JP2012198278A - Organic photoreceptor, image forming device and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic photoreceptor, an image forming device and image forming method for solving the problems in a protection layer of an acrylic crosslinked cured resin, while preventing an increase in residual potential and occurrence of transfer memory to stably form an electrophotographic image of good quality for a long time.SOLUTION: In an organic photoreceptor, a protection layer contains at least a component to be obtained by curing a polymerizable compound, metal oxide particles having a volume resistivity (Ω cm) of 1×10to 1×10, and a non-reactive charge transport material. The ionization potential (Ip) of the non-reactive charge transport material contained in the protection layer and the ionization potential (Ip) of the charge transport material contained in a charge transport layer have a specific relation.

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.

  On the other hand, recent image forming methods have been digitized, and image forming methods using laser light as an exposure light source are 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 a contact member such as a cleaning 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, the improvement in the wear resistance of the organic photoreceptor using the binder is not sufficient. In particular, when an electron transporting compound is contained in the surface layer, the improvement effect is not significant.

  Next, in order to improve the wear resistance of the photoreceptor, the surface layer of the photoreceptor is treated with an acrylic polymerizable compound, a charge transporting compound having a polymerizable functional group, and a surface treatment agent having a polymerizable functional group. There has been proposed a photoreceptor provided with a protective layer of a cross-linked cured resin formed from the composition of the metal oxide particles formed (Patent Document 2).

  However, in the protective layer of the acrylic cross-linked cured resin described in Patent Document 2, since the charge transporting compound is incorporated as part of the resin structure, the effect of improving the charge transporting property of the protective layer is small. There is a problem that an increase in potential and image memory (especially, transfer memory due to reverse polarity charging during transfer) are likely to occur.

Japanese Patent Application Laid-Open No. 60-172044 JP 2010-169725 A

  An object of the present invention is to provide an organic photoreceptor, an image forming apparatus, and an image forming method capable of solving the problems of the protective layer of the acrylic cross-linked cured resin.

  Further, the object of the present invention is to improve the anti-wear property and to prevent the increase of the residual potential and the generation of the transfer memory, and to perform stable and long-term electrophotographic image formation. An organic photoreceptor, an image forming apparatus, and an image forming method are provided.

  In order to solve the above-mentioned problems, the present inventors have reduced the injection barrier of charge carriers from the charge transport layer into the protective layer of the acrylic cross-linked cured resin, and further moved the charge carriers in the protective layer itself. Based on the idea that it is necessary to include a substance to facilitate in the protective layer, each material in the protective layer of the acrylic cross-linked cured resin, as a result of detailed examination, as a result, The present invention has been achieved by finding conditions for reducing the injection barrier of charge carriers from the charge transport layer and conditions for substances that facilitate the movement of charge carriers in the protective layer itself.

  That is, the present invention is achieved by using an organic photoreceptor having the following configuration.

1. In an organic photoreceptor in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated on a conductive support, the protective layer includes at least a component obtained by curing a polymerizable compound and volume resistivity (Ω · cm). Contains 1 × 10 ³ to 1 × 10 ¹¹ metal oxide particles and a non-reactive charge transport material, and the ionization potential (Ip _{(C-OCL) of the} non-reactive charge transport material contained in the protective layer. ₎ ) And an ionization potential (Ip _(C-CTL) ) of a charge transport material contained in the charge transport layer can be represented by the following general formula (1).

General formula (1)
Ip _(C-OCL) ≤ Ip _(C-CTL)
2. 2. The organophotoreceptor according to 1 above, wherein the metal oxide particles are surface-treated with a surface treatment agent having a methacryloyl group or an acryloyl group.

  3. 3. The organophotoreceptor according to 1 or 2, wherein the metal oxide particles are any one or more selected from tin oxide, titanium oxide, and zinc oxide.

  4). In the image forming apparatus having a charging unit, an exposing unit, a developing unit, and a transfer unit around the organic photoconductor, the organic photoconductor is the organic photoconductor according to any one of the above 1-3. An image forming apparatus.

