JP2008134330A - Multilayer electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer electrophotographic photoreceptor capable of effectively suppressing the occurrence of photographic memories caused by eternal light and also holding excellent sensitivity properties, and to provide an image forming apparatus with the same. <P>SOLUTION: The multilayer electrophotographic photoreceptor includes a charge generating layer and a charge transport layer on a substrate. The charge transport layer contains an azine compound expressed by general formula (1) as an additive. In the general formula (1), R<SP>1</SP>and R<SP>2</SP>are independent, respectively, and are a 1 to 10C alkyl group, a 1 to 10C alkoxy group, a 6 to 30C substituted or unsubstituted aryl group or amino group; and Ar<SP>1</SP>and Ar<SP>2</SP>are independent, respectively, and are a 6 to 30C substituted or unsubstituted arylene group. The image forming apparatus is provided with the multilayer electrophotographic photoreceptor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer electrophotographic photosensitive member and an image forming apparatus. In particular, by adding an additive having a specific structure to the charge transport layer, it is possible to effectively suppress the occurrence of photo memory due to external light, while efficiently maintaining sensitivity characteristics. The present invention relates to a type electrophotographic photosensitive member and an image forming apparatus including the same.

Conventionally, as an electrophotographic photosensitive member used in an electrophotographic machine such as a copying machine or a laser printer, the photosensitive layer is made of an inorganic material such as amorphous silicon, and the photosensitive layer is made of a charge generating agent, a charge transporting agent, and a binder. Organic photoreceptors containing resins are known.
Among these electrophotographic photoreceptors, organic photoreceptors have excellent flexibility in structural design due to the variety of options for photosensitive materials such as charge generators and charge transport agents in addition to their ease of manufacture. Widely used. In addition, the organic photoconductor is roughly classified into a single layer type organic photoconductor and a multi-layer type organic photoconductor in terms of the layer structure. In particular, the multi-layer type organic photoconductor is functionally separated for each layer. Therefore, it is excellent in terms of design easiness and function control, and has been widely used in recent years.
However, since this multilayer organic photoreceptor contains a charge generating agent and a charge transporting agent in different layers, the charge transporting ability of the charge generating layer is likely to be reduced, and charges are accumulated inside the layer. There was a problem that the image characteristics deteriorated.
In particular, there has been a problem that charges generated by external light are accumulated in the charge generation layer and affect the uniformity of initial charging, so-called photo memory is likely to occur.

Therefore, in order to solve such a problem, a method is disclosed in which an additive for improving light resistance against external light is contained in the photosensitive layer (for example, see Patent Document 1).
More specifically, an electrophotographic photosensitive member is disclosed in which any one of the photosensitive layers contains an azobenzene derivative represented by the following general formula (32).

(In General Formula (32), Ar ³ and Ar ⁴ each independently represent an arylene group which may have a substituent having a substituent constant σ _m of a substituted benzene of 0.20 or less in the Hammett's relational rule, R ⁷ represents an amino group which may have a substituent, and R ⁸ represents an alkenyl group which may have a substituent.
JP 2005-15475 A (Claims)

  However, although the electrophotographic photosensitive member described in Patent Document 1 can suppress the generation of a photo memory to some extent, a sufficient effect can be obtained unless a large amount of azobenzene derivative is contained in the photosensitive layer. There was a problem that could not be. Further, due to such a large amount of azobenzene derivatives, there has been a problem that the sensitivity characteristics of the electrophotographic photosensitive member are liable to deteriorate.

Accordingly, the inventors of the present invention, as a result of intensive studies, have caused the generation of a photo memory by external light by including an azine compound having a specific structure in the charge transport layer of the multilayer electrophotographic photosensitive member. The inventors have found that excellent sensitivity characteristics can be maintained while being effectively suppressed, and have completed the present invention.
That is, the present invention provides a multilayer electrophotographic photosensitive member capable of effectively suppressing the generation of a photo memory due to external light and maintaining excellent sensitivity characteristics, and an image forming apparatus including the same. With the goal.

According to the present invention, there is provided a multilayer electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are provided on a substrate, and the charge transport layer is represented by the following general formula (1) as an additive. A laminated electrophotographic photosensitive member containing the azine compound is provided, and the above-mentioned problems can be solved.
That is, by adding the azine compound represented by the general formula (1) as an additive to the charge transport layer, even if the multilayer electrophotographic photosensitive member is exposed to external light, It is possible to efficiently absorb light and effectively suppress the generation of a photo memory.
On the other hand, despite the inclusion of an azine compound having such a specific structure in the charge transport layer, the charge transport agent suppresses the charge transport inhibitory effect to a minimum and provides excellent sensitivity characteristics. It can be held efficiently.

(In the general formula (1), R ¹ and R ² each are independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted 6 to 30 carbon atoms (It is an aryl group or an amino group, and Ar ¹ and Ar ² are each independently a substituted or unsubstituted arylene group having 6 to 30 carbon atoms.)

In constituting the multilayer electrophotographic photosensitive member of the present invention, when R ¹ or R ² is an amino group in the general formula (1), the amino group is represented by the following general formula (1 ′). It is preferable to have a structure.
By comprising in this way, while being able to absorb external light more efficiently, the charge transport capability of azine compound itself can be improved.

(In general formula (1 ′), R ³ and R ⁴ are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms.)

Further, in constituting the multilayer electrophotographic photosensitive member of the present invention, the content of the azine compound is set to a value within the range of 0.05 to 3 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer. It is preferable.
With this configuration, it is possible to further improve the balance between absorption of external light and retention of sensitivity characteristics.

In constituting the multilayer electrophotographic photosensitive member of the present invention, the binder resin in the charge transport layer contains a polycarbonate resin represented by the following general formula (2), and the inorganic value in the polycarbonate resin is set to an organic value. The value (I / O value) divided by the property value is preferably set to a value of 0.37 or more.
By comprising in this way, the dispersibility and stability of a charge transfer agent and the azine compound which has a specific structure can be improved. In addition, the stain resistance and wear resistance of the electrophotographic photosensitive member can be improved.

(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. And m and n are molar ratios satisfying the relational expression of 0.05 <n / (n + m) <0.6.)

In constituting the multilayer electrophotographic photosensitive member of the present invention, the binder resin in the charge transport layer is represented by the polycarbonate resin represented by the following general formulas (3) and (4), or any one of them. A polycarbonate resin is preferably included.
By comprising in this way, the dispersibility and stability of a charge transfer agent and the azine compound which has a specific structure can be improved more. Further, the stain resistance and wear resistance of the electrophotographic photoreceptor can be further improved.

(In the 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 30 carbon atoms. The number o is an integer from 0 to 4.)

(In the 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 30 carbon atoms. The number p is an integer from 0 to 4.)

