JP2007171742A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus equipped with a mechanism which removes an external additive agent and residue toner left on an intermediate transfer surface while suppressing a load on the intermediate transfer member small. <P>SOLUTION: The image forming apparatus is equipped with the intermediate transfer member which transfers a toner image received and transferred from an image carrier to a recording medium, a cleaning means of removing a residue left on a surface of an image carrier after the toner image is transferred to the intermediate member from the surface, an electric charge imparting means of imparting electric charges of a predetermined polarity to the residue left on the intermediate transfer member, a cleaning roll whose peripheral surface abuts against the intermediate transfer member in an abutting state corresponding to the formation state of the toner image and which has a foaming layer on the peripheral surface, and a bias applying means of making a bias having the same polarity as the predetermined polarity operate on the residue having the electric charges of the predetermined polarity to move the residue from the intermediate transfer member onto an image carrier surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image composed of a fixed toner image on a recording medium.

  Conventionally, the surface of a charged photoreceptor is exposed to form an electrostatic latent image, the electrostatic latent image is developed to form a toner image, and the toner image is finally transferred onto a recording medium. An image forming apparatus is known. In such an image forming apparatus, an image adopting a two-stage transfer system in which the formed toner image is once transferred onto an intermediate transfer member, and the transferred toner image is then transferred onto a recording medium. There is also a forming device. In particular, in an image forming apparatus that forms a color image, it is necessary to form a multi-color toner image. Therefore, the toner image formed for each color is superimposed on an intermediate transfer member and then transferred onto a recording medium. Often.

  Residual toner that remains without being transferred adheres to the surface of the intermediate transfer member after the toner image is transferred onto the recording medium. In the image forming apparatus having the intermediate transfer member, the next image formation is performed. In many cases, a cleaning means for removing such residual toner is provided in preparation for the process. As such a cleaning method, a blade cleaning method in which a rubber edge is pressed to scrape off residual toner, or a fur brush cleaning method in which residual toner is removed using a brush (for example, Patent Documents 1 and 2). And a bias roller system (for example, see Patent Documents 3 to 8) in which cleaning is performed by electrically attracting residual toner by a cleaning roll to which a bias is applied.

Among these, since the bias cleaning method does not require a member that is in direct contact with the intermediate transfer member, wear of the intermediate transfer member due to friction, reduction of the driving speed of the intermediate transfer member during transfer, The burden on the intermediate transfer member is small, and it has desirable properties as a cleaning method.
JP-A-6-208319 Japanese Patent Laid-Open No. 6-314010 JP-A-10-333447 Japanese Patent Laid-Open No. 11-7226 JP-A-1-105980 JP-A-4-81785 JP 9-44007 A JP 2000-284606 A

  In addition to the residual toner, external additive particles previously added to the toner, such as a transfer aid and a cleaning aid, also remain attached to the surface of the intermediate transfer member. When the particles of the external additive are accumulated while adhering to the surface of the intermediate transfer member, image quality defects such as white streaks appear in the formed image. The external additive particles adhering to the surface of the intermediate transfer member have a strong force of adhering to the surface of the intermediate transfer member. If the bias cleaning method is applied as it is, the particles of the external additive adhering to the surface of the intermediate transfer member are sufficient. It is difficult to remove.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an image forming apparatus provided with a mechanism for removing external additives and residual toner remaining on the surface of an intermediate transfer member while suppressing a burden on the intermediate transfer member. To do.

In order to achieve the above object, an image forming apparatus of the present invention comprises:
In an image forming apparatus comprising an image carrier, forming a toner image on the surface of the image carrier, and transferring and fixing the toner image on a recording medium, thereby forming an image composed of a fixed toner image on the recording medium ,
An intermediate transfer member that receives the transfer of the toner image from the image carrier and transfers the transferred toner image to a recording medium;
Cleaning means for removing residues remaining on the surface of the image carrier after the toner image is transferred to the intermediate transfer member;
Charge imparting means for imparting a predetermined polarity of charge to the residue remaining on the intermediate transfer member;
A cleaning roll having a foam layer on the peripheral surface, the peripheral surface of which is in contact with the intermediate transfer member in a contact state according to the toner image formation state;
Bias applying means for applying a bias having the same polarity as the predetermined polarity to the residue having the charge of the predetermined polarity and transferring the residue from the intermediate transfer member to the surface of the image carrier. .

  Here, the aspect of the cleaning means may be any form, for example, an elastic blade, a fur brush, or a conductive roll. The “toner image formation state” generally represents the number of formed images, the formation density, and the like, and the “contact state” refers to the peripheral surface of the cleaning roll described above. The contact time and contact force when contacting the intermediate transfer member are collectively shown.

  According to the image forming apparatus of the present invention, the residual toner particles remaining on the intermediate transfer member are first aligned to a predetermined polarity by the charge applying unit. By doing so, the residual toner particles on the intermediate transfer member are transferred to the surface of the image carrier by the action of the bias. Residual toner particles transferred to the surface of the image carrier are removed from the surface by the cleaning means. Further, the residual external additive particles remaining on the intermediate transfer member are mechanically scraped by an edge (edge) that defines a void existing in the foam layer of the cleaning roll, and the residual external additive particles scraped off are It enters into the gap and aggregates in the gap. When the residual external additive particles are scraped off by the cleaning roll, if it is scraped more than necessary, the burden on the intermediate transfer member increases. Therefore, in the image forming apparatus of the present invention, depending on the toner image forming state, The contact between the cleaning roll and the intermediate transfer member is performed. As a result, the burden on the intermediate transfer member is reduced.

  When the residual external additive particles scraped off in this way are aggregated to some extent within the voids of the foamed layer, they naturally fall from the voids due to their own weight and return to the intermediate transfer member. Here, the residual external additive particles are also given a charge by the above-mentioned charge giving means, and further given a charge by frictional charging when scraping or agglomerating. For this reason, the aggregate of the residual external additive particles returned to the intermediate transfer member carries a considerable amount of charge, and moves to the surface of the image carrier by the action of the bias, and the residual external additive particles These aggregates are also removed from the surface by the cleaning means.

  Further, in the image forming apparatus of the present invention, there is no need to provide a recovery mechanism because the residue is removed by the cleaning means of the image carrier, even if no recovery mechanism is particularly provided as the cleaning means of the intermediate transfer member. The device can be small.

  In the image forming apparatus of the present invention, “the peripheral surface of the cleaning roll is in contact with the intermediate transfer member for a time corresponding to the formation state of the toner image”. The form is a preferred form.

  The burden on the intermediate transfer member due to the contact of the cleaning roll with the intermediate transfer member is often different depending on the toner image formation state during image formation. Therefore, according to the above-described form, the contact time between the cleaning roll and the intermediate transfer member is controlled according to the toner image formation state, so that the surface of the intermediate transfer member can be suppressed while suppressing the burden on the intermediate transfer member. The external additive and residual toner remaining on the top are removed.

  In the image forming apparatus of the present invention, “the toner image formation state is the number of recording media on which the image is formed, and the circumferential surface of the cleaning roll has a time corresponding to the number of recording media”. A configuration in which the peripheral surface is in contact with the intermediate transfer member during the period is also a preferable mode.

  The burden on the intermediate transfer member due to the contact of the cleaning roll with the intermediate transfer member depends greatly on the number of recording media on which images are formed. Therefore, according to the above-described embodiment, the contact time between the cleaning roll and the intermediate transfer member is controlled according to the number of recording media on which an image is formed, thereby suppressing the burden on the intermediate transfer member. However, the external additive and residual toner remaining on the surface of the intermediate transfer member are removed.

  Further, as the form of the image forming apparatus of the present invention, a form in which “the intermediate transfer member is an endless elastic belt member that circulates and moves in a predetermined direction” may be employed.

  The surface of the elastic belt member as described above often has considerable unevenness, and therefore, the residual external additive particles are difficult to be removed by entering the concave portion. Therefore, residual external additive particles can be sufficiently removed by using the cleaning roll.

  In the image forming apparatus of the present invention, “the charge applying unit applies a charge having a polarity opposite to the charge polarity of the toner having a predetermined charge polarity to the residue remaining on the intermediate transfer member. And a transfer means for transferring the toner image to the intermediate transfer body by applying a transfer bias having a polarity opposite to the charging polarity to the toner image formed on the surface of the image carrier. The form of “combined” is a preferable form.

  According to such a configuration, the polarity of the bias and the polarity of the transfer bias coincide with each other, and the bias applying unit also serves as the transfer unit, so that the apparatus can be made smaller.

  In the image forming apparatus of the present invention, “the cleaning roll has a hardness of 40 ° or more and 90 ° or less when the hardness of the peripheral surface is measured using an Asker-FP hardness meter manufactured by Kobunshi Keiki Co., Ltd. The form “is” is also a preferable form.

  Here, as a standard relating to the hardness of a general low hardness material, JIS E hardness, Asker C hardness, etc. of “JIS K6253: 97” are known. This is a standard used when measuring the hardness of a low-hardness material that is difficult to obtain a measurement value having a significant difference in hardness.

  By doing so, the foamed layer has a large number of voids having a size of 50 μm or more and 300 μm or less, and the residual external additive particles are scraped off by the edges (edges) defining the numerous voids. Increases scraping performance. Further, since the residual external additive particles aggregate in the gap having a size of 50 μm or more and 300 μm or less, the cohesiveness is also improved.

  According to the present invention, the external additive and residual toner remaining on the surface of the intermediate transfer member are removed while suppressing the burden on the intermediate transfer member.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a full-color image forming apparatus corresponding to an embodiment of the image forming apparatus of the present invention.

  An image forming apparatus 1 shown in FIG. 1 includes a photosensitive drum 10 and an intermediate transfer belt 20. The photosensitive drum 10 rotates clockwise about the rotation shaft 10a.

The intermediate transfer belt 20 is an endless belt member, and is arranged so as to be stretched around a plurality of support rolls and to come into contact with the surface 10 b of the photosensitive drum 10. The intermediate transfer belt 20 shown in FIG. 1 circulates counterclockwise following the rotating photosensitive drum 10. As the intermediate transfer belt, a synthetic resin such as polyimide, polycarbonate, polyester, polypropylene, or various rubbers containing an appropriate amount of a conductive agent such as carbon black is used, and its volume low efficiency is 10 ⁶ to 10 ^14. What is Ω · cm is used.

