JP2012189976A - Organic photoreceptor, image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic photoreceptor, and an image forming apparatus and an image forming method employing a contact charging system, which can solve problems associated with repeated use in the image forming method employing the contact charging system, that is, to improve wear resistance characteristics, to avoid generation of a dash mark, generation of a transfer void, or the like, to prevent degradation in electrophotographic characteristics (such as increase in a residual potential or generation of an image memory phenomenon), and to stably carry out formation of a favorable electrophotographic image for a long period of time.SOLUTION: The organic photoreceptor includes a photosensitive layer and a protective layer on a conductive support. The protective layer is a resin layer formed of a composition containing a metal oxide subjected to a surface treatment with a compound having a radical polymerizable functional group, a polymerizable compound and carbon nanotube.

Description

  The present invention relates to an organic photoreceptor (hereinafter also simply referred to as a photoreceptor) used for electrophotographic image formation, and an image forming apparatus using the organic photoreceptor, and more specifically, used in the fields of copying machines and printers. The present invention relates to an organic photoreceptor used for electrophotographic image formation, an image forming apparatus using the organic photoreceptor, and an image forming method.

  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.

  On the other hand, in the image forming method based on the Carlson method, a charged, electrostatic latent image is formed on an organic photoreceptor, a toner image is formed, the toner image is transferred to a transfer paper, and this is fixed and a final image is formed. Is formed.

  A corona discharger is the best known charging member that has been used as a member of the charging means. The corona discharger has an advantage that stable charging can be performed. However, since a high voltage must be applied to the corona discharger, a large amount of ionized oxygen, ozone, moisture, nitric oxide compound, etc. is generated, which causes deterioration of the organic photoreceptor (hereinafter also referred to as a photoreceptor). Or have problems such as adversely affecting the human body.

  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 as a charging member to bring it into contact with a photosensitive member as 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.

In the contact charging method, a direct current voltage or a direct current voltage superimposed on an alternating current is applied to a charging member having a resistance of about 10 ² to 10 ¹⁰ Ω · cm, and the photosensitive member is pressed and brought into contact with the photosensitive member to give an electric charge. Is the method. Since this charging method is performed by discharging from the charging member to the member to be charged in accordance with Paschen's law, charging is started by applying a voltage equal to or higher than a certain threshold value. In this contact charging method, compared with the corona charging method, the voltage applied to the charging member is lowered, and the generation amount of ozone and nitrogen oxides is reduced.

  On the other hand, digitalization has progressed in recent image forming methods, and an image forming method using laser light as an exposure light source is often used for forming an electrostatic latent image on an organic photoreceptor.

  However, the organic photoreceptor has a problem that the surface is easily worn by friction with the contact charging member. In order to prevent wear deterioration of the surface layer, the charge transport layer binder is known as a polycarbonate resin having high wear resistance, that is, a polycarbonate resin having a central carbon atom as a cyclohexylene group (polycarbonate Z (also simply referred to as BPZ)). Has been proposed (Patent Document 1).

  However, when the wear resistance of the organophotoreceptor is improved using the binder, the wear resistance is improved. However, an inorganic external additive such as silica in the developer is pressed against the surface of the organophotoreceptor by pressing the contact charging member. The surface of the organic photoreceptor is easily contaminated with these external additive components, and as a result, a dash mark (small comet-like streak image) is likely to occur.

  In order to solve the above-mentioned problems of wear resistance and contamination of the photoreceptor surface, a protective layer of an acrylic cross-linked cured resin is provided on the surface layer of the photoreceptor, and a fluorine compound is contained in the protective layer. Thus, a photoconductor having a large contact angle on the surface has been proposed (Patent Document 2).

  However, a photoconductor provided with a protective layer of an acrylic cross-linked cured resin described in Patent Document 2 and having a large contact angle on the surface has improved wear resistance and dash marks, and further during toner transfer. Although the improvement of omission has been reported, the electrophotographic characteristics due to the installation of the protective layer deteriorated, causing new problems such as an increase in residual potential and the occurrence of image memory (a phenomenon in which the image of the previous page remains). ing. Further, in the protective layer of the photoreceptor described in Patent Document 2, the wear resistance characteristics of the photoreceptor by the contact charging method are not sufficiently improved.

  Moreover, in order to improve the abrasion resistance property of a protective layer, the report which contains an inorganic filler like a carbon nanotube in the protective layer of curable resin is also seen (patent document 3). However, from the description of such a protective layer, the protective layer can improve the wear resistance of the protective layer, improve the dash mark and toner transfer omission, and further prevent the residual potential from increasing and generating image memory. It is not recognized that this is achieved.

Japanese Patent Application Laid-Open No. 60-172044 JP-A-8-179541 JP 2010-145891 A

  The present invention provides an organic photoreceptor, an image forming apparatus, and an image forming method capable of forming a stable image over a long period of time even when using a charging method with low generation amount of ozone and nitrogen oxide and low power. Is to provide.

  Another object of the present invention is to improve the problems associated with repeated use in the contact charging type image forming system, that is, improve the wear resistance, improve the generation of dash marks and the occurrence of transfer dropout, etc. (Organic photoreceptor and contact charging type image forming apparatus capable of preventing long-term stable and good electrophotographic image formation by preventing deterioration of the residual potential (increase in residual potential, generation of image memory, etc.), An image forming method is provided.

