JP2012013749A - Organic photoreceptor, image forming device, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic photoreceptor that excels in a charging property, reduces a loss of the charging property even if repetitively used, prevents generation of a crack in a drying process upon manufacturing the photoreceptor, and improves gas-proof property against an active gas, and a process cartridge and an image forming device using the organic photoreceptor.SOLUTION: An organic photoreceptor including a conductive substrate on which an intermediate layer, an electric charge generating layer, and an electric charge transporting layer are sequentially laminated is characterized in that the electric charge transporting layer contains a cyclic olefin resin and a hindered phenol compound.

Description

  The present invention relates to an organic photoreceptor used in a copying machine, a printer, and the like, and an image forming apparatus and a process cartridge using the organic photoreceptor.

  In recent years, the use of electrophotographic copying machines and printers has increased in the field of printing and color printing, and the tendency to demand high-speed, clear characters and image information has also increased. As a light source in the field typified by an electrophotographic photosensitive member, a semiconductor laser that emits light with a wavelength of 380 to 800 nm is mainly used, and an organic photosensitive member sensitive to that region is often used. In addition to the demand for higher speed and higher image quality, the demand for cost reduction and miniaturization is increasing year by year. It is presumed that the demand for chargeability and wear resistance will be severer as the cost goes down and the size is reduced, and the long life and durability are improved.

  However, conventional conventional photoconductors are prone to film thickness wear due to repeated use. If the photoconductive layer thickness wears down, the photoconductor's chargeability and sensitivity deteriorate, background stain increases, and image density decreases. Deterioration of image quality such as the above occurred, and the abrasion resistance of the photoreceptor has been cited as a big problem.

  In response to the above-described problem of wear resistance, for example, it has been reported that a colloidal silica-containing curable siloxane resin is used as a surface layer of a photoreceptor (see, for example, Patent Document 1). The colloidal silica-containing curable siloxane resin is highly hygroscopic both in the siloxane bond (Si-O-Si bond) curable resin and colloidal silica. For example, the electrical resistance of the surface layer is reduced in a high temperature and high humidity environment. It is easy to cause image blur and image flow.

  Moreover, as a curable resin applied to the protective layer, a protective layer of a curable resin obtained by photopolymerization using a compound having an acryloyl group has been proposed (for example, see Patent Document 2). The protective layer also contains a filler such as a metal oxide in the curable resin, but the bond between the filler and the curable resin is weak, the strength as the protective layer is insufficient, and image blurring is also caused. However, it has not been able to solve the problem of image flow.

  On the other hand, even if the wear resistance is improved by applying the protective layer to the organic photoreceptor, there remains a problem in stabilizing the chargeability of the photoreceptor. It has been reported that an olefin resin is used as a binder resin for a charge transport layer for stabilizing the charging property (see Patent Document 3). Olefin resin has low dielectric constant and high charging ability (speed of response to charging) compared to polycarbonate and polyester used in conventional photoconductors, but at the time of photoconductor production. During the drying process, the compatibility with the charge transport material is lowered and cracks are likely to occur. In Patent Document 3, these problems are improved by using a specific charge transporting compound. However, the charge transporting compound is limited, and it is sufficient for the development of an organic photoreceptor requiring further improvement in characteristics. Is not a good solution.

Japanese Patent Laid-Open No. 6-118681 JP 2001-125297 A JP 2008-176290 A

  The object of the present invention is excellent in charging ability, little decrease in chargeability even after repeated use, and prevents the generation of cracks in the drying process during the production of the photoreceptor, thereby improving the gas resistance property against the active gas. It is to provide an organic photoreceptor. Another object of the present invention is to provide a process cartridge and an image forming apparatus using the organic photoreceptor.

  As a result of identifying the problems of the prior art, the present inventors have found that when an olefin resin having a cyclic structure is used as the binder resin of the charge transport layer in the layer structure of the organic photoreceptor, a hindered group having a polar group is used. When a phenolic antioxidant is used in combination, the compatibility between the olefin resin and the charge transporting compound can be improved, the crack resistance during the production of the photoreceptor is improved, the charging characteristics are improved, and a high charging potential can be imparted. It was found that the potential stability during repeated use was improved, and the present invention was achieved.

  The present invention is achieved by having the following configuration.

  1. An organic photoreceptor in which an intermediate layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive support, wherein the charge transport layer contains a cyclic olefin resin and a hindered phenol compound. Photoconductor.