  The intermediate transfer belt 20 shown in FIG. 1 has elasticity made of a rubber material. Specifically, silicone rubber, NBR, H-NBR, chloroprene rubber, EPDM, urethane rubber, etc. are used as the main base material of the conductive elastic layer, and the material of the conductive protective layer is a frictional resistance reduction, Although it is not particularly limited as long as it can achieve the objectives of stability of electrical characteristics to the environment and improvement of residue cleaning performance by reducing surface roughness, polytetrafluoroethylene (PTFE), tetrafluoroethylene and perfluoroalkyl vinyl ether. It is possible to use a paint in which a fluororesin polymer such as a copolymer (PFA) or PVdF is dissolved and dispersed in an alcohol-soluble nylon, silicone resin, silane coupler, urethane resin emulsion or organic solvent. . These protective layers can be provided by dip coating, spray coating, electrostatic coating, roll coating, or the like. Furthermore, by performing surface treatment or polishing on the protective layer, release properties, conductivity, surface cleaning properties and the like can be improved.

  In addition, the intermediate transfer belt 20 is not limited to the one that rotates following the rotation of the photosensitive drum 10 as a driving source, but may be one that circulates and moves by a driving system different from the photosensitive drum 10. Further, not only the intermediate transfer belt but also a drum-shaped intermediate transfer member may be used.

  In the image forming apparatus 1, the primary transfer roll 40 is disposed at a position facing the photosensitive drum 10 with the intermediate transfer belt 20 interposed therebetween. The portion where the photosensitive drum 10 and the intermediate transfer belt 20 are in contact is the primary transfer position.

  A developing rotary 50 is disposed around the photosensitive drum 10 on the upstream side of the primary transfer position. The developing rotary 50 is provided with developing devices 51 to 54 that store colored toners of black (BK), yellow (Y), magenta (M), and cyan (C). Each color toner has a charging characteristic of charging the negative electrode, and each color toner is added with external additive particles smaller than toner particles such as a lubricant, a transfer aid, and a cleaning aid.

  Further, a charger 31, an exposure device 32, a cleaning device 33, and a static eliminator 34 are disposed around the photosensitive drum 10.

The charger 31 includes a charging roll 311 that rotates in contact with the surface 10 b of the photosensitive drum 10, a power supply 312 that supplies power to the charging roll 311, and a cleaning unit that removes deposits on the circumferential surface of the charging roll 311. 313. The power supply 312 applies a charging bias obtained by superimposing an AC voltage on a DC voltage to the charging roll 311. The charging roll 311 is a semiconductive one that rotates in contact with the photosensitive drum 10, and charges the photosensitive drum 10 by generating a discharge in a minute gap near the contact portion with the photosensitive drum 10. Instead of the charging roll 311, a blade-shaped charging member, a belt-shaped charging member, a brush-shaped charging member, a magnetic brush-shaped charging member, or the like is applicable. Further, the charging roll 311 and the blade-shaped charging member are not limited to the contact state with respect to the photosensitive drum 10, and may be arranged in a proximity state having a certain amount of gap (100 μm or less). A roll-shaped charging member, a blade-shaped charging member, and a belt-shaped charging member are composed of a material adjusted to an electric resistance (10 ³ Ω to 10 ⁸ Ω) effective as a charging member, and are a single layer. Or you may comprise from several layers. The material is mainly composed of synthetic rubber such as urethane rubber, silicone rubber, fluorine rubber, chloroprene rubber, butadiene rubber, EPDM, epichlorohydrin rubber, and elastomers such as polyolefin, polystyrene, vinyl chloride, conductive carbon, metal oxide, ion An appropriate amount of an optional conductivity imparting agent such as a conductive agent can be blended to develop and use an effective electrical resistance as a charging member. Furthermore, a resin such as nylon, polyester, polystyrene, polyurethane, silicone, etc. is made into a paint, and an appropriate amount of any conductivity imparting agent such as conductive carbon, metal oxide, ionic conductive agent, etc. is blended there, and the resulting paint is dipped. They can be laminated and used by any method such as spraying or roll coating.

The cleaning means 313 has brush fibers 3131 on one end side, and rotates around the other end as a rotation center. The cleaning means 313 is rotated so that the brush fibers 3131 can be brought into contact with and separated from the peripheral surface of the charging roll 311. At the time of image formation, the brush fibers 3131 are separated from the peripheral surface of the charging roll 311 so that an image is obtained. The brush fiber 3131 is brought into contact with the peripheral surface of the charging roll 311 at an arbitrary timing during non-formation to remove the deposits on the peripheral surface of the charging roll 311. The brush fibers 3131 of the cleaning means 313 shown in FIG. 1 are made of nylon, and the density of the brush fibers is preferably 15000 pieces / 6.45 cm ² or more.

  The charger 31 may employ a corotron charging method.

  The exposure device 32 irradiates exposure light toward the surface 10b of the photosensitive drum 10, and may use a light emitting diode, or an EL (Electro Luminescent). Also good.

  Further, a bias roll 60 as a secondary transfer member is provided around the intermediate transfer belt 20 on the downstream side of the primary transfer position, and further, at a position facing the bias roll 60 with the intermediate transfer belt 20 interposed therebetween. A backup roll 70 is provided. In the image forming apparatus 1, a position sandwiched between the bias roll 60 and the backup roll 70 is a secondary transfer position, and a recording medium such as paper or an OHP sheet is fed into the secondary transfer position. FIG. 1 shows a state in which the paper P is sent to the secondary transfer position.

The bias roll 60 shown in FIG. 1 includes a surface layer made of urethane rubber tube in which carbon is dispersed and an inner layer made of foamed urethane rubber in which carbon is dispersed. Is given. The bias roll 60 is formed such that the volume low efficiency is set to 10 ³ to 10 ¹⁰ Ω · cm, the diameter of the roll is set to, for example, 28 mm, and the hardness is set to, for example, 30 ° (Asuka C). .

  The image forming apparatus 1 shown in FIG. 1 receives four color image signals of yellow, magenta, cyan, and black. When these image signals are input, in the image forming apparatus 1, the surface 10b of the photosensitive drum 10 is uniformly charged by the charger 31 and then converted into a cyan image signal in the input image information. A corresponding laser beam is emitted from the exposure device 32 toward the photosensitive drum 10 to form an electrostatic latent image on the surface 10 b of the photosensitive drum 10, and the electrostatic latent image formed on the surface 10 b of the photosensitive drum 10. The image is developed by a developing device 54 containing cyan toner provided in the developing rotary 50 to form a cyan toner image on the surface 10 b of the photosensitive drum 10. Next, the cyan toner image on the photosensitive drum surface 10 b is primarily transferred to the intermediate transfer belt 20 at the primary transfer position. A primary transfer bias having a polarity opposite to the charging polarity of the toner is applied from the power source 41 to the primary transfer roll 40, and the cyan toner image formed on the surface of the photosensitive drum 10b is exposed to light at the primary transfer position. Transition from the body drum surface 10b to the intermediate transfer belt 20 is performed.

  On the surface 10b of the photosensitive drum 10 that has passed the primary transfer position, residual toner particles that could not be transferred to the intermediate transfer belt 20, external additive particles, discharge products generated during charging, etc. There are multiple types of residues. A cleaning device 33 shown in FIG. 1 is a device for removing these residues, and is downstream of the primary transfer position in the rotational direction of the photosensitive drum and upstream of the charger 31 in the rotational direction of the photosensitive drum. It is deployed at the side position. Here, the description of the cleaning device 33 shown in FIG. 1 will be continued with reference to FIG.

  FIG. 2 is a view of a part of the cleaning device shown in FIG. 1 as viewed from one end side of the rotating shaft of the photosensitive drum.

  The cleaning device 33 includes a housing 331, a cleaning blade 332, a lower seal 333, and a blocking member 334. The cleaning blade 332 has a rectangular shape that is long in the direction perpendicular to the paper surface of FIG. 2 (the direction in which the rotating shaft of the photosensitive drum 10 extends), but here, one end in the short direction is the tip. The other end is called the rear end. Further, the lower seal 333 and the blocking member 334 are also rectangular in a shape that is long in a direction perpendicular to the paper surface of FIG. 2, and these members 333 and 334 also have one end in the short direction as a tip. The other end is called the rear end. The lower seal 333 and the blocking member 334 are longer than the cleaning blade 332 in a direction perpendicular to the paper surface of FIG.

  The cleaning blade 332 has a rear end fixed to the housing 331, and an edge portion 3321 at the front end is in pressure contact with the surface 10 b of the photosensitive drum 10. When the photosensitive drum 10 rotates in a predetermined direction, the residue remaining on the surface 10 b of the photosensitive drum 10 after the toner image is transferred to the intermediate transfer belt 20 is scraped off from the surface 10 b by the edge portion 3321.

As the material of the cleaning blade 332, a rubber elastic body such as urethane rubber, silicon rubber, fluorine rubber, chloroprene rubber, butadiene rubber or the like can be used. Among them, it is preferable to use a polyurethane elastic body because of its excellent wear resistance. As the polyurethane elastic body, a polyurethane generally synthesized through an addition reaction between an isocyanate and a polyol and various hydrogen-containing compounds is used. As a polyol component, a polyether-based polyol such as polypropylene glycol or polytetramethylene glycol, Polyester polyols such as adipate polyols, polycaprolactam polyols, polycarbonate polyols, etc., and polyisocyanate components such as tolylene diisocyanate, 4,4′diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, toluidine diisocyanate, etc. Polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexane It is manufactured by preparing a urethane prepolymer using an aliphatic polyisocyanate such as xylmethane diisocyanate, adding a curing agent to the urethane prepolymer, pouring it into a predetermined mold, crosslinking and curing, and then aging at room temperature. ing. As the curing agent, a dihydric alcohol such as 1,4-butanediol and a trihydric or higher polyhydric alcohol such as trimethylolpropane or pentaerythritol are usually used in combination. The physical properties of the cleaning blade 332, such as hardness (JISA scale) 50 to 90, Young's modulus ^(kg / cm 2) ^40~90,100% modulus (kg / cm ²⁾ is 20～65,300% modulus ( kg / cm ² ) of 70 to 150, tensile strength (kg / cm ² ) of 240 to 500, elongation (%) of 290 to 500, rebound resilience (%) of 30 to 70, tear strength (kg / cm ² ) 25 to 75 and permanent elongation (%) of 4.0 or less can be used. Further, the pressure contact force of the cleaning blade 332 is preferably 10 to 60 (gf / cm), and the contact set angle is preferably 17 to 30 (°). The contact set angle referred to here is a tangent line between the cleaning blade 332 and the photosensitive drum 10 that extends downstream from the portion (edge portion 3321) of the photosensitive drum 10 in which the blade contacts. The angle between the two.