  In order to solve the above-mentioned problems, the present inventors have studied in detail the requirements of an organic photoreceptor suitable for the contact charging method. As a result, the above-described improvement in wear resistance, generation of dash marks, occurrence of transfer dropout, etc. In order to prevent the deterioration of electrophotographic characteristics and increase the electrophotographic characteristics (increased residual potential and generation of image memory, etc.) and obtain good electrophotographic image formation stably over the long term, a protective layer is applied to the organic photoreceptor. In addition, the inventors have found that it is effective to use a protective layer of an acrylic cross-linked cured resin with improved deterioration of electrophotographic characteristics, and completed the present invention. That is, the object of the present invention can be achieved by having the following configuration.

  1. An organic photoreceptor having a photosensitive layer and a protective layer on a conductive support, wherein the protective layer is a composition containing a metal oxide, a polymerizable compound, and carbon nanotubes that are surface-treated with a compound having a radical polymerizable functional group. An organic photoreceptor, which is a formed resin layer.

  2. 2. The organophotoreceptor according to 1 above, wherein the carbon nanotube is an armchair single-walled carbon nanotube.

  3. 3. The organophotoreceptor according to 1 or 2 above, wherein the radical polymerizable functional group is an acryloyl group or a methacryloyl group.

  4). 4. The organophotoreceptor according to any one of items 1 to 3, wherein the polymerizable compound is an acrylic monomer or oligomer having an acryloyl group or a methacryloyl group.

  5). 5. An image forming apparatus having a charging means for charging by bringing a charging member into contact with the organic photoconductor, wherein the organic photoconductor is the organic photoconductor described in any one of 1 to 4 above.

  6). 6. An image forming method comprising forming an electrophotographic image using the image forming apparatus described in 5 above.

  By using the organophotoreceptor of the present invention, it is possible to prevent deterioration of wear resistance and image defects such as dash marks and transfer defects that are likely to occur in the contact charging method, and no increase in residual potential or image memory occurs. In addition, an organic photoreceptor having good electrophotographic characteristics can be provided, and a good electrophotographic image can be provided stably.

1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention. It is sectional drawing which showed the structure of the charging roller.

  Hereinafter, the present invention will be described in detail.

  The organophotoreceptor of the present invention is an organophotoreceptor having a photosensitive layer and a protective layer on a conductive support, and the protective layer is a metal oxide or polymerizable compound whose surface is treated with a compound having a radical polymerizable functional group. And a resin layer formed from a composition containing carbon nanotubes.

  The organophotoreceptor of the present invention has the above-described configuration, thereby preventing image defects such as deterioration of wear resistance and dash marks and transfer voids, and providing an organophotoreceptor having good electrophotographic characteristics, which is stable. Thus, a good electrophotographic image can be provided.

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

[Metal oxide particles used in the present invention]
The metal oxide particles according to the present invention may be any metal oxide particles including transition metals. For example, silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide), oxidation Tantalum, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titania (titanium oxide), niobium oxide, molybdenum oxide, vanadium oxide, etc. In particular, titanium oxide, alumina, and tin oxide particles are preferable.

  The method for producing metal oxide particles according to the present invention is not particularly limited, and examples thereof include an indirect method (French method), a direct method (American method), and a plasma method.

  The metal oxide particles used in the present invention are fine particles having crystal habits in which the metal oxide particles produced by the plasma method are smaller in average particle size than other production methods and have a relatively uniform particle shape. preferable.

  Examples of a method for generating metal oxide particles by a plasma method include a direct current plasma arc method, a high frequency plasma method, and a plasma jet method.

  In the DC plasma arc method, a metal raw material is used as a consumption anode electrode. Then, a plasma flame is generated from the cathode electrode. Then, it is desirable to obtain metal oxide particles by heating and evaporating the metal material on the anode side and oxidizing and cooling the vapor of the metal material.

  The high frequency plasma method uses thermal plasma generated when a gas is heated by high frequency induction discharge under atmospheric pressure. Among these, in the plasma evaporation method, solid particles are injected into the center of the inert gas plasma, evaporated while passing through the plasma, and ultrafine particles can be generated by rapidly cooling and condensing the high-temperature vapor.

  In the plasma method, argon plasma, hydrogen plasma, etc. can be obtained by arc discharge in the inert gas argon and diatomic molecular hydrogen or nitrogen or oxygen atmosphere. In particular, diatomic molecular gas is thermally dissociated. The generated hydrogen (nitrogen, oxygen) plasma is much more reactive than the molecular gas, so it is also called reactive arc plasma to distinguish it from inert gas plasma. Among these, the oxygen plasma method is effective as a method for generating metal oxide particles.

  The number average primary particle size of the metal oxide particles according to the present invention is preferably in the range of 1 to 300 nm. Especially preferably, it is 3-100 nm.

  The number average primary particle size of the metal oxide particles is a photographic image (excluding aggregated particles) taken with a scanning electron microscope (manufactured by JEOL Ltd.) with a magnification of 10000 times, and 300 particles randomly taken by a scanner. A) automatic image processing analyzer LUZEX AP (Nireco Corp.) software version Ver. The number average primary particle size was calculated using 1.32.

(Metal oxide surface-treated with a compound having a radical polymerizable functional group)
The metal oxide particles surface-treated with the compound having a radical polymerizable functional group of the present invention can be obtained by surface treatment with a compound having a radical polymerizable functional group.

