JPH112907A - Electrophotographic photoreceptor and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an S-shaped electrophotographic photoreceptor high in performance high in the sensitivity of light, low in residual potential and excellent in electrophotographic characteristic and to provide a digital electrophotographic device utilizing the photoreceptor. SOLUTION: This photoreceptor is provided with at least a charge generation layer 2 and a charge transportation layer 5 on an electrical conductive substrate 1. The layer 5 is provided with a nonuniform charge transportation layer 3 which is a phase separation state having modulation structure consisting of a charge transporting phase and an electrically inactive phase and includes a block copolymer consisting of a charge transporting block and an insulating block or a graft copolymer. Then, exposure required for attenuating 50% potential of the photoreceptor is not more 5 times of the exposure required for attenuating 10% potential. The layer 5 may be provided with also a uniform charge transportation layer 4, and an undercoating layer may be formed on the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor including a conductive substrate, a charge generation layer and a charge transport layer.
In particular, the present invention relates to an electrophotographic photosensitive member suitable for digital electrophotography. Further, the present invention relates to a digital electrophotographic apparatus using these electrophotographic photosensitive members.

[0002]

2. Description of the Related Art In recent years, electrophotographic technology has played a central role in the fields of copiers, printers, facsimile machines and the like because of its advantages such as high speed and high printing quality.

As an electrophotographic photoreceptor used in the electrophotographic technology, one using an inorganic photoconductive material such as selenium, a selenium-tellurium alloy, or a selenium-arsenic alloy has been widely known. On the other hand, research on electrophotographic photoreceptors using organic photoconductive materials, which have advantages in terms of cost, manufacturability, disposability, etc., compared with these inorganic photoreceptors, has also become active. It has surpassed the body.

[0004] In particular, the development of a function-separated layered structure in which photocharge generation and charge transport, which are the elementary processes of photoconduction, are carried out in separate layers has been developed. At present, this function-separated and laminated organic photoreceptor has become the mainstream of electrophotographic photoreceptors. The charge generation layer for the function-separated laminated organic photoreceptor is formed by directly depositing a pigment having a charge generation ability such as a quinone pigment, a perylene pigment, an azo pigment, a phthalocyanine pigment, or selenium by vapor deposition or the like. Alternatively, those having a high concentration dispersed in a binder resin have been put to practical use. On the other hand, as the charge transporting layer, a layer in which a low-molecular compound having a charge transporting property such as a hydrazone compound, a benzidine compound, an amine compound, or a stilbene compound is molecularly dispersed in an insulating resin is used.

Conventionally, as a photosensitive member used in an analog type electrophotographic copying machine that optically forms an image of a document on a photosensitive member and exposes the original, the reproducibility of halftones based on density gradation is improved. For this purpose, a photoreceptor having a photo-induced potential decay characteristic as shown in FIG. 1, that is, a photoreceptor which causes a potential decay in proportion to the amount of exposure (hereinafter referred to as a "J-shaped photoreceptor") is required. You. The above-mentioned inorganic photoconductors and function-separated stacked organic photoconductors all exhibit photoinduced potential decay characteristics falling within this category. However, digital electrophotographic apparatuses, which have been actively researched and developed in response to recent demands for higher image quality, higher added value, networking, etc., generally require an area scale that produces gradation at an area ratio of dots or the like. As shown in FIG. 2, the potential is not attenuated until a certain amount of exposure is reached, and a sharp potential decay occurs when the amount of exposure is exceeded. (Hereinafter, referred to as an “S-shaped photoconductor”) is desirable from the viewpoint of increasing the sharpness of pixels.

The S-shaped photoinduced potential decay characteristic is a known phenomenon in a single-layer type photoreceptor in which an inorganic pigment such as ZnO or an organic pigment such as phthalocyanine is dispersed in a resin. M. Schaffert: "Elect
rophotography ", Focal Pres
s, p. 344 (1975); W. Weigl,
J. Mammino, G .; L. Whitaker,
R. W. Radler, J .; F. Byrne: "Cur
rent Problems in Electrotrope
photography, Walter de Gru
yter, p. 287 (1972)]. In particular, there have been proposed a large number of single-layer photoreceptors for laser exposure in which a phthalocyanine-based pigment having photosensitivity in the near-infrared region, which is a wavelength of a semiconductor laser that is widely used at present, is dispersed in a resin [for example, Nguyen Chang].・ K, Aizawa; Journal of the Chemical Society of Japan, p.
393 (1986), JP-A-1-169454,
2-207258, 3-31847, 5-313
387]. However, these single-layer photoreceptors need to have both functions of charge generation and charge transport with a single material, but materials that have excellent performance in both functions are rare, and those that can withstand practical use are still not available. Not obtained. In particular, since pigment particles generally have many trap levels, they have drawbacks such as low charge transport ability and residual charges, and are not suitable for charge transfer. The only exceptional practical example is a ZnO resin dispersed single layer photoreceptor,
It is used as a master plate for offset printing that forms a plate by the area gradation method based on the presence or absence of hydrophobic toner utilizing the hydrophilicity of nO [for example, Kawamura "Basic and Application of Electrophotography", Electrophotography Academic Society, Corona, p. 4
24 (1988)]. However, this is also a successful example because it was used as a master plate with a low demand for high speed and printing durability, and to a level that can withstand practical use as a photoreceptor used in copying machines, printers, and the like that are used in the present invention. Absent. From these viewpoints, in the case of the S-shaped photoreceptor, it is desired to introduce a function-separated type layer configuration in order to increase the degree of freedom in material selection and, consequently, to improve overall photoreceptor characteristics.

To solve this problem, D.S. M. Pai et al. In a laminated photoreceptor comprising a charge generation layer and a charge transport layer,
By using a heterogeneous charge transport layer comprising at least two charge transport regions and one electrically inactive region as the charge transport layer, wherein the charge transport regions are in contact with each other to form a convoluted charge transport path, It has been reported that an S-shaped photo-induced potential decay characteristic can be realized in combination with an arbitrary charge generation layer [Japanese Patent Laid-Open No. Hei 6-83077 (US Pat.
306586 specification)].

In this report, as a method for manufacturing a heterogeneous charge transport layer in which charge transport regions are in contact with each other to form a convoluted charge transport path, inorganic or organic particles or microcrystals capable of transporting charge are used. A method for producing a non-uniform charge transport layer immersed in an insulating polymer, or producing a charge transport layer from a solid solution of charge transport molecules in a polymer binder and, for example, crystallizing one of the phases And a method for producing a charge transport block from a block copolymer surrounded by an untransport block.

However, since the inorganic or organic particles or microcrystals capable of transporting charge generally have many trap levels, the inorganic or organic particles or microcrystals capable of transporting charge are immersed in the insulating polymer. In the method for producing a non-uniform charge transport layer, the charge transport ability is low,
There are drawbacks such as residual charges. Further, in a method for producing a charge transport layer from a solid solution of charge transport molecules in a polymer binder and, for example, producing the charge transport layer by crystallizing one of the phases, since a compound satisfying the above conditions is rare,
This is a major obstacle in designing a photoconductor that can withstand practical use. Furthermore, although the method for producing the charge transport block from the block copolymer surrounded by the non-transport block does not have the above-described problems, the charge transport speed is improved by securing the charge transport path, the residual potential is reduced, It is difficult to achieve a balance between characteristics such as repetition stability and the like and S-shaped property. If the number of charge transport blocks is increased and a charge transport path is secured, the S-shaped property deteriorates, the number of charge transport blocks is reduced, and the S-shaped property is improved. If this is attempted, the charge transport path is cut off, so that the charge transport speed decreases, the residual potential increases, the repetition stability deteriorates, and the like, and it has been difficult to obtain a good photoreceptor having both of the above characteristics.

In order to solve such a problem, the present inventors have proposed that a charge transport layer contains a polymer compound in a phase separation state composed of an electrically inactive phase having a modulation structure and a charge transporting phase. The body was proposed (Japanese Patent Application No. 8-158520). The present invention provides a heterogeneous charge transporting layer in a phase separation state comprising an electrically inactive phase having this modulation structure and a charge transporting phase, in which the size of the phase in the phase separation state is not easily affected by manufacturing conditions. And further optimization.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances in the prior art, and has a novel S-shaped photoreceptor capable of overcoming the above problems. It is intended to provide.

