JP2005148412A - Electrophotographic photoreceptor and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure stable properties for a functionally-separated photoreceptor using a combination of a specified charge generating material with a specified charge transportation material. <P>SOLUTION: A charge generating layer contains a compound of formula (I) and the specified charge generating material in a specified ratio. A charge transportation layer contains the specified charge transportation material, a hindered phenol antioxidant and a thio-ether antioxidant in a specified ratio. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photosensitive member such as a copying machine, a printer, and a facsimile, and an image forming apparatus using the same.

In an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile, a photoreceptor is uniformly charged, then a latent image is formed by exposure, and an image obtained by developing the latent image with toner or the like is formed on paper. Transfer to transfer material.
This photoreceptor contains a charge generating material that generates charges upon exposure.
As the charge generation material, organic pigments such as azo pigments and phthalocyanine pigments are used for general purposes.
As the azo pigment, those represented by the formula (I) having sensitivity in a wavelength region of a general-purpose semiconductor laser light wavelength of 700 to 800 nm are used.
In order to achieve the high sensitivity requirement, a charge transport material represented by the formula (III) is preferably used for the azo pigment.

However, when the azo pigment is subjected to an oxidizing action by a gas such as ozone or NOx generated in the charging process of the electrophotographic apparatus, there arises a problem that charging property is lowered or residual potential is increased by repeated use.
Similar problems also occur due to light fatigue caused by fluorescent light, exposure light, static elimination light, and the like.
As means for solving this problem, a photosensitive layer containing a hydroquinone compound and an organic phosphite compound (for example, see Patent Document 1) has been proposed. Further, a material in which a hydroquinone derivative and a phenolic antioxidant are contained in at least one of the charge generation layer and the charge transport layer has been proposed (see, for example, Patent Document 2). In addition, it has been proposed to contain a hydroquinone derivative and a hindered amine compound in the photosensitive layer (see, for example, Patent Document 3). In addition, it has been proposed to include a specific hindered phenol compound in the charge transport layer when using a trisazo pigment (see, for example, Patent Document 4). In addition, it has been proposed to include a specific organic sulfur compound in the charge transport layer (see, for example, Patent Document 5).

However, in these cases, a solution dissolved in dichloromethane is used as a coating liquid for producing the charge transport layer.
In general, chlorine-based solvents such as dichloromethane, monochlorobenzene, dichloroethane and the like have been used to easily dissolve polycarbonate-based resins that have a low boiling point and are widely used as resins for charge transport layers.
However, it has been clarified that these chlorinated solvents have many problems in terms of carcinogenicity and toxicity, and the use of these chlorinated solvents is restricted from the viewpoint of worker safety and environmental problems.
Alternative non-chlorine solvents include aromatic solvents such as toluene and xylene and cyclic ether solvents such as tetrahydrofuran, tetrahydropyran, and dioxolane. A cyclic ether solvent is preferably used because it is suitable for coating productivity.
When these solvents are used, it is preferable to employ the means based on the above improvement proposal using a chlorinated solvent because the action of the contained antioxidant is too strong, and the increase in residual potential as a side effect and the decrease in sensitivity are extremely increased. Absent.

For example, it has been proposed that a photosensitive layer contains a phenolic antioxidant and an organic sulfur compound (see, for example, Patent Document 6), and a photosensitive layer using tetrahydrofuran and cyclohexanone as a solvent is used. However, in this case, the photosensitive layer is a single layer type positively charged photosensitive member having a charge generating material and a charge transporting material in a single layer. What is a functional separation type photosensitive member in which a charge transporting layer is laminated on a charge generating layer? Different.
In addition, it has been proposed to contain a hindered phenol compound and an organic sulfur-based antioxidant using a cyclic ether solvent (see, for example, Patent Document 7). However, a sufficient effect cannot be obtained in the combination of the charge generation material and the charge transport material used in the present invention.
In addition, it has been proposed to improve resistance to gases such as ozone and NOx by mixing a trisazo pigment with a disazo pigment (see, for example, Patent Document 8). However, although resistance to oxidizing substances such as ozone and NOx is improved, it is not sufficient for electrical deterioration in long-term use in an electrophotographic apparatus. In addition, the publication describes that the mixing ratio of the trisazo pigment and the disazo pigment can be used at an arbitrary ratio. However, the storage stability of the solution is poor and it is necessary to dispose it in a short life. In this case, image problems such as background stains and uneven density have occurred.

