JP2008076809A - Organic photoreceptor, image forming method, image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoreceptor in which an increase in a potential of an exposed portion is small and favorable picture with sufficient image density and no fog can be obtained upon forming an image at a high process speed in a short Ted (an interval time between exposure and development), and to provide an image forming method, an image forming apparatus and a process cartridge using the above organic photoreceptor. <P>SOLUTION: The organic photoreceptor has a photosensitive layer on a conductive support and is characterized in that the photosensitive layer contains a charge generating substance and a charge transporting substance and that at least one of the charge transporting substance is a compound having stereoisomers in which the content of trans-trans isomers is 95.0 to 100.0%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic photoreceptor used in the field of copying machines and printers, and an image forming method, an image forming apparatus, and a process cartridge using the organic photoreceptor.

  Electrophotographic photoreceptors (hereinafter also simply referred to as photoreceptors) are mainly organic photoreceptors that are excellent in advantages such as pollution and ease of manufacturing, from inorganic photoreceptors such as Se, arsenic, arsenic / Se alloys, CdS, and ZnO. On the other hand, organic photoreceptors using various materials have been developed.

  In recent years, function-separated type photoconductors in which charge generation and charge transport functions are assigned to different materials have become the mainstream, and in particular, stacked organic photoconductors with a charge generation layer and a charge transport layer are widely used. It has been.

  As a useful charge transporting material, there is a charge transporting material which is a stereoisomer mixture of bis (arylethenylphenyl) aniline compounds and the content of the maximum isomer component in the stereoisomer mixture is 40 to 90% by mass. Known (Patent Document 1). The charge transport material has been reported to improve compatibility with the binder of the charge transport layer, improve image defects such as black spots, and improve electrophotographic properties (such as cuff and image density).

  In recent years, however, the demand for printing digital images on personal computers and the like has increased, and the development of electrophotographic high-speed color printers and printers for light printing has progressed in response to such demands.

  The high-speed printer for light printing and the printer adopting the tandem method are required to have a high process speed. For example, when printing 25 sheets of A4 paper per minute, a process speed of about 200 mm / sec is required. Therefore, when a cylindrical organic photoconductor is rotated at a higher process speed, the photoconductor is charged and exposed. Further, the process load (repeated process that the photoconductor undergoes) such as development, transfer, and cleaning is remarkably increased, causing various problems.

In particular, in a printer that requires high-speed characteristics, a large number of originals are printed in a short time, so a charge transport material having high-speed carrier movement characteristics is required. However, the charge described in Patent Document 1 described above is required. With transport materials, the mobility required for these high-speed printers cannot be ensured, and the residual potential increases greatly when printing many sheets.
JP 2003-270813 A

  An object of the present invention is to provide an organic photoreceptor having high speed characteristics, good potential stability, high image density, and no fogging in view of the above-mentioned problems of the prior art. , An organic photoreceptor capable of obtaining a good image quality with a small increase in the potential of the exposed portion, a sufficient image density and no fog when performing image formation at a high process speed with a short Ted, and the organic photoreceptor The present invention provides an image forming method, an image forming apparatus, and a process cartridge.

As a result of detailed studies on the above problems, the present inventors have found that the charge transport material in the photosensitive layer of the organophotoreceptor contains more trans-trans form than the charge transport material of the conventional stereoisomer mixture. In addition, the present inventors have discovered a stereoisomeric charge transport material having improved compatibility with the binder, and found that the use of such a charge transport material can solve the problems of the present invention in a high-speed process with a short Ted. The present invention has been completed. That is, the object of the present invention is achieved by using an organic photoreceptor having the following constitution.
1. In an organic photoreceptor having a photosensitive layer on a conductive support, the photosensitive layer contains a charge generation material and a charge transport material, and at least one of the charge transport materials is represented by the following general formula (1). An organophotoreceptor which is a compound having an isomer and has a trans-trans content of 95.0% or more and 100.0% or less.

[In the general formula (1), R ₁ and R ₂ each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n and m is an integer of 0-4. ]
2. 2. The organophotoreceptor according to 1 above, wherein the organophotoreceptor has an intermediate layer between the conductive support and the photosensitive layer.
3. 3. The organophotoreceptor according to 2 above, wherein the intermediate layer contains N-type semiconductive fine particles and a binder resin.
4). Cylindrical organic photoreceptor, charging means, exposure means, developing means, transfer means, and cleaning means each having a Ted (exposure-development time) of 30 m · secs to 200 m · secs on the organic photoreceptor In the image forming method for forming an electrophotographic image, the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge generation material and a charge transport material, and at least of the charge transport material. One is a compound having a stereoisomer represented by the following general formula (1), and the trans-trans isomer content is 95.0% or more and 100.0% or less. Method.