That is, an object of the present invention is to provide a high-performance S-shaped photoreceptor excellent in electrophotographic characteristics in an electrophotographic photoreceptor including at least a conductive substrate, a charge generation layer and a charge transport layer. It is in. It is another object of the present invention to provide a digital electrophotographic apparatus using a high-performance S-shaped photoreceptor.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is to provide an electrophotographic photoreceptor having a charge generation layer and a charge transport layer provided on a conductive substrate. In a phase-separated state having a modulation structure composed of the following phases: a block copolymer or a graft copolymer composed of a charge transporting block and an insulating block; and an exposure amount required for 50% potential decay is 10% potential decay. Of exposure required for
The problem is solved by an electrophotographic photosensitive member characterized in that the ratio is less than twice.

The modulation structure is a structure generated by separating a homogeneous phase into two phases by spinodal decomposition. In the present invention, the two phases in a phase separated state are separated into one phase like a sea-island structure. Refers to a state in which is mixed and mixed without being isolated. FIG. 3 shows a two-dimensional schematic diagram of the modulation structure.

When the charge transporting phase and the electrically inactive phase have a sea-island structure in which the charge transporting portion is an island and the electrically inactive portion is the sea, the charge transporting portion becomes an island and exists independently. In addition, charge transport is hindered, which tends to cause an increase in residual potential, a decrease in photosensitivity, a decrease in charge transport speed, and the like, making control difficult. On the other hand, the electrically inactive part is an island,
When the charge transport portion becomes the sea, the charge transport path is secured, but it is difficult to form a spatial trap for temporarily stopping the charge, and the S-shaped property is deteriorated.

The spatial trap is a portion where the charge transport portion is convex in the direction in which the charge is to be transported, and acts as a trap only when an electric field is applied. The presence of many of these spatial traps is key to creating an S-shaped PIDC. In the case of a modulation structure comprising a charge transport portion and an electrically inactive portion, the charge transport portion is in a continuous phase without being isolated, so that the charge transport can be carried out without breaking the charge transport path. In addition, since the charge transport portion and the electrically inactive portion intersect in a complicated shape, there are many portions that are convex in the direction in which the charge should be transported, which can act as a spatial trap. .

As described above, in the case of the modulation structure including the charge transporting portion and the electrically inactive portion, the securing of the charge transporting path and the securing of the spatial trap are compatible, so that the residual potential increases and the photosensitivity decreases. An electrophotographic photoreceptor having a good S-shaped property without any obstacles caused by the separation of the charge transport path such as a decrease in the charge transport rate and a decrease in the charge transport speed.

According to the present invention, since the charge transport layer is in a phase-separated state composed of a charge transporting phase and an electrically inactive phase and has a modulation structure, the charge transporting path is not divided, and The phase separation state is preferably formed by a block copolymer or a graft copolymer comprising a charge transporting block and an insulating block.

Here, it is known that the scale of phase separation in the block copolymer and the graft copolymer is generally the same dimension as the average length of each block, and is substantially proportional to the molecular weight. Therefore, not only can the size of the phase be controlled by adjusting the molecular weight, but the size of this phase does not greatly vary depending on the manufacturing conditions,
A photoconductor having stable characteristics can be provided.

It is to be noted that the transport energy level is far from the transport energy level of the main transport charge, and that the transport charge is substantially injected at the ordinary electric field strength. Rather, it is effectively in an electrically insulating state for the main charge.

Further, the charge transport layer is in a phase-separated state in which the charge transport layer has a modulation structure composed of a charge transport phase and an electrically inactive phase, and a block copolymer or graft copolymer comprising a charge transport block and an insulating block. By providing a charge transporting layer having different properties between the heterogeneous charge transporting layer made of a polymer and a uniform charge transporting layer containing a charge transporting matrix, charge transport can be smoothed and the charge transporting speed can be increased. At the same time, effects such as reduction of the residual potential can be achieved.

Further, a layer comprising a block copolymer or a graft copolymer comprising a charge transporting block and an insulating block in a phase-separated state having a modulation structure comprising a charge transporting phase and an electrically inactive phase. a layer made of a charge transporting matrix and is by being laminated in this order, since the layer made of the charge transporting matrix becomes the outermost layer, wear resistance, ozone resistance, excellent like resistance NO _X resistant An electrophotographic photoreceptor can be provided.

Further, by using the above-mentioned electrophotographic photoreceptor, it is possible to provide an electrophotographic apparatus having exposure means for performing exposure based on a digitally processed image signal, which has good and stable image quality.

The S-shaped scale of the photo-induced potential decay curve includes:
For example, the exposure amount required to attenuate the charged potential by 50%
E_50%And the exposure E required to attenuate by 10%_Ten%With
Ratio E _50%/ E_Ten%Can be used. Ideal J-shape
If the potential decay is proportional to the amount of exposure in
_50%/ E_Ten%The value is 5. With a general J-shaped photoreceptor
Increases the electric charge generation efficiency and / or
Has a reduced charge transport ability and E _50%/ E_Ten%Is more than 5
Is shown. On the other hand, S-shaped ultimate, up to a certain exposure
No potential decay at all, the residual potential level at once with that exposure
In a step-like photoinduced potential decay curve in which the potential decays to
_50%/ E_Ten%The value is 1. Therefore, the S-shape is E
_50%/ E_Ten%Defined as having a value in the range of 1-5
Is done.

A block copolymer or a graft copolymer consisting of a charge transporting block and an insulating block is in a phase-separated state having a modulation structure consisting of a charge transporting phase and an electrically inactive phase. Is abbreviated as “heterogeneous charge transporting layer”, and a layer containing the charge transporting matrix is abbreviated as “uniform charge transporting layer”.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each layer constituting the electrophotographic photosensitive member of the present invention will be described in more detail.

FIGS. 4 and 5 are schematic views showing a cross section of the electrophotographic photosensitive member of the present invention. In FIG. 4, a charge generation layer 2 for generating photocharges is provided on a conductive support 1, and a non-uniform charge transport layer 3 is provided thereon. In FIG. 5, a charge generation layer 2 for generating photocharges is provided on a conductive support 1, and a non-uniform charge transport layer 3 for forming an S-shape is provided thereon. A uniform charge transport layer 4 for charge transport is provided, and a charge transport layer 5 is formed by the non-uniform charge transport layer 3 and the uniform charge transport layer 4. 6 and 7, an undercoat layer 6 is further provided between the conductive support 3 and the charge generation layer 1.

FIGS. 8 to 11 are schematic views showing a cross section of an electrophotographic photosensitive member according to another embodiment of the present invention. In FIG. 8, a non-uniform charge transport layer 3 is provided on a conductive support 1, and a charge generation layer 2 is provided thereon. In FIG. 9, a uniform charge transport layer 4 is provided on a conductive support 1, and a non-uniform charge transport layer 3 is provided thereon.
3, the charge transport layer 5 is formed, and the charge generation layer 2 is further provided thereon. 10 and 11, the conductive support 1 and the uniform charge transport layer 4 are further illustrated.
An undercoat layer 6 is provided between the two.

These electrophotographic photoreceptors can further include a protective layer and / or a diffuse reflection layer, if desired.

As described above, if the moving distance until the charge generated in the charge generation layer is temporarily stopped in the non-uniform charge transport layer is sufficiently small with respect to the total thickness of the photosensitive layer, the potential decay during that time is small. It becomes negligible, and becomes a more ideal S-shaped photoreceptor. In other words, the closer the charge generation layer and the non-uniform charge transport layer for forming the S-shape, the better the S-shape. However, an intermediate layer may be provided between the charge generation layer and the non-uniform charge transport layer for the purpose of injecting charges and assisting the generation of charges. It is also possible to insert a uniform charge transport layer between the charge generation layer and the non-uniform charge transport layer in order to obtain the desired imperfect S-shape.

The surface layer is also the charge retention time of the charge in addition to the photoelectric functions, ozone generated from the charging member and the like, resistance to discharge products such as NO _X, and, paper, etc. resistance to, such as by abrasion cleaning member Are required at the same time. The laminated type having only the charge generation layer and the charge transport layer having a non-uniform structure as shown in FIG. 4 has the simplest structure, but the non-uniform charge transport layer has the above-described durability function, charge transport property and S Character conversion functions are required, and it is difficult at present to satisfy all of these functions, and the range of material selection becomes narrow. In the case of an electrophotographic photoreceptor having a structure as shown in FIGS. 5 and 6, since the uniform charge transport layer is on the surface side, the S-shape is caused by the non-uniform charge transport layer inside the photosensitive layer. The above function required for the layer can be designed separately from the charge generation and the S-shape, thereby increasing the degree of freedom in design.