  5). 5. An image forming method, wherein an electrophotographic image is formed using the image forming apparatus described in 4 above.

  By using the organophotoreceptor of the present invention, it is possible to improve the anti-abrasion property, and further prevent an increase in residual potential and generation of a transfer memory, and stably form a good electrophotographic image in the long term. It is to provide an organic photoreceptor that can be performed.

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

  Hereinafter, the present invention will be described in detail.

The organic photoreceptor of the present invention is an organic photoreceptor in which a charge generation layer, a charge transport layer and a protective layer are sequentially laminated on a conductive support, wherein the protective layer comprises at least a component obtained by curing a polymerizable compound. Containing the metal oxide particles having a volume resistivity (Ω · cm) of 1 × 10 ³ to 1 × 10 ¹¹ and a non-reactive charge transport material, the non-reactive charge transport material included in the protective layer The ionization potential (Ip _(C-OCL) ) and the ionization potential (Ip _(C-CTL) ) of the charge transport material contained in the charge transport layer can be expressed by the following general formula (1).

General formula (1)
Ip _(C-OCL) ≤ Ip _(C-CTL)
The organophotoreceptor of the present invention has the above-described structure, and further improves the anti-abrasion property, and further prevents an increase in residual potential and the generation of a transfer memory. It is an object of the present invention to provide an organic photoreceptor that can perform image formation.

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

The protective layer according to the present invention contains metal oxide particles having a volume resistivity (Ω · cm) of 1 × 10 ³ to 1 × 10 ¹¹ .
[Metal oxide particles having a volume resistivity (Ω · cm) of 1 × 10 ³ to 1 × 10 ¹¹ ]
As the metal oxide particles having the above-mentioned volume resistivity characteristics, for example, any of the metal oxide particles including transition metals, for example, silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina ( Examples of the metal oxide particles include aluminum oxide), zirconium oxide, tin oxide, titania (titanium oxide), niobium oxide, molybdenum oxide, and vanadium oxide. Of these, tin oxide, titanium oxide, and zinc oxide are preferable.

  The volume resistivity (Ω · cm) of the metal oxide fine particles is obtained as follows.

  An electrical resistance is generally used as a measure of the conductivity of a substance. A value indicating this resistance per unit volume (1 cm × 1 cm × 1 cm) is a volume resistivity (unit Ω · cm).

  That is, it is obtained by passing a constant current I (A) through the cross-sectional area W × t and measuring the potential difference V (V) between the electrodes separated by the distance L.

Definition of volume resistivity (Ω · cm) Cross-sectional area = W x t
Resistance R = V / I
Volume resistivity VR (Ω · cm) = (W × t / L) × (V / I)
The volume resistivity (Ω · cm) of the metal oxide fine particles described in the present invention is such that a container having electrodes arranged in parallel at intervals of 2 mm is filled with metal oxide fine particles and the like, and the direct current resistance at a potential difference of 500 V between both electrodes. Was measured by Yokogawa Hewlett-Packard Co., Ltd. 4329A High Resistance Meter.

  Although the manufacturing method of the metal oxide particle of this invention does not have limitation in particular, For example, the indirect method (French method) described in JISK1410, the direct method (American method), or the plasma method etc. are mentioned.

  The number average primary particle size of the metal oxide particles of 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 particles surface-treated with a treatment agent having a radical polymerizable functional group)
The metal oxide particles according to the present invention are preferably surface-treated with a treatment agent having a radical polymerizable functional group, particularly a surface treatment agent having an acryloyl group or a methacryloyl group.

  Examples of the surface treatment agent having an acryloyl group or a methacryloyl group include the following compounds.

_{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

  The amount of the surface treatment agent to be treated with the metal oxide particles is preferably 0.1 to 200 parts by mass of the surface treatment agent with respect to 100 parts by mass of the metal oxide particles before the treatment.