In constituting the multilayer electrophotographic photosensitive member of the present invention, the charge transport layer preferably contains a hindered phenol antioxidant.
With this configuration, even when carrier traps are generated in the charge transport layer by external light and the space charge is accumulated in the charge transport layer, the space charge can be quickly returned to the ground state. it can.

In constituting the multilayer electrophotographic photosensitive member of the present invention, the charge transport layer preferably contains a biphenyl derivative represented by the following general formula (5) as another additive.
By comprising in this way, generation | occurrence | production of a crack can be prevented more effectively even if it is a case where a contamination component adheres with respect to an electrophotographic photoreceptor.

(In the general formula (5), a plurality of Re and Rf are each an independent hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and a phenyl group having 1 to 12 carbon atoms. (It is an integer of 5.)

In constituting the multilayer electrophotographic photosensitive member of the present invention, the charging type is preferably a negative charging type.
By configuring in this way, it becomes easier to use a hole transporting agent that is generally better in charge transporting ability than an electron transporting agent as a charge transporting agent, and thus effectively suppressing the occurrence of photo memory. However, the sensitivity characteristic can be further improved.

According to another aspect of the present invention, any one of the above-described laminated electrophotographic photosensitive members is provided, and a charging unit, an exposing unit, a developing unit, and a transferring unit are disposed around the laminated electrophotographic photosensitive member. An image forming apparatus characterized by the above.
That is, in the image forming apparatus of the present invention, since a specific laminated electrophotographic photosensitive member is mounted, generation of a photo memory can be effectively suppressed, while maintaining excellent sensitivity characteristics. be able to.

[First Embodiment]
The first embodiment of the present invention is a multilayer electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are provided on a substrate, and the charge transport layer has the general formula (1) as an additive. A laminated electrophotographic photosensitive member comprising an azine compound represented by the formula:
Hereinafter, it will be described in detail by dividing into each component.

1. Basic Configuration As shown in FIG. 1 (a), a multilayer electrophotographic photosensitive member 20 is formed by forming a charge generation layer 24 containing a charge generation agent on a substrate 12 by means of vapor deposition or coating, By applying an azine compound having a specific structure, a charge transporting agent, and the like, and a photosensitive layer coating solution containing a binder resin on the charge generation layer 24 and drying the same, the charge transport layer 22 is formed. Can be created.
In contrast to the above-described structure, as shown in FIG. 1B, 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
In general, the charge transport layer 22 preferably contains either a hole transport agent or an electron transport agent, but both a hole transport agent and an electron transport agent may be used.

In constituting the multilayer electrophotographic photosensitive member of the present invention, the multilayer electrophotographic photosensitive member is preferably a negatively charged type.
The reason for this is that by making the multilayer electrophotographic photosensitive member a negatively charged type, it is easy to use a hole transporting agent that is generally superior in charge transporting ability to the electron transporting agent as the charge transporting agent. This is because the sensitivity characteristics can be further improved while effectively suppressing the occurrence of photo memory.
In other words, the positive or negative charge type is selected depending on the order of forming the charge generation layer and the charge transport layer and the type of the charge transport agent used in the charge transport layer. As shown in FIG. 1A, when a charge generation layer 24 is formed on a substrate 12 and a charge transport layer 22 is formed thereon, an amine compound derivative is used as a charge transport agent in the charge transport layer 22. By using a hole transporting agent such as stilbene derivative or the like, the photoreceptor becomes a negatively charged type. In this case, the charge generation layer 24 may contain an electron transport agent. With such a negatively charged multilayer electrophotographic photosensitive member, it is possible to effectively reduce the residual potential in the photosensitive layer and improve the sensitivity characteristics.

  Further, as shown in FIG. 1C, it is also preferable to previously form the intermediate layer 25 on the substrate 12 before forming the photosensitive layer. The reason for this is that by providing such an intermediate layer 25, it is possible to prevent the charge on the substrate side from being easily injected into the photoreceptor layer, and to firmly bond the photoreceptor layer onto the substrate 12, thereby This is because the above defects can be covered and smoothed.

2. Substrate As the substrate on which the laminated photosensitive layer is formed, various conductive materials can be used. For example, a conductive substrate formed of a metal such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, anodized, and brass, Examples include a substrate made of a plastic material on which the above metal is deposited or laminated, or a glass substrate coated with aluminum iodide, tin oxide, indium oxide, or the like.
That is, it is only necessary that the substrate itself has conductivity or the surface of the substrate has conductivity. The conductive substrate is preferably one having sufficient mechanical strength when used.
The shape of the substrate may be any of a sheet shape and a drum shape according to the structure of the image forming apparatus to be used.

3. Intermediate Layer Further, as shown in FIG. 1C, an intermediate layer 25 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 by adding a predetermined fine powder in this intermediate layer, the incident light is scattered to suppress the generation of interference fringes, This is because charge injection from the substrate to the photosensitive layer during non-exposure that causes black spots can be suppressed. 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 to make the film thickness of this intermediate | middle layer into the value within the range of 0.1-50 micrometers. This is because if the intermediate layer thickness is too thick, a residual potential is likely to be generated on the surface of the electrophotographic photosensitive member, 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). Charge generation layer (1) Charge generation agent (1) -1 type In addition, examples of the charge generation agent in the present invention include phthalocyanine pigments such as metal-free phthalocyanine and oxotitanyl phthalocyanine, perylene pigments, bisazo pigments, diketo Pyrrolopyrrole pigment, metal-free naphthalocyanine pigment, metal naphthalocyanine pigment, squaraine pigment, trisazo pigment, indigo pigment, azulenium pigment, cyanine pigment, pyrylium pigment, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment Conventional photogenerators such as organic photoconductors such as pyrazoline pigments and quinacridone pigments, and inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon can be used.

(1) -2 Specific Example 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 a photoreceptor 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. It is.
On the other hand, when used in an analog optical image forming apparatus such as an electrostatic copying machine having a white light source such as a halogen lamp, a photosensitive member having sensitivity in the visible region is required. Perylene pigments and bisazo pigments can be preferably used.

(1) -3 Content Further, the content of the charge generating agent 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 constituting the charge generating layer.
The reason for this is that when the content is less than 5 parts by weight with respect to 100 parts by weight of the binder resin, the charge generation amount becomes insufficient and it becomes difficult to form a clear electrostatic latent image. This is because there are cases. On the other hand, when the content exceeds 1000 parts by weight with respect to 100 parts by weight of the binder resin, it may be difficult to form a uniform charge generation layer.
Therefore, the content of the charge generating agent with respect to 100 parts by weight of the binder resin constituting the charge generating layer is more preferably set to a value within the range of 30 to 500 parts by weight.

(2) Binder resin The binder resin used for the charge generation layer is polycarbonate resin such as bisphenol A type, bisphenol Z type or bisphenol C type, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polystyrene. Resin, polyvinyl acetate resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd Examples thereof include a single type of resin, N-vinylcarbazole, or a combination of two or more types.