[In the general formula (1), R ₁ and R ₂ each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n and m is an integer of 0-4. ]
5. Cylindrical organic photoreceptor, charging means, exposure means, developing means, transfer means, and cleaning means each having a Ted (exposure-development time) of 30 m · secs to 200 m · secs on the organic photoreceptor In the image forming apparatus for forming an electrophotographic image, the organic photoreceptor has a photosensitive layer on a conductive support, the photosensitive layer contains a charge generation material and a charge transport material, and at least of the charge transport material. One is a compound having a stereoisomer represented by the following general formula (1), and the trans-trans isomer content is 95.0% or more and 100.0% or less. apparatus.

[In the general formula (1), R ₁ and R ₂ each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n and m is an integer of 0-4. ]
6). The organic photoreceptor according to any one of 1 to 3 above and at least one of a charger, an image exposure device, a developing device, a transfer device, and a cleaning device are integrated, and can be taken in and out of the image forming apparatus. A process cartridge characterized by being configured.

  By using the organic photoreceptor, the image forming method, the image forming apparatus, and the process cartridge of the present invention, in the image formation formed at a high process speed, the increase in the exposed portion potential is small, the image density is high, and the fog is not generated. A good electrophotographic image can be formed without occurrence.

  Hereinafter, the present invention will be described in detail.

  The organic photoreceptor of the present invention (hereinafter also simply referred to as a photoreceptor) is an organic photoreceptor having a photosensitive layer on a conductive support, and the photosensitive layer contains a charge generation material and a charge transport material, At least one of the transport materials is a compound having a stereoisomer represented by the general formula (1), and the trans-trans content is 95.0% or more and 100.0% or less. And

  Since the organic photoreceptor of the present invention has the above-described configuration, it is excellent in the formation of an image formed by a high-speed process with a short Ted, the increase in the potential of the exposed portion is small, the image density is high, and no fog is generated. An electrophotographic image can be formed.

  That is, by using a compound containing a stereoisomer of the general formula (1) and having a trans-trans isomer content of 95.0% or more and 100.0% or less as the charge transport material used in the photosensitive layer, The decrease in charge carrier mobility required at a high process speed can be prevented, and even when a large number of prints are made in a short time, the increase in the potential of the exposed area is small, the deterioration of the image density is small, and the occurrence of fogging is also possible. A good electrophotographic image that can be prevented can be produced.

  If the content of the trans-trans isomer is less than 95%, the increase in the exposed portion potential cannot be ignored.

  Here,% of the said content rate represents mol%.

  Even if the trans-trans isomer content of the stereoisomer mixture of the general formula (1) is 95.0% or more and 100.0% or less, the effects as described above are not limited to the solvent solubility and the phase with the binder. By using a charge transport material containing a large amount of such a trans-trans body, the charge transport layer is free from the occurrence of image defects such as white spots and black spots that occur when the compatibility is poor. This is thought to be due to the improvement in the mobility of the charge carriers and the electrophotographic characteristics such as the exposed portion potential.

  Although the compound example of the said general formula (1) with the preferable this invention is given to the following, this invention is not limited to the following compound example. In addition, any of these compounds can have a stereoisomer structure.

  Among the above compound examples, T2 and T3 are particularly preferable.

  The charge transport material of the stereoisomer mixture refers to a compound having an isomeric structure which is caused by a different configuration of atoms or atomic groups in a charge transport material compound having the same chemical structural formula.

  Next, the layer structure of the organic photoreceptor using the charge transport material as described above will be described.

  The organic photoconductor of the present invention means an electrophotographic photoconductor constituted by giving an organic compound at least one of a charge generation function and a charge transport function indispensable for the constitution of the electrophotographic photoconductor. It contains all known organic electrophotographic photoreceptors such as a photoreceptor composed of an organic charge generating material or an organic charge transport material, a photoreceptor composed of a polymer complex with a charge generating function and a charge transport function.

  The constitution of the organic photoreceptor used in the present invention is described below.

Conductive Support The conductive support used for the photoreceptor may be either a sheet or a cylinder, but a cylindrical conductive support is preferred for designing an image forming apparatus compactly. .

  Cylindrical conductive support means a cylindrical support necessary for forming an endless image by rotating. Conductivity is within a range of 0.1 mm or less in straightness and 0.1 mm or less in deflection. A support is preferred. Exceeding the range of straightness and shake makes it difficult to form a good image.

As the conductive material, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ωcm or less at room temperature.