[Production Method of Metal Oxide Particles Surface-treated with Treatment Agent Having Radical Polymerizable Functional Group]
Hereinafter, a method for producing metal oxide particles surface-treated with a treating agent 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 radically polymerizable treating agent according to the present invention are obtained by subjecting the titanium oxide particles to a surface treatment using a silane compound having the radical polymerizable functional group (the exemplified compound). , You can get. 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 dispersive devices are pulverized and dispersed by impact crushing, friction, cutting, shear stress, etc., using a grinding medium 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. In addition, these polymerizable compounds may use monomers, but may be used after oligomerization.

  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

  On the other hand, as the thermal polymerization initiator, ketone peroxide compounds, peroxyketal compounds, hydroperoxide compounds, dialkyl peroxide compounds, diacyl peroxide compounds, peroxydicarbonate compounds, peroxyester compounds Compounds and the like are used, and these thermal polymerization initiators are disclosed in company product catalogs.

  In the present invention, these thermal polymerization initiators are mixed with a composition containing treated metal oxide particles and, if necessary, a radical polymerizable compound in the same manner as the photopolymerization initiator, A surface layer coating solution is prepared, and the coating solution is coated on the photosensitive layer and then dried by heating to form the 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.

[Non-reactive charge transport material]
The protective layer according to the present invention also contains a non-reactive charge transport material.

  Here, the non-reactive charge transport material is not reactive with the above-described polymerizable compound, surface-treated metal oxide particles, etc., and does not change in the protective layer, and the protective layer resin. Means a charge transporting compound which can exist independently without bonding.

  In addition, the non-reactive charge transport material is in the relationship of the general formula (1) with the charge transport material in the charge transport layer stacked under the protective layer and the ionization potential (Ip). is required.

  By having such a relationship of the general formula (1), the movement of charge carriers from the charge transport layer to the protective layer becomes smooth, and an increase in residual potential and generation of transfer memory can be prevented.

  Examples of combinations of charge transport materials having the relationship of the general formula (1) and excellent in sensitivity and potential stability are shown below.

  Although it is necessary to determine the charge transport material of the protective layer and the charge transport layer after satisfying the relational expression of the general formula (1), the charge transport material used for the protective layer of the present invention is exemplified below. It is preferable to use a charge transport material. The ionization potential (Ip) is described together with the structural formula of the charge transport material below.

  The charge generation material can be synthesized by a known synthesis method, for example, a synthesis method described in JP 2010-26428 A, JP 2010-91707 A, or the like.

  The ionization potential (Ip) of the charge transport material according to the present invention was a value measured by photoelectron spectroscopy, specifically, a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd.

  The protective layer according to the present invention is prepared by preparing a composition in which the above-described metal oxide particles, a polymerizable compound, a non-reactive charge transport material, a polymerization initiator, and the like are mixed in a solvent, and the charge is described later. After coating on the transport layer, it can be dried and cured to form a resin layer as a protective layer. The resin layer of the protective layer proceeds by mixing the reaction between the radical polymerizable functional groups of the metal oxide particles, the reaction between the radical polymerizable functional group and the polymerizable compound, the reaction between the polymerizable compounds, etc. A resin layer is formed.

  The ratio of the metal oxide particles in the protective layer is preferably 20 to 50% by mass of the metal oxide particles when the resin layer of the protective layer is 100% by mass as a whole.

  The proportion of the non-reactive charge transport material in the protective layer is preferably 3 to 15% by mass of the non-reactive charge transport material when the resin layer of the protective layer is 100% by mass as a whole.

  Each mass% above is verified from the mass of the protective layer, the mass detected by decomposing the resin layer component of the protective layer, taking out the metal oxide particles, and the mass detected by taking out the non-reactive charge transport material, etc. can do.

