JP2006267954A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor realizing high image quality and high speed and an image forming apparatus using the same, in the image forming apparatus which adopts a method for forming an electrostatic latent image of a multi-beam system and especially a method for simultaneously scanning at least 3 or at least 10 laser beams by using a surface emitting laser which can be easily arrayed as a light source. <P>SOLUTION: The image forming apparatus is provided with at least the electrophotographic photoreceptor, a charging means, an exposing means, a developing means and a transferring means. The exposing means has a surface emitting laser array as the light source and a plurality of light beams from the surface emitting laser array scan on the electrophotographic photoreceptor and the light attenuation curve of the electrophotographic photoreceptor satisfies following expression (1), (VH-VL)×0.10≤[(VH+VL)/2]-VM≤(VH-VL)×0.30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, and more specifically, an ultra-high resolution capable of a recording density of 1200 dots / inch or more that can meet the demand for higher image quality. The present invention relates to an electrophotographic photosensitive member and an image forming apparatus using the same.

  As an exposure means used in a laser beam printer or a digital copying machine, a laser beam corresponding to an image signal is reflected from a semiconductor laser to a rotating polygon mirror (hereinafter referred to as “polygon mirror”), and the electrophotographic photosensitive member ( Hereinafter, a method of forming an electrostatic latent image by irradiating the surface (sometimes simply referred to as “photoreceptor”) is mainly used.

  In the case of such exposure means using a laser beam, it is necessary to increase the scanning speed of the laser beam in order to achieve high definition (high image quality) and high speed of the output image with one laser beam. Become. However, the rotational speed of the polygon mirror is limited.

  So, as a means for solving this problem, a multi-beam method in which an electrophotographic photosensitive member is scanned at a time with a plurality of laser beams has been proposed and realized. This multi-beam method has the following advantages.

  First, in the case of an image forming apparatus using N laser beams, the scanning line density is set to N when the scanning speed of the laser beam and the printing speed are set equal to the case of using a single laser beam. The image can be recorded at a high resolution.

  Further, when the scanning speed of the laser beam and the density of the scanning line are set equal to the case where a single laser beam is used, the printing speed can be increased N times. Furthermore, if the print speed and the scanning density of the laser beam are set equal to those when a single laser beam is used, the scanning speed of the laser beam, that is, the rotation speed of the polygon mirror can be increased by 1 / N times. Since the mechanism for rotationally driving the polygon mirror can be simplified, coasting down is possible.

  A plurality of such laser beams (light beams) are deflected and simultaneously scanned on a scanning object such as a photosensitive member, and an image is formed by scanning a plurality of scanning lines in one main scanning. As an image forming apparatus configured as described above, a surface emitting laser (VCSEL: Vertical Cavity EmittiNg Laser) that can be easily arrayed is used as a light source, and the number of laser beams that are scanned simultaneously (the number of scanning lines that are simultaneously scanned by laser beams). There has also been proposed a configuration that achieves high image quality and high image formation speed by increasing the image quality (see, for example, Patent Document 1).

On the other hand, with respect to high image quality, not all are determined only by high resolution, but fine line reproducibility, low density reproducibility, and the like are also problems. In an image forming apparatus using a surface emitting laser, the reason is not clear, but these characteristics tend to be worse than those using a conventional laser beam.
JP-A-5-294005

The present invention has been made in view of the above-described circumstances in the prior art, and overcomes the above-described problems, and in particular, an image forming apparatus and an electrophotographic photosensitive member having high image quality, high speed, small size, and long life. Provide the body.
That is, an object of the present invention is to employ a method of forming a multi-beam type electrostatic latent image, particularly a method of using a surface emitting laser that can be easily arrayed as a light source and simultaneously scanning 3 to 10 or more laser beams. It is an object of the present invention to provide an electrophotographic photosensitive member capable of realizing high image quality and high speed, and an image forming apparatus using the same.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1> An image forming apparatus including at least an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit,
The exposure means has a surface emitting laser array as a light source, and is configured to scan the electrophotographic photosensitive member with a plurality of light beams from the surface emitting laser array. In this image forming apparatus, the light attenuation curve satisfies the relationship of the following formula (1).
(VH−VL) × 0.10 ≦ [(VH + VL) / 2] −VM ≦ (VH−VL) × 0.30 (1)

  In the above formula, VH represents a pre-exposure potential, VL represents a post-exposure potential, and VM represents a potential when an exposure light amount that is 1/2 of the exposure light amount required to reduce VH to VL is exposed.

<2> The image forming apparatus according to <1>, wherein the electrophotographic photoreceptor includes at least an undercoat layer and a photosensitive layer on a conductive substrate, and the undercoat layer contains metal oxide fine particles. .

<3> The image forming apparatus according to <1> or <2>, wherein the metal oxide fine particles are at least one selected from tin oxide, titanium oxide, and zinc oxide.

<4> The image forming apparatus according to any one of <1> to <3>, wherein the number average particle diameter of the metal oxide fine particles is in a range of 0.01 to 0.5 μm.

<5> The image forming apparatus according to any one of <1> to <4>, wherein the metal oxide fine particles are surface-treated with a silane coupling agent.

<6> An electrophotographic photosensitive member having at least an undercoat layer and a photosensitive layer formed on the undercoat layer on a conductive substrate, wherein the undercoat layer is one or more coupling agents. The electrophotographic photosensitive member comprises metal oxide fine particles coated with a phthalocyanine pigment, wherein the photosensitive layer contains a phthalocyanine pigment, and the light attenuation curve satisfies the relationship of the following formula (1).
(VH−VL) × 0.10 ≦ [(VH + VL) / 2] −VM ≦ (VH−VL) × 0.30 (1)

  In the above formula, VH represents a pre-exposure potential, VL represents a post-exposure potential, and VM represents a potential when an exposure light amount that is 1/2 of the exposure light amount required to reduce VH to VL is exposed.

  According to the present invention, an image employing a method of forming a multi-beam type electrostatic latent image, particularly a method of using a surface emitting laser that can be easily arrayed as a light source and simultaneously scanning 3 to 10 or more laser beams. In the forming apparatus, it is possible to provide an electrophotographic photosensitive member capable of realizing high image quality and high speed, and an image forming apparatus using the same.

Hereinafter, the present invention will be described in detail.
The image forming apparatus of the present invention is an image forming apparatus including at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, and a transferring unit, and the exposing unit has a surface emitting laser array as a light source. The electrophotographic photosensitive member is scanned with a plurality of light beams from the surface emitting laser array, and the light attenuation curve of the electrophotographic photosensitive member satisfies the relationship of the following formula (1). It is characterized by.
(VH−VL) × 0.10 ≦ [(VH + VL) / 2] −VM ≦ (VH−VL) × 0.30 (1)

  In the above formula, VH represents a pre-exposure potential, VL represents a post-exposure potential, and VM represents a potential when an exposure light amount that is 1/2 of the exposure light amount required to reduce VH to VL is exposed.

  The present inventors use a surface emitting laser (VCSEL: Vertical Cavity Emitti Ng Laser) array as an exposure unit of an image forming apparatus, and the number of laser beams (light beams) to be scanned simultaneously (scanned simultaneously by the laser beams). By increasing the number of scanning lines (10 or more), the image forming speed is increased, the recording density is increased and the resolution is increased, and at the same time, a specific light attenuation curve (hereinafter referred to as “PIDC”). In combination with an electrophotographic photosensitive member having a high resolution, fine line reproducibility, low density reproducibility, etc., and compatibility with resolution can be achieved. I found.