  As the conductive support used in the present invention, one having an alumite film that has been sealed on the surface thereof may be used. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing treatment in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / L, the aluminum ion concentration is 1 to 10 g / L, the liquid temperature is about 20 ° C., and the applied voltage is preferably about 20 V. It is not limited. The average film thickness of the anodized film is usually 20 μm or less, particularly preferably 10 μm or less.

Intermediate layer In the present invention, an intermediate layer having a barrier function may be provided between the conductive support and the photosensitive layer.

  In the present invention, in order to improve the adhesion between the conductive support and the photosensitive layer, or to prevent charge injection from the support, an intermediate layer (including an undercoat layer) is provided between the support and the photosensitive layer. Including) can also be provided. Examples of the material for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units. Of these subbing resins, a polyamide resin is preferable as a resin capable of reducing the increase in residual potential due to repeated use. The film thickness of the intermediate layer using these resins is preferably 0.01 to 0.5 μm.

  Examples of the intermediate layer preferably used in the present invention include an intermediate layer using a curable metal resin obtained by thermosetting an organic metal compound such as a silane coupling agent or a titanium coupling agent. As for the film thickness of the intermediate | middle layer using curable metal resin, 0.1-2 micrometers is preferable.

  Further, the intermediate layer preferably used in the present invention includes an intermediate layer in which N-type semiconductive fine particles subjected to a hydrophobic surface treatment are dispersed in a binder. For example, an intermediate layer in which titanium oxide having an average particle size of 0.01 to 1 μm, which has been surface-treated with silica / alumina treatment and a silane compound, is dispersed in a polyamide resin. The film thickness of such an intermediate layer is preferably 1 to 20 μm.

  The N-type semiconducting fine particles are fine particles having the property of using conductive carriers as electrons. That is, the property that the conductive carrier is an electron is that the N-type semiconducting fine particles are contained in an insulating binder to effectively block hole injection from the substrate, and to convert electrons from the photosensitive layer into electrons. On the other hand, it has the property which does not show blocking property.

Specific examples of the N-type semiconducting fine particles include fine particles of titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), etc. In the present invention, titanium oxide is particularly preferably used. It is done.

  The average particle diameter of the N-type semiconducting fine particles used in the present invention is preferably in the range of 10 nm to 500 nm in the number average primary particle diameter, more preferably 10 nm to 200 nm, and particularly preferably 15 nm to 50 nm. .

  The intermediate layer using N-type semiconducting fine particles whose number average primary particle size is within the above range can be finely dispersed in the layer, has sufficient potential stability, and generates black spots. Has a prevention function.

  For example, in the case of titanium oxide, the number-average primary particle size of the N-type semiconducting fine particles is magnified 10,000 times by observation with a transmission electron microscope, and 100 particles are randomly observed as primary particles. It is measured as the number average diameter.

  The shape of the N-type semiconducting fine particles used in the present invention includes dendritic, needle-like, and granular shapes. For example, in the case of titanium oxide particles, the N-type semiconductive fine particles have a crystalline form. There are anatase type, rutile type and amorphous type, but any crystal type may be used, or two or more crystal types may be mixed and used. Of these, the rutile type is the best.

  One of the hydrophobization surface treatments performed on the N-type semiconductive fine particles of the present invention is a plurality of surface treatments, and the last surface treatment is a reactive organosilicon compound among the plurality of surface treatments. The surface treatment is performed. In addition, at least one of the surface treatments is at least one surface treatment selected from alumina, silica, and zirconia, and finally the surface treatment of the reactive organosilicon compound is performed. It is preferable.

  Alumina treatment, silica treatment, and zirconia treatment are treatments for depositing alumina, silica, or zirconia on the surface of the N-type semiconducting fine particles. Alumina, silica, and zirconia deposited on these surfaces include alumina, silica, Zirconia hydrates are also included. The surface treatment of the reactive organosilicon compound means using a reactive organosilicon compound in the treatment liquid.

  In this way, the surface treatment of the N-type semiconductive fine particles such as titanium oxide particles was performed at least twice, so that the surface of the N-type semiconductive fine particles was uniformly coated (treated), and the surface treatment was performed. When N-type semiconducting fine particles are used in the intermediate layer, a good photoconductor having good dispersibility of N-type semiconductive fine particles such as titanium oxide particles in the intermediate layer and causing no image defects such as black spots. You can get it.