  In this way, by incorporating the charge transport material satisfying the general formula (1) into the curable protective layer according to the present invention, trapping of charge carriers in the protective layer is prevented, and the increase in residual potential and image memory are achieved. Generation of (transfer memory) and the like can be prevented.

  The protective layer of the present invention can further contain various 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 has a layer structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated as a photosensitive layer on a conductive support. In addition, an intermediate layer is preferably provided between the conductive support and the charge generation layer.

  The layer structure of the organophotoreceptor of the present invention will be described focusing on the above.

(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.

  Charge generation materials 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 polycyclic quinone pigments such as pyranthrone and diphthaloylpyrene And phthalocyanine pigments, but are not limited thereto. 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.

  The charge transport material needs to satisfy the general formula (1), and various known charge transport materials can be used. For example, carbazole derivative, oxazole derivative, oxadiazole derivative, thiazole derivative, thiadiazole derivative, triazole derivative, imidazole derivative, imidazolone derivative, imidazolidine derivative, bisimidazolidine derivative, styryl compound, hydrazone compound, pyrazoline compound, oxazolone derivative, benz Imidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene and poly-9 -Two or more kinds of vinyl anthracene, triphenylamine derivatives, etc. 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.

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

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

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

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

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

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure 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-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. 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 subjected to fixing processing by the fixing means 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper 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 is subjected to 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.

  Although the color laser printer is shown in the image forming apparatus of FIG. 1, it is of course applicable to a monochrome laser printer and copying 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: Pigment (CG-1) below: Mixed crystal of 1: 1 adduct of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol and non-adduct titanyl phthalocyanine 20 parts Polyvinyl butyral resin (# 6000) -C: manufactured by Denki Kagaku Kogyo Co., Ltd.) 10 parts t-butyl acetate 700 parts 4-methoxy-4-methyl-2-pentanone 300 parts are mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. did. 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.

(Synthesis of Pigment (CG-1))
(1) Synthesis of amorphous titanyl phthalocyanine 1,3-diiminoisoindoline; 29.2 parts by mass are dispersed in 200 parts by mass of o-dichlorobenzene, and titanium tetra-n-butoxide; 20.4 parts by mass are added. It heated at 150-160 degreeC for 5 hours under nitrogen atmosphere. After allowing to cool, the precipitated crystals were filtered, washed with chloroform, washed with 2% aqueous hydrochloric acid, washed with water, washed with methanol, and dried to obtain 26.2 parts by mass (yield 91%) of crude titanyl phthalocyanine.

  Subsequently, the crude titanyl phthalocyanine was dissolved by stirring for 1 hour in 250 parts by mass of concentrated sulfuric acid at 5 ° C. or less, and this was poured into 5000 parts by mass of water at 20 ° C. The precipitated crystals were filtered and sufficiently washed with water to obtain 225 parts by mass of a wet paste product.

  Subsequently, the wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain 24.8 parts by mass of amorphous titanyl phthalocyanine (yield 86%).

(2) Synthesis of (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine (CG-1) 10.0 parts by mass of the above-mentioned amorphous titanyl phthalocyanine and (2R, 3R) -2,3-butanediol 0.94 parts by mass (0.6 equivalent ratio) (equivalent ratio is equivalent ratio to titanyl phthalocyanine, hereinafter the same) was mixed in 200 parts by mass of orthochlorobenzene (ODB), and heated and stirred at 60 to 70 ° C. for 6.0 hours. . After standing overnight, methanol was added to the reaction solution, and the resulting crystals were filtered. The crystals after filtration were washed with methanol (a pigment containing (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine). CG-1: 10.3 mass parts was obtained. In the X-ray diffraction spectrum of CG-1, there are clear peaks at 8.3 °, 24.7 °, 25.1 °, and 26.5 °. There is a peak in the 576 and 648 in the mass spectra, O-Ti-O both absorption appears Ti = O near 970 cm ^-1, around 630 cm ^-1 in the IR spectrum. In addition, since thermal analysis (TG) has a mass loss of about 7% at 390 to 410 ° C., a 1: 1 adduct and a non-adduct (addition) of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol It is presumed to be a mixed crystal of titanyl phthalocyanine.