These electrophotographic photoreceptors can further include a protective layer and / or a diffuse reflection layer, if desired.

The conductive support may be opaque or substantially transparent, and may be made of metals such as aluminum, nickel, chromium and stainless steel, and aluminum, titanium, nickel, chromium and stainless steel. , Gold, vanadium, tin oxide, indium oxide, IT
Plastic film, glass, etc. provided with a thin film such as O
Alternatively, paper, plastic film, glass and the like coated or impregnated with a conductivity-imparting agent may be used. These conductive supports are used in an appropriate shape such as a drum shape, a sheet shape, and a plate shape, but are not limited thereto. Further, if necessary, various treatments can be performed on the surface of the conductive support within a range that does not affect the image quality. For example, surface oxidation treatment and chemical treatment,
Further, coloring treatment or the like, or irregular reflection treatment such as graining can be performed.

One or more subbing layers may be provided between the conductive support and the photoconductive layer. The undercoat layer acts as an adhesive layer that prevents the injection of charges from the conductive support into the photosensitive layer when the photosensitive layer is charged, and that integrally holds the photosensitive layer on the conductive support. Or, in some cases, an antireflection effect of light from the conductive support.

As the undercoat layer, known ones can be used. For example, polyethylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, Polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride
Vinyl acetate copolymer, polyvinyl alcohol resin, water-soluble polyester resin, alcohol-soluble nylon resin,
Nitrocellulose, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, polyacrylic acid, resins such as polyacrylamide and copolymers thereof, or a zirconium alkoxide compound,
Curable metal organic compounds such as a titanium alkoxide compound and a silane coupling agent can be used alone or in combination of two or more. Further, a material capable of transporting only charges having the same polarity as the charged polarity can be used.

The thickness of the undercoat layer is from 0.01 to 10
μm is appropriate, and preferably in the range of 0.05 to 5 μm. As a coating method, a blade coating method,
Wire bar coating method, spray coating method,
Conventional methods such as a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method can be used.

As the charge generating material in the charge generating layer of the electrophotographic photoreceptor of the present invention, known materials used as a charge generating layer in a conventional J-shaped laminated photoreceptor can be used. For example, amorphous selenium, selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and alloys, zinc oxide, titanium oxide, α-Si, α-
Organic pigments and dyes such as inorganic photoconductive materials such as SiC, phthalocyanine-based, squarium-based, anthrone-based, perylene-based, azo-based, anthraquinone-based, pyrene-based, pyrylium salts, and thiapyrylium salts can be used.
It is not limited to these. These organic pigments and dyes can be used alone or in combination of two or more.

The phthalocyanine-based compound is used as a light source in a digital electrophotographic apparatus and is used as a light source for LEDs and laser diodes, which are currently used as light sources.
Since it has excellent photosensitivity at 0 to 850 nm, it is particularly preferable as the charge generation material of the present invention. Specifically, it is a metal-free phthalocyanine, a metal phthalocyanine, and a dimer thereof. As the central metal of the metal phthalocyanine, Cu, Ni, Zn, Co, Fe, V, Si, Al,
Examples thereof include Sn, Ge, Ti, In, Ga, Mg, and Pb, and oxides, hydroxides, halides, alkylates, and alkoxylates of these central metals can also be used.
Specific examples include metal-free phthalocyanine, titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, 1,2-di (oxogallium phthalocyaninyl) ethane, vanadyl phthalocyanine, chloroindium phthalocyanine, dichlorotin phthalocyanine, copper phthalocyanine, and the like. be able to. Further, those having an arbitrary substituent in these phthalocyanine rings can also be used. Further, those in which an arbitrary carbon atom in these phthalocyanine rings is substituted with a nitrogen atom are also effective. As the form of these phthalocyanine-based compounds, it is possible to use almorphous or all known polymorphs. These phthalocyanine compounds can be used alone or as a mixture of two or more.

Among these phthalocyanine compounds,
Titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, 1,2-di (oxogallium phthalocyaninyl) ethane, metal-free phthalocyanine, vanadyl phthalocyanine, and dichlorotin phthalocyanine have particularly excellent photosensitivity, Particularly preferred as a generating material. Among these, a particularly preferred crystal system is X-type for metal-free phthalocyanine and α-type for vanadyl phthalocyanine. In the titanyl phthalocyanine crystal, CuKα
Angle of X-ray diffraction spectrum (2θ
± 0.2 °) is at least 9.2 °, 13.1 °, 2
Those with strong diffraction peaks at 0.7 °, 26.2 °, and 27.1 °, at least 7.6 °, 12.3 °,
Those with strong diffraction peaks at 16.3 °, 25.3 ° and 28.7 ° and at least 9.5 °, 1
Hydrates having strong diffraction peaks at 1.7 °, 15.0 °, 23.5 °, and 27.3 ° can be mentioned. In a chlorogallium phthalocyanine crystal, C
X-ray diffraction spectrum with uKα as a source having strong diffraction peaks at least at 13.4 ° and 27.0 ° at Bragg angles (2θ ± 0.2 °), and at least 7.4 °, 16.6 °, 25.5 ° and 2
Those having a strong diffraction peak at 8.3 ° can be mentioned. In the hydroxygallium phthalocyanine crystal, the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using CuKα as a source is at least 7.5 °,
9.9 °, 12.5 °, 16.3 °, 18.6 °, 2
Those having strong diffraction peaks at 5.1 ° and 28.3 ° can be mentioned. In the 1,2-di (oxogallium phthalocyaninyl) ethane crystal, the Bragg angle (2θ ±) of the X-ray diffraction spectrum using CuKα as a radiation source.
0.2 °) is at least 6.9 °, 13.0 °, 1
Those having strong diffraction peaks at 5.9 °, 25.6 ° and 26.1 ° can be mentioned. In the dichlorotin phthalocyanine crystal, the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using CuKα as a source is
Those with strong diffraction peaks at least at 8.3 °, 13.7 ° and 28.3 °, at least 8.5 °, 1
Those with strong diffraction peaks at 1.2 °, 14.5 ° and 27.2 °, and at least 9.2 °, 12.12.
2 °, 13.4 °, 14.6 °, 17.0 ° and 2
Those having a strong diffraction peak at 5.3 ° can be given.

Most phthalocyanine-based compounds have the property of a p-type semiconductor in which holes are the main transport charge, whereas dichlorotin phthalocyanine is an n-type semiconductor in which the electron is the main transport charge. have. Therefore, an S-shaped photoreceptor containing dichlorotin phthalocyanine as a charge generation material and sequentially laminating a charge generation layer and a charge transport layer on a conductive substrate has a high sensitivity and Positive charge injection from a conductive base material is suppressed, and good electrophotographic characteristics are obtained with low dark decay and high chargeability.

The charge generation layer is formed by forming the charge generation material on a conductive support by vacuum evaporation or by dispersing or dissolving the charge generation material in a binder resin. And dried.

The binder resin used for the charge generation layer is a polyvinyl butyral resin, a polyvinyl formal resin, a partially modified polyvinyl acetal resin, a polycarbonate resin, a polyester resin, an acrylic resin, a polyvinyl chloride resin, a polystyrene resin, a polyvinyl acetate. Examples include, but are not limited to, resins, vinyl chloride-vinyl acetate copolymers, silicone resins, phenolic resins, poly-N-vinylcarbazole resins, and the like. These binder resins can be block, random or alternating copolymers. These binder resins can be used alone or in combination of two or more.

The mixing ratio (volume ratio) of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10. More preferably, it is set in the range of 3: 1 to 1: 3. When the compounding ratio of the charge generation material to the binder resin is larger than the above range, dark decay is increased and mechanical properties are deteriorated. If the amount is less than the above range, problems such as a decrease in photosensitivity and an increase in residual potential occur. In general, the thickness of the charge generation layer used in the present invention is suitably from 0.05 to 5 μm, and preferably from 0.1 to 2.0 μm. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used.

The heterogeneous charge transport layer is in a phase-separated state having a modulation structure composed of a charge transporting phase and an electrically inactive phase, and is a block copolymer or graft comprising a charge transporting block and an insulating block. In the layer formed from the copolymer, the charge transporting phase is formed by the charge transporting block, and the electrically inactive phase is formed by the insulating block.

As a block copolymer or a graft copolymer comprising a charge transport block and an insulating block as a material for forming a heterogeneous charge transport layer having a modulation structure, there are known charge transport blocks and insulating blocks. Block copolymers or graft copolymers can be used.