  Specifically, when a surface emitting laser array is used as an exposure light source, the image forming speed can be increased as described above, but the reason for the surface emitting laser is not clear, but the reproducibility of fine lines, etc. However, there was a problem that it was inferior compared with the case of using a conventional laser. On the other hand, the above problem could be solved by using a photoconductor having a light attenuation curve characteristic satisfying the relationship of the above formula (1).

  Although it is not clear for what reason the reproducibility of fine lines and the reproducibility of low density portions is improved when the electrophotographic photoreceptor of the present invention is used, in the case of a photoreceptor having PIDC characteristics as described later. This is considered to be because the potential becomes lower with respect to the exposure corresponding to the intermediate potential, so that the reproducibility of the fine line and the dot of the halftone portion is improved.

Hereinafter, an example of an image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an image forming apparatus 10 of the present invention. The image forming apparatus 10 includes a photoconductor drum 12 that is rotated in a direction indicated by an arrow A by a driving unit (not shown) at a predetermined rotation speed, and an outer peripheral surface of the photoconductor drum 12 is above the photoconductor drum 12 in the drawing. Is provided with a charging device (charging means) 14. As the photosensitive drum 12, an electrophotographic photosensitive member of the present invention described later is used.

  A light beam scanning device (exposure means) 16 is disposed above the charger 14. As will be described in detail later, the light beam scanning device 16 includes a surface emitting laser array as a light source, and modulates a plurality of laser beams (light beams) emitted therefrom according to an image to be formed, The beam is deflected in the main scanning direction, and the outer peripheral surface of the photosensitive drum 12 is scanned in parallel with the axis of the photosensitive drum 12. Thereby, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 12.

  On the right side of the photosensitive drum 12 in the drawing, a developing device (developing means) 18 is disposed. The developing device 18 includes a roller-shaped container that is rotatably arranged. Four containers are formed inside the container, and developing units 18Y, 18M, 18C, and 18K are provided in each container. Each of the developing devices 18Y, 18M, 18C, and 18K includes a developing roller 20, and stores toner of each color Y, M, C, and K therein. Further, on the opposite side of the developing device 18 with the photoconductor drum 12 interposed therebetween, a charge eliminating / cleaning function having a function of discharging the outer peripheral surface of the photoconductive drum 12 and a function of removing unnecessary toner remaining on the outer peripheral surface. A vessel 22 is arranged.

  The full color image is formed by the image forming apparatus 10 while the photosensitive drum 12 is rotated four times. That is, while the photosensitive drum 12 is rotated four times, the charger 14 continues to charge the outer peripheral surface of the photosensitive drum 12, the charge removal / cleaning device 22 continues to remove the outer peripheral surface, and the light beam scanning device 16 should be formed. Each time the photosensitive drum 12 rotates, the laser beam modulated according to any one of the Y, M, C, and K image data representing the image is scanned on the outer peripheral surface of the photosensitive drum 12. Repeatedly while switching the image data used for laser beam modulation. Further, the developing device 18 operates the developing unit corresponding to the outer peripheral surface in a state where any of the developing rollers 20 of the developing units 18Y, 18M, 18C, and 18K corresponds to the outer peripheral surface of the photosensitive drum 12. The photosensitive drum 12 is rotated once by developing the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 12 to a specific color and forming a toner image of the specific color on the outer peripheral surface of the photosensitive drum 12. Each time the process is repeated, the container is rotated so that the developing unit used for developing the electrostatic latent image is switched.

  Thus, every time the photosensitive drum 12 makes one rotation, Y, M, C, and K toner images are sequentially formed on the outer peripheral surface of the photosensitive drum 12 so as to overlap each other. When the drum 12 rotates four times, a full-color toner image is formed on the outer peripheral surface of the photosensitive drum 12.

  Further, an endless intermediate transfer belt 24 is disposed substantially below the photosensitive drum 12 in the drawing. The intermediate transfer belt 24 is wound around rollers 26, 28, and 30, and is disposed so that the outer peripheral surface is in contact with the outer peripheral surface of the photosensitive drum 12. The rollers 26, 28, and 30 are rotated by the driving force of a motor (not shown), and rotate the intermediate transfer belt 24 in the direction of arrow B in FIG.

  A transfer device (transfer means) 32 is disposed on the opposite side of the photosensitive drum 12 with the intermediate transfer belt 24 interposed therebetween, and the toner image formed on the outer peripheral surface of the photosensitive drum 12 is transferred by the transfer device 32 to the intermediate transfer. The image is transferred to the image forming surface of the belt 24. When the toner image formed on the outer peripheral surface of the photoconductive drum 12 is transferred to the intermediate transfer belt 24, the area of the outer peripheral surface of the photoconductive drum 12 that carries the transferred toner image is removed by static elimination / removal. It is cleaned by the cleaner 22.

  A tray 34 is disposed below the intermediate transfer belt 24 in the drawing, and a large number of sheets as recording media are accommodated in the tray 34 in a stacked state. A take-out roller 36 is disposed on the upper left side of the tray 34 in FIG. 1, and a roller pair 38 and a roller 40 are sequentially arranged on the downstream side in the take-out direction of the paper P by the take-out roller 36. The uppermost sheet P in the stacked state is taken out from the tray 34 when the take-out roller 36 is rotated, and is conveyed by the roller pair 38 and the roller 40.

  A transfer device (transfer means) 42 is disposed on the opposite side of the roller 30 with the intermediate transfer belt 24 in between. The paper P conveyed by the roller pair 38 and the roller 40 is sent between the intermediate transfer belt 24 and the transfer device 42, and the toner image formed on the image forming surface of the intermediate transfer belt 24 is transferred by the transfer device 42. . A fixing device 44 having a pair of fixing rollers is arranged downstream of the transfer device 42 in the conveyance direction of the paper P. The paper P on which the toner image is transferred is transferred to the paper P by the fixing device 44. After being fused and fixed, the sheet is discharged out of the image forming apparatus 10 and placed on a discharge tray (not shown).

  Next, the light beam scanning device 16 will be described with reference to FIG. The light beam scanning device 16 includes a surface emitting laser array 50 that emits m (m is at least 3) laser beams. In FIG. 2, only three laser beams are shown for simplification, but a surface emitting laser array 50 formed by arraying surface emitting lasers should be configured to emit several tens of laser beams. In addition, the arrangement of the surface emitting lasers (arrangement of the laser beams emitted from the surface emitting laser array 50) may be arranged two-dimensionally (for example, in a matrix) in addition to the arrangement in one row. Is possible.

The surface emitting laser array 50 used in the present invention is particularly effective when the number of beams is 5 or more, preferably 8 or more, more preferably 16 or more, and still more preferably. 32 or more.
Further, although the light emitting points of the surface emitting laser array 50 can be preferably used in an electrophotographic apparatus arranged two-dimensionally, the arrangement is preferably arranged in 4 rows or more × 4 rows or more, more preferably 6 It is more than row x 6 rows or more, more preferably more than 8 rows x 8 rows. As a result, higher image quality (higher resolution) and higher speed are achieved.

  A collimating lens 52 and a half mirror 54 are sequentially arranged on the laser beam emitting side of the surface emitting laser array 50. The laser beam emitted from the surface emitting laser array 50 is made into a substantially parallel light beam by the collimator lens 52 and then incident on the half mirror 54, and a part of the laser beam is separated and reflected by the half mirror 54.

  A lens 56 and a light amount sensor 58 are arranged in this order on the laser beam reflecting side of the half mirror 54, and a part of the laser beam separated and reflected from the main laser beam (laser beam used for exposure) by the half mirror 54 is The light passes through the lens 56 and enters the light quantity sensor 58, and the light quantity is detected by the light quantity sensor 58.

  In addition, the surface emitting laser does not emit a laser beam from the side opposite to the side from which the laser beam used for exposure is emitted (in the case of an edge emitting laser, it is emitted from both sides), so that the light quantity of the laser beam is detected and controlled. In this case, it is necessary to separate a part of the laser beam used for exposure as described above and use it for light quantity detection.

