JP2006178294A - Organic photoreceptor, processing cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoreceptor containing inorganic particles on a surface preventing lowering of image density, occurrence of fog, image blur or the like by achieving stable potential characteristics even when providing it to a contact electrification method or a color image forming apparatus, and to provide a process cartridge using the organic photoreceptor and an image forming apparatus. <P>SOLUTION: In the organic photoreceptor having a photosensitive layer on a conductive support, a surface layer of the organic photoreceptor performs surface treatment by a polymer including a methyl hydrogen siloxane unit, and in a condition of 23°C, the organic photoreceptor contains the inorganic particles in which a hydrogen generating amount measured by a gas buret method is 2.0 ml/g or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic photoreceptor used for electrophotographic image formation (hereinafter also simply referred to as a photoreceptor), and more specifically, an organic photoreceptor used for electrophotographic image formation used in the field of copying machines and printers. And a process cartridge and an image forming apparatus using the organic photoreceptor.

  Organic photoconductors have great advantages such as wide selection of materials, excellent environmental suitability and low production costs compared to inorganic photoconductors such as selenium photoconductors and amorphous silicon photoconductors. In recent years, electrophotographic photoreceptors have become the mainstream in place of inorganic photoreceptors.

  Turning to the electrophotographic process, latent image forming methods are roughly classified into analog image formation using a halogen lamp as a light source and digital image formation using an LED or laser as a light source. Recently, as a hard copy printer for a personal computer, and in an ordinary copying machine, a digital latent image forming method has been rapidly becoming mainstream because of the ease of image processing and the development of a multifunction device.

  Further, recent problems of the electrophotographic system include energy saving and response to environmental amenity.

  For example, an electrophotographic image forming apparatus generates a large amount of ozone, a nitric oxide compound, etc., which causes deterioration of an organic photoconductor (hereinafter also referred to as a photoconductor) or adversely affects the human body. The problem is well known.

  Therefore, in recent years, use of a contact charging method that does not use a corona discharger has been studied. Specifically, a voltage is applied to a magnetic brush or a conductive roller that is a charging member to bring it into contact with a photosensitive member that is a member to be charged, and the surface of the photosensitive member is charged to a predetermined potential. If such a contact charging method is used, the voltage can be lowered and the amount of ozone generated can be reduced as compared with a non-contact charging method using a corona discharger.

  However, in the contact charging method with a charging roller or the like, in addition to friction during cleaning of the photosensitive member, friction due to the contact experience member is added, and the surface wear of the photosensitive member is large, so that the potential characteristics of the photosensitive member are likely to change. The problem has occurred. In addition, nonuniform wear on the surface of the photoconductor causes cracks and contamination generated on the surface of the organic photoconductor, and electric charges concentrate on the cracks and contamination, resulting in image defects such as dielectric breakdown and black spots. It is easy for problems to occur.

  Further, as a recent problem of an electrophotographic image forming apparatus, there is a correspondence to colorization. Since printing from electronic image data using a personal computer or the like to a color image is made on a daily basis, the color printing function has become more important for electrophotographic image forming apparatuses.

  However, in an electrophotographic color image forming apparatus, toner images of four colors of B (blue), G (green), R (red), and Bk (black) are provided on each of the four photoconductors. In the color image forming apparatus in which the toner image is superimposed on the transfer medium, the difference in the wear amount of the photoconductor corresponding to B (blue), G (green), R (red), and Bk (black) As a result, the potential characteristic of each photoconductor varies, and the color reproducibility is likely to change, and the color image formation of the revolver method (a method in which four color toner images are superimposed on one photoconductor). In the apparatus, since cleaning and contact charging four times separated into B (blue), G (green), R (red), and Bk (black) are performed on the organic photoconductor, surface wear of the organic photoconductor Is larger than in the case of a monochrome image, and the potential characteristics change. A problem which the yarn kind of has occurred.

  As a common technique for solving such problems of contact charging or color images, a proposal has been made to improve the wear resistance by incorporating inorganic particles on the surface of an organic photoreceptor (Patent Document 1).

These inorganic particles are generally applied after surface treatment in order to block hydroxyl groups present on the surface. In particular, titanium oxide using methyl hydrogen polysiloxane as a surface treatment agent has a large hydroxyl-blocking effect. As a result, coating liquid dispersibility is improved, and a large amount of inorganic particles can be contained in the surface layer. Greatly improves characteristics. However, organic photoreceptors containing titanium oxide or the like surface-treated with methyl hydrogen polysiloxane have problems that potential characteristics are deteriorated, image density is lowered, and image blur is likely to occur.
JP-A-8-262755

  The present invention solves the above-mentioned problems of the prior art and achieves a stable potential characteristic even when it is provided to a contact charging system or a color image forming apparatus, thereby reducing image density, occurrence of fogging, and image blurring. It is to provide an organic photoreceptor containing inorganic particles on the surface that prevents the above, and stabilizes the characteristics of the inorganic particles surface-treated with methylhydrogenpolysiloxane, and more completely blocks the hydroxyl groups on the surface. By including inorganic particles in the surface layer, the wear resistance characteristics are improved, and at the same time, stable potential characteristics are achieved, and organic particles containing inorganic particles on the surface that prevent image density reduction, fogging, image blurring, etc. It is to provide a photoconductor, and to provide a process cartridge and an image forming apparatus using the organic photoconductor.

  Inorganic particles on the surface that improve the above-mentioned problems of the present invention, that is, improve the abrasion resistance of the organic photoreceptor and can achieve a stable potential characteristic, and prevent a decrease in image density, occurrence of fogging, image blur, etc. In order to provide an organophotoreceptor containing bismuth, the present inventors have found that it is necessary to stabilize the unstable characteristics of inorganic particles surface-treated with methylhydrogenpolysiloxane. That is, the unstable characteristics of the inorganic particles surface-treated with methyl hydrogen polysiloxane are due to the fact that the hydroxyl groups present on the surface of the inorganic particles are not sufficiently blocked even after the surface treatment. For more complete blockage, the reaction between the hydroxyl groups on the surface of the inorganic particles and methylhydrogenpolysiloxane until the amount of hydrogen generated by the gas burette method of the inorganic particles surface-treated with methylhydrogenpolysiloxane is reduced. The present invention has been completed.

