JP2009145463A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device capable of obtaining excellent cleaning performance by controlling the polarity of residual toner even when using an image carrier having low resistance, and an image forming apparatus. <P>SOLUTION: The intermediate transfer cleaning device 20 is equipped with a toner polarity control blade 21 controlling the electrification polarity of toner to be removed from an intermediate transfer belt 11 while coming into contact with the surface of the intermediate transfer belt 11, and a conductive brush 22 electrostatically removing the toner whose electrification polarity is controlled, and is provided with an insulating layer 26 on a surface of the toner polarity control blade 21 coming into contact with the intermediate transfer belt 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cleaning device that removes toner or the like from the surface of an image carrier and cleans the image carrier, and an image forming apparatus including the cleaning device.

  The above-described type of cleaning apparatus has been well known, and is particularly widely used in image forming apparatuses configured as electronic copying machines, printers, facsimiles, or multifunction peripherals thereof.

  Now, in color image forming apparatuses that have become mainstream in recent years, in addition to plain paper, which has been widely used as a transfer material, special designs used for thermal transfer such as special paper having a rough surface and iron prints as a design. Transfer paper is increasingly used.

  When such special paper is used, transfer defects may occur when transferring the toner image on the intermediate transfer member on which the color toners are superimposed to the special paper, compared to the case of conventional plain paper. Reduce. In view of this, an intermediate transfer member carrying a toner image, for example, an intermediate transfer belt, is given elasticity to improve the contact property with special paper during transfer.

  Further, there is a growing demand for higher image quality, and the toner tends to have a smaller particle size. Also, an image forming apparatus that employs a spheroidized toner instead of a pulverized toner instead of a pulverized toner has been commercialized in order to reduce toner manufacturing cost and improve transfer rate. Along with this, the blade cleaning method, which has been mainly used as a means for removing the toner remaining on the image carrier after image formation, removes the toner by bringing the rubber blade into contact with the image carrier. If the accuracy of the close contact with the surface of the carrier is low, the toner slips and the cleaning property tends to deteriorate. If the blade is pressed with a strong contact pressure in order to prevent it, the blade is turned over, causing a so-called streak-like or band-like cleaning failure, and it is difficult to keep stable cleaning performance. Even with spherical toner, cleaning can be performed by increasing the linear pressure extremely (specifically, linear pressure: 100 gf / cm or more). However, the life of the spherical toner is extremely shortened due to wear of the cleaning blade and scratches on the belt. The life of the cleaning blade at a normal linear pressure of 20 gf / cm (the life when a cleaning failure occurs due to shaving) is about 120 kp. When the linear pressure is 100 gf / cm, the life of the cleaning blade is extremely shortened to about 20 kp.

  Further, it is well known that the blade cleaning property is inferior to the cleaning property for the pulverized (atypical) toner with respect to the spherical toner whose transferability is good.

Due to the transition between the intermediate transfer belt and the toner, the intermediate transfer belt cleaning device cannot be handled by the conventional blade system, and various improvements have been made.
Japanese Patent No. 39002823

  The problems of Patent Document 1 include, for example, that in electrostatic cleaning, toner charged to the same polarity as the voltage applied to a cleaning member such as a cleaning roll or a cleaning brush cannot be removed, or when a large amount of toner comes instantaneously, When toner comes in multiple layers, it may not be able to clean sufficiently. And in order to solve these subjects, patent documents 1 exist.

  Incidentally, as described in paragraph [0006] of Patent Document 1, the toner to be cleaned (secondary transfer residual toner) has a uniform and sharp charge distribution (as shown in FIG. (It is an image in which the distribution of untransferred toner is close), but the distribution is from minus to plus across zero as shown in FIG. In particular, when the charge is near 0, the toner is not charged, and electrostatic cleaning is impossible.

Further, as described in paragraph [0008] of the same document, there is a situation where a large amount of toner or a multi-layer toner is cleaned.
Further, multi-layered toner comes at the time of process control described below (the charge distribution is the distribution of untransferred toner in FIG. 10C). In order for a color image forming apparatus to maintain high image quality and high reliability, it is essential that various characteristic values be detected and fed back to the image control system. To repeat the output of a certain number of images, toner replenishment control that controls the developer concentration at a constant level so that there is no change in color, or toner from the toner cartridge that contains the toner to the developer When toner transport control is performed so that toner clogging does not occur when transporting toner, if the toner concentration of the developer is detected by a magnetic sensor and the decrease in toner concentration falls below the threshold, toner replenishment or toner transport The control to do is well known. In addition to the magnetic sensor detection control, control is also performed in which a toner image is formed on the image carrier and the density is read by a photosensor. The control for reading the toner image with the photosensor is less configured to read the toner of each color on the intermediate transfer body after being transferred to the intermediate transfer body, rather than the configuration of reading each toner color on the developed photoreceptor. The number of parts is sufficient and the cost is low. Of course, these toner images (toner patterns) are not transferred to the transfer material, but are removed and collected by the intermediate transfer belt cleaning device.

  In addition, control for correcting color misregistration is also performed. At this time as well, a toner pattern is created on the intermediate transfer belt, read by a photo sensor, and the amount of deviation is detected to correct the writing position for forming a latent image on the photoconductor. Is removed and collected by the cleaning device without being transferred to the transfer material.

  As described above, untransferred toner may be input to the intermediate transfer body cleaning device in addition to the residual transfer toner remaining on the intermediate transfer body after being transferred to the transfer material, compared to the residual transfer toner. Since the amount is 5 to 10 times, the margin for brush cleaning is reduced, and cleaning may not be completed.

In Patent Document 1, since the toner collection member aligns the polarity of the toner with the regular charge and scrapes off a part of the toner, it seems as if the above problem has been solved.
However, the following problems arise.

  A high-resistance belt is used as the intermediate transfer belt of the image forming apparatus. However, a belt having a reduced volume resistivity ρv has been used in order to prevent afterimages and repeat fluctuations due to belt residual charges.

Also in Patent Document 1, in the example described in paragraph [0030], it is 10 ⁶ to 10 ¹⁴ Ω · cm, and a low resistance belt of 10 ⁶ Ω · cm can be used.
However, when a low-resistance belt is used, the polarity of the toner is hardly controlled even if a voltage is applied by bringing the toner polarity control blade into contact with the belt holding the toner. Since the toner held on the belt has a high resistance of 10 ¹⁰ to 10 ¹¹ [Ω], it is difficult to inject charges compared to the belt, and the voltage applied to the toner polarity control blade is low when the belt has a low volume resistivity. This is because it flows to the metal facing roller that is grounded.

  By the way, when the polarity is controlled by the polarity control member, it is necessary to control the transfer residual toner and the reverse transfer toner having various charge amount distributions to a single polarity. Therefore, a sufficient voltage must be applied to the polarity control member. Then, it has been found by the inventors that the toner charge amount after polarity control has a broader distribution as compared with toner polarity control with a corona charger. Further, in order to control all the transfer residual toner input to the polarity control member with a wide Q / d distribution as shown in FIGS. 10A and 10B to a single polarity, the transfer residual toner A (FIG. 10A The toner with a low charge amount such as)) becomes a high-charge toner with a negative polarity after polarity control, while the toner with a high charge amount with a positive polarity such as transfer residual toner B (FIG. 10B) After the polarity control, it becomes a negatively charged toner having a negative polarity.

  On the other hand, as is well known, low charge toner is cleaned with a weak cleaning electric field, and high charge toner is cleaned with a strong cleaning electric field. However, when the toner having a low charge amount is placed under a strong electric field, the opposite polarity charge is injected and reattached on the image carrier. In other words, the toner after polarity control has a single polarity, but has a broad charge amount distribution from a low charge amount to a high charge amount as described above, so the applied voltage to the cleaning brush shaft as a cleaning member is It is necessary to set the applied voltage so that the low charge amount toner is not reattached by the charge injection while the voltage is high enough to clean the high charge amount toner. In other words, the toner charge amount distribution must be such that cleaning can be performed when the voltage applied to the cleaning brush shaft is constant.