  2. 2. The organic photoreceptor as described in 1 above, wherein the cyclic olefin resin is a resin having a repeating unit of the following general formula (1) or general formula (2).

(In the general formula (1), R ₁₁ and R ₁₂ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted carbonyl group. R ₁₁ and R ₁₂ may be bonded to each other to form a ring, n represents an integer of 20 to 5000, and * is a junction of repeating units.)

(In General Formula (2), R ₁ represents a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, or an alkoxy group, R ₂ represents hydrogen or —COOR ₂ , and R ₂ represents an alkyl group or a silyl group. Represents an integer of 20 to 5000, and * is a junction of repeating units.)
3. 3. The organophotoreceptor according to 1 or 2 above, wherein the organophotoreceptor has a protective layer on the charge transport layer and contains metal oxide particles in the protective layer.

  4). 4. The organophotoreceptor according to 3 above, wherein the protective layer is a protective layer formed by a polymerization reaction between metal oxide particles surface-treated with a polymerizable compound and the polymerizable compound.

  5. 5. The organic photoreceptor according to any one of 1 to 4, wherein the organic photoreceptor is an image forming apparatus that has at least a charging unit, an exposure unit, and a developing unit around the organic photoreceptor, and repeatedly forms an image. An image forming apparatus.

  6). 5. A process cartridge used in the image forming apparatus described in 5 above integrally includes at least one of the organic photoreceptor described in any one of 1 to 4 and a charging unit, an image exposing unit, and a developing unit. And a process cartridge configured to be removable from and into the image forming apparatus.

  By using the organic photoreceptor of the present invention, the charging characteristics, potential stability, gas resistance (active gas resistance), crack resistance during the production of the photoreceptor, etc. are improved, including the improvement of wear resistance characteristics. The improvement of the resistance to the use environment is noticeable.

1 is a schematic view in which functions of an image forming apparatus of the present invention are incorporated. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention. 1 is a cross-sectional view of a color image forming apparatus using an organic photoreceptor of the present invention.

  The organic photoreceptor of the present invention is an organic photoreceptor in which an intermediate layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive support, and the charge transport layer comprises a cyclic olefin resin and a hindered phenol compound. It is characterized by containing.

  The organic photoreceptor of the present invention has the above-described structure, so that the effects of the present invention can be remarkably achieved.

  First, the cyclic olefin resin used in the present invention will be described. The cyclic olefin resin refers to a polymer of a cyclic hydrocarbon compound having one or more C═C (double bond between carbons).

  The cyclic olefin resin according to the present invention may be a copolymer of a cyclic olefin and another monomer.

  Examples of the cyclic olefin resin include compounds represented by the following general formula (1) or general formula (2). These compounds are obtained by radical polymerization or ring-opening metacis polymerization using a cyclic olefin. be able to.

  Since the cyclic olefin resin has a high ratio of σ bonds in its resin structure, the dielectric constant is small, and the dielectric loss is also smaller than that of polycarbonate or the like. Characteristics with excellent potential stability can be obtained.

  As cyclic olefin resin of this invention, resin which has a repeating unit of the said General formula (1) or General formula (2) is preferable. In the present invention, these cyclic olefin resins are used as a binder resin for the charge transport layer.

  Hereinafter, the specific example of the repeating unit which the cyclic olefin resin of General formula (1) has is given.

  Next, the specific example of the repeating unit which the cyclic olefin resin of General formula (2) has is given.

  In the said General formula (1) and General formula (2), n of a repeating unit represents the integer between 20-5000, However, The integer between 40-3000 is more preferable. In the present invention, n is a value calculated from the number average molecular weight.

  Some of the exemplified compounds of the general formula (1) and the general formula (2) are manufactured and marketed by JSR Corporation, Nippon Zeon Corporation, and the like.

  Among the above exemplified compounds, the cyclic olefin resin having a carboxylic acid ester or an alkoxy group as a substituent has a strong interaction with the hindered phenol compound, and the charge transport layer using such a cyclic olefin resin increases the uniformity. In addition, the crack resistance is improved.

  The charge transport layer according to the present invention contains a hindered phenol compound together with the cyclic olefin resin. The hindered phenolic compound improves the compatibility between the cyclic olefin resin and the electron transporting compound, and as a result, can take advantage of the characteristics of the cyclic olefin resin having a low dielectric constant to provide a high charging potential and has a potential stability. It is possible to obtain a photoconductor which is good and has improved active gas resistance, crack resistance and the like.