That is, the present invention is achieved by having the following configuration.
(Claim 1)
In an organic photoreceptor having a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor is surface-treated with a polymer containing a methylhydrogensiloxane unit, and measured by a gas burette method at 23 ° C. An organic photoreceptor comprising inorganic particles having a generated hydrogen generation amount of 2.0 ml / g or less.
(Claim 2)
In an organic photoreceptor having a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor is subjected to a surface treatment with a polymer having a number average primary particle size of 3 to 150 nm and containing a methylhydrogensiloxane unit. An organic photoreceptor comprising inorganic particles having a hydrogen generation amount of 2.0 ml / g or less measured at 23 ° C. by a gas burette method.
(Claim 3)
The organophotoreceptor according to claim 1 or 2, wherein the polymer containing the methylhydrogensiloxane unit is methylhydrogenpolysiloxane.
(Claim 4)
The organophotoreceptor according to any one of claims 1 to 3, wherein the polymer containing a methylhydrogensiloxane unit is a copolymer of a methylhydrogensiloxane unit and another siloxane unit.
(Claim 5)
5. The organophotoreceptor according to claim 4, wherein the other siloxane unit is at least one selected from a dimethylsiloxane unit, a methylethylsiloxane unit, a methylphenylsiloxane unit, and a diethylsiloxane unit.
(Claim 6)
6. The organophotoreceptor according to claim 4, wherein the other siloxane unit is a dimethylsiloxane unit.
(Claim 7)
The organophotoreceptor according to any one of claims 1 to 6, wherein the inorganic particles are metal oxide particles in the third or fourth period of the periodic table.
(Claim 8)
The organophotoreceptor according to claim 7, wherein the metal oxide particles are one of silica, alumina, and titanium oxide.
(Claim 9)
The organic photoreceptor according to claim 1, wherein the surface layer contains an antioxidant.
(Claim 10)
In a process cartridge for use in an image forming apparatus having a charging means for charging by bringing a charging member into contact with an organic photoreceptor, the surface layer is surface-treated with a polymer containing methylhydrogensiloxane units, and a condition of 23 ° C. An organic photoreceptor containing inorganic particles having a hydrogen generation amount of 2.0 ml / g or less measured by a gas burette method, a charging means for charging by bringing a charging member into contact with the organic photoreceptor, and the organic photoreceptor An image forming apparatus that integrally supports at least one of a developing unit that visualizes the electrostatic latent image and a transfer unit that transfers a toner image visualized on the organic photoreceptor onto a transfer material. A process cartridge which is detachably attached to a main body.
(Claim 11)
In an image forming apparatus having a charging means for charging by bringing a charging member into contact with an organic photoreceptor, the surface layer of the organic photoreceptor is subjected to a surface treatment with a polymer containing a methylhydrogensiloxane unit, and a condition of 23 ° C. An image forming apparatus comprising inorganic particles having a hydrogen generation amount of 2.0 ml / g or less measured by a gas burette method.
(Claim 12)
Development in which an electrostatic latent image is formed on an organic photoreceptor, a cylindrical developing sleeve carrying a developer containing toner is disposed in contact with the organic photoreceptor, and the electrostatic latent image is visualized into a toner image. And a plurality of image forming units having transfer means for transferring a toner image formed on the organic photoreceptor to a transfer medium, and the organic photoreceptor using a toner whose coloring is changed for each of the plurality of image forming units. In an image forming apparatus for forming a color image by forming each color toner image on the surface and transferring the color toner image from the organic photoreceptor to a transfer medium, An image forming apparatus comprising inorganic particles which are subjected to surface treatment with coalescence and have a hydrogen generation amount of 2.0 ml / g or less measured at 23 ° C. by a gas burette method.

  By using the organophotoreceptor of the present invention, the potential characteristics of the organophotoreceptor containing inorganic particles on the surface are stabilized, and inorganic particles are contained on the surface that prevent reduction of image density, generation of fog, image blur, etc. An organic photoreceptor can be provided, and a process cartridge and an image forming apparatus using the organic photoreceptor can be provided.

  Hereinafter, 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, wherein the surface layer of the organic photoreceptor is surface-treated with a polymer containing a methylhydrogensiloxane unit, It is characterized by containing inorganic particles whose hydrogen generation amount measured by a gas burette method is 2.0 ml / g or less under conditions.

  The organic photoreceptor of the present invention is an organic photoreceptor having a photosensitive layer on a conductive support, wherein the surface layer of the organic photoreceptor has a number average primary particle size of 3 to 150 nm and a methylhydrogensiloxane unit. It is characterized by containing inorganic particles that are surface-treated with a polymer containing, and have a hydrogen generation amount of 2.0 ml / g or less measured at 23 ° C. by a gas burette method.

  The organophotoreceptor of the present invention has the above-described configuration, thereby stabilizing the potential characteristics of the organophotoreceptor containing inorganic particles on the surface, and preventing the decrease in image density, occurrence of fogging, image blur, etc. on the surface. An organic photoreceptor containing particles can be provided, and a good electrophotographic image can be provided over a long period of time.

The inorganic particles of the present invention are preferably metal oxides (including transition metal oxides) such as silica (SiO ₂ ), titanium oxide (TiO ₂ ), zinc oxide (ZnO), and alumina (Al ₂ O ₃ ). Among them, metal oxide particles having a third or fourth period of the periodic table are preferable, and silica, titanium oxide, and alumina are particularly preferably used.

  In the present invention, fine particles having a number average primary particle diameter of inorganic particles in the range of 3.0 to 150 nm are used. Particularly, 5 nm to 100 nm is preferable. The number average primary particle diameter is a measured value as the average diameter in the ferret direction by image analysis by magnifying fine particles 10,000 times by transmission electron microscope observation, randomly observing 100 particles as primary particles.

  Inorganic particles having a number average primary particle size of less than 3.0 nm are difficult to uniformly disperse in the surface layer, easily form agglomerated particles, and the agglomerated particles become charge traps to increase the residual potential, It tends to cause a decrease in image density, image blur, and dot image degradation. On the other hand, inorganic particles having a number average primary particle size larger than 150 nm tend to make large irregularities on the surface layer, and active gas (ozone or NOx) tends to adhere to these large irregularities, causing image blurring or dot image Prone to deterioration. In addition, inorganic particles having a number average primary particle size larger than 150 nm are likely to precipitate in the dispersion and easily generate aggregates.

  The inorganic particles of the present invention have been surface-treated with a polymer containing methylhydrogensiloxane units. A polymer containing methylhydrogensiloxane units having a molecular weight of 1000 to 20000 has a high surface treatment effect and also has a good function of preventing dielectric breakdown and black spots.

The polymer containing methylhydrogensiloxane units _{- (HSi (CH 3) O} ) - a copolymer of structural units and other structural units (that of the other siloxane units of the present invention) is preferred. 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 surface treatment of the inorganic particles can be performed by the following wet method or dry method.

  That is, an inorganic particle of titanium oxide or the like is added to a solution obtained by dissolving or suspending the polymer containing the methylhydrogensiloxane unit in an organic solvent or water, and the solution is stirred for several minutes to 1 hour. And depending on the case, after heat-processing this liquid, it passes through processes, such as filtration, and it dries, The titanium oxide particle etc. which coat | covered the surface with the polymer containing a methylhydrogensiloxane unit are obtained. A polymer containing methylhydrogensiloxane units may be added to a suspension in which titanium oxide or the like is dispersed in an organic solvent or water.