The method for measuring toner Q / M (: charge amount per unit weight of toner) and toner charge amount distribution is as follows. Moreover, the polarity control rate was defined below.
(Toner Q / M)

A toner patch pattern is formed on the photoconductor, and after completion of each process such as development, transfer, and polarity control, the main switch of the copier body is forcibly turned OFF, and the machine is stopped during the image formation. While the toner image formed on the photosensitive member or the transfer belt is sucked by an air pump using a suction jig, the coulomb amount of the toner is measured by a coulomb meter (Electrometer 617 manufactured by Kessley), and the suction jig is used. The toner charge amount (μC / g) per unit weight is calculated from the weight of the sucked toner and the coulomb amount.
(Toner charge distribution)

Measured with E-SPART analyzer manufactured by Hosokawa Micron. The toner adhering to the photoconductor is blown off with air and dropped onto the measuring section, and the particle size and the charge amount of each toner are measured. The “charge amount / toner particle size” is plotted on the x axis, and the “frequency ( %) = The number (pieces) / total number of samples (pieces) × 100 within the range of the preset “charge amount / toner particle size” histogram band, and graphed.
(Polarity control rate)

Calculation is based on the above-described measurement data of the toner charge amount distribution.
Polarity control rate [%] = number of polar toners to be controlled (pieces) / total number of samples (pieces) × 100

  The polarity to be controlled is the relative polarity of the voltage applied to the polarity control member when the surface potential of the photoconductor is used as a comparison target. For example, when the photoreceptor surface potential is −100 V and the polarity control member applied voltage is −700 V, “I want to control the toner to be negative”.

  In the electrostatic cleaning system using toner polarity control and single polarity application brush as in this system, it is important that the polarities of the toners input to the cleaning brush are aligned. In other words, it is important that the polarity control rate is high.

  SUMMARY OF THE INVENTION In view of the circumstances described above, an object of the present invention is to provide a cleaning device and an image forming apparatus that can control the polarity of residual toner and obtain good cleaning performance even when an image carrier having low resistance is used. To do.

  In order to solve the above problems, the present invention provides a conductive member for controlling the charging polarity of toner to be removed from the surface of the image carrier by contacting the surface of the image carrier and a toner having a controlled charging polarity. A cleaning device comprising a cleaning member for electrically cleaning is proposed, wherein an insulating layer is provided on a surface of the conductive member that comes into contact with the image carrier.

The present invention is effective when a counter member is provided on the back surface of the image carrier and at a position facing the conductive member, and a voltage is applied to the counter member.
Furthermore, the present invention is effective when a counter member is provided on the back surface of the image carrier and at a position facing the conductive member, a voltage is applied to the conductive member, and the counter member is grounded. Is.

Furthermore, the present invention is effective when the conductive member is a conductive blade.
Furthermore, the present invention provides the cleaning device according to any one of claims 1 to 4, wherein the cleaning member is rotated while the cleaning member is in contact with the surface of the image carrier. A conductive brush planted so as to extend radially outward from the outer periphery of the core metal, provided to contact and rotate with the brush bristles of the conductive brush, and has an electrical resistance layer on the outer peripheral surface, or A collecting roller having an insulating layer; a means for applying a voltage to the core of the conductive brush; a means for applying a voltage to the collecting roller; and scraping the toner collected by the collecting roller simultaneously with the collecting roller. It has an electroconductive recovery blade for imparting electric charge to the surface, and the electroconductive brush is effective when the brush resistance is 10 ⁶ to 10 ⁸ [Ω].

  Furthermore, the present invention is effective when the brush fibers constituting the conductive brush have a layer structure, and the conductive material imparting conductivity to the brush fibers has a fiber structure that is not exposed on the fiber surface. It is.

  Furthermore, the present invention is a method in which a solidified lubricant is brought into contact with the conductive brush, the lubricant is applied to the image carrier through the conductive brush, and scattered toner from the conductive brush is It is effective to have a blocking member that blocks adhesion on the image carrier.

  In order to solve the above problems, the present invention provides a photosensitive member as an image carrier, a toner image forming unit for forming a toner image on the photosensitive member, and a toner image formed on the photosensitive member. In the image forming apparatus having a primary transfer means for primary transfer to an intermediate transfer body as a carrier and a secondary transfer means for transferring a toner image carried on the intermediate transfer body to a recording material, the intermediate transfer body cleaning means An image forming apparatus using the cleaning device according to any one of claims 1 to 7 is proposed.

  According to the present invention, since the current does not flow excessively through the image carrier, the polarity of the toner can be reliably controlled. Moreover, since the structure is simple and cleaning is performed with the conductive member itself, the burden on the cleaning member can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing an internal configuration of a printer employing a so-called tandem indirect transfer system. Details of the engine are shown in FIG. As shown in FIG. 2, in this printer, four drum-shaped photoconductors 2a, 2b, 2c, and 2d that are rotatable in the clockwise direction are arranged in parallel at the approximate center of the apparatus main body 1. Around the photoreceptors 2a to 2d, a static elimination device (not shown) that neutralizes the surface, charging devices 3a to 3d that uniformly charge the surfaces of the photoreceptors 2a to 2d, and optical writing by laser light are performed. An exposure device 4 (not shown) for forming an electrostatic latent image on the charged portion and developing devices 5a to 5d for developing the electrostatic latent image are provided. Further, cleaning devices 7a to 7d for cleaning the surfaces of the photoconductors 2a to 2d after transfer are disposed around the photoconductor. This printer employs a so-called tandem system using four photoconductors, and the image forming component configuration provided around each of the photoconductors 2a to 2d is a color material handled by the developing devices 5a to 5d. (Toner) color is the same except that it is different (the components of the four sets of PCU will be described with reference to the photosensitive member 2, the charging device 3, the developing device 5, and the cleaning device 7). (The explanation is omitted.)

  An intermediate transfer unit 10 is provided above the photoreceptors 2a to 2d. As shown in FIG. 2, the intermediate transfer unit 10 is rotated counterclockwise in the drawing by the intermediate transfer belt 11 as a member to be cleaned being wound around the drive roller 12, the support rollers 13, 14, 15 and the tension roller 16. Driven. The intermediate transfer belt 11 has a multilayer structure, and the base layer is made of, for example, a fluororesin, PVD sheet, or polyimide resin with little elongation, and the surface is covered with a smooth coat layer such as a fluororesin.

  The resistance of the intermediate transfer belt is surface resistivity logΩ = 10.5 to 11.5, the volume resistivity is logΩ = 10 to 11, and the thickness is 100 μm. Further, transfer rollers 6a to 6d for transferring the toner images formed on the photoconductors 2a to 2d to the intermediate transfer belt 11 are disposed at positions facing the photoconductors 2a to 2d with the intermediate transfer belt 11 interposed therebetween. Is done. Further, an intermediate transfer belt cleaning device 20 for removing residual toner remaining on the intermediate transfer belt 11 after transfer by a secondary transfer device 8 described later is disposed on the left side of the tension roller 16. The tension roller 16 has a function of applying a constant tension to the intermediate transfer belt 11 and also serves as a counter roller that is a counter member of the intermediate transfer belt cleaning device 20. The intermediate transfer belt cleaning device 20 is configured to be detachable independently as will be described later because it has a shorter life than the intermediate transfer belt 11.

