JP4354969B2 - Electrophotographic photosensitive member and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor and an image forming apparatus. In particular, by containing an electron transport agent having a specific structure in the photosensitive layer, an electron that can maintain excellent sensitivity even when used repeatedly and can effectively suppress exposure memory. The present invention relates to a photographic photosensitive member and an image forming apparatus using the same.

Conventionally, as an electrophotographic photosensitive member used in an image forming apparatus, a charge generating agent for generating a charge by light irradiation, a charge transporting agent for transporting the generated charge, and these substances are dispersed. An organic photoreceptor containing a binder resin for forming a layer is widely used.
An image forming apparatus used for such an organic photoconductor includes a charging unit for charging the surface of the photoconductor, an exposure unit for irradiating the charged surface with light to form a latent image, and the latent image. An image forming process is employed in which a developing unit for developing a toner image to form a toner image and a transfer unit for transferring the toner image onto printing paper are sequentially arranged.
However, when such an image forming process is repeatedly performed, there has been a problem that the sensitivity is lowered due to light fatigue, or an exposure memory is generated due to accumulation of residual charges in the photosensitive layer.

  Therefore, in order to solve such a problem, an electrophotographic photoreceptor using an azo compound represented by the following general formula (23) as an electron transporting agent in a positively charged electrophotographic photoreceptor has been proposed ( For example, Patent Document 1).

(In the general formula (23), R ¹ and R ² each independently have a halogen atom, an optionally substituted alkyl group or alkoxy group having 1 to 8 carbon atoms, an arylalkyl group, or a substituent. An aryl group which may be substituted, a residue for forming a ring, R ³ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group which may have a substituent, A ¹ is an oxygen atom, or = CR ⁴ R ⁵ (wherein R ⁴ and R ⁵ are each a cyano group or an alkoxycarbonyl group), m represents an integer of 0 to 4, n represents an integer of 0 to 5, and m and n are 2 or more. Two or more R ¹ and R ² may be the same or different.)
JP 2000-199979 (Claims)

However, the azo compound represented by the general formula (23) in Patent Document 1 has insufficient electron transport ability, and particularly in a single-layer electrophotographic photoreceptor, there is a problem that sensitivity is likely to be lowered. .
Further, the electrophotographic photosensitive member of Patent Document 1 is limited to a positively charged electrophotographic photosensitive member, and no mention is made of a case where a laminated electrophotographic photosensitive member is employed. Therefore, in the multilayer electrophotographic photosensitive member, residual charges are accumulated at the interface between the charge generation layer and the intermediate layer or between the intermediate layer and the substrate, and as a result, an exposure memory is generated due to the accumulation of the residual charge. The problem of being left unresolved.

Therefore, as a result of intensive studies, the present inventors have found that in a photosensitive layer of an electrophotographic photosensitive member (including a charge generation layer in the case where a laminated electrophotographic photosensitive member is employed, the same applies hereinafter). The present inventors have found that by including an electron transfer agent having a specific structure, excellent sensitivity can be maintained even when used repeatedly, and exposure memory can be effectively suppressed, and the present invention is completed. It has been made.
That is, the present invention can maintain excellent sensitivity even when used repeatedly by efficiently transporting electrons generated in the photosensitive layer to the substrate side or the surface side of the photosensitive layer. An object of the present invention is to provide an electrophotographic photosensitive member capable of effectively suppressing exposure memory.

  According to the present invention, there is provided an electrophotographic photosensitive member provided with a photosensitive layer containing at least a charge generating agent, an electron transporting agent, and a binder resin on a substrate directly or via an intermediate layer, An electrophotographic photosensitive member is provided in which the electron transfer agent is a compound represented by the following general formula (1), and the above-described problems can be solved.

(In General Formula (1), R < ¹ > -R < ⁴ > is an independent substituent, respectively, a hydrogen atom, a C1-C12 substituted or unsubstituted alkyl group, a C1-C12 substituted or unsubstituted Or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, Ar is a phenanthryl group or a pyrenyl group.

That is, by containing an azoquinone compound as an electron transporting agent represented by the general formula (1) in the photosensitive layer of the electrophotographic photosensitive member, the electrons generated from the charge generating agent by exposure can be efficiently removed from the substrate. Side or photosensitive layer surface side. Therefore, even when repeatedly used, excellent sensitivity can be maintained and the exposure memory can be effectively suppressed.
The electrophotographic photosensitive member can be either a single layer type or a laminated type. And when comprised as a single layer type electrophotographic photosensitive member, it is possible to maintain the sensitivity characteristics, which are said to be particularly liable to decrease, at an excellent level. Further, when it is configured as a multilayer electrophotographic photosensitive member, it effectively suppresses the generation of residual charges, which are known to occur easily at the interface between a plurality of layers or at the interface between a layer and a substrate. be able to.

In constituting the electrophotographic photoreceptor of the present invention, Ar in the general formula (1) is a phenanthryl group or a pyrenyl group.
By comprising in this way, not only the electron transport ability improves more, but crystallization can be suppressed effectively and formation of a photosensitive layer can be made easy.

In constructing the electrophotographic photosensitive member of the present invention, the electron mobility when the electric field strength is 5 × 10 ⁵ V / cm in the electron transport agent represented by the general formula (1) is 5 × 10 ^−10. A value within the range of ˜5 × 10 ⁻⁷ cm ² / V / sec is preferable.
With this configuration, electrons generated from the charge generating agent by exposure can be more efficiently transported to the substrate side or the photosensitive layer surface side.

In constituting the electrophotographic photosensitive member of the present invention, the photosensitive layer is a single-layer type photosensitive layer, and the content of the electron transfer agent represented by the general formula (1) is set in the single-layer type photosensitive layer. The value is preferably in the range of 0.5 to 60 parts by weight with respect to 100 parts by weight of the binder resin.
By configuring in this way, it is possible to maintain the sensitivity characteristic, which is said to be liable to be lowered when repeatedly used, as compared with the multilayer electrophotographic photosensitive member at an excellent level.
In addition, any positive or negative charge type can be adopted, and the layer structure of the electrophotographic photosensitive member can be simplified, thereby improving the productivity.

In constructing the electrophotographic photoreceptor of the present invention, the photosensitive layer is a multilayer photosensitive layer, and the electron transfer agent represented by the general formula (1) in the charge generation layer contained in the multilayer photosensitive layer. Is preferably set to a value in the range of 1 to 90 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer.
With such a configuration, it is possible to effectively suppress the generation of residual charges that are known to occur easily at the interface between a plurality of stacked layers or at the interface between a layer and a substrate.
Further, since there are various choices of photosensitive materials such as a charge generating agent and a charge transporting agent, there is an advantage that the degree of freedom in structural design is high.

Further, in constituting the electrophotographic photoreceptor of the present invention, the content of the electron transport agent represented by the general formula (1) in the charge transport layer contained in the multilayer photosensitive layer is determined by binding in the charge transport layer. The value is preferably in the range of 0.05 to 80 parts by weight with respect to 100 parts by weight of the resin.
By configuring in this way, in the charge generation layer, electrons generated from the charge generation agent can be quickly transported to the surface of the electrophotographic photosensitive member, and the generation of residual charges can be effectively suppressed. Thus, an electrostatic latent image can be formed.

  Further, in constituting the electrophotographic photosensitive member of the present invention, the binder resin contains a polycarbonate resin represented by the following general formula (2), and a value obtained by dividing the inorganic degree in the polycarbonate resin by the organic degree. The (I / O value) is preferably set to a value of 0.37 or more.

(In the general formula (2), a plurality of Ra and Rb are each an independent hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, and R ⁵ and R ⁶ is a different substituent, a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, W is a single bond or —O— or —CO—, and the repeating numbers k to 1 are independent of each other. The number of repetitions m and n is a molar ratio satisfying the relational expression of 0.05 <n / (n + m) <0.6.)

  By comprising in this way, the dispersibility and stability of a charge transfer agent can be improved. In addition, the stain resistance and wear resistance of the electrophotographic photosensitive member can be improved.

  In constituting the electrophotographic photosensitive member of the present invention, the binder resin may include a polycarbonate resin represented by the following general formulas (3) and (4), or a polycarbonate resin represented by either one of them. preferable.

(In General Formula (3), the plurality of substituents Rc are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms. The number o is an integer from 0 to 4.)

(In General Formula (4), a plurality of substituents Rd are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms. The number p is an integer from 0 to 4.)

  By comprising in this way, dispersibility and stability, such as a charge generating agent contained in a photosensitive layer, a charge transport agent, can be improved more. Further, the stain resistance and wear resistance of the electrophotographic photoreceptor can be further improved.

  In constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer preferably contains a compound represented by the following general formula (5) as an additive.

(In General Formula (5), R ^{7 to} R ¹⁶ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted carbon number 1 to 12. An alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, a hydroxyl group, R represents a substituted or unsubstituted alkylene group having 1 to 12 carbon atoms or an organic group containing a nitrogen atom, and n represents an integer of 0 to 3. )

  By comprising in this way, even if a contamination component adheres to the electrophotographic photosensitive member, the occurrence of cracks can be effectively prevented by the action of the compound represented by the general formula (5). Can do.

According to another aspect of the present invention, any one of the above-described electrophotographic photosensitive members is provided, and a charging unit, an exposing unit, a developing unit, and a transfer unit are disposed around the electrophotographic photosensitive member. An image forming apparatus.
That is, the electrophotographic photoreceptor mounted on the image forming apparatus of the present invention can maintain excellent sensitivity even when repeatedly used, and can effectively suppress the exposure memory. Therefore, the image forming apparatus of the present invention can stably produce a high-quality image even when it is repeatedly used.

