 that is provided in the image forming unit and rotates together with the intermediate transfer belt 11. The photoconductors 40Y to 40K are arranged at equal intervals so as to be in contact with a part of a stretched portion with the intermediate transfer belt 11 at least during image formation.

  Although the toner colors to be handled are different, the image forming units 12Y, 12C, 12M, and 12K have the same configuration, and the configuration will be described as the image forming unit 12 with reference to FIG. In FIG. 2, a cylindrical photosensitive member 40 supported to rotate in the direction of the arrow by a drive source (not shown) during operation of the printer is disposed. Around the photosensitive member 40, an image forming member such as a charging unit, an exposure device, a developing device 1, a cleaning device, and a light neutralizing device, an electric potential sensor, and an image sensor are arranged in accordance with an electrophotographic process. Since the configuration and operation of the are basically known, for the sake of simplification of description, portions particularly related to the present invention will be described here.

  An electrostatic latent image is formed on the surface of the uniformly charged photoreceptor 40 by exposure based on image information. This electrostatic latent image is developed by the developing device 1 to form a toner image on the surface of the photoreceptor. The toner image is transferred to the intermediate transfer belt 11 (FIG. 1) by the transfer charger 13. The yellow (Y), cyan (C), magenta (M), and black (K) color toner images transferred to the intermediate transfer belt 11 are superimposed and fed from the paper feed unit 14 (FIG. 1) to the paper feed rollers and registration rollers. The image is transferred using a secondary transfer roller 15 onto the sheet conveyed through the pair. After the transfer, the toner image is fixed by the fixing unit 16 and is discharged out of the apparatus as it is in the case of single-sided image formation. In the case of double-sided image formation, a reversing path (not shown) is known. Through the double-sided portion (not shown), and again sent to the secondary transfer unit.

  In this embodiment, at least the photosensitive member 40 and the developing device 1 constitute a cartridge unit, and a process cartridge can be constituted by further including a charging device, a cleaning unit, and a charge eliminating device. When referred to as a process cartridge, the developing device and other process means are integrated and detachable, and the cartridge unit alone can be a process cartridge, or the developing device, the photosensitive member, the charging device, and the developing device. There can be various variations such as a photoreceptor, a charging device, and a cleaning device.

  Next, the overall configuration of the developing device according to the present embodiment will be described. In FIG. 2, the developing device 1 is disposed on the side of the photosensitive drum 40, and the developing roller 2 partially exposed from the opening formed on the photosensitive drum 40 side of the developing casing is provided around the photosensitive drum 40. In the direction, the photosensitive drum 40 is arranged in parallel and facing the photosensitive drum 40 with a certain gap. The developing sleeve 2a of the developing roller is made of a non-magnetic cylindrical member such as aluminum as a developer carrying member carrying a two-component developer composed of magnetic toner and a magnetic carrier on its surface. In the developing region facing the photosensitive drum 40, the developer can be driven to rotate in a direction to move the developer upward.

  The developing device 1 also includes a doctor blade 4 as a developer regulating member that regulates the amount of developer carried on the developing sleeve and conveyed toward the developing region, and agitation for mixing and conveying the developer in the developing casing. Screw rollers 5 and 6 and a T sensor for measuring toner density in the developing casing and supplying toner from the toner hopper are provided.

  Inside the developing roller 2, a magnet roller as a magnetic field generating means is fixedly arranged. A magnet roller is formed by embedding a plurality of magnet blocks in a plastic roller. Extrusion molding is performed while applying a magnetic field to a so-called plastic magnet or rubber magnet in which magnetic powder is dispersed and kneaded into plastic resin powder (polymer compound). Alternatively, it can be obtained by injection molding and then embedding a magnet block in the developing electrode portion. The magnet roller forms a 6-pole magnetic pole as in the illustrated example (there are 5 magnets but is generally referred to as a 6-pole magnetic pole), but may be configured with 8 or 10 poles as required. .

  Regarding the magnetic pole arrangement of the developing roller 2, the developing magnet 2 b (S pole in the illustrated example) is located at the closest position of the normal photosensitive member in the vicinity of the closest position between the developing roller 2 and the photosensitive member 40, or several degrees more than that. Arranged upstream. In the case of a two-component development system, a cycle in which a low toner content developer after developing the photosensitive drum 40 and consuming toner is released in a developing device (casing), and the stirred developer is pumped up again by a roller. Is repeated. Therefore, the developer is peeled (released) further downstream of the magnet 2c on the downstream side of the developing pole, and the peeling magnet 2d and the magnet 2e on the further downstream side have the same magnetic characteristics. The developer is pumped up at 2e, the thickness of the developer is regulated by the doctor blade 4 facing the magnet 2f, and the developer is conveyed to the development area.