  A secondary transfer device 8 is disposed at a position facing the driving roller 12 with the intermediate transfer belt 11 in between. Although the secondary transfer device 8 of the present embodiment includes a secondary transfer roller, the secondary transfer device may be a belt that is stretched by several support rollers and a drive roller in addition to the rollers.

  The recording paper P (not shown) is stored in a paper feeding cassette 17 at the lower side in FIG. 1, and the uppermost recording paper P is conveyed to the registration roller pair 18 through a paper feeding path one by one by a paper feeding roller. . A fixing device 9 for fixing the transferred image on the recording paper P is disposed on the secondary transfer device 8. The secondary transfer device 8 described above also has a sheet transport function for transporting the recording paper P after image transfer to the fixing device 9.

  In the printer having the above configuration, when image formation is started by pressing a start switch (not shown) or the like, the intermediate transfer belt 11 is driven to rotate by a drive motor 12 (not shown) and the other rollers 13, 14, 15 are rotated. 16 are driven to rotate, and the intermediate transfer belt 11 rotates in the direction of the arrow. At the same time, in each image forming means, the photoreceptors 2a to 2d are rotated to form yellow, magenta, cyan, and black single-color images on the respective photoreceptors. Then, as the intermediate transfer belt 11 rotates, these single color images are sequentially transferred and superimposed on the intermediate transfer belt 11 to form a composite color image. On the other hand, the recording paper P is fed one by one from one of the paper feed cassettes 3 from the paper feed unit, and is abutted against the registration roller pair 18 and stopped. Then, the registration roller pair 18 starts rotating in synchronization with the composite color image on the intermediate transfer belt 11, and the recording paper P is fed between the intermediate transfer belt 11 and the secondary transfer device 8, and the secondary transfer device. The composite color image is transferred onto the recording paper P under the action of 8. The recording paper P after the image transfer is sent from the secondary transfer device 8 to the fixing device 9 and is fixed by the action of heat and pressure in the fixing device 9, and the recording paper P on which the transferred image is fixed is outside the machine. The paper is discharged.

  On the other hand, it is inevitable that some toner remains on the intermediate transfer belt 11 after image transfer, and this residual toner is removed from the intermediate transfer belt 11 by the intermediate transfer belt cleaning device 20 to prepare for the next image formation. .

FIG. 3 is a configuration diagram showing a schematic configuration of the intermediate transfer belt cleaning device 20 according to the present embodiment.
In FIG. 3, the intermediate transfer belt cleaning device 20 includes a polarity control blade 21 for controlling the polarity of the transfer residual toner on the intermediate transfer belt 11 in contact with the surface of the intermediate transfer belt at a position facing the tension roller 16. The conductive brush 22 for cleaning the polarity-controlled toner and the toner adhering to the conductive brush 22 on the downstream side in the rotation direction of the intermediate transfer belt 11 after the polarity control blade 21 A recovery roller 23 for recovering the toner from the brush, a conductive recovery blade 24 for contacting the surface of the recovery roller 23 to scrape the recovered toner and simultaneously applying a charge to the surface of the recovery roller 23, and an image forming apparatus main body. A coil member 25 is provided as a transport means for transporting to a waste toner tank (not shown).

  Further, the conductive brush 22 may be provided with a brush surface charge imparting member which is a conductive member (not shown) for imparting a charge to the surface thereof. This brush surface charge imparting member is a conductive member provided to compensate for the potential at the tip of the brush when a large amount of toner is collected on the brush. For example, a metal round bar or metal It is a plate-shaped member. Furthermore, the surface of the intermediate transfer belt 11 is constantly rubbed by the polarity control blade 21. Therefore, from the viewpoint of protecting the surface of the intermediate transfer belt, it is also effective to apply a lubricant to the surface with a brush. In this case, you may make it apply | coat by making the electroconductive brush 22 contact | abut the solidified lubricant (refer FIG. 17) mentioned later. Further, a lubricant applied with a brush may be provided with a coating blade for forming a thin film on the surface of the intermediate transfer belt, so that the lubricity can be improved.

  In addition, it is possible to apply the lubricant to the surface of the intermediate transfer belt using a brush for applying the lubricant separately from the conductive brush 22. With this configuration, since the toner is always collected in the cleaning conductive brush 22, the toner and the lubricant are mixed with each other, and the toner once collected at the time of applying the lubricant is attached to the intermediate transfer belt again. Although there is a possibility, such a problem can be prevented.

Next, the problem of the present invention will be described with reference to FIG. In the drawing, Ra is a toner polarity control blade resistance, and Rb is an intermediate transfer belt resistance.
Conventional image forming apparatuses use a high-resistance intermediate transfer belt. For example, a transfer belt having a surface resistivity of logΩ = 10.5 to 11.5, a volume resistivity of logΩ = 10 to 11 and a thickness of 100 μm was used. In this case, even if a voltage is applied to the toner polarity control blade 21, even if the grounded tension roller 16 (blade facing roller) is conductive such as metal or conductive plastic, the toner polarity control is applied with voltage. A large current did not flow from the blade to the tension roller side through the thickness direction of the intermediate transfer belt, and charge could be given to the residual toner on the intermediate transfer belt 11.

  Thus, the intermediate transfer belt resistance Rb (not the volume resistivity but the resistance value obtained from the current flowing from the toner polarity control blade to which the voltage is applied to the metal roller grounded via the intermediate transfer belt and the voltage applied to the toner polarity control blade. ) Is sufficiently large, a potential difference is generated between the surface potential of the intermediate transfer belt and the toner polarity control blade, and the toner on the intermediate transfer belt is charged with charge, so that the polarity can be controlled.

  On the other hand, when Rb is not sufficiently large, a current flows to the ground via the intermediate transfer belt 11 and the tension roller 16, so that the toner cannot be charged and the polarity cannot be controlled. An intermediate transfer belt whose Rb is not sufficiently large is a belt having a low volume resistivity, and is used to prevent abnormal images due to residual charges. The belt used in this embodiment had a volume resistivity R of logΩ = 7-8 when 250 V was applied.

  The intermediate transfer belt 11 is applied with -500 V using a toner polarity control blade having no insulation coating, the tension roller 16 is grounded, and a solid A3 size yellow image is output. The residual toner on the intermediate transfer belt 11 is toner. After passing through the polarity control blade 21, the switch of the image forming apparatus is turned off to forcibly stop the intermediate transfer belt 11, and the Q / d distribution before and after the portion where the toner polarity control blade 21 is in contact with the intermediate transfer belt 11 As a result, the polarity was not controlled, and conversely, the positive polarity toner increased. Even if the voltage applied to the toner polarity control blade 21 was variously changed to -300V, -700V, and + 500V, it could not be controlled to a single negative polarity. At this time, the current flowing through the tension roller 16 via the transfer belt was measured to be about 500 to 800 μA, and the aforementioned Rb was logΩ = 5 to 6. Further, when the current flows from 500 to 800 μA, since the current flows excessively, the toner polarity control blade 21 is deteriorated, so that it cannot be used under such conditions. Although the reason has not been elucidated, it is thought to be caused by alteration of the conductive material.

  A configuration and method for performing toner polarity control by the toner polarity control blade 21 even when the intermediate transfer belt 11 having such a low intermediate transfer belt resistance Rb is used will be described with reference to FIGS.

FIG. 5 is an enlarged view of the polarity control unit of FIG.
As shown in FIG. 5, an insulating layer 26 is provided on the surface of the toner polarity control blade 21 in contact with the intermediate transfer belt 11 to form a conductive and insulating two-layer blade. The conductive surface of the toner polarity control blade 21 is configured to be electrically connected to the metal blade holder 27, and a voltage having the same polarity as the normal charging polarity of the toner is applied to the blade holder 27. On the other hand, the conductive tension roller 16 such as metal or conductive plastic is grounded.