Photosensitive layer The photosensitive layer configuration of the photoreceptor of the present invention may be a single-layer photosensitive layer configuration in which a charge generation function and a charge transport function are provided on one layer on the intermediate layer, but more preferably the function of the photosensitive layer. The charge generation layer (CGL) and the charge transport layer (CTL) may be separated from each other. By adopting a configuration in which the functions are separated, an increase in the residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose. In the negatively charged photoconductor, it is preferable that a charge generation layer (CGL) is formed on the intermediate layer and a charge transport layer (CTL) is formed thereon. In the positively charged photoconductor, the order of the layer configuration is the reverse of that in the negatively charged photoconductor. The most preferred photosensitive layer structure of the present invention is a negatively charged photoreceptor structure having the function separation structure.

  The structure of the photosensitive layer of the function-separated negatively charged photoreceptor will be described below.

Charge generation layer The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.

  A known charge generation material (CGM) can be used as the charge generation material (CGM). For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used. Among these, the CGM that can minimize the increase in residual potential due to repeated use has a three-dimensional and potential structure that can form a stable aggregate structure among a plurality of molecules. Specifically, a phthalocyanine having a specific crystal structure. CGM of pigments and perylene pigments. For example, CGMs such as titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ° with respect to Cu—Kα rays and benzimidazole perylene having a maximum peak at 2θ of 12.4 have little deterioration due to repeated use. Potential increase can be reduced.

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.01 μm to 2 μm.

Charge transport layer In the charge transport layer, a compound having a trans-trans content of 95.0 to 100.0% of the stereoisomer of the general formula (1) is used as a charge transport material (CTM), and CTM is dispersed. Contains a binder resin for film formation. Other substances may contain additives such as antioxidants as necessary.

  As the charge transport material (CTM), a known charge transport material can be used in combination with the charge transport material of the stereoisomer mixture described above. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used in combination. These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  Examples of the resin used for the charge transport layer (CTL) include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, and polycarbonate. Resin, silicone resin, melamine resin, copolymer resin containing two or more of these resin repeating units, and high molecular organic semiconductors such as poly-N-vinylcarbazole in addition to these insulating resins Can be mentioned.

  Most preferred as a binder for these CTLs is a polycarbonate resin. The polycarbonate resin is most preferable in improving the dispersibility and electrophotographic characteristics of CTM. In the case of a photoreceptor having a charge transport layer as a surface layer, a polycarbonate resistant to mechanical abrasion is preferable. As such a polycarbonate, a polycarbonate having an average molecular weight of 40,000 to 25,000 is preferable. Here, the average molecular weight may be any of a number average molecular weight, a weight average molecular weight, and a viscosity average molecular weight. The ratio of the binder resin to the charge transport material is preferably 10 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge transport layer is preferably 15 to 35 μm.

  The charge transport layer preferably contains an antioxidant. Typical examples of the antioxidants are those that prevent the action of oxygen under conditions of light, heat, discharge, etc. on auto-oxidizing substances present in the organic photoreceptor or on the surface of the organic photoreceptor, It is a substance that has the property of inhibiting.

  The charge transport layer may be composed of two or more layers. In this case, a layer structure in which a function as a protective layer is added to the charge transport layer on the surface and the wear resistance with the cleaning blade or the like is enhanced is preferable.

  The charge transport layer preferably has a two-layer structure, and a second charge transport layer serving also as a surface protective layer is preferably provided on the first charge transport layer. The film thickness of the charge transport layer according to the present invention is 15 to 35 μm, and the film thickness refers to the total film thickness in the case of a plurality of charge transport layers. When the total film thickness is less than 15 μm, it is difficult to stably maintain a uniform charging potential of 500 V or more and to maintain a uniform charging potential of the organophotoreceptor. On the other hand, if the film thickness exceeds 35 μm, the diffusion of charge carriers during the formation of the latent image increases, the dot image becomes thick, and the reproducibility of the dot image tends to deteriorate.

  In the present invention, the surface layer (second charge transport layer) preferably contains inorganic fine particles, and is further selected from silica, alumina, titanium oxide and strontium titanate having a number average primary particle size of 20 to 400 nm. It is preferable that the inorganic fine particles be one or more types.

  The number average primary particle size is magnified 10,000 times by observation with a transmission electron microscope, 100 particles are randomly observed as primary particles (excluding agglomerated particles), and measured as the number average diameter of the ferret diameter by image analysis Is done. The ferret diameter (Feret) is defined as a constant tangential diameter defined by the distance between two parallel lines that sandwich the particle.