  As shown in FIG. 2, a rising portion 3312 that rises upward is provided on an edge of the bottom wall 3311 of the housing 331 that faces the photosensitive drum 10. The upright portion 3312 is at a position spaced from the surface 10 b of the photosensitive drum 10 and at a position below the edge portion 3321 of the cleaning blade 332. Both the lower seal 333 and the blocking member 334 have their rear ends fixed to the upright portion 3312. The housing 331 is provided with a discharge port (not shown), and a transfer auger 3313 is provided inside the housing 331.

  The blocking member 334 shown in FIG. 2 is made of polyethylene terephthalate (PET), the height position of the tip 3341 is higher than the height position of the edge portion 3321 of the cleaning blade 332, and the tip 3341 is At a position away from the cleaning blade 332. That is, a wrap region is formed between the blocking member 334 and the cleaning blade 332 with a space therebetween. Further, the blocking member 334 fixed to the rising portion 3312 has an opening 3342 in the vicinity of the rising portion 3312. The opening 3342 is a rectangular long hole provided along the longitudinal direction of the blocking member 334. The blocking member 334 may be provided with a plurality of openings.

  The lower seal 333 has a tip 3331 in contact with the surface 10 b of the photosensitive drum 10. That is, the lower seal 333 connects the upright portion 3312 and the photosensitive drum surface 10b at a position below the edge portion 3321 of the cleaning blade 332 and spaced from the surface 10b of the photosensitive drum 10; The length of the lower seal 333 in the extending direction of the rotation axis of the photosensitive drum 10 (length in the longitudinal direction) is approximately the same as the length of the blocking member 334 in the longitudinal direction. The lower seal 333 receives the residue scraped off by the cleaning blade 332.

  As shown in FIG. 2, a part of the surface 10 b of the photosensitive drum 10, a lower seal 333, and a blocking stopper are formed in a space extending from the edge portion 3321 of the cleaning blade 332 to the upstream side in the rotation direction of the photosensitive drum 10. A space S defined by the member 334 is included, and the residue scraped off by the cleaning blade 332 is stored in the space S. Lubricant particles contained in the residue stored in the space S and toner particles having a small particle diameter enter between the photosensitive drum surface 10b and the edge portion 3321 of the cleaning blade 332 as a lubricant. This prevents the edge portion 3321 from being worn or chipped. In particular, since the image forming apparatus 1 shown in FIG. 1 employs a contact charging method and applies a charging bias in which an AC voltage is superimposed on a DC voltage, the frictional force between the photosensitive drum surface 10b and the edge portion 3321 is applied. However, by providing the cleaning device 33 shown in FIG. 2, the increase in the frictional force can be effectively suppressed.

  In addition, in the image defect due to the contamination of the charging roll 311, the nonuniformity of the charge level due to the nonuniformity of the contamination of the charging roll 311 is also important, and it is not just a problem of the absolute value of charging. Therefore, even if there is a contamination that lowers the potential of the photosensitive drum 10 to some extent, if the level of reduction is uniform, there is no problem in practical use. However, particularly when a single image is output, the charging roll 311 is also soiled easily, and the portion corresponding to the image is liable to be deteriorated, and charging unevenness is likely to occur. By storing the residue in the space S, it is possible to supply toner and external additive particles having a small particle size, which is a stain component of the charging roll 311, to the non-image portion. It is possible to make the degree of dirt and adhered matter almost uniform.

  Further, by adding lubricant particles to the toner, the lubricant can be supplied to the photosensitive drum 10 together with image formation, and can be fixed to the photosensitive drum 10 by the cleaning blade 332. As a result, it is possible to control excessive migration of the lubricant while supplying a small amount of lubricant to the charging roll 311 that is in contact with the photosensitive drum 10, and it is assumed that excessive lubricant adheres to the charging roll 311. However, the lubricant adhering to the charging roll 311 can be removed by the cleaning means 313 of the charging roll 311 shown in FIG. Control is possible. Further, by forming a small amount of lubricant film on the peripheral surface of the charging roll 311, it is possible to improve the foreign matter removability of the peripheral surface, and long-term deterioration of charging property due to excessive foreign matter adhesion and sticking. Suppression is possible across.

  The residue stored in the space S is discharged into the housing 331 from an opening 3342 provided in the blocking member 334, and the amount of residue stored in the space S is controlled and the residue in the space S is controlled. The residue is replaced with the newly scraped one. The residue discharged into the housing 331 is transferred to a discharge port (not shown) by a transfer auger 3313.

  Residual charges are removed from the photosensitive drum 10 cleaned by the cleaning device 33 by the static eliminator 34.

  Subsequently, this time, a magenta toner image is similarly formed on the surface 10b of the photosensitive drum 10, and this magenta toner image is overlapped with the cyan toner image previously primary-transferred at the primary transfer position. Primary transfer is performed on the intermediate transfer belt 20.

  Thereafter, a yellow toner image and a black toner image are sequentially formed, and primary transfer is sequentially performed at the primary transfer position so as to overlap with the toner image previously transferred to the intermediate transfer belt 20. By doing so, toner images are formed on the intermediate transfer belt 20 so as to overlap one another in the order of cyan, magenta, yellow, and black from the belt surface side.

  Subsequently, the overlapping toner image is secondarily transferred onto a sheet at a secondary transfer position sandwiched between the bias roll 60 and the backup roll 70. A secondary transfer bias is applied to the bias roll 60 from the power supply 61, and the overlapping toner images are transferred from the intermediate transfer belt 20 to the paper P at the secondary transfer position. Thus, the toner image is transferred onto the paper P, and the paper P on which the toner image is transferred is sent to a fixing device (not shown). In the fixing device, by passing a sheet carrying an unfixed toner image through a predetermined nip region, heat and pressure are applied to the unfixed toner image to fix the unfixed toner image on the sheet. Thus, an image composed of a fixed toner image is formed on the paper P.

  Further, on the surface of the intermediate transfer belt 20 that has passed the secondary transfer position, there are residuals such as residual toner particles and external additive particles that could not be transferred to the paper P. The image forming apparatus 1 shown in FIG. 1 has a belt cleaner device 80 at a position downstream of the secondary transfer position in the intermediate transfer belt circulation movement direction and upstream of the primary transfer position in the intermediate transfer belt circulation movement direction. I have. The belt cleaner 80 includes a roll brush 81, a power source 82, and a cleaning roll 83. Further, a backup roll 89 is provided at a position facing the roll brush 81 and a position facing the cleaning roll 83 with the intermediate transfer belt 20 in between. Both of the roll brush 81 and the cleaning roll 83 are detachable from the intermediate transfer belt 20. The position of the roll brush 81 and the cleaning roll 83 is not changed, and the circulation path of the intermediate transfer belt 20 is changed so that the roll brush 81 and the cleaning roll 83 can be moved toward and away from the intermediate transfer belt 20 relatively. It may be a thing.

  The roll brush 81 has hairs (brush fibers) 811 extending radially from a rotation shaft extending in the width direction of the endless intermediate transfer belt 20. Examples of the fibers used for the hair 811 include resin fibers such as nylon, acrylic, polyolefin, and polyester, and commercially available products such as Beltron (manufactured by Kanebo), SA-7 (manufactured by Toray Industries, Inc.), UU nylon (manufactured by Unitika) Goods can be used. The bristles 811 are conductive. Examples of a method for imparting conductivity to the bristles 811 include a method of blending a fiber with a conductive powder or an ionic conductive material, a method of forming a conductive layer inside or outside the fiber, and the like. A bias having a polarity opposite to the charging polarity of the toner is applied from the power source 82 to the bristles 811 of the roll brush 81. That is, a positive bias is applied. The positive polarity bias may be a DC bias or an AC bias, but here, a bias obtained by superimposing an AC voltage on a DC voltage is used. Bipolar residual toner particles are present on the surface of the intermediate transfer belt 20 that has passed through the secondary transfer position, but a positive bias is applied to the bristles 811 of the roll brush 81 in contact with the surface of the intermediate transfer belt 20. When applied, the residual toner particles on the intermediate transfer belt 20 are imparted with a positive charge, and the residual toner particles are aligned with positive polarity. Therefore, this roll brush 81 corresponds to an example of the charge applying means referred to in the present invention. Further, even if there are residual toner particles firmly adhered to the surface of the intermediate transfer belt 20, the residual toner particles are peeled off from the surface of the intermediate transfer belt by the AC voltage included in the positive polarity bias. .

In place of the roll brush 81, a roll body may be used. The roll body referred to here is one in which a conductive cylinder is provided around a rotation axis extending in the width direction of the endless intermediate transfer belt 20. The rotating shaft is made of a conductive material such as iron, nickel-plated iron, copper alloy, and stainless steel. An example of the conductive cylindrical body is a two-layer structure composed of an elastic layer and a surface layer. The elastic layer is composed of epichlorohydrin rubber, polyether urethane rubber, polyester urethane rubber, chloroprene rubber, NBR, EPDM blend NBR rubber, SBR rubber, butyl rubber, etc. with various alkylammonium salts having an alkali metal and quaternary ammonium salt structure. The surface layer is a layer that covers the peripheral surface of the elastic layer and constitutes the outermost surface of the conductive cylindrical body. The binder resin used for this surface layer is polyester, polyamide, polyurethane, melamine resin, acrylic resin such as PMMA or PMBA, polyvinyl butyral, polyvinyl acetal, polyarylate, polycarbonate, phenoxy resin, polyurea, polyvinyl acetate, etc. Can give. The resistance value of the roll body is desirably 10 ⁵ to 10 ¹¹ Ω · cm in terms of volume resistance, but is not limited thereto. Moreover, you may use a hard roll body like a metal roll. The amount of biting of the roll body into the intermediate transfer belt 20 may be set as appropriate within a range of load that does not cause a problem in the circulation and movement of the intermediate transfer belt 20, for example, 0.2 mm to 0.8 mm. You only have to set it.