  The insulating layer 26 of the toner polarity control blade 21 includes an acrylic coat, a silicone coat (for example, a PC (polycarbonate) containing silicone particles), a ceramic coat, and a fluorine coat. What is necessary is just to select the thickness of a coating layer suitably. For example, in the case of a UV curable acrylic coat, the thickness is about 3 to 20 μm.

  In this case, even if the intermediate transfer belt resistance Rb is low, since the toner polarity control blade 21 has the insulating layer 26, the toner can be charged and the polarity can be controlled. The principle will be described. The circuit diagram is as shown in FIG.

  With this configuration, the voltage applied to the toner polarity control blade 21 works to charge the blade insulating layer 26 and the toner because the intermediate transfer belt resistance Rb is small. Therefore, even when the tension roller 16 is a conductive member such as metal and the intermediate transfer belt resistance Rb is small, the toner polarity can be controlled.

  FIG. 7 shows the toner Q / d distribution before and after contact with the toner polarity control blade 21 when a voltage of −2000 V is applied to the toner polarity control blade 21 and the tension roller 16 is grounded. As can be seen from FIG. 7, the plus / minus mixed toner before the input to the toner polarity control blade 21 is controlled to a minus single polarity. At this time, the current flowing through the toner polarity control blade 21 was 100 to 120 μA, and Rb was logΩ = about 7. (R = 2 × 10E7 [Ω])

  Further, since the resistance Rb of the intermediate transfer belt itself is low, the belt surface potential at the portion in contact with the toner polarity control blade 21 is increased, the efficiency of transferring the toner image on the photosensitive member 2 is lowered, and an abnormal image is generated. There is nothing. Further, the voltage applied to the toner polarity control blade 21 may be an AC + DC voltage or an AC voltage.

  Incidentally, in the above embodiment, a voltage of −2000 V is applied to the toner polarity control blade 21 and the tension roller 16 is grounded. However, as shown in FIG. 8, the toner polarity control blade 21 is grounded and the voltage is applied to the tension roller 16. May be configured to apply + 2000V. The circuit diagram is as shown in FIG.

Even in such a configuration, as shown in FIG. 7, the plus / minus mixed toner before the input to the toner polarity control blade 21 is controlled to a minus single polarity.
The toner polarity control will be described with reference to FIGS. 10 (a) and 10 (b).

  10 (a) and 10 (b) are graphs under certain conditions based on data obtained by measuring the charge amount Q of each toner and the particle diameter d of the toner using an E-spurt analyzer manufactured by Hosokawa Micron. 2 shows a Q / d (unit: fC / μm) distribution when sampling several hundred residual toners on the intermediate transfer belt when an image is formed by the illustrated image forming apparatus.

  FIG. 10A is a diagram in the case where the polarity of the transfer residual toner A in which plus and minus are 50% each is controlled by the toner polarity control blade 21, and FIG. 10B is a toner polarity control in which the transfer residual toner B is mostly positive. It is a figure at the time of carrying out polarity control by the blade 21.

FIG. 10C shows the Q / d distribution change in the case where the polarity of the mostly non-transferred toner is controlled by the toner polarity control blade 21.
The transfer residual toner on the intermediate transfer belt 11 is a toner having a distribution in which “+ polarity” and “−polarity” are mixed as shown in the transfer residual toner A in FIG. 10A and the transfer residual toner B in FIG. Thus, the toner is transferred to the position of the toner polarity control blade 21 by the rotation of the intermediate transfer belt 11. Although most toner is mechanically scraped off by the toner polarity control blade 21, so-called stick-slip is generated in the toner polarity control blade 21, and part of the toner slips through. The toner that has been mechanically scraped off falls naturally from the blade, is stored in the recovery unit, is transported by the recovery coil 25, and is recovered by the waste toner recovery unit.

  A voltage having the same polarity (-polarity) as the charging polarity of the toner is applied to the toner polarity control blade 21, and when the toner passes through the toner polarity control blade 21, the toner is charged to the normal charging polarity (-polarity). To do. For example, the applied voltage is -500V. FIG. 10A and FIG. 10B show the Q / d distribution of the controlled toner. Although the Q / d distribution after polarity control differs depending on the Q / d distribution of the transfer residual toner as the input toner (difference between A and B), both can be controlled to be substantially unipolar. Further, the non-transferred toner (toner at the time of process control) having a normal polarity and Q / d distribution in the case of FIG. 10C hardly changes or becomes slightly negative.

Next, the details when the charging polarity of the toner passing through the toner polarity control blade 21 to which a voltage (-polarity) having the same polarity as the toner is applied will be described.
The toner polarity control blade 21 has an electric resistance of 10E6 to 10E8 Ω · cm, a contact pressure with the intermediate transfer belt 11 of 20 to 40 g / cm, and a counter contact.

  The toner polarity control blade 21 is an elastic body made of, for example, polyurethane rubber, and imparts conductivity by kneading carbon black or an ionic conductive agent thereof. The electrical resistance was 1 × 10 6 Ω · cm. The electrical resistance is preferably about 2 × 10 5 Ω · cm to 5 × 10 7 Ω · cm. The blade conditions used this time are as shown in FIGS. The toner polarity control blade 21 has a plate shape bonded on a sheet metal, has a thickness of 2.4, 2.8 mm, a free length of 7, 9 mm, a JIS-A hardness meter of 60-80, and a rebound resilience of 45. %, But other values are possible. The thickness is preferably in the range of 1 to 3 mm. If the thickness is too thin, it will be difficult to ensure the amount of pressing against the intermediate transfer belt 11 due to the undulation of the surface of the intermediate transfer belt 11 and the toner polarity control blade 21 itself. The hardness may be in the range of 40 to 85 according to the JIS-A hardness meter (the toner polarity control blade 21 cannot clean 100%, and there is no problem even if the amount of slipping is slightly increased or decreased).

  When the toner is sandwiched between the toner polarity control blade 21 and the intermediate transfer belt, a current flows into the toner with the voltage applied to the toner polarity control blade 21, and the toner is charged with the polarity on the applied voltage side to become the toner polarity. Passes through the control blade 21. Also, the toner is discharged after passing through the blades shown in FIGS. 10 (a) and 10 (b) by discharging or injecting a minute gap between the entrance and exit of the wedge formed by the intermediate transfer belt 11 and the toner polarity control blade 21. The voltage is charged to the same polarity as the applied voltage as shown in FIG.

Next, the cleaning operation after toner polarity control will be described.
In FIG. 3, the toner charged to the regular charging polarity by the toner polarity control blade 21 is transferred to the position of the next conductive brush 22 by the rotation of the intermediate transfer belt 11. The conductive brush 22 is made of conductive polyester, and a collection roller 23 is provided so as to be in contact with the conductive brush 22. The conductive brush 22, the collection roller 23, and the toner discharge coil 25 are rotated by driving means. A voltage (+ polarity) opposite in polarity to the charging polarity of the toner is applied to the core of the conductive brush 22 by a power source, and the toner that has passed through the polarity control blade 21 is electrostatically adsorbed. The toner that has moved onto the conductive brush 22 moves with a potential gradient to the collecting roller 23 that has applied a voltage of + polarity higher than that of the conductive brush 22 to the shaft by the power source. The toner on the collection roller 23 is scraped off by the conductive collection blade 24 and is discharged out of the apparatus by the toner discharge screw 524 or returned to the developing unit. In order to maintain the surface potential of the collection roller 23, the conductive collection blade 24 is applied with a + polarity voltage equal to or higher than the voltage applied to the collection roller 23 core metal.