  When there is no magnet at the position close to the peeling magnet 2d as in the conventional configuration, as shown in FIG. 3, a spike of developer is formed on the upstream side of the sleeve rotation of the peeling magnet 2d by the magnetic lines of force of the magnets 2c and 2d. Further, since the end of the peeling magnet 2d is close to the sleeve 2a, a state occurs in which the developer is held on the downstream side of the sleeve rotation of the magnet 2d by the magnetic lines of force of the peeling magnet 2d, and the developer stays in the range of the peeling magnet 2d. The flow of the developer is not smooth, which stresses the developer and shortens the life.

  In the case of the present embodiment, the magnet 7 facing the peeling magnet 2d on the outer side in the radial direction of the sleeve and disposed on the outer wall of the developing casing directs the magnetic pole having the same polarity as the peeling magnet 2d toward the peeling magnet. By disposing on the outer wall of the casing, the developer can be prevented from coming into direct contact with the counter magnet 7, and the same performance as the initial state can be exhibited over time. Incidentally, the position of the peeling magnet 2d facing the counter magnet 7 which is the developer peeling accelerating magnetic pole is the development pumped up by turning the developing sleeve counterclockwise with the rotation center of the developing sleeve 2a as the origin of the vertical plane coordinate system. When the agent is rubbed against the opposing photosensitive member from the fourth quadrant to the first quadrant of the developing roller cross section, it exists in the second quadrant. The magnet 7 generates a repulsive magnetic field with respect to the peeling magnet 2d, and uses the action to promote the peeling of the developer from the developing sleeve, so that the developer naturally falls by gravity. Since it is assumed that the peeling magnet 2d is disposed at a position where no demagnification can be expected, the peeling magnet 2d may be shifted to the first quadrant. Therefore, it is not limited to the second quadrant in a geometrically strict sense, and the region from the first quadrant to the second quadrant should be understood as the range of the second quadrant in the present invention. When the peeling magnet 2d is opposed to the first quadrant side, it can be shifted to the first quadrant side as well. However, as will be described later, the peeling magnet 2d is located in the second quadrant. However, even if a peel-promoting magnet is placed near the center between the poles on the upstream side of the sleeve rotation from the peeling pole (just in the middle between the poles), the peeling-promoting effect is recognized, so peeling The promotion magnet 7 can be disposed in a wider angle range than the peeling magnet 2d.

  The function of the counter magnet 7 which is the developer peeling accelerating magnetic pole will be described by showing the magnetic flux density distribution. FIG. 4 is a magnetic force graph of a conventionally known 6-pole configuration without the counter magnet 7. The horizontal axis indicates the angular position that rotates counterclockwise from the closest position of the developing roller and the photoreceptor (unit: degree), and the vertical axis indicates the magnetic force at a height of 1 mm from the developing sleeve (unit: Tesla). . The peeling magnet 2d exists at a position of approximately 120 °. FIG. 5 shows a magnetic force graph of the configuration according to this example in which the peeling promoting magnet 7 is disposed at a position 6 mm from the developing sleeve at the facing position. As the peeling promotion magnet 7, a magnet having a cross section of 4 mm × 3 mm and a magnetic force of 80 mT is used. With such a peeling promoting magnet 7, the normal component is weak (about 20 mT) and the tangential component is strong at the peeling magnetic pole. From comparison between FIG. 4 and FIG. 5, the heading of the peeled magnetic pole upstream of the sleeve rotation is directed to the tangential direction because a magnetic flux density cannot be generated in the normal direction by installing a peel promoting magnet. The heading downstream of the rotation cannot be made in the normal direction, and the head extends obliquely downward to the left of the figure. At this time, the magnetic field does not spread and is directed in a certain direction. The image is shown in FIG. The magnetic lines of force that form developer spikes on the upstream side in the sleeve rotation direction on the peeling magnet 2d are forcibly pressed against the development sleeve 2a, so that the developer spikes are not formed. This reduces the amount of developer that remains. Further, the end magnetic field lines of the peeling magnet 2d holding the developer carried by the sleeve rotation downstream of the peeling magnet 2d in the rotation direction of the developing sleeve 2a are forcibly directed in the rotation direction of the developing sleeve 2a. The developer staying at the end is reduced (see FIG. 7). That is, it can be said that the repulsive magnetic pole is placed at the position opposite to the separation pole, so that the magnetic field does not spread and is restricted in a certain direction.

