JP4992484B2 - Organic photoreceptor, image forming method and image forming apparatus - Google Patents

Description

  The present invention relates to an organic photoconductor used for electrophotographic image formation, an image forming method, and an image forming apparatus, and more specifically, an organic photoconductor used for electrophotographic image formation used in the field of copying machines and printers, The present invention relates to an image forming method and an image forming apparatus.

  In recent years, there are increasing opportunities to use electrophotographic copying machines and printers in the fields of printing and color printing. In the fields of printing and color printing, there is a strong tendency to demand high-quality digital monochrome images or color images. In response to such a demand, it has been proposed to form a high-definition digital image using a short-wavelength laser beam as an exposure light source (Patent Document 1). However, even if the short-wavelength laser light is used to reduce the dot diameter of the exposure and a fine electrostatic latent image is formed on the electrophotographic photosensitive member, the finally obtained electrophotographic image has sufficient high image quality. The current situation has not been achieved.

  The cause is that the photosensitive characteristics of the electrophotographic photosensitive member and the charging characteristics of the toner of the developer do not have sufficient characteristics necessary for forming a fine dot latent image or forming a toner image.

  That is, as an electrophotographic photoreceptor, an organic photoreceptor developed for a conventional long wavelength laser (hereinafter, simply referred to as a photoreceptor) has poor sensitivity characteristics, and the exposure dot diameter is reduced using a short wavelength laser beam. When the narrowed image exposure is performed, the dot latent image is not clearly formed, and the reproducibility of the dot image tends to deteriorate. This is caused not only by the charge generation layer but also by the charge transport layer. It is necessary to identify and remove the deterioration factors of the materials and additives of each layer with respect to the short wavelength laser.

  As a deterioration factor in the charge transport layer, a charge transport material developed for a conventional organic photoreceptor easily absorbs light having a short wavelength of 300 to 500 nm, and as a result, an electrophotography such as a decrease in sensitivity and an increase in residual potential. It is easy to promote deterioration of characteristics.

In response to such problems, it has been reported that a high quality image can be obtained by combining a benzidine compound with a short wavelength laser (Patent Document 2). However, it is not sufficient, and it is easily deteriorated by an active gas such as ozone or NOx generated by a charger or the like. As a result, image blurring occurs, and the reproducibility of the dot line is also easily deteriorated. A polyarylalkane compound having a phenyl group methyl-substituted at the para-position (Patent Document 3) is also known as a charge transport material, but the compound has high crystallinity and precipitates in the photosensitive layer, resulting in blackness. It is easy to generate image defects such as spots.
JP 2000-250239 A JP 2000-147874 A JP-A-51-93224

  The present invention has been made to solve the above problems. An object of the present invention is to form a high-density electrostatic latent image on an organic photoreceptor using image exposure of a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm, and to detect sensitivity, repetition characteristics, or dot lines. It is to provide an organic photoreceptor having improved reproducibility and the like, and to provide an image forming method and an image forming apparatus using the organic photoreceptor. Another object of the present invention is to form a high-density electrostatic latent image on an organic photoreceptor using image exposure of a semiconductor laser or a light-emitting diode having an oscillation wavelength of 350 to 500 nm, and to detect sensitivity, repetition characteristics, or dots An organic photoreceptor capable of forming a high-quality color image with improved line reproducibility and the like, and an image forming method and an image forming apparatus using the organic photoreceptor.

  As a result of repeated studies on the above problems, the object of the present invention is to form a high-density electrostatic latent image on an organic photoreceptor using image exposure of a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 500 nm. In order to form an electrophotographic image with improved sensitivity, repeatability, dot line reproducibility, etc., it has a low absorption and a relatively large molecular weight for a short wavelength laser beam, etc. The present invention has been completed by finding that it is effective to use a compound having good compatibility with the binder as a charge transport material for an organic photoreceptor. That is, an organic photoreceptor using a polyarylalkane compound represented by the general formula (1) as a charge transporting material as shown below is effective for the above-mentioned problem that is likely to occur with exposure light of a short wavelength laser beam. As a result, the present invention has been completed.

That is, the present invention is achieved by using an organic photoreceptor having the following configuration.
(1) An organic photoreceptor having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a charge transport material represented by the following general formula (1).