  These inorganic fine particles may be subjected to surface modification with a surface treatment agent for the purpose of improving dispersibility in the coating liquid and coating film. Examples of general surface treatment agents include silane coupling agents, silazanes, titanate coupling agents, aluminum coupling agents, zircoaluminate coupling agents, zirconium organic compounds, and fatty acid compounds. Further, as surface treatment with an inorganic substance, alumina, zirconia, tin oxide, and silica treatment on the surface of inorganic fine particles are known, and these surface treatments may be applied in the present invention. Of these, fatty acid compounds and silane coupling agents are often useful not only for improving dispersibility but also for reducing the residual potential of the photoreceptor.

  The content of inorganic fine particles in the surface layer is preferably 6 to 30% by mass with respect to the binder resin. If it is less than 6% by mass, a sufficient effect of improving wear resistance cannot be obtained. On the other hand, when the content exceeds 30% by mass, it is difficult to form a uniform film in the surface layer. On the other hand, the wear amount of the photoconductor by the contact member (cleaning blade or charging device) tends to increase.

  As described above, the surface layer of the present invention is preferably configured as the second charge transport layer. That is, it is preferable to include a charge transport material in the surface layer so that charges are not accumulated in the surface layer.

  Further, the surface layer contains a binder resin in which the fine particles and the charge transport material are dispersed to enable film formation. As the binder resin, the same binder resin as the charge transport layer described later may be used, but in order to further enhance the wear resistance of the surface layer, a three-dimensional cured resin such as a siloxane-based resin layer may be used. Good. In addition to this, the surface layer may contain an additive such as an antioxidant.

  The thickness of the surface layer is preferably 0.5 to 10 μm, and more preferably 1 to 8 μm.

  As a method for coating the surface layer, a dipping method, a spray coating method, or a quantity-regulating coating device (a coating device that controls the coating amount to control the film thickness of the surface layer) can be used. In order to control the thickness accurately and cover the lower intermediate layer and the entire photosensitive layer, it is preferable to apply using a quantity-regulating coating device.

  Examples of the amount-regulating coating device include a coating device using a circular slide hopper type coating head or an extrusion type coating head. Among these, a coating device having a circular slide hopper type coating head described later (hereinafter also referred to as a circular slide hopper type coating device or a slide type coating device) is preferably used. A coating apparatus having such a circular coating head has a larger number of cylindrical conductive supports (excluding a part of the upper end) immersed in a coating solution than a dip coating in which coating is performed. Since the surface layer is formed in one way without retaining the dispersion liquid, the dispersed particles of the fine particles are not repeatedly subjected to agglomeration share in the dispersion liquid, and settling of the fine particles in the coating liquid is prevented (dispersion medium). The fine particles have a high specific gravity and tend to settle), and can form a uniform surface layer. Moreover, since a dispersion can be prepared every time the photoreceptor is manufactured, aggregation and sedimentation of the dispersion over time can be prevented, and the lower layer already formed on the cylindrical conductive support can be dissolved at the time of surface layer formation. Since it can be applied, the surface layer having a uniform dispersibility can be formed with little aggregation of fine particles even during coating and drying. In the bead formation coating, the coating film thickness can be accurately controlled by the flow rate of the coating liquid discharged from the coating apparatus, and the optically uniform surface layer can be formed with little variation in the film thickness. As a result, an electrophotographic image with good sharpness can be formed.

  Solvents or dispersion media used for forming layers such as intermediate layers, photosensitive layers and protective layers include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone. , Methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane , Tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cellosolve, etc. And the like. Although this invention is not limited to these, Dichloromethane, 1, 2- dichloroethane, methyl ethyl ketone, etc. are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  As the coating processing method for producing the electrophotographic photosensitive member of the present invention, coating processing methods such as dip coating, spray coating, and circular amount regulation type coating are used. In order to prevent the film from being dissolved as much as possible, and in order to achieve uniform coating processing, it is preferable to use a coating processing method such as spray coating or circular amount regulation type (circular slide hopper type is a typical example). The spray coating is described in detail in, for example, JP-A-3-90250 and JP-A-3-269238, and the circular amount-regulating coating is described in detail in, for example, JP-A-58-189061. Yes.

  Next, the image forming apparatus 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.

  The upper part of the image reading unit A is provided with automatic document feeding means for automatically conveying the document. The document placed on the document placing table 11 is separated and conveyed by the document conveying 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 as a transferring means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and light neutralizing means (light slow charge). PCL (precharge lamp) 27 as a process is 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 method of the present invention, Ted (exposure-development time) refers to the developing sleeve of the developing unit 23 from the position (center of irradiated light) of the photosensitive member irradiated with image exposure such as laser of the image exposing unit. 23S is defined as the process time required to reach the position closest to the photoconductor (moving time of the photoconductor).