As described above, many of the conventional improvement means are carried out on a layer made of a coating solution using a chlorinated solvent, and when this is applied to a cyclic ether solvent, a large residual charge is obtained. Increases and decreases sensitivity.
On the other hand, it has been proposed to improve this by adding an organic sulfur-based antioxidant. However, the combination of the charge generating material and the charge transporting material of the present invention that exhibits high sensitivity characteristics provides a sufficient improvement effect. However, the chargeability and sensitivity are reduced by repeated use.
Further, it can be improved by containing a hindered phenol antioxidant, but depending on the content, improvement in properties is insufficient. In particular, chargeability may be reduced at high temperatures and high humidity.
As a charge generation material, it has also been proposed to improve resistance to NOx and ozone by mixing a trisazo pigment with a disazo pigment, but the effect of suppressing the decrease in chargeability is insufficient in repeated use in an actual electrophotographic apparatus. It is.
Further, when the ratio of the trisazo pigment is large, the sensitivity is sufficient, but there is a problem in that the liquidity of the coating liquid is poor and uneven coating tends to occur, resulting in uneven image density.
On the contrary, when there are many disazo pigments, there are problems that the sensitivity is slow and sufficient image density cannot be obtained, or that background stains are generated due to a decrease in chargeability due to light fatigue.

Japanese Patent No. 2936511 JP 2000-89490 A JP-A-6-75395 JP-A-7-168380 JP 7-295250 A Japanese Patent Laid-Open No. 9-106085 JP 2001-109173 A JP-A-6-49433

  The present invention solves the above problems, that is, when a charge transport layer formed by using a cyclic ether solvent is formed on a function-separated type photoreceptor by a combination of a specific charge generation material and a charge transport material. It is an object of the present invention to provide an electrophotographic photosensitive member that has stable characteristics with no decrease in chargeability even after repeated use over a long period of time and that does not deteriorate chargeability in a high-temperature and high-humidity environment.

  The above-mentioned problem is (1) in the electrophotographic photoreceptor having a photosensitive layer in which a charge generating layer containing at least a charge generating material and a charge transporting layer containing a charge transporting material are sequentially laminated on a conductive support. The charge generation layer contains the charge generation material represented by the formulas (I) and (II) at a weight ratio of 1 / 1.5 to 1/8, and the charge transport layer is a cyclic ether-based material. The solvent contains at least a binder resin, a charge transport material represented by the formula (III), a hindered phenol antioxidant and a thioether antioxidant, and contains the hindered phenol antioxidant and the thioether antioxidant. An electrophotographic photoreceptor having a ratio of 1/1 to 1/3;

（式中、Ａはフェノール性ＯＨ基を有するカプラー残基を表わす。）

(In the formula, A represents a coupler residue having a phenolic OH group.)

（式中、Ａはフェノール性ＯＨ基を有するカプラー残基を表わす。）

(In the formula, A represents a coupler residue having a phenolic OH group.)

（式中、Ｒ_１，Ｒ_２は水素原子、アルキル基、アリール基を表わし、環を形成しても良い。Ａｒ_１はアリーレン基または複素環基を表わす。Ａｒ_２，Ａｒ_３はアルキル基、アリール基、複素環基を表わす。）」、（２）「少なくとも感光体表面を帯電する帯電手段、潜像を形成する露光手段、潜像をトナーにより現像する現像手段、現像されたトナー像を転写材に転写する転写手段を有する画像形成装置において、前記感光体が前記第（１）項に記載の感光体であることを特徴とする画像形成装置」、（３）「前記第（１）項に記載の電子写真用感光体と、帯電手段、現像手段、クリーニング手段、トナー供給手段より選ばれる少なくとも一つの手段を一体に支持し、画像形成装置本体に着脱自在であることを特徴とする電子写真用カートリッジ」、（４）「前記第（３）項に記載の電子写真用カートリッジを搭載することを特徴とする画像形成装置」によって解決される。

(Wherein R ₁ and R ₂ represent a hydrogen atom, an alkyl group, or an aryl group, and may form a ring; Ar ₁ represents an arylene group or a heterocyclic group; Ar ₂ and Ar ₃ represent an alkyl group; Represents an aryl group or a heterocyclic group.) ”, (2)“ Charging means for charging at least the surface of the photoreceptor, exposure means for forming a latent image, developing means for developing the latent image with toner, and developing the developed toner image An image forming apparatus having transfer means for transferring to a transfer material, wherein the photoconductor is the photoconductor described in item (1) above, (3) “the first (1)” The electrophotographic photosensitive member described in the above section and at least one means selected from a charging means, a developing means, a cleaning means, and a toner supply means are integrally supported and detachably attached to the image forming apparatus main body. Car for electrophotography "Tredge", (4) "An image forming apparatus comprising the electrophotographic cartridge described in the item (3)".