[In General Formula (1), R ₁ and R ₂ each independently represent an alkyl group or an aryl group, and R ₁ and R ₂ may be combined to form a cycloalkyl group. R ₃ represents an alkyl group having 1 to 4 carbon atoms, and R ₄ and R ₅ represent an alkyl group. However, l represents an integer of 0 to 4, and m represents an integer of 0 to 5. However, when l and m are each an integer of 2 or more, R ₄ and R ₅ may each independently be a different group within the same R _n . ]
(2) The organophotoreceptor according to (1) above, wherein the photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material.
(3) The organic photoreceptor as described in (1) or (2) above, wherein the charge generating substance is a polycyclic quinone compound.
(4) The organophotoreceptor as described in (1) or (2) above, wherein the charge generating substance is a perylene compound.
(5) An exposure process for forming an electrostatic latent image on an organic photoreceptor using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a writing light source of a light emitting diode, and developing the electrostatic latent image into a toner image An image forming method comprising a developing step, wherein the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge transport material represented by the following general formula (1): Method.

[In General Formula (1), R ₁ and R ₂ each independently represent an alkyl group or an aryl group, and R ₁ and R ₂ may be combined to form a cycloalkyl group. R ₃ represents an alkyl group having 1 to 4 carbon atoms, and R ₄ and R ₅ represent an alkyl group. However, l represents an integer of 0 to 4, and m represents an integer of 0 to 5. However, when l and m are each an integer of 2 or more, R ₄ and R ₅ may each independently be a different group within the same R _n . ]
(6) An exposure unit that forms an electrostatic latent image on an organic photoreceptor using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a light source of a light emitting diode, and visualizes the electrostatic latent image into a toner image. In the image forming apparatus having a developing means, the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge transport material represented by the following general formula (1): apparatus.

[In General Formula (1), R ₁ and R ₂ each independently represent an alkyl group or an aryl group, and R ₁ and R ₂ may be combined to form a cycloalkyl group. R ₃ represents an alkyl group having 1 to 4 carbon atoms, and R ₄ and R ₅ represent an alkyl group. However, l represents an integer of 0 to 4, and m represents an integer of 0 to 5. However, when l and m are each an integer of 2 or more, R ₄ and R ₅ may each independently be a different group within the same R _n . ]

  By using the organophotoreceptor, the image forming method and the image forming apparatus of the present invention, the sensitivity and repeatability with respect to short wavelength laser exposure are improved, a high-definition dot image can be formed, and the dot line reproducibility is improved. It is possible to form a high-quality electrophotographic image that has been improved and the occurrence of image defects such as black spots can be improved.

  Hereinafter, the organic photoreceptor of the present invention will be described in detail.

  The organic photoreceptor of the present invention is an organic photoreceptor having a photosensitive layer on a conductive support, and the photosensitive layer contains the charge transport material represented by the general formula (1).

  The charge transport material of the general formula (1) has a large potential attenuation value per unit exposure amount and an improved repetition characteristic with respect to an exposure light source having a wavelength of 350 to 500 nm, and sharply forms a small-diameter dot latent image. In addition, it is possible to form a high-quality electrophotographic image with improved dot line reproducibility and improved occurrence of image defects such as black spots.

  In addition, the compound (charge transport material) of the general formula (1) according to the present invention can prevent image blur due to an active gas such as ozone or NOx, and can reproduce dot lines with high sensitivity even when a short wavelength laser is used. Organic photoreceptors with good properties can be produced.

In the general formula (1),
R ₁ and R ₂ each independently represents an alkyl group or an aryl group, and R ₁ and R ₂ may be combined together to form a cycloalkyl group. ˜4 alkyl groups are preferred.

R ₄ and R ₅ represent an alkyl group, and the alkyl group is preferably an alkyl group having 1 to 4 carbon atoms.

  Specific examples of the compound of the general formula (1) are illustrated below.

  Hereinafter, a synthesis example of the charge transport material of the general formula (1) according to the present invention will be described using the following reaction formula.

Synthesis Example 1 (CTM-7)
A 200ml 4-head Kolben is equipped with a cooling tube, thermometer and nitrogen inlet tube, and a magnetic stirrer is set. The system is depressurized and completely purged with nitrogen. To this Kolben, (a) 8.1 g, (b) 12.0 g, K ₂ CO ₃ 16 g, Cu powder 8.0 g, and nitrobenzene 40 ml were sequentially added and stirred at 190 ° C. for 30 hours. Reacted. Thereafter, the reaction solution was treated by steam distillation, and then separated and purified by column chromatography using a developing solvent of hexane / toluene (4/1) to obtain 12 g of CTM-7 as a target product. Confirmation of the target product could be confirmed by mass spectrometry and NMR.