Specific configuration conditions of the conductive brush 22 and the collection roller 23 are as follows.
The conductive brush 22 is made of a brush material: conductive polyester (containing conductive carbon inside the fiber and the fiber surface is polyester; so-called core-sheath structure)

Brush resistance: 10E7Ω (applied voltage 100-600V)
Brush shaft applied voltage [V]: 1000V
Brush flocking density: 100,000 / inch ² , fiber diameter of about 25 to 35 μm, with brush tipping treatment, brush diameter φ16 mm

Brush fiber biting amount to the intermediate transfer belt 11: 1 mm
The brush fiber is conductive as a whole, but the fiber surface is covered with an insulating layer. By having an insulating layer on the fiber surface, it becomes difficult for current to flow when the brush and the intermediate transfer belt come into contact with each other, and it becomes difficult for excess current to flow when the brush fiber electrostatically attracts toner from the intermediate transfer belt. Therefore, the toner once captured by the brush is less likely to adhere to the intermediate transfer belt. However, even if such a brush is used, if a voltage that breaks the insulation of the fiber surface and allows current to flow is applied to the brush shaft, the toner is returned to the intermediate transfer belt 11 as a result. Therefore, care must be taken when setting the voltage value.

  Furthermore, if a slanting treatment is performed in which the hair is tilted in one direction after being formed into a brush roll shape, the conductive agent exposed on the fiber cross section becomes difficult to come into contact with the intermediate transfer belt 11, so that charge injection into the toner is further achieved. And the margin for cleaning is improved.

  FIG. 11 shows the cleaning properties when the brush resistance R is logΩ = 5, 7, and 9. Since the applied voltage is large when logΩ = 9, the power supply cost increases. When LogΩ = 5, current easily flows through the intermediate transfer belt 11, so that the toner is charged to a positive polarity at a lower voltage than when logΩ = 7, and reattaches to the intermediate transfer belt 11, so that there is a margin for cleaning. small. Therefore, the condition of logΩ = 7 is most suitable.

The collection roller condition is
Collection roller core metal material: SUS,
Recovering roller surface material: PVDF (thickness 100 μm) surface layer on acrylic UV cured resin layer (thickness 3-5 μm)

Amount of brush fiber biting into the collection roller: 1 mm
Recovery roller mandrel applied voltage: + 1400V
The collection blade condition is

Conductive carbon-containing polyurethane rubber volume resistance: 10E6 Ω · cm (measured at 25 ° C, 50%)
Blade contact angle: 20 °, blade thickness: 2.8 mm, blade biting amount into collection roller: 0.6 mm

Applied voltage to recovery blade: 2400V
However, the brush resistance is a value obtained by measuring the current by applying a voltage to the brush core bar by applying a 1 mm conductive brush to a SUS roller having a diameter of 10 mm and bringing them into contact with each other and rotating them at 200 mm / sec. .

  As the collection roller 23, a SUS core metal (φ16) having a PVDF thickness of 100 μm and an acrylic UV curable resin layer on the surface (hereinafter referred to as a high resistance roller) was used. The roller resistance is calculated by applying a voltage of 1000 V under a 10 ° C. 15% environment and a 32 ° C. 80% environment, and measuring the current, and log Ω = 12-13. Not only the roller used in the present embodiment, but also the same performance can be obtained by covering a conductive core metal with a high resistance elastic tube of several μm to 100 μm, or further insulating coating to make the roller resistance log Ω = 12-13. Can be obtained. Further, a blade 24 for cleaning the collection roller is formed of conductive polyurethane rubber, and voltages having the same polarity are applied to the conductive brush 22, the collection roller 23, and the conductive collection blade 24, respectively.

Next, the conductive recovery blade 24 will be described.
A voltage is applied to the core of the collecting roller 23 and its surface potential is measured to be the same as the applied voltage. However, when a large amount of toner is input during the cleaning operation, the surface potential of the collecting roller is Decreases with toner input.

  When the surface potential of the collection roller 23 decreases, a potential difference from the brush tip potential (hereinafter referred to as a collection potential difference) cannot be ensured, and the ability to collect toner from the conductive brush 22 decreases. For this reason, the recovery potential difference can be secured if the image forming operation is for one A4 size sheet, but the recovery potential difference cannot be secured if the continuous printing operation is performed and the amount of toner input to the conductive brush 22 is large. There is a problem that toner is accumulated in the conductive brush 22 and the toner is discharged from the conductive brush 22 onto the intermediate transfer belt 11. For this reason, a voltage is applied by using the collection blade as a conductive collection blade, and a charge is applied to the surface of the collection roller 23 to maintain a collection potential difference and maintain the collection performance.

  The application of voltage to the polarity control blade 21 for maintaining such a recovery potential difference is not very necessary when the polarity control blade 21 is new, because there is little toner slipping through the polarity control blade 21. However, the polarity control blade may be used for a long time to increase the amount of slip-through toner, or in a low-temperature and low-humidity environment, the slip-through toner from the polarity control blade 21 increases more than in a high-temperature and high-humidity environment. It is valid.

  By the way, in the image forming apparatus, in order to maintain the image density constantly so that the color tone is reproduced with high image quality and repeat of the same image, control for adjusting the image forming process condition as necessary is conventionally performed. Has been done.

  For example, the developer must be triboelectrically charged by mixing the toner and carrier and the toner charge amount must be constant, but the toner charge amount is attenuated after several hours from the previous image forming operation. If an image is formed immediately without performing the operation, there is a problem that the amount of development on the image carrier becomes large with a low toner charge amount. In addition, since the toner density in the developing device decreases when continuous image formation is performed, it is necessary to supply toner to the developing device. However, in order to supply toner without excess or deficiency, a developer (toner and carrier There is a method of replenishing toner by detecting the toner concentration in the toner) with a sensor for detecting the magnetic permeability of the developer. In addition, in order to improve the detection accuracy, a toner pattern having a size of several centimeters × several centimeters for each color is created on the transfer belt while changing the charging bias and developing bias, and then the image density is measured by a photo sensor. The relationship between the read image density and the development potential (the difference between the development bias and the photoreceptor surface potential) is obtained, and the image is always set to the target density according to the image density and development potential data table stored in the control unit. Control for determining and correcting the charging bias and the developing bias is also performed. In the present embodiment, ten toner patterns having an area of 2 cm × 2 cm having different image densities are formed on each color intermediate transfer belt and read by a photo sensor.

At this time, the toner adhesion amount is about 0.1 [mg / cm ² ] at the minimum and 0.55 [mg / cm ² ] at the maximum. ing. (See Fig. 10 (c))

In addition, color misregistration adjustment may be performed in order to superimpose toner images of respective colors without misalignment.
A color misregistration correction pattern similar to the above-described toner pattern is created on the intermediate transfer belt, and is read by a sensor to measure the image position and control to correct the writing position is also performed. Also at this time, a solid pattern with a high image density is created on the intermediate transfer belt so that the sensor does not detect it erroneously.

At this time, the toner adhesion amount is such that a toner pattern having a constant image density and a constant size is Y, M, C, K, Y, M, C, K in the order of colors determined in the running direction of the intermediate transfer belt. Create an image, read it with a photo sensor placed in contact with the intermediate transfer belt in a non-contact manner, read the position of each color pattern, calculate the amount of deviation, and shift the photoconductor writing timing by the amount of deviation from the correct position. This is corrected. At this time, the toner adhesion amount is about 0.3 [mg / cm ² ].

  As described above, solid images that are not transferred to paper are created on the intermediate transfer belt 11 at various timings, and the toner patterns must be collected by the intermediate transfer belt cleaning device. However, in the conventional blade cleaning device, if the blade tip deteriorates due to long-term use, it may be difficult to remove the solid untransferred toner on the intermediate transfer belt 11 at a time. In such a case, the toner on the intermediate transfer belt 11 that could not be cleaned is transferred onto the transfer paper during the next printing operation, resulting in an abnormal image.

