JP3440756B2 - Method for producing charge-transporting block copolymer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel charge transporting device that utilizes a charge transporting function and can be applied to electronic devices such as electrophotographic photoreceptors, electroluminescent devices, photorefractive devices, photosensors and photocells. The present invention relates to a method for producing a hydrophilic block copolymer.

[0002]

2. Description of the Related Art In recent years, electrophotography has been playing a central role in the fields of copying machines, printers, facsimiles, etc., because it has advantages such as high speed and high print quality.

As an electrophotographic photosensitive member used in the electrophotographic technique, 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 photoconductors using organic photoconductive materials, which are superior to these inorganic photoconductors in terms of cost, manufacturability, disposability, etc., has been actively conducted. At present, such organic photoconductors have surpassed inorganic photoconductors. In particular, the development of a function-separated layered structure in which two functions, that is, photocharge generation and charge transport, which are the elementary processes of photoconductivity, are carried by separate layers has increased the degree of freedom in material selection and Performance improvements have been achieved. In other words, it was difficult to design and develop a material that has both excellent charge generation and charge transport capabilities, but the adoption of the function-separated laminated structure enables optimization design that concentrates on each single function. It has become possible to obtain a high-performance electrophotographic photoreceptor.

As the charge generation layer for the function-separated laminated organic photoreceptor, a pigment having excellent charge generation ability such as a quinone pigment, a perylene pigment, an azo pigment, a phthalocyanine pigment, and selenium is directly deposited by vapor deposition or the like. A film-formed product or a high-concentration product dispersed in a binder resin has been put into practical use. On the other hand, as the charge transport layer, those in which a low molecular compound having excellent charge transport ability such as a hydrazone compound, a benzidine compound, an amine compound, and a stilbene compound are molecularly dispersed in an insulating resin have been put into practical use. .

By the way, in a conventional analog type electrophotographic copying machine which optically exposes an original by forming an image on a photosensitive member, in order to improve the reproducibility of halftones by density gradation, A photoconductor having a photo-induced potential decay characteristic as shown in FIG. 1, that is, a photoconductor that causes a potential decay in proportion to an exposure amount (hereinafter referred to as “J-shaped photoconductor”).
Is required. The above-mentioned inorganic photoreceptor and function-separated laminated organic photoreceptor exhibit the photoinduced potential attenuation characteristics shown in FIG.

However, in the digital type electrophotographic apparatus, which has been actively researched and developed in response to the recent demands for higher image quality, higher added value, networking, etc., in general, gradation is determined by the area ratio of dots or the like. Since the area gradation method is adopted, the potential is not attenuated until a certain exposure amount is reached as shown in FIG. 2, and a steep potential attenuation occurs when the exposure amount is exceeded, so-called S-shaped light induction. It is preferable to use a photoconductor having a potential attenuation characteristic (hereinafter, referred to as “S-shaped photoconductor”) from the viewpoint of improving the sharpness of pixels.

This S-shaped photo-induced potential attenuation characteristic is ZnO.
This is a known phenomenon in a single-layer type photoconductor in which an inorganic pigment such as phthalocyanine or an organic pigment such as phthalocyanine is particle-dispersed in a resin. M. Schaffert: "Ele
“Ctrophotography”, Focal Pr
ess, p. 344 (1975), J. W. Weig
l, J. Mammino, G .; L. Whittake
r, R. W. Radler, and J.M. F. Byrn
e: "Current Problems in Ele
ctrophotography ", Walter d
e Gruyter, p. 287 (1972)}. In particular, a large number of single-layer photoreceptors for laser exposure have been proposed in which a phthalocyanine-based pigment having photosensitivity in the near infrared region, which is the emission wavelength of a semiconductor laser which is widely used at present, is dispersed in a binder resin for laser exposure {eg, , Nguyen Chan Kae, Aizawa: The Chemical Society of Japan, p. 393 (1986), JP-A-1
No. 169454, No. 2-207258, No. 3-31847, No. 5-313387}.

However, although these single-layer type photoconductors are required to have both functions of charge generation and charge transport by a single material, as described above, materials having excellent performances in both functions are rare. Nothing that can withstand practical use has yet been obtained. In particular, since pigment particles generally have many trap levels, they have drawbacks such as low charge transport ability, residual charge, and low repeated stability. In order to fundamentally solve these problems, increase the degree of freedom in material selection, and eventually improve the overall photoconductor characteristics, it is essential to introduce a function separation structure also in the S-shaped photoconductor.