  Synthesis Example 2 (CTM-89)

A 200ml 4-head Kolben is equipped with a cooling tube, thermometer, nitrogen inlet tube and calcium chloride tube, and a magnetic stirrer is set. The system is depressurized and completely purged with nitrogen. To this Kolben, 23.0 g of (c), 20.0 g of (d), 0.5 g of CH ₃ SO ₃ H, and 60 ml of acetic acid were sequentially added and reacted at room temperature for 10 hours while stirring. . Thereafter, the reaction solution was poured into toluene / water (120 ml / 120 ml), and the reaction product was extracted with toluene. This was separated and purified by column chromatography using a developing solvent of hexane / toluene (4/1) to obtain 9.7 g of the target product CTM-89. Confirmation of the target product could be confirmed by mass spectrometry and NMR.

  The organophotoreceptor according to the present invention is an organophotoreceptor containing the charge transport material of the general formula (1). The constitution of the organophotoreceptor containing these charge transport materials will be described below.

  In the present invention, the organic photoconductor means an electrophotographic photoconductor constituted by providing an organic compound with at least one of a charge generation function and a charge transport function essential to the configuration of the electrophotographic photoconductor. All known organic photoconductors such as a photoconductor composed of an organic charge generating material or an organic charge transport material, a photoconductor composed of a polymer complex with a charge generating function and a charge transport function are contained.

The constitution of the organophotoreceptor of the present invention is not particularly limited as long as it contains the compound of formula (1) (charge transport material), and examples thereof include the following constitutions;
1) A structure in which a charge generation layer and a charge transport layer are sequentially laminated as a photosensitive layer on a conductive support;
2) A structure in which a charge generation layer, a first charge transport layer, and a second charge transport layer are sequentially laminated as a photosensitive layer on a conductive support;
3) A structure in which a single layer containing a charge transport material and a charge generation material is formed as a photosensitive layer on a conductive support;
4) A structure in which a charge transport layer and a charge generation layer are sequentially laminated as a photosensitive layer on a conductive support;
5) A structure in which a surface protective layer is further formed on the photosensitive layer of the photoreceptors 1) to 5) above.

  The photoconductor may have any of the above configurations. The surface layer of the photoreceptor is a layer in contact with the air interface. When only a single-layer photosensitive layer is formed on the conductive support, the photosensitive layer is the surface layer, and the conductive layer In the case where a single-layered or laminated photosensitive layer and a surface protective layer are laminated on the conductive support, the surface protective layer is the outermost surface layer. In the present invention, the configuration 2) is most preferably used. Note that, regardless of the configuration of the photoreceptor of the present invention, an undercoat layer (intermediate layer) may be formed on the conductive support prior to the formation of the photosensitive layer.

  The charge transport layer means a layer having a function of transporting charge carriers generated in the charge generation layer by photoexposure to the surface of the organic photoreceptor, and the specific detection of the charge transport function is carried out between the charge generation layer and the charge transport layer. It can be confirmed by laminating a transport layer on a conductive support and detecting optical conductivity.

  Next, the layer structure of the organic photoreceptor will be described focusing on the structure of 1) above.

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. The conductive support of the present invention is most preferably an aluminum support. As the aluminum support, one in which components such as manganese, zinc, magnesium and the like are mixed in addition to the main component aluminum is also used.

Intermediate layer In the present invention, an intermediate layer is preferably provided between the conductive support and the photosensitive layer.

  The intermediate layer used in the present invention preferably contains N-type semiconductor particles. The N-type semiconductive particle means a particle whose main charge carrier is an electron. That is, since the main charge carriers are electrons, the intermediate layer containing the N-type semiconductive particles in the insulating binder effectively blocks hole injection from the substrate, and the electrons from the photosensitive layer. In contrast, it has a property of low blocking.

As the N-type semiconductor particles, titanium oxide (TiO ₂ ) and zinc oxide (ZnO) are preferable, and titanium oxide is particularly preferably used.