It was 31.2 m < ² > / g when the BET specific surface area of the obtained CG-1 was measured with the flow type specific surface area automatic measuring device (Micrometrics flow soap type: Shimadzu Corporation).

<Charge transport layer>
Charge transport material (Exemplary CTM-10: Ip (5.39 eV) 225 parts Binder: Polycarbonate Z (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Antioxidant (Irganox 1010: manufactured by Ciba-Geigy Corporation of Japan) 6 parts THF (tetrahydrofuran) 1600 Part 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 A having the following characteristics as the metal oxide particles, using the exemplary compound (S-15) as the compound having a radical polymerizable functional group, and the surface of the compound having a radical polymerizable functional group as shown below Treatment preparations were made.

  First, a mixed solution of 100 parts of tin oxide A, 30 parts of the above exemplary compound (S-15) and 300 parts of a mixed solvent of toluene / isopropyl alcohol = 1/1 (mass ratio) is put in a sand mill together with zirconia beads at about 40 ° C. The mixture was stirred at a rotational speed of 1500 rpm and subjected to surface treatment with a compound having a radical polymerizable functional group of titanium oxide particles. Further, the above treatment mixture is taken out, put into a Henschel mixer, stirred at a rotational speed of 1500 rpm for 15 minutes, and then dried at 120 ° C. for 3 hours to complete the surface treatment of tin oxide with the compound having a radical polymerizable functional group. As a result, surface-treated tin oxide A was obtained. The surface of the tin oxide A particles was coated with the compound of S-15 by the surface treatment with the compound having the radical polymerizable functional group.

  In addition, the tin oxide A is a tin oxide having the following characteristics manufactured by CIK Nanotech.

Number average primary particle size: 20 nm, volume resistivity: 1.05 × 10 ⁴ (Ω · cm)
Subsequently, a protective layer was formed by the following method.

Surface-treated tin oxide A (surface-treated with S-15) 50 parts Polymerizable compound (exemplary compound (Mc-1)) 100 parts Charge transport material (exemplary CTM-10: Ip (5.39 eV) 15 parts Polymerization Initiator (Exemplary Compound 1-6) 30 parts Chain transfer agent (2-mercaptobenzoxazole) 10 parts n-propyl alcohol 400 parts The above components were mixed and stirred, and sufficiently dissolved and dispersed to prepare a surface layer coating solution. The surface layer was applied onto the photoconductor having the coating solution prepared up to the charge transport layer by using a circular slide hopper coater, and after application, the coating was irradiated with ultraviolet rays for 1 minute using a metal halide lamp to form a dry film. A photosensitive layer 1 was prepared by forming a protective layer having a thickness of 3.0 μm.

(Production of photoconductors 2 to 20)
In the production of the photoreceptor 1, the same procedure was performed except that the metal oxide particles in the protective layer, the surface treatment agent, the polymerizable compound, the charge transport material in the charge transport layer, and the like were changed as shown in Table 1. 20 was produced.

(Preparation of photoconductor 21)
Photoreceptor 1 was prepared in the same manner except that the metal oxide particles of the protective layer were changed to titanium oxide (number average primary particle size: 30 nm, volume resistivity: 1.5 × 10 ¹³ Ω · cm). A body 21 was produced.

(Preparation of photoconductor 22)
Photosensitive body 1 was prepared in the same manner except that the metal oxide particles of the protective layer were changed to tin oxide (number average primary particle diameter: 6 nm, volume resistivity: 5.0 × 10 ² Ω · cm). A body 22 was produced.

(Preparation of photoconductor 23)
In the production of the photoconductor 1, the photoconductor 23 was prepared in the same manner except that CTM-9 was changed to 300 parts by mass as the charge transport material of the charge transport layer and CTM-1 was changed to 15 parts by mass as the charge transport material of the protective layer. Produced.

