JP2021067915A - Electro-photographic photoreceptor, process cartridge, and electro-photographic apparatus - Google Patents

Abstract

To provide a single-layered electro-photographic photoreceptor having an undercoat layer between the photosensitive layer and a support and contains a charge generating substance, charge transporter and silica particles in the photosensitive layer, which is capable of improving charging performance.SOLUTION: An electro-photographic photoreceptor has a support body, an undercoat layer, and a photosensitive layer in this order. The photosensitive layer is a single-layered photosensitive layer that contains a charge-generating substance, a hole-transporting substance, an electron-transporting substance, silica particles, and a binding resin. In the electro-photographic photoreceptor, the undercoat layer contains titanium oxide particles with a specific surface area of 200 m2/g or more and less than 400 m2/g, an electron-accepting substance, and a binder resin.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrophotographic photosensitive member, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

Organic photoconductors are often used as electrophotographic photosensitive members used in electrophotographic apparatus.

The organic photoconductor includes a laminated photoconductor in which a charge generating layer made of a charge generating substance and a resin and a functional layer such as a charge transporting substance made of a binding resin are laminated, and a charge generating substance and a charge transporting substance. Single-layer photoconductors having the same layer are known.

The single-layer photoconductor has a smaller number of layers than the laminated photoconductor, and has a cost advantage because the production line can be simplified. From the viewpoint of cost reduction, a single-layer type photosensitive layer may be provided on the support, but due to charge injection from the support to the photosensitive layer, the charging ability is lowered, the image contrast is lowered, or the reverse development method is used. In that case, it may cause black spots or fog on a white background. Therefore, a method of providing an undercoat layer between the support and the photosensitive layer is used.

Patent Document 1 explains that it is preferable that the intermediate layer (for example, the undercoat layer formed on the substrate) contains the resin and the inorganic particles. Examples of inorganic particles include metal oxides (eg, titanium oxide, alumina, zirconium oxide, tin oxide, or zinc oxide). Then, a technique for improving the wear resistance of a single-layer electrophotographic photosensitive member by containing silica particles in the photosensitive layer is described.

Patent Document 2 discloses a single-layer photoconductor having an undercoat layer containing metal oxide particles such as antimony oxide, indium oxide, tin oxide, titanium oxide, and zinc oxide between the photosensitive layer and the substrate. There is.

Japanese Unexamined Patent Publication No. 2015-169801 JP 2015-172643

The present inventors have a single-layer electrophotographic photosensitive member having an undercoat layer between the photosensitive layer and the support and containing a charge generating substance, a charge transporting substance and silica particles in the photosensitive layer, due to poor charging. I noticed that image defects such as black spots and streaks in halftone images are likely to occur.

Therefore, an object of the present invention is to provide an electrophotographic photosensitive member having excellent durability and less likely to generate black spots and streaks in a halftone image, an electrophotographic apparatus having the electrophotographic photosensitive member, and a process cartridge.

Therefore, the present invention
It has a support, an undercoat layer, and a photosensitive layer in this order.
The photosensitive layer is an electrophotographic photosensitive member which is a single-layer photosensitive layer containing a charge generating substance, a hole transporting substance, an electron transporting substance, silica particles, and a binder resin.
Provided is an electrophotographic photosensitive member characterized in that the undercoat layer contains titanium oxide particles having a specific surface area of 200 m ² / g or more and ^{less than 400 m 2} / g, an electron accepting substance, and a binder resin. ..

According to the present invention, it is possible to provide an electrophotographic photosensitive member which is an electrophotographic photosensitive member having excellent durability and less likely to generate black spots or streaks in a halftone image, and an electrophotographic apparatus and a process cartridge having the same.

The schematic diagram which shows the electrophotographic apparatus which has the process cartridge provided with the electrophotographic photosensitive member.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

In the present invention, the photosensitive layer is a so-called single-layer electrophotographic photosensitive member, the undercoat layer contains silica particles, and the photosensitive layer contains titanium oxide particles, and the specific surface area of the titanium oxide particles is 200 m ² / g. It is a high numerical range of more than 400 m ^{2 / g.}

This will be described in detail below.

In a single-layer electrophotographic photosensitive member having an undercoat layer between the photosensitive layer and the support and containing a charge generating substance, a charge transporting substance, and silica particles in the photosensitive layer, the present inventors have a charge potential. I noticed that it tends to be non-uniform in the plane of the electrophotographic photosensitive member.