  An aperture 60, a cylinder lens 62 having power only in the sub-scanning direction, and a folding mirror 64 are arranged in this order on the main laser beam emission side of the half mirror 54. The main laser beam emitted from the half mirror 54 is emitted from the aperture 60. Then, the light is refracted by the cylinder lens 62 so as to form a long linear image in the main scanning direction in the vicinity of the reflection surface of the rotary polygon mirror 66, and reflected by the folding mirror 64 to the rotary polygon mirror 66 side. The aperture 60 is desirably disposed in the vicinity of the focal position of the collimating lens 52 in order to uniformly shape a plurality of laser beams.

  The rotary polygon mirror 66 is rotated in the direction of arrow C in FIG. 2 by receiving a driving force of a motor (not shown), and deflects and reflects the incident laser beam reflected by the folding mirror 64 along the main scanning direction. Fθ lenses 68 and 70 having power only in the main scanning direction are arranged on the laser beam emission side of the rotary polygon mirror 66, and the laser beam deflected and reflected by the rotary polygon mirror 66 is the outer periphery of the photosensitive drum 12. It is refracted by the Fθ lenses 68 and 70 so as to move on the surface at a substantially constant speed and so that the image forming position in the main scanning direction coincides with the outer peripheral surface of the photosensitive drum 12.

  Cylinder mirrors 72 and 74 having power only in the sub-scanning direction are sequentially arranged on the laser beam emission side of the Fθ lenses 68 and 70, and the laser beams transmitted through the Fθ lenses 68 and 70 are connected in the sub-scanning direction. The image position is reflected by the cylinder mirrors 72 and 74 so as to coincide with the outer peripheral surface of the photosensitive drum 12, and is irradiated on the outer peripheral surface of the photosensitive drum 12. The cylinder mirrors 72 and 74 also have a surface tilt correction function that conjugates the outer peripheral surfaces of the rotary polygon mirror 66 and the photosensitive drum 12 in the sub-scanning direction.

  Further, on the laser beam emission side of the cylinder mirror 72, a pickup mirror 76 is disposed at a position corresponding to an end on the scanning start side (SOS: Start Of Scan) in the scanning range of the laser beam. A beam position detection sensor 78 is disposed on the laser beam emission side. When the laser beam emitted from the surface emitting laser array 50 reflects the incident beam in a direction corresponding to the SOS, the reflecting surface of the rotary polygon mirror 66 reflects the laser beam. Then, it is reflected by the pickup mirror 76 and enters the beam position detection sensor 78 (see also the imaginary line in FIG. 2).

  The signal output from the beam position detection sensor 78 modulates the laser beam scanned on the outer peripheral surface of the photosensitive drum 12 as the rotary polygon mirror 66 rotates to form an electrostatic latent image each time. Used to synchronize the modulation start timing in main scanning.

  Further, in the light beam scanning device 16, the collimating lens 52, the cylinder lens 62, and the two cylinder mirrors 72 and 74 are arranged so as to be afocal in the sub-scanning direction. This is because, as described in Japanese Patent Application Laid-Open No. 2001-515423, a difference in scanning line curvature (BOW) of a plurality of laser beams and a variation in scanning line interval due to the plurality of laser beams are suppressed. .

  Next, referring to FIG. 3, in the control device of the image forming apparatus 10, a portion that controls the emission of the laser beam from the surface emitting laser array 50 of the light beam scanning device 16 (hereinafter, this portion is referred to as a control unit 80. Will be described. The control device includes a storage unit 82 for storing image data representing an image to be formed by the image forming apparatus 10, and the image forming apparatus 10 forms an image in the image data stored in the storage unit 82. Is input to the modulation signal generating means 84 of the control unit 80.

  Although not shown, a beam position detection sensor 78 is connected to the modulation signal generation means 84. The modulation signal generation unit 84 decomposes the image data input from the storage unit 82 into m pieces of image data respectively corresponding to any of the m laser beams emitted from the surface emitting laser array 50 and decomposes the image data. Based on the m pieces of image data, the timing at which each of the m laser beams emitted from the surface emitting laser array 50 is turned on and off is based on the SOS timing detected by the signal input from the beam position detection sensor 78. M modulation signals to be defined are generated and output to a laser driving circuit (LDD) 86.

  The LDD 86 is connected with drive amount control means 88 (details will be described later), and m laser beams emitted from the surface emitting laser array 50 are supplied in accordance with the modulation signal input from the modulation signal generation means 84. The surface emitting laser array 50 generates on the surface emitting laser array 50 by turning on and off at the timing, and generating m drive currents for changing the light amount of the laser beam at the time of on to the light amount corresponding to the drive amount setting signal input from the drive amount control means 88. To m surface emitting lasers.

  As a result, the surface emitting laser array 50 emits m laser beams that are turned on and off at a timing corresponding to the modulation signal, and whose light amount when turned on is a light amount corresponding to the drive amount setting signal. Each of the laser beams is scanned and exposed on the outer peripheral surface of the photosensitive drum 12, whereby an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 12. The electrostatic latent image is developed as a toner image by the developing device 18, the toner image is transferred to the paper P after being transferred by the transfer devices 32 and 42, and is fused and fixed to the paper P by the fixing device 44. An image is recorded in P.

Next, the electrophotographic photosensitive member of the present invention incorporated in the image forming apparatus having the above-described configuration will be described.
First, FIG. 4 shows a light attenuation curve (PIDC, light attenuation characteristic) of a photoreceptor including the electrophotographic photoreceptor of the present invention. As shown in FIG. 4A, in a normal photoconductor, linear attenuation in which the potential is attenuated by a certain amount from the pre-exposure potential VH to the post-exposure potential VL with respect to a change in exposure light amount is ideal. However, in the electrophotographic photosensitive member of the present invention, as shown in FIG. 4B, it has a characteristic (curve connecting Δ plots in the figure) that protrudes below the straight line PQ connecting VH and VL. Use a good one.

  That is, in the light attenuation curve (PIDC) of the photoconductor used in the image forming apparatus of the present invention, the potential VM when the light amount E that is 1/2 of the exposure light amount necessary to reduce VH to VL is exposed (FIG. (Potential at point R in FIG. 2) is an intermediate potential (VH−VL) / 2 of the straight line obtained by connecting VH and VL with a straight line (potential at point S in FIG. It is necessary to use a photoreceptor having low characteristics in the range of 10 to 30% of the difference between VH and VL.

Specifically, the SR length in FIG. 4 needs to be in the range of 10 to 30% of the length of P′Q, and PIDC is required to satisfy the relationship of the following formula (1). The
(VH−VL) × 0.10 ≦ [(VH + VL) / 2] −VM ≦ (VH−VL) × 0.30 (1)

  For example, in FIG. 4, VH is 700 V and VL is 300 V with respect to the normalized light amount on the horizontal axis that is normalized with the light amount that becomes VL being 1, but at this time, the potential attenuation is as shown in (A). When it changes linearly, VM (potential when the normalized light quantity is 0.5) is 500V. However, in the photoconductor of the present invention, PIDC is greatly convex downward as shown in (B). In this case, since the difference between VH and VL is 400V, a photoconductor having a characteristic that SR is 10% or more, that is, 40V or more (460V or less) is selected.

  In the present invention, it is seen that fine line reproducibility and low density reproducibility are improved by combining a photoreceptor having such a PIDC characteristic with an exposure apparatus having a surface emitting laser array as the exposure light source. It was issued.