[First Embodiment]
In the first embodiment of the present invention, an electrophotographic photoreceptor comprising a photosensitive layer containing at least a charge generating agent, an electron transporting agent, and a binder resin on a substrate directly or via an intermediate layer. In the electrophotographic photosensitive member, the electron transporting agent is represented by the general formula (1).
Hereinafter, the single layer type electrophotographic photosensitive member and the multilayer type electrophotographic photosensitive member according to the first embodiment will be specifically described.

1. Single Layer Type Electrophotographic Photoreceptor (1) Basic Configuration In constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer is preferably a single layer type.
The reason for this is that if the electrophotographic photosensitive member of the present invention is used repeatedly due to the action of an electron transporting agent having a specific structure described later, excellent sensitivity can be maintained, The exposure memory can be effectively suppressed. In particular, when the photosensitive layer is a single-layer type, the sensitivity characteristic, which is said to be liable to be lowered when repeatedly used, is maintained at an excellent level as compared with the multilayer electrophotographic photosensitive member. Because it can.
That is, by containing an electron transport agent having a specific structure in the photosensitive layer, electrons generated from the charge generation layer by exposure can be efficiently transported.
In addition, a single-layer type electrophotographic photosensitive member can be employed regardless of whether it is a positive or negative charge type, and the layer structure of the electrophotographic photosensitive member can be simplified, thereby improving productivity. is there.
Furthermore, because there are few interfaces between layers, the optical characteristics can be improved.

As a basic configuration of such a single layer type photoreceptor, as shown in FIG. 1A, a single layer type electrophotographic photoreceptor 10 is configured by providing a single photosensitive layer 14 on a substrate 12. is there.
The photosensitive layer 14 includes a coating solution in which a charge generator, an electron transport agent having a specific structure, a hole transport agent, a binder resin, and an additive are dissolved or dispersed in a predetermined solvent. It can be formed by coating on the substrate 12 and drying.
Further, as illustrated in FIG. 1B, a single-layer electrophotographic photosensitive member 10 ′ in which an intermediate layer 16 is formed between the photosensitive layer 14 and the substrate 12 can be used.
The thickness of the photosensitive layer 14 is usually a value in the range of 5 to 100 μm, preferably a value in the range of 10 to 50 μm.

(2) Base As the base 12 illustrated in FIG. 1, various materials having conductivity can be used. For example, metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass, and plastic materials on which the above-mentioned metals are deposited or laminated And glass coated with aluminum iodide, alumite, tin oxide, indium oxide, and the like.
Further, the shape of the substrate may be any of a sheet shape, a drum shape, or the like according to the structure of the image forming apparatus to be used. The substrate itself has conductivity, or the surface of the substrate has conductivity. If you do. Further, the substrate preferably has a sufficient mechanical strength when used.

In order to prevent the occurrence of interference fringes, the surface of the substrate should be roughened using a method such as etching, anodizing, wet blasting, sand blasting, rough cutting, or centerless cutting. Is preferred.
In addition, when anodic oxidation or the like is performed on the substrate, it may become non-conductive or semiconductor characteristics, but even in such a case, the substrate can be used as long as a predetermined effect is obtained. .

(3) Intermediate Layer Further, as shown in FIG. 1B, an intermediate layer 16 containing a predetermined binder resin may be provided on the base 12.
This is because the adhesion between the substrate and the photosensitive layer is improved, and the addition of a predetermined fine powder in the intermediate layer can scatter incident light and suppress the generation of interference fringes. It is. The fine powder is not particularly limited as long as it has light scattering properties and dispersibility, and examples thereof include white pigments such as titanium oxide, zinc oxide, zinc white, zinc sulfide, lead white, and lithopone. Inorganic pigments such as alumina, calcium carbonate, barium sulfate and the like, fluorine resin particles, benzoguanamine resin particles, styrene resin particles, and the like can be used.

Moreover, it is preferable that the film thickness of this intermediate layer is defined within a predetermined range. This is because if the intermediate layer is too thick, a residual potential is likely to be generated on the surface of the photoreceptor, which may cause a decrease in electrical characteristics. On the other hand, if the intermediate layer thickness is too thin, the unevenness of the substrate surface cannot be sufficiently relaxed, and the adhesion between the substrate and the photosensitive layer cannot be obtained.
Therefore, the thickness of the intermediate layer is preferably set to a value in the range of 0.1 to 50 μm, and more preferably set to a value in the range of 0.5 to 30 μm.

(4) Photosensitive layer (4) -1 Charge generator In addition, examples of the charge generator in the present invention include phthalocyanine pigments such as metal-free phthalocyanine and oxotitanyl phthalocyanine, perylene pigments, bisazo pigments, diketopyrrolopyrrole. Pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, pyrazolines Conventionally known charge generating agents such as organic photoconductors such as pigments and quinacridone pigments, and inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon can be used.
More specifically, it is more preferable to use phthalocyanine pigments (CGM-1 to CGM-4) represented by the following formulas (6) to (9).
This is because an electrophotographic photosensitive member having sensitivity in a wavelength region of 600 to 800 nm or more is required when used in a digital optical image forming apparatus such as a laser beam printer or a facsimile provided with a semiconductor laser as a light source. Because it becomes.
On the other hand, when used in an analog optical image forming apparatus such as an electrostatic copying machine equipped with a white light source such as a halogen lamp, an electrophotographic photosensitive member having sensitivity in the visible region is required. For example, perylene pigments and bisazo pigments can be suitably used.
Moreover, when the crystal | crystallization of titanyl phthalocyanine (CGM-2) represented by following formula (7) is used as a charge generation agent, it is preferable that this crystal | crystallization has a specific optical characteristic and a thermal characteristic.
That is, as an optical characteristic, the CuKα characteristic X-ray diffraction spectrum has a maximum peak at a Bragg angle 2θ ± 0.2 ° = 27.2 °, and as a thermal characteristic, in the differential scanning calorimetric analysis, the vaporization of adsorbed water occurs. In addition to the accompanying peak, it is preferable to have one peak in the range of 270 to 400 ° C.
The reason for this is that if the titanyl phthalocyanine crystal has such optical characteristics and thermal characteristics, even if it is immersed in an organic solvent for a long period of, for example, 7 days or longer, crystals into α-type crystals and β-type crystals This is because metastasis can be effectively suppressed. Therefore, it is possible to obtain a charge generation layer coating solution having excellent charge generation ability and storage stability, and stably producing an electrophotographic photoreceptor excellent in electrical characteristics and image characteristics using the coating liquid. Because it can.
In addition, it is more preferable that one peak appearing in the range of 270 to 400 ° C. other than the peak accompanying vaporization of the adsorbed water appears in the range of 290 to 400 ° C., and the range of 300 to 400 ° C. More preferably, it appears within.
A specific method for measuring the Bragg angle in the CuKα characteristic X-ray diffraction spectrum and a specific method for differential scanning calorimetry will be described in detail in Example 6 described later.

Further, the amount of the charge generating agent added is preferably set to a value in the range of 0.1 to 50 parts by weight with respect to 100 parts by weight of the binder resin described later.
This is because the charge generating agent can efficiently generate charges when the electrophotographic photosensitive member is exposed by setting the amount of the charge generating agent within this range. is there. That is, when the amount of the charge generating agent added is less than 0.1 parts by weight with respect to 100 parts by weight of the binder resin, the amount of charge generated is insufficient to form an electrostatic latent image on the photoreceptor. This is because there is a case of becoming. On the other hand, when the added amount of the charge generating agent exceeds 50 parts by weight with respect to 100 parts by weight of the binder resin, it may be difficult to uniformly disperse in the coating solution for the photosensitive layer. It is.
Therefore, it is more preferable that the amount of the charge generator added relative to 100 parts by weight of the binder resin is a value within the range of 0.5 to 30 parts by weight.

(4) -2 Electron Transfer Agent As the electron transfer agent used in the present invention, an azoquinone compound as an electron transfer agent represented by the general formula (1) is used.
The reason for this is that by using an electron transport agent having such a specific structure as the electron transport agent, electrons generated from the charge generating agent by exposure can be efficiently transported to the substrate side or the photosensitive layer surface side. This is because it can. Therefore, even when repeatedly used, excellent sensitivity can be maintained and the exposure memory can be effectively suppressed. In particular, when the photosensitive layer is a single-layer type, the sensitivity characteristic, which is said to be liable to be lowered when repeatedly used, is maintained at an excellent level as compared with the multilayer electrophotographic photosensitive member. Because it can.
That is, in a single layer type electrophotographic photosensitive member, since the photosensitive layer is a single layer, there are limitations on combinations of charge generating agents, charge transporting agents, binder resins, and the like, and it is difficult to select an optimum material. As a result, there was a problem that the sensitivity characteristics of the multi-layer electrophotographic photosensitive member are likely to deteriorate when used repeatedly.
However, in the case of the electron transporting agent represented by the general formula (1), in the azoquinone compound, the substituent represented by Ar in the general formula (1) is a phenanthryl group or a pyrenyl group. Electrons improve the electron transport ability in the molecule, suppress crystallization, and improve compatibility with the binder resin. As a result, electrons generated from the charge generating agent by exposure can be efficiently transported to the substrate side or the photosensitive layer surface side.
Therefore, even when repeatedly used, excellent sensitivity can be maintained.

  Specific examples of the electron transfer agent represented by the general formula (1) include compounds (ETM-1 and 2) represented by the following formulas (10) to (11).

In addition, the electron transport agent having the specific structure described above is characterized in that Ar in the general formula (1) is a phenanthryl group or a pyrenyl group.
The reason for this is that this configuration not only improves the electron transport ability, but also effectively suppresses crystallization and facilitates the formation of the photosensitive layer.
That is, the abundant π electrons can further improve the electron transport ability in the molecule, suppress crystallization, and further improve the compatibility with the binder resin.