  As a dry method, a surface treatment agent (such as a solvent solution of a polymer containing a methylhydrogensiloxane unit) is sprayed on an inorganic particle such as titanium oxide while applying a high impact pressure to dry the surface, and the surface is subjected to methylhydrotherapy. Titanium oxide particles coated with a polymer containing a disiloxane unit can be obtained.

  In the present invention, the titanium oxide particles and the like coated with the polymer containing methylhydrogensiloxane units obtained as described above are further heated in a high-temperature and high-humidity environment, so that the surface of titanium oxide or the like is applied to the surface. Remaining hydroxyl groups can be reacted with active hydrogen of a polymer containing methylhydrogensiloxane units to obtain titanium oxide particles and the like with the remaining hydroxyl groups blocked on the surface, and the amount of hydrogen generation measured by the gas burette method is 2. Inorganic particles that are 0 ml / g or less can be obtained. Then, by using the inorganic particles with a small amount of hydrogen generation in the surface layer, it is possible to reduce the change in electrophotographic characteristics over time, and to obtain an organic photoreceptor having improved image blurring and generation of spots. it can.

  As the temperature and humidity conditions when heating and humidifying in the high temperature and high humidity environment, it is preferable to perform the treatment at a temperature of 40 to 90 ° C. and a humidity of 60 to 95 RH (relative humidity)% for about 3 to 200 hours.

  The amount of hydrogen generation is measured as follows.

  The amount of hydrogen gas generated was determined by the gas burette method. Disperse 2 g of surface-treated inorganic particles and 40 ml of alcohol in a three-necked flask and drop 1 ml of 10% NaOH aqueous solution dropwise in a closed system to generate hydrogen gas. Generate hydrogen per 1 g of inorganic particles at 23 ° C. The amount was calculated.

  The amount of hydrogen generation is preferably 2.0 ml / g or less at 23 ° C., more preferably 1.0 ml / g or less. The lower limit of the hydrogen generation amount is preferably less than 0.1 ml / g, but it is difficult to accurately measure the hydrogen generation amount less than 0.1 ml / g. If the amount of hydrogen generation is greater than 2.0 ml / g, the exposed area potential increases, image density decreases, and image blurring occurs.

  In the present invention, the inorganic particles may be subjected to a surface treatment with a metal oxide such as alumina, silica and zirconia before the treatment with the polymer containing the methylhydrogensiloxane unit. For example, inorganic particles subjected to silica or alumina surface treatment can be prepared as follows.

  When titanium oxide particles are used as the inorganic particles, titanium oxide particles (number average primary particle size: 50 nm) are dispersed in water at a concentration of 50 to 350 g / L to form an aqueous slurry, which is water-soluble silicate or water-soluble. Add an aluminum compound. Thereafter, alkali or acid is added for neutralization, and silica or alumina is precipitated on the surface of the titanium oxide particles. Subsequently, filtration, washing, and drying are performed to obtain the target surface-treated titanium oxide. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid or hydrochloric acid. On the other hand, when aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide.

  The ratio of the inorganic particles in the surface layer is preferably at least 5 parts by mass and 50 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 5 parts by mass, the surface layer is greatly worn, and scratches or the like are generated, so that the halftone image tends to be rough. When the amount is more than 50 parts by mass, the surface layer becomes a fragile film and cracks and the like are likely to occur.

  The surface layer according to the present invention preferably contains a charge transport material. As the charge transport material (CTM), a known hole transport property (P-type) charge transport material (CTM) is preferably used. 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 mass ratio of the binder resin and the charge transport material in the surface layer is preferably 30 to 200 parts by mass, and more preferably 50 to 150 parts by mass with respect to 100 parts by mass of the binder.

  The surface layer preferably contains an antioxidant. By including an antioxidant and inorganic particles according to the present invention in the surface layer, it is possible to prevent fluctuations in the characteristics of the surface layer during repeated use, and to prevent occurrence of fogging and a decrease in the tip concentration in the counter development method. An electrophotographic image can be provided. Typical examples of the antioxidants prevent or suppress oxidation of auto-oxidizing substances existing in or on the surface of an organic photoreceptor under conditions such as light, heat, and discharge. It is a substance with the property to do.

  The antioxidant according to the present invention has the property of preventing or suppressing the action of oxygen on auto-oxidizing substances existing in the photoreceptor or on the surface of the photoreceptor under conditions such as light, heat and discharge. It is a substance. Specifically, the following compound groups can be mentioned.

(1) Radical chain inhibitor ・ Phenol antioxidant (hindered phenol)
・ Amine antioxidants (hindered amines, diallyldiamines, diallylamines)
・ Hydroquinone antioxidant (2) Peroxide decomposer ・ Sulfur antioxidant (thioethers)
・ Phosphoric antioxidants (phosphites)
Among the above antioxidants, the radical chain inhibitor (1) is good, and a hindered phenol-based or hindered amine-based antioxidant is particularly preferable. Two or more types may be used in combination, for example, a combination of (1) a hindered phenol antioxidant and (2) a thioether antioxidant. Furthermore, the above-mentioned structural unit, for example, a hindered phenol structural unit and a hindered amine structural unit may be included in the molecule.

  Among the antioxidants, hindered phenol-based and hindered amine-based antioxidants are particularly effective in preventing fogging and image blurring at high temperatures and high humidity.

  The content of the hindered phenol-based or hindered amine-based antioxidant in the surface layer is preferably 0.01 to 20% by mass. When the content is less than 0.01% by mass, spots tend to occur. When the content exceeds 20% by mass, the charge transport ability in the surface layer decreases, the residual potential tends to increase, and the film strength decreases. Scratches are likely to occur.

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

  The hindered amine system is a compound having a bulky organic group near the N atom. The bulky organic group includes a branched alkyl group, for example, a t-butyl group is preferable. For example, compounds having an organic group represented by the following structural formula are preferred.

In the formula, R ₁₃ represents a hydrogen atom or a monovalent organic group, R ₁₄ , R ₁₅ , R ₁₆ and R ₁₇ represent an alkyl group, and R ₁₈ represents a hydrogen atom, a hydroxyl group or a monovalent organic group.

  Examples of the antioxidant having a hindered phenol partial structure include compounds described in JP-A-1-118137 (P7 to P14), but the present invention is not limited thereto.

  Examples of the antioxidant having a hindered amine partial structure include compounds described in JP-A-1-118138 (P7 to P9), but the present invention is not limited thereto.

  As an organic phosphorus compound, it is a compound represented, for example by general formula: RO-P (OR) -OR. Here, R represents a hydrogen atom, each substituted or unsubstituted alkyl group, alkenyl group or aryl group.