(3) Thickness The thickness of the charge generation layer is preferably set to a value in the range of 0.1 to 5 μm.
This is because the amount of charge generated by exposure can be improved by setting the thickness of the charge generation layer to a value in the range of 0.1 to 5 μm.
That is, if the thickness of the charge generation layer is less than 0.1 μm, it may be difficult to form a charge generation layer having sufficient charge generation capability. On the other hand, if the thickness of the charge generation layer exceeds 5 μm, it may be difficult to suppress the generation of residual charges or it may be difficult to form a uniform charge generation layer.
Therefore, the thickness of the charge generation layer is more preferably set to a value within the range of 0.15 to 4 μm, and further preferably set to a value within the range of 0.2 to 3 μm.

5. Charge Transport Layer (1) Hole Transport Agent (1) -1 Type As the hole transport agent, conventionally known various hole transport compounds can be used. For example, a benzidine compound, a phenylenediamine compound, a naphthylenediamine compound, a phenanthrylenediamine compound, an oxadiazole compound (for example, 2,5-di (4-methylaminophenyl) -1,3,4) Oxadiazole etc.), styryl compounds (eg 9- (4-diethylaminostyryl) anthracene etc.), carbazole compounds (eg poly-N-vinylcarbazole etc.), organic polysilane compounds, pyrazoline compounds [eg 1-phenyl- 3- (p-dimethylaminophenyl) pyrazoline etc.], hydrazone compound, triphenylamine compound, indole compound, oxazole compound, isoxazole compound, thiazole compound, thiadiazole compound, imidazole compound, pyra Compounds, triazole compounds, butadiene compounds, pyrene-hydrazone compounds, acrolein compounds, carbazole-hydrazone compounds, quinoline-hydrazone compounds, stilbene compounds, stilbene-hydrazone compounds, and diphenylenediamine compounds A compound or the like is preferably used. These may be used alone or in combination of two or more.

(1) -2 Light absorption peak Moreover, it is preferable to make the light absorption peak in a hole transport agent into the value within the range of 350-400 nm.
This is because if the light absorption peak in the hole transport agent is less than 350 nm, the conjugated system in the molecule is excessively limited, and the predetermined hole transport ability may not be obtained. On the other hand, when the light absorption peak in the hole transport agent exceeds 400 nm, it overlaps with the light absorption peak of the azine compound having a specific structure described later, and the hole transport agent is actively caused by external light. This is because it may be easily affected by short wavelengths.
Therefore, the light absorption peak in the hole transport agent is more preferably set to a value within the range of 355 to 395 nm, and further preferably set to a value within the range of 360 to 390 nm.

(1) -3 Specific Example Among the hole transport agents described above, particularly preferable hole transport agents include compounds (HTM-1 to 4) represented by the following formulas (10) to (13). it can.

(1) -4 Content Further, the content of the hole transport agent is preferably set to a value within the range of 20 to 500 parts by weight with respect to 100 parts by weight of the binder resin, A value within the range is more preferable. In addition, when using a hole transporting agent and an electron transporting agent together, it is preferable to make the total amount into the value within the range of 20-500 weight part with respect to 100 weight part of binder resin, 30 More preferably, the value is in the range of ~ 200 parts by weight.

(2) Electron Transfer Agent (2) -1 Type As the electron transfer agent, any of various conventionally known electron transfer compounds can be used. In particular, benzoquinone compounds, diphenoquinone compounds, naphthoquinone compounds, malononitrile, thiopyran compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, fluorenone compounds (for example, 2,4,7-trinitro-9-fluorenone, etc.) ), Dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, succinic anhydride, maleic anhydride, dibromomaleic anhydride, 2,4,7-trinitrofluorenone imine compound, ethylated nitrofluorenone imine compound, tryptoan Thrin compound, tryptoanthrin imine compound, azafluorenone compound, dinitropyridoquinazoline compound, thioxanthene compound, 2-phenyl-1,4-benzoquinone compound, 2- Electrons such as salts of anion radicals and cations of phenyl-1,4-naphthoquinone compounds, 5,12-naphthacenequinone compounds, α-cyanostilbene compounds, 4, '-nitrostilbene compounds, and benzoquinone compounds Inhalable compounds are preferably used. These may be used alone or in combination of two or more.

(2) -2 Content Further, the content of the electron transport agent is preferably a value within the range of 20 to 500 parts by weight with respect to 100 parts by weight of the binder resin, and a range of 30 to 200 parts by weight. It is more preferable to set the value within the range. In addition, when using together an electron transport agent and the above-mentioned hole transport agent, it is preferable to make the total amount into the value within the range of 20-500 weight part with respect to 100 weight part of binder resin. More preferably, the value is within the range of 30 to 200 parts by weight.
Further, when the electron transport agent and the hole transport agent are used in combination, the content of the electron transport agent is set to a value within the range of 10 to 100 parts by weight with respect to 100 parts by weight of the hole transport agent. Is preferred.

(3) Additive 1
(3) -1 Type The multilayer electrophotographic photoreceptor of the present invention is characterized in that the charge transport layer contains an azine compound represented by the general formula (1) as an additive.
The reason for this is that even when the multilayer electrophotographic photosensitive member is exposed to external light by adding the azine compound represented by the general formula (1) as an additive to the charge transport layer, This is because such external light can be efficiently absorbed and generation of a photo memory can be effectively suppressed. On the other hand, despite the inclusion of an azine compound having such a specific structure with respect to the charge transport layer, the charge transport agent suppresses the charge transport inhibitory effect to a minimum, and exhibits excellent sensitivity characteristics. It is because it can hold efficiently.
That is, in the case of the azine compound represented by the general formula (1), the peak wavelength in light absorption is a value within a predetermined range and has excellent light absorption efficiency as will be described later. Therefore, it is possible to effectively suppress external light reaching the charge generation layer to generate charges and accumulate in the charge generation layer.
Therefore, it is possible to effectively suppress the occurrence of so-called photo memory, in which external light affects the uniformity of initial charging.
On the other hand, when the azine compound is contained in a charge transport layer in excess of a predetermined amount, charge transport by the charge transport agent may be inhibited. However, since the azine compound having a specific structure in the present invention has an excellent light absorption efficiency, even if the content is suppressed to a relatively small amount, a sufficient light shielding property can be exhibited. it can. Therefore, the inhibitory effect on the charge transport by the charge transport agent can be suppressed to the minimum, and excellent sensitivity characteristics can be efficiently maintained.
In addition, when R < ¹ > or R < ² > in General formula (1) is an alkyl group or an alkoxy group, it is more preferable to set carbon number in these substituents to 1-6, and it is more preferable to set it as 1-4. .