In an electrophotographic apparatus in which the charging time is shortened for the purpose of increasing the speed, charging non-uniformity is likely to occur and may appear as fine black spots in an image. Further, in the case of the method of charging the charging member in contact with the electrophotographic apparatus by applying only a direct current, abnormal discharge may occur due to the non-uniformity of charging, and fine streaks may occur in the halftone image.

An electrophotographic photosensitive member having an undercoat layer containing metal oxide particles between the photosensitive layer and the support was examined. As a result, titanium oxide having a large specific surface area was used as the metal oxide, and electrons were received in the undercoat layer. It has been found that the charge uniformity is improved by containing the sex compound.

The present inventors consider the reason why the charge uniformity is improved by the above configuration as follows.

The non-uniformity of charge is the microscopic in-plane potential unevenness of the photosensitive layer, and it is considered that the potential unevenness is caused by the charge trap at the interface between the photosensitive layer and the undercoat layer.

By including titanium oxide having a large specific surface area in the undercoat layer, charge transfer increases at the interface between the undercoat layer and the photosensitive layer, and charge trap sites are reduced. Furthermore, it is speculated that the inclusion of the electron-accepting compound smoothed the charge transfer between the undercoat layer and the photosensitive layer, and suppressed the non-uniformity of the charge.

[Electrophotophotoreceptor]
The electrophotographic photosensitive member of the present invention has a support, an undercoat layer, and a photosensitive layer in this order.

Specifically, the electrophotographic photosensitive member has an undercoat layer on the support and a photosensitive layer on the undercoat layer.

The surface of the photoconductor is the surface of the photosensitive layer. The electrophotographic photosensitive member of the present invention may further have a surface layer covering the photosensitive layer. In that case, the surface of the electrophotographic photosensitive member is the surface of the surface layer.

Examples of the method for producing the electrophotographic photosensitive member of the present invention include a method in which a coating liquid for each layer described later is prepared, applied in the order of desired layers, and dried. At this time, examples of the coating liquid coating method include immersion coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Among these, dip coating is preferable from the viewpoint of efficiency and productivity.

Hereinafter, each layer will be described.

<Underlay layer>
In the present invention, an undercoat layer is provided on the support. By providing the undercoat layer, the adhesive function between the layers is enhanced, and the charge injection blocking function can be imparted.

The undercoat layer preferably contains a resin. Further, an undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.

Resins used for the undercoat layer include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, and polypropylene. Examples thereof include oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin.

The undercoat layer further contains titanium oxide particles and an electron accepting substance in order to improve the charge uniformity of the surface of the electrophotographic photosensitive member.

The specific surface area of the titanium oxide particles, in order to improve the charge uniformity, 200 meters ² / g or more and less than 400m ² / g. The specific surface area is a value measured by the BET flow method (one-point method), and can be measured by a BET specific surface area measuring device (for example, Macsorb HM model 1210 manufactured by Mountech Co., Ltd.).

As the titanium oxide particles, crystalline particles having an anatas type, rutile type, and brookite type are preferable, and anatas type titanium oxide is particularly preferable, because the electric charge remaining in the photosensitive layer flows to the support.

The average primary particle size of the titanium oxide particles is preferably 5 nm or more and 9 nm or less in order to keep the specific surface area in the above range.

Further, the titanium oxide particles are preferably surface-treated in order to stabilize the electrical characteristics even if the environment in which the particles are arranged changes and to obtain high dispersibility in the undercoat layer. ..

Examples of the surface treatment agent include an organosilicon compound, a titanate-based coupling agent, a surfactant and the like, and an organosilicon compound is particularly preferable.

Preferable examples of the organosilicon compound are a trimetoxylene compound and a triethoxysilane compound having an alkyl group, a vinyl group, an amino group, a fluorine group and the like. Further, silicone oils such as silazane compounds, dimethyl silicone oil and methyl hydrogen polysiloxane are preferable.

Further, the surface of the titanium oxide particles may be treated with inorganic silica, inorganic alumina or the like.

Examples of the surface treatment method for the titanium oxide particles include a dry method and a wet method.

Examples of the method of performing the surface treatment by the dry method include a method of directly mixing and pulverizing the titanium oxide particles with the treatment agent while stirring with a mill or the like. Further, as a method of performing surface treatment by a wet method, there is a method of dispersing titanium oxide particles in a solvent, adding a surface treatment agent solution to further disperse the particles, and then removing the solvent, heat treatment and pulverization treatment. Be done. In the surface treatment step, the specific surface area of the titanium oxide particles can be set to 200 m ² / g or more ^{and less than 400 m 2} / g.