When the potential corresponding to SR is less than 10% of the potential corresponding to P′Q, good fine line and halftone reproducibility cannot be obtained. On the other hand, if it exceeds 30%, the reproducibility of the gradation on the relatively high density side deteriorates.
The ratio of the SR potential to P′Q is preferably in the range of 10 to 30%, and more preferably in the range of 10 to 20%.

Hereinafter, the structure of the electrophotographic photosensitive member of the present invention having the above characteristics will be described in detail.
The photoconductor of the present invention is not particularly limited in material and configuration as long as it satisfies the PIDC characteristics. In order to adjust the PIDC, the material type of the undercoat layer, the charge generation material type, the mass ratio of the charge generation material and the binder-resin (hereinafter, the mass ratio of various materials to the binder-resin is referred to as “P / B ratio”). In some cases, the charge transport material type, the P / B ratio between the charge transport material and the resin, and the like, and can be adjusted individually or in combination with each layer.

  FIG. 5 is a schematic view showing a cross section of an example of the electrophotographic photoreceptor of the present invention. In FIG. 5, the undercoat layer 4 is provided on the conductive substrate 3. Furthermore, a charge generation layer 1 is provided thereon, and a charge transport layer 2 is provided thereon.

  In the electrophotographic photosensitive member of the present invention, examples of the conductive substrate 3 include metals such as aluminum, nickel, chromium, and stainless steel; aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, and the like. Examples thereof include a plastic film provided with a thin film such as ITO; or paper and plastic film coated with or impregnated with a conductivity-imparting agent.

  Although these electroconductive base materials 3 are used as things of appropriate shapes, such as drum shape, sheet | seat shape, and plate shape, it is not limited to these. Furthermore, when using a metal pipe base as necessary, even if the surface remains as a raw pipe, processing such as mirror surface cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing, coloring treatment, etc. in advance May be done. By roughening the surface of the substrate, it is possible to prevent grain-like density spots due to interference light in the photosensitive body that may occur when a coherent light source is used.

  In order to maintain high image quality, an undercoat layer 4 is provided as an intermediate layer on the surface of the conductive substrate 3. The undercoat layer 4 prevents the injection of charges from the conductive substrate 3 to the photosensitive layer when the photosensitive layer having a laminated structure is charged, and the photosensitive layer is integrated with the conductive substrate 3. An action as an adhesive layer for adhering and holding, or in some cases, an antireflection effect of light of the conductive substrate 3 can be added.

  As the undercoat layer 3, acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, chloride In addition to polymer resin compounds such as vinyl-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium chelate compound, titanium chelate compound, aluminum chelate compound, titanium Known materials such as an alkoxide compound, an organic titanium compound, and a silane coupling agent can be used.

  In addition, a charge transporting resin having a charge transporting group, a conductive resin such as polyaniline, or the like can be used. These compounds can be used alone or as a mixture or polycondensate of a plurality of compounds. Among these, resins that are insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferably used. Furthermore, zirconium chelate compounds and silane coupling agents are excellent in performance, such as low residual potential, little potential change due to environment, and little potential change due to repeated use.

  Examples of the silane coupling agent include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-glycidoxy. Propyltrimethoxysilane, 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.

  Among these, silane coupling agents that are particularly preferably used include vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-aminopropyltri Examples include silane coupling agents such as ethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

  Examples of the zirconium chelate compound include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate. , Zirconium naphthenate, 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 glycol, titanium lactate ammonium Examples thereof include salts, 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, and aluminum tris (ethyl acetoacetate).

The undercoat layer 4 can contain a conductive substance for improving the photoreceptor characteristics.
The conductive substance preferably contains metal oxide fine particles. The metal oxide fine particles used in the present invention preferably have a powder resistance of about 10 ² to 10 ¹¹ Ω · cm. The reason is that the undercoat layer 4 needs to obtain an appropriate resistance in order to acquire leak resistance. Among these, it is preferable to use at least one metal oxide fine particle selected from titanium oxide, zinc oxide and tin oxide having the above resistance values in terms of leakage resistance, fog suppression, and charge leakage suppression from the charge generation layer. . Of these, zinc oxide is preferably used.

The number average particle diameter of the metal oxide fine particles is preferably in the range of 0.01 to 0.5 μm. If the volume average particle size is less than 0.01 μm, it is difficult to form a conductive path and the resistance may be increased, and if it exceeds 0.5 μm, the image quality may be affected.
The average particle diameter can be obtained as the number average particle diameter from the particle diameter and number obtained from an image obtained by a transmission electron microscope (TEM).

  In the present invention, the metal oxide fine particles used for the undercoat layer 4 can be subjected to a surface treatment. By performing the surface treatment, resistance value control, dispersibility control, and improvement in photoreceptor characteristics can be achieved.

  As the surface treatment agent, known materials such as a zirconium chelate compound, a titanium chelate compound, an aluminum chelate compound, a titanium alkoxide compound, an organic titanium compound, and a silane coupling agent can be used. These compounds can be used alone or as a mixture or polycondensate of a plurality of compounds. Among them, the silane coupling agent is excellent in performance such as a low residual potential, a small potential change due to the environment, a small potential change due to repeated use, and excellent image quality characteristics.

  Examples of the silane coupling agent, the zirconium chelate compound, the titanium chelate compound, and the aluminum chelate compound include the same substances as those described above.

As the surface treatment method, any known method can be used, but a dry method or a wet method can be used.
When surface treatment is performed by a dry method, a silane coupling agent dissolved directly or in an organic solvent is added dropwise with dry air or nitrogen gas while stirring the metal oxide fine particles with a mixer having a large shearing force. It is uniformly processed by spraying. The addition or spraying is preferably performed at a temperature below the boiling point of the solvent. Spraying at a temperature equal to or higher than the boiling point of the solvent is not preferred because it causes the solvent to evaporate before being stirred uniformly, causing the silane coupling agent to locally accumulate and making uniform processing difficult. After addition or spraying, baking can be performed at 100 ° C. or higher. Baking can be carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained.

  As the wet method, the metal oxide fine particles are stirred in a solvent, dispersed using ultrasonic waves, a sand mill, an attritor, a ball mill, etc., added with a silane coupling agent solution and stirred or dispersed, and then the solvent is removed. Is processed uniformly. The solvent removal method is distilled off by distillation. The removal method by filtration is not preferred because unreacted silane coupling agent tends to flow out, and the amount of silane coupling agent for obtaining desired characteristics is difficult to corntrol. After removing the solvent, baking can be performed at 100 ° C. or higher. Baking can be carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained. In the wet method, as a method for removing the metal oxide fine particle-containing water, a method of removing with stirring and heating in a solvent used for surface treatment, or a method of removing by azeotropic distillation with a solvent can be used.

  The amount of the silane coupling agent relative to the metal oxide fine particles in the undercoat layer 4 can be any amount as long as desired electrophotographic characteristics can be obtained. Further, the ratio between the gold image oxide fine particles and the matrix resin used in the undercoat layer 4 can be arbitrarily set as long as the desired electrophotographic characteristics can be obtained.

  The ratio between the metal oxide fine particles and the binder resin in the undercoat layer 4 can be arbitrarily set within a range where desired electrophotographic photoreceptor characteristics can be obtained, but in the present invention, the PIDC characteristics are set as described above. From the viewpoint, the mass ratio of the metal oxide fine particles to the binder resin (metal oxide fine particles / binder resin, volume ratio) is preferably in the range of 30/70 to 50/50, and is preferably 35/65 to 45/55. It is more preferable to set the range.

  Various organic or inorganic fine powders can be mixed in the undercoat layer 4 for the purpose of improving light scattering properties. In particular, white pigments such as titanium oxide, zinc oxide, zinc sulfide, lead white, and lithopone, inorganic pigments as extender pigments such as alumina, calcium carbonate, and barium sulfate, Teflon (R) resin particles, and benzoguanamine resin particles In addition, styrene resin particles are effective.