  Here, the hindered phenol refers to compounds having a branched alkyl group at the ortho position relative to the hydroxyl group of the phenol compound and derivatives thereof (however, the hydroxyl group may be converted to alkoxy).

  Examples of typical hindered phenol compounds are given below.

  In the organic photoreceptor of the present invention, it is preferable to provide a protective layer containing metal oxide particles on the charge transport layer.

  In particular, a protective layer formed by a polymerization reaction between the metal oxide particles surface-treated with the polymerizable compound and the polymerizable compound is preferable. That is, in the course of the polymerization reaction that proceeds by chain polymerization of the polymerizable compound, the polymerizable compound that surface-treats the metal oxide particles also participates in the reaction progress of the chain polymerization, and as a result, the metal oxide particles are A protective layer formed by being incorporated into a resin produced by a polymerization reaction via a surface treatment agent is preferred.

  The metal oxide particles surface-treated with the polymerizable compound are preferably metal oxide particles such as silica, titanium oxide, alumina, zinc oxide, and tin oxide having a number average primary particle size of about 1 to 100 nm. By performing a surface treatment with a silane coupling agent having an unsaturated group, metal oxide particles surface-treated with a polymerizable compound can be obtained.

  Examples of the chain polymerizable compound having a surface treatment group include a compound represented by the following general formula (3).

(Wherein R ³ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aralkyl group having 1 to 10 carbon atoms, R ⁴ is an organic group having a polymerizable double bond, X is a halogen atom, an alkoxy group, an acyloxy group) A group, an aminoxy group, and a phenoxy group, and n is an integer of 1 to 3.)
By reacting these silane compounds and metal oxide particles, metal oxide particles surface-treated with a polymerizable compound can be produced.

  The protective layer formed by polymerizing the metal oxide particles surface-treated with the chain polymerizable compound as described above and the polymerizable compound has a thickness of 0.5 to 3.0 μm on the charge transport layer of the cyclic olefin resin. Even when installed as a thin protective layer, the wear resistance and scratch resistance are remarkably improved.

  The compound example of General formula (3) is given below.

_{S-1 CH 2 = CHSi (} CH 3) (OCH 3) 2
_{S-2 CH 2 = CHSi (} OCH 3) 3
S-3 CH ₂ = CHSiCl _{3
S-4 CH 2 = CHCOO (} CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5 CH 2 = CHCOO (} CH 2) 2 Si (OCH 3) 3
_{S-6 CH 2 = CHCOO (} CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-7 CH 2 = CHCOO (} CH 2) 3 Si (OCH 3) 3
_{S-8 CH 2 = CHCOO (} CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-9 CH 2 = CHCOO (} CH 2) 2 SiCl 3
_{S-10 CH 2 = CHCOO (} CH 2) 3 Si (CH 3) Cl 2
S-11 CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12 CH 2 = C (} CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13 CH 2 = C (} CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14 CH 2 = C (} CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15 CH 2 = C (} CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16 CH 2 = C (} CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17 CH 2 = C (} CH 3) COO (CH 2) 2 SiCl 3
_{S-18 CH 2 = C (} CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19 CH 2 = C (} CH 3) COO (CH 2) 3 SiCl 3
_{S-20 CH 2 = CHSi (} C 2 H 5) (OCH 3) 2
S-21 CH ₂ ═C (CH ₃ ) Si (OCH ₃ ) _{3
S-22 CH 2 = C (} CH 3) Si (OC 2 H 5) 3
_{S-23 CH 2 = CHSi (} OCH 3) 3
_{S-24 CH 2 = C (} CH 3) Si (CH 3) (OCH 3) 2
_{S-25 CH 2 = CHSi (} CH 3) Cl 2
_{S-26 CH 2 = CHCOOSi (} OCH 3) 3
_{S-27 CH 2 = CHCOOSi (} OC 2 H 5) 3
_{S-28 CH 2 = C (} CH 3) COOSi (OCH 3) 3
_{S-29 CH 2 = C (} CH 3) COOSi (OC 2 H 5) 3
_{S-30 CH 2 = C (} CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
On the other hand, the following compounds are preferably used as the polymerizable compound.

  Examples of the polymerizable compound are shown below. The number of Ac groups (the number of acryloyl groups) or the number of Mc groups (the number of methacryloyl groups) described below represents the number of acryloyl groups or methacryloyl groups.