Further, in the general formula (1), when R ¹ or R ² is an amino group, the amino group preferably has a structure represented by the general formula (1 ′).
This is because, by making R ¹ or R ² in the general formula (1) an amino group having a specific structure, external light can be absorbed more efficiently and the charge transporting ability of the azine compound itself is improved. Because it can.
That is, by providing an amino group having such a specific structure, an azine compound having a specific structure can be more effectively excited by external light and can release its energy more stably. It is to become.
Further, since the amino group having such a specific structure is a triarylamine structure, it can also contribute to the improvement of the charge transport ability, particularly the hole transport ability of the azine compound.

(3) -2 Light absorption peak Moreover, it is preferable to make the light absorption peak in the azine compound which has a specific structure into the value within the range of 390-500 nm.
The reason for this is that even when the multilayer electrophotographic photosensitive member is exposed to external light having a much stronger light intensity than that of the exposure intensity and containing many short wavelengths, the external light is not charged. This is because it is possible to effectively suppress the generation of charges reaching up to and accumulation in the charge generation layer.
In addition, the charge transport agent in the charge transport layer can be prevented from changing to a carrier trap due to external light, and an increase in residual potential can be effectively suppressed.
Therefore, the occurrence of photo memory can be more effectively suppressed.
Note that when the peak wavelength of light absorption in the azine compound having a specific structure is less than 390 nm, it may be difficult to efficiently absorb light in a wavelength region that causes photo memory. On the other hand, when the peak wavelength in light absorption in the azine compound having a specific structure is a value exceeding 500 nm, light at the time of exposure is likely to be absorbed, and charge generation efficiency may be reduced.
Therefore, the light absorption peak wavelength in the azine compound having a specific structure is more preferably set to a value within the range of 395 to 480 nm, and further preferably set to a value within the range of 400 to 450 nm.
In addition, as an azine compound which has a specific structure whose light absorption peak is 390-500 nm, the compound (light absorption peak: 405.5 nm) represented by Formula (17) mentioned later is mentioned.

(3) -3 Specific Example Further, specific examples of the azine compound represented by the general formula (1) include compounds represented by the following formulas (14) to (17) (AZine-1 to 4). Can do.

(3) -4 Production Method In addition, as an example of the production method of the azine compound represented by the general formula (1), the production method of the azine compound (AZine-4) represented by the above-described formula (17) will be described. To do.
That is, it is preferable to manufacture the azine compound (AZine-4) represented by Formula (17) by the reaction shown in the following Reaction Formula (1).
That is, in toluene, in the presence of a compound represented by the formula (20), a formylated triarylamine derivative represented by the formula (18) and a hydrazine represented by the formula (19) It can be obtained by reacting.
In addition, it is preferable that reaction temperature shall be in the range of 80-120 degreeC, and reaction time shall be in the range of 0.2-3 hours.

(3) -5 Content In addition, the content of the azine compound having a specific structure may be set to a value in the range of 0.05 to 3 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer. preferable.
This is because the balance between absorption of external light and retention of sensitivity characteristics can be further improved by setting the content of the azine compound having a specific structure in such a range.
That is, when the content of the azine compound having a specific structure is less than 0.05 parts by weight, the charge transport layer cannot sufficiently absorb external light and effectively suppress the photo memory. This is because it may be difficult. On the other hand, when the content of the azine compound having a specific structure is a value exceeding 3 parts by weight, the inhibitory effect on the charge transport of the charge transport agent cannot be sufficiently suppressed, and the sensitivity characteristic may be deteriorated. Because. In addition, it is because white spots are likely to occur in the formed image.
Therefore, the content of the azine compound having a specific structure is more preferably set to a value within the range of 0.1 to 2 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 1 part by weight.

Next, the relationship between the content of an azine compound having a specific structure and the occurrence of a photomemory in the multilayer electrophotographic photoreceptor will be described with reference to FIGS.
In FIG. 2, the horizontal axis represents the content (parts by weight) of an azine compound having a specific structure with respect to 100 parts by weight of the binder resin of the charge transport layer, and the vertical axis represents a stack that was left in a 500 Lux room for 1 hour. A characteristic curve A is shown in which the evaluation score (relative value) of the occurrence of a photo memory when an image is formed immediately after being left using a type electrophotographic photosensitive member is shown.
In FIG. 3, the horizontal axis represents the content (parts by weight) of an azine compound having a specific structure with respect to 100 parts by weight of the binder resin of the charge transport layer, and the vertical axis represents 1 hour in a 500 Lux room. A characteristic curve B showing the evaluation point (relative value) of occurrence of a photo memory when an image is formed after recovering in a dark room for 24 hours after being left standing using the laminated electrophotographic photosensitive member is shown.
In addition, the azine compound (Azine-4) represented by Formula (17) was used as an azine compound which has a specific structure. In addition, the evaluation of occurrence of the photo memory is quantified according to the criteria of the evaluation points shown below. Further, the structure and the like of the laminated electrophotographic photoreceptor used are in accordance with the examples described later.
Evaluation point 3: No difference in image density is recognized between the images corresponding to the external light irradiation part and the light shielding part.
Evaluation point 2: Almost no difference in density is recognized between the images corresponding to the external light irradiation part and the light shielding part.
Evaluation point 1: A slight density difference is recognized between the images corresponding to the external light irradiation part and the light shielding part.
Evaluation point 0: A clear density difference is recognized between images corresponding to the external light irradiation part and the light shielding part.

As can be understood from the characteristic curve A, the generation of photomemory is rapidly suppressed as the content of the azine compound having a specific structure increases from 0 to 0.05 parts by weight. . And it turns out that generation | occurrence | production of a photomemory is completely suppressed in the range whose content of the azine compound which has a specific structure is 0.05 weight part or more.
Also in the characteristic curve B, when the content of the azine compound having a specific structure is in the range of 0 to 0.05 parts by weight, the generation of the photo memory is rapidly suppressed as the characteristic curve A is increased. ing. However, when the content of the azine compound having a specific structure exceeds 0.05 parts by weight, in the range of 3 parts by weight or less, the occurrence of photomemory can be completely suppressed as in the case of the characteristic curve A. It can be seen that when the amount exceeds 3 parts by weight, a photo memory (white spot) is suddenly generated.
Therefore, by setting the content of the azine compound having a specific structure to a value within the range of 0.05 to 3 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer, It turns out that generation | occurrence | production can be suppressed.