  The cleaning roll 83 has a foam layer 831 formed by foaming an elastic material on the peripheral surface, and the rubber hardness of the peripheral surface is 40 when measured using an Asker-FP hardness meter manufactured by Kobunshi Keiki Co., Ltd. It is preferable that the angle is from 90 ° to 90 °. For example, it can be formed by foaming silicone rubber or urethane rubber. The cleaning roll 83 rotates with a peripheral speed difference with respect to the intermediate transfer belt 20. When the cleaning roll 83 is rotated in a state where the peripheral surface of the cleaning roll 83 is in contact with the surface of the intermediate transfer belt 20, Residual external additive particles remaining on the intermediate transfer belt 20 are mechanically scraped by edges (edges) that define voids present in the foam layer 831 of the cleaning roll 83, and the residual external additive particles thus scraped off are It enters into the gap and aggregates in the gap. By setting the rubber hardness of the peripheral surface of the cleaning roll 83 within the above range, the foam layer 831 of the cleaning roll 83 has many voids with a size of 50 μm or more and 300 μm or less, and residual external additive particles Since it is scraped off by the edges that define the large number of voids, the scraping property is enhanced. Further, since the residual external additive particles aggregate in the gap having a size of 50 μm or more and 300 μm or less, the cohesiveness is also improved. When the residual external additive particles agglomerate to some extent in the gap, they naturally fall from the gap due to their own weight and return to the intermediate transfer belt 20.

  If the cleaning roll 83 is in contact with the intermediate transfer belt 20 for a long time, the friction with the cleaning roll 83 imposes a burden on the intermediate transfer body 20 such as wear of the intermediate transfer body 20 or reduction of the rotation speed of the intermediate transfer body 20. growing. Generally, the amount of residual external additive increases as the amount of developer used increases, and therefore the amount of residual external additive increases as the number of output sheets increases and the density of the formed image increases. . Therefore, in the image forming apparatus 1 shown in FIG. 1, the control is performed such that the contact time between the cleaning roll 83 and the intermediate transfer belt 20 becomes longer as the number of output sheets when continuous output is performed is increased. Therefore, it is possible to perform sufficient cleaning while reducing the burden on the device. Such control is performed by the control unit 90 shown in FIG. 1 that controls the entire image forming apparatus 1.

  Hereinafter, the operation of the image forming apparatus 1 when removing the residual toner and the residual external additive will be described.

  FIG. 3 is a flowchart showing the operation of the image forming apparatus shown in FIG. 1 when removing the residual toner and the residual external additive.

  When the operation of continuously outputting images and characters on a plurality of sheets is started (step S1), the control unit 90 shown in FIG. 1 counts the number of output sheets (step S2). During this output work, the controller 90 keeps both the roll brush 81 and the cleaning roll 83 away from the intermediate transfer belt 20 until the output work is completed. When the output operation is completed (step S3; Yes), the control unit 90 brings the roll brush 81 into contact with the intermediate transfer belt 20 while the cleaning roller 83 is separated from the intermediate transfer belt 20, and a positive polarity bias is supplied from the power source 82. It is applied to the hair 811 of the roll brush 81. By this application, the residual toner and the residual external additive particles on the intermediate transfer belt 20 are made positive by the roll brush 81. Further, the control unit 90 causes the power supply 41 of the primary transfer roll 40 to apply a positive bias to the primary transfer roll 40, so that residual toner and residual external additive having a positive charge on the intermediate transfer belt 20. For such a residue, an electrostatic force that is transferred from the intermediate transfer belt 20 to the photosensitive drum surface 10b is generated. Residual toner among the residuals is transferred from the intermediate transfer belt 20 to the photosensitive drum surface 10b by such bias application, and is scraped off and removed from the surface 10b of the photosensitive drum surface 10b by the cleaning blade 332. However, the residual external additive particles have a strong force of adhering to the surface of the intermediate transfer belt 20, and most of the residual external additive particles remain on the intermediate transfer belt 20 even when a bias is applied. Therefore, it is necessary to scrape the external additive particles adhering to the surface of the intermediate transfer belt 20 from the intermediate transfer belt 20. For this purpose, the cleaning roll 83 is brought into contact with the intermediate transfer belt 20. However, if the contact time of the cleaning roll 83 is longer than necessary, the burden on the intermediate transfer member, such as wear of the intermediate transfer member, increases. Therefore, in the image forming apparatus 1 shown in FIG. It is controlled according to the number of continuous output sheets. Hereinafter, such control of the contact time will be described.

  After the residual external additive particles are charged by the roll brush 81, the control unit 90 separates the roll brush 81 from the intermediate transfer belt 20, and determines the number of sheets output during the output operation ( Step S4).

  If the number of output sheets is less than 10 (step S5), the cleaning roll 83 is brought into contact with the intermediate transfer belt 20 for 3 seconds (step S6). By this contact, the residual external additive particles on the intermediate transfer belt 20 are scraped off by the cleaning roll 83 as described above, and return to the intermediate transfer belt 20 as aggregates.

  Similarly, when the number of output sheets is 10 or more and less than 50 sheets (step S7), the cleaning roll 83 is brought into contact with the intermediate transfer belt 20 for 7 seconds (step S8), and the number of output sheets is determined. If the number of output sheets is 50 or more and less than 100 sheets (step S9), the cleaning roller 83 is contacted for 12 seconds (step S10), and the number of output sheets is 100 sheets or more (step S10). In S11), the cleaning roll 83 is contacted for 15 seconds (step S12). In any of these steps S8, S10, and S12, the residual external additive particles on the intermediate transfer belt 20 are scraped off by the cleaning roll 83 to become aggregates and return to the intermediate transfer belt 20. .

  The residual external additive particles before becoming aggregates have a large adhesion force to the intermediate transfer belt 20 and a small amount of electric charge is carried by one particle. In this state, the intermediate transfer belt is caused by electrostatic force. It is difficult to shift from 20 to the photosensitive drum surface 10b. However, since the residual external additive particles that have become aggregates have a small adhesion to the intermediate transfer belt 20 and also have a large amount of charge as a whole aggregate, the electrostatic force exerts on the surface 10b of the photosensitive drum. It is possible to migrate. In addition, since the residual external additive particles are given a certain amount of electric charge due to frictional electrification when they are scraped or agglomerated, the electric charge more than that given by the roll brush 81 by being scraped by the cleaning roll 83. Have a quantity.

  The aggregate of residual external additive particles having a large amount of electric charge in this manner is transferred to the surface of the photosensitive drum 10b as in the case of the residual toner described above, and finally cleaned in the same manner as the residual toner particles. The blade 332 is scraped and removed from the photosensitive drum surface 10b.

  Finally, the control unit 90 returns the counted number of output sheets to initialization (that is, zero) (step S14), and the operation of removing the residual toner and the residual external additive is completed.

  By such control, the residual external additive and the residual toner are removed from the surface of the intermediate transfer belt 20 while suppressing the burden on the intermediate transfer belt 20.

  Here, in this image forming apparatus 1, the belt cleaner device 80 that is a cleaning unit for the intermediate transfer belt 20 does not need a collecting mechanism for collecting the residual external additive and the residual toner. Has been realized.

  Further, in the operation of removing the residual external additive, even if there is an aggregate that does not move to the photosensitive drum surface 10b due to the action of the positive polarity bias, it is peeled off from the intermediate transfer belt 20. It does not fall from the intermediate transfer belt 20 and cause image quality defects.

  Next, the developing devices 51 to 54 shown in FIG. 1 will be described in detail. These developing units 51 to 54 contain colored toner to which external additive particles are added as described above. The toner accommodated in these developing devices 51 to 54 is not particularly limited by the production method. For example, a binder resin and a colorant, a release agent, and a charge control agent as necessary are kneaded, pulverized, A kneading and pulverizing method for classifying, a method for changing the shape of particles obtained by the kneading and pulverizing method with a mechanical impact force or thermal energy, and a dispersion formed by emulsion polymerization of a polymerizable monomer of a binder resin Is mixed with a colorant, a release agent and, if necessary, a dispersion of a charge control agent, and agglomerated and heat-fused to obtain toner particles, and a polymerization property for obtaining a binder resin. Suspension polymerization method in which a monomer and a colorant, a release agent and, if necessary, a solution such as a charge control agent are suspended in an aqueous solvent for polymerization, a binder resin and a colorant, a release agent, and if necessary Obtained by suspending a solution such as a charge control agent in an aqueous solvent and granulating the solution. The can be used. In addition, a known method such as a production method in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to give a core-shell structure can be used, but from the viewpoint of shape control and particle size distribution control Suspension polymerization method, emulsion polymerization aggregation method, and dissolution suspension method, which are produced from an aqueous solvent, are preferred, and emulsion polymerization aggregation method is particularly preferred.

The toner particles include a binder resin, a colorant, a release agent, and the like. If necessary, silica or a charge control agent may be used. The volume average particle diameter is preferably in the range of 2 to 12 μm, and more preferably in the range of 3 to 9 μm. Further, a toner having an average spherical coefficient of 100 × ((ML ² / A) × 4π: ML is the absolute maximum length of toner particles, and A is the projected area of the toner particles) is in the range of 115 to 140. As a result, an image with high development, transferability and high image quality can be obtained.

  Binder resins used include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; Α-methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Examples of vinyl polymers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene- Mention may be made of maleic anhydride copolymers, polyethylene, polypropylene and the like. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  In addition, toner colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green oxa. Rate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

  Typical examples of the release agent include low molecular polyethylene, low molecular polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  Further, the toner accommodated in each of the developing devices 51 to 54 shown in FIG. 1 is one in which lubricant particles are added as a kind of external additive particles. Lubricants such as solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids, fatty acid metal salts; low molecular weight polyolefin particles such as polypropylene, polyethylene, polybutene; silicones having a softening point upon heating; oleic acid amide, Elca Aliphatic amides such as acid amide, ricinoleic acid amide, stearic acid amide; plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax Minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, and petroleum waxes; and their modified products can be used alone or in combination. good. In particular, it is preferable to use a fatty acid metal salt, specifically zinc stearate, which has a high friction reducing effect due to its cleavage property. The amount of zinc stearate added is preferably 0.01 to 2.0% by weight, more preferably 0.05 to 0.5% by weight. When the amount is less than 0.01%, sufficient lubrication effect cannot be exhibited. When the amount is more than 2.0%, the amount of adhesion to the photosensitive drum 10 becomes excessive, and image flow occurs under high temperature and high humidity. In addition, the charging property of the toner itself is adversely affected.