  According to the present invention, when a charge transport layer formed using a cyclic ether solvent is formed on a function-separated type photoconductor by a combination of a specific charge generation material and a charge transport material, the chargeability can be maintained even in long-term repeated use. Provided is an electrophotographic photosensitive member that is stable and has no deterioration, and in which the chargeability does not decrease in a high-temperature and high-humidity environment, particularly when a cyclic ether solvent is used as a coating solution for the charge transport layer. By using a hindered phenolic antioxidant and a thioether antioxidant in a ratio of 1/1 to 1/3, an excellent effect is achieved that excellent characteristics can be maintained even in a high temperature and high humidity environment.

Hereinafter, the photoconductor used in the present invention will be described in detail.
FIG. 2 is a diagram showing the layer structure of the photoreceptor used in the present invention.
On the conductive support (21), an intermediate layer (22), a charge generation layer (23), and a charge transport layer (24) are sequentially laminated.
As the conductive support (21), as the conductive support, one having a volume resistance of 10 ¹⁰ Ω · cm or less, such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, etc. Metal, tin oxide, indium oxide and other metal oxides by vapor deposition or sputtering, coated with film or cylindrical plastic, paper, or a plate of aluminum, aluminum alloy, nickel, stainless steel, or the like After forming the tube by a method such as extruding and drawing, it is possible to use a tube that has been subjected to surface treatment such as cutting, superfinishing or polishing.
Further, endless nickel belts and endless stainless steel belts disclosed in JP-A-52-36016 can also be used as the conductive support (21).
In addition to the above, a conductive powder dispersed in a suitable binder resin and coated on the support can be used as the conductive support (21) of the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, or metal oxide such as conductive titanium oxide, conductive tin oxide, and ITO. Examples include powder.

  The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin.

  Such a conductive layer dissolves and disperses these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, 2-butanone, toluene, xylene, cyclohexanone, methyl ethyl ketone, methanol, 1-butanol and the like. And can be provided by coating.

  Furthermore, a conductive layer is provided on a suitable cylindrical substrate by a heat-shrinkable tube containing the conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon. Can also be used favorably as the conductive support (21) of the present invention.

The intermediate layer (22) contains a binder resin together with titanium oxide. Examples of the resin include polyvinyl alcohol, casein, sodium polyacrylate, copolymer nylon, methoxymethylated nylon, and other thermoplastic resins, polyurethane. And thermosetting resins such as melamine, epoxy, alkyd, phenol, butyral, and unsaturated polyester resin.
Furthermore, the ratio P / R of titanium oxide (P) and binder resin (R) contained in the intermediate layer of the present invention is preferably in the range of 0.9 / 1 to 2/1 by volume ratio.
When the P / R ratio of the intermediate layer is less than 0.9 / 1, the characteristics of the intermediate layer depend on the characteristics of the binder resin, and the characteristics of the photoreceptor greatly change due to changes in temperature and humidity and repeated use. . Further, when the P / R ratio exceeds 2/1, voids increase in the intermediate layer, adhesion with the charge generation layer decreases, and when it exceeds 3/1, air accumulates. When the photosensitive layer is applied and dried, it causes bubbles and causes application defects.

In addition to titanium oxide, fine powder pigments of metal oxides such as aluminum oxide, silica, zirconium oxide, tin oxide and indium oxide may be added to the intermediate layer (22) in order to prevent moire and reduce residual potential. good. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, a titanyl chelate compound, a zirconium chelate compound, a titanyl alkoxide compound, and an organic titanyl compound can also be used as the intermediate layer (22) of the present invention.
These intermediate layers (22) can be formed using an appropriate solvent, dispersion, and coating method. In addition, in the intermediate layer (22) of the present invention, Al ₂ O ₃ is provided by anodic oxidation, organic matter such as polyparaxylylene, SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO _2, etc. Those provided with an inorganic material by a vacuum thin film forming method can also be used favorably.
The film thickness of the intermediate layer (22) is suitably from 0 to 20 μm.
If necessary, a resin such as copolymer nylon or methoxymethylated nylon may be further laminated thereon.

  For the charge generation layer (23), a trisazo pigment represented by the following formula (I) having sensitivity in a wavelength range of a general-purpose semiconductor laser of 700 to 800 nm is used as the charge generation material.