  However, in the above, R is shown below.

  However, in the above, R 'is shown below.

  When the polymerizable compound according to the present invention is reacted, a method of reacting by electron beam cleavage, a method of reacting with light or heat by adding a radical polymerization initiator or a cationic polymerizable initiator, and the like are used. As the polymerization initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used. Further, both light and heat initiators can be used in combination.

As a radical polymerization initiator of these photocurable compounds, a photopolymerization initiator is preferable, and among them, an alkylphenone compound or a phosphine oxide compound is preferable. In particular, a compound having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is preferable. The compound that initiates cationic polymerization, e.g., diazonium, ammonium, iodonium, sulfonium, aromatic onium compounds such as phosphonium ^{_{B (C 6 F 5) 4}} -, PF 6 -, AsF 6 -, SbF 6 - , CF ₃ SO ₃ ^- ionic polymerization initiator or sulfonic acid sulfonated materials that generate a such as salts, halides or generates hydrogen halide, can be mentioned nonionic polymerization initiator such as iron arene complex. In particular, a sulfonate that generates a sulfonic acid that is a nonionic polymerization initiator and a halide that generates a hydrogen halide are preferable.

  Examples of the polymerization initiator include the following compounds.

  Next, an image forming apparatus according to the embodiment of the present invention will be described.

  An image forming apparatus 1 shown in FIG. 1 is a digital image forming apparatus, and includes an image reading unit A, an image processing unit B, an image forming unit C, and a transfer paper transport unit D as a transfer paper transport unit. Yes.

  An automatic document feeder that automatically conveys the document is provided above the image reading unit A. The document placed on the document table 11 is separated and conveyed by the document conveyance roller 12 to the reading position 13a. The image is read. The document after the document reading is completed is discharged onto the document discharge tray 14 by the document transport roller 12.

  On the other hand, the image of the original when placed on the platen glass 13 is read at a speed v of the first mirror unit 15 including the illumination lamp and the first mirror constituting the scanning optical system, and the V-shaped first image is located. Reading is performed by the movement of the second mirror unit 16 including the two mirrors and the third mirror in the same direction at the speed v / 2.

  The read image is formed on the light receiving surface of the image sensor CCD, which is a line sensor, through the projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (luminance signal) and then A / D converted, and the image processing unit B performs processing such as density conversion and filter processing. Then, the image data is temporarily stored in the memory.

  In the image forming unit C, as an image forming unit, a drum-shaped photoconductor 21 as an image carrier, a charging means (charging step) 22 for charging the photoconductor 21 on the outer periphery thereof, and a surface potential of the charged photoconductor. Potential detecting means 220 for detecting the toner, developing means (developing process) 23, transfer / conveying belt device 45 serving as a transferring means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and light discharging means (light discharging process). PCL (precharge lamps) 27 are arranged in the order of operation. Further, on the downstream side of the developing means 23, a reflection density detecting means 222 for measuring the reflection density of the patch image developed on the photosensitive member 21 is provided. As the photosensitive member 21, the organic photosensitive member according to the present invention is used, and the photosensitive member 21 is driven and rotated in the clockwise direction shown in the drawing.

  After the rotating photosensitive member 21 is uniformly charged by the charging unit 22, an image based on an image signal called from the memory of the image processing unit B by an exposure optical system as an image exposure unit (image exposure step) 30 is used. Exposure is performed. The exposure optical system as the image exposure means 30 as the writing means uses a laser diode (not shown) as a light source, and the optical path is bent by the reflection mirror 32 via the rotating polygon mirror 31, the fθ lens 34, and the cylindrical lens 35, and main scanning is performed. Therefore, image exposure is performed on the photoconductor 21 at the position Ao, and an electrostatic latent image is formed by rotation (sub-scanning) of the photoconductor 21. In one example of the present embodiment, the character portion is exposed to form an electrostatic latent image.

  In the image forming apparatus of the present invention, when forming an electrostatic latent image on a photoreceptor, a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 1000 nm is used as an image exposure light source. By using these image exposure light sources, the exposure dot diameter in the writing direction is narrowed down to 10 to 100 μm, and digital exposure is performed on the organic photoreceptor, so that it is 400 dpi (dpi: the number of dots per 2.54 cm) or more. A high-resolution electrophotographic image of 2500 dpi can be obtained.