  Here, when the amount of zinc stearate on the surface 10b of the photosensitive drum in contact with the charging roll 311 is expressed by the Zn coverage by XPS analysis, the range of 0.05% to 30% is preferable, and 1% to 15%. The following ranges are more preferable. Here, since the XPS analysis is an analysis of the extreme surface, the analysis value is saturated with respect to the coating amount. Therefore, the Zn coverage was calculated with the saturated amount as 100%. When the coverage is less than 0.01%, the supply of zinc stearate to the charging roll 311 becomes insufficient, and foreign substances such as toner and silica cannot be sufficiently removed by the cleaning unit 313. In addition, sticking of adherents is likely to occur, and charging failure is likely to occur during long-term running. On the other hand, when the coverage is more than 70%, the amount of zinc stearate attached on the peripheral surface of the charging roll becomes excessive, and charging failure and charging unevenness are likely to occur.

  In addition, the toner accommodated in each of the developing devices 51 to 54 shown in FIG. 1 includes inorganic particles, organic particles, and inorganic particles in the organic particles for the purpose of removing deposits and deteriorated materials on the surface 10b of the photosensitive drum 10. Although composite particles to which particles are attached can be added, inorganic particles that are excellent in abrasiveness are particularly preferable. Inorganic particles include silica, alumina, titania, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, Various inorganic oxides such as manganese oxide, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, and boron nitride, nitrides, borides, and the like are preferably used. Moreover, titanium coupling agents such as tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecyl benzene sulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, γ- (2-amino) Ethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane Hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane The treatment may be performed with a silane coupling agent such as run, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, and p-methylphenyltrimethoxysilane. Further, hydrophobic treatment with a higher fatty acid metal salt such as silicone oil, aluminum stearate, zinc stearate, calcium stearate can be preferably performed.

  Examples of the organic particles include styrene resin particles, styrene acrylic resin particles, polyester resin particles, and urethane resin particles. If the particle size is too small, the polishing ability is insufficient, and if it is too large, the surface of the photosensitive drum is likely to be damaged. Therefore, the average particle size is in the range of 5 to 1000 nm, preferably in the range of 5 to 800 nm. More preferably, the one in the range of 5 to 700 nm is used. Moreover, it is preferable that the sum with the addition amount of the said lubricant is 0.6 mass% or more.

  Other inorganic oxides added to the toner are small-diameter inorganic oxides having a primary particle size of 40 nm or less for powder flowability, charge control, etc. Mention may be made of large-diameter inorganic oxides. Known inorganic oxide particles can be used, but it is preferable to use silica and titanium oxide in combination for precise charge control. Further, the surface treatment of the small-diameter inorganic particles increases the dispersibility and increases the effect of improving the powder fluidity.

  The toner accommodated in each of the developing devices 51 to 54 shown in FIG. 1 can be manufactured by mixing the toner particles and the external additive with a Henschel mixer or a V blender. In addition, when the toner particles are produced by a wet method, external addition can be performed by a wet method.

  Further, the toner accommodated in each of the developing devices 51 to 54 shown in FIG. 1 is mixed with a carrier. As the carrier, iron powder, glass beads, ferrite powder, nickel powder, or those having a resin coating on the surface thereof are used. Further, the mixing ratio of the carrier and the toner can be set as appropriate.

  Next, a photosensitive drum that can be used as the photosensitive drum 10 shown in FIG. 1 will be described in detail. As this photoconductor drum, one obtained by laminating a photosensitive layer including a charge generation layer and a charge transport layer on the surface of a conductive substrate on a cylinder can be used. The conductive base material may be a metal drum such as aluminum, copper, iron, stainless steel, zinc, nickel, or aluminum, copper, gold, silver, platinum, palladium, titanium, sheet, paper, plastic, or glass. Metals such as nickel-chrome, stainless steel, copper, and indium may be vapor-deposited, conductive metal compounds such as indium oxide and tin oxide may be vapor-deposited, metal foil may be laminated, or carbon black Indium, tin oxide, antimony oxide powder, metal powder, copper iodide and the like are dispersed in a binder resin and applied, and then conductively treated. The shape of the conductive substrate is not limited to a drum shape, and may be a sheet shape or a plate shape. In addition, when the conductive base material is a metal pipe, the surface may be left as it is, and in advance processing such as mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing, etc. It may be done.

  An undercoat layer may be formed on the surface of the conductive substrate as desired. Materials used for this undercoat layer include zirconium chelate compounds, zirconium alkoxide compounds, organic zirconium compounds such as zirconium coupling agents, titanium chelate compounds, titanium alkoxide compounds, organic titanium compounds such as titanate coupling agents, aluminum chelate compounds, In addition to organoaluminum compounds such as aluminum coupling agents, antimony alkoxide compounds, germanium alkoxide compounds, indium alkoxide compounds, indium chelate compounds, manganese alkoxide compounds, manganese chelate compounds, tin alkoxide compounds, tin chelate compounds, aluminum silicon alkoxide compounds, Aluminum titanium alkoxide compound, aluminum zirconium alkoxy Compounds, organometallic compounds such as, in particular an organic zirconium compound, an organic titanyl compound, since the organic aluminum compound to residual potential indicates a satisfactory electrophotographic properties lower, are preferably used. Also, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-2-methoxyethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyl Triethoxysilane, γ-chloropropyltrimethoxysilane, γ-2-aminoethylaminopropyltrimethoxysilane, γ-mercapropropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, β-3,4-epoxycyclohexyltri It can be used by containing a silane coupling agent such as methoxysilane. Furthermore, polyvinyl alcohol, polyvinyl methyl ether, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, polyamide, polyimide, casein, gelatin, polyethylene, conventionally used for the undercoat layer Known binder resins such as polyester, phenol resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, polyvinyl pyrrolidone, polyvinyl pyridine, polyurethane, polyglutamic acid, and polyacrylic acid can also be used. These mixing ratios can be appropriately set as necessary.

  Any known charge generating material can be used as the charge generating material contained in the charge generating layer. For infrared light, phthalocyanine pigments, squarylium, bisazo, trisazo, perylene, dithioketopyrrolopyrrole, and for visible light, condensed polycyclic pigments, bisazo, perylene, trigonal selenium, dye-sensitized metal oxide particles and the like are used. Among these, a particularly excellent performance is obtained, and a phthalocyanine pigment is used as a charge generating material that is preferably used. By using this, it is possible to obtain an electrophotographic photosensitive member having particularly high sensitivity and excellent repetitive stability. In addition, phthalocyanine pigments generally have several crystal forms, and any of these crystal forms can be used as long as it is a crystal form capable of obtaining a sensitivity suitable for the purpose. Particularly preferred charge generating materials include chlorogallium phthalocyanine, dichlorotin phthalocyanine, hydroxygallium phthalocyanine, metal-free phthalocyanine, oxytitanyl phthalocyanine, chloroindium phthalocyanine, and the like.

  Phthalocyanine pigment crystals are produced by a known method, and phthalocyanine pigments are mechanically dry-pulverized with an automatic mortar, planetary mill, vibration mill, CF mill, roller mill, sand mill, kneader, etc. It can be produced by wet pulverization using a mortar, sand mill, kneader or the like. Solvents used in the above treatment are aromatics (toluene, chlorobenzene, etc.), amides (dimethylformamide, N-methylpyrrolidone, etc.), aliphatic alcohols (methanol, ethanol, butanol, etc.), aliphatic polyvalents. Alcohols (ethylene glycol, glycerin, polyethylene glycol, etc.), aromatic alcohols (benzyl alcohol, phenethyl alcohol, etc.), esters (acetic ester, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, etc.), dimethyl sulfoxide, ether (Diethyl ether, tetrahydrofuran, etc.), several mixed systems, and mixed systems of water and these organic solvents. The solvent used is used in an amount of 1 to 200 parts, preferably 10 to 100 parts, based on the pigment crystals. The treatment temperature is −20 ° C. to the boiling point of the solvent, preferably −10 to 60 ° C. In addition, grinding aids such as sodium chloride and sodium nitrate can be used during grinding. The grinding aid may be used 0.5 to 20 times, preferably 1 to 10 times the pigment. Further, phthalocyanine pigment crystals produced by a known method can be controlled by combining acid pasting or acid pasting with dry grinding or wet grinding as described above. As an acid used for acid pasting, sulfuric acid is preferable, and a sulfuric acid having a concentration of 70 to 100%, preferably 95 to 100% is used, and a dissolution temperature is -20 to 100 ° C, preferably -10 to 60 ° C. Is set. The amount of concentrated sulfuric acid is set in the range of 1 to 100 times, preferably 3 to 50 times the weight of the phthalocyanine pigment crystals. As a solvent to be precipitated, water or a mixed solvent of water and an organic solvent is used in an arbitrary amount. The temperature for precipitation is not particularly limited, but it is preferably cooled with ice or the like in order to prevent heat generation.

  The binder resin used for the charge generation layer can be selected from a wide range of insulating resins. It can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Preferred binder resins include polyvinyl acetal resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin Insulating resin such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin can be used, but is not limited thereto. These binder resins can be used alone or in admixture of two or more. Of these, polyvinyl acetal resin is particularly preferably used.

  In addition, the blending ratio (weight ratio) between the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10. The solvent for adjusting the coating solution can be arbitrarily selected from known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers, esters, and the like. . For example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Usual organic solvents such as methylene chloride, chloroform, chlorobenzene, and toluene can be used. Moreover, the solvent used for these dispersion | distribution can be used individually or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as the mixed solvent.

  As a dispersion method, methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used. Furthermore, as a coating method used when providing this charge generation layer, a normal method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. Can be used.

  When dispersing, it is effective for high sensitivity and high stability that the particles have a particle size of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

  Further, the charge generating material can be subjected to a surface treatment for improving the stability of electrical characteristics and preventing image quality defects. A coupling agent or the like can be used as the surface treatment agent, but is not limited thereto. Examples of coupling agents used for the surface treatment include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycol. Sidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- ( Examples include silane coupling agents such as aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and γ-chloropropyltrimethoxysilane. Among these, silane coupling agents that are particularly preferably used are vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxy Examples of the silane coupling agent include silane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

  Zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, zirconium naphthenate, lauric acid Organic zirconium compounds such as zirconium, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide can also be used. Tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate Organic titanium compounds such as ethyl ester, titanium triethanolamate, polyhydroxytitanium stearate, aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate, aluminum diisopropylate, aluminum tris (ethyl acetoacetate An organoaluminum compound such as) can also be used.