Examples of usable block or graft copolymers include, for example, multiblock copolymers produced by copolymerizing vinylcarbazole and dodecyl methacrylate described in US Pat. No. 3,994,994. Can be Other US Pat. No. 4,618,5
No. 51, No. 4,806,443, No. 4,818,65
Nos. 0, 4,935,487, and 4,956,4
No. 40, block copolymers containing low molecular weight polysiloxanes, aliphatic and aromatic polyesters and polyurethane units and produced by condensation can also be used.

Further, a copolymer in which the charge-transporting block contains a triarylamine structure as a repeating unit is preferable because of having a high charge-transporting ability. (1)
Alternatively, it is particularly preferable that at least one of the structures represented by (2) is contained as a repeating unit.

[0048]

Embedded image

(Wherein, Ar ₁ and Ar ₂ each independently represent a substituted or unsubstituted aryl group, and X ₁ represents a divalent hydrocarbon group having an aromatic ring structure or a heteroatom-containing hydrocarbon group. , X ₂ and X ₃ each independently represent a substituted or unsubstituted arylene group; L ₁ represents a divalent hydrocarbon group or a heteroatom-containing hydrocarbon group which may have a branched or cyclic structure; And n each represent an integer selected from 0 or 1.)

[0050]

Embedded image

(Wherein, Ar ₃ and Ar ₄ each independently represent a substituted or unsubstituted aryl group, and L ₂ represents a trivalent hydrocarbon group having an aromatic ring structure or a hetero atom-containing hydrocarbon group. In the general formula (1), Ar ₁ and Ar ₂ are each independently selected from a substituted or unsubstituted aryl group, and specific examples of the aryl group include a phenyl group, a biphenyl group,
Examples include a naphthyl group and a pyrenyl group. Examples of the substituent include a methyl group, an ethyl group, a methoxy group, and a halogen atom. X ₁ is selected from a divalent hydrocarbon group having an aromatic ring structure or a hetero atom-containing hydrocarbon group. Specific examples include a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group, a methylenediphenyl group, a cyclohexylidenediphenyl group, an oxydiphenyl group, a thiodiphenyl group, and the like, and methyl-substituted, ethyl-substituted, and methoxy-substituted thereof. Or a halogen-substituted compound. Among them, a substituted or unsubstituted biphenylene group is particularly preferred in view of charge transportability.

X ₂ and X ₃ are each independently selected from a substituted or unsubstituted arylene group. Specifically, phenylene group, biphenylene group, terphenylene group, naphthylene group and the like, and methyl-substituted products thereof, ethyl Substitutes, methoxy substitutes, halogen substitutes and the like can be mentioned.

L ₁ is selected from a divalent hydrocarbon group or a heteroatom-containing hydrocarbon group which may have a branched or cyclic structure, and is optional as long as it exhibits at least one of the above-mentioned preferable characteristics. Those containing a bonding group selected from an ether bond, an ester bond, a carbonate bond, a siloxane bond and the like, and having 20 or less carbon atoms are preferable. Specific examples include the following.

[0054]

Embedded image

In the general formula (2), Ar ₃ and A
r ₄ is independently selected from a substituted or unsubstituted aryl group, and specific examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, and a pyrenyl group. In addition, examples of the substituent include an alkyl group or an alkoxy group having 1 to 12 carbon atoms, a diarylamino group, and a halogen atom.

L ₂ is selected from a trivalent hydrocarbon group having an aromatic ring structure or a heteroatom-containing hydrocarbon group, and is arbitrary as long as it exhibits at least one of the preferable characteristics described above. The following are preferred. Specific examples include the following.

[0057]

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The insulating block forming the copolymer of the present invention may be of any type. Specific examples of the insulating block include polyvinyl acetal, polyalkyl methacrylate, polyalkyl acrylate, polyvinyl chloride, polystyrene, polyvinyl acetate, polyalkyl vinyl ether, polycarbonate, polyester,
Examples include polysiloxanes and the like, and blocks, grafts, random or alternating copolymers thereof. However, mechanical strength, flexibility, visible and infrared light transmission,
From the viewpoints of chemical stability, insulating properties, and the like, those composed of a polymer of a vinyl monomer are preferable, and those obtained by polymerizing at least one vinyl monomer represented by the following general formula (3) are particularly preferable.

[0059]

Embedded image

In the general formula (3), R _{1 to} R ₃ are each independently selected from a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl or aryl group. Specific examples of the substituted or unsubstituted alkyl group or aryl group include a methyl group, an ethyl group, a methoxy group, a chloromethyl group, a phenyl group, a tolyl group and the like.

R ₄ is a substituted or unsubstituted alkyl group,
It is selected from an aryl group, an alkoxy group, an acyl group, an acyloxy group, or an alkoxycarbonyl group. The alkyl group, alkoxy group, acyl group, acyloxy group, and alkoxycarbonyl group preferably have 1 to 18 carbon atoms, and examples of the aryl group include a phenyl group, a naphthyl group, and pyrenyl. Examples of the substituent include a halogen atom, a phenyl group, a hydroxy group, an amino group, an isocyanate group, an epoxy group, and an alkoxysilyl group.

In the copolymer of the present invention, specific examples of the structural formula represented by the above general formula (1), which is contained as a repeating unit in the charge transporting block, are shown in Tables 1 and 2 below. Specific examples of the structural formula represented by (2) are shown in Table 3 below, and specific examples of the structural formula represented by the above general formula (3), which is contained as a repeating unit in the insulating block, are shown in the following Table. 4, the present invention is not limited to these.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

The resistance value of the insulating block in the copolymer of the present invention is preferably 10 ¹³ Ωcm or more, and especially 1
0 ¹⁴ Ωcm is preferred. When an insulating block having a volume resistivity lower than this range is used, the electrical insulation of an electrically inactive phase formed by the block tends to be impaired, and the S-shaped property tends to be lost. It is difficult to directly measure the electric resistivity in the copolymer, and the electric resistivity of a polymer having the same structure as the insulating block can be used instead.

As long as the copolymer of the present invention is a block copolymer or a graft copolymer, its constituent blocks may be connected in any manner. That is, when the charge transporting block is represented by A and the insulating block is represented by B, AB
Type, ABA type, BAB type, (AB) _n type, (AB) _n A
And B (AB) _n- type block copolymers, graft copolymers having a charge transporting block as a main chain and an insulating block as a side chain, an insulating block as a main chain, and a charge transporting block as a side chain Or a block-graft copolymer obtained by grafting A and / or B to the side chain of a block copolymer such as ABA. Both the charge transporting block and the insulating block may include two or more types of structural units. Further, a copolymer and a charge transporting high molecular compound or an insulating high molecular compound can be used together. In this case, a polymer compound containing a structural unit of a copolymer is preferable.

In order to form a modulation structure suitable as a heterogeneous charge transport layer by using a copolymer having the charge transport block and the insulating block, it is necessary to separate a homogeneous phase into two phases. . As a method of separating into two phases, in the case of a mixture in which both blocks have a property of separating from a uniform phase into two phases by heating, a method of heating and then cooling the film of the uniform phase to form a modulation structure is adopted. It is possible. In addition, both are dissolved in a common solvent to form a uniform phase, and in the process of evaporating and increasing the concentration of the solvent, a method of separating into two phases, dissolving both in a mixed solvent to form a uniform phase,
The modulation structure can also be formed by a method of separating into two phases while the solvent evaporates and the solvent composition changes.

The volume ratio between the charge transporting block and the insulating block is arbitrarily set in the range of 9/1 to 1/9.
The range of 8/2 to 2/8 is preferred. More preferably, 7
/ 3 to 3/7. Even if the volume ratio of the charge transporting block is larger or smaller than the above range, it becomes difficult to form a modulation structure. However, the volume ratio at which the modulation structure can be easily formed is determined depending on each material configuration, film forming conditions, and the like.

The phase pitch (indicated by, for example, width a in FIG. 3) of the charge transporting portion is preferably 0.001 to 1 μm.
It is more preferably in the range of 0.005 to 0.5 μm, and particularly preferably in the range of 0.01 to 0.2 μm. When the pitch of the charge transporting phase is larger than the above range, the formation of spatial traps required for forming the S-shape within the preferable thickness range is stochastically reduced, and the S-shape is lost. On the other hand, when the pitch of the charge transporting phase is smaller than the above range, the spatial trap becomes too shallow and the S-character tends to be lost.