(Preparation of photoconductor 24)
In the production of the photoreceptor 1, a photoreceptor 24 was produced in the same manner except that a polycarbonate (polycarbonate Z (Z-300)) was used instead of the polymerizable compound in the protective layer.

(Preparation of photoconductor 25)
In the production of the photoreceptor 1, instead of the charge transport material CTM-10 (non-reactive charge generation material) of the protective layer, 20 parts by mass of the following reactive charge transport material RCTM-5 described in JP 2010-169725 A A photoconductor 25 was produced in the same manner as described above. A charge transporting group is incorporated in the resin structure of the protective layer of the photoreceptor 15.

In Table 1,
Tin oxide A: Number average primary particle size: 20 nm, volume resistivity: 1.05 × 10 ⁴ (Ω · cm), manufactured by CIK Nanotech Co., Ltd. Tin oxide B: Number average primary particle size: 6 nm, volume resistivity: 5. 36 × 10 ³ (Ω · cm), manufactured by Teika Co., Ltd. Tin oxide C: number average primary particle size: 30 nm, volume resistivity: 2.1 × 10 ⁵ (Ω · cm), manufactured by Mitsubishi Materials Corporation Titanium oxide A: Number Average primary particle size: 20 nm, volume resistivity: 3.01 × 10 ⁹ (Ω · cm), manufactured by CIK Nanotech, Inc. Titanium oxide B: Number average primary particle size: 6 nm, volume resistivity: 2.2 × 10 ⁸ ( (Ω · cm), manufactured by Teika, Inc., titanium oxide C: number average primary particle size: 30 nm, volume resistivity: 7.3 × 10 ⁶ (Ω · cm), manufactured by Titanium Industry Co., Ltd., zinc oxide A: number average primary particle size: 10 nm, volume ^{resistivity: 2.2 × 10 7 (Ω ·} cm), CIK Na Tech Co., Ltd. Zinc oxide B: number average primary particle diameter: 30 nm, volume ^{resistivity: 3.6 × 10 10 (Ω ·} cm), manufactured by Sakai Chemical Industry Co., Ltd. Zinc oxide C: number average primary particle diameter: 15 nm, volume resistivity : 1.1 × 10 ⁹ (Ω · cm), evaluation by Teica Co., Ltd. Bizhub PRO C6501 manufactured by Konica Minolta Business Technologies Co., Ltd. (color compound machine, exposure light is 780 nm semiconductor laser) having the configuration of FIG. Each photoconductor was mounted and evaluated.

  In a 23 ° C./50% RH environment, a durability test is performed in which a character image with an image ratio of 6% is printed on both sides of 300,000 sheets continuously with A4 horizontal feed. Wear characteristics, 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 photosensitive layer before and after the durability test was measured, and the amount of film thickness loss was calculated and evaluated.

  The film thickness of the photosensitive layer is measured randomly at 10 locations where the film thickness is uniform (excluding the film thickness fluctuation portion at the leading and trailing edges of the coating), and the average value is measured for the film of the photosensitive layer. Thickness. The film thickness measuring device is an eddy current film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference in the photosensitive layer thickness before and after the actual shooting test is defined as the film thickness depletion amount. The amount of wear per 100 krot (100,000 revolutions) is shown in Table 2 as an α value.

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 is made based on whether or not a history of memory appears (memory is generated) or not (memory is not generated).

○: No memory generated ×: Memory generated Evaluation results are summarized in Table 2.

  From the results of Table 2, the photoconductors (photoconductors Nos. 1 to 20) having the configuration of the present invention in which the ionization potential of the charge transport material of the protective layer and the charge transport layer has the relationship of the general formula (1) are as follows: Good evaluations have been obtained for each evaluation item.