The amount of the surface treatment agent added is preferably 1% by mass or more and 30% by mass or less with respect to the titanium oxide particles. If it is less than 1% by mass, it is difficult to obtain dispersibility in the undercoat layer, and if it exceeds 30% by mass, the residual potential tends to increase.

The content of the titanium oxide particles is more preferably 60% by mass or more and less than 80% by mass with respect to the total mass of the undercoat layer. If it is less than 60% by mass, it may not be possible to improve the charge uniformity, and if it is 80% by mass or more, the charge injection from the support may be excessive and black spots may be generated on the image.

In addition, the undercoat layer contains an electron-accepting substance. Examples of the electron-accepting substance include a quinone compound, an anthraquinone compound, a benzophenone compound, a phthalocyanine compound, a fullerene compound, and a benzoxanthene compound. Of these, quinone compounds and anthraquinone compounds are preferable in order to improve charge uniformity.

The content of the electron-accepting compound is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.1% by mass or more and 10% by mass or less with respect to the titanium oxide particles.

The undercoat layer may further contain an additive such as resin particles for adjusting the surface roughness of the undercoat layer.

Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. Further, a leveling agent such as silicone oil may be added.

The average film thickness of the undercoat layer is preferably 0.1 μm or more and 50 μm or less, more preferably 0.2 μm or more and 40 μm or less, and particularly preferably 0.3 μm or more and 30 μm or less.

The undercoat layer can be formed by preparing a coating liquid for an undercoat layer containing each of the above-mentioned materials and solvents, forming this coating film, and drying and / or curing. Examples of the solvent used for the coating liquid include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like.

<Support>
In the present invention, the electrophotographic photosensitive member has a support. In the present invention, the support is preferably a conductive support having conductivity. Further, examples of the shape of the support include a cylindrical shape, a belt shape, a sheet shape, and the like. Above all, a cylindrical support is preferable. Further, the surface of the support may be subjected to an electrochemical treatment such as anodizing, a blasting treatment, a cutting treatment or the like.

As the material of the support, metal, resin, glass and the like are preferable.

Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Above all, it is preferable that the support is made of aluminum using aluminum.

Further, the resin or glass may be imparted with conductivity by a treatment such as mixing or coating a conductive material.

<Photosensitive layer>
The photosensitive layer of the electrophotographic photosensitive member has a photosensitive layer containing both a charge generating substance, a charge transporting substance, a resin, and inorganic particles.

Examples of the charge generating substance include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, phthalocyanine pigments and the like. Among these, a phthalocyanine pigment having high sensitivity in the near-infrared wavelength region of laser exposure used in an electrophotographic apparatus is preferable. Among these, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, hydroxygallium phthalocyanine pigments, and metal-free phthalocyanine pigments are particularly preferable.

The content of the charge generating substance is preferably 0.1% by mass or more and 50% by mass or less, and more preferably 0.5% by mass or more and 30% by mass or less with respect to the resin contained in the photosensitive layer.

Charge-transporting substances include hole-transporting substances that transport positive charges and electron-transporting substances that transport negative charges. In a single-layer photoconductor, both hole-transporting substances and electron-transporting substances are included. It is preferable to have.

Examples of the hole transporting substance include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Can be mentioned. Among these, triarylamine compounds and benzidine compounds are preferable.

The content of the hole transporting substance in the photosensitive layer is preferably 20% by mass or more and 150% by mass or less, and more preferably 50% by mass or more and 120% by mass or less with respect to the resin.

Examples of the electron transporting substance include a quinone compound and a cyclopentadienylidene compound. A suitable example is shown below. In the present invention, electron transport substances represented by the following formulas (1) to (5) are preferable.

Preferable examples of the quinone compound include a compound having a paraquinoid structure or an orthoquinoid structure. It may have a structure in which aromatic rings are condensed, or it may have a structure in which quinoid structures are connected to each other. Specifically, compounds represented by any of the following formulas (1) to (3) are preferable.

In the formula (1), R1 to R8 independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

In formula (2), R11 and R12 each independently represent a hydrogen atom, an alkoxy group, a phenyl group, a hydroxy group, or a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms.

In formula (3), R32 to R39 each independently represent a hydrogen atom, a halogen atom, a nitro group, or a substituted or unsubstituted alkyl group or aryl group. The alkyl group has 1 to 8 carbon atoms.