  Next, a compound having a radical polymerizable functional group used for the surface treatment of metal oxide particles will be described.

  The compound having a radical polymerizable functional group used for the surface treatment of the metal oxide particles may be a compound having a radical polymerizable functional group reactive with a hydroxyl group or the like present on the surface of the metal oxide particles. Examples of such reactive surface treatment agents include the compounds described below.

_{S-1 CH 2 = CHSi (} CH 3) (OCH 3) 2
_{S-2 CH 2 = CHSi (} OCH 3) 3
S-3 CH ₂ = CHSiCl _{3
S-4 CH 2 = CHCOO (} CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5 CH 2 = CHCOO (} CH 2) 2 Si (OCH 3) 3
_{S-6 CH 2 = CHCOO (} CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-7 CH 2 = CHCOO (} CH 2) 3 Si (OCH 3) 3
_{S-8 CH 2 = CHCOO (} CH 2) 2 Si (CH 3) Cl 2
_{S-9 CH 2 = CHCOO (} CH 2) 2 SiCl 3
_{S-10 CH 2 = CHCOO (} CH 2) 3 Si (CH 3) Cl 2
S-11 CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12 CH 2 = C (} CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13 CH 2 = C (} CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14 CH 2 = C (} CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15 CH 2 = C (} CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16 CH 2 = C (} CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17 CH 2 = C (} CH 3) COO (CH 2) 2 SiCl 3
_{S-18 CH 2 = C (} CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19 CH 2 = C (} CH 3) COO (CH 2) 3 SiCl 3
_{S-20 CH 2 = CHSi (} C 2 H 5) (OCH 3) 2
S-21 CH ₂ ═C (CH ₃ ) Si (OCH ₃ ) _{3
S-22 CH 2 = C (} CH 3) Si (OC 2 H 5) 3
_{S-23 CH 2 = CHSi (} OCH 3) 3
_{S-24 CH 2 = C (} CH 3) Si (CH 3) (OCH 3) 2
_{S-25 CH 2 = CHSi (} CH 3) Cl 2
_{S-26 CH 2 = CHCOOSi (} OCH 3) 3
_{S-27 CH 2 = CHCOOSi (} OC 2 H 5) 3
_{S-28 CH 2 = C (} CH 3) COOSi (OCH 3) 3
_{S-29 CH 2 = C (} CH 3) COOSi (OC 2 H 5) 3
_{S-30 CH 2 = C (} CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3

  In the compound having a radical polymerizable functional group, the radical polymerizable functional group is preferably an acryloyl group or a methacryloyl group.

  The amount of the compound having a radical polymerizable functional group to be treated with the metal oxide particles is 0.1 to 200 parts by mass of the compound having a radical polymerizable functional group with respect to 100 parts by mass of the metal oxide particles before the treatment. preferable.

[Production of metal oxide particles surface-treated with a compound having a radical polymerizable functional group]
Hereinafter, a method for producing metal oxide particles surface-treated with a compound having a radical polymerizable functional group will be described by taking titanium oxide particles as an example.

  The titanium oxide particles surface-treated with the compound having a radically polymerizable functional group according to the present invention are surface-treated with a silane compound having the radically polymerizable functional group (the above exemplified compound) or the like. Can be obtained. In performing the surface coating treatment, a wet media dispersion type apparatus is used by using 0.1 to 200 parts by mass of a silane compound as a surface treatment agent and 50 to 5000 parts by mass of a solvent with respect to 100 parts by mass of titanium oxide particles before the treatment. It is preferable to use and process.

  Hereinafter, a surface treatment method for producing titanium oxide particles that are surface-coated with a silane compound having a radically polymerizable functional group that is uniform and more finely described will be described.

  That is, a slurry (a suspension of solid particles) containing titanium oxide particles and a surface treatment agent of a silane compound having a radical polymerizable functional group is wet-pulverized to simultaneously refine the titanium oxide particles and Surface treatment proceeds. Thereafter, since the solvent is removed to form powder, titanium oxide particles that are surface-treated with a uniform and finer silane compound can be obtained.

  The wet media dispersion type apparatus, which is a surface treatment apparatus used in the present invention, is a metal oxide particle by filling beads in a container as a medium and rotating a stirring disk mounted perpendicularly to a rotation axis at high speed. It is a device having a step of crushing and pulverizing and dispersing the aggregated particles of the metal oxide, and the constitution thereof should be a type in which the metal oxide particles can be sufficiently dispersed and surface-treated when the surface treatment is performed on the metal oxide particles. For example, various types such as a vertical type, a horizontal type, a continuous type, and a batch type can be adopted. Specifically, a sand mill, ultra visco mill, pearl mill, glen mill, dyno mill, agitator mill, dynamic mill and the like can be used. These dispersion-type devices are pulverized and dispersed by impact crushing, friction, shearing, shear stress, etc., using a grinding medium (media) such as balls and beads.

  As the beads used in the wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone and the like can be used, and those made of zirconia or zircon are particularly preferable. Further, as the size of the beads, those having a diameter of about 1 to 2 mm are usually used, but in the present invention, those having a diameter of about 0.1 to 1.0 mm are preferably used.