  The organic sulfur compound is, for example, a compound represented by the general formula: R—S—R. Here, R represents a hydrogen atom, each substituted or unsubstituted alkyl group, alkenyl group or aryl group.

  The following are examples of typical antioxidant compounds.

  Further, as the antioxidants that have been commercialized, the following compounds, for example, “Irganox 1076”, “Irganox 1010”, “Irganox 1098”, “Irganox 245”, “Irganox” as hindered phenols, are used. Knox 1330 "," Irganox 3114 "," Irganox 1076 "," 3,5-di-t-butyl-4-hydroxybiphenyl ", hindered amine series" Sanol LS2626 "," Sanol LS765 "," Sanol LS770 " , “Sanol LS744”, “Tinuvin 144”, “Tinuvin 622LD”, “Mark LA57”, “Mark LA67”, “Mark LA62”, “Mark LA68”, “Mark LA63”, and “Sumilyzer TPS” "," Sumi Iser TP-D ", and the phosphite system is" Mark 2112 "," Mark PEP-8 "," Mark PEP-24G "," Mark PEP-36 "," Mark 329K "," Mark HP-10 " Is mentioned.

  The present invention is an organic photoreceptor having a surface layer as described above. The constitution of the organic photoreceptor other than the surface layer 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 according to the present invention is not particularly limited as long as it has the surface layer described in the above-mentioned claim (1) or (2), 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 4) 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, even if the photoreceptor according to the present invention has any configuration, 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 2) 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. .

  The cylindrical conductive support means a cylindrical support that can endlessly form an image by rotating. A conductive support having a straightness of 0.1 mm or less and a deflection of 0.1 mm or less is used. preferable. 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 according to 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.

  The N-type semiconductor particles are preferably fine particles having a number average primary particle size in the range of 3.0 to 200 nm. Particularly, 5 nm to 100 nm is preferable. The number average primary particle diameter is a measured value as the average diameter in the ferret direction by image analysis by magnifying fine particles 10,000 times by transmission electron microscope observation, randomly observing 100 particles as primary particles. 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 reproducibility of dot images 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 reproducibility of 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 electron mobility is increased, the charging potential is stabilized, the residual potential is prevented from increasing, and the dot image is prevented from deteriorating.

  The N-type semiconductive particles are preferably those that have been surface-treated with a silane coupling agent or an organosilicon compound.

  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 such high-density N-type semiconductor particles in the intermediate layer, the rectification of the intermediate layer is enhanced, and the increase in residual potential and dot image degradation are effectively prevented even when the film thickness is increased. And 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.

  That is, a polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less is preferable for the intermediate layer. The heat of fusion is more preferably 0 to 30 J / g, and most preferably 0 to 20 J / g. On the other hand, if the water absorption exceeds 5% by mass, the water content in the intermediate layer increases, the rectification property of the intermediate layer decreases, black spots tend to occur, and the reproducibility of the dot image tends to deteriorate. The water absorption is more preferably 4% by mass or less.

  The heat of fusion of the resin is measured by DSC (Differential Scanning Calorimetry). However, if the same measurement value as the DSC measurement value is obtained, the DSC measurement method is not particular. The heat of fusion is determined from the endothermic peak area when the DSC temperature rises.

  On the other hand, the water absorption rate of the resin is determined by mass change by the water immersion method or by the Karl Fischer method.

  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 alcohol-soluble polyamide resins, copolymerized polyamide resins and methoxymethylated polyamide resins composed of a chemical structure with few carbon chains between amide bonds such as 6-nylon described above are known. The resin has a high water absorption rate, and the intermediate layer using such a polyamide tends to be highly environment-dependent. As a result, for example, the charging characteristics and sensitivity under high temperature and high humidity and low temperature and low humidity are likely to change. Dot image is likely to deteriorate.

  Alcohol-soluble polyamide resin improves the above-mentioned drawbacks and improves the disadvantages of conventional alcohol-soluble polyamide resins by giving the characteristics of heat of fusion 0-40 J / g and water absorption of 5% by mass or less. Even if the external environment changes or even if the organic photoreceptor is used continuously for a long time, a good electrophotographic image can be obtained.

  Hereinafter, the alcohol-soluble polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less will be described.

  The alcohol-soluble polyamide resin is preferably a polyamide resin containing a repeating unit structure having 7 to 30 carbon atoms between amide bonds in an amount of 40 to 100 mol% of the entire repeating unit structure.

  Here, a repeating unit structure having 7 to 30 carbon atoms between amide bonds will be described. The repeating unit structure means an amide bond unit forming a polyamide resin. This is because a polyamide resin (type A) formed by condensation of a compound having a repeating unit structure having both an amino group and a carboxylic acid group, and a polyamide resin (type B) formed by condensation of a diamino compound and a dicarboxylic acid compound. ) In both examples.

  That is, the repeating unit structure of type A is represented by the general formula (3), and the carbon number contained in X is the carbon number of the amide bond unit in the repeating unit structure. On the other hand, the repeating unit structure of type B is represented by the general formula (4), and the number of carbons contained in Y and the number of carbons contained in Z are respectively the number of carbons of the amide bond unit in the repeating unit structure.

In general formula (3), R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group, X is a substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, a divalent aromatic group, and these A mixed structure is shown, and l is a natural number.

In general formula (4), R ₂ and R ₃ are each hydrogen atom, a substituted or unsubstituted alkyl group, Y and Z are each substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, and a divalent group. And m and n are natural numbers.

  As described above, the repeating unit structure having 7 to 30 carbon atoms includes a substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, a divalent aromatic group, and a chemical structure having a mixed structure thereof. Among them, a chemical structure having a group containing a divalent cycloalkane is preferable.

  The polyamide resin has 7 to 30 carbon atoms between amide bonds in the repeating unit structure, preferably 9 to 25, more preferably 11 to 20. The proportion of the repeating unit structure having 7 to 30 carbon atoms between amide bonds in the entire repeating unit structure is 40 to 100 mol%, preferably 60 to 100 mol%, more preferably 80 to 100 mol%.

  When the number of carbon atoms is less than 7, the hygroscopicity of the polyamide resin is large, electrophotographic characteristics, particularly the humidity dependence of the potential during repeated use is large, and image defects such as black spots are more likely to occur. Reproducibility tends to deteriorate. If it is larger than 30, the dissolution of the polyamide resin in the coating solvent becomes worse, and it is not suitable for forming a coating film of the intermediate layer.

  Further, when the ratio of the repeating unit structure having 7 to 30 carbon atoms between amide bonds to the entire repeating unit structure is smaller than 40 mol%, the above effect is reduced.

  Preferable polyamide resin includes polyamide having a repeating unit structure represented by the following general formula (5).