The aryl group may have an alkyl group, a halogen atom, a hydroxy group, a carboxy group, a nitro group or a cyano group. X21 and X22 independently represent a carbon atom or a nitrogen atom, respectively. When X21 is a nitrogen atom, R36 does not exist, and when X22 is a nitrogen atom, R35 does not exist.

R41 to R48 in the formula (4) independently represent a hydrogen atom, a halogen atom, an alkyl group, a hydroxy group, or a carboxy group. The alkyl group has 1 to 8 carbon atoms.

X31 and X32 independently represent a carbon atom or a nitrogen atom, respectively. When X31 is a nitrogen atom, R47 does not exist, and when X32 is a nitrogen atom, R43 does not exist.

Preferable examples of the cyclopentadienylidene compound include a compound having a cyclopentadienylidene structure. It may have a structure in which aromatic rings are condensed. Specifically, the compound represented by the following formula (5) is preferable.

In formula (5), R22 represents an oxygen atom, a dicyanomethylene group, or a phenylimino group. The phenylimino group may have an alkyl group. The alkyl group has 1 to 8 carbon atoms.

R23 to R30 independently represent a hydrogen atom, an alkoxycarbonyl group, or a nitro group. X11 and X12 independently represent a carbon atom or a nitrogen atom, respectively. If X11 is a nitrogen atom, R27 does not exist, and if X12 is a nitrogen atom, R26 does not exist.

The content of the electron transporting substance in the photosensitive layer is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 30% by mass or less with respect to the resin.

Examples of the resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin and the like. Among these, polycarbonate resin and polyester resin are preferable. As the polyester resin, a polyarylate resin is particularly preferable.

The photosensitive layer may have only the silica particles described above, but may also have other inorganic particles.

Examples of other inorganic particles include alumina particles, titanium oxide particles, tin oxide particles, zinc oxide particles, zirconium oxide particles, barium sulfate particles, calcium oxide particles, calcium carbonate particles, magnesium oxide particles and the like.

It is preferable that the silica particles are surface-treated in order to suppress deterioration of electrical characteristics even when the environment in which the photoconductor is present becomes highly humid.

Examples of the surface treatment agent include an organosilicon compound, a titanate-based coupling agent, a surfactant and the like, and an organosilicon compound is particularly preferable. Preferable examples of the organosilicon compound are a trimetoxylene compound and a triethoxysilane compound having an alkyl group, a vinyl group, an amino group, a fluorine group and the like. Further, silicone oils such as silazane compounds, dimethyl silicone oil and methyl hydrogen polysiloxane are preferable.

The average particle size of the silica particles is preferably 7 nm or more and 150 nm or less, and more preferably 20 nm or more and 100 nm or less.

The content of the silica particles is preferably 0.5% by mass or more and 15% by mass or less with respect to the resin in the photosensitive layer.

Further, the photosensitive layer may contain additives such as an antioxidant, an ultraviolet absorber, a plasticizer, a leveling agent, a slipperiness imparting agent, and an abrasion resistance improving agent. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, and polyethylene resin particles.

The average film thickness of the photosensitive layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

The photosensitive layer can be formed by preparing a coating liquid for a photosensitive layer containing each of the above-mentioned materials and a solvent, forming this coating film, and drying the coating film. Examples of the solvent used for the coating liquid include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents or aromatic hydrocarbon-based solvents are preferable.

[Process cartridge, electrophotographic equipment]
The process cartridge of the present invention integrally supports the electrophotographic photosensitive member described above and at least one means selected from the group consisting of charging means, developing means, transfer means and cleaning means, and is an electrophotographic apparatus. The feature is that it can be attached to and detached from the main body.

Further, the electrophotographic apparatus of the present invention is characterized by having the electrophotographic photosensitive member, charging means, exposure means, developing means and transfer means described above.

FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge including an electrophotographic photosensitive member.

Reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is rotationally driven at a predetermined peripheral speed in the direction of an arrow about a shaft 2. The surface of the electrophotographic photosensitive member 1 is charged to a predetermined positive or negative potential by the charging means 3. Although the roller charging method using the roller type charging member is shown in the figure, a charging method such as a corona charging method, a proximity charging method, or an injection charging method may be adopted.

The surface of the charged electrophotographic photosensitive member 1 is irradiated with exposure light 4 from an exposure means (not shown) to form an electrostatic latent image corresponding to the target image information. The electrostatic latent image formed on the surface of the electrophotographic photosensitive member 1 is developed with the toner contained in the developing means 5, and the toner image is formed on the surface of the electrophotographic photosensitive member 1.