Next, the relationship between the content of the azine compound having a specific structure and the sensitivity characteristics in the multilayer electrophotographic photoreceptor will be described with reference to FIG.
In FIG. 4, the horizontal axis represents the content (parts by weight) of the azine compound having a specific structure with respect to 100 parts by weight of the binder resin of the charge transport layer, and the vertical axis represents the light potential in the multilayer electrophotographic photosensitive member. The characteristic curve which took the absolute value (V) of is shown. In addition, about the structure of the used laminated electrophotographic photoreceptor, the measuring method of a bright potential, etc., it applies to the Example mentioned later.
As understood from the characteristic curve, the absolute value of the light potential gradually increases as the content of the azine compound having a specific structure increases. This can be said to be because an azine compound having a specific structure basically has a property of inhibiting the charge transport by the charge transport agent.
However, it can be seen that when the content of the azine compound having a specific structure is in the range of 0 to 3 parts by weight, the light potential can be maintained at a low value around 40 V absolute value.
On the other hand, when the content of the azine compound having a specific structure exceeds 3 parts by weight, it is difficult to maintain the absolute value of the bright potential at a low value of around 40V.
Therefore, it can be seen that excellent sensitivity can be obtained by setting the content of the azine compound having a specific structure to a value of 3 parts by weight or less with respect to 100 weight parts of the binder resin in the charge transport layer.

(4) Binder Resin (4) -1 Type As the binder resin constituting the charge transport layer, various resins conventionally used in 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 not only excellent in transparency and heat resistance, but are also preferable because they are excellent in mechanical properties, charge transfer agents, and compatibility with azine compounds having a specific structure. Resin.

Further, as the above-described polycarbonate resin, in particular, a polycarbonate resin represented by the general formula (2) is used, and a value obtained by dividing the inorganic value in the polycarbonate resin by the organic value (I / O value) is 0. A value of .37 or more is preferable.
This is because the use of such a polycarbonate resin as a binder resin can improve the dispersibility and stability of the azine compound having the specific structure described above. Further, this is because the contamination resistance and wear resistance of the photoreceptor can be improved.
Therefore, the occurrence of cracks can be further reduced and the absorption of external light can be made more efficient even when repeatedly used for a long time or when finger oil adheres.
However, when the I / O value in such a polycarbonate resin becomes excessively large, the mixing property with an azine compound having a specific structure may be lowered.
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 azine compound having a specific structure can be further improved. Further, this is because the contamination resistance and wear resistance of the photoreceptor can be further improved.
That is, a polycarbonate resin having such a structure can adjust the balance among the electrical characteristics, abrasion resistance, contamination resistance, and the like of the photoreceptor 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 (2) 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.

(4) -2 Specific example Moreover, as a specific example of polycarbonate resin represented by General formula (2) mentioned above, polycarbonate resin (Resin-1 to 3) represented by following formula (21)-(23). Is mentioned.

  Specific examples of the polycarbonate resin represented by the general formulas (3) to (4) described above include polycarbonate resins (Resin-4 to 5) represented by the following formulas (24) to (25), respectively. It is done.

(5) Additive 2
(5) -1 Type In addition, the charge transport layer preferably contains a biphenyl derivative represented by the general formula (5) as another additive.
This is because, even when a contaminating component adheres to the photoconductor, the occurrence of cracks can be more effectively prevented by the action of the compound represented by the general formula (5).
That is, even when contamination components adhere to the surface of the electrophotographic photosensitive member, monomer components such as azine compounds and charge transport agents having a specific structure are eluted, and pores are formed inside the photosensitive layer, This is because the compound represented by the general formula (5) as an additive acts on the pores to release local stress and suppress the generation of cracks.

(5) -2 Specific Examples Specific examples of such additives include compounds (BP-1 to 5) represented by the following formulas (26) to (30).

(5) -3 Content Further, the content of the additive is preferably set to a value in the range of 1 to 15 parts by weight with respect to 100 parts by weight of the binder resin of the charge transport layer.
The reason for this is that when the content is less than 1 part by weight with respect to 100 parts by weight of the binder resin, the stress relaxation action as described above cannot be sufficiently exhibited, and the occurrence of cracks is sufficiently prevented. It is because it becomes impossible.
On the contrary, when the content exceeds 15 parts by weight, the glass transition point of the charge transport layer is lowered, the wear resistance is lowered, or the dispersibility in the binder resin is lowered, This is because crystallization occurs.
That is, when the content is a value within such a range, the wear resistance and stain resistance of the photosensitive layer can be obtained without excessively increasing the molecular weight of the binder resin. An electrophotographic photoreceptor excellent in productivity can be obtained.
Therefore, the content range is more preferably 2 to 12 parts by weight with respect to 100 parts by weight of the binder resin of the charge transport layer, and a value within the range of 3 to 10 parts by weight. More preferably.

(6) Antioxidant (6) -1 Type In addition, the charge transport layer preferably contains a hindered phenol-based antioxidant.
This is because even when the charge transport layer contains a hindered phenol-based antioxidant, carrier traps are generated in the charge transport layer due to external light, and space charges accumulate in the charge transport layer. This is because such space charge can be quickly returned to the ground state.

(6) -2 Specific Example Specific examples of the hindered phenol antioxidant include compounds (P-1 to 16) represented by the following formula (31).

(6) -3 Content In addition, the content of the antioxidant is preferably set to a value in the range of 1 to 40 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer.
The reason for this is that when the content is less than 1 part by weight with respect to 100 parts by weight of the binder resin in the charge transport layer, the effect of suppressing the photo memory may not be sufficiently exhibited. On the other hand, when the content exceeds 40 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer, it may be difficult to uniformly disperse in the charge transport layer. .
Therefore, it is more preferable to set the content of the antioxidant to a value within the range of 3 to 35 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer, and within a range of 5 to 30 parts by weight. More preferably, it is a value.

(7) Thickness The thickness of the charge transport layer is preferably set to a value in the range of 0.1 to 50 μm.
This is because when the thickness of the charge transport layer is less than 0.1 μm, the mechanical strength may be significantly reduced. On the other hand, when the thickness of the charge transport layer exceeds 50 μm, it may be difficult to form a uniform film thickness or the layer may be easily peeled off.
Therefore, the thickness of the charge transport layer is more preferably set to a value within the range of 1 to 30 μm.

6). Manufacturing Method Regarding the manufacturing method of the multilayer photoreceptor layer of the present invention, a charge transport layer coating solution and a charge generation layer coating solution are prepared as described below, applied onto a substrate, and then dried. It is preferable to manufacture.