  The added fine powder has a number average particle size in the range of 0.01 to 2 μm. The fine powder is added as necessary. When added, the fine powder has a mass ratio of 10 to 80% by mass, more preferably 30 to 70% by mass, based on the solid content of the undercoat layer 4. Add in range.

  Various additives can be used in the coating liquid for forming the undercoat layer in order to improve electrical characteristics, environmental stability, and image quality. Additives include quinone compounds such as chloranil, bromoanil, anthraquinone, tetracyanoquinodimethane compounds, fluorenone such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone Compounds such as 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazol and 2,5-bis (4-naphthyl) -1,3,4-oxadiazole Azole, oxadiazole compounds such as 2,5-bis (4-diethylaminophenyl) 1,3,4 oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5 ′ tetra-t-butyl It is also effective to include an electron transporting substance such as a diphenoquinone compound such as diphenoquinone, an electron transporting pigment such as a polycyclic condensation system and an azo group. Any known electron transporting substance or electron transporting pigment can be used.

  In the formation of the undercoat layer coating liquid, when the fine powder such as the conductive material or the light scattering material as described above is mixed, the fine powder is added to the solution in which the resin component is dissolved and the dispersion treatment is performed. As a method for dispersing the fine powder in the resin, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used.

  Further, as the coating method used when the undercoat layer 4 is provided, the blade coating method, the wire bar coating method, the spray coating method, the dip coating method, the bead coating method, the air knife coating method, the curtain coating method and the like are used. The method can be used.

The thickness of the undercoat layer 4 in the present invention is preferably in the range of 0.01 to 50 μm, more preferably in the range of 15 to 30 μm.
When the thickness of the undercoat layer 4 is less than 0.01 μm, sufficient leakage resistance cannot be obtained, and when it exceeds 50 μm, a residual potential tends to remain during long-term use, which tends to cause an image density abnormality. There are drawbacks.

Next, the charge generation layer 1 will be described.
The charge generation layer 1 is composed of a known charge generation material and a binder resin. The binder resin can be selected from a wide range of insulating resins, and the binder resin can be selected from a wide range of insulating resins. Poly-N-vinyl carbazole, polyvinyl anthracene, polyvinyl pyrene, It can also be selected from organic photoconductive polymers such as polysilanes.

  Preferred binder resins include polyvinyl butyral 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 resins such as resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin can be mentioned, but are not limited thereto. These binder resins can be used alone or in combination of two or more.

  Any known charge generating material can be used, but metal and metal-free phthalocyanine pigments are particularly preferred. Among them, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine having a specific crystal structure are preferable from the viewpoint of sensitivity. preferable.

  The blending ratio (P / B ratio) between the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10. In particular, in order to obtain the PIDC characteristics in the present invention, 4: It is preferable to set it as the range of 6-6: 4. Further, as a method for dispersing them, a normal method such as a ball mill dispersion method, an attritor dispersion method, a sand mill dispersion method, or the like can be used. However, in this case, the condition that the crystal form of the charge generation material is not changed by the dispersion. Is needed. Incidentally, it has been confirmed that the crystal form is not changed before dispersion in any of the dispersion methods implemented in the present invention. Further, at the time of this dispersion, it is effective that the volume average particle diameter is 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

  Solvents used for these dispersions include methanol, ethanol, N-propanol, N-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, N-butyl acetate, dioxane. Ordinary organic solvents such as tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene can be used alone or in admixture of two or more.

  The thickness of the charge generation layer used in the present invention is preferably in the range of 0.1 to 5 μm, and more preferably in the range of 0.2 to 2.0 μm. In addition, as a coating method used when the charge generation layer is provided, usual methods 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, and a curtain coating method are used. Can be used. In addition, pigments that have been surface-treated with a coupling agent or the like for the purpose of increasing the dispersion stability of the pigment, light sensitivity, or stabilizing the electrical properties may be used. It may be added to the solution.

  As the charge transport layer 2 in the photoreceptor of the present invention, a layer formed by a known technique can be used. Those charge transport layers 2 are formed containing a charge transport material and a binder resin, or are formed containing a polymer charge transport material.

  Examples of the charge transport material used in the present invention include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, and xanthones. Compounds, benzophenone compounds, cyanovinyl compounds, electron transport compounds such as ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazones And hole transporting compounds such as a series compound. These charge transport materials can be used alone or in combination of two or more, but are not limited thereto.

  Examples of the binder resin used for the charge transport layer 2 include acrylic resin, polyarylate, polyester resin, polycarbonate resin such as bisphenol A type or bisphenol Z type, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer. Examples thereof include insulating resins such as coalescence, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorine rubber, and organic photoconductive polymers such as polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene.

The charge transport layer 2 can be formed by applying and drying a solution in which the charge transport material and the binder resin are dissolved in an appropriate solvent.
Examples of the solvent used for forming the charge transport layer 2 include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol and N-butanol, acetone, cyclohexanone and 2-butanone. Such as ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, or mixed solvents thereof. Can be used.

  The blending ratio (T / B ratio) between the charge transport material and the binder resin is preferably 10: 1 to 1: 5. In particular, in order to obtain the PIDC characteristic in the present invention, the T / B ratio is preferably in the range of 35:65 to 45:55.

  In addition, the charge transport layer 2 is provided with lubricating particles so as to impart lubricity so that the surface layer is less likely to be worn or scratched, and to improve the cleaning property of the developer attached to the photoreceptor surface. It is preferable to contain (for example, fluorine resin particles such as silica particles, alumina particles or polytetrafluoroethylene (PTFE), silicone resin fine particles). These lubricating particles can be used in combination of two or more. In particular, fluorine resin particles are preferably used.

Examples of the fluorine resin particles include tetrafluoroethylene resin, trifluorinated ethylene resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodiethylene chloride resin, and copolymers thereof. Of these, it is desirable to appropriately select one or more of them, and particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin.
The primary particle size of the fluororesin fine particles is preferably in the range of 0.05 to 1 μm, more preferably in the range of 0.1 to 0.5 μm. When the primary particle size is less than 0.05 μm, aggregation during dispersion or after dispersion may easily proceed. On the other hand, if it exceeds 1 μm, an image quality defect may easily occur.

  The content of the fluororesin fine particles in the charge transport layer 2 is suitably in the range of 0.1 to 40% by mass, particularly preferably in the range of 1 to 30% by mass, based on the total amount of the charge transport layer. If the content is less than 0.1% by mass, the modification effect due to the dispersion of the fluororesin particles may not be sufficient. On the other hand, if the content exceeds 40% by mass, the light transmission property decreases and the residual potential due to repeated use. May increase.

The charge transport layer 2 can be formed by applying and drying a charge transport layer forming coating solution in which a charge transport material, a binder resin, and other materials are dissolved in an appropriate solvent.
Examples of the solvent used for forming the charge transport layer 32 include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, and n-butanol, acetone, cyclohexanone, and 2-butanone. Such as ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether, or mixed solvents thereof. Can be used.

Further, a slight amount of a leveling agent such as silicone oil for improving the smoothness of the coating film can be added to the coating solution for forming the charge transport layer.
As a method for dispersing the fluororesin fine particles in the charge transport layer in the present invention, a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a high-pressure homogenizer, an ultrasonic disperser, a colloid mill, a collision-type medialess disperser, A method such as a through-type medialess disperser can be used.