The toner image formed on the surface of the electrophotographic photosensitive member 1 is transferred to the transfer material 7 by the transfer means 6. The transfer material 7 to which the toner image is transferred is conveyed to the fixing means 8, undergoes the toner image fixing process, and is printed out of the electrophotographic apparatus.

The electrophotographic apparatus may have a cleaning means 9 for removing deposits such as toner remaining on the surface of the electrophotographic photosensitive member 1 after transfer. Further, a so-called cleanerless system may be used in which the above-mentioned deposits are removed by a developing means or the like without separately providing a cleaning means.

The electrophotographic apparatus may have a static elimination mechanism for statically eliminating the surface of the electrophotographic photosensitive member 1 with preexposure light 10 from a preexposure means (not shown). Further, in order to attach / detach the process cartridge of the present invention to / from the main body of the electrophotographic apparatus, a guide means 12 such as a rail may be provided.

The electrophotographic photosensitive member of the present invention can be used for laser beam printers, LED printers, copiers, facsimiles, and multifunction devices thereof.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the description of the following examples, the term "part" is based on mass unless otherwise specified.

(Example 1)
As a support (conductive support), an aluminum cylinder having a length of 357.5 mm, a thickness of 0.7 mm, and an outer diameter of 30 mm was prepared.

Next, 100 parts of titanium oxide particles having an average primary particle size of 6 nm (trade name: AMT100, manufactured by TAYCA CORPORATION, specific surface area of 300 m ² / g) were stirred and mixed with 500 parts of toluene. To this, 5 parts of isobutyltrimethoxysilane (manufactured by Dow Toray Co., Ltd.) and glass beads having a diameter of 1 mm were added, and the mixture was stirred with a paint shaker disperser for 6 hours. The glass beads were removed with a filter, toluene was distilled off under reduced pressure, heat-dried at 130 ° C. for 6 hours, and then pulverized to obtain surface-treated titanium oxide particles.

The specific surface area of the surface-treated titanium oxide particles was measured with a BET specific surface area measuring device (Macsorb HM model 1210 manufactured by Mountech Co., Ltd.). When measured using a nitrogen gas as the carrier gas and a mixed gas of nitrogen: helium = 3: 7 as the adsorbed gas, ^{it was 310 m 2} / g.

Next, 20 parts of a polyamide resin (trade name: CM8000, manufactured by Toray Industries, Inc.) was dissolved in a mixed solution of 100 parts of methanol and 100 parts of methoxypropanol.

To this solution, 40 parts of the surface-treated titanium oxide particles and 1 part of 1,2-dihydroxyanthraquinone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added as an electron accepting substance.

This was dispersed in a sand mill device using glass beads having a diameter of 0.8 mm in an atmosphere of 23 ± 3 ° C. for 8 hours. After dispersion, 0.01 part of silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Co., Ltd.) was added.

Further, two parts of crosslinked polymethyl methacrylate (PMMA) particles (trade name: TECHPOLYMER SSX-103, manufactured by Sekisui Plastics Co., Ltd.) were added and stirred to prepare a coating liquid for an undercoat layer.

The coating liquid for the undercoat layer was immersed and coated on the aluminum cylinder to form a coating film, and the obtained coating film was dried at 100 ° C. for 10 minutes to form an undercoat layer having a film thickness of 10 μm.

Next, two parts of crystalline hydroxygallium phthalocyanine crystals (charge generators) having strong peaks at 7.4 ° and 28.2 ° at a Bragg angle of 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction, and bisphenol. 40 parts of Z-type polycarbonate resin (trade name: Z400, manufactured by Mitsubishi Engineering Plastics Co., Ltd.), 30 parts of compound (A) represented by the following formula as a charge transporting substance, 3,3', 5 as an electron transporting substance. , 5'-tetra-tert-butyl-4,4'-diphenoquinone (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and silica particles surface-treated with hexamethyldisilazane (average particle size 12 nm, Nippon Aerodil Co., Ltd.) ), 140 parts of tetrahydrofuran and 140 parts of o-xylene as a solvent were placed in a sand mill using glass beads having a diameter of 1 mm and subjected to dispersion treatment for 4 hours.

The coating liquid for a photosensitive layer was immersed and coated on the undercoat layer to form a coating film, and the obtained coating film was dried at 110 ° C. for 50 minutes to form a photosensitive layer having a film thickness of 25 μm.