The exposure dot diameter refers to the length of the exposure beam along the main scanning direction (Ld: measured at the maximum length) in a region where the intensity of the exposure beam is 1 / e ² or more of the peak intensity.

The light beams used have a solid scanner such as the scanning optical system and LED using a semiconductor laser, there is a Gaussian distribution and Lorentz distribution, etc. also the light intensity distribution is in each 1 / e ² or more regions of peak intensity The exposure dot diameter according to the present invention is used.

  The electrostatic latent image on the photoconductor 21 is reversely developed by the developing unit 23, and a visible toner image is formed on the surface of the photoconductor 21. In the image forming method of the present invention, a developer using a toner containing an antioxidant is used for the developing means.

  In the transfer paper transport section D, paper feed units 41 (A), 41 (B), and 41 (C) are provided below the image forming unit as transfer paper storage means for storing transfer paper P of different sizes. Further, a manual paper feeding unit 42 for manually feeding paper is provided on the side, and the transfer paper P selected from any of them is fed along the transport path 40 by the guide roller 43 and fed. The transfer paper P is temporarily stopped by a pair of paper feed registration rollers 44 that correct the inclination and bias of the transfer paper P to be transferred, and then fed again. The transport path 40, the pre-transfer roller 43a, and the paper feed path 46 The toner image on the photosensitive member 21 is transferred onto the transfer paper P by the transfer pole 24, the separation pole 25, the nail separation means 250, and the like at the transfer position Bo. Separated from the body, After the transfer sheet P is placed conveyed to the transfer conveying belt 454 of the transfer conveyor belt device 45, it is conveyed to the fixing unit 50 by the transfer conveyor belt device 45.

  The fixing unit 50 includes a fixing roller 51 and a pressure roller 52. By passing the transfer paper P between the fixing roller 51 and the pressure roller 52, the toner is fixed by heating and pressing. After the toner image has been fixed, the transfer paper P is discharged onto the paper discharge tray 64.

  The above describes the state in which image formation is performed on one side of the transfer paper. However, in the case of double-sided copying, the paper discharge switching member 170 is switched, the transfer paper guide 177 is opened, and the transfer paper P is indicated by a broken arrow. Conveyed in the direction.

  Further, the transfer paper P is transported downward by the transport mechanism 178 and switched back by the transfer paper reversing unit 179, and the rear end portion of the transfer paper P becomes the leading end portion and transported into the duplex copying paper supply unit 130. The

  The transfer paper P is moved in a paper feed direction by a conveyance guide 131 provided in the double-sided copy paper supply unit 130, the transfer paper P is re-fed by the paper supply roller 132, and the transfer paper P is guided to the conveyance path 40. .

  Again, as described above, the transfer paper P is conveyed in the direction of the photosensitive member 21, the toner image is transferred to the back surface of the transfer paper P, fixed by the fixing unit 50, and then discharged onto the paper discharge tray 64.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge, and this unit is configured to be detachable from the apparatus main body. Also good. In addition, a process cartridge is formed by integrally supporting at least one of a charger, an image exposure device, a developing device, a transfer or separation device, and a cleaning device together with a photosensitive member, and a single unit that is detachable from the apparatus main body. It is good also as a structure which can be attached or detached using guide means, such as a rail of an apparatus main body.

  FIG. 2 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y, an exposure unit (exposure step) 3Y, and a developing unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A unit (developing step) 4Y, a primary transfer roller 5Y as a primary transfer unit (primary transfer step), and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and image exposure means 3Y, 3M, 3C and 3Bk, rotating developing means 4Y, 4M, 4C and 4Bk, and cleaning means 6Y, 6M, 6C and 6Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning unit 6Y or the cleaning blade 6Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (image forming unit), and this image forming unit is connected to the apparatus main body. It may be configured to be detachable. In addition, at least one of a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachable from the apparatus main body. A single image forming unit may be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a transfer support for a toner image formed on a photosensitive member such as an intermediate transfer member or a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

  Next, FIG. 3 shows a color image forming apparatus according to another embodiment of the present invention (a copy having at least a charging means, an exposure means, a plurality of developing means, a transfer means, a cleaning means and an intermediate transfer member around the organic photoreceptor). FIG. The belt-shaped intermediate transfer body 70 uses an elastic body having a medium resistance.

  Reference numeral 1 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotationally driven in a counterclockwise direction indicated by an arrow at a predetermined peripheral speed.