Examples of the dispersion of the coating liquid for forming the charge transport layer 2 include a method of dispersing the fluorine resin particles and the like in a solution of a binder resin, a charge transport material and the like dissolved in a solvent.
In the step of producing a coating liquid for forming the charge transport layer 2, it is preferable to control the temperature of the coating liquid in the range of 0 ° C to 50 ° C. As a method of controlling the temperature of the coating liquid in the coating liquid manufacturing process to 0 ° C. to 50 ° C., cool with water, cool with wind, cool with refrigerant, adjust the room temperature of the manufacturing process, warm with hot water, with hot air You can use methods such as warming, heating with a heater, creating a coating liquid manufacturing facility with a material that does not easily generate heat, creating a coating liquid manufacturing facility with a material that easily dissipates heat, or creating a coating liquid manufacturing facility with a material that easily stores heat. .

  It is also effective to add a small amount of a dispersion aid in order to improve the dispersion stability of the dispersion and to prevent aggregation during the formation of the coating film. Examples of the dispersion aid include fluorine-based surfactants, fluorine-based polymers, silicone-based polymers, and silicone oils. Further, after dispersing, stirring, and mixing the fluororesin and the dispersion aid in a small amount of a dispersion solvent in advance, the mixture is dissolved and mixed with a solution obtained by mixing and dissolving the charge transport material, the binder resin, and the dispersion solvent, and then the method is performed. It is also an effective means to disperse.

The coating methods used when the charge transport layer 2 is provided include dip coating, push-up coating, spray coating, roll coater coating, wire bar coating, gravure coater coating, bead coating, curtain coating, A blade coating method, an air knife coating method, or the like can be used.
The thickness of the charge transport layer 2 is preferably in the range of 5 to 50 μm, and more preferably in the range of 15 to 37 μm.

Further, in the electrophotographic photosensitive member of the present invention, an anti-oxidant and a light stabilizing agent are contained in the photosensitive layer for the purpose of preventing deterioration of the photosensitive member due to ozone, oxidizing gas, or light / heat generated in the electrophotographic apparatus. Additives such as agents and heat stabilizers can be added.
For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. Examples of light stabilizers include derivatives such as benzophenone, benzoazole, dithiocarbamate, and tetramethylpipen.

In the present invention, a protective layer may be further provided on the charge transport layer 2. The protective layer is used to prevent chemical change of the charge transport layer 2 during charging or to further improve the mechanical strength of the photosensitive layer in a photoreceptor having a laminated structure.
The protective layer includes a curable resin, a cured resin film containing a charge transporting compound, a film formed by containing a conductive material in a suitable binder resin, and the like. Any curable resin can be used as long as it is a public resin. Examples thereof include phenol resin, polyurethane resin, melamine resin, diallyl phthalate resin, and siloxane resin.

Next, the developer used in the present invention will be described. In the image forming apparatus of the present invention, a one-component developer composed only of toner and a two-component developer composed of toner and carrier can be used.
The toner is not particularly limited by the production method, and for example, a kneading pulverization method or a kneading pulverization method in which a binder resin, a colorant, a release agent, and a charge control agent are kneaded, pulverized, and classified as necessary. A method of changing the shape of particles obtained by mechanical impact force or thermal energy, emulsion polymerization of a binder resin polymerizable monomer, and the formed dispersion, colorant, release agent, necessary Depending on the type of emulsion, a dispersion liquid such as a charge control agent is mixed, agglomerated and heat-fused to obtain toner particles, an emulsion polymerization agglomeration method, a polymerizable monomer, a colorant, and a release agent for obtaining a binder resin. Suspension polymerization method in which a solution such as a charge control agent is suspended in an aqueous solvent for polymerization, if necessary, a binder resin and a colorant, a release agent, and if necessary, a solution such as a charge control agent in an aqueous solvent It can be obtained by, for example, a dissolution suspension method in which it is suspended and granulated.

  In addition, a known method such as a production method in which the toner particles obtained by the above method are used as a core, and agglomerated particles are further adhered and heat-fused to have a core-shell structure can be used. From the viewpoint, a suspension polymerization method, an emulsion polymerization aggregation method, and a dissolution suspension method produced with an aqueous solvent are preferable, and an emulsion polymerization aggregation method is particularly preferable.

  The toner particles are composed of a binder resin, a colorant, and a release agent if necessary, and if necessary, silica or a charge control agent may be used. The volume average particle size of the toner particles is preferably in the range of 2 to 12 μm, and more preferably in the range of 3 to 9 μm.

In addition, the toner particle shape index SF1 is obtained by taking a toner particle dispersed on a slide glass or an optical microscope image of the toner into a Luzex image analyzer (manufactured by Nireco) through a video camera, and measuring the maximum length of 50 or more toners. The projected area is obtained, calculated by the following formula (4), and the average value thereof is obtained.
SF1 = (ML ² / A) × (π / 4) × 100 (4)
In the above, ML represents the maximum length of toner particles, and A represents the projected area of toner particles. In the present invention, an image with high development, transferability, and high image quality can be obtained by using a shape factor SF1 in the range of 100 to 140.

  The toner is used as a color toner for electrophotography by mixing with a carrier, and as the carrier, iron powder, glass beads, ferrite powder, nickel powder or the like having a resin coating on the surface thereof is used. used. The mixing ratio with the carrier can be set as appropriate.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.
<Example 1>
(Preparation of electrophotographic photoreceptor)
Zinc oxide: (number average particle diameter: 70 nm, prototype product manufactured by Teika) 100 parts by mass with 500 parts by mass of toluene is mixed with stirring, and 1.5 parts by mass of a silane coupling agent (KBM306, manufactured by Shin-Etsu Chemical Co., Ltd.) is added. Stir for 2 hours. Thereafter, toluene was distilled off under reduced pressure, and baking was performed at 150 ° C. for 2 hours to obtain silane coupling agent surface-treated zinc oxide fine particles.

  60 parts by mass of the surface-treated zinc oxide, 15 parts by mass of a curing agent (blocked isocyanate, Sumijoule 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), and 15 parts by mass of butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.) Were mixed with 38 parts by mass of methyl ethyl ketone dissolved in 85 parts by mass of methyl ethyl ketone and 25 parts by mass of methyl ethyl ketone, and dispersed in a sand mill for 2 hours using a glass bead having a diameter of 1 mm to obtain a dispersion.

  To the obtained dispersion, 0.005 part by mass of dioctyltin dilaurate was added as a catalyst to obtain an undercoat layer coating solution. Using this coating solution, it is applied onto an aluminum substrate having a diameter of 85 mm, a length of 340 mm, and a wall thickness of 1 mm by dip coating, followed by drying and curing at 1700C for 40 minutes to obtain an undercoat layer having a thickness of 20 μm. It was.

  Next, chlorogallium phthalocyanine having strong diffraction peaks at Bragg angles (2θ ± 0.2 °) of 7.4 °, 16.6 °, 25.5 °, and 28.3 ° in the X-ray diffraction spectrum. 1 part by weight, 1 part by weight of polyvinyl butyral (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.) as a binder resin and 100 parts by weight of N-butyl acetate, and treated with a glass shaker for 1 hour And dispersed. The obtained coating solution was dip-coated on the undercoat layer and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.15 μm.

  Next, 1 part by mass of tetrafluoroethylene resin particles, 0.02 part by mass of the fluorine-based graft polymer, and 5 parts by mass of tetrahydrofuran are sufficiently stirred and mixed together with 2 parts by mass of toluene. Obtained. Next, 4 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine and a bisphenol Z-type polycarbonate resin as a charge transport material 6 parts by mass (viscosity average molecular weight: 40,000) were mixed and dissolved in 23 parts by mass of tetrahydrofuran and 10 parts by mass of toluene, and then the tetrafluoroethylene resin particle suspension was added and mixed with stirring.