Moreover, it is also preferable to use the compound generally used as an electron transport agent conventionally in combination with the electron transport agent represented by the general formula (1) described above.
The reason for this is that even when an electron transport agent having a specific structure and a conventional electron transport agent are mixed and used, as long as the mixing ratio is within a predetermined range, sufficient sensitivity characteristics are obtained. It is because it can exhibit etc.
That is, by using an electron transport agent having a specific structure and a conventional electron transport agent in combination, an electrophotographic photoreceptor having sufficient sensitivity characteristics and the like can be produced more economically. It is.
In addition, it is preferable to make the addition amount of the conventional electron transport agent into the value within the range of 10-100 weight part with respect to 100 weight part of electron transport agents which have a specific structure, The range of 20-80 weight part It is more preferable to set the value within the range.

In the electron transporting agent represented by the general formula (1), the electron mobility when the electric field strength is 5 × 10 ⁵ V / cm is 5 × 10 ^{−10 to} 5 × 10 ⁻⁷ cm ² / V / sec. It is preferable to set the value within the range.
This is because electrons generated from the charge generating agent by exposure can be more efficiently transported to the substrate side or the photosensitive layer surface side.
That is, when the electron mobility is less than 5 × 10 ⁻¹⁰ cm ² / V / sec, the electrons generated in the charge generating agent can be efficiently transferred to the substrate side or when the image is continuously formed. This is because it may be difficult to transport to the photosensitive layer surface side. On the other hand, if the electron mobility exceeds 5 × 10 ⁻⁷ cm ² / V / sec, electrons may easily be injected from the substrate side to the photosensitive layer.
Therefore, it is more preferable to set the electron mobility within a range of 8 × 10 ⁻¹⁰ to 1 × 10 ⁻⁷ cm ² / V / sec, and 1 × 10 ^{−9 to} 5 × 10 ⁻⁸ cm ² / More preferably, the value is within the range of V / sec.
As a method for measuring the electron mobility, the concentration of the electron transport material is 40% by weight in a polycarbonate resin having an average molecular weight of 50,000 in order to reduce variation in the measurement of electron mobility. The added solution is used as a measurement sample coating solution. Next, the obtained coating solution is applied onto a substrate and heat-treated at 80 ° C. for 30 minutes to prepare a measurement sample having a thickness of 7 μm. The measurement sample thus obtained is measured for electron mobility at room temperature using a normal TOF (Time of Flight) method. The electric field strength at the time of measurement is set to a constant value of 5 × 10 ⁵ V / cm.

Moreover, it is preferable to make content of the electron transport agent represented by General formula (1) into the value within the range of 0.5-60 weight part with respect to 100 weight part of binder resin in a photosensitive layer.
The reason for this is that by setting the content of the electron transporting agent represented by the general formula (1) to a value within this range, electrons generated from the charge generating agent by exposure can be more efficiently converted to the substrate side or the photosensitive layer. This is because it can be transported to the surface side.
That is, when the content is less than 0.5 parts by weight with respect to 100 parts by weight of the binder resin in the photosensitive layer, the electrons generated in the charge generating agent are sufficiently transported to the substrate side or the photosensitive layer surface side. This is because it may be difficult. On the other hand, when the content exceeds 60 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer, the electron transfer agent is easily crystallized in the photosensitive layer or forms a uniform photosensitive layer. This may be difficult.
Therefore, the content of the electron transport agent having a specific structure is more preferably set to a value in the range of 1 to 50 parts by weight with respect to 100 parts by weight of the binder resin in the photosensitive layer, More preferably, the value is within the range.

Here, the relationship between the content of the electron transport agent having a specific structure in the photosensitive layer and the sensitivity in the single-layer electrophotographic photosensitive member provided with the photosensitive layer will be described with reference to FIG.
In FIG. 2, the content (parts by weight) of the electron transfer agent having a specific structure with respect to 100 parts by weight of the binder resin of the photosensitive layer is taken on the horizontal axis, and the sensitivity (V) in the electrophotographic photoreceptor is taken on the vertical axis. The characteristic curve is shown.
In addition, although it is an example as an electron transport agent which has a specific structure, the electron transport agent (ETM-1) represented by Formula (10) is used.
As understood from the characteristic curve, as the content (parts by weight) of a specific electron transfer agent increases, the value of sensitivity (V) changes critically, and a downwardly convex curve is formed. I'm drawing.
More specifically, when the content (parts by weight) of a specific electron transport agent is increased to 0.5 parts by weight, the sensitivity (V) value is rapidly increased from 155 to about 140V. It can be seen that the number has decreased. And when the value (parts by weight) of the specific electron transport agent is a value within the range of 0.5 to 60 parts by weight, the sensitivity (V) is stable at a low value of around 130V. You can see that it is maintained. On the other hand, in the range where the content (parts by weight) of the specific electron transport agent exceeds 60 parts by weight, the increase in the content causes an influence due to crystallization of the specific electron transport agent. It can be seen that the sensitivity value has increased.
Therefore, the sensitivity is suppressed to a low value of around 130 V by setting the content of the specific electron transfer agent to a value within the range of 0.5 to 60 parts by weight with respect to 100 parts by weight of the binder resin in the photosensitive layer. You can see that you can. Therefore, an electrophotographic photosensitive member having excellent sensitivity can be produced by setting the content of the specific electron transfer agent to a value within this range.
A method for measuring the sensitivity of the electrophotographic photosensitive member will be described in detail in Examples.

(4) -3 Hole transport agent The hole transport agent used in the present invention is not particularly limited. For example, a benzidine-based compound, a phenylenediamine-based compound, a naphthylenediamine-based compound, or a phenanthrene range. Amine compounds, oxadiazole compounds [eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole, etc.], styryl compounds [eg, 9- (4-diethylaminostyryl) anthracene ), Carbazole compounds [eg poly-N-vinylcarbazole, etc.], organic polysilane compounds, pyrazoline compounds [eg 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline etc.], hydrazone compounds, triphenylamine Compounds, indole compounds, oxazole compounds, Sazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, butadiene compounds, pyrene-hydrazone compounds, acrolein compounds, carbazole-hydrazone compounds, quinoline-hydrazone compounds, Stilbene compounds, stilbene-hydrazone compounds, diphenylenediamine compounds, and the like are preferably used. These may be used alone or in combination of two or more.

  In addition, specific examples of the hole transporting agent include compounds (HTM-1 to 4) represented by the following general formulas (12) to (15).

Moreover, it is preferable to make content of a hole transport agent into the value within the range of 1-120 weight part with respect to 100 weight part of binder resin.
The reason for this is that when the content of the hole transport agent is less than 1 part by weight, the hole transport ability of the photosensitive layer is extremely lowered, which may adversely affect image characteristics.
Further, when the added amount exceeds 120 parts by weight, there is a problem that dispersibility is lowered and crystallization is easily caused.
Accordingly, the content of the hole transport agent is preferably set to a value within the range of 5 to 100 parts by weight, and within a range of 10 to 90 parts by weight with respect to 100 parts by weight of the binder resin. Is more preferable.

(4) -4 Additive In constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer preferably contains a compound represented by the general formula (5) as an additive.
The reason for this is that even if a contaminating component adheres to the electrophotographic photosensitive member, the occurrence of cracks can be effectively prevented by the action of the compound represented by the general formula (5). is there.
That is, when contaminants adhere to the surface of the electrophotographic photosensitive member and the monomer component elutes to form vacancies in the photosensitive layer, the general formula (5) as an additive for the vacancies is formed. This is because the compound represented by the formula can act to release local stress and suppress the generation of cracks.
Therefore, even when a charge transport agent having a relatively high solubility is used, the generation of cracks in the photosensitive layer can be suppressed and stable image characteristics can be maintained over a long period of time.

Here, the mechanism of crack generation when contaminants adhere to the surface of the electrophotographic photosensitive member will be described in detail.
First, when a contaminant adheres to the surface of the electrophotographic photosensitive member, a monomer component in the photosensitive layer, in particular, a charge transport agent composed of a hole transport agent or an electron transport agent starts to elute.
Next, it is considered that a hole is formed in the binder resin of the photosensitive layer at the trace of the elution of the charge transfer agent, and a local stress is generated in the vicinity of the hole to generate a crack. In other words, the occurrence of cracks can be regarded as a combination of two phenomena: a phenomenon of monomer component elution and a phenomenon of stress generation near the vacancies.
In this way, when the crack generation mechanism is captured, crack resistance can be effectively obtained by taking a predetermined measure against the stress generation in the vicinity of the voids as the second stage.
That is, by adding a specific additive, the generated stress can be relaxed and the occurrence of cracks can be suppressed.
Furthermore, while limiting the kind of additive and also controlling the molecular weight and the added amount within a predetermined range, the stress in the vicinity of the vacancies can be relaxed more effectively.

  Moreover, as a suitable example of a compound represented by General formula (5), the compound (BP-1-20) represented by following formula (16) is mentioned.

Moreover, it is preferable to make content of the additive mentioned above into the value within the range of 2-14 weight% with respect to solid content (100 weight%) of a photosensitive layer.
The reason for this is that by making the content of the additive within such a range, the occurrence of cracks can be more effectively suppressed, and the amount of charge transport agent eluted from the photosensitive layer under predetermined conditions. This is because it becomes easy to adjust the value.
That is, when the content of the compound is less than 2% by weight, the stress relaxation action as described above cannot be sufficiently exhibited, and it is difficult to sufficiently prevent the occurrence of cracks. On the other hand, when the content of the compound exceeds 14% by weight, the glass transition point of the photosensitive layer is lowered, and the wear resistance may be lowered. Moreover, it is because the dispersibility in binder resin falls and the case where it crystallizes is seen.
Therefore, the content of the additive is more preferably set to a value within the range of 3 to 12% by weight, and further preferably set to a value within the range of 4 to 10% by weight.
The solid content of the photosensitive layer means the constituent components of the photosensitive layer excluding the solvent. In the present invention, the total of the charge generating agent, the charge transporting agent, the binder resin, and the additive. It means the amount added.