  The present invention uses a charge transport material of the above general formula (1) containing a large amount of trans-trans isomers in a high-speed process with a very short Ted of 30 m · sec to 200 m · secs. Image forming method in which the exposed portion potential is reduced, image density lowering and fogging are prevented, and image defects such as white spots that are likely to occur with charge transport materials containing a large amount of trans-trans isomers are prevented, An image forming apparatus can be provided.

  In the image forming apparatus of the present invention, it is preferable to use a semiconductor laser or a light emitting diode as an image exposure light source when an electrostatic latent image is formed on a photoreceptor. By using these image exposure light sources, the beam diameter in the direction of writing main writing (diameter of the beam light) is narrowed down to 10 to 80 μm, and digital exposure is performed on the organic photoconductor, whereby 400 dpi (dpi: per 2.54 cm). High-resolution electrophotographic image of 4800 dpi can be obtained.

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

The light beam used has 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 beam diameter according to the present invention is used.

  In the case where a scatter is seen in the measurement of the beam diameter, 20 dots are measured at random, and the average value is set as the beam diameter of the present invention.

  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, it is preferable to use a polymerized toner as a developer used in the developing means. By using a polymer toner having a uniform shape and particle size distribution in combination with the organic photoreceptor according to the present invention, an electrophotographic image with better sharpness can be obtained.

  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 to the transfer paper P while being transferred to the transfer conveyance belt 454 of the transfer conveyance belt device 45 by the transfer electrode 24 and the separation electrode 25 at the transfer position Bo. Is, transfer sheet P is separated from the photosensitive member 21 surface, 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 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 5Y, 5M, 5C and 5Bk 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 5Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning means 5Y or the cleaning blade 5Y) 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 5Y 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 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 pressure contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b is brought into pressure contact with 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 using the organic photoreceptor of the present invention (a copying machine having at least a charging means, an exposure means, a plurality of developing means, a transfer means, a cleaning means, and an intermediate transfer body around the organic photoreceptor. 1 is a cross-sectional view of a configuration of a laser beam printer). 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

  Next, 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 not activated and do not act on the photoreceptor 1. The yellow toner image of the first color is not affected by the second to fourth developing devices.

  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.

  The 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 has a polarity opposite to that of 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 method of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers. Further, displays, recording, light printing, plate making and facsimiles using electrophotographic technology are applied. 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. “Part” in the sentence represents part by mass.

  Synthesis Example 1 (Synthesis Example of Exemplified Compound T2)

  10 g of the compound represented by the above formula was dissolved in 34 g of phosphorus oxychloride, heated to 50 ° C., and 23 ml of dimethylformamide was added dropwise little by little (heated to 40 to 70 ° C.). The reaction solution was stirred for 15 hours while controlling at around 90 ° C. After allowing to cool to 40 ° C., the excess phosphorus oxychloride is sufficiently hydrolyzed and the precipitated crystals are filtered off, suspended in water and washed, and washing is repeated until the washing solution becomes neutral. 9.33 g (77%) of the bisformyl compound represented were obtained.

  2 g of the bisformyl compound obtained above and 4.3 g of a phosphonate compound represented by the following structural formula were dissolved in 20 ml of tetrahydrofuran (THF). While maintaining the reaction solution at around 25 ° C., 1.5 g of sodium methoxide was added little by little (exothermic). After stirring for 4 hours, 30 ml of water was added and purification was performed by a conventional method to obtain 2.5 g (81%) of yellow crystals. When this yellow crystal was subjected to elemental analysis and mass spectrometry, the results shown in Table 4 below were obtained, and it was confirmed that the compound was Exemplified Compound T2.

Elemental analysis (C ₃₈ H ₃₅ N)
Mass spectrometry (C ₃₈ H ₃₅ N)
Mw (calculated value) = 505
Mw ⁺ (actual value) = 505
The compound of T2 obtained by the above synthesis is referred to as T2-1. As a result of measurement by the following liquid chromatography (HPCL), this T2-1 had a trans-trans isomer content of 98.8%, and the remaining 0.2% was a cis-cis isomer and a cis-trans isomer.

Measurement conditions for liquid chromatography Measuring instrument: Shimadzu LC6A (manufactured by Shimadzu Corporation)
Column: CLC-SIL (manufactured by Shimadzu Corporation)
Detection wavelength: 290 nm
Mobile phase: n-hexane / dioxane = 10-500 / 1
Mobile phase flow rate: about 1 ml / min
Sample (T2) solvent: n-hexane / dioxane = 10/1
Sample (T2): 3 mg / solvent 10 ml
The structural formulas of T2cis-cis, T2trans-trans, and T2cis-trans are shown below.