Using a high-pressure homogenizer (trade name LA-33S, manufactured by Nanomizer Co., Ltd.) equipped with a through-type chamber with fine flow dew, the dispersion treatment with the pressure increased to 400 kgf / cm ² was repeated 6 times. , 6-di-t-butyl-4-methylphenol was mixed to obtain a coating solution for forming a charge transport layer. This coating solution was applied onto the charge generation layer and dried at 115 ° C. for 40 minutes to form a charge transport layer having a thickness of 32 μm. Thus, an electrophotographic photoreceptor 1 was obtained.

(Evaluation by image forming device)
A modified machine in which a surface emitting laser array for emitting 36 laser beams was mounted on DocuColor 1256GA manufactured by Fuji Xerox Co., Ltd. was prepared, and the electrophotographic photosensitive member 1 was loaded into the modified machine to obtain an image forming apparatus.

(1) Image Quality Evaluation Using the image forming apparatus, a chart including fine lines and gradation images was printed as the exposure intensity at which VL300V was obtained when VH was 700V, and the following evaluation was performed.
-Resolution-
The reproducibility of the thin line portion was evaluated by visual observation and judged according to the following criteria.
○: 1 dot width ON and 1 dot width OFF vertical line and horizontal line of 1200 dpi or more are reproduced.
X: Vertical line and horizontal line with 1 dot width ON and 1 dot width OFF of 1200 dpi or more are not reproduced.

-Fine line reproducibility-
○: All of the diagonal thin line patterns of 1200 dpi or more are reproduced.
X: Diagonal lines are not reproduced.

-Low concentration reproducibility-
○: Low density (highlight) is reproduced without problems.
X: The gradation on the low density side is not reproduced.
The results are summarized in Table 1.

(2) PIDC characteristics of electrophotographic photosensitive member Using a universal scanner with a laser exposure system, the photosensitive member was set so that VH was 700 V and VL was 300 V, and PIDC was obtained by changing the amount of exposure light. The results are shown in FIG.
Moreover, VM was calculated | required from this figure and the difference of (VH + VL) / 2 and VM was calculated | required as ratio of (VH-VL). The results are shown in Table 1.

<Example 2>
(Preparation of electrophotographic photoreceptor)
100 parts by mass of zinc oxide (number average particle size: 70 nm, manufactured by Teica, specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts by mass of tetrahydrofuran, and a silane coupling agent (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) 25 parts by mass was added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain a silane coupling agent surface-treated zinc oxide.

  60 parts by mass of zinc oxide subjected to the surface treatment, 0.3 part by mass of alizarin, 13.5 parts by mass of a curing agent (blocked isocyanate, Sumidur 3173, manufactured by Sumitomo Bayern Urethane Co., Ltd.), butyral resin (ESREC BM- (1; manufactured by Sekisui Chemical Co., Ltd.) 10 parts by mass and 57 parts by mass of a solution obtained by dissolving 72 parts by mass of methyl ethyl ketone and 18 parts by mass of N-hexane were dispersed in a sand mill for 2 hours using glass beads having a diameter of 1 mm. A dispersion was obtained.

  To the resulting dispersion, 0.005 parts by mass of dioctyltin dilaurate and 4.0 parts by mass of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone) were added as a catalyst to obtain an undercoat layer coating solution. . Using this coating solution, it was applied onto an aluminum substrate by a dip coating method, followed by drying and curing at 170 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 25 μm.

  Next, the Bragg angle (2θ ± 0.2 °) in the X-ray diffraction spectrum of hydroxygallium phthalocyanine having diffraction peaks at 7.3 °, 16.0 °, 24.9 °, and 28.0 ° is shown. 15 parts by mass is mixed with 10 parts by mass of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin and 300 parts by mass of N-butyl acetate. After dispersing for 5 hours, the obtained coating solution was dip-coated on the undercoat layer and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.15 μm.

  Next, 25 parts by mass of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine and 15 parts by mass of N, N′-bis (3,4-dimethylphenyl) biphenyl-4-amine Bisphenol Z polycarbonate resin (viscosity average molecular weight: 40,000) 60 parts by mass, and 2,6-di-tert-butyl-4-methylphenol 5 parts by mass, tetrohydrofuran 280 parts by mass And 120 parts by mass of toluene were sufficiently mixed and dissolved. Using this coating solution, the charge generation layer was applied by a dip coating method and dried in hot air at 135 ° C. for 40 minutes to form a charge transport layer having a thickness of 30 μm. Thus, an electrophotographic photoreceptor 2 was obtained.

(Evaluation by image forming device)
In the evaluation of Example 1, the evaluation was performed in the same manner except that the electrophotographic photosensitive member 2 was used as the photosensitive member.
The results are shown in Table 1.

<Example 3>
An electrophotographic photoreceptor 3 similar to that of Example 1 was obtained except that the thickness of the undercoat layer was 5 μm.
In the evaluation of Example 1, the evaluation was performed in the same manner except that the electrophotographic photosensitive member 3 was used as the photosensitive member.
The results are shown in Table 1.

<Example 4>
(Preparation of electrophotographic photoreceptor)
Zinc oxide: (number average particle size: 10 nm, prototype product manufactured by Teika) 100 parts by mass with 500 parts by mass of toluene, and mixed with 1.5 parts by mass of a silane coupling agent (KBM306, manufactured by Shin-Etsu Chemical Co., Ltd.) Stir for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 150 ° C. for 2 hours to obtain surface-treated zinc oxide fine particles having a silane coupling agent.

Using these zinc oxide fine particles, an electrophotographic photosensitive member 4 was obtained in the same manner as in Example 1. Further, in the evaluation of Example 1, the evaluation was performed in the same manner except that the electrophotographic photosensitive member 4 was used as the photosensitive member.
The results are shown in Table 1.

<Comparative Example 1>
(Preparation of electrophotographic photoreceptor)
100 parts by mass of zinc oxide (number average particle size 70 nm, prototype manufactured by Teika) and 500 parts by mass of toluene are mixed with stirring, and 1.5 parts by mass of a silane coupling agent (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) is added thereto. And stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure, and baking was performed at 150 ° C. for 2 hours to obtain silane coupling agent surface-treated zinc oxide fine particles.

  60 parts by mass of the zinc oxide subjected to the surface treatment, 15 parts by mass of a curing agent (blocked isocyanate, Sumijour 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.) and 15 parts by mass of butyral resin (ESREC BM-1, manufactured by Sekisui Chemical Co., Ltd.) A solution obtained by dissolving 38 parts by mass of methyl ethyl ketone in 85 parts by mass of methyl ethyl ketone and 25 parts by mass of methyl ethyl ketone was dispersed in a sand mill for 2 hours using a glass bead having a diameter of 1 mm to obtain a dispersion.

  To the obtained dispersion, 0.005 part by mass of dioctyltin dilaurate was added as a catalyst to obtain an undercoat layer coating solution. Using this coating solution, it is applied on an aluminum substrate having a diameter of 85 mm, a length of 340 mm, and a thickness of 1 mm by a dip coating method, followed by drying and curing at 160 ° C. for 100 minutes to obtain an undercoat layer having a thickness of 20 μm. It was.

  Next, 15 masses of hydroxygallium phthalocyanine having diffraction peaks at X-ray diffraction spectra of Bragg angles (2θ ± 0.2 °) of 7.3 °, 16.0 °, 24.9 °, and 28.0 °. Parts are mixed with 10 parts by weight of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Company) as binder resin and 300 parts by weight of N-butyl acetate, and 0.5 hours in a horizontal sand mill with glass beads. Distributed. Using the obtained coating solution, dip coating was performed on the undercoat layer, followed by heating and drying at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.15 μm.