  Various materials such as stainless steel, nylon and ceramic can be used for the disk and container inner wall used in the wet media dispersion type apparatus. In the present invention, the disk and container inner wall made of ceramic such as zirconia or silicon carbide are particularly used. Is preferred.

  Titanium oxide particles surface-treated with a surface treatment agent can be obtained by the wet treatment as described above.

  The titanium oxide particles have been described above, but metal oxide particles such as alumina, zinc oxide, tin oxide, and silica also have hydroxyl groups on the surface in the same manner as titanium oxide. The metal oxide particles surface-treated with can be obtained.

(Polymerizable compound)
Next, the polymerizable compound used in the present invention will be described.

  The polymerizable compound is preferably a monomer that is polymerized (cured) by irradiation with active rays such as ultraviolet rays and electron beams and becomes a resin generally used as a binder resin for a photoreceptor, such as polystyrene and polyacrylate. In particular, styrene monomers, acrylic monomers, methacrylic monomers, vinyl toluene monomers, vinyl acetate monomers, and N-vinyl pyrrolidone monomers are preferable.

Among these, radically polymerizable compounds having an acryloyl group (CH ₂ ═CHCO—) or a methacryloyl group (CH ₂ ═CCH ₃ CO—) are particularly preferable because they can be cured with a small amount of light or in a short time.

  In the present invention, these radically polymerizable compounds may be used alone or in combination.

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

  However, in the above, R is shown below.

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

  The radical polymerizable compound is preferably a compound having a functional group (reactive group) of 3 or more. Further, the radical polymerizable compound may be used in combination of two or more kinds of compounds, but in this case as well, it is preferable to use 50% by mass or more of the radical polymerizable compound having 3 or more functional groups. The curable reactive group equivalent, that is, “curable functional group molecular weight / number of functional groups” is preferably 1000 or less, more preferably 500 or less. This increases the crosslink density and improves wear resistance.

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

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

  The photoinitiator used preferably below is illustrated.

  Examples of α-aminoacetophenone series

  Examples of α-hydroxyacetophenone compounds

  Examples of acylphosphine oxide compounds

  Examples of other radical polymerization initiators

  In the present invention, these polymerization initiators are mixed with a composition containing treated metal oxide particles and, if necessary, a radical polymerizable compound to prepare a coating solution for the surface layer, and the coating solution Is coated on the photosensitive layer and dried by heating to form a surface layer according to the present invention. As the thermal polymerization initiator, the above-mentioned other radical polymerization initiators can be used.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.1-20 mass parts with respect to 100 mass parts of an acryl-type compound, Preferably it is 0.5-10 mass parts.

〔carbon nanotube〕
The protective layer according to the present invention also contains carbon nanotubes.

  A carbon nanotube is a carbon-based fiber material having a shape in which a graphite-like carbon atomic plane (graphene sheet) having a thickness of several atomic layers is wound in a cylindrical shape. Single-walled nanotubes (SWCNT) and multi-layers are formed from the number of peripheral walls. They are roughly classified into nanotubes (MWCNT), and are divided into chiral (helical), zigzag and armchair types according to the difference in the structure of the graphene sheet, and various types are known.

  As the carbon nanotubes applied to the protective layer according to the present invention, any type of carbon nanotubes can be used, and a mixture of these various carbon nanotubes may be used, but the conductivity is excellent. Single-walled carbon nanotubes are preferable, and metallic armchair-type single-walled carbon nanotubes excellent in conductivity and translucency are more preferable.

The shape of the carbon nanotube according to the present invention is preferably a single-walled carbon nanotube having a large aspect ratio (= length / diameter), that is, a thin and long carbon nanotube, in order to form a long conductive path with one carbon nanotube. . For example, an aspect ratio of 10 ² or more, and preferably 10 ³ or more carbon nanotubes. The average length of the carbon nanotubes is preferably 3 μm or more, more preferably 3 to 500 μm, and particularly preferably 3 to 300 μm. In addition, the relative standard deviation of the length is preferably 40% or less. Moreover, it is preferable that an average diameter is smaller than 100 nm, 1-50 nm is preferable and it is more preferable that it is 1-30 nm. In addition, the relative standard deviation of the diameter is preferably 20% or less.

  The production method of the carbon nanotube used in the present invention is not particularly limited, and catalytic hydrogen reduction of carbon dioxide, arc discharge method, laser evaporation method, CVD method, vapor phase growth method, high temperature and high pressure of carbon monoxide. Well-known means such as HiPco method in which the reaction is carried out together with an iron catalyst and grown in the gas phase can be used. Moreover, in order to remove residues such as by-products and catalytic metals, carbon nanotubes that have been further purified by various purification methods such as washing methods, centrifugal separation methods, filtration methods, oxidation methods, chromatographic methods, etc. Is more preferable because various functions can be sufficiently expressed.

  The protective layer according to the present invention is a composition in which a metal oxide surface-treated with a compound having a radical polymerizable functional group, a polymerizable compound, a carbon nanotube, a polymerization initiator and the like are mixed in a solvent, The composition can be applied on a photosensitive layer described later, and then dried and cured to form a resin layer as a protective layer. The resin layer of the protective layer is protected by a mixture of polymerization reactions such as reactions between radically polymerizable functional groups of metal oxides, reactions between radically polymerizable functional groups and polymerizable compounds, and reactions between polymerizable compounds. A resin layer is formed.