(1) Coating liquid preparation process The coating liquid preparation process includes, for example, a coating liquid for a charge transport layer, and a binder resin, which includes a binder resin, an azine compound having a specific structure, a charge transport agent, and a solvent. And a charge generation layer coating solution comprising a charge generation agent and a solvent. For example, it is preferable to disperse and mix using a roll mill, a ball mill, an attritor, a paint shaker, an ultrasonic disperser or the like to obtain a coating solution.
More specifically, the solid content concentration of the charge transport layer coating solution is within the range of 10 to 30% by weight, and the solid content concentration of the charge generation layer coating solution is within the range of 1 to 10% by weight. It is preferable to prepare a coating solution. The reason for this is that if the solid content concentration of the coating solution for the charge transport layer is less than 10% by weight, a coating defect may occur, whereas the solid content concentration of the coating solution exceeds 30% by weight. This is because unevenness of layers is likely to occur, and it may be difficult to form a thin film having a uniform thickness as a photoreceptor. Similarly, if the solid content concentration of the coating solution for the charge generation layer is less than 1% by weight, film defects may occur. If the solid content concentration exceeds 10% by weight, unevenness of the layer is likely to occur. It may be difficult to form a thin film having a uniform thickness as a body.
Various organic solvents can be used as the solvent for preparing the charge transport layer coating solution and the charge generation layer coating solution. 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, dichloromethane, dichloroethane, chloroform and tetrachloride Halogenated hydrocarbons such as carbon and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dioxane and dioxolane; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Class, dimethylformaldehyde, dimethylformamide, dimethylsulfoxide, etc., alone or in combination of two or more. That.
Furthermore, in order to improve the dispersibility of the charge transport agent, the charge generator, etc. and the smoothness on the surface of the photoreceptor layer, it is also preferable to add a surfactant, a leveling agent or the like when preparing the coating solution.

(2) Coating step and drying step The first coating step and the first drying step, the second coating step and the second drying step may be provided to form a photoreceptor layer comprising a charge transport layer and a charge generation layer. preferable. For example, as shown in FIG. 1A, the charge generation layer 24 is formed on the substrate 12 by the first coating process and the first drying process, and then, by the second coating process and the second drying process, It is preferable to form the charge transport layer 22 on the charge generation layer 24.

(2) -1 Application Step In carrying out the application step, it is also preferable to apply the application liquid directly on the substrate, or to apply it indirectly via an intermediate layer.
As a coating method, it is preferable to use, for example, a spin coater, an applicator, a spray coater, a bar coater, a dip coater, a doctor blade, etc., in order to form a photoreceptor layer having a uniform thickness.
The charge generation layer preferably has a thinner coating than the charge transport layer in order to reduce the residual potential.

(2) -2 Drying step Further, after the coating step, in the drying step, it is preferable to dry at a drying temperature of, for example, 60 ° C. to 150 ° C. using a high-temperature dryer, a vacuum dryer, or the like. This is because when the drying temperature is less than 60 ° C., the drying time becomes excessively long, and it may be difficult to efficiently form a photoreceptor layer having a uniform thickness. is there. On the other hand, if the drying temperature exceeds 150 ° C., the photoconductor may be thermally decomposed.

[Second Embodiment]
The second embodiment includes the multilayer 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 multilayer electrophotographic photosensitive member. The image forming apparatus is characterized.
Hereinafter, the contents already described in the first embodiment will be omitted, and the image forming apparatus as the second embodiment will be described focusing on differences from the first embodiment.

  In carrying out the image forming method of the second embodiment, a copying machine 40 that is an image forming apparatus as shown in FIG. 5 can be preferably used. The copying machine 40 includes an image forming unit 41, a paper discharge unit 42, an image reading unit 43, and a document feeding unit 44. The image forming unit 41 further includes an image forming unit 41a and a paper feeding unit 41b. In the illustrated example, the document feeding unit 44 includes a document placing tray 44a, a document feeding mechanism 44b, and a document discharge tray 44c, and the document placed on the document placing tray 44a. Is sent to the image reading position P by the document feeding mechanism 44b and then discharged to the document discharge tray 44c.

Then, when the document is sent to the document reading position P, the image reading unit 43 reads the image on the document using the light from the light source 43a. That is, an image signal corresponding to the image on the document is formed using an optical element 43b such as a CCD.
On the other hand, recording sheets (hereinafter simply referred to as “sheets”) S stacked on the sheet feeding unit 41b are sent one by one to the image forming unit 41a. The image forming unit 41a is provided with a photosensitive drum 51 as an image carrier, and around the photosensitive drum 51, a charger 52, an exposure unit 53, a developing unit 54, and a transfer roller. 55 and a cleaning device 56 are arranged along the rotation direction of the photosensitive drum 51.

  Among these components, the photosensitive drum 51 is rotationally driven in the direction indicated by the solid line arrow in the drawing, and the surface thereof is uniformly charged by the charger 52. Thereafter, an exposure process is performed on the photosensitive drum 51 by the exposure device 53 based on the above-described image signal, and an electrostatic latent image is formed on the surface of the photosensitive drum 51. Based on the electrostatic latent image, the developing device 54 attaches toner and develops it, thereby forming a toner image on the surface of the photosensitive drum 51. The toner image is transferred as a transfer image onto the sheet S conveyed to the nip portion between the photosensitive drum 51 and the transfer roller 55. Next, the sheet S on which the transferred image is transferred is conveyed to the fixing unit 57 and a fixing process is performed.

Here, the paper S after fixing is sent to the paper discharge unit 42. However, when performing post-processing (for example, stapling processing), the paper S is sent to the intermediate tray 42a and then back. Processing is performed. Thereafter, the sheet S is discharged to a discharge tray portion (not shown) provided on the side surface of the image forming apparatus. On the other hand, when no post-processing is performed, the sheet S is discharged to a discharge tray 42b provided below the intermediate tray 42a.
The intermediate tray 42a and the paper discharge tray 42b are configured as a so-called in-body paper discharge unit.
After the transfer is performed as described above, the residual toner (and paper dust) remaining on the photosensitive drum 51 is removed by the cleaning device 56. That is, while the photosensitive drum 51 is cleaned, residual toner is collected in a waste toner container (not shown).

In the image forming apparatus of the present invention, since a specific laminated electrophotographic photosensitive member is mounted, generation of a photo memory can be effectively suppressed, while maintaining excellent sensitivity characteristics. be able to.
Therefore, with the image device according to the present invention, it is possible to stably form a clear image with little generation of photo memory.

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

[Example 1]
1. Production of multilayer electrophotographic photoreceptor (1) Formation of intermediate layer Using a paint shaker, surface treatment was performed with titanium oxide (MT-02, alumina and silica, and then with methyl hydrogen polysiloxane. Number average primary particle size 10 nm (manufactured by Teica)) 250 parts by weight, quaternary copolymerized polyamide resin CM8000 (manufactured by Toray) 100 parts by weight, solvent 1000 parts by weight, and n-butanol 250 parts by weight for 10 hours After mixing and dispersing, and further filtering through a 5 micron filter, an intermediate layer coating solution was prepared.
Next, one end of an aluminum substrate (supporting substrate) having a diameter of 30 mm and a length of 238.5 mm was placed on the upper side, and the resultant was applied by being immersed in the obtained intermediate layer coating solution at a rate of 5 mm / sec. Then, the hardening process was performed on 130 degreeC and the conditions for 30 minutes, and the intermediate layer with a film thickness of 2 micrometers was formed.