  Therefore, in the case where there is toner that is not transferred onto a transfer material such as paper and is input to the intermediate transfer belt cleaning device 20 as described above, the polarity control blade 21 and the electrostatic cleaning device are combined. As a result, the toner input to the conductive brush 22 can be reduced, and the non-transferred toner has the same polarity as the normal charging polarity. Therefore, the toner can be satisfactorily cleaned by applying a voltage having a polarity opposite to the normal charging polarity of the toner to the conductive brush 22, the recovery roller 23, and the conductive recovery blade 24.

  Further, even if the polarity control blade 21 deteriorates due to long-term use and the amount of toner that passes through the polarity control blade 21 increases, the polarity of the input toner of the conductive brush 22 remains the normal polarity. The conductive brush 22 can be sufficiently cleaned. Further, since a voltage is applied to the conductive recovery blade 24, even if a large amount of toner is input to the conductive brush 22, the function of maintaining the recovery roller surface potential works and the recovery performance does not deteriorate. As a result, the surface of the intermediate transfer belt 11 can be maintained normally, which contributes to a longer life. Here, there is not much problem in using the conductive brush 22 for a long period of time, and the brush fibers used in the present embodiment are less likely to fall down even when used for a long period of time. The amount of biting into the belt 11 was reduced, and there was no case of poor cleaning.

Next, another embodiment of the present invention is shown in FIG.
The embodiment shown in FIG. 15 is basically the same as the embodiment shown in FIG. 3 except that the tension roller 16 is floated. Therefore, in FIG. 14, the same members as those shown in FIG. However, the applied bias needs to be adjusted to an appropriate value.

  By making the tension roller 16 float, even if the polarity control blade 21 deteriorates and the insulating layer becomes thin, overcurrent flows and polarity control becomes impossible.

Yet another embodiment of the present invention is shown in FIG.
In the embodiment shown in FIG. 15, conductive rollers 30 and 31 as conductive members grounded on the upstream side and the downstream side in the moving direction of the tension roller 16 are brought into contact with the intermediate transfer belt 11 in FIG. Other than the embodiment, the other configurations are basically the same. Therefore, in FIG. 15, the same members as those shown in FIG. However, the applied bias needs to be adjusted to an appropriate value.

  The conductive rollers 30 and 31 are configured by a metal roller pressed against the back surface of the intermediate transfer belt 11. In the embodiment of FIG. 3 in which the conductive rollers 30 and 31 are not provided, when the polarity control blade 21 deteriorates and an overcurrent flows upstream or downstream of the intermediate transfer belt 11, the transfer roller 6 or the secondary roller Since the current flows into the transfer device 8, the quality of the primary transfer or the secondary transfer is deteriorated. However, if the conductive rollers 30 and 31 are present, even if an overcurrent flows, the current flows to the conductive rollers 30 and 31, so that the quality of the primary transfer or the secondary transfer does not deteriorate.

Yet another embodiment of the present invention is shown in FIG.
The embodiment shown in FIG. 16 differs from the embodiment of FIG. 3 only in that the position of the conductive brush 22 that contacts the intermediate transfer belt 11 is not opposed to the tension roller 16 and is offset from the roller 16. Other configurations are basically the same. Therefore, in FIG. 16, the same members as shown in FIG. However, the applied bias needs to be adjusted to an appropriate value.

  If comprised in this way, overcurrent will generate | occur | produce according to the case where the polarity control blade 21 deteriorates or use conditions. This overcurrent flows to the grounded tension roller 16, but if the conductive brush 22 faces the tension roller 16 as shown in FIG. 3, the overcurrent may flow back to the conductive brush 22 and the cleaning performance may deteriorate. is there. However, with the configuration shown in FIG. 16, since no current flows through the conductive brush 22 even when an overcurrent occurs, the toner from the intermediate transfer belt 11 can be removed satisfactorily.

Next, another embodiment of the intermediate transfer belt cleaning device 20 according to the present invention will be described with reference to FIG.
The embodiment shown in FIG. 17 is different from the embodiment of FIG. 3 in that the lubricant 32 is brought into contact with the conductive brush 22 and the lubricant 32 is applied to the intermediate transfer belt 11 via the conductive brush 22. Other configurations are basically the same. Therefore, in FIG. 17, the same members as those shown in FIG.

  Since the surface of the intermediate transfer belt 11 is constantly rubbed by the polarity control blade 21, the lubricant 32 is applied to protect the surface of the intermediate transfer belt 11 and reduce the wear amount of the polarity control blade 21. In this case, the solidified lubricant 32 is disposed at a position where it comes into contact with the conductive brush 22 after coming into contact with the collection roller 23, and the lubricant is applied via the conductive brush 22. The solid lubricant 32 is held so as to come into contact with the conductive brush 22 via a spring 33 placed on a support member 34 fixed to the casing of the intermediate transfer belt cleaning device 20. Even if it is smaller, the conductive brush 22 is appropriately brought into contact with the pressure of the spring 33.

  As specific lubricants, fatty acid metal salts are suitable, especially zinc stearate, calcium stearate, iron stearate, copper stearate, magnesium palmitate, calcium palmitate, manganese oleate, lead oleate, etc. ing.

  By the way, in order to prevent the toner floating on the entire intermediate transfer belt cleaning device 20 from coming out of the cleaning unit, the gap between the intermediate transfer belt 11 and the intermediate transfer belt 11 is shielded by using the outlet seal 35 of FIG. It has been found that the toner adhering to the brush strikes the solid lubricant as the brush 22 rotates and adheres to the intermediate transfer belt 11 in the region A in FIG.

Accordingly, the outlet seal 35 is improved to provide a shielding member 36 shown in FIG.
The shielding member 36 is disposed such that a urethane rubber sheet having a thickness of 200 μm is attached to the casing of the cleaning device and the amount of biting into the conductive brush 22 is 1 mm. The pasting allowance with the casing is 3 mm, and the protruding amount is 7 mm.

  The material of the shielding member is not limited to urethane rubber, and any material having insulation and flexibility may be used. Further, the thickness is not limited to 200 μm as long as the thickness is not involved by the brush rotation and is not splashed by the air flow by the brush rotation.

  The toner polarity control of the intermediate transfer belt cleaning device 20 of FIGS. 17 and 18 is the same as that of the intermediate transfer belt cleaning device 20 of FIG. 3, but the voltage applied to the toner polarity control blade 21 is, for example, −− Set to 2000V.

  FIG. 19A is a diagram in which the polarity of the transfer residual toner A in which plus and minus are 50% each is controlled by the toner polarity control blade 21, and FIG. 19B is a toner polarity control in which the transfer residual toner B is mostly positive. FIG. 19C is a Q / d distribution change diagram when the polarity is controlled by the toner polarity control blade 21 when the polarity is controlled by the blade 21 and FIG.

  The transfer residual toner on the intermediate transfer belt 11 is a toner having a distribution in which “+ polarity” and “−polarity” are mixed as shown in the transfer residual toner A in FIG. 19A and the transfer residual toner B in FIG. Thus, the toner is transferred to the position of the toner polarity control blade 21 by the rotation of the intermediate transfer belt 11. Although most toner is mechanically scraped off by the toner polarity control blade 21, so-called stick-slip is generated in the toner polarity control blade 21, and part of the toner slips through. The toner that has been mechanically scraped off falls naturally from the blade, is stored in the recovery unit, is transported by the recovery coil 25, and is recovered by the waste toner recovery unit.

  A voltage having the same polarity (-polarity) as the charging polarity of the toner is applied to the toner polarity control blade 21, and when the toner passes through the toner polarity control blade 21, the toner is charged to the normal charging polarity (-polarity). To do. For example, the applied voltage is -2000V. FIG. 19A and FIG. 19B show the Q / d distribution of the controlled toner. Although the Q / d distribution after polarity control differs depending on the Q / d distribution of the transfer residual toner as the input toner (difference between A and B), both can be controlled to be substantially unipolar.