(4) -5 Binder Resin As the binder resin constituting the charge transport layer, various resins conventionally used for the photosensitive layer can be used.
For example, polycarbonate resin, polyester resin, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene , Ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide, polyurethane, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, Thermosetting resins such as polyether resins, silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, other cross-linkable thermosetting resins, epoxy acrylate, urethane acrylate, etc. Resin butter, and the like can be used.
These binder resins can be used alone or in combination of two or more. Among these, polycarbonate resins and the like are preferable binder resins because they are excellent in transparency and heat resistance, and are excellent in mechanical properties and compatibility with charge transport agents.

Further, as the above-mentioned polycarbonate resin, in particular, a polycarbonate resin represented by the general formula (2) is used, and a value obtained by dividing the inorganic degree in the polycarbonate resin by the organic degree (I / O value) is 0. A value of .37 or more is preferable.
This is because the dispersibility and stability of the charge transport agent can be improved by using such a polycarbonate resin as a binder resin. Further, this is because the stain resistance and wear resistance of the electrophotographic photosensitive member can be improved.
Therefore, it is possible not only to suppress the generation of cracks, but also to suppress the crystallization of the charge transport agent in the photosensitive layer, and to make charge transport more efficient, even when repeatedly used for a long period of time or by adhesion of finger oil. .
However, when the I / O value in such a polycarbonate resin becomes excessively large, the miscibility with the charge transfer agent may decrease.
Therefore, the I / O value of the polycarbonate resin is more preferably set to a value within the range of 0.375 to 1.7, and more preferably set to a value within the range of 0.38 to 1.6.

Here, the concept of the I / O value will be described in detail. For example, KUMAMOTO PHARMACEUTICAL BULLETIN, No. 1, No. 1-16 (1954); Chemistry, Vol. 11, No. 10, No. 719- 725 (1957); Fragrance Journal, 34, 97-111 (1979); Fragrance Journal, 50, 79-82 (1981); Yes.
That is, one carbon (C) is organic 20, and based on that, the inorganic value and organic value of each polar group are determined as shown in Table 1, and the sum of nonpolar values in each polar group (I value) Then, the sum of organic values (O value) is obtained and the respective ratios are taken as I / O values.
In Table 1, R mainly represents an alkyl group, and φ mainly represents an alkyl group or an aryl group. As can be easily understood from this table, the closer the I / O value is to 0, the more non-polar (hydrophobic and organic) organic compounds are shown, and the higher the I / O value, the more polar (hydrophilic) It can be said that it is an organic compound having a large property and inorganic property.

In addition, such I / O values divide the properties of compounds into organic groups that exhibit covalent bonding and inorganic groups that exhibit ionic bonding, and all organic compounds are named as organic and inorganic axes. It can be said that the index is located at each point on the orthogonal coordinates. That is, the inorganic value is obtained by quantifying the magnitude of the influence of various substituents and bonds of an organic compound on the boiling point based on the hydroxyl group.
Specifically, when the distance between the boiling point curve of the linear alcohol and the boiling point curve of the linear paraffin is about 100 ° C., the influence of one hydroxyl group is set to 100 as a numerical value. Based on this numerical value, the value obtained by quantifying the influence of various substituents or various bonds on the boiling point is the inorganic value of the substituent that the organic compound has. For example, as shown in Table 1, the inorganic value of the —COOH group is 150, and the inorganic value of the double bond is 2. Therefore, the inorganic value of a certain organic compound means the sum of inorganic values such as various substituents and bonds of the organic compound.

Further, as the other polycarbonate resin, it is also preferable to use a polycarbonate resin represented by the general formulas (3) and (4) or a polycarbonate resin represented by any one of them.
This is because the dispersibility and stability of the charge transfer agent can be further improved. Further, this is because the contamination resistance and wear resistance of the electrophotographic photosensitive member can be further improved.
That is, a polycarbonate resin having such a structure can adjust the balance among the electrical characteristics, abrasion resistance, stain resistance, etc. of the electrophotographic photosensitive member to a suitable state.
In addition, it is preferable that the I / O value in the polycarbonate resin represented by the general formulas (3) to (4) is less than 0.37.
This reason is represented by the general formula (1) in which the value of the I / O value is 0.37 or more by setting the value of the I / O value in the polycarbonate resin to a value less than 0.37. This is because the characteristics of the binder resin when used together with the polycarbonate resin can be easily adjusted.

  Specific examples of the polycarbonate resin represented by the general formula (2) described above include polycarbonate resins (Resin-1 and 2) represented by the following formulas (17) to (18).

  Specific examples of the polycarbonate resin represented by the general formulas (3) to (4) described above include polycarbonate resins (Resin-3 to 4) represented by the following formulas (19) to (20), respectively. It is done.

(5) Manufacturing method Although it does not restrict | limit especially as a manufacturing method of a single layer type electrophotographic photoreceptor, it can implement in the following procedures.
First, a coating solution is prepared by adding a charge generating agent, a charge transporting agent, a binder resin, an additive and the like to a solvent. The coating solution thus obtained is applied onto a substrate (aluminum tube) using a coating method such as a dip coating method, a spray coating method, a bead coating method, a blade coating method, or a roller coating method. .
Then, for example, it is dried with hot air at 100 ° C. for 30 minutes to obtain a single layer type electrophotographic photosensitive member having a photosensitive layer having a predetermined thickness.
In addition, as a solvent for making a dispersion liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; Aromatic hydrocarbons such as benzene, toluene, xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane Ethers such as 1,4-dioxane, ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformaldehyde, dimethyl Examples include tilformamide and dimethyl sulfoxide. These solvents are used alone or in admixture of two or more. At this time, in order to improve the dispersibility of the charge generating agent and the smoothness of the surface of the photoreceptor layer, a surfactant, a leveling agent and the like may be added.

It is also preferable to form an intermediate layer on the substrate before forming this photosensitive layer.
In forming this intermediate layer, a binder resin and, if necessary, an additive (organic fine powder or inorganic fine powder) together with an appropriate dispersion medium, a known method such as a roll mill, ball mill, attritor, paint shaker, ultrasonic wave A coating solution is prepared by dispersing and mixing using a disperser or the like, and this is applied by a known means such as a blade method, a dipping method, or a spray method, and subjected to heat treatment to form an intermediate layer.
In addition, the additive is in a range where precipitation during production does not become a problem, and various additives (organic fine powder or inorganic fine powder are used for the purpose of preventing the occurrence of interference fringes by causing light scattering. ) Can be added in small amounts.
Next, the obtained coating solution is applied to a support substrate (aluminum base tube) according to a known production method, such as dip coating, spray coating, bead coating, blade coating, roller coating, etc. It can apply | coat using the apply | coating method.
Then, it is preferable to perform the process of drying the coating liquid on a base | substrate at the temperature of 20-200 degreeC for 5 minutes-2 hours.

  In addition, as a solvent for making such a coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol, and butanol; aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane. Aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and chlorobenzene; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide and the like. These solvents are used alone or in admixture of two or more.

2. Laminated Electrophotographic Photoreceptor (1) Basic Structure It is also preferable to use a laminated electrophotographic photoreceptor as shown in FIG. 3A as the electrophotographic photoreceptor of the present invention.
The reason for this is that the electrophotographic photoreceptor of the present invention can maintain excellent sensitivity even when it is repeatedly used by the action of an electron transport agent having a specific structure, and can be used as an exposure memory. It is because it can suppress effectively. In particular, when the photosensitive layer is a laminated type, it effectively suppresses the generation of residual charges, which are known to occur easily at the interface between the stacked layers or between the layer and the substrate. It is because it can do.
That is, by containing an electron transport agent having a specific structure in either the charge generation layer and / or the charge transport layer, electrons generated from the charge generation agent by exposure can be efficiently transferred to the substrate side, or This is because it can be transported to the surface side of the photosensitive layer.

Here, the basic structure of the multilayer electrophotographic photosensitive member will be described.
That is, as shown in FIG. 3, in the multilayer electrophotographic photosensitive member, a charge generation layer 24 containing a charge generation agent is formed on the substrate 12 by means of vapor deposition or coating, and then the charge generation layer 24 is formed. The charge transporting layer 22 can be formed by applying a coating liquid containing a charge transporting agent and a binder resin and drying it.
In contrast to the above-described structure, as shown in FIG. 3B, the charge transport layer 22 may be formed on the substrate 12, and the charge generation layer 24 may be formed thereon. However, since the charge generation layer 24 is much thinner than the charge transport layer 22, for protection, the charge transport layer 22 is formed on the charge generation layer 24 as shown in FIG. It is more preferable to form
It is also preferable to form the intermediate layer 25 on the substrate as in the case of the single layer type electrophotographic photosensitive member.

The charge generation layer forming coating solution and the charge transport layer forming coating solution are, for example, a predetermined component such as a charge generating agent, a charge transporting agent, a binder resin, a dispersion medium, a roll mill, a ball mill, an attritor, a paint. It can be prepared by dispersing and mixing using a shaker, an ultrasonic disperser or the like.
In the laminated photosensitive layer 20, the thickness of the photosensitive layer (charge generation layer and charge transport layer) is not particularly limited, but the charge generation layer is preferably 0.01 to 5 μm, more preferably 0.1 to 0.1 μm. The thickness is 3 μm, and the charge transport layer is preferably 2 to 100 μm, more preferably 5 to 50 μm.
The content of the charge generation agent in the charge generation layer is preferably set to a value within the range of 5 to 1000 parts by weight with respect to 100 parts by weight of the binder resin of the charge generation layer, and within the range of 30 to 500 parts by weight. It is more preferable to set the value within the range.