  The composition ratio of the metal oxide surface-treated with the compound having a radical polymerizable functional group, the polymerizable compound, and the carbon nanotube is preferably 50 to 150: 100: 1 to 10 in terms of mass ratio.

  As described above, by incorporating carbon nanotubes into the curable protective layer according to the present invention, trapping of charge carriers in the protective layer can be prevented, and an increase in residual potential and generation of image memory can be prevented. Since accumulation of electric charges in the layer is prevented, the transferability of the toner is improved, and an improvement effect has also been confirmed in the transfer omission.

  The protective layer of the present invention can further contain various charge transport materials and antioxidants, and various lubricant particles can be added. For example, fluorine atom-containing resin particles can be added. Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluorochloroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these One or two or more types are preferably selected from the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

  Solvents for forming the protective layer include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, acetic acid. Examples thereof include, but are not limited to, ethyl, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine and diethylamine.

  The protective layer of the present invention is preferably subjected to reaction by irradiation with actinic radiation after natural drying or heat drying after coating.

  As the coating method, known methods such as dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method and the like can be used.

  The photoreceptor of the present invention is capable of generating a cured resin by irradiating actinic rays on the coating to generate radicals and polymerizing, and curing by forming a cross-linking bond between molecules and within the molecule. preferable. As the active ray, ultraviolet rays and electron beams are particularly preferable.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² . The power of the lamp is preferably 0.1 kW to 5 kW, particularly preferably 0.5 kW to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.5 to 10 Mrad.

  The irradiation time for obtaining the necessary irradiation amount of active rays is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of work efficiency.

  As the actinic radiation, ultraviolet rays are easy to use and are particularly preferable.

  The photoreceptor of the present invention can be dried before and after irradiating active rays and during irradiation with active rays, and the timing of drying can be appropriately selected by combining them.

  Drying conditions can be appropriately selected depending on the type of solvent, film thickness, and the like. The drying temperature is preferably room temperature to 180 ° C, particularly preferably 80 ° C to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

  The thickness of the protective layer is preferably 0.2 to 10 μm, more preferably 0.5 to 6 μm.

[Organic photoconductor composition]
Below, the structure of organic photoreceptors other than the said protective layer is described.

  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 organic photoreceptor of the present invention is obtained by sequentially laminating at least a photosensitive layer and a surface layer as described above on a conductive support. Specifically, the layer structure as shown below is exemplified. Can do.

  1) A layer structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated as an intermediate layer and a photosensitive layer on a conductive support.

  2) A layer structure in which an intermediate layer, a single layer containing a charge transport material and a charge generation material as a photosensitive layer, and a protective layer are sequentially laminated on a conductive support.

  The layer structure of the organic photoreceptor of the present invention will be described focusing on the above 1).

(Conductive support)
The support used in the present invention may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or a sheet, aluminum or copper Metal foils such as those laminated on plastic films, aluminum, indium oxide and tin oxide deposited on plastic films, metals with conductive layers applied alone or with a binder resin, plastic films and For example, paper.

(Middle layer)
In the present invention, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive layer and the photosensitive layer. Considering various types of failure prevention, it can be said that providing an intermediate layer is a preferable mode.

  The intermediate layer can be formed by dip coating or the like by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane and gelatin in a known solvent. Of these, an alcohol-soluble polyamide resin is preferred.

  Various conductive fine particles and metal oxide particles can be contained for the purpose of adjusting the resistance of the intermediate layer. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used.

  These metal oxide particles may be used alone or in combination. When two or more types are mixed, it may take the form of a solid solution or fusion. The average particle size of such metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  As the solvent used for the intermediate layer, a solvent in which inorganic particles are well dispersed and the polyamide resin is dissolved is preferable. Specifically, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol and the like are excellent in solubility and coating performance of the polyamide resin. In addition, examples of co-solvents that can be used in combination with the above-described solvent to obtain favorable effects in order to improve storage stability and particle dispersibility include methanol, benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The density | concentration of binder resin is suitably selected according to the film thickness and production rate of an intermediate | middle layer.

  When the inorganic particles are dispersed, the mixing ratio of the inorganic particles to the binder resin at the time is preferably 20 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  As a means for dispersing the inorganic particles, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

  The method for drying the intermediate layer can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  The thickness of the intermediate layer is preferably from 0.1 to 15 μm, more preferably from 0.3 to 10 μm.

(Charge generation layer)
The charge generation layer used in the present invention preferably contains a charge generation material and a binder resin, and is formed by dispersing and coating the charge generation material in a binder resin solution.

  Examples of the charge generation material include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and phthalocyanine pigments. It is not something. These charge generating substances can be used alone or in a form dispersed in a known resin.

  As the binder resin of the charge generation layer, a known resin can be used, for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, Polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (eg, vinyl chloride-vinyl acetate copolymer resins, chlorides) Vinyl-vinyl acetate-maleic anhydride copolymer resin) and poly-vinylcarbazole resin, but are not limited thereto.

  The charge generation layer is formed by dispersing a charge generation material in a solution in which a binder resin is dissolved in a solvent using a disperser to prepare a coating solution, and applying the coating solution to a certain film thickness using a coating device. It is preferable to prepare the film by drying.

  Solvents for dissolving and coating the binder resin used in the charge generation layer include, for example, toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, Examples include butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine, but are not limited thereto.