In General Formula (5), Y ₁ represents a group containing a divalent alkyl-substituted cycloalkane, Z ₁ represents a methylene group, m represents 1 to 3, and n represents 3 to 20.

In the general formula (5), the group containing a divalent alkyl-substituted cycloalkane of Y ₁ preferably has the following chemical structure. That is, the polyamide resin in which Y ₁ has the following chemical structure has a remarkable effect of preventing deterioration of black spots and dot images.

In the above chemical structure, A represents a single bond and an alkylene group having 1 to 4 carbon atoms, R ₄ represents a substituent, represents an alkyl group, and p represents a natural number of 1 to 5. However, the plurality of R ₄ may be the same or different.

  Specific examples of the polyamide resin include the following examples.

  In the above specific examples, “%” in parentheses indicates the ratio (mol%) of the repeating unit structure having 7 or more carbon atoms between amide bonds in the repeating unit structure.

  Among the above specific examples, N-1 to N-4 polyamide resins having a repeating unit structure of the general formula (5) are particularly preferable.

  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 lowered, and the aggregated resin is likely to be generated in the intermediate layer, so that fog is likely to occur.

  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 produced by a general synthesis method of polyamide. However, an example of a synthesis example is given below.

Synthesis of exemplified polyamide resin (N-1) 215 parts by mass of lauryl lactam, 3-aminomethyl-3,5,5-trimethylcyclohexylamine in a polymerization kettle equipped with a stirrer, nitrogen, nitrogen introduction tube, thermometer, dehydration tube, etc. 112 parts by mass, 153 parts by mass of 1,12-dodecanedicarboxylic acid and 2 parts by mass of water were mixed and reacted for 9 hours while distilling water under heating and pressure. When the polymer was taken out and the copolymer composition was determined by C ¹³ -NMR, it coincided with the composition of N-1. The melt flow index (MFI) of the synthesized copolymer was 5 g / 10 min under the condition of (230 ° C./2.16 kg).

  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 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 reproducibility of 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 or more. The volume resistance of the intermediate layer and the protective layer 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 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 photoconductor according to 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. It is preferable that the function is separated into a charge generation layer (CGL) and a charge transport layer (CTL). 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 according to the present invention, the above-mentioned titanyl phthalocyanine adduct pigment is used as a charge generation material. it can.

  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 As described above, in the present invention, the charge transport layer is preferably composed of a plurality of charge transport layers, and the uppermost charge transport layer contains the inorganic particles according to the present invention.

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

  As the charge transport material (CTM), a known hole transport property (P-type) charge transport material (CTM) is preferably used. 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 40 μm. If the total film thickness is less than 10 μm, the concentration at the tip end tends to decrease, and if it exceeds 40 μm, the residual power tends to increase, and the sharpness tends to deteriorate. Further, the thickness of the charge transport layer serving as the surface layer is preferably 0.5 to 10 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, 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.

  Further, the coating solution for each layer is preferably filtered with a metal filter, a membrane filter or the like in order to remove foreign matters and aggregates in the coating solution before entering the coating step. For example, it is preferable to select a pleat type (HDC), a depth type (profile), a semi-depth type (profile star), etc., manufactured by Nippon Pole Co., Ltd. according to the characteristics of the coating solution and perform filtration.

  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 ride hopper type coating apparatus. For forming the surface layer according to 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.

  Next, an image forming apparatus using the contact charging method of the present invention will be described.

  FIG. 1 is a schematic cross-sectional view of an image forming apparatus 1 using a contact charging method according to the present invention. The image forming apparatus 1 includes a photosensitive cartridge 2, a developing cartridge 3, an exposure device 4 that emits a laser beam modulated based on an image signal from the outside while deflecting, a paper feeding device 5 that supplies recording paper, A transfer roller 6, a fixing device 7 and a paper discharge tray 8 are provided.

  The photoconductor cartridge 2 includes a photoconductor 21 formed by forming a thin film layer of an organic photoconductive material on the outer peripheral surface of a cylindrical body, a charging brush 22 and the like. The developing cartridge 3 includes a developing sleeve (not shown), a stirring roller, and a toner tank in which toner and a carrier are accommodated. A developing bias is applied to the developing sleeve from a developing power source (not shown). Both cartridges are closed when inserted into the image forming apparatus 1 in order to prevent problems caused by mechanical contact when the cartridge is attached to or detached from the image forming apparatus 1, and are removed from the image forming apparatus 1. A protective cover (not shown) that is sometimes opened is provided.

  Since the image forming process is well known, only a brief description will be given below. First, the surface of the photoreceptor 21 is uniformly charged with a predetermined voltage by the charging brush 22. The exposure device 4 generates a modulated laser beam (indicated by a broken arrow in the figure), deflects the laser beam by a polygon mirror (not shown), deflects and scans the surface of the photosensitive member 21, and applies it to the charged surface. The electrostatic latent images corresponding to the image information are sequentially formed. The toner in the toner tank is stirred by a stirring roller and then supplied onto the developing sleeve to form a toner image corresponding to the electrostatic latent image at a portion facing the photoreceptor 21. At the same time, residual toner existing in a portion (non-image portion) that has not been exposed on the surface of the photoconductor 21 is developed using the potential difference between the developing bias voltage applied to the developing sleeve and the surface potential of the photoconductor 21. The cartridge is recovered by electrostatic force. On the other hand, the toner image is electrostatically transferred onto the recording paper by the transfer roller 6 disposed facing the photoconductor 21. Note that the recording paper is conveyed from the paper feeding device 5 along a conveyance path indicated by a solid line arrow in the drawing. Next, the recording paper is conveyed to the fixing device 7 where the unfixed toner image is heat-fixed on the recording paper. Finally, the recording paper on which a desired image is formed is discharged from the paper discharge tray 8. By repeating the above-described series of processes, a large amount of original can be duplicated at high speed.

  The charging brush mechanically agitates the residual toner sent to the contact portion with the photoconductor by the rotation of the photoconductor and diffuses it on the surface of the photoconductor until it becomes unreadable. The charging brush electrostatically adsorbs and collects residual toner having the opposite polarity (reverse polarity) to the charging polarity of the photoconductor, and charges it to the same polarity (regular polarity) as the charging polarity of the photoconductor. Discharge onto the surface of the photoreceptor.

  FIG. 2 is a schematic cross-sectional view of a photosensitive cartridge 2 that is detachable from the image forming apparatus 1. The photosensitive member cartridge 2 includes a protective member 28 with a protective cover, a photosensitive member 21 as an image carrier, a charging brush 22 disposed around the photosensitive member 21, and a power source for applying a predetermined voltage to the charging brush 22. The connecting member 23, the pre-charge film 24, the charge leveling members (sponge-like charging members) 25 and 26, and the power source connecting member 27 are accommodated.