  Various additives may be added to the charge generation layer coating solution in order to improve electrical characteristics and image quality. Additives include quinone compounds such as chloranil, bromoanil and anthraquinone, tetracyanoquinodimethane compounds, fluorenones such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone Compounds, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-bis (4-naphthyl) -1,3,4-oxadi Azoles, oxadiazole compounds such as 2,5-bis (4-diethylaminophenyl) 1,3,4 oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5 ′ tetra-t-butyl Electron transporting substances such as diphenoquinone compounds such as diphenoquinone, electron transporting pigments such as polycyclic condensation systems and azo systems, zirconium chelate compounds, tita Umukireto compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, there can be used a known material such as a silane coupling agent. Examples of silane coupling agents include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltri Methoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)- γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and the like. Examples of zirconium chelate compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, naphthene. Zirconate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of titanium chelate compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, Examples include titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, and polyhydroxytitanium stearate.

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.

  These compounds can be used alone or as a mixture or polycondensate of a plurality of compounds.

  Furthermore, as a coating method used when providing this charge generation layer, a normal method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. Can be used.

  As the charge transport material contained in the charge transport layer, any known material can be used, but the following can be exemplified. Oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [pyridyl- (2)]-3 Pyrazoline derivatives such as-(p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, tri (P-methyl) phenylamine, N, N'-bis (3,4-dimethylphenyl) biphenyl Aromatic tertiary amino compounds such as -4-amine, dibenzylaniline, 9,9-dimethyl-N, N′-di (p-tolyl) fluoren-2-amine, N, N′-diphenyl-N, Aromatic tertiary diamino compounds such as N′-bis (3-methylphenyl)-[1,1-biphenyl] -4,4′-diamine, 3- (4′dimethyla 1,2,4-triazine derivatives such as nophenyl) -5,6-di- (4′-methoxyphenyl) -1,2,4-triazine, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4-diphenyl Hydrazone derivatives such as aminobenzaldehyde-1,1-diphenylhydrazone, [p- (diethylamino) phenyl] (1-naphthyl) phenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2, Benzofuran derivatives such as 3-di (p-methoxyphenyl) -benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N′-diphenylaniline, enamine derivatives, N-ethylcarbazole, etc. Carbazole derivatives, poly-N-vinylcarba Hole transport materials such as sol and its derivatives. Quinone compounds such as chloranil, bromoanil, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2- ( 4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4-oxadiazole, 2,5 -Oxadiazole compounds such as bis (4-diethylaminophenyl) 1,3,4 oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5′tetra-t-butyldiphenoquinone, etc. Examples thereof include an electron transport material such as a diphenoquinone compound, or a polymer having a group comprising the above compound in the main chain or side chain. These charge transport materials can be used alone or in combination of two or more.

  Any binder resin can be used for the charge transport layer as long as it is known, but an electric insulating film-forming resin is preferred. For example, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-acetic acid Vinyl copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-carbazole, polyvinyl butyral, polyvinyl formal, polysulfone, Casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenol resin, polyamide, carboxymethyl cellulose, vinylidene chloride polymer wax, polyurethane Although the like, but is not limited to these. These binder resins are used singly or in combination of two or more. In particular, polycarbonate resins, polyester resins, methacrylic resins, and acrylic resins are compatible with charge transport materials, soluble in solvents, and strong. Excellent and preferably used. The mixing ratio (weight ratio) between the binder resin and the charge transport material can be arbitrarily set in any case, but attention must be paid to a decrease in electrical characteristics and a decrease in film strength. The thickness of the charge transport layer is 5 to 50 μm, preferably 10 to 40 μm. Furthermore, as a coating method used when providing this charge transport layer, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. Can be used. As a solvent used for coating, usual organic solvents such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene can be used alone or in admixture of two or more.

  In addition, additives such as antioxidants and light stabilizers may be added to the photosensitive layer for the purpose of preventing deterioration of the photosensitive drum due to ozone, oxidizing gas, or light and heat generated in the image forming apparatus. Can do.

  Examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and their derivatives, organic sulfur compounds, and organic phosphorus compounds.

  Specific examples of antioxidants include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol, styrenated phenol, n-octadecyl-3- (3 ′, 5′-di -T-butyl 4'-hydroxyphenyl) -propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2-t-butyl-6- (3'-t-butyl) -5'-methyl-2'-hydroxybenzyl) -4-methylphenyl acrylate, 4,4'-butylidene-bis- (3-methyl-6-tert-butyl-phenol), 4,4'-thio-bis -(3-methyl 6-tert-butyl phenol), 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetrakis- [methylene 3- (3 ′, 5′-di-tert-butyl-4′-hydroxy-phenyl) propionate] -methane, 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5] -Methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane. Among hindered amine compounds, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2, 2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4, -Benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine heavy succinate Compound, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diimyl} {(2,2,6,6-tetramethyl- 4-piperidyl) imino} hexamethylene {(2,3,6,6-tetramethyl-4-piperidyl) imino}], 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2- n-Butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N— (1,2,2,6,6, -pentamethyl-4piperidyl) amino] -6-chloro-1,3,5-triazine condensate and the like. Dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythritol-tetrakis- ( β-lauryl-thiopropionate), ditridecyl-3,3′-thiodipropionate, 2-mercaptobenzimidazole and the like. Examples of organophosphorus antioxidants include trisnonylphenyl phosfete, triphenyl phosfeft, and tris (2,4-di-t-butylphenyl) -phosfte.

  Organic sulfur-based and organic phosphorus-based antioxidants are referred to as secondary antioxidants, and a synergistic effect can be obtained by using them together with primary antioxidants such as phenols or amines.

  Examples of the light stabilizer include benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine derivatives.

  Examples of the benzophenone light stabilizer include 2-hydroxy-4-methoxy benzophenone, 2-hydroxy-4-octoxy benzophenone, and 2,2'-di-hydroxy-4-methoxy benzophenone. 2-(-2′-hydroxy-5′methyl phenyl-)-benzotriazole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″) as a benzotriazole-based light stabilizer , 6 ″ -tetra-hydrophthalimido-methyl) -5′-methylphenyl] -benzotriazole, 2-(-2′-hydroxy-3′-t-butyl 5′-methylphenyl-)-5-chlorobenzo Triazole, 2- (2′-hydroxy-3′-t-butyl 5′-methylphenyl-)-5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl-) -Benzotriazole, 2- (2'-hydroxy-5'-t-octyl phenyl) -benzotriazole, 2- (2'-hydroxy 3 ', 5'-di-t-amyl phenyl) -)-Benzotriazole and the like. Other compounds include 2,4, di-t-butylphenyl 3 ', 5'-di-t-butyl-4'-hydroxybenzoate, nickel dibutyl-dithiocarbamate and the like.

Further, at least one kind of electron accepting substance can be included for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, and the like. Examples of the electron-accepting substance that can be used for the photosensitive drum include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-di- Examples thereof include nitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, and phthalic acid. Of these, fluorenone-based, quinone-based, and benzene derivatives having electron-withdrawing substituents such as Cl, CN, NO ₂ are particularly preferable.

  The charge transport layer can also contain particles such as silica and fluorine-based resin. The content of the fluororesin in the charge transport layer is suitably from 0.1 to 40 wt%, particularly preferably from 1 to 30 wt%, based on the total amount of the charge transport layer. If the content is less than 1 wt%, the modification effect due to the dispersion of the fluororesin particles is not sufficient, while if it exceeds 40 wt%, the light transmission property is lowered and the residual potential is increased by repeated use.

  The fluororesin particles used here include ethylene tetrafluoride resin, ethylene trifluoride chloride resin, propylene hexafluoride resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin and their co-polymers. It is desirable to appropriately select one or two or more of the polymers, but particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin.

  A small amount of silicone oil can be added to the coating solution as a leveling agent for improving the smoothness of the coating film.

In addition, a high-strength surface layer can be provided in order to provide resistance to abrasion and scratches on the surface layer. As this high-strength surface layer, conductive particles are dispersed in a binder resin, lubricating particles such as fluororesin and acrylic resin are dispersed in a normal charge transport layer material, silicon, acrylic and other hard materials A coating agent can be used, but from the viewpoint of strength, electrical characteristics, image quality maintenance, etc., those having a charge transporting property and comprising a siloxane-based resin having a crosslinked structure are preferable. The structure represented by the formula (I) is preferable because of its strength and stability.
GDF: general formula (I)
Where G is an inorganic glassy network subgroup, D is a flexible organic subunit, and F is a charge transporting subunit.

  F in the general formula (I) has a structure having photocarrier transport properties, such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds. And quinone compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, ethylene compounds, and the like.

  G in the general formula (I), particularly preferably a reactive Si group, is for causing a cross-linking reaction with each other to form a three-dimensional Si—O—Si bond, ie, an inorganic glassy network. .

  D in the above general formula (I) is for binding F for imparting charge transportability to the three-dimensional inorganic glassy network by direct bonding. In addition, the inorganic glassy network, which has firmness but is brittle, is imparted with appropriate flexibility and has an effect of improving the strength as a film.

The group capable of binding to the compound represented by the general formula (I) means a group capable of binding to a silanol group generated when the compound represented by the general formula (I) is hydrolyzed. means _{-Si (R 1) (3-} a) group represented by _{Q a,} epoxy group, isocyanate group, carboxyl group, hydroxy group, halogen and the like. Of _{these, -Si (R 1) (3} -a) group represented by _{Q a,} epoxy group, compounds having isocyanate group is preferable because it has a stronger mechanical strength. Furthermore, those having two or more of these groups in the molecule are preferable because the crosslinked structure of the cured film becomes three-dimensional and has higher mechanical strength.

  For the purpose of adjusting the film formability and flexibility of the film, it may be used by mixing with other coupling agents and fluorine compounds. As such a compound, various silane coupling agents and commercially available silicon-based hard coat agents can be used.

As silane coupling agents, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxy Silane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, tetramethoxysilane, methyltrimethoxysilane, Dimethyldimethoxysilane and the like can be used. Commercially available hard coat agents include KP-85, X-40-9740, X-40-2239 (manufactured by Shin-Etsu Silicone), and AY42-440, AY42-441, AY49-208 (manufactured by Toray Dow Corning). Can be used. In addition, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, 3- (hepta) for imparting water repellency and the like. Fluoroisopropoxy) propyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorooctyl Fluorine-containing compounds such as triethoxysilane may be added. The silane coupling agent can be used in any amount, but the amount of the fluorine-containing compound is desirably 0.25 or less by weight with respect to the compound not containing fluorine. Beyond this, there may be a problem with the film formability of the crosslinked film. In order to improve the strength of the membrane, it is used _{-Si (R 1) (3-} a) Q a compound that a substituted silicon group having 2 or more having a hydrolyzable group represented simultaneously More preferred.