  As the N-type semiconductor particles, fine particles having a number average primary particle size in the range of 3.0 to 200 nm are used. Particularly, 5 nm to 100 nm is preferable. The number average primary particle diameter is a measured value as an average diameter in the ferret direction by observing 100 particles as primary particles at random by magnifying the fine particles 10,000 times by transmission electron microscope observation and image analysis. N-type semiconducting particles having a number average primary particle size of less than 3.0 nm are difficult to uniformly disperse in the intermediate layer binder, and easily form aggregated particles. Is likely to occur. On the other hand, N-type semiconducting particles having a number average primary particle size larger than 200 nm tend to make large irregularities on the surface of the intermediate layer, and the dot image tends to deteriorate through these large irregularities. In addition, the N-type semiconductive particles having a number average primary particle size larger than 200 nm are likely to precipitate in the dispersion and easily generate aggregates. As a result, the dot image tends to deteriorate.

  The titanium oxide particles have anatase, rutile, brookite, and amorphous forms as crystal forms. Among them, the rutile form titanium oxide pigment or the anatase form titanium oxide pigment has a rectifying property of charge passing through the intermediate layer. In other words, the mobility of electrons is increased, the charging potential is stabilized, the residual potential is prevented from increasing, and the dot image is prevented from deteriorating, which is most preferable as the N-type semiconductor particles of the present invention. .

  N-type semiconductive particles are preferably surface-treated with a reactive organosilicon compound such as a silane coupling agent or a polymer containing methylhydrogensiloxane units.

  As the reactive organosilicon compound, chlorosilane compounds such as methyltrichlorosilane and dimethyldichlorosilane, alkoxysilane compounds such as methyltrimethoxysilane and dimethyldimethoxysilane, and silazane compounds such as hexamethylsilazane can be preferably used.

  On the other hand, the molecular weight of the polymer containing methylhydrogensiloxane units is 1000 to 20000 and has a high surface treatment effect. As a result, the rectifying property of the N-type semiconductor particles is improved, and the N-type semiconductor particles are contained. By using the intermediate layer, the occurrence of black spots is prevented, and good dot image reproducibility is obtained.

The polymer containing a methylhydrogensiloxane unit is preferably a copolymer of a structural unit of-(HSi (CH ₃ ) O)-and a structural unit other than this (other siloxane unit). As other siloxane units, dimethylsiloxane units, methylethylsiloxane units, methylphenylsiloxane units, diethylsiloxane units, and the like are preferable, and dimethylsiloxane is particularly preferable. The proportion of methylhydrogensiloxane units in the copolymer is 10 to 99 mol%, preferably 20 to 90 mol%.

  The methylhydrogensiloxane copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, etc., but a random copolymer and a block copolymer are preferred. In addition to methylhydrogensiloxane, the copolymerization component may be one component or two or more components.

  The intermediate layer coating solution prepared for forming the intermediate layer used in the present invention is composed of a binder resin, a dispersion solvent and the like in addition to the N-type semiconductive particles such as the surface-treated titanium oxide.

  The ratio of the N-type semiconductive particles in the intermediate layer is preferably 1.0 to 2.0 times in terms of the volume ratio of the intermediate layer to the binder resin (when the volume of the binder resin is 1). By using the N-type semiconducting particles of the present invention at such a high density in the intermediate layer, the rectification of the intermediate layer is enhanced, and the increase in residual potential and dot image degradation are effective even when the film thickness is increased. Therefore, a good organic photoreceptor can be formed. Further, such an intermediate layer preferably uses 100 to 200 parts by volume of N-type semiconductive particles with respect to 100 parts by volume of the binder resin.

  On the other hand, the binder resin in which these particles are dispersed to form the layer structure of the intermediate layer is preferably a polyamide resin in order to obtain good dispersibility of the particles, but the polyamide resin shown below is particularly preferable.

  The binder resin for the intermediate layer is preferably an alcohol-soluble polyamide resin. As the binder resin for the intermediate layer of the organic photoreceptor, a resin having excellent solvent solubility is required in order to form the intermediate layer with a uniform film thickness. As such an alcohol-soluble polyamide resin, a copolymerized polyamide resin or a methoxymethylated polyamide resin composed of a chemical structure with few carbon chains between amide bonds such as 6-nylon described above is known. In addition to these resins, polyamide resins having the following chemical structure are preferably used.

  The molecular weight of the polyamide resin is preferably 5,000 to 80,000, more preferably 10,000 to 60,000 in terms of number average molecular weight. When the number average molecular weight is 5,000 or less, the uniformity of the film thickness of the intermediate layer is deteriorated, and the effects of the present invention are not sufficiently exhibited. On the other hand, if it is larger than 80,000, the solvent solubility of the resin is likely to be reduced, and an agglomerated resin is likely to be generated in the intermediate layer, which tends to cause black spots and deterioration of the dot image.