  As a means for dispersing the charge generating material, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

  The mixing ratio of the charge generating material to the binder resin is preferably 1 to 600 parts by weight, more preferably 50 to 500 parts by weight based on 100 parts by weight of the binder resin. The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm. It should be noted that the coating solution for the charge generation layer can prevent the occurrence of image defects by filtering foreign matter and aggregates before coating. The pigment can also be formed by vacuum deposition.

(Charge transport layer)
The charge transport layer used in the photoreceptor of the present invention contains a charge transport material (CTM) and a binder resin, and is formed by dissolving and coating the charge transport material in a binder resin solution.

  Examples of charge transport materials include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds Oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1- Two or more kinds of vinylpyrene, poly-9-vinylanthracene, triphenylamine derivatives and the like may be mixed and used.

  A known resin can be used as the binder resin for the charge transport layer, and polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic ester resin, and styrene-methacrylic acid. Examples include ester copolymer resins, and polycarbonate is preferred. Further, BPA, BPZ, dimethyl BPA, BPA-dimethyl BPA copolymer and the like are preferable in terms of crack resistance, wear resistance, and charging characteristics.

  The charge transport layer is preferably formed by dissolving the binder resin and the charge transport material to prepare a coating solution, applying the coating solution to a certain film thickness with a coating machine, and drying the coating film.

  Examples of the solvent for dissolving the binder resin and the charge transport material include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, and tetrahydrofuran. 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine, and the like, but are not limited thereto.

  The mixing ratio of the charge transport material to the binder resin is preferably 10 to 500 parts by mass, more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the binder resin.

  The thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 5 to 40 μm, and more preferably 10 to 30 μm.

  An antioxidant, an electronic conductive agent, a stabilizer and the like may be added to the charge transport layer. As the antioxidant, those described in JP-A No. 2000-305291 and as the electronic conductive agent are described in JP-A Nos. 50-137543 and 58-76483.

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

  FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

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

  The image forming unit 10Y that forms a yellow image includes a charging roller charging unit (charging step) 2Y arranged in contact with the periphery of a drum-shaped photoconductor 1Y as a first image carrier, and an exposure unit ( Exposure process) 3Y, developing means (developing process) 4Y, primary transfer roller 5Y as primary transfer means (primary transfer process), and cleaning means 6Y. The image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, 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 are charging means 2Y, 2M, 2C, and 2Bk of charging rollers that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk in contact with the photosensitive body. And image exposing means 3Y, 3M, 3C, 3Bk, rotating developing means 4Y, 4M, 4C, 4Bk, and cleaning means 6Y, 6M, 6C, 6Bk for cleaning the photosensitive drums 1Y, 1M, 1C, 1Bk. It is made up of.

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

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

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

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure unit 3Y, a unit composed of LEDs and light-emitting elements in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y, a laser optical system, or the like is used.

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

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

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

  On the other hand, the endless belt-shaped intermediate transfer body 70 obtained by transferring the color image to the image support P by the secondary transfer roller 5b as the secondary transfer means and then separating the curvature of the image support P has a residual toner by the cleaning means 6b. Removed.

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

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the image support P passes through the secondary transfer roller 5b and the secondary transfer is performed.

  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.

  FIG. 2 shows a configuration example of the charging roller used in the charging unit of FIG. As shown in FIG. 2, the charging roller 22R includes a cored bar 22a and a rubber layer such as chloroprene rubber, urethane rubber, silicone rubber or the like, which is a conductive elastic member provided on the outer periphery thereof, or a sponge layer 22b thereof. Is formed by providing a protective layer 22c made of a releasable fluorine-based resin or silicone resin layer having a thickness of 0.01 to 1 μm on the outermost layer.

  The charging roller is preferably brought into contact with the photoreceptors 1Y, 1M, 1C, and 1Bk with a pressure contact force of 10 to 100 g / cm. The rotation of the charging roller is preferably 1 to 8 times the peripheral speed of the photosensitive drum.

  In addition, as a contact charging type charging unit, a charging brush may be used instead of the charging roller.

  In the image forming apparatus of FIG. 1, a contact charging type color laser printer is shown, but it is of course applicable to a monochrome laser printer and a copy as well. The exposure light source may also be a light source other than a laser, such as an LED light source.

  Next, the present invention will be further described while showing actual configurations and effects. However, of course, the embodiments of the present invention are not limited to these. In the following text, “part” means “part by mass”.

(Preparation of photoreceptor 1)
Photoreceptor 1 was produced as follows.

  The surface of a cylindrical aluminum support having a diameter of 60 mm was cut to prepare a conductive support having a fine and rough surface.

<Intermediate layer>
A dispersion having the following composition was diluted twice with the same mixed solvent, and allowed to stand overnight, followed by filtration (filter; using a lime mesh 5 μm filter manufactured by Nihon Pall) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part Titanium oxide SMT500SAS (manufactured by Teika) 3 parts Methanol 10 parts Dispersion was carried out for 10 hours in a batch manner using a sand mill as a disperser.

  It apply | coated by the dip coating method so that it might become a dry film thickness of 2 micrometers on the said support body using the said coating liquid.

<Charge generation layer>
Charge generation material: titanyl phthalocyanine pigment (titanyl phthalocyanine pigment having a maximum diffraction peak at a position of at least 27.3 ° by Cu-Kα characteristic X-ray diffraction spectrum measurement) 20 parts polyvinyl butyral resin (# 6000-C: Electrochemical Industry) 10 parts) t-butyl acetate 700 parts 4-methoxy-4-methyl-2-pentanone 300 parts were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm.