  The photosensitive member 21 is rotated in the direction of the arrow in the drawing by a driving device (not shown). The charging brush 22 is obtained by implanting conductive yarn made of hairy fibers on a brush support. The charging brush 22 is in contact with the surface of the photosensitive member 21 and is rotated in the same direction as the rotational direction of the photosensitive member 21 in the direction of the arrow in the drawing, that is, in the contact portion with the photosensitive member 21 by a driving device (not shown). . At the time of image formation, a voltage is applied to the charging brush 22 from a charging power source (not shown), whereby the surface of the photoreceptor 21 is uniformly charged to a predetermined polarity. On the other hand, at the time of non-image formation, a voltage having a polarity opposite to that at the time of image formation is applied to the charging brush 22 from the charging power source. The charging polarity of the toner is the same as the polarity of the charging voltage at the time of image formation. Therefore, at the time of non-image formation, the toner accumulated in the charging brush 22 can be ejected onto the photoreceptor 21 by electrostatic repulsion.

  The development pre-charge film 24 and the charge leveling members 25 and 26 are disposed for the purpose of compensating uneven charging due to the charging brush 22.

  The image forming apparatus is a monochrome laser printer, but can be similarly applied to a color laser printer or a copy. The exposure light source may also be a light source other than a laser, such as an LED light source.

  The image forming apparatus is exemplified by a cleanerless image forming apparatus, but may be an image forming apparatus provided with a dedicated cleaning device for collecting residual toner. That is, the present invention can also be applied to an image forming apparatus that is not a cleanerless type. The organic photoreceptor of the present invention may be used in a charger (corona charger or the like) in which the charging means is non-contact.

  An embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described as a full-color image forming apparatus to which the present invention is applied.

  FIG. 3 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.

  An image forming unit 10Y that forms a yellow image has a charging unit 2Y, an exposing unit 3Y, a developing unit 4Y, and a primary transfer unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A primary transfer roller 5Y and a cleaning means 6Y are provided. An image forming unit 10M that forms a magenta image includes a drum-shaped photoconductor 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 photoconductor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, 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.

In the image forming method of the present invention, when an electrostatic latent image is formed on a photoreceptor, it is preferable to perform image exposure using an exposure beam having a spot area of 2000 μm ² or less. Even when such small-diameter beam exposure is performed, the organic photoreceptor of the present invention can faithfully form an image corresponding to the spot area. A more preferable spot area is 100 to 1000 μm ² . As a result, an electrophotographic image having a gradation of not less than 800 dpi (dpi is the number of dots per 2.54 cm) can be achieved.

The spot area of the exposure beam is a light intensity distribution plane appearing on the cut surface when the exposure beam is cut along a plane perpendicular to the beam, and in a region where the light intensity is 1 / e ² or more of the maximum peak intensity. It means the corresponding area.

Examples of the light beam used include a scanning optical system using a semiconductor laser, and a solid state scanner such as an LED or a liquid crystal shutter. The light intensity distribution includes a Gaussian distribution and a Lorentz distribution, but 1 / e of each peak intensity. ^The area up to ² is the spot area.

  The endless belt-shaped intermediate transfer body unit 7 is an endless belt-shaped intermediate transfer body 70 (transfer medium) as a semiconductive endless belt-shaped second image carrier that is wound around a plurality of rollers and 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 (transfer medium) P as a transfer material (support for supporting the final fixed image: for example, plain paper, transparent sheet, etc.) housed in the paper feed cassette 20 is fed by the paper feeding means 21. Then, after passing through a plurality of intermediate rollers 22A, 22B, 22C, 22D, and a 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 collectively transfer color images. The 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, the transfer medium refers to a transfer medium for a toner image on a photosensitive member such as an intermediate transfer member or a transfer material.

  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. 4 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 sectional view of the 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.

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

  Next, the electrostatic latent image is developed with yellow toner as the first color by yellow (Y) developing means (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 organophotoreceptor of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers, but also 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 and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples. In addition, "part" in a sentence represents a mass part.

Surface treatment of inorganic particles: preparation of inorganic particles 1 5 parts of methylhydrogensiloxane are dissolved and dispersed in 100 parts of a water-methanol mixed solvent (mixing ratio 1/1), and silica (number average primary particle diameter) is mixed in the mixed solvent. (5 nm) After adding 100 parts, the mixture was stirred for 1 hour to perform methyl hydrogen siloxane surface treatment. Thereafter, the silica was filtered and dried, and then heat-treated for 36 hours under the condition of 60 ° C. and 85 RH% to obtain inorganic particles 1. The amount of hydrogen generated by the above-described measurement method of the inorganic particles 1 was 0.5 mg / g.

Preparation of inorganic particles 2 to 14 In preparation of inorganic particles 1, inorganic particles 2 were prepared in the same manner except that the types of inorganic particles, number average primary particle size, surface treatment and heat treatment conditions were changed as shown in Table 1. ~ 14 were made. For these inorganic particles, the hydrogen generation amount was measured in the same manner as the inorganic particles 1. The results are also shown in Table 1.

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; surface treatment of hexamethylsilazane)
5.6 parts Ethanol / n-propyl alcohol / THF (= 45/20/30 mass ratio) 10 parts The above components are mixed and dispersed in a batch system for 10 hours using a sand mill disperser to disperse the intermediate layer. A liquid was prepared.

Charge generation layer: CGL
Charge generation material (CGM): oxytitanyl phthalocyanine (a titanyl phthalosine pigment having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum by Cu-Kα characteristic X-ray) 24 parts polyvinyl butyral resin “S-LEC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 2-butanone / cyclohexanone = 4/1 (v / v) 300 parts The above composition is mixed, dispersed using a sand mill, and charged. A generation layer coating solution was prepared. 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 1 (CTL1)
Charge transport material (4,4′-dimethyl-4 ″-(α-phenylstyryl)
Triphenylamine) 225 parts Polycarbonate (Z300: Mitsubishi Gas Chemical Co., Ltd.) 300 parts Antioxidant (Irganox 1010: Nihon Ciba Geigy Co., Ltd.) 6 parts Dichloromethane 2000 parts Silicon oil (KF-54: Shin-Etsu Chemical Co., Ltd.) 1 part 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 18.0 μm.

Surface layer: charge transport layer 2 (CTL2)
Inorganic particles No1: (silica with an average primary particle size of 5 nm surface-treated with methylhydrogen) 60 parts Charge transport material (4,4′-dimethyl-4 ″-(α-phenylstyryl)
Triphenylamine) 150 parts Polycarbonate (Z300: Mitsubishi Gas Chemical Co., Ltd.) 300 parts Antioxidant (Exemplary Compound 1-3) 12 parts THF: Tetrahydrofuran 2800 parts Silicon oil (KF-54: Shin-Etsu Chemical Co., Ltd.) 4 parts The charge transport layer coating solution 2 was prepared by mixing, dispersing and dissolving. This coating solution is applied onto the charge transport layer 1 with a circular slide hopper coater, dried at 110 ° C. for 70 minutes to form a charge transport layer 2 having a dry film thickness of 2.0 μm, and the photoreceptor 1 is formed. Produced.