  A part of the polyamide resin is already available on the market. For example, the polyamide resin is sold under the trade names such as Vestamelt X1010 and X4685 manufactured by Daicel Degussa Co., Ltd., and can be prepared by a general polyamide synthesis method. An example of synthesis is given below.

  As the solvent for dissolving the polyamide resin and preparing the coating solution, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol are preferable, It is excellent in the solubility of polyamide and the coating property of the prepared coating solution. These solvents are 30 to 100% by mass, preferably 40 to 100% by mass, and more preferably 50 to 100% by mass in the total solvent. Examples of co-solvents that can be used in combination with the above-mentioned solvent to obtain preferable effects include methanol, benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The thickness of the intermediate layer of the present invention is preferably 0.3 to 10 μm. If the thickness of the intermediate layer is less than 0.5 μm, black spots or the like are likely to occur, and the dot image is likely to deteriorate. If it exceeds 10 μm, the residual potential is likely to increase, and the dot image tends to deteriorate. As for the film thickness of an intermediate | middle layer, 0.5-5 micrometers is more preferable.

Moreover, it is preferable that the said intermediate | middle layer is an insulating layer substantially. Here, the insulating layer has a volume resistance of 1 × 10 ⁸ Ω · cm or more. The volume resistance of the intermediate layer and the protective layer of the present invention is preferably 1 × 10 ⁸ to 10 ¹⁵ Ω · cm, more preferably 1 × 10 ⁹ to 10 ¹⁴ Ω · cm, and further preferably 2 × 10 ⁹ to 1 ×. 10 ¹³ Ω · cm. The volume resistance can be measured as follows.

  Measurement conditions: According to JIS: C2318-1975.

Measuring instrument: Hiresta IP manufactured by Mitsubishi Yuka
Measurement conditions: Measurement probe HRS
Applied voltage: 500V
Measurement environment: 30 ± 2 ℃, 80 ± 5RH%
If the volume resistance is less than 1 × 10 ⁸ , the charge blocking property of the intermediate layer decreases, the occurrence of black spots increases, the potential holding property of the organic photoreceptor deteriorates, and good image quality cannot be obtained. On the other hand, if it is greater than 1 × 10 ¹⁵ Ω · cm, the residual potential tends to increase in repeated image formation, and good image quality cannot be obtained.

Photosensitive layer The photosensitive layer configuration of the photoreceptor of the present invention may be a single-layer photosensitive layer configuration in which the intermediate layer has a charge generation function and a charge transport function in one 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.

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

Charge Generation Layer In the organic photoreceptor of the present invention, it is preferable to use a charge generation material having high sensitivity characteristics in the wavelength region of 350 nm to 500 nm as the charge generation material. As such a charge generating substance, an azo pigment, a perylene pigment, a multisensitive quinone pigment, or the like is preferably used. These pigments can be used in combination. Examples of pigment compounds preferably used in the present invention are shown below.

  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 0.3 μm to 2 μm.

Charge Transport Layer The charge transport layer contains a charge transport material (CTM) and a binder resin that forms a film by dispersing CTM. As other substances, additives such as an antioxidant may be contained in addition to the inorganic fine particles as necessary.

  As the charge transport material (CTM), the charge transport material of the general formula (1) is used, but in addition to this, a known hole transport property (P type) charge transport material (CTM) may be used in combination. Good. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  The total thickness of the charge transport layer is preferably 10 to 25 μm. If the total film thickness is less than 10 μm, it is difficult to sufficiently obtain a latent image potential at the time of development, and image density is lowered and dot reproducibility is liable to be deteriorated. Diffusion of charge carriers generated in the generation layer) increases, and dot reproducibility tends to deteriorate. Further, the thickness of the charge transport layer serving as the surface layer is preferably 1.0 to 8.0 μm.

  Solvents or dispersion media used to form layers such as intermediate layers, charge generation layers, and charge transport 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 cello Lube, and the like. Although this invention is not limited to these, Solvents friendly to global environment, such as tetrahydrofuran and methyl ethyl ketone, are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  Next, as a coating processing method for producing the organic photoreceptor, a coating processing method such as dip coating or spray coating is used in addition to the slide hopper type coating device. For forming the surface layer of the present invention, it is most preferable to use a circular slide hopper type coating apparatus.