(2) Electron transport agent In the multilayer electrophotographic photosensitive member of the present invention, the electron transport agent represented by the general formula (1) may be contained in either the charge generation layer or the charge transport layer. , It may be contained in both the charge generation layer and the charge transport layer.
Hereinafter, the case where the charge generation layer is contained (first inclusion form) and the case where the charge generation layer is contained (second inclusion form) will be described separately.

(2) -1 First Inclusion Form The content of the electron transfer agent represented by the general formula (1) in the charge generation layer contained in the multilayer photosensitive layer is set to 100 parts by weight of the binder resin in the charge generation layer. The value is preferably within the range of 1 to 90 parts by weight.
The reason for this is that by adding an electron transport agent having such a specific structure to the charge generation layer, it is likely to occur particularly at the interface between the stacked layers or the interface between the layer and the substrate. This is because generation of known residual charges can be effectively suppressed.
That is, for example, in the case of a negatively charged type laminated electrophotographic photosensitive member, an electron transport agent having such a specific structure is contained in the charge generation layer, whereby the electrons generated in the charge generation layer are efficiently converted. This is because it can escape to the substrate side and the generation of residual charges can be suppressed.
The reason why the content of the electron transfer agent having a specific structure is set to a value within the above-described range is that the addition amount is less than 1 part by weight with respect to 100 parts by weight of the binder resin in the charge generation layer. This is because it may be difficult to sufficiently suppress the generation of the residual charge described above. On the other hand, when the content of the electron transport agent having a specific structure is set to a value exceeding 90 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer, the electron transport agent is easily crystallized in the charge generation layer. This is because it may cause a decrease in the dispersibility of the charge generating agent.
Therefore, the content of the electron transfer agent having a specific structure is more preferably 4 to 80 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer, more preferably 10 to 60 parts by weight. It is more preferable to set the value within the range.

Here, the relationship between the content of the electron transport agent having a specific structure in the charge generation layer and the exposure memory in the multilayer electrophotographic photoreceptor provided with the charge generation layer will be described with reference to FIG.
In FIG. 4, the content (parts by weight) of the electron transfer agent having a specific structure with respect to 100 parts by weight of the binder resin of the charge generation layer is taken on the horizontal axis, and the exposure memory (V) in the electrophotographic photosensitive member is taken on the vertical axis. The characteristic curve which took (after 2,000 durable printing) is shown.
In addition, although it is an example as an electron transport agent which has a specific structure, the electron transport agent (ETM-1) represented by Formula (10) is used.
As understood from the characteristic curve, it can be seen that the value of the exposure memory (V) changes critically as the content (parts by weight) of the specific electron transport agent increases.
More specifically, when the value of the content (parts by weight) of a specific electron transport agent is increased to 1 part by weight, the value of the exposure memory (V) suddenly increases from 30 to about 25V. It turns out that it is decreasing. When the content (parts by weight) of the specific electron transfer agent is a value within the range of 1 to 90 parts by weight, the exposure memory (V) stably maintains a low value around 20V. You can see that On the other hand, when the content (parts by weight) of the specific electron transport agent exceeds 90 parts by weight, the crystallization of the specific electron transport agent or the dispersion of the charge generation agent is accompanied with the increase of the content. It can be seen that the value of the exposure memory is gradually increasing because of the influence of the decrease in performance.
Therefore, the exposure memory is suppressed to a low value of around 20 V by setting the content of the specific electron transfer agent to a value in the range of 1 to 90 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer. You can see that you can. Therefore, by setting the content of the specific electron transporting agent to a value within this range, it is possible to form a high-quality image while suppressing the generation of a memory image.
In addition, the measuring method of the exposure memory in an electrophotographic photosensitive member is explained in full detail in an Example.

Here, the relationship between the content of the electron transport agent having a specific structure in the charge generation layer and the sensitivity in the multilayer electrophotographic photosensitive member provided with the charge generation layer will be described with reference to FIG. .
In FIG. 5, the content (parts by weight) of the electron transporting agent having a specific structure with respect to 100 parts by weight of the binder resin of the charge generation layer is taken on the horizontal axis, and the sensitivity (V) in the electrophotographic photosensitive member is taken on the vertical axis. A characteristic curve obtained after 2,000 durable printing) is shown.
In addition, although it is an example as an electron transport agent which has a specific structure, the electron transport agent (ETM-1) represented by Formula (10) is used.
As understood from the characteristic curve, the value of sensitivity (V) gradually increases as the content (parts by weight) of a specific electron transport agent increases.
More specifically, when the content (parts by weight) of a specific electron transport agent is increased to 90 parts by weight, the sensitivity (V) value gradually increases from 34 to about 45V. You can see that Then, it can be seen that when the content (parts by weight) of the specific electron transport agent exceeds 90 parts by weight, the sensitivity (V) increases as it is and becomes a high value exceeding 50V.
Therefore, the sensitivity is suppressed to a low value of around 40 V by setting the content of the specific electron transfer agent to a value within the range of 1 to 90 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer. You can see that Therefore, an electrophotographic photosensitive member having excellent sensitivity can be produced by setting the content of the specific electron transfer agent to a value within this range. Here, the reason why the lower limit of the content of the specific electron transfer agent is 1 part by weight with respect to 100 parts by weight of the binder resin in the charge generation layer is that, as described above, the content is less than 1 part by weight. When the value is reached, it is difficult to sufficiently suppress the generation of residual charges, and it may be difficult to effectively suppress the exposure memory.
A method for measuring the sensitivity of the electrophotographic photosensitive member will be described in detail in Examples.

(2) -2 Second Form of Containment The content of the electron transport agent represented by the general formula (1) in the charge transport layer contained in the multilayer photosensitive layer is based on 100 parts by weight of the binder resin in the charge transport layer. The value is preferably in the range of 0.05 to 80 parts by weight.
The reason for this is that by containing an electron transport agent having such a specific structure in the charge transport layer, electrons generated from the charge generator in the charge generation layer can be quickly transported to the surface of the electrophotographic photoreceptor. This is because the generation of residual charges can be effectively suppressed and an electrostatic latent image can be formed efficiently.
That is, in the case of a negatively charged multilayer electrophotographic photosensitive member, the charge transport layer contains an electron transport agent having such a specific structure together with a hole transport agent in the charge transport layer. This is because, as a result of improving the hole transport capability, the generation of residual charges can be suppressed, the sensitivity is improved, and an electrostatic latent image can be efficiently formed.
Further, in the case of a positively charged type laminated electrophotographic photoreceptor, the electron transporting ability in the charge transporting layer can be obtained by adding an electron transporting agent having such a specific structure as the electron transporting agent in the charge transporting layer. As a result, the generation of residual charges can be suppressed, and electrons generated in the charge generation layer can be quickly transported to the surface of the photoreceptor to efficiently form an electrostatic latent image.
The reason why the content of the electron transfer agent having a specific structure is a value within the above-described range is that the addition amount is less than 0.05 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer. This is because efficient charge transport in the charge transport layer may be difficult. On the other hand, when the content of the electron transport agent having a specific structure is set to a value exceeding 80 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer, the electron transport agent is easily crystallized in the charge transport layer. This is because it may be difficult to form a uniform charge transport layer.
Therefore, the content of the electron transport agent having a specific structure is more preferably set to a value within the range of 0.1 to 70 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer. More preferably, the value is within the range of parts by weight.
In particular, in the case where an electron transport agent having a specific structure is contained together with a hole transport agent in the charge transport layer of the negatively charged multilayer electrophotographic photosensitive member, the electron transport agent having a specific structure is included. Is preferably set to a value within a range of 0.05 to 30 parts by weight, and a value within a range of 1 to 20 parts by weight with respect to 100 parts by weight of the binder resin of the charge transport layer. More preferred.

Here, the relationship between the content of the electron transport agent having a specific structure in the charge transport layer and the exposure memory in the multilayer electrophotographic photoreceptor provided with the charge generation layer will be described with reference to FIG.
In FIG. 6, the content (parts by weight) of the electron transport agent having a specific structure with respect to 100 parts by weight of the binder resin of the charge transport layer is taken on the horizontal axis, and the exposure memory (V) on the electrophotographic photosensitive member is taken on the vertical axis. The characteristic curve which took (after 2,000 durable printing) is shown.
In addition, such a multilayer electrophotographic photosensitive member is a negatively charged type, and as an example of an electron transport agent having a specific structure, an electron transport agent (ETM-1) represented by the formula (10) is used. Furthermore, 70 parts by weight of the hole transporting agent (HTM-1) represented by the formula (12) is included.
As understood from the characteristic curve, as the content (parts by weight) of a specific electron transfer agent increases, the value of the exposure memory (V) changes critically, and the downward convex curve Is drawn.
More specifically, when the value (parts by weight) of the specific electron transport agent is increased to 0.05 parts by weight, the value of the exposure memory (V) is increased from 30 to about 25 V accordingly. It turns out that it decreases rapidly. When the content (parts by weight) of the specific electron transfer agent is a value within the range of 0.05 to 30 parts by weight, the exposure memory (V) stabilizes a low value around 25V. It can be seen that On the other hand, in the range in which the content (parts by weight) of the specific electron transport agent exceeds 30 parts by weight, the increase in the content causes an influence due to crystallization of the specific electron transport agent. It can be seen that the value of the exposure memory gradually increases.
Therefore, by setting the content of the specific electron transfer agent to a value within the range of 0.5 to 30 parts by weight with respect to 100 parts by weight of the binder resin in the photosensitive layer, the exposure memory is reduced to a low value of around 25V. It turns out that it can suppress. Therefore, by setting the content of the specific electron transporting agent to a value within this range, it is possible to form a high-quality image while suppressing the generation of a memory image.
In addition, the measuring method of the exposure memory in an electrophotographic photosensitive member is explained in full detail in an Example.