  The T2-1 obtained above was separated by liquid chromatography, and the trans-trans isomer 100% and the remaining 0.2% were separated into a mixture of the cis-cis isomer and the cis-trans isomer. The trans-trans isomers of 100% and the mixture ratio of 0.2% of the mixture were changed, and the compounds of trans-trans content (charge transport materials) T2-2, T2-3, T2-4, T2-5 was produced.

  The trans-trans isomer of T2 was identified by a characteristic peak appearing in an NMR (nuclear magnetic resonance) spectrum after fractionation by liquid chromatography.

Preparation of photoconductor 1 <Intermediate layer>
Titanium oxide SMT500SAS (first time: silica / alumina treatment, second time:
Methyl hydrogen polysiloxane treatment: Titanium oxide particle size 35 nm: manufactured by Teika Co., Ltd. 300 parts Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 100 parts Methanol 1000 parts Add titanium oxide, polyamide resin and methanol into the same container and use an ultrasonic homogenizer. To prepare a coating solution for the intermediate layer. This coating solution was dip-coated on a cylindrical aluminum substrate (100 mmφ), and heat-cured at 110 ° C. for 1 hour to provide an intermediate layer with a dry film thickness of 4 μm.

<Charge generation layer>
Y-type titanyl phthalocyanine (Maximum peak angle of X-ray diffraction by Cu-Kα characteristic X-ray is 27.3 at 2θ) 60 parts Silicone-modified butyral resin (X-40-1211M: manufactured by Shin-Etsu Chemical Co., Ltd.) 700 parts 2-butanone 2000 The parts were mixed and dispersed for 10 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 0.2 μm.

<Charge transport layer>
Charge transport material (T2-1) 100 parts Polycarbonate (viscosity average molecular weight: 20,000) 100 parts Antioxidant (AO-1 having the following compound structure) 2 parts Dichloromethane 700 parts are mixed and dissolved to apply a charge transport layer A liquid was prepared. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 24 μm.

Preparation of photoconductors 2 to 5 Photoconductor 2 was prepared in the same manner as photoconductor 1 except that the charge transport material (T2-1) used in photoconductor 1 was replaced with T2-2 to T2-5 as shown in Table 1. ~ 5 were made.

Evaluation As an evaluation machine, a Konica Minolta Business Technologies Co., Ltd. digital copying machine, Siotis 7085, which has a structure shown in FIG. 1 (modified so that the peripheral speed of the photosensitive member can be changed and Ted can be changed) is used for the copying machine. Photoconductors 1 to 5 were mounted and evaluated. The evaluation was carried out by evaluating the potential of the photoreceptor and image evaluation using Ted as a parameter as described below.

Evaluation of surface potential of photoconductor using Ted as a parameter The photoconductor surface potential at Ted of 30, 65, and 200 m · sec was evaluated by changing the process speed of each photoconductor.

Charging conditions Charger: Scorotron charger, the initial charging potential immediately after charging is adjusted to -750 V at the exposure position by the controller. At this time, the potential detecting means is adjusted to the exposure irradiation position of the photoreceptor. When measuring the potential, the exposure means and the development means are temporarily removed as necessary.

Potential evaluation Measurement of exposed portion potential In the developing step, the potential detecting means was aligned with the Ted measurement position of the photoreceptor, and the exposed portion potential in the developing step was measured.

  Table 2 shows combinations of each photoconductor and Ted.

Image evaluation The image evaluation was performed by copying an original image in which a character image having a pixel rate of 7%, a human face photo, a solid white image, and a solid black image are divided into ¼ equal parts onto A4 neutral paper. Environmental conditions are normal temperature and humidity (20 ° C, 60% RH), Ted is 30, 65, and 200 m · sec. Continuous 10,000 copies are made to produce halftone, solid white images, and solid black images. Went.

Evaluation Criteria Image Density (Measured using Macbeth RD-918. Measured with a relative reflection density with a paper reflection density of “0”. Evaluated with an image after 10,000 copies.)
A: Black solid image is 1.2 or more B: Black solid image is less than 1.2 to 1.0
×: Black solid image is less than 1.0 fog (solid white image after 10,000 copies is judged by image density)
A: No fogging occurred. B: Occurrence of 0.01 to 0.02 fogging occurred in the image density. X: Occurrence of 0.03 or more fogging occurred in the image density.

  As is apparent from Table 2, combination No. 1 using a photoconductor containing a T2 charge transport material having a trans-trans content of 95.0 to 100.0%. In 1 to 3 and 5 to 7, the exposed area potential is sufficiently lowered, and the image density and fog characteristics are also good. On the other hand, combination No. using a photoconductor having a trans-trans content of 94.0%. In No. 4, the exposed portion potential is high, and the evaluation of image density and fog characteristics is also deteriorated.