  Among the above coating liquid supply type coating apparatuses, the coating method using a slide hopper type coating apparatus is most suitable when the above-described dispersion using a low boiling point solvent is used as the coating liquid, and is a cylindrical photoconductor. In this case, the coating is preferably performed using a circular slide hopper type coating apparatus described in detail in JP-A No. 58-189061 and the like.

  In the coating method using a circular slide hopper type coating apparatus, the slide surface end and the base material are arranged with a certain gap (about 2 μm to 2 mm), so that the base material is not damaged, and layers having different properties are multilayered. Even in the case of forming, it can be applied without damaging the already applied layer. Furthermore, when multiple layers with different properties and dissolved in the same solvent are formed, the time in the solvent is much shorter compared to the dip coating method, so that the lower layer component hardly elutes to the upper layer side, and the coating tank Can be applied without degrading the dispersibility of the inorganic fine particles of the present invention.

  The surface layer of the photoreceptor according to the present invention preferably contains an antioxidant. The surface layer is easily oxidized by an active gas such as NOx or ozone during charging of the photoconductor, and image blur is likely to occur. However, the presence of an antioxidant can prevent image blur. 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. Typical examples include the following compound groups.

  Solvents or dispersion media used to form layers such as intermediate layers, charge generation layers, and charge transport 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 cello Lube, 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.

  Next, an image forming apparatus using the organic photoreceptor according to 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 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 apparatus of the present invention, a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm is used as an image exposure light source when an electrostatic latent image is formed on a photoreceptor. Using these image exposure light sources, the exposure dot diameter in the writing direction is narrowed down to 10 to 50 μm, and digital exposure is performed on the organic photoreceptor, so that it is 600 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 (Ld: measured at the maximum position) along the main scanning direction 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, 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 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 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 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 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

  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, and further displays, recordings, light printing, plate making and facsimiles using electrophotographic technology. 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”.

Production of Photoreceptor 1 Photoreceptor 1 was produced as follows.

Intermediate layer On the washed cylindrical aluminum substrate (10 points surface roughness Rz: processed to 0.81 μm by cutting), the following intermediate layer coating solution was applied by dip coating, and dried at 120 ° C. for 30 minutes. An intermediate layer having a dry film thickness of 5 μm was formed.

  The following intermediate layer dispersion is diluted twice with the same mixed solvent, and is allowed to stand overnight and then filtered (filter; rigesh mesh filter made by Nippon Pole Co., Ltd., nominal filtration accuracy: 5 microns, pressure: 50 kPa). Produced.

(Preparation of intermediate layer dispersion)
Binder resin: (Exemplary polyamide N-1) 1 part Rutile titanium oxide (primary particle size 35 nm; titanium oxide pigment surface-treated with dimethylpolysiloxane having a hydroxyl group at the terminal) 5.6 parts ethanol / n-propyl alcohol / THF (= 45/20/30 mass ratio) 10 parts The above components were mixed and dispersed by a batch method for 10 hours using a sand mill disperser to prepare an intermediate layer dispersion.

Charge generation layer: CGL
Charge generation material (CGM): Exemplified compound CGM-2 24 parts Polyvinyl butyral resin “ESREC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 2-butanone / cyclohexanone = 4/1 (v / v) 300 parts Were mixed and dispersed using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.5 μm on the intermediate layer.

Charge transport layer (CTL)
Charge transport material (Exemplary Compound CTM-7) 225 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical) 300 parts Antioxidant (Exemplary Compound AO-1) 3 parts Dichloromethane 2000 parts Silicon oil (KF-54: Shin-Etsu Chemical Co., Ltd.) ) 1 part was mixed and dissolved to prepare a charge transport layer coating solution 1. This coating solution was applied onto the charge generation layer by a dip coating method and dried at 110 ° C. for 70 minutes to form a charge transport layer 1 having a dry film thickness of 20.0 μm.

Production of photoconductors 2 to 16 Photoconductors 2 to 16 were produced in the same manner as photoconductor 1 except that the type of the charge transport material in the charge transport layer was changed as shown in Table 1 in the production of photoconductor 1. CTMR-1 used for the photoreceptor 15 is a charge transport material of the following benzicine compound, and CTMR-2 used for the photoreceptor 16 is a charge transport material of the following polyarylalkane compound.