Here, the relationship between the content of the electron transport agent having a specific structure in the charge transport layer and the sensitivity of the multilayer electrophotographic photoreceptor provided with the charge generation layer will be described with reference to FIG. .
In FIG. 7, the content (parts by weight) of the electron transport agent having a specific structure with respect to 100 parts by weight of the binder resin of the charge transport layer is taken on the horizontal axis, and the sensitivity (V) in the electrophotographic photoreceptor is taken on the vertical axis. A characteristic curve obtained after 2,000 durable printing) is shown.
In addition, such a multilayer electrophotographic photosensitive member is a negatively charged type, and as an example of an electron transport agent having a specific structure, an electron transport agent (ETM-1) represented by the formula (10) is used. Furthermore, 70 parts by weight of the hole transporting agent (HTM-1) represented by the formula (12) is included.
As understood from the characteristic curve, as the content (parts by weight) of a specific electron transfer agent increases, the value of sensitivity (V) changes critically, and a downwardly convex curve is formed. I'm drawing.
More specifically, when the content (parts by weight) of a specific electron transport agent is increased to 0.05 parts by weight, the sensitivity (V) value increases rapidly from 35 to about 30 V. It can be seen that the number has decreased. And when the value (parts by weight) of the specific electron transport agent is a value within the range of 0.05 to 30 parts by weight, the sensitivity (V) is stable at a low value around 25V. You can see that it is maintained. On the other hand, in the range where the content (parts by weight) of the specific electron transport agent exceeds 30 parts by weight, the crystallization of the specific electron transport agent or the dispersion of the charge generation agent is accompanied with the increase of the content. It can be seen that the sensitivity value is increased because of an influence such as a decrease in property.
Therefore, the sensitivity is suppressed to a low value of around 25 V by setting the content of the specific electron transfer agent to a value within the range of 0.05 to 30 parts by weight with respect to 100 parts by weight of the binder resin in the photosensitive layer. You can see that you can. Therefore, an electrophotographic photosensitive member having excellent sensitivity can be produced by setting the content of the specific electron transfer agent to a value within this range.
A method for measuring the sensitivity of the electrophotographic photosensitive member will be described in detail in Examples.

[Second Embodiment]
The second embodiment includes the electrophotographic photosensitive member of the first embodiment, and a charging unit, an exposure unit, a developing unit, and a transfer unit are arranged around the electrophotographic photosensitive member. The image forming apparatus.
Hereinafter, the contents already described in the first embodiment will be omitted, and the second embodiment will be described focusing on differences from the first embodiment.
A case where a single layer type electrophotographic photosensitive member is used as the electrophotographic photosensitive member will be described as an example.

As shown in FIG. 8, around the electrophotographic photosensitive member 31, a charger 32, an exposure light source 33, a developing unit 34, a transfer unit 35, and a cleaning unit 37 are sequentially arranged.
The electrophotographic photosensitive member 31 rotates at a constant speed in the direction of the arrow, and the electrophotographic process is performed on the surface of the electrophotographic photosensitive member 31 in the following order. More specifically, the electrophotographic photosensitive member 31 is entirely charged by the charger 32, and then the print pattern is exposed by the exposure light source 33.
Next, the developing device 34 develops toner corresponding to the print pattern, and the transfer device 35 further transfers the toner to a transfer material (paper) 36.
Here, the developer 34a in which the toner is dispersed is conveyed by the developing roller 34b, and the toner is attracted onto the surface of the electrophotographic photosensitive member 31 by applying a predetermined developing bias. It will be developed on top.
Next, the transfer material (paper) 36 onto which the toner image has been transferred is separated from the surface of the electrophotographic photosensitive member 31 by a separating means (not shown) and conveyed to a fixing device by a conveying belt. Next, the toner image is fixed on the surface by being heated and pressurized by the fixing device, and then discharged to the outside of the image forming apparatus by a discharge roller.
On the other hand, the electrophotographic photosensitive member 31 after the transfer of the toner image continues to rotate, and residual toner (adhered matter) that has not been transferred to the transfer material 36 at the time of transfer is removed from the surface of the electrophotographic photosensitive member 31 by the cleaning unit 37. The Further, the charge remaining on the surface of the electrophotographic photosensitive member 31 is completely erased by the discharge of the discharge light from the discharger 38 and is used for the next image formation.
That is, the electrophotographic photoreceptor mounted on the image forming apparatus of the present invention can maintain excellent sensitivity even when repeatedly used, and can effectively suppress the exposure memory. Therefore, the image forming apparatus of the present invention can stably produce a high-quality image even when it is repeatedly used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these description content.

[Example 1]
1. Manufacture of a single layer type electrophotographic photoreceptor As a charge generating agent, 3.5 parts by weight of an X-type metal-free phthalocyanine (CGM-1) represented by the formula (6) and a hole transporting agent, the formula (12) 50 parts by weight of the compound represented by formula (HTM-1) and 30 parts by weight of the compound represented by formula (10) (ETM-1) as an electron transporting agent, and represented by the following formula (21) 10 parts by weight of a diphenoquinone compound (ETM-3) and 60 parts by weight of a Z-type polycarbonate resin (Resin-3) represented by formula (19) (viscosity average molecular weight: 20,000) as a binder resin, 35 parts by weight of a polycarbonate resin (Resin-1) represented by the formula (17) (viscosity average molecular weight: 50,000) and 5 parts by weight of a polyester resin (Toyobo Co., Ltd., Byron RV200) are used as additives. In the formula (16) 10 parts by weight of metaterphenyl (BP-3) represented in the above, and 0.1 parts by weight of dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-96-50CS) as a leveling agent And 620 parts by weight of tetrahydrofuran were mixed and dispersed with an ultrasonic disperser to prepare a photosensitive layer coating solution.
Next, the obtained coating solution is applied onto a cylindrical aluminum tube (diameter 30 mm, length 254 mm), and dried with hot air under conditions of 120 ° C. for 40 minutes, so that the film thickness is 30 μm. An electrophotographic photoreceptor was obtained.

2. Evaluation of single layer type electrophotographic photosensitive member (1) Evaluation of sensitivity The sensitivity of the obtained single layer type electrophotographic photosensitive member was evaluated.
That is, the developing means was removed from the imaging unit in the printer (FS1010, manufactured by Kyocera Mita Co., Ltd.) employing the positively charged reversal development process, and a potential measuring device was attached thereto to create an imaging unit for measuring potential. . Such a potential measuring device has a configuration in which a potential measuring probe is arranged with respect to the developing position of the imaging unit. Further, such a potential measuring probe was disposed with respect to the center in the axial direction of the electrophotographic photosensitive member, and the distance between the potential measuring probe and the surface of the electrophotographic photosensitive member was 5 mm.
Next, the obtained single-layer type electrophotographic photosensitive member is mounted on the above-described potential measurement imaging unit, and positively charged in a normal temperature and humidity environment (temperature: 23 ° C., humidity: 50% RH). Exposure corresponding to a black image was performed, and the potential of the exposed portion was measured to obtain sensitivity V ₁ (V).
Similarly, the sensitivity V ₂ (V) after 2,000 A4 size durable printing was measured on a 1% original, and the difference from the sensitivity V ₁ (V) before durable printing (V ₁ −V _2). ) (V) was obtained and defined as the sensitivity change (V). The obtained results are shown in Table 2.

(2) Evaluation of fog image Further, the fog image was evaluated using the obtained single layer type electrophotographic photosensitive member.
That is, the obtained single-layer type electrophotographic photosensitive member was mounted on a printer (FS1010, manufactured by Kyocera Mita Corporation), and a blank paper image was formed in a high temperature and high humidity environment (temperature 35 ° C., relative humidity 85%). Subsequently, the density FD ₁ value (−) of the obtained blank paper image was subtracted from the density FD ₀ value (−) of the non-output white paper, and the FD value (−) was calculated to evaluate the fogged image. The obtained results are shown in Table 2.

(3) Evaluation of oil and fat resistance Moreover, oil and fat resistance was evaluated using the obtained single layer type electrophotographic photosensitive member.
That is, the surface of the obtained single-layer type electrophotographic photosensitive member was touched by hand, and an oil and fat component was adhered thereto, and left for 24 hours at room temperature and normal humidity (temperature 23 degrees, relative humidity 50% RH).
Next, the surface of the single-layer electrophotographic photoreceptor after standing was observed with an optical microscope, the number of cracks per 1 cm × 1 cm square was measured, and evaluated according to the following criteria.
A: No crack is generated. B: The number of cracks is 0 to 5 or less. Δ: The number of cracks is 6 to 20 or less. X: The number of cracks is 21 or more.

[Example 2]
In Example 2, the azoquinone compound used in combination with the diphenoquinone compound (ETM-3) represented by the formula (21) was changed to a compound (ETM-2) represented by the formula (11). A single layer type electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1. The obtained results are shown in Table 2.

[Examples 3 to 5]
In Examples 3 to 5, a single layer was formed in the same manner as in Example 1 except that the hole transporting agents were compounds (HTM-2 to 4) represented by formulas (13) to (15), respectively. Type electrophotographic photoreceptors were manufactured and evaluated. The obtained results are shown in Table 2.