  FIG. 20 is a diagram showing a detailed configuration of an embodiment of a unit around the photoconductor 2, which is one of the image forming portions for four colors shown in FIG. The photoreceptor cleaning device 7d will be described. Since the remaining photoconductor cleaning devices 7a to 7c are the same in the following, description will be made with the subscript d omitted.

  The photoconductor cleaning device 7 is provided with a polarity control blade 71 for controlling the polarity of the residual toner on the photoconductor 2 in contact with the surface of the photoconductor. The conductive brush 72 for cleaning the controlled toner, the collection roller 73 for collecting the toner adhering to the conductive brush 72 from the brush, and collecting the toner collected by contacting the surface of the collection roller 73 at the same time. A conductive recovery blade 74 that imparts an electric charge to the surface of the roller, and a coil member 75 for conveyance to a waste toner tank (not shown) provided in the image forming apparatus main body are provided. In order to protect the surface of the photoreceptor in the charging process, the lubricant is applied by a brush, so that the solidified lubricant is brought into contact with the conductive brush 72 and the lubricant 76 is applied. .

  The lubricant 76 is solidified and held so as to contact the conductive brush 72 via a spring 77 placed on a support member 78 fixed to the casing, and the solid lubricant 76 becomes smaller with time. Even so, the pressure of the spring 77 is appropriately in contact with the conductive brush 72. A lubricant is applied to the photosensitive member 2 in contact with the conductive brush 72.

  The shielding member 79 is disposed such that a urethane rubber sheet having a thickness of 200 μm is attached to the casing of the cleaning device 7 so that the amount of biting into the conductive brush 72 is 1 mm. The pasting allowance with the casing is 3 mm, and the protruding amount is 7 mm.

  The material of the shielding member 79 is not limited to urethane rubber, and any material having insulation and flexibility may be used. Further, the thickness is not limited to 200 μm as long as the thickness is not involved by the brush rotation and is not splashed by the air flow by the brush rotation.

A color printer of another embodiment of the image forming apparatus according to the present invention is shown in FIG.
In FIG. 21, a photosensitive drum 101 as an image carrier, a writing optical unit, a developing device black 102a, cyan 102b, magenta 102c, yellow 102d, an intermediate transfer device 110, a paper transfer device 103, a fixing device (not shown), and the like. ing.

  The photosensitive drum 101 rotates counterclockwise as indicated by an arrow. Around the photosensitive drum 101, a photosensitive member cleaning device 104, a charge eliminating lamp 105, a charger 106, and developing devices 102a to 102d are arranged. The color image data from the scanner is converted into an optical signal, optical writing corresponding to the image of the original is performed, and an electrostatic latent image is formed on the photosensitive drum 101.

  The developing devices 102a to 102d include a developing sleeve that rotates by bringing the ears of the developer into contact with the surface of the photosensitive drum 101 in order to develop the electrostatic latent image, and a developer that rotates to pump up and stir the developer. It consists of paddles. The toner in each developing device is negatively charged in this example by stirring with the ferrite carrier, and each developing sleeve is charged with a negative DC voltage Vdc by a developing bias power source as a developing bias applying means (not shown). Is applied, or a developing bias of only a DC voltage is applied, and the developing sleeve is biased to a predetermined potential with respect to the metal substrate layer of the photosensitive drum 101.

A toner image of each color is sequentially formed on the photosensitive drum 101, and the formation order can be selected as appropriate.
The intermediate transfer device 110 includes an intermediate transfer belt 111, a belt cleaning device 113, and the like. The intermediate transfer belt 111 is stretched around a driving roller 112, a bias roller 115, a cleaning counter roller 116, a driven roller 114, and other driven rollers, and is driven and controlled by a driving motor (not shown).

By applying a voltage to the bias roller 115, the toner image on the photosensitive drum 101 is primarily transferred onto the intermediate transfer belt 111.
Primary transfer bias voltage is 1st color: 1200V, 2nd color: 1300V, 3rd color: 1400V, 4th color 1500V,

Secondary transfer bias voltage is 1300V
Photoreceptor potential: Image part: -80 to -130V, Background part: -500 to -700V
Toner density: 2 to 6 wt% toner charge for each color (inside developer): each color −10 to −25 μC / g transfer roller: hydrin rubber roller covered with PFE tube, volume resistivity: 109 Ω · cm intermediate transfer belt: The electric resistance of the carbon-dispersed fluororesin ETFE (ethylene tetrafluoroethylene) intermediate transfer belt is 1010 Ω · cm in volume resistivity and 109 Ω in surface resistivity. The belt cleaning device 113 of the intermediate transfer device 110 is shown in FIG. 3 or FIG. The intermediate transfer belt cleaning device 20 shown in FIG.

Further, an AC voltage + DC voltage or a DC voltage is applied to the paper transfer roller 103 to collectively transfer the superimposed toner images on the intermediate transfer belt 111 onto the recording paper.
In the color copying machine configured as described above, when an image forming cycle is started, first, the photosensitive drum 101 is rotated counterclockwise as indicated by an arrow, and the intermediate transfer belt 111 is rotated clockwise as indicated by an arrow by a drive motor (not shown). As the intermediate transfer belt 111 rotates, Bk toner image formation, C toner image formation, M toner image formation, and Y toner image formation are performed, and finally the Bk, C, M, and Y are overlaid on the intermediate transfer belt in this order. Thus, a toner image is formed.

  The Bk toner image is formed as follows. The charger 106 uniformly charges the photosensitive drum 101 to about −700 V with negative charge by proximity roller charging. A semiconductor laser 107 indicated by an arrow performs raster exposure based on the Bk color image signal. When this raster image is exposed, in the exposed portion of the photosensitive drum 101 that is initially uniformly charged, the charge proportional to the amount of exposure light disappears, and a Bk electrostatic latent image is formed. When the negatively charged Bk toner on the Bk developing sleeve comes into contact with this Bk electrostatic latent image, the toner does not adhere to the remaining part of the photosensitive drum 101, that is, the part without charge, that is, Bk toner is attracted to the exposed portion, and a Bk toner image similar to the electrostatic latent image is formed. The Bk toner image formed on the photosensitive drum 101 is transferred to the surface of the intermediate transfer belt 111 that is driven at a constant speed in contact with the photosensitive drum 101 by the intermediate transfer device 110 as follows. (Hereinafter, toner image transfer from the photosensitive drum 101 to the intermediate transfer belt 111 is referred to as belt transfer).

  A bias voltage having a polarity opposite to that of the toner on the photoconductor 101, in this example, a positive polarity is applied to the bias roller 115 by a power source (not shown), and the intermediate transfer belt portion wound around the bias roller 115 is a surface of the photoconductor 101. In this state, the intermediate transfer belt 111 rotates in the direction indicated by the arrow in FIG. 21 by the rotation of the driving roller 112 driven by a motor (not shown). The photosensitive member 101 and the intermediate transfer belt 111 are controlled to move in the same direction at the contact portion between them and to move at a constant speed. Since a voltage having a polarity opposite to that of the toner is applied to the bias roller 115, when the Bk toner image on the photoconductor reaches the primary transfer region which is a contact portion between the photoconductor 101 and the intermediate transfer belt 111, Bk The toner image is electrostatically drawn onto the surface of the intermediate transfer belt 111 and is primarily transferred onto the surface of the intermediate transfer belt 111.

  Some untransferred residual toner on the photoconductor drum 101 is cleaned by the photoconductor cleaning device 104 in preparation for reuse of the photoconductor drum 101. The collected toner is stored in a waste toner tank (not shown) via a collection pipe.