Production of Photoreceptors 2 to 14 Photoreceptor 2 was produced in the same manner as Photoreceptor 1 except that the type of inorganic particles in charge transport layer 2 (CTL2) on the surface layer was changed as shown in Table 1 in production of photoreceptor 1. ~ 14 were made.

  In Table 1, surface treatments * 1 to * 4 for inorganic particles indicate surface treatments using the following surface treatment agents. In addition, the titanium oxide of the inorganic particles 11 in Table 1 was subjected to a primary treatment of silica / alumina treatment before the treatment of * 3 methylhydrogensiloxane and dimethylsiloxane copolymer.

* 1 is methylhydrogenpolysiloxane * 2 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 1: 1)
* 3: Copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 9: 1)
* 4 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 2: 8)
Evaluation 1 (Evaluation of monochrome image)
Evaluation of potential characteristics Each of the above photoreceptors is basically mounted on a Minolta QMS (MagiColor 2300: A4 paper 16 sheets / minute printer: manufactured by Konica Minolta Business Technologies, Inc.) having the structure shown in FIGS. Evaluation was performed in a low-temperature and low-humidity environment (10 ° C., 15 RH%).

Electric potential characteristics The continuous repeated cycle of charging, exposure, and charge removal was performed 6000 times to measure the exposed portion potential.

Image Evaluation In addition, each photoconductor is attached to the EPSONLP-2400, and an original image having a solid image portion, a character image portion, and a halftone image portion with a pixel rate of 7% is printed on A4 paper, for a total of 50,000 prints. Went. Evaluation images were taken out at the start and every 10,000 copies, and the following evaluation items such as image density and image blur were evaluated. The evaluation results are shown in Table 2.

Image density Measured using a Macbeth RD-918. The relative reflection density was measured with the paper reflection density set to “0”. As the residual potential increases on multiple copies, the image density decreases. The measurement was performed on the solid black image portion after 50,000 copies.

A: Black solid image is higher than 1.2 (good)
○: Black solid image is 1.0 or more and 1.2 or less (no problem in practical use)
×: Black solid image is less than 1.0 (practical problem)
The fog density was measured by reflection density of a solid white image using RD-918 manufactured by Macbeth. The reflection density was evaluated by a relative density (the density of A4 paper not printed is 0.000). The measurement was performed on a solid white image portion after 50,000 copies.

A: Concentration is less than 0.010 (good)
○: Concentration of 0.010 or more and 0.020 or less (a level causing no practical problem)
X: Concentration is higher than 0.020 (a level that causes practical problems)
Image blur ◎: From initial to 50,000 sheets, no image blur was observed, and halftone images were clearly reproduced (very good).

  ○: The halftone image is clearly reproduced, but the image blur occurs after 30,000 sheets, but the image blur disappears when copying is stopped for a while (with practicality).

  X: Image blur occurs at less than 30,000 (practically problematic).

Dot reproducibility The dot images constituting the images were evaluated by looking through a 100x magnifier. Evaluation was made on the image of the 50,000th print.

A: The dot image is produced with an increase / decrease of less than 30% compared to the exposure spot area and is reproduced independently, and the halftone gradation is sufficiently reproduced (good).
○: The dot image is produced with an increase / decrease of 30 to 60% compared to the exposure spot area, and each is reproduced independently, and the halftone gradation is also practical (level of practicality).
X: The dot image is produced with an increase / decrease exceeding 60% compared to the exposure spot area, and the dot image disappears or is connected partially or entirely, and the halftone gradation Is insufficient (practical problem level)
Sharpness The sharpness of the image was evaluated by character collapse. Character images having different character sizes (points) were formed, and evaluated by the following criteria on a 50,000th printed character black image.

A: Characters of 4 points or less are clear and easy to read (good)
○: Characters of 6 points or less are clear and easy to read (no problem in practical use)
Δ: Characters of 8 points or less are clear and can be easily read (re-evaluation is required)
×: Some or all of the 8-point characters are illegible (practically problematic)

  From the results in Table 2, the number average primary particle size is 3 to 150 nm and surface treatment is performed with a polymer containing methylhydrogensiloxane units, and the hydrogen generation amount measured by the gas burette method at 23 ° C. Organic photoconductors (No. 1, 2, 5-9, 11-14) having a surface layer (= charge transport layer 2) containing inorganic particles of 2.0 ml / g or less are all subject to image blurring. The dot reproducibility is good, the image density and fog are evaluated to be more than the practical range, and an electrophotographic image with good sharpness is obtained. On the other hand, the photoconductor 3 containing silica having a number average primary particle size of 2 nm in the surface layer deteriorates the dispersibility of the silica, and the surface layer contains silica aggregates. Dot reproducibility has deteriorated and sharpness has deteriorated. Also, the photoreceptor 4 containing silica with a number average primary particle size of 160 nm in the surface layer has large surface layer irregularities, and active gas tends to adhere, image blurring occurs, and dot reproducibility deteriorates. Sharpness has deteriorated. Further, the surface layer photoconductor 10 containing inorganic particles with a hydrogen generation amount of 2.5 ml / g has a large deterioration in potential characteristics, a large decrease in image density, image blurring, and dot reproducibility. Deteriorated and sharpness is deteriorated.

Evaluation 2 (color image evaluation)
Four each of the photoreceptors 2, 6, 10 and 12 were prepared, and these various photoreceptors were evaluated in a low temperature and low humidity environment (10 ° C., 15 RH%). It was mounted on a commercially available full-color multifunction device 8050 (basically, a tandem-type full-color multifunction device having the configuration shown in FIG. 3: manufactured by Konica Minolta Business Technologies, Inc.) and image evaluation was performed. An original image having a white background portion, solid black portion, and solid image portion of red, green, and blue, a character image portion, and a halftone image portion was copied and evaluated on A4 paper. Specifically, a copy image for evaluation was taken out at the start and every 10,000 sheets, and a total of 50,000 sheets were printed and evaluated. Evaluation items and evaluation criteria are shown below.