[Examples 6 to 8]
Further, in Examples 6 to 8, a single layer type was used in the same manner as in Example 1 except that the charge generators were compounds (CGM-2 to 4) represented by formulas (7) to (9), respectively. An electrophotographic photoreceptor was manufactured and evaluated. The obtained results are shown in Table 2.
In Example 6, in addition to the compound (CGM-2) represented by the formula (7), 3 parts by weight of Pigment Yellow 110 was added to 100 parts by weight of the binder resin.

Moreover, the crystal | crystallization of the titanyl phthalocyanine (CGM-2) represented by Formula (7) as a charge generator used in Example 6 was created in the following procedures.
First, 25 g of o-phthalonitrile, 28 g of titanium tetrabutoxide, 20 g of urea, and 300 g of quinoline were added to a flask purged with argon, and the temperature was raised to 150 ° C. while stirring. Next, after evaporating the steam generated from the reaction system, the temperature was raised to 215 ° C. while the reaction temperature was maintained, and the reaction was further continued for 2 hours while maintaining the reaction temperature.
After completion of the reaction, when the reaction mixture is cooled to 150 ° C., the reaction mixture is taken out from the flask, filtered through a glass filter, and the resulting solid is washed successively with N, N-dimethylformamide and methanol and then vacuum-dried. 25 g of a purple solid was obtained. (Pigmentation pretreatment)

  Next, 15 g of the obtained blue-violet solid was added to 100 ml of N, N-dimethylformamide, heated to 130 ° C. with stirring, and stirred for 2 hours. Next, heating was stopped at the time when 2 hours had elapsed, and after cooling to 23 ± 1 ° C., stirring was stopped, and the liquid was allowed to stand in this state for 12 hours for stabilization treatment. Subsequently, the stabilized liquid was filtered off with a glass filter, and the obtained solid was washed with methanol and then vacuum-dried to obtain 9.83 g of a crude crystal of a titanyl phthalocyanine compound. (Pre-acid treatment process)

Next, 5 g of the crude crystal of titanyl phthalocyanine obtained in the above-mentioned pre-acid treatment step was added to 100 ml of concentrated sulfuric acid and dissolved. Next, this solution was added dropwise to ice-cooled water, stirred for 15 minutes at room temperature, and then allowed to stand at about 23 ± 1 ° C. for 30 minutes for recrystallization. Next, the liquid described above was filtered off with a glass filter, and the obtained solid was washed with water until the washing liquid became neutral, and then dispersed in 200 ml of chlorobenzene in the presence of water without drying. The mixture was heated to 0 ° C. and stirred for 10 hours. Next, after the liquid was filtered off with a glass filter, the obtained solid was vacuum-dried at 50 ° C. for 5 hours to obtain crystals of unsubstituted titanyl phthalocyanine (CGM-2) represented by the formula (7) (blue color). 4.5 g of powder) was obtained. (Acid treatment process)
The obtained titanyl phthalocyanine was immersed in the initial and 1,3-dioxolane or tetrahydrofuran for 7 days, and the Bragg angle 2θ ± 0.2 ° = 7.4 ° and 26 ° in the CuKα characteristic X-ray diffraction spectrum was obtained. In addition to the fact that no peak occurs at 2 ° and the temperature rise process up to 400 ° C. in the differential scanning calorimetry, one peak at 302 ° C. is observed in addition to the peak around 90 ° C. accompanying vaporization of adsorbed water. confirmed.

In addition, the CuKα characteristic X-ray diffraction spectrum in the titanyl phthalocyanine crystal was measured by the following measuring method.
First, 0.3 g of titanyl phthalocyanine crystal was dispersed in 5 g of tetrahydrofuran and stored in a closed system for 24 hours under conditions of a temperature of 23 ± 1 ° C. and a relative humidity of 50-60% RH. A sample holder of RINT1100 (manufactured by Co., Ltd.) was filled for measurement.
Measurement conditions were as follows.
X-ray tube: Cu
Tube voltage: 40 kV
Tube current: 30 mA
Start angle: 3.0 °
Stop angle: 40.0 °
Scanning speed: 10 ° / min

Moreover, DSC (differential scanning calorimetry) of the titanyl phthalocyanine crystal was performed using a differential scanning calorimeter (TAS-200 type, DSC8230D manufactured by Rigaku Corporation). The measurement conditions are as follows.
Sample pan: Aluminum heating rate: 20 ° C / min

[Examples 9 to 13]
In Examples 9 to 13, the content of the azoquinone compound (ETM-1) represented by the formula (10) used in combination with the diphenoquinone compound (ETM-3) represented by the formula (21) is used. A single-layer electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that each was changed as shown in Table 2. The obtained results are shown in Table 2.

[Comparative Example 1]
In Comparative Example 1, a single-layer electrophotographic photosensitive member was produced in the same manner as in Example 1 except that only the diphenoquinone compound (ETM-3) represented by the formula (21) was used as the electron transport agent. And evaluated. The obtained results are shown in Table 2.

[Comparative Example 2]
In Comparative Example 2, the azoquinone compound used in combination with the diphenoquinone compound (ETM-3) represented by the formula (21) was changed to a compound (ETM-4) represented by the following formula (22), A single-layer electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1. The obtained results are shown in Table 2.

[Example 14]
1. Production of multilayer electrophotographic photoreceptor (1) Preparation of intermediate layer Titanium oxide surface-treated with alumina and silica in a container and then surface-treated with methylhydrogenpolysiloxane (Taika, MT-02, number average) After adding 250 parts by weight of primary particle size: 10 nm, 100 parts by weight of Amilan CM8000 (manufactured by Toray Industries, Inc., quaternary copolymer polyamide resin), 1000 parts by weight of methanol, and 250 parts by weight of butanol, The mixture was mixed for 1 hour using a bead mill (media: zirconia balls having a diameter of 0.5 mm) to obtain an intermediate layer coating solution.
Next, the obtained intermediate layer coating solution is filtered through a 5 micron filter, and then the intermediate layer coating is obtained with one end of an aluminum substrate (supporting substrate) having a diameter of 30 mm and a length of 238.5 mm facing upward. It was immersed in the liquid at a speed of 5 mm / sec and applied. Thereafter, heat treatment was performed at 130 ° C. for 30 minutes to form an intermediate layer having a thickness of 2 μm.

(2) Preparation of charge generation layer Next, 200 parts by weight of a titanyl phthalocyanine (CGM-2) crystal represented by the formula (7) produced in the same manner as in Example 6 and an azoquinone represented by the formula (10) 40 parts by weight of compound (ETM-1), 100 parts by weight of polyvinyl butyral resin (manufactured by Denki Kagaku Kogyo Co., Ltd., Denkabutyral 6000EP) as a binder resin, 4000 parts by weight of propylene glycol monomethyl ether as a dispersion medium, and 4000 of tetrahydrofuran Part by weight was mixed and dispersed for 48 hours using a bead mill to prepare a charge generation layer coating solution.
The resulting charge generation layer coating solution is filtered through a 3 micron filter, then applied to the intermediate layer by dip coating, and dried at 80 ° C. for 5 minutes to generate a charge having a thickness of 0.3 μm. A layer was formed.

(3) Preparation of charge transport layer Next, as a hole transport agent, 70 parts by weight of a hole transport agent (HTM-1) represented by the formula (12), and as an additive, BP- in the formula (16) 10 parts by weight of metaterphenyl represented by Formula 3, 70 parts by weight of a polycarbonate resin (Resin-3) represented by Formula (19) having a molecular weight of 20,500 as a binder resin, and Formula (17). 30 parts by weight of a polycarbonate resin (Resin-1) having a molecular weight of 50,000 and 600 parts by weight of tetrahydrofuran as a solvent were mixed and dissolved to prepare a coating solution for a charge transport layer.
The obtained charge transport layer coating solution was applied onto the charge generation layer in the same manner as the charge generation layer coating solution, dried at 120 ° C. for 30 minutes, and then a charge transport layer having a thickness of 20 μm was formed. The multilayer electrophotographic photosensitive member was formed.

2. Evaluation of Laminated Electrophotographic Photoreceptor (1) Evaluation of Sensitivity Further, the sensitivity of the obtained laminated electrophotographic photoreceptor was evaluated.
That is, the developing means is removed from the imaging unit in a printer (Oki Data Co., Ltd., MicroLine-22) that employs a negatively charged reversal development process, and a potential measuring device is attached to the imaging unit. Created. Such a potential measuring device has a configuration in which a potential measuring probe is arranged with respect to the developing position of the imaging unit. Further, such a potential measuring probe was disposed with respect to the center in the axial direction of the electrophotographic photosensitive member, and the distance between the potential measuring probe and the surface of the electrophotographic photosensitive member was 5 mm.
Next, the laminated electrophotographic photosensitive member after printing 2,000 sheets of A4 size paper with 1% original in a normal temperature and humidity environment (temperature: 23 ° C., humidity: 50% RH) is used for the above-described potential measurement. The imaging unit was negatively charged, exposure corresponding to a solid black image was performed, and the potential of the exposed portion was measured to obtain sensitivity (V). The obtained results are shown in Table 3. In addition, although the measured value of the obtained charging potential (V) and sensitivity (V) was a negative value, in Table 3, the absolute value (positive value) is described.

(2) Evaluation of exposure memory potential Moreover, the exposure memory potential in the obtained multilayer electrophotographic photosensitive member was evaluated.
That is, the above-described potential measurement is performed on the laminated electrophotographic photosensitive member after printing 2,000 sheets of A4 size paper with 1% original in a normal temperature and humidity environment (temperature: 23 ° C., relative humidity: 50% RH). Attached to the imaging unit for the first exposure (95 mm length) of the electrophotographic photosensitive member, exposure corresponding to a solid black image of 65 mm was performed (exposure portion), and the remaining 30 mm was not exposed (non-exposed) Exposure part). Next, the entire electrophotographic photoreceptor on the second round was not exposed. Next, the surface potential V ₀ b (V) in the second turn of the portion corresponding to the exposed portion of the first turn and the surface potential V ₀ (V) in the second turn of the portion corresponding to the non-exposed portion of the first turn. If the measured absolute value │V ₀ -V ₀ b│ the potential difference (V) was calculated, and the exposure memory potential (V). The obtained results are shown in Table 3.