To solve this problem, D. M. Pai et al. Describes a two-layer laminated photoreceptor including a charge generation layer and a charge transport layer, wherein the charge transport layer includes at least two charge transport regions and one electrically inactive region, and the charge transport regions are mutually separated. By inventing that an S-shaped photo-induced potential attenuation characteristic can be realized in combination with an arbitrary charge generation layer by using a non-uniform charge transport layer formed by contacting to form a convoluted charge transport path, A forerunner was introduced to the introduction of the function separation structure into the photoconductor {JP-A-6-83077 (US Pat. No. 5,306,586)}. In addition, the present inventors
It was found that a three-layered laminated photoreceptor including a charge generation layer, a non-uniform charge transport layer, and a uniform charge transport layer exhibits S-shaped photoinduced potential attenuation characteristics, and the above-mentioned D. M. We succeeded in further increasing the degree of function separation from inventions such as Pai and proposed the invention on July 25, 1995 (Japanese Patent Application No. 7-2085).
52).

However, the function of making the photo-induced potential attenuation characteristic, which is a key in these inventions, S-shaped (hereinafter,
Specific examples of the heterogeneous charge transport layer that plays a role of "S-shaped" are as follows: phthalocyanine pigment microcrystalline resin dispersion film, hexagonal selenium microcrystalline resin dispersion film, polyvinylcarbazole-dodecylmethacrylate phase separation system block copolymer Only the combination is disclosed, and these materials have the following problems, and new development of the material for the nonuniform charge transport layer is indispensable in order to put the above invention into practical use. It is an issue.

That is, when a color pigment having a charge generating ability such as a phthalocyanine pigment or hexagonal selenium is used as the charge transport material for the heterogeneous charge transport layer, the charge transport layer is exposed from the charge transport layer side. In this case, the absorption of light in the nonuniform charge transport layer and the generation of charges associated therewith adversely affect the photosensitivity and chargeability, and cause problems such as deterioration in repeated stability. This problem can be avoided by using a charge generation layer having photosensitivity in a wavelength range where there is no absorption in the nonuniform charge transport layer and using an exposure apparatus that performs exposure only within the wavelength range. Will be constrained and fundamental improvement measures are desired. Further, in manufacturing a resin dispersion film of a phthalocyanine pigment or a resin dispersion film of hexagonal selenium, it is necessary to grind and / or disperse these pigments, but enormous energy is required for grinding and impurities are not mixed. There are risks. Furthermore, it is generally difficult to obtain a stable dispersion liquid, which requires a great deal of effort to search for a dispersion solvent or a binder resin, and also severely limits the selection material. Further, denaturation of the dispersion due to crystal growth or aggregation in the dispersion is generally unavoidable, and it cannot be used for a long period of time, resulting in an increase in cost.

On the other hand, a polyvinylcarbazole-dodecylmethacrylate phase-separated block copolymer is a special 2
Since it is synthesized using a functional initiator, there are problems such as difficulty in manufacturing and high cost. Further, there are problems that mechanical strength is weak, charge mobility is low, charge injection property is low, and the like. However, in the case of a phase-separated block copolymer, the coating solution is a uniform solution, which gives microscopic phase separation upon drying to give a desired heterogeneous charge transport structure. This has the advantage that the problems associated with crushing / dispersing are fundamentally eliminated. Further, since it is not a pigment, there is essentially no problem relating to light absorption that occurs when the above pigment is used.

As a charge-transporting polymer compound, polyvinylcarbazole has long been known to be effective as a charge-transporting material for electrophotographic photoreceptors, but its mechanical strength is weak and its charge mobility is low. There were practical problems such as small size and low charge injection property. As a means for solving this problem, the function of separating the charge transporting ability, which is the function required for the charge transporting layer, from the mechanical properties such as film-forming property, flexibility, and strength, and allowing each to be carried by different materials. Material development was carried out based on the idea of separation, and as described above, currently, low-molecular weight compounds having a high charge-transporting ability such as triarylamine and a polycarbonate having excellent film-forming property, flexibility, and strength are used. A molecular dispersion type composite material composed of a resin based resin has become the mainstream of a charge transport layer material for electrophotography. However, in such a molecular dispersion type composite material, there is a problem that the molecularly dispersed charge transporting low molecular weight compound is crystallized with time and / or heating, and the characteristics are deteriorated. Alternatively, application to devices that generate heat has been limited. In addition, when used in an electrophotographic photoreceptor for a liquid development type electrophotographic apparatus capable of obtaining high image quality, contact with the developer causes dissolution or crystallization of the charge transporting low molecular weight compound, resulting in charge transport. There was a problem that the layer was modified or cracked. Furthermore, in order to secure a sufficient charge transportability, it is necessary to disperse the charge transporting low molecular weight compound in the resin at a high concentration of 35 to 60 wt%, which has mechanical properties such as flexibility and strength. Even if an excellent resin was used, there was a limit to the mechanical properties of the composite film.