<< Evaluation 1 >>
The electrophotographic photosensitive member thus prepared was evaluated as follows using an electrostatic copying paper test apparatus (manufactured by Kawaguchi Electric Co .: EPA-8300).

(sensitivity)
Charge the surface potential of the photoconductor with a corona charger so as to be −700 V, then expose with 400 nm monochromatic light separated by a monochromator, measure the amount of light necessary for the surface potential to decay to −350 V, Sensitivity (E1 / 2) was determined.

  Similarly, the sensitivity in 450 nm and 500 nm monochromatic light was measured.

(Repeat characteristics)
Next, the initial dark portion potential (Vd) and the initial bright portion potential (Vl) are set to around −700 V and −200 V, respectively, and charging and exposure are repeated 3000 times using a monochromatic light of 450 nm, and the fluctuation amount of Vd and Vl ( ΔVd, ΔVl) were measured.

  The results are shown in Table 1.

  In the following table, a minus sign represents a decrease in potential, and a plus sign represents an increase in potential.

(Image evaluation)
A digital copying machine Sitos 7085 (manufactured by Konica Minolta Business Technologies, Inc.) having a configuration shown in FIG. 1 as an evaluation machine (a process for performing 1200 dpi exposure using a 450 nm semiconductor laser as an image exposure light source and a beam diameter of 30 μm) The photoconductors 1 to 15 were mounted on the copying machine and evaluated. Evaluation items and evaluation criteria are shown below.

Evaluation of 1-dot line A 1-dot line and a solid black image were produced on a white A4 paper, and evaluated according to the following criteria.

◎: 1 dot line is reproduced continuously, solid image density is 1.2 or higher (good)
○: 1 dot line is reproduced continuously, but solid image density is less than 1.2 to 1
. 0 or more (no problem in practical use)
×: Even if one dot line is cut and reproduced, or one dot line is continuously reproduced, the solid black image density is less than 1.0 (problem in practical use)
Evaluation of 2-dot line A 2-dot white line was produced in a solid black image and evaluated according to the following criteria.

A: The white line of 2 dot lines is reproduced continuously, and the image density of solid black is 1.2 or more (good)
○: The white line of 2 dot lines is reproduced continuously, but the solid image density is less than 1.2 to 1.0 or more (no problem in practical use)
X: Even if the white line of 2 dot lines is cut and reproduced, or the white line of 2 dot lines is reproduced continuously, the solid image density is less than 1.0 (there is a problem in practical use)
The above-mentioned solid image density is measured using RD-918 manufactured by Macbeth. The relative reflection density was measured with the paper reflection density set to “0”.

Evaluation of Image Defects Using the digital copy machine Siotis 7085 modified, 10,000 sheets were printed with a character image with a pixel rate of 10%, and then white images were printed to evaluate black spots.

  ○: The occurrence of black spots which are found visually is small (5 or less in A4 paper), and there is no practical problem.

  X: Many black spots discovered visually (6 or more in A4 paper) have practical problems.

  The results are shown in Table 1.

  As is clear from Table 1, the organic photoreceptors 1 to 14 using the charge transport material of the compound of the general formula (1) have excellent sensitivity characteristics with respect to irradiation light of 400 to 500 nm such as short wavelength laser light. In addition, the reproducibility of 1-dot lines and 2-dot lines is excellent even in image evaluation using a short wavelength laser beam of 405 nm. On the other hand, the photoconductor 15 using the CTMR-1 charge transport material of the comparative example is relatively inferior to the photoconductors 1 to 14 of the present invention in evaluation of sensitivity and repeatability, and in image evaluation. However, the deterioration of the reproducibility of one dot line is large. Further, the photoreceptor 16 using the CTMR-2 charge transport material of the comparative example has many black spots and has a problem in practicality.

Preparation of photoconductors 17 to 20 In preparation of photoconductors 13 to 16, the charge generation material of the charge generation layer was changed in the same manner except that the exemplary compound CGM-2 (polycyclic quinone compound) was changed to CGM-1 (perylene compound). Photoconductors 17 to 20 were produced. The photoreceptors 17 to 20 were evaluated in the same manner as the photoreceptor 1. The evaluation results are shown in Table 2.