  On the other hand, the volume resistivity of the metal oxide particles is the photoconductors 21 and 22 outside the present invention, the relationship between the ionization potential is the photoconductor 23 outside the present invention, the photoconductor 24 of the protective layer is polycarbonate, and the charge transport of the protective layer. In the photosensitive member 25 or the like, in which the substance is a reactive charge transport substance, the evaluation characteristics are greatly deteriorated in one or more of these evaluation items of wear resistance, residual potential, and image memory.

(Preparation of photoconductor 26)
In the production of the photoreceptor 1, the charge generation material of the charge generation layer is changed from the pigment (CG-1) to the following pigment (CG-2), and the charge transport materials of the charge transport layer and the protection layer are changed from CTM-10 to CTM-16. : Photoreceptor 26 was produced in the same manner except that Ip (5.55 eV) was used.

(Synthesis of Pigment (CG-2))
8,16-pyransrangeon 5.0 parts by mass and iodine 0.25 parts by mass were dissolved in 50 parts by mass of chlorosulfuric acid, and 5.9 parts by mass of bromine was added dropwise. The mixture was heated and stirred at 70 ° C. for 5 hours, cooled to room temperature, and then poured into 500 parts by mass of ice. Filtration, washing with water and drying were performed to obtain 8.5 parts by mass of a crude pigment product. Put 5.0 parts by weight of the crude pigment into a Pyrex glass tube, and place the tube in a temperature gradient of about 460 ° C. to about 20 ° C. along the length of the tube (1 m long, about 460 ° C. (With a temperature gradient of about 20 ° C.) was placed inside the furnace. The inside of the glass tube was depressurized to about 1 × 10 ⁻² Pa, and the position where the crude pigment to be purified was placed was heated to about 460 ° C. The generated vapor was moved and condensed on the low temperature side of the tube to obtain 3.3 parts by mass of sublimate condensed in a region between about 300 to 400 ° C.

  As a result of mass spectrum measurement, the number of Br was a mixture of n = 3 to 5, and the peak intensity ratio of n = 3 / n = 4 / n = 5 was 16/67/17.

(Production of photoconductors 27 and 28)
Photoconductors 27 and 28 were produced in the same manner except that the combination of the charge transport material of the photoconductor 26 and the charge transport material of the protective layer was changed as shown in Table 3 below.

Evaluation Each of the photoconductors 26 to 28 is mounted on an improved machine of bizhub PRO C6501 manufactured by Konica Minolta Business Technologies, Inc. (exposure light is changed to a 405 nm semiconductor laser) in the same manner as the photoconductor 1. The same evaluation was performed.

  The evaluation results are summarized in Table 4.

  The photoconductors 26 to 28 for the short-wave laser having the configuration of the present invention have obtained good results in each evaluation of wear resistance, residual potential, and image memory.

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 (5)

In an organic photoreceptor in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated on a conductive support, the protective layer includes at least a component obtained by curing a polymerizable compound and volume resistivity (Ω · cm). Contains 1 × 10 ³ to 1 × 10 ¹¹ metal oxide particles and a non-reactive charge transport material, and the ionization potential (Ip _{(C-OCL) of the} non-reactive charge transport material contained in the protective layer. ₎ ) And an ionization potential (Ip _(C-CTL) ) of a charge transport material contained in the charge transport layer can be represented by the following general formula (1).
General formula (1)
Ip _(C-OCL) ≤ Ip _(C-CTL)   The organophotoreceptor according to claim 1, wherein the metal oxide particles are surface-treated with a surface treatment agent having a methacryloyl group or an acryloyl group.   The organophotoreceptor according to claim 1, wherein the metal oxide particles are any one or more selected from tin oxide, titanium oxide, and zinc oxide.   The image forming apparatus having a charging unit, an exposing unit, a developing unit, and a transfer unit around the organic photoconductor, wherein the organic photoconductor is the organic photoconductor according to any one of claims 1 to 3. An image forming apparatus.   An image forming method comprising: forming an electrophotographic image using the image forming apparatus according to claim 4.

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