  These coating solutions are prepared without solvent or, if necessary, alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, diethyl ether and dioxane. Although it can be used, it preferably has a boiling point of 100 ° C. or less, and can be used by arbitrarily mixing. The amount of the solvent can be arbitrarily set, but if it is too small, the compound represented by the general formula (I) is likely to be precipitated, so 0.5 to 30 parts, preferably 1 part of the compound represented by the general formula (I) 1-20 parts. Although the reaction temperature and time vary depending on the type of raw material, it is usually 0 to 100 ° C., preferably 10 to 70 ° C., particularly preferably 150 to 50 ° C. Although there is no restriction | limiting in particular in reaction time, Since it will become easy to produce gelation when reaction time becomes long, it is preferable to carry out in 10 minutes to 100 hours.

  Further, examples of the curing catalyst include the following.

  Protic acids such as hydrochloric acid, acetic acid, phosphoric acid and sulfuric acid, bases such as ammonia and triethylamine, organotin compounds such as dibutyltin diacetate, dibutyltin dioctoate and stannous oxalate, tetra-n-butyl titanate, tetraisopropyl titanate Examples of organic titanium compounds such as aluminum tributoxide, aluminum triacetylacetonate, etc., iron salts of organic carboxylic acids, manganese salts, cobalt salts, zinc salts, zirconium salts, etc. A metal compound is preferable, and further, metal acetylacetonate or acetylacetate is preferable, and aluminum triacetylacetonate is particularly preferable. The amount of the curing catalyst used can be arbitrarily set, but is preferably 0.1 to 20 wt% with respect to the total amount of the material containing hydrolyzable silicon substituents in terms of storage stability, characteristics, strength, etc. 3-10 wt% is more preferable. The curing temperature can be arbitrarily set, but is set to 60 ° C. or higher, more preferably 80 ° C. or higher in order to obtain a desired strength. Although hardening time can be arbitrarily set as needed, 10 minutes-5 hours are preferable. It is also effective to stabilize the characteristics after the curing reaction by maintaining a high humidity state. Furthermore, depending on the application, it can be hydrophobized by surface treatment with hexamethyldisilazane, trimethylchlorosilane, or the like.

  It is preferable to add an antioxidant to the surface cross-linked cured film of the photosensitive drum for the purpose of preventing deterioration due to an oxidizing gas such as ozone generated by the charger. When the mechanical strength of the surface of the photoconductive drum is increased and the photoconductive drum has a long life, the photoconductive drum comes into contact with the oxidizing gas for a long time. Antioxidants are preferably hindered phenols or hindered amines, organic sulfur antioxidants, phosphite antioxidants, dithiocarbamate antioxidants, thiourea antioxidants, benzimidazole antioxidants. , Etc., may be used. The addition amount of the antioxidant is preferably 20% by weight or less, and more preferably 10% by weight or less.

  Examples of the hindered phenol antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,5-di-t-butylhydroquinone, N, N′-hexamethylene bis (3,5-di). -T-butyl-4-hydroxyhydrocinnamide, 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester, 2,4-bis [(octylthio) methyl] -o-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol) 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 2,5-di-t-amylhydroquinone, 2-t-butyl-6- (3-butyl-2- Dorokishi-5-methylbenzyl) -4-methylphenyl acrylate, 4,4'-butylidene bis (3-methyl -6-t-butylphenol), and the like.

  Also, a resin that dissolves in alcohol can be added for the purposes of discharge gas resistance, mechanical strength, scratch resistance, particle dispersibility, viscosity control, torque reduction, wear amount control, pot life extension, and the like. Examples of resins that are soluble in alcohol solvents include polyvinyl acetal resins such as polyvinyl butyral resin, polyvinyl formal resin, and partially acetalized polyvinyl acetal resin in which a part of butyral is modified with formal or acetoacetal (for example, manufactured by Sekisui Chemical Co., Ltd.) ESREC B, K, etc.), polyamide resin, cellulose resin, phenol resin and the like. In particular, polyvinyl acetal resin is preferable in terms of electrical characteristics. The molecular weight of the resin is preferably 2000-100000, more preferably 5000-50000. If the molecular weight is less than 2000, the desired effect cannot be obtained. If the molecular weight is more than 100,000, the solubility becomes low and the addition amount is limited, or the film formation is poor at the time of coating. The addition amount is preferably 1 to 40%, more preferably 1 to 30%, and most preferably 5 to 20%. When it is less than 1%, it is difficult to obtain a desired effect, and when it is more than 40%, image blurring under high temperature and high humidity tends to occur.

  Furthermore, various particles can be added in order to improve the contamination resistance adhesion and lubricity on the surface of the photosensitive drum. They can be used alone or in combination. An example of the particles may include silicon-containing particles. Silicon-containing particles are particles containing silicon as a constituent element, and specific examples include colloidal silica and silicone particles. The colloidal silica used as the silicon-containing particles is selected from those dispersed in an acidic or alkaline aqueous dispersion having an average particle diameter of 1 to 100 nm, preferably 10 to 30, or an organic solvent such as alcohol, ketone and ester. A commercially available product can be used. The solid content of colloidal silica in the outermost surface layer is not particularly limited, but is 0.1 to 50% by weight in the total solid content of the outermost surface layer in terms of film forming properties, electrical characteristics, and strength. Is used, preferably in the range of 0.1 to 30% by weight.

  Silicone particles used as silicon-containing particles are spherical and have an average particle diameter of 1 to 500 nm, preferably 10 to 100 nm, and are selected from silicone resin particles, silicone rubber particles, and silicone surface-treated silica particles, and are generally commercially available. Can be used. Silicone particles are small particles that are chemically inert and have excellent dispersibility in resins, and because the content required to obtain sufficient properties is low, photosensitivity can be achieved without inhibiting the crosslinking reaction. The surface property of the body drum can be improved. In other words, it is possible to improve the lubricity and water repellency of the surface of the photosensitive drum while being uniformly incorporated into a strong cross-linked structure, and to maintain good wear resistance and adherence to contaminants over a long period of time. . The content of the silicone particles in the outermost surface layer in the photosensitive drum is in the range of 0.1 to 30% by weight, preferably in the range of 0.5 to 10% by weight in the total solid content of the outermost surface layer. .

Other particles include fluorine-based particles such as ethylene tetrafluoride, ethylene trifluoride, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, and the 8th Polymer Materials Forum Lecture Proceedings p89. Particles made of a resin obtained by copolymerizing the fluororesin and a monomer having a hydroxyl group, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O ₃ —SnO ₂ , ZnO—TiO ₂ , Examples thereof include semiconductive metal oxides such as ZnO—TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , In ₂ O ₃ , ZnO, and MgO. For the same purpose, an oil such as silicone oil can be added. Examples of silicone oil include silicone oil such as dimethylpolysiloxane, diphenylpolysiloxane, and phenylmethylsiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, methacryl-modified polysiloxane, and mercapto. Reactive silicone oils such as modified polysiloxanes and phenol-modified polysiloxanes, cyclic dimethylcyclosiloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, 1,3, 5-trimethyl-1,3,5-triphenylcyclotrisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetraphenylsilane Cyclomethylphenylcyclosiloxanes such as rhotetrasiloxane, 1,3,5,7,9-pentamethyl-1,3,5,7,9-pentaphenylcyclopentasiloxane, and cyclic phenylcyclo such as hexaphenylcyclotrisiloxane Hydrosilyl group-containing cyclosiloxanes such as siloxanes, fluorine-containing cyclosiloxanes such as 3- (3,3,3-trifluoropropyl) methylcyclotrisiloxane, methylhydrosiloxane mixtures, pentamethylcyclopentasiloxane and phenylhydrocyclosiloxanes And cyclic siloxanes such as vinyl group-containing cyclosiloxanes such as pentavinylpentamethylcyclopentasiloxane.

  A siloxane-based resin having a charge transporting property and having a cross-linked structure has excellent mechanical strength and sufficient photoelectric characteristics. Therefore, it can be used as it is as a charge transport layer of a multilayer photoreceptor. In that case, a usual method such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method can be used. However, when a required film thickness cannot be obtained by a single application, the necessary film thickness can be obtained by applying a plurality of times. When performing multiple times of repeated application, the heat treatment may be performed every time of application, or after multiple times of repeated application.

  In the case of a single-layer type photosensitive layer, the photosensitive layer is formed containing the charge generating material and a binder resin. As the binder resin, the same binder resins as those used in the charge generation layer and the charge transport layer can be used. The content of the charge generating substance in the single-layer type photosensitive layer is about 10 to 85% by weight, preferably 20 to 50% by weight. A charge transport material or a polymer charge transport material may be added to the single-layer type photosensitive layer for the purpose of improving photoelectric characteristics. The addition amount is preferably 5 to 50% by weight. Moreover, you may add the compound shown by the said general formula (I). The solvent and coating method used for coating can be the same as described above. The film thickness is preferably about 5 to 50 μm, more preferably 10 to 40 μm.

  Furthermore, the surface layer of the photosensitive drum can be coated with an aqueous dispersion of a modified resin containing a fluororesin as an essential component, or can be dipped. This is preferable because the torque can be further reduced and the transfer efficiency can be improved.

  An aqueous dispersion of a modified resin containing a fluororesin as an essential component for treating the surface layer of the photosensitive drum will be described.

  Fluorocarbon resins include tetrafluoroethylene homopolymers or copolymers of tetrafluoroethylene and olefins, fluorine-containing olefins, perfluoroolefins, fluoroalkyl vinyl ethers, vinylidene fluoride homopolymers or vinylidene fluoride and olefins, fluorine-containing Copolymers with olefins, perfluoroolefins, fluoroalkyl vinyl ethers, homopolymers of chlorotrifluoroethylene or copolymers of chlorotrifluoroethylene with olefins, fluorine-containing olefins, perfluoroolefins, fluoroalkyl vinyl ethers, etc. , Tetrafluoroethylene homopolymers or copolymers are preferred, and tetrafluoroethylene homopolymers and various The polymer in a weight ratio of 95: 5 to 10: it is also preferable to use a mixture with 90.