(2) Formation of charge generation layer Next, using a bead mill, 200 parts by weight of titanyl phthalocyanine (CGM-1) crystals represented by formula (6) as a charge generation agent and polyvinyl butyral resin (Binder resin) ( 100 parts by weight of Denka Butyral # 6000EP manufactured by Denki Kagaku Kogyo Co., Ltd., 4000 parts by weight of propylene glycol monomethyl ether and 4000 parts by weight of tetrahydrofuran as a dispersion medium are mixed and dispersed for 48 hours to obtain a coating solution for the charge generation layer. It was. The obtained coating solution is filtered through a 3 micron filter, and then applied onto the above-described intermediate layer by dip coating, and dried at 80 ° C. for 5 minutes to form a charge generation layer having a thickness of 0.3 μm. did.

(3) Formation of charge transport layer Next, in the ultrasonic disperser, 70 parts by weight of the compound (HTM-1) represented by the formula (10) as a hole transport agent and the formula (14) as an additive are represented. 0.5 parts by weight of azine compound (Azine-1), 10 parts by weight of metaterphenyl (BP-1) represented by formula (26) as other additives, and formula (31) as an antioxidant 4 parts by weight of IRGANOX 1010 (P-14), 70 parts by weight of a polycarbonate resin (Resin-1) having a viscosity average molecular weight of 20,500 represented by formula (21) as a binder resin, and formula (23) After accommodating 30 parts by weight of a polycarbonate resin (Resin-3) having a viscosity average molecular weight of 50,000, 300 parts by weight of tetrahydrofuran as a solvent, and 300 parts by weight of toluene, Dispersion treatment was carried out for 10 minutes to obtain a charge transport layer coating solution.
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, and dried at 120 ° C. for 30 minutes to form a charge transport layer having a thickness of 20 μm. A photoconductor was prepared.

(4) Production of titanyl phthalocyanine crystal In addition, the titanyl phthalocyanine crystal contained in the charge generation layer as a charge generation agent was produced as follows.
That is, 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, the temperature of the system was raised to 215 ° C. while distilling off the vapor generated from the reaction system, and the mixture was further stirred for 2 hours while maintaining this temperature.
Then, after the reaction is completed, when the reaction mixture is cooled to 150 ° C., the reaction mixture is taken out of the flask, filtered through a glass filter, and the resulting solid is washed successively with N, N-dimethylformamide and methanol and then vacuum-dried. As a result, 25 g of a blue-violet solid was obtained.

Next, as a pre-pigmentation treatment, 15 g of the blue-violet solid obtained in the production of the above-mentioned titanyl phthalocyanine compound was added to 100 ml of N, N-dimethylformamide, and heated to 130 ° C. with stirring for 2 hours. Stir processing was performed.
Next, the heating was stopped when 2 hours passed, and further the stirring was stopped when the temperature was cooled to 23 ± 1 ° C. In this state, the liquid was allowed to stand for 12 hours for stabilization treatment. The stabilized supernatant was filtered off with a glass filter, and the resulting solid was washed with methanol and then vacuum dried to obtain 9.83 g of a crude crystal of a titanyl phthalocyanine compound.

Next, as a pigmentation treatment, 5 g of the crude crystal of titanyl phthalocyanine obtained by the above-mentioned pigmentation pretreatment was added to 100 ml of concentrated sulfuric acid and dissolved.
Next, this solution was dropped into water under ice cooling, stirred at room temperature for 15 minutes, and further allowed to stand at 23 ± 1 ° C. for 30 minutes to recrystallize and separate from the supernatant.
Next, the supernatant is filtered off with a glass filter, and the resulting solid is washed with water until the washing solution becomes neutral. Then, without drying, it is dispersed in 200 ml of chlorobenzene and heated to 50 ° C. And stirred for 10 hours. The supernatant was filtered off with a glass filter, and the obtained crystals were vacuum-dried at 50 ° C. for 5 hours to obtain 4.5 g of unsubstituted titanyl phthalocyanine crystals (blue powder) represented by the formula (6). Got.
In the obtained titanyl phthalocyanine crystal, as an optical characteristic, the Bragg angle 2θ ± 0 .0 .0 in the CuKα characteristic X-ray diffraction spectrum was obtained in the initial stage and after being immersed in 1,3-dioxolane or tetrahydrofuran for 7 days. It was confirmed that no peaks occurred at 2 ° = 7.4 ° and 26.2 °. In addition, as a thermal characteristic, it was confirmed that a temperature change peak at only one location at 302 ° C. was observed in addition to a peak near 90 ° C. accompanying vaporization of adsorbed water when the temperature was raised to 400 ° C. in differential scanning calorimetry. .

2. Evaluation (1) Evaluation of Photo Memory Generation Evaluation of photo memory generation in the obtained multilayer electrophotographic photosensitive member was performed.
That is, the obtained multilayer electrophotographic photosensitive member was left in a room with a luminous intensity of 500 Lux for 1 hour in a state where it was partially shielded from light. Next, the laminated electrophotographic photoreceptor immediately after being left was mounted on a printer (Microline-22N, manufactured by Oki Data Corporation) using a negative charge reversal development process to form a gray image. Next, the obtained gray images were visually inspected for density differences in portions corresponding to the external light irradiation portion and the light shielding portion of the multilayer electrophotographic photosensitive member, and evaluated according to the following criteria.
In addition, a laminated electrophotographic photosensitive member that was left in a room with a luminous intensity of 500 Lux for 1 hour and then recovered in a dark room for 24 hours was similarly mounted on a printer to form an image and generate photo memory. Was evaluated. The obtained results are shown in Table 2.
A: No difference in image density is recognized between images corresponding to the external light irradiation part and the light shielding part.
○: Almost no difference in density is recognized between the images corresponding to the external light irradiation part and the light shielding part.
Δ: A slight density difference is recognized between the external light irradiation part and the image corresponding to the irradiation part.
X: A clear density difference is recognized between the images corresponding to the external light irradiation part and the light shielding part.

(2) Evaluation of light potential Further, the light potential of the obtained multilayer electrophotographic photosensitive member was evaluated.
That is, the developing means is removed from the imaging unit in the printer (Okidata MicroLine-22 manufactured by Oki Data Co., Ltd.) that employs the negatively charged reversal development process, and a potential measuring device is attached thereto to create an imaging unit for measuring potential. did. 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 above-described imaging for potential measurement is performed on the laminated electrophotographic photoreceptor after printing 10,000 sheets with a 1% original in a normal temperature and humidity environment (temperature: 23 ° C., relative humidity: 50% RH). The unit was attached to the unit and negatively charged, and the charging potential at this time was measured. Next, exposure corresponding to a solid black image was performed, and the potential of the exposed portion was measured. In addition, although the obtained measured value was a negative value, the absolute value (positive value) was made into the light potential (V). The obtained results are shown in Table 2.

[Example 2]
In Example 2, a laminated electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the azine compound (AZine-2) represented by the formula (15) was used as the azine compound having a specific structure. And evaluated. The obtained results are shown in Table 2.