  In this example, the magnetic flux density of the separation promoting magnet 7 is 80 mT, which is the same as that of the separation magnetic pole, whereby the magnetic flux density of the separation magnetic pole is attenuated by 20 mT, and the developer separation is promoted on the downstream side of the sleeve rotation from the separation pole. be able to. It is considered that when the peeling promoting magnet 7 is 160 mT, the magnetic flux density on the developing sleeve is close to 0 mT, and when it is further increased, the developer will fly toward the opposite magnetic pole. When the opposing magnetic pole has a magnetic flux density 6 times that of the peeling pole, the magnetic flux density in the normal direction reaches up to +40 mT, and the polarity is opposite to that of the configuration without the peeling promoting magnet, and the developer is peeled off from the developing sleeve. However, there is a problem that the developer is adsorbed on the counter magnetic pole. Therefore, the magnetic flux density of the counter magnetic pole should be about 5 times or less than the developer peeling magnetic pole.

  Further, according to the confirmation with an actual machine, if the peeling promoting magnet 7 is in an angle range between the peeling pole 2d and the poles 2c and 2e before and after the peeling pole, an effect on the developer peeling promoting effect is recognized. This is probably because the magnetic flux density in the tangential direction is high. When the peeling promoting magnet was disposed at a position exceeding the above-mentioned distance between the electrodes, the normal component increased as the magnetic flux density, the developer started to rise, and it was impossible to expect contribution to the developer peeling.

  Next, another embodiment of the present invention will be described. The present embodiment shown in FIG. 8 is different from the first embodiment shown in FIG. 2 only in the point of the magnet disposed outward of the sleeve radius facing the peeling magnet 2d. Therefore, the same portions as those described in the first embodiment of FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  In the case of this embodiment, the magnet 27 is arranged on the outer wall of the developing casing radially outward from the peeling magnet 2d, the surface closest to the developing sleeve is a non-magnetized surface, and the magnet 27 A magnetic pole having the same polarity as the peeling magnet 2d is provided on the downstream surface in the sleeve rotation direction.

  By disposing on the outer wall of the casing, the developer can be prevented from coming into direct contact with the opposing magnet 27, and the same performance as the initial state can be exhibited over time. The position of the peeling magnet 2d facing the counter magnet 27, which is the developer peeling accelerating magnetic pole, is the same as in the first embodiment, and the rotation center of the developing sleeve 2a is the origin of the vertical plane coordinate system. When the developer pumped up by turning the developing sleeve counterclockwise is rubbed against the opposing photosensitive member from the fourth quadrant to the first quadrant of the developing roller, the second quadrant exists. The magnet 27 generates a repulsive magnetic field with respect to the peeling magnet 2d, and uses its action to promote the peeling of the developer from the developing sleeve, so that the developer naturally falls by gravity. Since it is assumed that the peeling magnet 2d is disposed at a position where no demagnification can be expected, the peeling magnet 2d may be shifted to the first quadrant. Therefore, it should be understood that the range from the first quadrant to the second quadrant is not limited to the second quadrant in a geometrically strict sense, but is also a range of the second quadrant. When the peeling magnet 2d is shifted to the first quadrant side, the opposing peeling promoting magnet 27 can be shifted to the first quadrant side accordingly, but even if the peeling magnet 2d is located in the second quadrant, the peeling pole 2 Even if the peeling accelerating magnet 27 is disposed near the position on the upstream side of the sleeve rotation upstream, the peeling accelerating effect is recognized. Therefore, the peeling accelerating magnet 27 can be arranged in a wider angle range than the peeling magnet 2d. is there.

  A magnetic force graph of the configuration according to the present embodiment is shown in FIG. From the comparison between FIG. 5 and FIG. 9, the peeling promoting magnet 27 of this embodiment makes the normal component in the peeling magnetic pole weaker than that in the first embodiment (about 15 mT), and the tangential component is stronger than in the first embodiment ( 20mT). Due to the peeling promoting magnet 27 of this embodiment, the rising of the peeling magnetic pole upstream of the sleeve rotation is more difficult in the normal direction than in the case of the first embodiment by installing the peeling promoting magnet, and is more suitable in the tangential direction. ing. The image is shown in FIG. The magnetic lines of force that form developer spikes on the upstream side in the sleeve rotation direction on the peeling magnet 2d are forcibly pressed against the development sleeve 2a, so that the developer spikes are not formed. This reduces the amount of developer that remains. Further, the separation magnet 2d is forced to direct the end magnetic field lines of the peeling magnet 2d itself holding the developer carried by the sleeve rotation to the downstream side in the rotation direction of the developing sleeve 2a of the peeling magnet 2d, thereby forcibly directing the developing magnet 2d in the rotation direction of the developing sleeve 2a. The developer staying at the end of the toner is further reduced (see FIG. 11). In addition, the separation promoting magnet 27 of the present embodiment has a wider range that can be installed with respect to the sleeve rotation upstream than the case of the first embodiment, and can be installed up to the conveying magnetic pole 2c. Is also achieved (see FIG. 12). When the developer that rises in the vicinity of the transport magnetic pole 2c installs the separation promoting magnet 27, the magnetic flux density in the normal direction is lowered, and the magnetic flux density is directed in the tangential direction, so that the developer is transported smoothly. This is probably because the magnetic flux density in the tangential direction is high.