  When the cleaning device 7 shown in FIG. 20 of the present invention is used for the photoconductor cleaning device 104, good cleaning properties can be obtained. The surface of the photosensitive drum 101 after the belt transfer is cleaned by the photosensitive member cleaning device 104 and then uniformly discharged by the static eliminating lamp 105.

  On the intermediate transfer belt 111, Bk, C, M, and Y toner images sequentially formed on the photosensitive drum 101 are sequentially aligned on the same surface to form a four-color superimposed toner image, and the next transfer In the process, the four color toner images are collectively transferred to the recording paper by the paper transfer roller 103. When the intermediate transfer belt cleaning device 20 shown in FIGS. 3 and 18 is used as the intermediate transfer belt cleaning device of this embodiment, good cleaning properties can be obtained.

Next, the toner suitably used for the color printer of the present invention will be described.
In order to reproduce minute dots of 600 dpi or more, the toner preferably has a volume average particle diameter of 3 to 6 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. FIG. 22 is a diagram schematically illustrating the shape of the toner in order to explain the shape factor SF-1. 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.

SF-1 = {(MXLNG) ² / AREA} × (100π) / 4 Formula (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. FIG. 23 is a diagram schematically illustrating the shape of the toner in order to explain the shape factor SF-2. The shape factor SF-2 indicates the ratio of unevenness in the shape of the toner, 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 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 photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force 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.

In addition, a toner suitably used for a color printer is a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent are dispersed in an organic solvent. Is 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-isocyanatomethylcaproate, 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; phenol derivatives, oximes, caprolactam And a combination 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 less 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 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 , Phenol-condensate E-89 (above, manufactured by Orient Chemical Co., Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, manufactured by Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSYVP2038, copy blue PR of triphenylmethane derivative, copy charge NEG VP2036 of quaternary ammonium salt, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (manufactured by Nippon Carlit) ), 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, 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 to 2 μm, and particularly preferably 5 × 10 −3 to 0.5 μm. 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 size of 5 × 10 −4 μm or less, the electrostatic force and van der Waals force with the toner are markedly improved. Even when stirring and mixing inside the developing device is performed, a fluidity-imparting agent is not detached from the toner, a good image quality that does not cause fireflies and the like is obtained, and a reduction in residual toner is further achieved. . 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 salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, fatty acid amide derivatives, polyhydric alcohols 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).

  In addition, examples of the cationic surfactant include aliphatic quaternary ammonium salts such as aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, and perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts. , 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) Manufactured), MegaFuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footgent 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 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.

  The toner has a substantially spherical shape and can be represented by the following shape rule. 24A, 24B, and 24C are diagrams schematically showing the shape of the toner. 24A, 24B, and 24C, when substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), The toner of the invention has a ratio (r2 / r1) between the major axis and the minor axis (see FIG. 24B) of 0.5 to 1.0, and a ratio between the thickness and the minor axis (r3 / r2) (FIG. 24 (c)) 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.

1 is a schematic diagram illustrating a configuration of an intermediate transfer type image forming apparatus according to the present invention. FIG. 2 is an enlarged view showing a main part of the image forming apparatus in FIG. 1. It is an explanatory view showing a detailed configuration of an intermediate transfer cleaning device. It is a circuit diagram explaining the subject of this invention. It is an enlarged view showing a main part of the intermediate transfer cleaning device according to the present invention. FIG. 4 is a circuit diagram illustrating the principle of the intermediate transfer cleaning device of FIG. 3. FIG. 6 is a diagram illustrating a toner Q / d distribution before and after contact with a toner polarity control blade. It is a figure which shows the intermediate transfer cleaning apparatus in other embodiment which concerns on this invention. FIG. 9 is a circuit diagram illustrating the principle of the intermediate transfer cleaning device of FIG. 8. (A), (b), and (c) are diagrams showing charge distributions before and after toner polarity control of residual toner in different states. It is a graph which shows the cleaning property when the resistance of the conductive brush is logΩ = 5, 7, 9. It is a figure which shows the difference by the environment of the resistance value in two different toner polarity control blades, and volume low efficiency. It is a figure which shows the conditions of the toner polarity control blade of FIG. It is a schematic block diagram of the intermediate transfer cleaning apparatus which shows other embodiment of this invention. It is a schematic block diagram of the intermediate transfer cleaning apparatus which shows other embodiment of this invention. It is a schematic block diagram of the intermediate transfer cleaning apparatus which shows further another embodiment of this invention. It is a schematic block diagram of the intermediate transfer cleaning apparatus which shows another embodiment of this invention. FIG. 18 is a schematic view showing an improved embodiment of the intermediate transfer cleaning device shown in FIG. 17. (A), (b), and (c) are diagrams showing charge distributions before and after toner polarity control of the remaining toner in different states when -2000 V is applied to the toner polarity control blade. It is a figure which shows one image formation part among the four shown in FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a plurality of developing units on one photoconductor. It is explanatory drawing of shape factor SF-1. It is explanatory drawing of shape factor SF-2. (A), (b), (c) is a figure which shows the shape of a toner typically.

Explanation of symbols

2 Photoconductor 7 Cleaning device 10 Intermediate transfer device 11 Intermediate transfer belt 16 Tension roller 20 Intermediate transfer cleaning device 21 Polarity control blade 22 Conductive brush 23 Collection roller 23
24 Conductive recovery blade 26 Insulating layer

Claims (8)

A conductive member that contacts the surface of the image carrier and controls the charging polarity of the toner to be removed from the image carrier;
In a cleaning device comprising a cleaning member that electrostatically cleans toner whose charge polarity is controlled,
A cleaning apparatus, wherein an insulating layer is provided on a surface of the conductive member that contacts the image carrier.   The cleaning apparatus according to claim 1, wherein a counter member is provided on a back surface of the image carrier and at a position facing the conductive member, and a voltage is applied to the counter member.   2. The facing member according to claim 1, wherein a facing member is provided on a back surface of the image carrier and at a position facing the conductive member, a voltage is applied to the conductive member, and the facing member is grounded. The cleaning device described.   The cleaning device according to claim 1, wherein the conductive member is a conductive blade. 5. The cleaning device according to claim 1, wherein the cleaning member rotates the conductive fiber in contact with the surface of the image bearing member in a diameter direction from the outer periphery of the conductive cored bar. A conductive brush planted so as to extend outward, provided so as to contact and rotate with the brush bristles of the conductive brush, and has an electrical resistance layer on the outer peripheral surface or a collection roller having an insulating layer; A means for applying a voltage to the core of the conductive brush; a means for applying a voltage to the collecting roller; and a conductive means for scraping off the toner collected by the collecting roller and simultaneously applying a charge to the surface of the collecting roller. A cleaning device, wherein the conductive brush has a brush resistance of 10 ⁶ to 10 ⁸ [Ω].   6. The cleaning according to claim 5, wherein the brush fibers constituting the conductive brush have a layer structure, and the conductive material imparting conductivity to the brush fibers has a fiber structure that is not exposed on the fiber surface. apparatus.   7. The cleaning device according to claim 5 or 6, wherein a solidified lubricant is brought into contact with the conductive brush, the lubricant is applied to the image carrier through the conductive brush, and the conductive brush is used. A cleaning apparatus comprising: a blocking member that blocks toner scattered from the toner from adhering to the image carrier. A photoreceptor as an image carrier;
Toner image forming means for forming a toner image on the photoreceptor;
Primary transfer means for primary transfer of a toner image formed on the photosensitive member to an intermediate transfer member as an image carrier;
In an image forming apparatus having secondary transfer means for transferring a toner image carried on the intermediate transfer member to a recording material,
An image forming apparatus using the cleaning device according to claim 1 as a cleaning unit for the intermediate transfer member.

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