<Charge transport layer>
Charge transport material (4,4′-dimethyl-4 ″-(β-phenylstyryl) triphenylamine) 225 parts Binder: Polycarbonate Z (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Antioxidant (Irganox 1010: BASF Japan) 6 parts THF (tetrahydrofuran) 1600 parts Toluene 400 parts Silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part was mixed and dissolved to prepare a charge transport layer coating solution.

  This coating solution was applied onto the charge generation layer using a circular slide hopper coating machine to form a charge transport layer having a dry film thickness of 20 μm.

<Protective layer>
Using tin oxide particles having a number average primary particle diameter of 30 nm as the metal oxide particles, using the exemplary compound (S-15) as the compound having a radical polymerizable functional group, and using the radical polymerizable functional group as shown below Preparation of the surface treatment with the compound having was carried out.

  First, a mixed solution of 100 parts of tin oxide particles having a number average primary particle diameter of 30 nm, 100 parts of the above exemplary compound (S-15), and 300 parts of a mixed solvent of toluene / isopropyl alcohol = 1/1 (mass ratio) is obtained. The mixture was placed in a sand mill together with the beads and stirred at about 40 ° C. at a rotation speed of 1500 rpm, and surface treatment with a compound having a radical polymerizable functional group of tin oxide particles was performed. Further, the above treatment mixture is taken out, put into a Henschel mixer, stirred for 15 minutes at a rotational speed of 1500 rpm, and then dried at 120 ° C. for 3 hours, whereby the surface treatment of the tin oxide particles with the compound having a radical polymerizable functional group is performed. When finished, surface-treated tin oxide particles 1 were obtained. The surface of the tin oxide particles was coated with the compound having a radical polymerizable functional group by the surface treatment with the compound having the radical polymerizable functional group.

  In this case, the surface treatment amount of the compound having a radical polymerizable functional group (the coating amount of the compound having a radical polymerizable functional group) is 100% by mass with respect to the tin oxide particles (that is, with respect to 100 parts by mass of the tin oxide particles). The surface treatment amount of the compound having a radical polymerizable functional group was 100 parts by mass).

  Subsequently, a protective layer was formed by the following method.

Tin oxide particles 1 having a surface-treated number average primary particle diameter of 30 nm (surface-treated with S-15) 100 parts Polymerizable compound (exemplary compound (Mc-1)) 100 parts Carbon nanotube A (average diameter: 2. 5 nm Length: 60 μm armchair type single-walled carbon nanotubes) 1 part Polymerization initiator (Exemplified Compound 1-6) 30 parts Chain transfer agent (2-mercaptobenzoxazole) 10 parts n-propyl alcohol 400 parts Mixing the above components The mixture was stirred and sufficiently dissolved and dispersed to prepare a surface layer coating solution. A surface layer was applied to the photoreceptor on which the coating solution had been prepared up to the charge transport layer using a circular slide hopper coater. After the coating, ultraviolet rays were irradiated for 1 minute using a metal halide lamp to obtain a protective layer having a dry film thickness of 3.0 μm.

(Preparation of photoconductors 2 to 16)
Photoconductors 2 to 16 were prepared in the same manner as in preparation of photoconductor 1, except that the surface-treated metal oxide particles, the polymerizable compound, the carbon nanotube, and the like of the protective layer were changed as shown in Table 1.

(Preparation of photoconductor 17)
Photoconductor 17 was prepared in the same manner as in the preparation of photoconductor 1, except that carbon nanotube A in the protective layer was omitted.

(Preparation of photoconductor 18)
In the production of the photoreceptor 1, the surface treatment agent for the metal oxide of the protective layer was the same except that the S-15 was changed to (3,3,3-trifluoropropyl) trimethoxysilane compound (hydrophobization treatment agent). Thus, a photoreceptor 18 was produced.

(Preparation of photoconductor 19)
Photosensitive member 19 was prepared in the same manner as in preparation of photosensitive member 1, except that a polycarbonate (polycarbonate Z (Z300)) was used instead of the polymerizable compound in the protective layer.

In Table 1,
The carbon nanotube A is an armchair type single-walled carbon nanotube carbon nanotube B having an average diameter of 2.5 nm and a length of 60 μm, and the zigzag single-walled carbon nanotube carbon nanotube C having an average diameter of 1.8 nm and a length of 30 μm is Average diameter: 2.1 nm Length: 20 μm Chiral type single-walled carbon nanotube Evaluation Basically, a bizhub PRO C6501 remodeling machine manufactured by Konica Minolta Business Technologies Co., Ltd. having a configuration of FIG. 1 (charger having a diameter of 15 mm shown in FIG. 2) Each photoreceptor was mounted on a charging roller and evaluated.

  In 23 ° C / 50% RH environment, endurance test was performed in which a character image with an image ratio of 6% was printed continuously on both sides of A4 paper and 300,000 sheets each in landscape feed. During or after the endurance test, the photoconductor Wear resistance, dash marks, residual potential and image memory were evaluated. The evaluation was performed according to the following indicators.

Evaluation of Abrasion Resistance Characteristics The film thickness of the protective layer before and after the durability test was measured, and the film thickness was calculated and evaluated.