（式中、Ａはフェノール性ＯＨ基を有するカプラー残基を表わす。）
以下には、その具体例を示す。

(In the formula, A represents a coupler residue having a phenolic OH group.)
Specific examples are shown below.

  The pigment is dispersed in a suitable solvent such as 2-butanone, cyclohexanone, tetrahydrofuran, methanol, or the like by a dispersion method such as a bead mill, a ball mill, or a sand mill. A solution in which a resin such as a polyester resin, a polyvinyl acetal resin, a polyvinyl butyral resin, or a fluororesin is dissolved as a binder is applied and dried on the intermediate layer (22) as a coating liquid.

Further, by mixing the above trisazo pigment with a disazo pigment represented by the following formula (II), an improvement in gas resistance, an improvement in sensitivity, an improvement in coating property, and the like can be obtained.
The mixing ratio is preferably (I) / (II) = 1 / 1.5 to 1/8.
When the ratio of (I) is large, the chargeability decreases due to long-term use and the resistance decreases due to oxidizing substances such as ozone and NOx. In addition, liquidity is poor and unevenness is likely to occur during coating. The coating unevenness appears as the density unevenness of the image as it is. However, this is not to say that the pigment ratio is as described above, and the liquid viscosity is preferably such that the viscosity at 22 ° C. is 2.0 to 5.0 mPa · s. If it is less than 2.0 mPa · s, unevenness is likely to occur, and if it exceeds 5.0 mPa · s, the viscosity is too high, resulting in unevenness due to uneven circulation in the coating apparatus, and the coating speed is slowed, resulting in productivity. It will be inferior.
Such a viscosity varies depending on the pigment ratio, pigment type, solvent type, solid content, dispersion method, and the like, and is set so that the above-described appropriate viscosity is obtained. In measuring the viscosity, a measuring device such as an E-type viscometer is used.
As shown in FIG. 3, a conical rotor (31) is arranged in a cylindrical cell (32). A solution (33) to be measured is injected into a portion sandwiched between the cell and the rotor. When the rotor is rotated, resistance due to the viscosity of the solution is generated, and this is measured as the viscosity.

  On the other hand, when the ratio of (II) is too large, the decrease in chargeability due to light fatigue of the static elimination light increases. In addition, light fatigue due to white light such as fluorescence also increases, and light fatigue occurs when exposed to a fluorescent lamp during replacement, etc., resulting in scumming on the first sheet or excessive density overall. Problems occur. In mixing, it is preferable to mix and pulverize at the time of milling dispersion. By simultaneously milling, a more sensitive and stable characteristic can be obtained.

（式中、Ａはフェノール性ＯＨ基を有するカプラー残基を表わす。）

(In the formula, A represents a coupler residue having a phenolic OH group.)

  Specific examples of the disazo pigment are shown below.

  In the charge transport layer (24), a triphenylamine compound represented by the formula (III) is used to achieve high sensitivity by combination with the charge generation material.

（式中、Ｒ_１，Ｒ_２は水素原子、アルキル基、アリール基を表わし、環を形成しても良い。Ａｒ_１はアリーレン基または複素環基を表わす。Ａｒ_２，Ａｒ_３はアルキル基、アリール基、複素環基を表わす。）

(Wherein R ₁ and R ₂ represent a hydrogen atom, an alkyl group, or an aryl group, and may form a ring; Ar ₁ represents an arylene group or a heterocyclic group; Ar ₂ and Ar ₃ represent an alkyl group; Represents an aryl group or a heterocyclic group.)

  Specific examples are shown below.

Examples of the binder resin used for the charge transport layer (24) include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate. Copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy Thermoplastics such as resins, melamine resins, urethane resins, phenol resins, alkyd resins, and various polycarbonate copolymers described in JP-A-5-15158250 and JP-A-6-51544; Thermosetting resins.
Polycarbonate resins are preferred in terms of electrostatic characteristics such as sensitivity and abrasion resistance.
In particular, those having a viscosity average molecular weight of 50,000 or more are preferable from the viewpoint of wear resistance.
The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin.
The thickness of the charge transport layer is preferably about 5 to 50 μm.
Moreover, it is preferable to contain a hindered phenolic antioxidant and a thioether antioxidant for further improvement of characteristics. As a phenolic antioxidant, a commercially available general one can be used.
Below are some typical examples.

  On the other hand, the following are mentioned as a thioether type | system | group antioxidant.