  In the rotation process, the photoreceptor 1 is uniformly charged to a predetermined polarity and potential by a charging means (charging process) 2, and then time-series electric digital of image information by an image exposure means (image exposure process) 3 (not shown). An electrostatic latent image corresponding to the yellow (Y) color component image (color information) of the target color image is formed by receiving image exposure by scanning exposure light or the like by a laser beam modulated in accordance with the pixel signal. The

  Then, the electrostatic latent image is developed with yellow toner as the first color by yellow (Y) developing means: developing step (yellow color developing device) 4Y. At this time, the second to fourth developing means (magenta developer, cyan developer, black developer) 4M, 4C, and 4Bk are turned off and do not act on the photosensitive member 1. The first color yellow toner image is not affected by the second to fourth developing units.

  The intermediate transfer member 70 is stretched by rollers 79a, 79b, 79c, 79d, and 79e, and is driven to rotate in the clockwise direction at the same peripheral speed as the photosensitive member 1.

  The first color yellow toner image formed and supported on the photosensitive member 1 is applied to the intermediate transfer member 70 from the primary transfer roller 5a in the process of passing through the nip portion between the photosensitive member 1 and the intermediate transfer member 70. The intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 70 by the electric field formed by the primary transfer bias.

  The surface of the photoreceptor 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 6a.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black (black) toner image are sequentially superimposed and transferred onto the intermediate transfer body 70 to correspond to the target color image. A superimposed color toner image is formed.

  The secondary transfer roller 5b is supported in parallel with the secondary transfer counter roller 79b so as to be separated from the lower surface of the intermediate transfer body 70.

  A primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive member 1 to the intermediate transfer member 70 is opposite in polarity to the toner and is applied from a bias power source. The applied voltage is, for example, in the range of +100 V to +2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive member 1 to the intermediate transfer member 70, the secondary transfer roller 5b and the intermediate transfer member cleaning means 6b can be separated from the intermediate transfer member 70. is there.

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer member 70 is transferred to the transfer material P, which is the second image carrier, the secondary transfer roller 5b is brought into contact with the belt of the intermediate transfer member 70. At the same time, the transfer material P is fed from the pair of paper registration rollers 23 through the transfer paper guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 5b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 5b from a bias power source. By this secondary transfer bias, the superimposed color toner image is transferred (secondary transfer) from the intermediate transfer body 70 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is introduced into the fixing means 24 and heated and fixed.

  The image forming apparatus of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers. The present invention can be widely applied to such devices.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In the following text, “part” means “part by mass”.

(Preparation of photoreceptor 1)
The surface of the cylindrical aluminum support was cut to prepare a conductive support having a surface roughness Rz = 0.8 (μm).

<Intermediate layer>
An intermediate layer coating solution having the following composition was prepared.
Polyamide resin X1010 (manufactured by Daicel Degussa Co., Ltd.) 1 part Titanium oxide SMT500SAS (manufactured by Teika) 1.1 parts ethanol 20 parts Dispersion was carried out for 10 hours in a batch manner using a sand mill as a disperser.

  It apply | coated by the dip coating method so that it might become a film thickness of 2 micrometers after drying for 20 minutes at 110 degreeC on the said support body using the said coating liquid.

<Charge generation layer>
Charge generation material: Y-titanyl phthalocyanine (X-ray diffraction spectrum by Cu-Kα characteristic X-ray having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 °) 50 parts Polyvinyl butyral resin (# 3000-K: manufactured by Denki Kagaku Kogyo Co., Ltd.) 10 parts methyl ethyl ketone 700 parts cyclohexanone 300 parts were mixed and dispersed for 15 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm.

<Charge transport layer>
Charge transport material: CTM-A of exemplified compound 150 parts Binder: exemplified compound A-1 (A-1 having n of 500) 300 parts hindered phenol compound (AO-3) 15 parts toluene / tetrahydrofuran = 1/9 vol% 2000 parts silicon oil (KF-96: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part was mixed and dissolved to prepare a charge transport layer coating solution. The coating liquid was dried on the charge generation layer by dip coating at 110 ° C. for 60 minutes to form a charge transport layer having a thickness of 18 μm.