  The modified resin containing a fluororesin as an essential component is used as an aqueous dispersion, and the aqueous dispersion may further contain a wax and / or silicone. By containing wax and / or silicone, it is preferable to promote penetration of the fluorine-based resin into the cleaning blade. Here, examples of the wax include paraffin wax, microcrystalline wax, and perotratam. Examples of the silicone include silicone oil, silicone grease, oil compound, and silicone varnish.

  For aqueous dispersions of modified resins containing fluorine resin as an essential component, fluorine-based or other nonionic, cationic, anionic or amphoteric surfactants, pH adjusters, solvents, polyhydric alcohols, flexible An agent, a viscosity modifier, a light stabilizer, an antioxidant and the like can also be mixed.

The permeation layer can be formed by immersing it in an aqueous dispersion of a modified resin containing a fluororesin as an essential component, but it can also be performed under reduced pressure to promote permeation of the fluororesin. it can. The pressure at this time is 0.9 atm or less, preferably 0.8 atm or less, more preferably 0.7 atm or less. In addition, heating the aqueous dispersion to 40 ° C. or higher, preferably 50 ° C. or higher is effective in promoting penetration. Further, it is effective to treat at 0.1 atm or higher, preferably 0.2 atm or higher, more preferably 0.3 atm or higher, and it is also effective to combine decompression, pressurization and heat treatment. is there. Moreover, after making it adhere by spraying or the apply | coating method, it can heat to 40 degreeC or more, Preferably it is 50 degreeC or more, and an osmosis | permeation layer can also be formed. After the aqueous dispersion of the modified resin containing a fluorine-based resin as an essential component is attached, it can be wiped off or washed before or after heat drying.
(Example)
Hereinafter, the embodiment of the present invention will be described in more detail using examples. The present invention is not limited to the following examples.

As an experimental machine, an image forming apparatus having the same configuration as that of the image forming apparatus shown in FIG. 1 was used except that the roll brush of the belt cleaner apparatus was replaced with a roll body (hereinafter referred to as a charge imparting roll body). Details are as follows.
Photosensitive drum Material: OPC sensitive material (84mm in diameter)
Process speed 160mm / sec
Primary transfer roll Urethane foam on a metal roll, the diameter is 12 mm, and the volume resistivity is 10 ¹³ Ω · cm.
Bias roll A foamed urethane rubber blended with an ionic conductor, has a diameter of 18 mm, and a low volumetric efficiency of 10 ⁸ Ω · cm.
Latent image potential -200V
Background potential -700V
Intermediate transfer belt drive system: belt driven by photosensitive drum drive
Base material: A blend of chloroprene rubber and EPDM (ethylene-propylene-diene rubber) Protective layer: Water-based paint Emuralon 345 (manufactured by Japan Atchison)
Volume resistance: 10 ⁹ Ω · cm
Belt cleaner device Charged roll body Roll body made of SUS with a diameter of 12 mm Applied bias Superposed with a DC voltage of 2.5 kv and an AC voltage with a peak-to-peak of 1.5 kv Cleaning roller A roller with a diameter of 10 mm having a urethane foam layer The hardness of the peripheral surface is 60 ° when measured with an Asker-FP hardness meter manufactured by Kobunshi Keiki Co., Ltd.

  Using the image forming apparatus configured as described above, four types of continuous output (continuous output of seven sheets, continuous output of 28 sheets, continuous output of 68 sheets of paper, and continuous output of 125 sheets of paper) ( Output of 14 cycles (output of 228 × 14 sheets) is performed with the output of 228 sheets in total) as one cycle output. As described above, the cleaning roller is controlled to come into contact with the photosensitive drum in accordance with the number of continuous outputs. The above-described continuous output of seven sheets, continuous output of 28 sheets, and continuous of 68 sheets of paper are performed. With respect to the four types of continuous output of the output and the continuous output of 125 sheets of paper, after each continuous output is completed, the contact with the photosensitive drum is performed for 3 seconds, 7 seconds, 12 seconds, and 15 seconds, respectively. Then, four types of contact according to the number of such continuous outputs are repeated 14 times. This is an example.

  Further, in the above embodiment, the cleaning roller and the photosensitive drum are in contact with each other for a fixed fixed time that is not related to the number of output sheets when continuous output is performed after the end of continuous output. A case where the above-described 14-cycle output is performed by an image forming apparatus that performs the same operation as the used image forming apparatus is a comparative example of the above-described embodiment. Here, a comparative example in which the 14 cycles of output are performed by the image forming apparatus in which the fixed fixed time is 3 seconds is referred to as Comparative Example 1, and similarly, an image in which the fixed fixed time is 7 seconds. A comparative example in which the output of the 14 cycles is performed by the forming apparatus is referred to as Comparative Example 2, and a comparative example in which the output of the 14 cycles is performed by the image forming apparatus in which the fixed fixed time is 12 seconds is compared. Example 3 is referred to as Comparative Example 4 in which the 14 cycles of output are performed by the image forming apparatus in which the fixed fixed time is 15 seconds.

  FIG. 4 is a diagram showing the examination result of the image quality defect of the formed image in Example and Comparative Examples 1 to 4.

  As shown in FIG. 4, in the example in which the contact time between the cleaning roller and the photosensitive drum is controlled according to the number of output sheets, white streaks were not observed in the formed image. In Comparative Examples 1 to 4 in which the cleaning roller and the photosensitive drum are in contact with each other for a certain period of time, white streaks are observed in the formed image. Such streaks often occur when external additive particles are accumulated on the surface of the intermediate transfer member or when the intermediate transfer member itself is worn, resulting in image quality defects such as the occurrence of streaks. Through this detection, it is recognized that the external additive particles are not sufficiently removed, and conversely, the intermediate transfer member is worn due to excessive removal of the external additive particles.

  As can be seen from FIG. 4, in the comparative example 1 in which the contact time is constant for 3 seconds regardless of the number of continuous outputs, white streaks are observed. On the other hand, in the embodiment in which contact is performed for 3 seconds only with continuous output of 7 sheets and the contact time becomes longer as the number of continuous outputs increases, no white streak occurs. From this, it can be considered that in Comparative Example 1, the removal of the external additive particles during the continuous output of 28 sheets of paper, the continuous output of 68 sheets of paper, and the continuous output of 125 sheets of paper is not sufficient.

  Similarly, when the comparative example 2 in which the contact time is constant for 7 seconds is compared with the example in which the contact time becomes longer as the number of continuous outputs increases, in the example, the same output time for 28 sheets of paper is 7 seconds. Is abutted. However, in a situation where the number of output sheets has increased from 28 sheets, such as continuous output of 68 sheets of paper and continuous output of 125 sheets of paper, control is performed such that the contact time becomes longer as the number of continuous outputs increases in the embodiment. In contrast, in Comparative Example 2, the contact time is uniformly 7 seconds, which is shorter than that in the example. The occurrence of white streaks in Comparative Example 2 is considered to be mainly caused by insufficient removal of external additive particles during the continuous output of 68 sheets of paper and the continuous output of 125 sheets of paper. It can be seen that control according to the number of continuous outputs is preferable.

  Comparing Comparative Example 3 in which the contact time is constant for 12 seconds with the example, in Example, contact is made for 12 seconds with continuous output of 68 sheets of paper. However, in a situation where the number of output sheets is less than 68 sheets, such as continuous output of 7 sheets and continuous output of 28 sheets, the contact time is controlled to decrease as the number of continuous outputs decreases in the embodiment. On the other hand, in the comparative example 3, the contact time is uniformly 12 seconds, and the contact is performed for a long time compared to the example. The occurrence of white streaks in Comparative Example 3 is considered to be mainly caused by the wear of the intermediate transfer member due to the contact time being too long for the continuous output of 7 sheets and the continuous output of 28 sheets. Comparison with Example 3 also shows that control according to the number of continuous outputs is preferable as in the example.

  Comparing Comparative Example 4 in which the contact time is constant for 15 seconds with the example, in the example, the contact is made only for the continuous output of 125 sheets of paper for 15 seconds, and the number of continuous outputs is less than 15 seconds. In Comparative Example 4, the contact time is too long in the continuous output of 7 sheets, the continuous output of 28 sheets, and the continuous output of 68 sheets. May be worn.

  From these results, the contact time between the cleaning roller and the photosensitive drum is controlled in accordance with the number of output sheets, so that the burden on the intermediate transfer member is reduced and the remaining on the surface of the intermediate transfer member is reduced. It is confirmed that the additive is sufficiently removed.

  In the above description, the contact time between the cleaning roller and the photosensitive drum is controlled according to the number of recording media used for image formation. However, the present invention can be applied to the cleaning roller according to the density of the image to be formed. The contact time between the toner and the photosensitive drum may be controlled. Moreover, it may replace with control of contact time, and the form which controls contact force may be sufficient.

1 is a diagram illustrating a schematic configuration of a full-color image forming apparatus corresponding to an embodiment of an image forming apparatus of the present invention. FIG. 2 is a view of a part of the cleaning device shown in FIG. 1 when viewed from one end side of a rotating shaft of a photosensitive drum. 2 is a flowchart showing an operation of the image forming apparatus shown in FIG. 1 when removing residual toner and residual external additive. In an Example and Comparative Examples 1-4, it is the figure showing the investigation result of the image quality defect of a formed image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Photosensitive drum 10b Surface 20 Intermediate transfer belt 31 Charger 32 Exposure device 33 Cleaning device 34 Static eliminator 40 Primary transfer roll 50 Developing rotary 60 Bias roll 80 Belt cleaner apparatus 81 Roll brush 82 Power supply 83 Cleaning roll 831 Foam layer 90 Control unit

Claims (1)

In an image forming apparatus comprising an image carrier, forming a toner image on the surface of the image carrier, and transferring and fixing the toner image on a recording medium, thereby forming an image composed of a fixed toner image on the recording medium ,
An intermediate transfer member that receives the transfer of the toner image from the image carrier and transfers the transferred toner image to a recording medium;
Cleaning means for removing residues remaining on the surface of the image carrier after the toner image is transferred to the intermediate transfer member;
A charge imparting means for imparting a charge of a predetermined polarity to the residue remaining on the intermediate transfer member;
A cleaning roll having a foam layer on the peripheral surface, the peripheral surface of which is in contact with the intermediate transfer body in a contact state according to the formation state of the toner image;
Bias applying means for applying a bias having the same polarity as the predetermined polarity to the residue having the charge of the predetermined polarity and transferring the residue from the intermediate transfer member to the surface of the image carrier. Image forming apparatus.

Images