  In this embodiment, the magnetic flux density of the separation promoting magnet 27 is the same as that of the separation magnetic pole, and is 80 mT. Thus, the magnetic flux density of the separation magnetic pole is attenuated by 15 mT from the first embodiment. Agent peeling can be promoted. It is considered that when the peeling promoting magnet 27 is 160 mT, the magnetic flux density on the developing sleeve is close to 0 mT, and when it is further increased, the developer flies toward the opposite magnetic pole. When the opposing magnetic pole has a magnetic flux density 6 times that of the peeling pole, the magnetic flux density in the normal direction reaches up to +40 mT, and the polarity is opposite to that of the configuration without the peeling promoting magnet, and the developer is peeled off from the developing sleeve. However, there is a problem that the developer is adsorbed on the counter magnetic pole. Therefore, the magnetic flux density of the counter magnetic pole should be about 5 times or less than the developer peeling magnetic pole.

  Further, according to the confirmation with an actual machine, if the peeling promoting magnet 27 is in an angle range from the transport pole 2c before the peeling pole 2d to the top of the peeling pole 2d, an effect on the developer peeling promoting action is recognized. This is probably because the magnetic flux density in the tangential direction is high. When the peeling promoting magnet was disposed at a position exceeding the above-mentioned distance between the electrodes, the normal component increased as the magnetic flux density, the developer started to rise, and it was impossible to expect contribution to the developer peeling.

  Next, the toner suitably used in the image forming apparatus of the present invention will be described. In order to reproduce minute dots of 600 dpi or more, the toner preferably has a weight average particle diameter of 3 to 8 μm. In this range, since the toner particles have a sufficiently small particle size with respect to the minute latent image dots, the dot reproducibility is excellent. When the weight average particle diameter (D4) is less than 3 μm, phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties tend to occur. When the weight average particle diameter (D4) exceeds 8 μm, it is difficult to suppress scattering of characters and lines.

  The ratio (D4 / D1) of the weight average particle diameter (D4) to the number average particle diameter (D1) is preferably in the range of 1.00 to 1.40. The closer (D4 / D1) 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.

  Next, a method for measuring the particle size distribution of toner particles will be described. As an apparatus for measuring the particle size distribution of toner particles by the Coulter counter method, there can be mentioned Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below.

  First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of an aqueous electrolytic solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the weight and number of toner particles or toner using a 100 μm aperture as an aperture. Calculate weight distribution and number distribution. From the obtained distribution, the weight average particle diameter (D4) and the number average particle diameter (D1) of the toner can be obtained.

  As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Uses 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.

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. 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 the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4. 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.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π. 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.
SF-2 = {(PERI) ² / AREA} × (100 / 4π) (2)

  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 toner shape is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak, and thus the fluidity becomes high, and the toner and the photoconductor The adsorbing power of the ink becomes weak and the transfer rate becomes high. 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 image forming apparatus of the present invention includes a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent are dispersed in an organic solvent. A toner obtained by crosslinking and / or elongation reaction in an aqueous solvent. Hereinafter, the constituent material and the manufacturing method of the toner will be described.

(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 polyester prepolymer is reacted with amines at 0 to 140 ° C. to obtain a urea-modified polyester.