In the copolymer, the phase pitch can be controlled by the molecular weight of each block. As the molecular weight of the block increases, the pitch of the phase also increases, and as the molecular weight of the block decreases, the pitch of the phase decreases. The molecular weight of each block is suitably in the range of 2,000 to 1,000,000. If the molecular weight of each block is less than 2,000, the phase pitch becomes too small, and if it is 1,000,000 or more, the phase pitch becomes too large. Here, the molecular weight refers to a volume average molecular weight.

The phase pitch can also be adjusted by appropriately selecting a solvent, using a mixed solvent, adjusting the evaporation rate of the solvent, and cooling rate.

Here, as a preferable combination of the substances constituting the charge transporting block and the insulating block, when the solubility parameter of the charge transporting polymer compound and the insulating polymer compound having the same constitution as each block is measured, To the extent that there is a common solvent to effect the separation,
It is preferable that they are separated.

The thickness of the heterogeneous charge transport layer used in the present invention is suitably 5 to 100 μm, preferably 10 to 100 μm, when the charge transport layer is formed of only the heterogeneous charge transport layer without being combined with the uniform charge transport layer. It is set in the range of ５０50 μm. When the charge transport layer is formed by combining the heterogeneous charge transport layer with the uniform charge transport layer, the charge transport layer may have a thickness of 0.1 to 50 μm.
Is suitably set, preferably in the range of 0.2 to 20 μm, more preferably in the range of 0.5 to 10 μm. If the thickness is smaller than the above range, the S-shaped property tends to be lost. The upper limit of the film thickness is limited by the charge transporting ability of the S-shaped charge transporting layer to be used, and the response speed, the residual potential, and the like are set within allowable ranges.

Further, by adding a compound capable of transporting only a charge having a polarity opposite to that of the main transport charge to the heterogeneous charge transport layer, effects such as a decrease in residual potential and an improvement in repetition stability can be obtained. It is preferable that they are contained in a phase made of an insulating polymer compound.

The method of applying the non-uniform charge transporting layer includes blade coating, wire bar coating, and the like.
Conventional methods such as spray coating, dip coating, bead coating, air knife coating, and curtain coating can be used.

As the uniform charge transporting layer, that is, the layer containing the charge transporting matrix, a known charge transporting layer used in a conventional J-shaped laminated photoreceptor can be used. For example, benzidine compounds, amine compounds, hydrazone compounds, stilbene compounds, hole transporting low molecular weight compounds such as carbazole compounds or fluorenone compounds, malononitrile compounds, electron transporting low molecular weight compounds such as diphenoquinone compounds. ,
Alone or in combination of two or more, polycarbonate,
A solid solution film in which molecules are uniformly dispersed in an insulating resin such as polyarylate, polyester, polysulfone, and polymethyl methacrylate, or a polymer compound having a charge transporting ability by itself can be used. Further, an inorganic substance having a charge transporting ability, such as selenium, amorphous silicon, or amorphous silicon carbide, can also be used.
Examples of the charge-transporting polymer compound include a polymer compound having a charge-transporting group such as polyvinylcarbazole in the side chain, and a group having a charge-transporting property as disclosed in JP-A-5-232727. And a polysilane having a main chain of

The uniform charge transport layer in the present invention includes
In particular, it is preferable to use a charge transporting polymer compound in production. That is, when the heterogeneous charge transport layer and the uniform charge transport layer are formed into a multilayer film, when the charge transport low molecular compound is used for the uniform charge transport layer, the charge transport low molecular compound is mixed into the heterogeneous charge transport layer. In other words, the insulating property of the electrically inactive phase of the heterogeneous charge transport layer against the main charge is reduced, so that the S-shaped property is impaired, or mixed molecules become charge traps, increasing the residual potential, decreasing the transport ability, and reducing light Failures such as a decrease in sensitivity occur. This problem is particularly noticeable when each layer is formed by a wet coating method. Of course, these problems can be avoided by selecting a solvent that does not easily dissolve and swell the lower layer as a coating solvent for the upper layer, or by selecting an insulating block that is incompatible with the charge transporting low molecular weight compound. However, it is known that polymers are rarely compatible with each other, and it is common to cause phase separation, and a charge-transporting polymer compound is used as a uniform charge-transporting layer. If there is, the phase separation without compatibilizing with the electrically inactive phase of the heterogeneous charge transporting layer, the problem of the above-mentioned mixing hardly occurs,
This has the advantage that restrictions in selecting materials and manufacturing methods are eliminated.

For the above reason, when a uniform charge transporting layer composed of a charge transporting polymer is used, it is desirable that the layer does not contain 5% or more of a charge transporting compound having a molecular weight of 1,000 or less.

Further, as the charge transporting polymer compound of the uniform charge transporting layer, in the case of a charge transporting resin containing at least one of the structures represented by the general formula (1) or (2) as a repeating unit, Has high charge transport ability,
It is particularly preferable because it has excellent mechanical properties.

In the uniform charge transporting layer, an electrically inactive region may be present as long as the surroundings are surrounded by the charge transporting matrix. For example, insulating particles and the like can be included in the charge transporting matrix layer for the purpose of reducing surface friction, abrasion, and surface deposits. Further, the uniform charge transporting layer may contain charge transporting fine particles or the like in order to improve the transportability.

As a method for applying the uniform charge transporting layer, ordinary methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method and a curtain coating method are used. be able to. In addition, those capable of vapor phase film formation can be directly formed by a vacuum evaporation method or the like.

The uniform charge transport layer used in the present invention has a thickness of 1
１００100 μm, preferably 5-50 μm.

In the present invention, the total thickness of the entire charge transporting layer is generally suitably from 5 to 100 μm, preferably from 10 to 50 μm.

When the charge transporting layer is present between the charge generating layer and the exposure light source, it is desirable that the charge transporting layer is practically transparent to light having an exposure wavelength in order to prevent a decrease in effective photosensitivity. Preferably, the transmittance of light used for exposure in the charge transport layer is 50% or more. It is more preferably at least 70%, further preferably at least 90%. However, if use at low sensitivity is desired, a charge transport layer that effectively absorbs light at the exposure wavelength can be used to adjust the effective light sensitivity. A protective layer may be further provided on the photoconductive layer including the charge generation layer and the charge transport layer, if necessary. This protective layer forms the photoconductive layer from chemical stress such as ozone and oxidizing gas generated from the charging member and ultraviolet light, or mechanical stress caused by contact with a developer, paper, a cleaning member, and the like. It is effective to protect and improve the substantial life of the photoconductive layer. In particular, the effect is remarkable in a layer configuration using a thin charge generation layer as an upper layer.

The protective layer is formed by including a conductive material in a suitable binder resin. Examples of the conductive material include metallocene compounds such as dimethylferrocene, antimony oxide,
Materials such as metal oxides such as tin oxide, titanium oxide, indium oxide, and ITO can be used, but not limited thereto. As the binder resin, polyamide, polyurethane, polyester, polycarbonate,
Polystyrene, polyacrylamide, silicone resin,
Known resins such as a melamine resin, a phenol resin, and an epoxy resin can be used. Also, a conductive inorganic film such as amorphous carbon can be used as the protective layer.

The electric resistance of the protective layer is 10 ⁹ to 10 ¹⁴ Ω · c.
The range of m is preferred. When the electric resistance is higher than this range, the residual potential increases. On the other hand, when the electric resistance is lower than this range, the charge leakage in the creeping direction cannot be ignored, and the resolution decreases.

The thickness of the protective layer is suitably from 0.5 to 20 μm, preferably from 1 to 10 μm.
When a protective layer is provided, a blocking layer for preventing leakage of electric charge from the protective layer to the photosensitive layer can be provided between the photosensitive layer and the protective layer, if necessary. As the blocking layer, a known layer can be used as in the case of the protective layer.

In the electrophotographic photoreceptor of the present invention, ozone or oxidizing gas generated in the electrophotographic apparatus, or
An antioxidant, a light stabilizer, a heat stabilizer and the like can be added to each layer or the uppermost layer for the purpose of preventing the photoconductor from being deteriorated by light and heat.

As the antioxidant, known ones can be used. For example, hindered phenol, hindered amine, paraphenylenediamine, hydroquinone,
Spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, organic phosphorus compounds and the like can be mentioned.

As the light stabilizer, known ones can be used. For example, derivatives such as benzophenone, benzotriazole, dithiocarbamate, tetramethylpiperidine, and the like can deactivate the photoexcited state by energy transfer or charge transfer. Examples thereof include an electron-withdrawing compound or an electron-donating compound.