（式中、ｎは５〜２０の整数を表わす。）

(In the formula, n represents an integer of 5 to 20.)

Among these, those that can obtain a favorable effect in combination with the above-described hindered phenol antioxidant can be appropriately selected and used.
Moreover, it is not limited to these.
Two or more of these may be mixed.
In this invention, it is necessary to contain a hindered phenol type and a thioether type antioxidant simultaneously. By containing both, the effect which cannot be acquired independently is acquired, and a subject can be solved.
By containing a hindered phenol-based antioxidant, the chargeability is improved and the oxidation-resistant gas is improved. However, if an additive amount for fully exhibiting the effect is contained, the residual potential accumulates due to repeated use, and the sensitivity is greatly reduced.
The above problem is improved by using a thioether antioxidant together.
The content ratio of these hindered phenol antioxidants and thioether antioxidants is preferably 1/1 to 1/3. When there are more hindered phenolic antioxidants than thioether type antioxidants, it is unpreferable because charging property will fall in a high-temperature, high-humidity environment.
On the other hand, if the ratio of the thioether-based antioxidant exceeds the above ratio, the sensitivity is greatly lowered, which is not preferable.
Moreover, a ultraviolet absorber, a hindered amine compound, etc. can also be used together as needed.
The total amount of each antioxidant added is 0.5 to 10% by weight, preferably 1 to 5% by weight, based on the total solid content.
Moreover, the addition amount of the antioxidants (IV) and (V) with respect to the weight of the charge transport material (III) is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the charge transport material (III). More preferably, it is 1 to 10 parts by weight.

Each of these constituent materials is applied with a coating solution dissolved in an appropriate organic solvent, but from the environmental viewpoint, chlorinated solvents such as dichloromethane, chloroform, monochlorobenzene, trichloroethane, and trichloromethane are avoided. .
Examples of the cyclic ether solvent include tetrahydrofuran, tetrahydropyran, 1,4-dioxane, dioxolane and the like.
Moreover, you may add smoothing agents, such as silicone oil, and lubricants, such as a Teflon microparticle, as needed. Moreover, other general antioxidant can also be used together.

Next, a general electrophotographic apparatus will be described with reference to FIG.
FIG. 1 shows a schematic view of a commonly used image forming apparatus.
Here, after the photoreceptor (11) is charged to a desired potential by the charger (12), a latent image is formed by exposure (13), and a toner image is formed by the developer (14).
The toner image is transferred to a transfer material (paper) (15) by a transfer means to which a bias is applied.
The toner image remaining on the photoreceptor without being transferred is cleaned by the cleaning member (17). The charge removal member (18) initializes the remaining charge and completes one cycle.
In this process, as the charging member (12) and the transfer member (16), as shown in the figure, a proximity discharge type charging roller in which a roller-like member is arranged in contact or non-contact with the photoreceptor (11) is widely used. ing. Although the amount of ozone generated is small in this method, it is a discharge phenomenon at a very close distance of several tens to several hundreds of μm from the surface of the photoconductor, so that the photoconductor surface is seriously damaged. For example, the oxidation of the resin constituting the photosensitive layer, the charge transport layer, etc. is promoted, and the wear resistance increases due to the lower molecular weight of the resin, the residual potential increases due to the oxidation of the charge transport layer, the sensitivity decreases, the chargeability decreases, etc. The influence of is very large. In particular, the influence of the bias applied to the charging roller is greater when AC is superimposed on DC than when only DC is applied.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In these examples, in order to clearly show the comparison, the same raw material components are used as much as possible.
(Example 1)
70 parts by weight of titanium oxide (CREL: manufactured by Ishihara Sangyo), 15 parts by weight of alkyd resin (Beckolite M6401-50-S (solid content 50%): manufactured by Dainippon Ink & Chemicals), melamine resin (Super Becamine L-121) -60 (solid content 60%): Dai Nippon Ink Chemical Co., Ltd.) 10 parts by weight, a mixture of 100 parts by weight of methyl ethyl ketone was dispersed for 72 hours with a ball mill to prepare an intermediate layer coating solution, diameter 30 mm, length It apply | coated on the 340 mm aluminum cutting drum, and it dried at 130 degreeC for 20 minutes, and produced the intermediate | middle layer with a film thickness of 3 micrometers.
Next, 5 parts by weight of a trisazo pigment having the following structural formula (A) and 10 parts by weight of a disazo pigment having the following structural formula (B) are dispersed in 20 parts by weight of cyclohexanone with a ball mill for 5 days, and then polyvinyl butyral resin (XYHL; Union) Carbide Co.) was diluted with a mixed solvent consisting of 2 parts by weight, 100 parts by weight of methyl ethyl ketone and 300 parts by weight of cyclohexanone to prepare a coating solution for charge generation layer.
It apply | coated on the said intermediate | middle layer with this coating liquid, and it dried at 130 degreeC for 20 minutes, and formed the charge generating layer with a film thickness of 0.2 micrometer.
Next, 70 parts by weight of a charge transport material represented by the following structural formula (C), 100 parts by weight of polycarbonate (Z type; viscosity average molecular weight 50000), 0.02 weight of silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) 2 parts by weight of the structural formula (IV) -1 compound and 2 parts by weight of the compound of formula (V) -3 (n = 18) are dissolved in 800 parts by weight of tetrahydrofuran to prepare a coating solution for a charge transport layer. did. This was applied onto the charge generation layer and dried at 130 ° C. for 20 minutes to form a 28 μm-thick charge transport layer, thereby preparing an electrophotographic photoreceptor provided in the electrophotographic image forming apparatus of the present invention.
Each of the intermediate layer, the charge generation layer, and the charge transport layer was applied by dip coating.