[Example 3]
In Example 3, a laminated electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the azine compound (AZine-3) represented by the formula (16) was used as the azine compound having a specific structure. And evaluated. The obtained results are shown in Table 2.

[Example 4]
For Example 4, a laminated electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the azine compound (AZine-4) represented by the formula (17) was used as the azine compound having a specific structure. And evaluated. The obtained results are shown in Table 2.

[Example 5]
In Example 5, a laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the compound (HTM-2) represented by the formula (11) was used as the hole transport agent. The obtained results are shown in Table 2.

[Example 6]
In Example 6, a laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the compound (HTM-3) represented by the formula (12) was used as the hole transport agent. The obtained results are shown in Table 2.

[Example 7]
In Example 7, a laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the compound (HTM-4) represented by the formula (13) was used as the hole transport agent. The obtained results are shown in Table 2.

[Example 8]
In Example 8, a laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the compound (CGM-2) represented by the formula (7) was used as the charge generator. The obtained results are shown in Table 2.

[Example 9]
In Example 9, as a binder resin in the charge transport layer, 70 parts by weight of a polycarbonate resin (Resin-2) represented by the formula (22) and a polycarbonate resin (Resin-3) represented by the formula (23) A laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that 30 parts by weight was used. The obtained results are shown in Table 2.

[Example 10]
In Example 10, as a binder resin in the charge transport layer, 70 parts by weight of a polycarbonate resin (Resin-1) represented by the formula (21) and a polycarbonate resin (Resin-4) represented by the formula (24) A laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that 30 parts by weight was used. The obtained results are shown in Table 2.

[Example 11]
In Example 11, as a binder resin in the charge transport layer, 70 parts by weight of a polycarbonate resin (Resin-2) represented by the formula (22) and a polycarbonate resin (Resin-4) represented by the formula (24) A laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that 30 parts by weight was used. The obtained results are shown in Table 2.

[Examples 12 to 20]
In Examples 12 to 20, a multilayer electrophotographic photosensitive member was prepared in the same manner as in Example 4 except that the content of the azine compound relative to 100 parts by weight of the binder resin in the charge transport layer was changed as shown in Table 2. Made and evaluated. The obtained results are shown in Table 2.

[Comparative Examples 1-4]
In Comparative Examples 1 to 4, a laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Examples 1 and 5 to 7 except that an azine compound having a specific structure was not contained. The obtained results are shown in Table 2.

[Comparative Example 5]
In Comparative Example 5, 70 parts by weight of the azine compound (Azine-1) represented by the formula (14) is contained instead of 70 parts by weight of the hole transporting agent (HTM-1) represented by the formula (10). A laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Comparative Example 1 except that it was made. The obtained results are shown in Table 2.

According to the multilayer electrophotographic photosensitive member and the image forming apparatus using the same according to the present invention, by adding an azine compound having a specific structure to the charge transport layer of the multilayer electrophotographic photosensitive member, While the generation of photo memory due to light can be effectively suppressed, excellent sensitivity characteristics can be maintained.
Therefore, the multilayer electrophotographic photosensitive member of the present invention and the image forming apparatus using the same not only improve the performance of various image forming apparatuses such as a copying base and a printer, but also handle the multilayer electrophotographic photosensitive member. Further, it is expected to contribute significantly to simplification of the assembly operation of the image forming apparatus.

(A)-(c) is a figure provided in order to demonstrate the structure of a laminated type electrophotographic photoreceptor. It is a figure provided in order to demonstrate the relationship between content of an azine compound and the generation | occurrence | production evaluation score of a photo memory. It is another figure provided in order to demonstrate the relationship between content of an azine compound and the generation | occurrence | production evaluation score of a photo memory. It is a figure provided in order to demonstrate the relationship between content of an azine compound and a bright potential. It is a figure provided in order to demonstrate the image forming apparatus provided with the lamination type electrophotographic photosensitive member.

Explanation of symbols

20: Laminated photoreceptor 20 ′: Laminated photoreceptor 20 ″: Laminated photoreceptor 22: Charge transport layer 24: Charge generation layer 25: Intermediate layer 40: Copying machine 41: Image forming unit 41a: Image forming section 41b : Paper feed unit 42: Paper discharge unit 43: Image reading unit 43 a: Light source 43 b: Optical element 44: Document feeding unit 44 a: Document loading tray 44 b: Document feeding mechanism 44 c: Document discharge tray 51: Photosensitive drum 52 : Charger 53: Exposure source 54: Developer 55: Transfer roller 56: Cleaning device 57: Fixing unit

Claims (9)

A laminated electrophotographic photosensitive member provided with a charge generation layer and a charge transport layer on a substrate,
The charge transport layer contains an azine compound represented by the following general formula (1) as an additive.

(In the general formula (1), R ¹ and R ² each are independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted 6 to 30 carbon atoms (It is an aryl group or an amino group, and Ar ¹ and Ar ² are each independently a substituted or unsubstituted arylene group having 6 to 30 carbon atoms.) The R ¹ or R ² in the general formula (1) is an amino group, and the amino group has a structure represented by the following general formula (1 ′). Multilayer electrophotographic photoreceptor.

(In general formula (1 ′), R ³ and R ⁴ are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms.)   The laminated type according to claim 1 or 2, wherein the content of the azine compound is set to a value within a range of 0.05 to 3 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer. Electrophotographic photoreceptor. The binder resin in the charge transport layer contains a polycarbonate resin represented by the following general formula (2), and a value obtained by dividing the inorganic value in the polycarbonate resin by the organic value (I / O value) is 0.00. The multilayer electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the value is 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. And m and n are molar ratios satisfying the relational expression of 0.05 <n / (n + m) <0.6.) The binder resin in the charge transport layer 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 4. The multilayer electrophotographic photosensitive member according to any one of the above.

(In the 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 30 carbon atoms. The number o is an integer from 0 to 4.)

(In the 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 30 carbon atoms. The number p is an integer from 0 to 4.)   The multilayer electrophotographic photoreceptor according to any one of claims 1 to 5, wherein the charge transport layer contains a hindered phenol-based antioxidant. The multilayer electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the charge transport layer contains a biphenyl derivative represented by the following general formula (5) as another additive. .

(In the general formula (5), a plurality of Re and Rf are each an independent hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and a phenyl group having 1 to 12 carbon atoms. (It is an integer of 5.)   The multilayer electrophotographic photosensitive member according to any one of claims 1 to 7, wherein the multilayer electrophotographic photosensitive member is a negatively charged type.   A multilayer electrophotographic photosensitive member according to any one of claims 1 to 8, and a charging unit, an exposure unit, a developing unit, and a transfer unit are arranged around the multilayer electrophotographic photosensitive member. An image forming apparatus.

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