Further, reduction of surface wear, improvement of transferability,
Insulating particles such as a fluororesin may be dispersed in the outermost surface layer for the purpose of improving the cleaning property and the like.

As the electrophotographic apparatus equipped with the electrophotographic photosensitive member of the present invention, any apparatus may be used as long as it employs an electrophotographic method. In particular, an electrophotographic apparatus which performs exposure based on a digitally processed image signal is used. Is preferred. An electrophotographic apparatus that performs exposure based on a digitally processed image signal is an electrophotographic apparatus that uses a light source such as a laser or an LED to perform binary or pulse width modulation or intensity modulation and expose with multi-valued light. There are, for example, an LED printer, a laser printer, a laser exposure type digital copier and the like. E _50% of S-shaped photoreceptor
The / E _10% value is a value of 5 or less. In order to exhibit preferable digital characteristics, the value of E _50% / E _10% is preferably less than 3. More preferably, the value is less than 2.

Further, for the purpose of initializing the photoreceptor after development or stabilizing the electrophotographic characteristics, a light source for exposure can be used in addition to the light source for image formation. The region may be one that is absorbed or not absorbed by the heterogeneous charge transport layer,
It is preferable that light reaches at least the charge generation layer.

[0096]

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples, and those skilled in the art can modify the following examples based on known knowledge of electrophotographic technology.

Synthesis Example 1: Reactive polymerization initiator 4,4'-
Synthesis of azobis (4-cyanovaleric chloride) 140 ml of thionyl chloride was ice-cooled, and 48 g of 4,4'-azobis (4-cyanovaleric acid) was gradually added. 30 ° C
For 6 hours, and excess thionyl chloride was distilled off under reduced pressure. The residue was recrystallized from chloroform to give 22 g of 4,
4′-Azobis (4-cyanovaleric chloride) crystals were obtained.

Synthetic Example 2: Having azo-type polymerization initiator at both ends
Of 3,3′-dimethyl-N, N′-bis (p, m-dimethylphenyl) -N, N′-bis [4- (2-methoxycarbonylethyl) phenyl]-[ 1,1′-biphenyl] -4,4′-diamine 100 g, ethylene glycol 200 g and tetrabutoxytitanium 5 g,
The mixture was heated and refluxed for 3 hours under a nitrogen stream. 3,3′-dimethyl-N, N′-bis (p, m-dimethylphenyl) -N,
After confirming that N'-bis [4- (2-methoxycarbonylethyl) phenyl]-[1,1'-biphenyl] -4,4'-diamine was consumed, 0.5 mmHg was used.
To 230 ° C while distilling off ethylene glycol
And the reaction was continued for another 7 hours. Thereafter, the mixture is cooled to room temperature, methylene chloride is added to dissolve the insoluble matter, and the precipitate is reprecipitated from acetone to give 90 g of a charge transporting polymer having a hydroxy group at both terminals represented by the following structural formula (1). Obtained. The weight average molecular weight of the obtained polymer was 7.2 × 10 ⁴ .

43 g of the charge transporting polymer having hydroxy groups at both ends and 0.5 g of triethylamine were dissolved in 120 ml of dichloromethane and cooled to 0 ° C. Here, the 4,4′-azobis (4-
5.6 g of cyanovaleric chloride) in dichloromethane 20
The solution dissolved in ml was dropped. After reacting at room temperature for 1 hour, the mixture was heated to 30 ° C., and further reacted for 4 hours. The solvent was distilled off from this, and it was dissolved by adding tetrahydrofuran, added dropwise to methanol, stirred for 1 hour, and filtered. This reprecipitation operation was repeated twice more. The residue was dried to obtain 41 g of a charge transporting polymer having an azo type polymerization initiator at both terminals.

Synthesis Example 3: Compound represented by the following structural formula (2)
Synthesis of lock copolymer 6 g of charge-transporting polymer having an azo-type polymerization initiator at a terminal obtained in Synthesis Example 2 and 6 g of n-dodecyl methacrylate
Was dissolved in 120 ml of toluene and replaced with nitrogen.
Heated at ° C for 65 hours. The solvent was removed therefrom, tetrahydrofuran was added, the solution was added dropwise to methanol, and the mixture was stirred for 1 hour and filtered. The obtained solid is a mixture of the target block copolymer and poly (n-dodecyl methacrylate) homopolymer, and is obtained by the following purification method utilizing the difference in solubility. Was removed to obtain the desired block copolymer. That is, the charge transporting polymer of Synthesis Example 2 is insoluble, and the mixture is sufficiently washed with a solvent n-hexane in which poly (n-dodecyl methacrylate) is easily soluble, so that the desired block copolymer is obtained. 6 g of a polymer was obtained. From the integral ratio of the peaks corresponding to the protons specific to both blocks in the 1H-NMR spectrum of the obtained block copolymer, the volume composition ratio of the charge transporting block and the insulating block composed of poly (n-dodecyl methacrylate) is approximately 55:45 is calculated. In addition, poly (n-) having the same structure as the insulating block of the block copolymer of the synthesis example.
Dodecyl methacrylate) has a volume resistivity of 10 ¹⁴ Ω · c
m or more.

[0101]

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Synthesis Example 4: Compound represented by the following structural formula (1)
Synthesis of lock copolymer 20 g of the charge-transporting polymer having azo-type polymerization initiation groups at both ends obtained in Synthesis Example 2 and 35 g of tert-butyl methacrylate were dissolved in 400 ml of toluene, and after displacing with nitrogen, the solution was heated at 65 ° C. Heated for 100 hours. This was dropped into hexane, stirred for 1 hour, and then filtered off. The solvent was removed therefrom, tetrahydrofuran was added, the solution was added dropwise to methanol, and the mixture was stirred for 1 hour and filtered. Further, the reprecipitation operation with toluene / hexane was repeated twice. The residue was dried under reduced pressure to obtain 30 g of a block copolymer represented by the following structural formula (1).

[0103]

Embedded image

From the 1H-NMR spectrum of the obtained copolymer, the volume composition ratio of the charge transporting block and the insulating block was calculated to be approximately 52/48 from the integrated intensity ratio of protons assigned to each block. The volume resistivity of poly (tert-butyl methacrylate) having the same structure as the insulating block of the block copolymer of the present example is 1
0 ¹⁴ Ω · cm or more.

Synthesis Example 5: Compound represented by the following structural formula (3)
Synthesis of reblock copolymer N, N'-bis (p, m-dimethylphenyl) -N,
N′-bis [p- (2-methoxycarbonylethyl) phenyl]-[3,3′-dimethyl-1,1′-biphenyl] -4,4′-diamine is converted to N, N-bis (p, m- A charge-transporting polymer having an azo-type polymerization initiator at both ends was prepared in the same manner as in Synthesis Example 2 except that dimethylphenyl) -N- [p- (m, m'-bismethoxycarbonylethyl) phenyl] amine was used. The coalescence was synthesized. Further, a triblock copolymer represented by the following structural formula (3) was synthesized in the same manner as in Synthesis Example 3 except that a charge transporting polymer having an azo type polymerization initiator at both ends was used.

The weight average molecular weight of the charge transporting prepolymer having a triarylamine structure was 5.2 × 10 ³ . From the integrated intensity ratio of protons belonging to each block of the 1H-NMR spectrum of the obtained copolymer, the volume composition ratio of the charge transporting block and the insulating block was about 5
9/41 was calculated.

[0107]

Embedded image

(Example 1) 10 parts by weight of a zirconium alkoxide compound (trade name: Organix ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.) and a silane compound (trade name: A1110, manufactured by Nippon Unicar Co., Ltd.)
Parts by weight, a solution consisting of 40 parts by weight of isopropanol and 20 parts by weight of butanol was applied by a dip coating method, and dried by heating at 150 ° C. for 10 minutes.
An undercoat layer of μm was formed.

Next, the Bragg angles (2θ ± 0.2 °) of the X-ray diffraction spectrum using CuKα as a source are at least 7.4 °, 16.6 °, 25.5 °, and 28.3.
4 parts by weight of chlorogallium phthalocyanine microcrystals having a strong diffraction peak at a temperature of vinyl chloride-vinyl acetate copolymer (trade name: UCAR Solution Vinyl Resin VMC)
H, manufactured by Union Carbide) 2 parts by weight, xylene 67
Parts by weight, and 33 parts by weight of butyl acetate, and the mixture was dispersed with glass beads by a paint shake method for 2 hours. The obtained coating solution was applied on the undercoat layer by a dip coating method, and then heated to 100 ° C. For 10 minutes to form a charge generation layer having a thickness of 0.5 μm.