(Examples 2 and 3, Comparative Examples 1 and 2)
Example 1 was the same as Example 1 except that compound (IV) -1 and compound (V) -3 (n = 18) were used in the ratios shown in the following table.

(Example 4, Comparative Examples 3 and 4)
Example 1 except that the charge generation material (I) (= charge generation material (A)) and charge generation material (II) (= charge generation material (B)) in Example 1 are in the ratios shown in the following table. And the same.

  Each of the above photoreceptors was mounted on a Ricoh copier imagioMF2200, and the dark part potential and the bright part potential were measured in an environment of 25 ° C. and 50% and 30 ° C. and 85%. In addition, a test image was output to check whether there was any abnormality. The results are shown in the table below.

  As is apparent from the examples, the constitution of the present invention, that is, the charge generation layer contains the formula (I) and the formula (II) at a ratio of 1 / 1.5 to 1/8, and the charge transport layer coating solution Even in the case of using a cyclic ether solvent, the combination of a hindered phenol antioxidant and a thioether antioxidant in a ratio of 1/1 to 1/3 provides excellent characteristics even in a high temperature and high humidity environment. Can be maintained.

It is a figure explaining the electrophotographic apparatus used by this invention. It is a figure which shows the laminated constitution of the photoreceptor used for this invention. It is explanatory drawing of an E-type viscosity meter.

Explanation of symbols

11; photoconductor 12; charging roller 13; writing light 14; developing unit 15; transfer paper 16; transfer roller 17; cleaning unit 18; neutralizing lamp 21; conductive support 22; Transport layer 31; rotor 32; cell 33; measurement solution

Claims (4)

In an electrophotographic photosensitive member having a photosensitive layer in which a charge generating layer containing at least a charge generating material and a charge transporting layer containing a charge transporting material are sequentially laminated on a conductive support, the charge generating layer has the formula (I) And the charge generation material represented by (II) at a weight ratio of 1 / 1.5 to 1/8, and the charge transport layer comprises at least a binder resin in a cyclic ether solvent, represented by formula (III) The charge transport material shown, a hindered phenolic antioxidant and a thioether antioxidant are contained, and the content ratio of the hindered phenolic antioxidant and the thioether antioxidant is 1/1 to 1/3. An electrophotographic photosensitive member characterized by the above.

(In the formula, A represents a coupler residue having a phenolic OH group.)

(In the formula, A represents a coupler residue having a phenolic OH group.)

(Wherein R ₁ and R ₂ represent a hydrogen atom, an alkyl group, or an aryl group, and may form a ring. Ar ₁ represents an arylene group or a heterocyclic group. Ar ₂ and Ar ₃ represent an alkyl group, Represents an aryl group or a heterocyclic group.) An image forming apparatus comprising: a charging unit that charges at least a surface of a photoconductor; an exposure unit that forms a latent image; a developing unit that develops the latent image with toner; and a transfer unit that transfers the developed toner image to a transfer material. An image forming apparatus, wherein the body is the photoreceptor according to claim 1. The electrophotographic photosensitive member according to claim 1 and at least one unit selected from a charging unit, a developing unit, a cleaning unit, and a toner supply unit are integrally supported and detachable from the main body of the image forming apparatus. An electrophotographic cartridge. An image forming apparatus comprising the electrophotographic cartridge according to claim 3.

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