  Next, 1 part by mass of tetrafluoroethylene resin particles and 0.02 parts by mass of the fluorine-based graft polymer are sufficiently stirred and mixed together with 5 parts by mass of tetrahydrofuran and 2 parts by mass of toluene to obtain a tetrafluoroethylene resin particle suspension. It was. Next, 4 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine as a charge transport material, and bisphenol Z 6 parts by weight of a polycarbonate resin (viscosity average molecular weight: 40,000) and 23 parts by weight of tetrahydrofuran are mixed and dissolved in 10 parts by weight of toluene, and then the tetrafluoroethylene resin particle suspension is added thereto. Stir and mix.

Using the high-pressure homogenizer (trade name LA-33S, manufactured by Nanomizer Co., Ltd.) equipped with a through-type chamber having fine flow dew, the above mixed liquid was subjected to dispersion treatment by increasing the pressure to 400 kgf / cm ² six times. Further, 0.2 parts by mass of 2,6-di-t-butyl-4-methylphenol was mixed to obtain a coating solution for forming a charge transport layer. Using this coating solution, it was applied onto the charge generation layer and dried at 115 ° C. for 40 minutes to form a charge transport layer having a thickness of 32 μm. Thus, an electrophotographic photosensitive member 5 was obtained.

(Evaluation by image forming device)
In the evaluation of Example 1, the evaluation was performed in the same manner except that the electrophotographic photosensitive member 5 was used as the photosensitive member.
The results are shown in Table 1.

<Comparative example 2>
(Preparation of electrophotographic photoreceptor)
To 170 parts by mass of N-butyl alcohol in which 4 parts by mass of polyvinyl butyral resin (S-REC BM-S, manufactured by Sekisui Chemical Co., Ltd.) was dissolved, 30 parts by mass of an organic zirconium compound (acetylacetone zirconium butyrate) and an organic silane compound (γ-amino) 3 parts by mass of propyltrimethoxysilane) was added and mixed and stirred to obtain a coating solution for forming an undercoat layer.

  This coating solution is dip-coated on an aluminum substrate having a diameter of 84 mm roughened by a honing treatment, air-dried at room temperature for 5 minutes, heated to 50 ° C. for 10 minutes, 50 ° C., It was placed in a constant temperature and humidity chamber of 85% RH (dew point 47 ° C.), and a humidification hardening acceleration treatment was performed for 20 minutes. Then, it put into the hot air dryer and dried for 10 minutes at 170 degreeC, and formed the undercoat layer with a film thickness of 1 micrometer.

  Next, 1 of chlorogallium phthalocyanine having strong diffraction peaks at Bragg angles (2θ ± 0.2 °) in the X-ray diffraction spectrum of 7.4 °, 16.6 °, 25.5 °, and 28.3 °. Part by mass was mixed with 1 part by mass of polyvinyl butyral (Esreck BM-S, manufactured by Sekisui Chemical Co., Ltd.) and 100 parts by mass of N-butyl acetate, and the mixture was treated with a glass bead for 1 hour and dispersed. Using the obtained coating solution, dip coating was performed on the undercoat layer, followed by heating and drying at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.15 μm.

  Next, as a charge transport material, N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (45 parts by mass) and binding As a resin, 55 parts by mass of bisphenol Z polycarbonate resin (viscosity average molecular weight: 20,000) was dissolved by adding 280 parts by mass of tetorohydrofuran and 120 parts by mass of toluene. By applying this solution onto the charge generation layer using a dip coating apparatus, a drying process is performed at 135 ° C. for 40 minutes to form a charge transport layer having a layer thickness of 32 μm, and an electrophotographic film composed of three layers. Photoconductor 6 was produced.

(Evaluation by image forming device)
In the evaluation of Example 1, the evaluation was performed in the same manner except that the electrophotographic photosensitive member 6 was used as the photosensitive member.
The results are shown in Table 1.

<Comparative Example 3>
(Preparation of electrophotographic photoreceptor)
An undercoat layer and a charge generation layer were formed in the same manner as in the production of the electrophotographic photoreceptor of Example 2. Next, 15 parts by mass of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine and 15 parts by mass of N, N′-bis (3,4-dimethylphenyl) biphenyl-4-amine Bisphenol Z polycarbonate resin (viscosity average molecular weight: 40,000) 70 parts by mass, and 2,6-di-tert-butyl-4-methylphenol 5 parts by mass, tetrohydrofuran 280 parts by mass And 120 parts by mass of toluene were sufficiently mixed and dissolved. Using this coating solution, the charge generation layer was applied by a dip coating method and dried in hot air at 135 ° C. for 40 minutes to form a charge transport layer having a thickness of 30 μm. Thus, an electrophotographic photoreceptor 7 was obtained.

(Evaluation by image forming device)
In the evaluation of Example 1, the evaluation was performed in the same manner except that the electrophotographic photosensitive member 7 was used as the photosensitive member.
The results are shown in Table 1.

  As shown in Table 1, in Examples 1 to 4 using the photoconductor of the present invention, even when a surface emitting laser array is used as a light source, in addition to good resolution, fine line reproducibility and low density reproducibility are achieved. There were no major problems. On the other hand, in the comparative example using the photosensitive member that does not have a convex shape as defined in the present invention in PIDC characteristics, sufficient reproducibility of fine lines and halftones was not obtained.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention. It is a perspective view which shows schematic structure of a light beam scanning apparatus. It is a block diagram which shows schematic structure of a control part. It is explanatory drawing of the PIDC characteristic of an electrophotographic photoreceptor. 1 is a cross-sectional view illustrating an example of a configuration of an electrophotographic photosensitive member of the present invention. It is a figure which shows each PIDC characteristic of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charge generation layer 2 Charge transport layer 3 Conductive base material 4 Undercoat layer 10 Image forming apparatus 12 Photosensitive drum (electrophotographic photosensitive member)
14 Charger (Charging means)
16 Light beam scanning device (exposure means)
18 Developing device (developing means)
42 Transfer device (transfer means)
44 Fixing device 50 Surface emitting laser array 58 Light quantity sensor 66 Rotating polygon mirror 84 Modulation signal generation means 88 Drive amount control means 92 Level change means 94 Light quantity difference setting means 96 Print pattern 100 Prism pair

Claims (3)

An image forming apparatus comprising at least an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit,
The exposure means has a surface emitting laser array as a light source, and is configured to scan the electrophotographic photosensitive member with a plurality of light beams from the surface emitting laser array. An image forming apparatus characterized in that a light attenuation curve satisfies a relationship of the following formula (1).
(VH−VL) × 0.10 ≦ [(VH + VL) / 2] −VM ≦ (VH−VL) × 0.30 (1)
(In the above formula, VH represents a pre-exposure potential, VL represents a post-exposure potential, and VM represents a potential when an exposure light amount that is 1/2 of the exposure light amount necessary to reduce VH to VL is exposed.)   2. The image forming apparatus according to claim 1, wherein the electrophotographic photoreceptor comprises at least an undercoat layer and a photosensitive layer on a conductive substrate, and the undercoat layer contains metal oxide fine particles. . An electrophotographic photoreceptor having at least an undercoat layer and a photosensitive layer formed on the undercoat layer on a conductive substrate, wherein the undercoat layer is coated with one or more coupling agents. An electrophotographic photoreceptor comprising metal oxide fine particles, wherein the photosensitive layer contains a phthalocyanine pigment, and a light attenuation curve satisfies a relationship of the following formula (1).
(VH−VL) × 0.10 ≦ [(VH + VL) / 2] −VM ≦ (VH−VL) × 0.30 (1)
(In the above formula, VH represents a pre-exposure potential, VL represents a post-exposure potential, and VM represents a potential when an exposure light amount that is 1/2 of the exposure light amount necessary to reduce VH to VL is exposed.)

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