Next, a coating solution prepared by dissolving 20 parts by weight of the block copolymer having the charge transport block and the insulating block shown in Synthesis Example 3 in 80 parts by weight of toluene was applied onto the above-mentioned charge generating layer by dip coating. The resultant was applied and dried by heating at 115 ° C. for 30 minutes to form a 20 μm-thick heterogeneous charge transporting layer. Thus, an electrophotographic photoreceptor having a layer configuration as shown in FIG. 6 was produced.

The electrophotographic photoreceptor thus obtained was partially modified using an electrostatic copying paper test apparatus (Electrostatic Analyzer EPA-8100, manufactured by Kawaguchi Electric Works) at room temperature and normal temperature. Wet (20 ° C, 40%
(RH), the electrophotographic properties were evaluated. After adjusting the corona discharge voltage and charging the photoreceptor surface to -750 V, the halogen lamp light monochromatized to 750 nm through an interference filter was adjusted to have a light intensity of 1 mW / m ² on the photoreceptor surface. Irradiation for 7 seconds showed an S-shaped photoinduced potential decay as shown in FIG. The potential after light irradiation was defined as the remaining potential. From the photoinduced potential decay curve, the E _50% value was 3.5 mJ / m ² , and the E _50% / E _10% value was 1.
6 was calculated. The residual potential was -80V.

The cross section of this photoreceptor was stained with ruthenic acid and observed with a transmission electron microscope. As a result, it was found that the structure seemed to be a complicated and complicated modulation structure consisting of a dark part and a light part. This is presumed that the charge-transporting phase and the electrically inactive phase were phase-separated, and one of the phases was stained with rutenumic acid. The phase pitch was approximately 0.08 μm.

Comparative Example 1 The content of poly (n-dodecyl methacrylate) as an insulating block in the block copolymer was changed as shown in Table 5 by changing the amount of n-dodecyl methacrylate in Synthesis Example 3. A photoreceptor for electrophotography was prepared in the same manner as in Example 1 except that the above-described copolymer was used and a non-uniform charge transport layer was formed.

The cross section of this photoreceptor was stained with ruthenic acid and observed with a transmission electron microscope. As a result, it was found that the dark portion was a charge-transporting phase and the thin portion was a sea-island structure, which was an electrically inactive phase. It was observed.

Table 5 shows the results of the evaluation of the electrophotographic characteristics and the cross section of the heterogeneous charge transport layer of the electrophotographic photoreceptor thus obtained in the same manner as in Example 1.

Comparative Example 2 The content of poly (n-dodecyl methacrylate) as an insulating block in the block copolymer was changed as shown in Table 5 by changing the amount of n-dodecyl methacrylate in Synthesis Example 3. A photoreceptor for electrophotography was prepared in the same manner as in Example 1 except that the above-described copolymer was used and a non-uniform charge transport layer was formed.

The cross section of this photoreceptor was observed in the same manner as in Example 1. As a result, a structure seemed to be a sea-island structure in which the density was reversed from that of Comparative Example 1.

Table 5 shows the results of evaluating the electrophotographic characteristics and the cross section of the heterogeneous charge transport layer of the electrophotographic photoreceptor thus obtained in the same manner as in Example 1.

Comparative Example 3 An electrophotographic photosensitive member was produced in the same manner as in Example 1, except that the amount of n-dodecyl methacrylate as an insulating block in Synthesis Example 3 was changed to 0.

Table 5 shows the results of the evaluation of the electrophotographic characteristics and the cross section of the heterogeneous charge transporting layer of the electrophotographic photosensitive member obtained in the same manner as in Example 1.

[0121]

[Table 5]

As is clear from Table 5, the photoreceptor of Example 1 having the non-uniform charge transporting layer of the modulation structure of the present invention was excellent in S-characteristics and favorable in residual potential. On the other hand, the photoconductors of Comparative Examples 1 and 2 having the non-uniform charge transport layer
Either the character characteristic or the residual potential was inferior. The photoreceptor of Comparative Example 3, which did not include the insulating block, had a J-shaped photoinduced potential decay characteristic.

(Example 2) The film thickness of the heterogeneous charge transport layer was 5
A charge active layer and a heterogeneous charge transport layer were laminated on a substrate provided with an undercoat layer in the same manner as in Example 1 except that the thickness was set to μm.

Further, a coating solution prepared by dissolving 20 parts by weight of a compound composed of a repeating unit represented by the following structural formula (4) having a molecular weight of 80,000 as a polymer charge transporting material in 80 parts by weight of toluene was applied by an applicator. And dried at 115 ° C. for 1 hour to form a uniform charge transporting layer having a thickness of 15 μm. Thus, an electrophotographic photosensitive member having a layer structure as shown in FIG. 7 was produced.

[0125]

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When the electrophotographic photoreceptor thus obtained was evaluated in the same manner as in Example 1, the photoinduced potential decay characteristics were as follows: E _50% value: 3.3 mJ / m ² , E _50% /
The E _{10 %} value was 1.5 S-shaped. The residual potential was -40V.

Observation of the cross section of this photoreceptor in the same manner as in Example 1 showed a structure which seems to be a complicated and complicated modulation structure composed of a dark portion and a light portion. The phase pitch was approximately 0.08 μm.

Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a heterogeneous charge transport layer was formed using the copolymer of Synthesis Example 4 instead of the copolymer of Synthesis Example 3. did.

The electrophotographic photoreceptor thus obtained was evaluated in the same manner as in Example 1. The photoinduced potential decay characteristics were as follows: E _50% value: 3.9 mJ / m ² , E _50% /
It was S-shaped with an E _{10 %} value of 1.8. The residual potential was -50 V. The evaluation results are shown in Table 2 below.

Observation of the cross section of this photoreceptor in the same manner as in Example 1 revealed a structure considered to be a complicated and complicated modulation structure composed of a dark portion and a light portion. The phase pitch was approximately 0.08 μm.

Comparative Example 4 The content of poly (tert-butyl methacrylate) as an insulating block in the block copolymer was changed as shown in Table 6 by changing the addition amount of tert-butyl methacrylate in Synthesis Example 4. An electrophotographic photoreceptor was produced in the same manner as in Example 3, except that the obtained copolymer was used and a non-uniform charge transport layer was formed.

Observation of the cross section of this photoreceptor in the same manner as in Example 1 revealed that a structure seemed to be a sea-island structure in which the dark portion was a charge transporting phase and the thin portion was an electrically inactive phase. .

Table 6 shows the results of the evaluation of the electrophotographic characteristics and the cross section of the heterogeneous charge transport layer of the electrophotographic photoreceptor thus obtained in the same manner as in Example 1.

(Comparative Example 5) tert- in Synthesis Example 4
By using a copolymer in which the content of poly (tert-butyl methacrylate) as an insulating block in the block copolymer was changed as shown in Table 5 below by changing the amount of butyl methacrylate added, An electrophotographic photoconductor was prepared in the same manner as in Example 1, except that a transport layer was formed.

When the cross section of this photoreceptor was observed in the same manner as in Example 1, a structure seemingly a sea-island structure in which the density was reversed from that of Comparative Example 3 was observed.

Table 6 shows the results of the evaluation of the electrophotographic characteristics and the cross section of the heterogeneous charge transport layer of the electrophotographic photoreceptor thus obtained in the same manner as in Example 1.

(Comparative Example 6) The amount of tert-butyl methacrylate as an insulating block in Synthesis Example 4 was reduced to 0.
A photoconductor for electrophotography was produced in the same manner as in Example 1 except that the above conditions were satisfied.

Table 6 shows the results of the evaluation of the electrophotographic characteristics and the cross section of the heterogeneous charge transporting layer of the electrophotographic photosensitive member obtained in the same manner as in Example 1.

[0139]

[Table 6]

Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 2 except that a heterogeneous charge transport layer was formed using the copolymer of Synthesis Example 5 instead of the copolymer of Synthesis Example 1. did.

When the electrophotographic photoreceptor thus obtained was evaluated in the same manner as in Example 1, the photoinduced potential decay characteristics were E50 _% values of 4.2 mJ / m ² and E50 _%. /
It was S-shaped with an E _{10 %} value of 2.2. The residual potential was -70V.