  As is apparent from Table 2, even when a perylene compound is used as the charge generation material, the organic photoreceptors 17 and 18 using the charge transport material of the compound of the general formula (1) are photosensitive using the charge transport material of the comparative example. Compared to the body 19, it has excellent sensitivity characteristics and repetitive characteristics with respect to irradiation light of 400 to 500 nm such as short wavelength laser light, and it is one dot line in image evaluation using a short wavelength laser light of 405 nm. And 2 dot line reproducibility is excellent. Further, the photoconductor 20 of the comparative example has a lot of black spots.

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

10Y, 10M, 10C, 10Bk Image forming unit 1Y, 1M, 1C, 1Bk Photoconductor 2Y, 2M, 2C, 2Bk Charging unit 3Y, 3M, 3C, 3Bk Exposure unit 4Y, 4M, 4C, 4Bk Developing unit

Claims (6)

An organic photoreceptor having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a charge transport material of the following general formula (1).

[In General Formula (1), R ₁ and R ₂ each independently represent an alkyl group or an aryl group, and R ₁ and R ₂ may be combined to form a cycloalkyl group. R ₃ represents an alkyl group having 1 to 4 carbon atoms, and R ₄ and R ₅ represent an alkyl group. However, l represents an integer of 0 to 4, and m represents an integer of 0 to 5. However, when l and m are each an integer of 2 or more, R ₄ and R ₅ may each independently be a different group within the same R _n . ]
However, the case where the polyarylate resin containing the repeating structural unit represented by the following formula (1) ′ is contained is excluded.

(In Formula (1) ′, R ^{11 to} R ¹⁸ and R ^{21 to} R ²⁸ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group, and X represents a single bond, an oxygen atom, A sulfur atom or a divalent group having a structure represented by the following formula (2) is shown.

In the formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group, or R ³¹ and R ³² are bonded to each other. A cycloalkylidene group or a fluorenylidene group to be formed is shown. )   The organophotoreceptor according to claim 1, wherein the photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material.   The organophotoreceptor according to claim 1, wherein the charge generation material is a polycyclic quinone compound.   The organophotoreceptor according to claim 1, wherein the charge generation material is a perylene-based compound. An exposure process for forming an electrostatic latent image on a photoconductor using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a light emitting diode writing light source, and a developing process for visualizing the electrostatic latent image into a toner image In the image forming method, the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge transport material represented by the following general formula (1).

[In General Formula (1), R ₁ and R ₂ each independently represent an alkyl group or an aryl group, and R ₁ and R ₂ may be combined to form a cycloalkyl group. R ₃ represents an alkyl group having 1 to 4 carbon atoms, and R ₄ and R ₅ represent an alkyl group. However, l represents an integer of 0 to 4, and m represents an integer of 0 to 5. However, when l and m are each an integer of 2 or more, R ₄ and R ₅ may each independently be a different group within the same R _n . ]
However, the case where the polyarylate resin containing the repeating structural unit represented by the following formula (1) ′ is contained is excluded.

(In Formula (1) ′, R ^{11 to} R ¹⁸ and R ^{21 to} R ²⁸ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group, and X represents a single bond, an oxygen atom, A sulfur atom or a divalent group having a structure represented by the following formula (2) is shown.

In the formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group, or R ³¹ and R ³² are bonded to each other. A cycloalkylidene group or a fluorenylidene group to be formed is shown. ) An exposure unit that forms an electrostatic latent image on a photoconductor using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a light source of a light emitting diode; and a developing unit that visualizes the electrostatic latent image into a toner image. An image forming apparatus comprising: an organic photoreceptor having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a charge transport material represented by the following general formula (1).

[In General Formula (1), R ₁ and R ₂ each independently represent an alkyl group or an aryl group, and R ₁ and R ₂ may be combined to form a cycloalkyl group. R ₃ represents an alkyl group having 1 to 4 carbon atoms, and R ₄ and R ₅ represent an alkyl group. However, l represents an integer of 0 to 4, and m represents an integer of 0 to 5. However, when l and m are each an integer of 2 or more, R ₄ and R ₅ may each independently be a different group within the same R _n . ]
However, the case where the polyarylate resin containing the repeating structural unit represented by the following formula (1) ′ is contained is excluded.

(In Formula (1) ′, R ^{11 to} R ¹⁸ and R ^{21 to} R ²⁸ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group, and X represents a single bond, an oxygen atom, A sulfur atom or a divalent group having a structure represented by the following formula (2) is shown.

In the formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group, or R ³¹ and R ³² are bonded to each other. A cycloalkylidene group or a fluorenylidene group to be formed is shown. )

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