[Evaluation]
As the evaluation device, a copying machine (trade name: IR-ADV C5560F) manufactured by Canon Inc. was modified and used. The charging means was a rubber roller type contact charging (charging roller) to which a direct current was applied. The exposure means is laser image exposure, and the developing means is a one-component magnetic negative toner non-contact developing system. The transfer means was a belt-type contact transfer system, and the cleaning means used a cleaner in which the rubber blade was set in the counter direction with respect to the rotation direction of the photoconductor. As the pre-exposure means, pre-exposure using an LED was used. The electrophotographic photosensitive members of Examples 1 to 3 were installed in this evaluation device, respectively.

The evaluation device was installed in an environment with a temperature of 23 ° C. and a humidity of 50% RH.

An A3 size halftone image was output, visually observed, and evaluated according to the following evaluation criteria.
A: No image defect B: Minor image defect C: Image defect

Next, 50,000 sheets were continuously endured on an A4 size test chart having an image ratio of 5% while keeping the initially set charging conditions and exposure conditions. After the endurance, an A3 size halftone image was output, visually observed, and evaluated.

The results are shown in Table 1.

(Example 2)
In Example 1, the titanium oxide particles were surface-treated with silica and alumina (trade name: TKP101, manufactured by TAYCA CORPORATION, specific surface area of 280 m ² / g), and the isobutyltri was the same as in Example 1. The surface was treated with methoxysilane. The specific surface area of the surface-treated titanium oxide particles was measured and found to be 250 m ² / g. The electrophotographic photosensitive member of Example 2 was prepared and evaluated in the same manner as in Example 1.

The results are shown in Table 1.

(Example 3)
In Example 2, the amount of isobutyltrimethoxysilane added was changed to 10 parts, and the surface treatment was performed in the same manner as in Example 1. The specific surface area of the surface-treated titanium oxide particles was measured and found to be 200 m ² / g. Further, an electrophotographic photosensitive member of Example 3 was prepared and evaluated in the same manner as in Example 1 except that the electron transporting substance of the photosensitive layer was changed to 9-fluorenone (manufactured by Tokyo Chemical Industry Co., Ltd.). It was.

The results are shown in Table 1.

(Example 4)
In Example 1, the electrophotographic photosensitive member of Example 4 was prepared and evaluated in the same manner as in Example 1 except that the amount of surface-treated titanium oxide particles added to the undercoat layer was changed to 20 parts. It was. The results are shown in Table 1.

(Example 5)
In Example 1, the electrophotographic photosensitive member of Example 5 was prepared and evaluated in the same manner as in Example 1 except that the amount of titanium oxide particles added to the undercoat layer was changed to 85 parts. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, titanium oxide particles having an average primary particle size of 10 nm (trade name: MT-05, manufactured by TAYCA CORPORATION, 150 m ² / g) were used, and surface treatment was performed in the same manner as in Example 1. It was. The specific surface area of the surface-treated titanium oxide particles was measured and found to be 170 m ² / g. An electrophotographic photosensitive member of Comparative Example 2 was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
An electrophotographic photosensitive member of Comparative Example 2 was prepared and evaluated in the same manner as in Example 2 except that the electron-accepting substance of the undercoat layer was not added in Example 1. The results are shown in Table 1.

1 Electrophotographic photosensitive member 2 axes 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Guide means

Claims (5)

It has a support, an undercoat layer, and a photosensitive layer in this order.
The photosensitive layer is an electrophotographic photosensitive member which is a single-layer photosensitive layer containing a charge generating substance, a hole transporting substance, an electron transporting substance, silica particles, and a binder resin.
An electrophotographic photosensitive member, wherein the undercoat layer contains titanium oxide particles having a specific surface area of 200 m ² / g or more and ^{less than 400 m 2} / g, an electron-accepting substance, and a binder resin. The electrophotographic photosensitive member according to claim 1, wherein the content of the titanium oxide particles is 60% by mass or more and less than 80% by mass with respect to the total mass of the undercoat layer. The electrophotographic photosensitive member according to claim 1, wherein the electron-transporting substance is either a quinone compound or a cyclopentadienylidene compound. The electrophotographic photosensitive member according to any one of claims 1 to 3 is integrally supported with at least one means selected from the group consisting of charging means, developing means and cleaning means, and can be attached to and detached from the electrophotographic apparatus. A process cartridge characterized by being. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to any one of claims 1 to 3, a charging means, an exposure means, a developing means, and a transfer means.

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