When the cross section of this photoreceptor was observed in the same manner as in Example 1, a structure seemingly a complicated and complicated modulation structure consisting of a dark portion and a light portion was observed. The phase pitch was approximately 0.05 μm.

Example 5 An electrophotographic photosensitive member was prepared in the same manner as in Example 2 except that an aluminum drum was used in place of the aluminum substrate, and was applied to a laser printer (Laser Press 4105, manufactured by Fuji Xerox). It was mounted and a printing test was performed. At this time, an ND filter was provided in the optical path of the laser beam in order to obtain an optimal exposure amount. FIG. 13 shows a schematic configuration diagram of this laser printer.

Around the photosensitive drum 11, a pre-exposure light source (red LED) 12, a charging scorotron 13, an exposure laser optical system 14, a developing unit 15, and a transfer corotron 1
6 and the cleaning blade 17 are sequentially arranged in the order of the process. The exposure laser optical system 14 includes an exposure laser diode having an emission wavelength of 780 nm, and emits light based on a digitally processed image signal.
The emitted laser light 14a is configured to expose the surface of the photoconductor while being scanned by a polygon mirror, a plurality of lenses, and a mirror. Reference numeral 18 denotes a sheet.

Comparative Example 7 An electrophotographic photosensitive member was prepared in the same manner as in Comparative Example 3 except that an aluminum drum was used instead of the aluminum substrate, and a printing test was performed in the same manner as in Example 5.

When the quality of the prints obtained in Example 5 and Comparative Example 7 was compared visually, Example 5 was superior in terms of the reproducibility of fine lines and the like.

[0147]

The electrophotographic photoreceptor of the present invention is a photoreceptor exhibiting an S-shaped photoinduced potential decay characteristic, wherein the charge transport layer comprises a charge transporting phase and an electrically inactive phase. Inclusion of a block copolymer or a graft copolymer consisting of a charge transporting block and an insulating block in a phase-separated state having a structure, increasing the residual potential, lowering the photosensitivity,
An excellent effect of providing an electrophotographic photoreceptor having good S-characteristics without obstacles due to the separation of the charge transport path such as a decrease in charge transport speed can be provided.

Further, the electrophotographic apparatus using the S-shaped electrophotographic photoreceptor of the present invention obtains a printed image having excellent print quality and image quality by performing exposure based on a digitally processed image signal. be able to.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an exposure amount and a surface potential in a J-shaped electrophotographic photosensitive member.

FIG. 2 is a graph showing a relationship between an exposure amount and a surface potential in an S-shaped electrophotographic photosensitive member.

FIG. 3 is a two-dimensional schematic diagram showing a modulation structure including a charge transporting phase and an electrically inactive phase.

FIG. 4 is a schematic cross-sectional view showing an example of an electrophotographic photoreceptor of the present invention in which a charge generation layer and a non-uniform charge transport layer are sequentially provided on a support.

FIG. 5 is a schematic cross-sectional view showing an example of the electrophotographic photoreceptor of the present invention in which a charge generation layer, a charge transport layer composed of a heterogeneous charge transport layer and a uniform charge transport layer are sequentially provided on a support. .

FIG. 6 is a schematic cross-sectional view showing an example of the electrophotographic photoreceptor of the present invention in which an undercoat layer is provided between a support and a charge generation layer.

FIG. 7 is a schematic view showing an example of the electrophotographic photoreceptor of the present invention in which a charge generation layer, an undercoat layer, a charge transport layer composed of a heterogeneous charge transport layer and a uniform charge transport layer are sequentially provided on a support. It is sectional drawing.

FIG. 8 is a schematic cross-sectional view showing an example of the electrophotographic photoreceptor of the present invention in which a non-uniform charge transport layer and a charge generation layer are sequentially provided on a support.

FIG. 9 is a schematic cross-sectional view showing an example of the electrophotographic photoreceptor of the present invention in which a charge transport layer comprising a heterogeneous charge transport layer and a uniform charge transport layer and a charge generation layer are sequentially provided on a support. .

FIG. 10 is a schematic cross-sectional view showing an example of the electrophotographic photoreceptor of the present invention in which an undercoat layer is provided between a support and a heterogeneous charge transport layer.

FIG. 11 is a schematic cross-sectional view showing an example of the electrophotographic photoreceptor of the present invention in which an undercoat layer is provided between a charge transport layer composed of a support, a heterogeneous charge transport layer, and a uniform charge transport layer. .

FIG. 12 is a graph showing the photo-induced potential decay characteristics of Example 1.

FIG. 13 is a schematic configuration diagram of an electrophotographic apparatus of the present invention that performs exposure based on a digitally processed image signal used in an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Conductive support 2 ... Charge generation layer 3 ... Non-uniform charge transport layer 4 ... Uniform charge transport layer 5 ... Charge transport layer 6 ... Undercoat layer 11 ... Photoconductor drum 12 ... Light source for pre-exposure 13 ... Scorotron for charging 14 ... Laser optical system for exposure 15 ... Developer 16 ... Corotron for transfer 17 ... Cleaning blade 18 ... Paper

Continued on the front page (72) Inventor Fumiaki Taho 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd.

Claims (12)

[Claims] 1. An electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer provided on a conductive substrate, wherein the charge transport layer comprises a charge transporting phase and an electrically inactive phase. A heterogeneous charge transport layer containing a block copolymer or a graft copolymer comprising a charge transport block and an insulating block in a phase-separated state having a structure, and a 50% potential decay of the electrophotographic photosensitive member Is less than 5 times the exposure required for 10% potential decay,
An electrophotographic photoreceptor, comprising: 2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer comprises the heterogeneous charge transport layer and a uniform charge transport layer containing a charge transporting matrix. 3. The electrophotographic photosensitive member according to claim 2, wherein a charge generation layer, a non-uniform charge transport layer, and a uniform charge transport layer are sequentially laminated on the conductive substrate. body. 4. The charge transporting block in the block copolymer or graft copolymer comprising the charge transporting block and the insulating block contains a triarylamine structure as a repeating unit. 4. The electrophotographic photosensitive member according to any one of 1 to 3. 5. The charge transporting block in the block copolymer or the graft copolymer comprising the charge transporting block and the insulating block has at least one of the structures represented by the following general formula (1) or (2). 5. The electrophotographic photoreceptor according to claim 4, wherein the photoreceptor contains a seed as a repeating unit. Embedded image (Wherein, Ar ₁ and Ar ₂ each independently represent a substituted or unsubstituted aryl group, X ₁ is a divalent hydrocarbon group or a hetero atom-containing hydrocarbon group having an aromatic ring structure, X ₂ And X ₃ each independently represent a substituted or unsubstituted arylene group; L ₁ represents a divalent hydrocarbon group or a hetero atom-containing hydrocarbon group which may have a branched or ring structure; , 0 or 1 respectively
Means an integer selected from ) (In the formula, Ar ₃ and Ar ₄ each independently represent a substituted or unsubstituted aryl group, and L ₂ represents a trivalent hydrocarbon group having an aromatic ring structure or a heteroatom-containing hydrocarbon group.) 6. The insulating block in the block copolymer or the graft copolymer comprising the charge transporting block and the insulating block is made of a polymer of a vinyl monomer. The electrophotographic photosensitive member according to any one of the above. 7. The electrophotographic photoconductor according to claim 6, wherein the vinyl monomer contains at least one compound represented by the following general formula (3). Embedded image (Wherein, R ^{1 to} R ³ each independently represent a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl group or an aryl group, and R ⁴ represents a halogen atom, or a substituted or unsubstituted alkyl group or an aryl group. , An alkoxy group, an acyl group, an acyloxy group, or an alkoxycarbonyl group.) 8. The electrophotographic photoreceptor according to claim 2, wherein the uniform charge transporting layer contains a charge transporting polymer compound. 9. The charge-transporting polymer compound constituting the uniform charge-transporting layer contains at least one of the structures represented by the general formula (1) or (2) as a repeating unit. An electrophotographic photosensitive member according to claim 8. 10. The electrophotographic photosensitive member according to claim 1, wherein the charge generation layer contains a phthalocyanine compound as a charge generation material. 11. The exposure amount required for 50% potential decay is 10
The electrophotographic photoreceptor according to any one of claims 1 to 10, wherein the exposure amount is 3 times or less the exposure amount required for% potential decay. 12. An electrophotographic apparatus comprising: the electrophotographic photosensitive member according to claim 1; and an exposing unit that performs exposure based on a digitally processed image signal.