Evaluation condition Photoconductor linear velocity: 220 mm / sec
Line speed of developing sleeve: 350 mm / sec
Development: Yellow toner, magenta toner, cyan toner and black toner used for each developing means (4Y, 4M, 4C, 4Br) have an average particle diameter of 6.5 μm, 0.3 μm hydrophobic titanium oxide and 15 nm respectively. A two-component developer using a polymerized toner containing a hydrophobic silica external additive was used. Reversal development method (1) Image evaluation Image blur ◎: From initial to 50,000 sheets, no image blur was observed and a halftone image was clearly reproduced (very good).
○: The halftone image is clearly reproduced, but image blurring occurs after 30,000 sheets, but there is no image blurring for copying for a while (with practicality).
X: Image blur occurs at less than 30,000 (practically problematic).

Image density A density meter “RD-918” (manufactured by Macbeth Co.) was used for the 50,000th sheet, and the image density was measured at a relative density with the reflection density of A4 paper set to 0.000.
A: Solid black image is 1.30 or more (very good)
○: Solid black image is 1.00 or more (a level that causes no problem in practical use)
X: Solid black image less than 1.00 (practical problem)
For the 50,000th fog, a densitometer “RD-918” (manufactured by Macbeth Co.) was used, and the fog density was measured at a relative density where the reflection density of A4 paper was 0.000.
A: Less than 0.010 (very good)
○: 0.010 or more and less than 0.020 (a level that causes no problem in practice)
×: 0.020 or more (problematic problems)
(Evaluation criteria for color spot image defects)
Regarding the color spots, the periodicity coincided with the period of the photoreceptor, and it was determined how many color spots per A4 size were visible. Evaluation was made on the 50,000th sheet.
A: Color spot frequency of 0.4 mm or more Frequency: All 3 copies / A4 or less (good)
◯: Color spot frequency of 0.4 mm or more Frequency: 4 / A4 or more, 10 / A4 or less occurs (no problem in practical use)
×: Color spot frequency of 0.4 mm or more Frequency: 11 / A4 or more occurs (practically problematic)
Color reproducibility The color of the solid image portion of the secondary color (red, blue, green) in each of the Y, M, and C toners of the first image and the 100th image is measured by “Macbeth Color-Eye 7000”, and CMC The color difference between the first and 100th sheets of each solid image was calculated using the (2: 1) color difference formula.

A: Color difference is 3 or less (good)
×: Color difference is greater than 3 (practical problem and impractical)
The results are shown in Table 3.

  As is apparent from Table 3, in the image evaluation of the full-color multifunction device 8050, the surface layer was surface-treated with a polymer containing methylhydrogensiloxane units, and hydrogen generation was measured by a gas burette method at 23 ° C. The organic photoreceptors 2, 6, and 12 containing inorganic particles having an amount of 2.0 ml / g or less gave good results in all evaluations such as image density, fog, image blur, color spot, and color reproducibility. However, in the organic photoreceptor 10 containing inorganic particles having a hydrogen generation amount of 2.5 ml / g, the image density is lowered, color spots are frequently generated, image blur is generated, and color reproducibility is also improved. It has deteriorated.

1 is a schematic cross-sectional view of an image forming apparatus using a contact charging system according to the present invention. 2 is a schematic cross-sectional view of a photosensitive cartridge that is detachable from an image forming apparatus. FIG. 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 2 Photoconductor cartridge 3 Developer cartridge 4 Exposure apparatus 5 Paper feeder 6 Transfer roller 7 Fixing device 8 Paper discharge tray 21 Photoconductor 22 Charging brush 23, 27 Power supply connection member 24 Pre-charge film 25, 26 Charging Element

Claims (12)

In an organic photoreceptor having a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor is surface-treated with a polymer containing a methylhydrogensiloxane unit, and measured by a gas burette method at 23 ° C. An organic photoreceptor comprising inorganic particles having a generated hydrogen generation amount of 2.0 ml / g or less. In an organic photoreceptor having a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor is surface-treated with a polymer having a number average primary particle size of 3 to 150 nm and containing a methylhydrogensiloxane unit. An organic photoreceptor comprising inorganic particles having a hydrogen generation amount of 2.0 ml / g or less measured at 23 ° C. by a gas burette method. The organophotoreceptor according to claim 1 or 2, wherein the polymer containing the methylhydrogensiloxane unit is methylhydrogenpolysiloxane. The organophotoreceptor according to any one of claims 1 to 3, wherein the polymer containing a methylhydrogensiloxane unit is a copolymer of a methylhydrogensiloxane unit and another siloxane unit. 5. The organophotoreceptor according to claim 4, wherein the other siloxane unit is at least one selected from a dimethylsiloxane unit, a methylethylsiloxane unit, a methylphenylsiloxane unit, and a diethylsiloxane unit. 6. The organophotoreceptor according to claim 4, wherein the other siloxane unit is a dimethylsiloxane unit. The organophotoreceptor according to any one of claims 1 to 6, wherein the inorganic particles are metal oxide particles in the third or fourth period of the periodic table. 8. The organophotoreceptor according to claim 7, wherein the metal oxide particles are one of silica, alumina, and titanium oxide. The organic photoreceptor according to claim 1, wherein the surface layer contains an antioxidant. In a process cartridge for use in an image forming apparatus having a charging means for charging by bringing a charging member into contact with an organic photoreceptor, the surface layer is surface-treated with a polymer containing methylhydrogensiloxane units, and a condition of 23 ° C. An organic photoreceptor containing inorganic particles having a hydrogen generation amount of 2.0 ml / g or less measured by a gas burette method, a charging means for charging by bringing a charging member into contact with the organic photoreceptor, and the organic photoreceptor An image forming apparatus that integrally supports at least one of a developing unit that visualizes the electrostatic latent image and a transfer unit that transfers a toner image visualized on the organic photoreceptor onto a transfer material. A process cartridge which is detachably attached to a main body. In an image forming apparatus having a charging means for charging by bringing a charging member into contact with an organic photoreceptor, the surface layer of the organic photoreceptor is subjected to a surface treatment with a polymer containing a methylhydrogensiloxane unit, and a condition of 23 ° C. An image forming apparatus comprising inorganic particles whose hydrogen generation amount measured by a gas burette method is 2.0 ml / g or less. Development in which an electrostatic latent image is formed on an organic photoreceptor, a cylindrical developing sleeve carrying a developer containing toner is disposed in contact with the organic photoreceptor, and the electrostatic latent image is visualized into a toner image. And a plurality of image forming units having transfer means for transferring a toner image formed on the organic photoreceptor to a transfer medium, and the organic photoreceptor using a toner whose coloring is changed for each of the plurality of image forming units. In an image forming apparatus for forming a color image by forming each color toner image on the surface and transferring the color toner image from the organic photoconductor to a transfer medium, the surface layer of the organic photoconductor includes a multi-layer containing methylhydrogensiloxane units. An image forming apparatus comprising inorganic particles which are subjected to surface treatment with coalescence and have a hydrogen generation amount of 2.0 ml / g or less measured at 23 ° C. by a gas burette method.

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