<Protective layer>
Metal oxide fine particles (titanium oxide having a number average primary particle size of 5 nm surface-treated with S-4 having the same mass as the metal oxide particles) 100 parts Polymerizable compound (Exemplary Compound Mc-31) 100 parts Polymerization initiator (Exemplary Compound 1-6) 15 parts hindered phenol compound (AO-8) 6 parts 2-butyl alcohol 100 parts This protective layer coating solution is applied onto the above charge transport layer using a circular amount-regulating coating device to protect it. A layer was formed. After the protective layer is dried, the distance from the light source to the surface of the photoreceptor is set to 100 mm under a nitrogen stream using a metal halide lamp, and ultraviolet light is irradiated for 1 minute at a lamp output of 4 kW to protect a dry film thickness of 3.0 μm. A layer was formed to prepare the photoreceptor 1.

Production of photoconductors 2 to 10 Photoconductors 2 to 10 were produced in the same manner except that the materials used for the charge transport layer and the protective layer of photoconductor 1 were changed as shown in the list of Table 1.

Photoreceptor 11 (polycarbonate was used as the binder for the protective layer)
Photoreceptor 11 was produced in the same manner as Photoreceptor 1 except that the protective layer was formed as follows in the production of Photoreceptor 1.

<Protective layer>
Metal oxide fine particles (number average primary particle size 30 nm silica surface-treated with methyl hydrogen polysiloxane having the same mass as metal oxide particles) 100 parts binder (polycarbonate having the following structure: weight average molecular weight 20,000) 100 parts hindered Phenol compound (AO-8) 6 parts Isopropyl alcohol 500 parts The above components were dispersed using a sand mill for 10 hours to prepare a protective layer coating solution. A protective layer was applied using a circular slide hopper applicator on the photoreceptor on which the coating solution had been prepared up to the charge transport layer. After coating, the film was dried at 100 ° C. for 50 minutes to obtain a protective layer having a thickness of 3 μm.

Photoconductor 12 (without protective layer)
Photoconductor 12 was prepared in the same manner as in preparation of photoconductor 1, except that the protective layer was removed.

Photoconductor 13 (there is no protective layer and a hindered amine compound was used for the charge transport layer)
In preparation of the photoreceptor 2, the photoreceptor 13 is the same as the photoreceptor 2 except that the protective layer is removed and the following hindered amine compound (AO-30) is used instead of the hindered phenol AO-8 in the charge transport layer. Was made.

Photoconductor 14 (excluding the hindered phenolic compound in the charge transport layer)
Photoreceptor 14 was produced in the same manner as Photoreceptor 1, except that the hindered phenol compound (AO-8) in the charge transport layer was omitted in the production of Photoreceptor 1.

Photoconductor 15 (change the binder of the charge transport layer to TPX)
Photoreceptor 15 was produced in the same manner as Photoreceptor 1, except that the binder of the charge transport layer was changed to a resin having the following structure in production of Photoreceptor 1.

Photoconductor 16 (change the binder of the charge transport layer to polycarbonate)
Photoconductor 16 was prepared in the same manner as Photoconductor 1, except that the binder of the charge transport layer was changed to the polycarbonate resin used in the protective layer of the photoconductor 11 in the preparation of Photoconductor 1.

  Charge transporting substances CTM-A to CTM-D represent compounds having the following structures.

[Evaluation 1]
<Crack test>
In the photoconductors 1 to 16 excluding the photoconductors 11 to 13, the time from application of the protective layer to UV irradiation is cured in 1 hour and 3 hours, and the presence or absence of cracks on the drum surface is visually determined. did. In addition, the photosensitive member 11 is the time from application of the protective layer to heat drying, and the photosensitive members 12, 13 are the time from application of the charge transport layer to heat drying, and the presence or absence of cracks on the drum surface. Judged.
A: No cracking even after 3 hours (no problem in production)
○: Cracks do not occur after 1 hour, but cracks occur within 3.0 hours (within production tolerance)
×: Cracks generated in 1 hour (production problems)
[Evaluation 2]
<Charging characteristics>
About the above photoreceptors 1-16, the same photoreceptor film 1-16 was produced except having replaced the aluminum support body with the aluminum vapor deposition film.
Evaluation Conditions The surface potential when the feedback current Ir = −100 μA and the static method (STAT6) was set by EPA8300 (Kawaguchi Electric Manufacturing Co., Ltd.) was measured.
A: Negative charge (good) with surface potential higher than | 1200 | V
○: Negative charging with surface potential of | 1200 to 1100 | V (no problem in practical use)
×: Negative charge with surface potential lower than | 1100 | V (problem in practical use)
[Evaluation 3]
Basically, the photoconductors 1 to 16 have a configuration shown in FIG. 2 and are a commercially available full-color multifunction machine bizhub PRO C6500 modified machine (manufactured by Konica Minolta Business Technologies, Inc .; 600 dpi, 780 nm semiconductor laser exposure light, reversal development Since the full-color multifunction peripheral has four image forming units, the photosensitive members of the respective image forming units are the same type of photosensitive member (for example, four photosensitive members in the case of the photosensitive member 1). The evaluation was performed in the same manner by preparing the photosensitive member 1. Each evaluation was performed on an A4 image of a YMCBk color printing rate of 2.5% on neutral A4 paper under the conditions of 30 ° C. and 80% RH. The printing durability test for 100,000 sheets was performed, and the following evaluation items were evaluated.