(3) Evaluation of exposure memory image Moreover, the exposure memory image in the obtained multilayer electrophotographic photosensitive member was evaluated.
That is, the obtained multilayer electrophotographic photosensitive member is mounted on an imaging unit of a printer (Okidata MicroLine-22 manufactured by Oki Data Co., Ltd.) that employs a negatively charged reversal development process, and is in a normal temperature and normal humidity environment (temperature: After printing 2,000 sheets of A4 size paper with a 1% original at 23 ° C. and humidity: 50% RH, an arbitrary number of 10 mm square black square patterns were printed for one round of the electrophotographic photosensitive member. Next, an entire gray image and an entire blank paper image were printed and evaluated according to the following criteria. The obtained results are shown in Table 3.
A: The exposure memory image is not observed at all O: The exposure memory image is slightly observed, but the outline of the square is not observed Δ: The exposure memory image is slightly observed and the outline of the square is also observed x: The exposure memory The image is clearly observed

[Example 15]
In Example 15, a laminated electrophotographic photosensitive member was produced in the same manner as in Example 14 except that the azoquinone compound in the charge generation layer was changed to the compound (ETM-2) represented by the formula (11). ,evaluated. The obtained results are shown in Table 3.

[Examples 16 to 18]
Moreover, in Examples 16-18, it is the same as that of Example 14 except having used the hole transport agent in a charge transport layer as the compound (HTM-2-4) represented by Formula (13)-(15). A laminated electrophotographic photosensitive member was manufactured and evaluated. The obtained results are shown in Table 3.

[Example 19]
In Example 19, a multilayer electrophotographic photosensitive member was produced in the same manner as in Example 14 except that the charge generation agent in the charge generation layer was changed to the compound (CGM-3) represented by the formula (8). And evaluated. The obtained results are shown in Table 3.

[Examples 20 to 24]
Further, in Examples 20 to 24, except that the content of the azoquinone compound (ETM-1) represented by the formula (10) in the charge generation layer was changed as shown in Table 3, respectively, Example 14 and Similarly, a laminated electrophotographic photoreceptor was produced and evaluated. The obtained results are shown in Table 3.

[Comparative Example 3]
In Comparative Example 3, a laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 14 except that the charge generation layer did not contain an azoquinone compound. The obtained results are shown in Table 3.

[Comparative Examples 4 to 6]
Further, in Comparative Examples 4 to 6, the hole transport agent in the charge transport layer was the same as Comparative Example 3 except that the compounds (HTM-2 to 4) represented by the formulas (13) to (15) were used. A laminated electrophotographic photosensitive member was manufactured and evaluated. The obtained results are shown in Table 3.

[Example 25]
In Example 25, the azoquinone compound (ETM-1) represented by the formula (10) contained in the charge generation layer in the multilayer electrophotographic photosensitive member of Example 14 was not contained. On the other hand, in the charge transport layer, 5 parts by weight of the azoquinone compound (ETM-1) represented by the formula (10) was contained with respect to 100 parts by weight of the binder resin of the charge transport layer. Then, the laminated electrophotographic photosensitive member was manufactured and evaluated in the same manner as in Example 14 except for the points described above. Table 4 shows the obtained results.

[Example 26]
In Example 26, a laminated electrophotographic photosensitive member was produced in the same manner as in Example 25 except that the azoquinone compound in the charge transport layer was changed to the compound (ETM-2) represented by the formula (11). ,evaluated. Table 4 shows the obtained results.

[Examples 27 to 29]
In Examples 27 to 29, the hole transport agent in the charge transport layer was the same as that of Example 25 except that the compounds (HTM-2 to 4) represented by formulas (13) to (15) were used. A laminated electrophotographic photosensitive member was manufactured and evaluated. Table 4 shows the obtained results.

[Examples 30 to 34]
Further, in Examples 30 to 34, the content of the azoquinone compound (ETM-1) represented by the formula (10) in the charge transport layer was changed as shown in Table 4, respectively. Similarly, a laminated electrophotographic photoreceptor was produced and evaluated. The obtained results are shown in Table 3.

  According to the electrophotographic photosensitive member and the image forming apparatus of the present invention, the photosensitive layer of the electrophotographic photosensitive member includes an electron transport agent having a specific structure, so that excellent sensitivity can be obtained even when used repeatedly. Can be maintained, and the exposure memory can be effectively suppressed. Therefore, the electrophotographic photosensitive member and the image forming apparatus are expected to make a significant contribution to improving electrical characteristics and image characteristics in various image forming apparatuses such as copying machines and printers.

(A)-(b) is a figure provided in order to demonstrate the structure of the single layer type electrophotographic photoreceptor concerning this invention. It is a figure provided in order to demonstrate the relationship between content of the specific electron transfer agent in a single layer type photosensitive layer, and a sensitivity. (A)-(b) is a figure provided in order to demonstrate the structure of the laminated electrophotographic photoreceptor concerning this invention. It is a figure provided in order to demonstrate the relationship between content of the specific electron transport agent in the charge generation layer of a lamination type photosensitive layer, and exposure memory. It is a figure provided in order to demonstrate the relationship between content of the specific electron transport agent in the charge generation layer of a lamination type photosensitive layer, and a sensitivity. It is a figure provided in order to demonstrate the relationship between content of the specific electron transport agent in the charge transport layer of a lamination type photosensitive layer, and exposure memory. It is a figure provided in order to demonstrate the relationship between content of the specific electron transport agent in the charge transport layer of a lamination type photosensitive layer, and a sensitivity. 1 is a diagram for explaining an image forming apparatus according to the present invention.

Explanation of symbols

10: Single layer type electrophotographic photosensitive member, 12: Substrate, 14: Photosensitive layer, 16: Intermediate layer, 20: Laminated electrophotographic photosensitive member, 22: Charge transport layer, 24: Charge generation layer, 25: Intermediate layer, 31: Electrophotographic photosensitive member, 32: Charger, 33: Exposure light source, 34: Developer, 35: Transfer device, 36: Transfer paper, 37: Cleaning blade, 38: Charger

Claims (9)

An electrophotographic photoreceptor comprising a photosensitive layer containing at least a charge generator, an electron transport agent, and a binder resin on a substrate directly or via an intermediate layer,
The electrophotographic photoreceptor, wherein the electron transfer agent is a compound represented by the following general formula (1).

(In General Formula (1), R < ¹ > -R < ⁴ > is an independent substituent, respectively, a hydrogen atom, a C1-C12 substituted or unsubstituted alkyl group, a C1-C12 substituted or unsubstituted Or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, Ar is a phenanthryl group or a pyrenyl group. In the electron transport agent represented by the general formula (1), the electron mobility when the electric field strength is 5 × 10 ⁵ V / cm is 5 × 10 ^{−10 to} 5 × 10 ⁻⁷ cm ² / V / sec. 2. The electrophotographic photosensitive member according to claim 1, wherein the value is within a range.   The photosensitive layer is a single-layer photosensitive layer, and the content of the electron transfer agent represented by the general formula (1) is set to 0. 0 parts by weight with respect to 100 parts by weight of the binder resin in the single-layer photosensitive layer. The electrophotographic photosensitive member according to claim 1 or 2, wherein the value is within a range of 5 to 60 parts by weight.   The photosensitive layer is a multilayer photosensitive layer, and the content of the electron transfer agent represented by the general formula (1) in the charge generation layer included in the multilayer photosensitive layer is determined by binding in the charge generation layer. 3. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member has a value within a range of 1 to 90 parts by weight with respect to 100 parts by weight of the resin.   The content of the electron transport agent represented by the general formula (1) in the charge transport layer contained in the multilayer photosensitive layer is 0.05 to 80 weights with respect to 100 parts by weight of the binder resin in the charge transport layer. The electrophotographic photosensitive member according to claim 4, wherein the value is within a range of parts. The binder resin contains a polycarbonate resin represented by the following general formula (2), and a value obtained by dividing the inorganic degree in the polycarbonate resin by the organic degree (I / O value) is a value of 0.37 or more. The electrophotographic photosensitive member according to any one of claims 1 to 5, wherein
(In the general formula (2), a plurality of Ra and Rb are each an independent hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, and R ⁵ and R ⁶ is a different substituent, a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, W is a single bond or —O— or —CO—, and the repeating numbers k to 1 are independent of each other. The number of repetitions m and n is a molar ratio satisfying the relational expression of 0.05 <n / (n + m) <0.6.) The binder resin includes a polycarbonate resin represented by the following general formulas (3) and (4), or a polycarbonate resin represented by any one of claims 1 to 6. The electrophotographic photoreceptor described in 1.

(In General Formula (3), the plurality of substituents Rc are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms. The number o is an integer from 0 to 4.)

(In General Formula (4), a plurality of substituents Rd are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms. The number p is an integer from 0 to 4.) The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the photosensitive layer contains a compound represented by the following general formula (5) as an additive.

(In General Formula (5), R ^{7 to} R ¹⁶ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted carbon number 1 to 12. An alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, a hydroxyl group, R represents a substituted or unsubstituted alkylene group having 1 to 12 carbon atoms or an organic group containing a nitrogen atom, and n represents an integer of 0 to 3. )   The electrophotographic photosensitive member according to claim 1 is provided, and charging means, exposure means, developing means, and transfer means are arranged around the electrophotographic photosensitive member, respectively. Image forming apparatus.