Example 2
Production of photoconductors 6 to 10 The charge transport material (T2-1) used in photoconductor 1 was replaced with T3-1 to T3-4 and T3-5, and the isomer mixture ratio was changed as shown in Table 3. Photoconductors 6 to 10 were prepared in the same manner as the photoconductor 1.

  Using the photoreceptors 6 to 10, the same evaluation as in Example 1 was performed in combination with Ted. The results are shown in Table 4.

  As is apparent from Table 4, combination No. 1 using a photoconductor containing a T3 charge transport material having a trans-trans content of 95.0 to 100.0%. In Nos. 8 to 10 and 12 to 14, the exposed portion potential is sufficiently lowered, and the image density and the fog characteristic are also good. On the other hand, combination No. using a photoconductor having a trans-trans content of 94.0%. 11, the exposed portion potential is high, and the evaluation of image density and fog characteristics is also deteriorated.

Example 3
Preparation of photoconductors 11 to 14 In preparation of photoconductor 1, 60 parts of Y-type phthalocyanine pigment in the charge generation layer was changed to 40 parts of Y-type phthalocyanine pigment and 20 parts of perylene pigment having the following chemical structure, and charge transport in the charge transport layer. Photoconductors 11 to 14 were prepared in the same manner as the photoconductor 1 except that 100 parts of the material T2-1 was changed to the charge transport material shown in Table 5 (however, the charge transport materials TR1 and TR2 in Table 5 are A compound having the following structure):

  Using the photoconductors 11 to 14, the evaluation was performed under the condition of Ted of 65 m · sec in the same manner as in Example 1. The results are shown in Table 6.

  As is apparent from Table 6, the photoconductor 11 is a combination of a T2-1 charge transport material having a trans-trans content of 99.8% and a charge transport material TR1 or TR2 having a chemical structure outside the present invention. Combination no. In Nos. 15 and 16, the exposed portion potential is still reduced to a practical level, and the image density and fog characteristics are also good. On the other hand, the combination no. In Nos. 17 and 18, the exposed portion potential is high, and the evaluation of image density and fog characteristics is also deteriorated.

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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 21 Photoconductor 22 Charging means 23 Developing means 24 Transfer pole 25 Separation pole 26 Cleaning device 30 Exposure optical system 45 Transfer conveyance belt apparatus 50 Fixing means 250 Separation claw unit

Claims (6)

In an organic photoreceptor having a photosensitive layer on a conductive support, the photosensitive layer contains a charge generation material and a charge transport material, and at least one of the charge transport materials is represented by the following general formula (1). An organophotoreceptor which is a compound having an isomer and has a trans-trans content of 95.0% or more and 100.0% or less.

[In the general formula (1), R ₁ and R ₂ each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n and m is an integer of 0-4. ] 2. The organic photoreceptor according to claim 1, wherein the organic photoreceptor has an intermediate layer between the conductive support and the photosensitive layer. The organophotoreceptor according to claim 2, wherein the intermediate layer contains N-type semiconductive fine particles and a binder resin. Cylindrical organic photoreceptor, charging means, exposure means, developing means, transfer means, and cleaning means each having a Ted (exposure-development time) of 30 m · secs to 200 m · secs on the organic photoreceptor In the image forming method for forming an electrophotographic image, the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge generation material and a charge transport material, and at least of the charge transport material. One is a compound having a stereoisomer represented by the following general formula (1), and the trans-trans isomer content is 95.0% or more and 100.0% or less. Method.

[In the general formula (1), R ₁ and R ₂ each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n and m is an integer of 0-4. ] Cylindrical organic photoreceptor, charging means, exposure means, developing means, transfer means, and cleaning means each having a Ted (exposure-development time) of 30 m · secs to 200 m · secs on the organic photoreceptor In the image forming apparatus for forming an electrophotographic image, the organic photoreceptor has a photosensitive layer on a conductive support, the photosensitive layer contains a charge generation material and a charge transport material, and at least of the charge transport material. One is a compound having a stereoisomer represented by the following general formula (1), and the trans-trans isomer content is 95.0% or more and 100.0% or less. apparatus.

[In the general formula (1), R ₁ and R ₂ each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n and m is an integer of 0-4. ] The organic photoreceptor according to any one of claims 1 to 3 and at least one of a charger, an image exposure device, a developing device, a transfer device, and a cleaning device are integrated and can be taken in and out of an image forming apparatus. A process cartridge configured as described above.

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