  When reacting PIC and when reacting the polyester prepolymer and amines, 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 gloss when used in the full-color image forming apparatus 100 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 salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. 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 with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

(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 added 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 greatly impaired, and the desired charge rising characteristics can be obtained, that is, repeated copying. Stable image quality can be obtained even if

  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 obtained 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 (Asahi Glass Co., Ltd.), Florard FC-135 (Sumitomo 3M Co., Ltd.), 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), SGP (manufactured by Soken), 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 Bodies 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, a high-speed shearing type 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.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a main configuration of a developing device. It is a figure explaining the magnetic force line and the adhesion state of a developer when there is no magnet in the opposing proximity position of a peeling magnet. It is a magnetic force graph of a conventionally well-known 6-pole structure without a peeling promotion counter magnet. It is a magnetic force graph in the structure concerning a 1st embodiment. It is a figure which shows the image of the magnetic field in the peeling pole by presence of the peeling promotion opposing magnet which concerns on 1st Embodiment. It is a figure which shows a mode that the developer staying around a peeling magnet reduces by presence of the peeling acceleration | stimulation opposing magnet which concerns on 1st Embodiment. It is the schematic which shows the main structures of the developing device which concerns on another embodiment. It is a magnetic force graph in the structure concerning 2nd Embodiment. It is a figure which shows the image of the magnetic field in the peeling pole by presence of the peeling promotion opposing magnet which concerns on 2nd Embodiment. It is a figure which shows a mode that the developer which retains in a peeling magnet periphery reduces by presence of the peeling acceleration | stimulation opposing magnet which concerns on 2nd Embodiment. It is a figure which shows a mode that the developer which retains in the periphery of a peeling magnet reduces because a peeling acceleration opposing magnet exists on the conveyance pole in the rotation upstream of a peeling magnetic pole. It is a figure for demonstrating a quadrant.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing apparatus 2a Developing sleeve 2b Developing electrode 2d Peeling electrode 2e Pumping electrode 4 Doctor blade 5,6 Stirring screw roller 7 Peeling promotion magnet 12 Image forming unit 13 Charger 40 Photoconductor

Claims (10)

A developing device comprising a rotatable nonmagnetic sleeve and a magnetic field generating means having a plurality of magnetic poles fixedly arranged in the sleeve is arranged on the side of the latent image carrier, and the rotation center of the sleeve is set vertically. As the origin of the plane coordinate system, the two-component developer pumped up on the sleeve surface by rotating the sleeve counterclockwise is sent from below to above as a magnetic brush, and the development region from the fourth quadrant to the first quadrant of the developing roller cross section The latent image on the latent image carrier is visualized by sliding on the latent image carrier, and the developer peeling pole and the downstream magnetic pole to peel off the developer from the sleeve surface downstream of the sleeve rotation. In a developing device configured to have magnetic characteristics of the same polarity,
The developer peeling pole is located in the second quadrant in the cross section of the developing roller, and a magnet is arranged on the outer side in the radial direction of the sleeve facing the developer peeling pole, and the side facing the peeling pole is the same polarity as the peeling pole. A developing device. A developing device comprising a rotatable nonmagnetic sleeve and a magnetic field generating means having a plurality of magnetic poles fixedly arranged in the sleeve is arranged on the side of the latent image carrier, and the rotation center of the sleeve is set vertically. As the origin of the plane coordinate system, the two-component developer pumped up on the sleeve surface by rotating the sleeve counterclockwise is sent from below to above as a magnetic brush, and the development region from the fourth quadrant to the first quadrant of the developing roller cross section The latent image on the latent image carrier is visualized by sliding on the latent image carrier, and the developer peeling pole and the downstream magnetic pole to peel off the developer from the sleeve surface downstream of the sleeve rotation. In a developing device configured to have magnetic characteristics of the same polarity,
The developer peeling pole is located in the second quadrant in the cross section of the developing roller, a magnet is arranged on the outer side of the sleeve in the radial direction of the sleeve, and a position close to the sleeve is a non-magnetized surface. A developing device.   3. The developing device according to claim 2, wherein the magnetic pole arrangement of the magnet arranged outward in the sleeve radial direction has a magnetic pole of the same polarity as the developer peeling pole on the downstream side in the sleeve rotation direction. .   The developing device according to claim 1, wherein the magnetic flux density of the magnet arranged outward in the sleeve radial direction is at least the same as the magnetic flux density of the developer peeling pole.   The developing device according to claim 4, wherein the magnetic flux density of the magnet disposed outward in the sleeve radial direction is not more than five times the magnetic flux density of the developer peeling pole.   6. The magnet according to claim 1, wherein the magnet disposed radially outward of the sleeve is in an angular range between the developer peeling pole and the pole on the upstream and downstream sides of the sleeve rotation of the peeling pole. The developing device according to any one of the above.   6. The magnet according to claim 2, wherein the magnet disposed radially outward of the sleeve is in an angular range from the top of the developer peeling pole on the upstream side of the sleeve rotation to the developer peeling pole. The developing device described.   The developing device according to claim 1, wherein a magnet disposed outward in the sleeve radial direction is disposed on the developing casing wall.   A process cartridge comprising the developing device according to claim 1.   An image forming apparatus comprising the developing device according to claim 1.

Images