  The thickness of the protective layer is measured at 10 points at random on the uniform film thickness portion (excluding the film thickness fluctuation portions at the front and rear ends of the coating), and the average value is measured for the protective layer film. Thickness. The film thickness measuring device is an eddy current method film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference in protective layer film thickness before and after the actual shooting test is defined as the film thickness depletion amount.

A: Film thickness reduction is less than 0.7 μm: (good)
○: 0.7 to 2.0 μm: (No problem in practical use)
×: larger than 2.0 μm: (practical problem)
Evaluation of dash mark After the endurance test, a halftone image was printed on A4 paper, and the occurrence of a dash mark (small comet-like streak image) whose periodicity coincides with the period of the photoconductor on the halftone image is shown below. Judged by criteria.

A: Frequency of dash marks of 0.4 mm or more: All printed images are 5 / A4 or less (good)
O: Frequency of dash marks of 0.4 mm or more: 1 or more of 6 / A4 or more and 10 / A4 or less (no problem in practical use)
X: Frequency of dash mark image defects of 0.4 mm or more: 11 or more A4 or more occurred (practical problem)
Evaluation of transfer dropout After the endurance test, the A4 paper is printed on both sides of an 8 mm grid chart with 200 mm, 500 μm, 1 mm, and 2 mm line widths for both vertical and horizontal lines. Ten places were observed visually and with a magnifying glass (× 30) and classified into the following evaluation ranks.

◎: No transfer omission (good)
○: Observation with a 30x magnifier reveals a lack of transfer in part of the field of view (no problem in practice)
×: Visually confirmed transfer missing (practical problem)
Evaluation of residual potential It evaluated by the magnitude | size of the electric potential fluctuation | variation of the exposure part potential in the said endurance test.

  Judgment criteria are as shown below.

  The initial charging potential was adjusted to 600 ± 50 V, and evaluation was performed based on the amount of change (ΔV) in the exposed portion potential after the initial and 50,000 sheets.

A: ΔV is less than 50V (good)
○: ΔV is 50 to 100 V (no problem in practical use)
×: ΔV is larger than 100V (practical problem)
Evaluation of image memory After the endurance test, ten solid black and solid white mixed images were printed in succession, followed by printing a uniform halftone image, and the solid black and solid white in the halftone image. Judgment was made based on whether or not the history of.

  Judgment criteria are as shown below.

  With respect to the image at the end of the durability test, the reflection density was measured using an SPI filter using a Macbeth reflection densitometer RD-918 (manufactured by Macbeth), and classified into the following evaluation ranks.

  ΔID is the difference between the density of the solid white history portion and the density of the solid black history portion.

A: ΔID is less than 0.05 (good)
○: ΔID is 0.05 to 0.10 (no problem in practical use)
×: ΔID is larger than 0.10 (practical problem)
The evaluation results are summarized in Table 2.

  From the results shown in Table 2, as a photoreceptor used in an image forming apparatus using a contact charging method, the protective layer contains a metal oxide, a polymerizable compound, and a carbon nanotube that are surface-treated with a compound having a radical polymerizable functional group. Using organic photoreceptors (photoreceptors Nos. 1 to 16) that are resin layers formed from the composition, the wear resistance is improved, and also in each evaluation of dash mark, transfer dropout, residual potential, and image memory. It has been evaluated as good or practically satisfactory.

  On the other hand, the photoreceptor No. of the comparative example. In No. 17 (without carbon nanotube), the increase in residual potential is large, and image memory is also generated. The photosensitive member No. In the 18 metal oxide surface treatment agent, since the metal oxide particles exist independently of the resin structure of the protective layer, the hardness of the protective layer is weaker than that of the photoreceptor in the present invention. The wear characteristics have deteriorated and image memory has also been generated. The photosensitive member No. In the photosensitive member using polycarbonate (polycarbonate Z (Z300)) instead of the 19 protective layer polymerizable compound, the wear resistance is further greatly deteriorated and an image memory is also generated.

1Y, 1M, 1C, 1Bk photoconductor 2Y, 2M, 2C, 2Bk charging unit 3Y, 3M, 3C, 3Bk exposure unit 4Y, 4M, 4C, 4Bk developing unit 10Y, 10M, 10C, 10Bk Image forming unit 7 Intermediate transfer member P Image support (also called transfer material, plain paper, etc.)

Claims (6)

  An organic photoreceptor having a photosensitive layer and a protective layer on a conductive support, wherein the protective layer is a composition containing a metal oxide, a polymerizable compound, and carbon nanotubes that are surface-treated with a compound having a radical polymerizable functional group. An organic photoreceptor, which is a formed resin layer.   The organophotoreceptor according to claim 1, wherein the carbon nanotube is an armchair single-walled carbon nanotube.   3. The organophotoreceptor according to claim 1, wherein the radical polymerizable functional group is an acryloyl group or a methacryloyl group.   The organophotoreceptor according to claim 1, wherein the polymerizable compound is an acrylic monomer or oligomer having an acryloyl group or a methacryloyl group.   5. An image forming apparatus having a charging means for charging by bringing a charging member into contact with the organic photosensitive member, wherein the organic photosensitive member is the organic photosensitive member according to claim 1.   An image forming method comprising forming an electrophotographic image using the image forming apparatus according to claim 5.

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