  In the printing durability test, the charging condition for the photosensitive member was set to -700V.

<Potential stability>
In the printing durability test, the initial portion and the exposed portion potential after 100,000 sheets and the unexposed portion potential were measured by installing an electrometer at the position of the developing means.

(Exposed part potential)
A: Solid exposure area potential is less than 30 V (good) after initial and 100,000 sheets
○: Solid exposed portion potential is 30 to 80 V after initial and 100,000 sheets later (no problem in practical use)
X: Solid exposed area potential is greater than 80 V after initial and 100,000 sheets (problematic problem)
(Unexposed area potential)
A: Solid unexposed portion potential is less than 50 V after initial and 100,000 sheets (good)
○: Solid unexposed portion potential is 50 to 100 V after initial and 100,000 sheets (no problem in practical use)
X: Solid exposed portion potential is greater than 100 V after initial and 100,000 sheets (problematically problematic)
<Gas resistance>
The digital copy machine bizhub PRO C6500 modified machine was subjected to a printing durability test in a high-temperature and high-humidity environment (HH: 33 ° C., 80 RH%), and left for 3 hours after 50,000 sheets and 100,000 sheets respectively. Then, a halftone image having a density of 0.4 was copied from the original image, and the occurrence of a white belt-like image generated due to adhesion of active gas on the photoconductor was visually determined on the copy image.

A: No white band is observed (good)
○: White belts appear to be blurred (no problem in practical use)
×: White belt-like occurrence is clearly seen (practical problem)
The evaluation results are summarized in Table 2 below.

  As is clear from Table 2, the photoreceptors 1 to 12 in the invention of the present application have obtained practical results or more in each evaluation item, but the protective layer of the photoreceptor is a combination no. In 13, 14, 15, and 16, any evaluation item has a problem in practicality.

10Y, 10M, 10C, 10Bk image forming unit 1Y, 1M, 1C, 1Bk photoconductor 2Y, 2M, 2C, 2Bk charging means 3Y, 3M, 3C, 3Bk exposure means

Claims (6)

  An organic photoreceptor in which an intermediate layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive support, wherein the charge transport layer contains a cyclic olefin resin and a hindered phenol compound. Photoconductor. The organophotoreceptor according to claim 1, wherein the cyclic olefin resin is a resin having a repeating unit represented by the following general formula (1) or general formula (2).

(In the general formula (1), R ₁₁ and R ₁₂ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted carbonyl group. R ₁₁ and R ₁₂ may be bonded to each other to form a ring, n represents an integer of 20 to 5000, and * is a junction of repeating units.)

(In General Formula (2), R ₁ represents a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, or an alkoxy group, R ₂ represents hydrogen or —COOR ₂ , and R ₂ represents an alkyl group or a silyl group. Represents an integer of 20 to 5000, and * is a junction of repeating units.)   The organic photoreceptor according to claim 1, wherein the organic photoreceptor has a protective layer on the charge transport layer and contains metal oxide particles in the protective layer.   4. The organophotoreceptor according to claim 3, wherein the protective layer is a protective layer formed by a polymerization reaction between the metal oxide particles surface-treated with a polymerizable compound and the polymerizable compound.   5. The image forming apparatus according to claim 1, wherein at least a charging unit, an exposing unit, and a developing unit are provided around the organic photoconductor to repeatedly form an image. An image forming apparatus characterized by being a body.   A process cartridge used in the image forming apparatus according to claim 5 includes at least one of the organic photosensitive member according to any one of claims 1 to 4 and at least one of a charging unit, an image exposing unit, and a developing unit. And a process cartridge configured to be removable from and into the image forming apparatus.

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