In order to utilize organic charge transporting materials widely in organic electronic devices including electrophotographic photoreceptors which are required to have longer life, higher durability and lower cost, the above problems should be overcome. Is indispensable, and in recent years, research and development of high-performance charge-transporting polymers as an alternative to polyvinylcarbazole have become active again as a means thereof. To date, based on the finding that triarylamine type charge transporting low molecular weight compounds have high charge transporting properties, many charge transporting polymers containing a triarylamine skeleton in the main chain or side chain have been developed. (Eg, US Pat. No. 4,80
No. 6,443, No. 4,806,444,
No. 4,801,517, No. 4,937,165
No. 4,959,288, JP-A-61
-20953, JP-A-1-134456,
1-134457, 1-134462, 4-133605, 4-133066, 8-176293, 8-176293.
Issue).

However, these charge transporting polymers are homopolymers or random copolymers obtained by mixing and copolymerizing several kinds of monomers, and they do not exhibit phase separation property, and they are independent. In, it is not possible to form a non-uniform charge transport layer for S-shape.

In order to solve this problem, the present inventors have found that a phase-separable polymer blend obtained by adding an insulating polymer that is incompatible with the charge-transporting polymer to those charge-transporting polymers is S-shaped. It was invented that it can function as a non-uniform charge transport layer (Japanese Patent Application Nos. 8-58858 and 8-158520). However, the polymer blend has a problem in manufacturing reproducibility that the phase separation scale is greatly changed depending on the film forming conditions such as the drying speed and the drying temperature, and the electrophotographic characteristics are greatly changed accordingly.

[0018]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances in the prior art, and is a novel charge transporting block copolymer capable of overcoming the above problems. It is an object of the present invention to provide a manufacturing method of.

That is, an object of the present invention is to provide a function-separated type electrophotographic photosensitive member containing at least a charge generating material and a charge transporting material, which is an electrophotographic photosensitive member excellent in high performance and durability, particularly an S-shaped electrophotographic photosensitive member. It is an object of the present invention to provide a manufacturing method capable of synthesizing a charge-transporting block copolymer as a charge-transporting material suitable for the body at low cost and with high purity.

[0020]

Means for Solving the Problems As a result of intensive investigations by the present inventors regarding charge transport materials and polymer materials,
A block copolymer consisting of a charge transporting block containing a triarylamine structure and an insulating block has excellent overall properties as a charge transporting material. Particularly, those blocks incompatible with each other are for S-shaped photoreceptors. It was found that it is suitable as a material for the non-uniform charge transport layer of the above, and it was disclosed on November 1, 1996 (Japanese Patent Application No. 8-292112, Japanese Patent Application No. 8-29112).
2113).

As a result of subsequent studies, it was found that the above-mentioned problems can be achieved by the following method for producing a block copolymer, and the present invention has been completed.

That is, the method for producing a charge-transporting block copolymer of the present invention is a method for producing a charge-transporting block copolymer containing a charge-transporting block and an insulating block, wherein a reactive functional group is added to the terminal. A charge transporting polymer having
A charge transporting polymer initiator having a polymerization initiation group at the terminal is obtained from a low-molecular polymerization initiator having an asymmetric structure having one functional group capable of reacting with the functional group, and the polymer initiator is an insulating monomer. The charge-transporting block copolymer can be produced from any charge-transporting polymer as long as it is capable of introducing a reactive functional group at its terminal. Among them, the most characteristic feature of the present invention is to use a low molecular weight polymerization initiator having an asymmetric structure having one functional group capable of reacting with the functional group of the charge transporting polymer.

Furthermore, the production method of the present invention has a wide range of applications, and it is possible to easily produce block copolymers having various structures according to the purpose. Further, the block copolymer produced by the production method of the present invention has a small amount of impurities mixed therein and exhibits excellent properties when applied to an organic electronic device such as an electrophotographic photoreceptor.

The high-purity charge-transporting block copolymer according to the present invention has a higher charge-transporting ability due to the charge-transporting block containing a triarylamine structure, and at the same time, an alloying method of introducing an insulating block is used. It is possible to control mechanical strength, glass transition temperature, crystallinity, refractive index, adhesiveness, adsorptivity, flexibility, solubility, meltability, phase separation state, etc. without impairing the charge transport ability. (For a simple homopolymer or random copolymer, these properties are
It is difficult to control without affecting the transport capacity). Further, by copolymerizing a component exhibiting other desired properties, it is possible to develop it into a material with higher functionality.

As the charge transporting block containing a triarylamine structure, a block containing at least one of the structures represented by the general formulas (2) and (3) as a repeating unit is particularly preferred as a charge transporting block. It is preferable from the point.

As the insulating block, a block obtained by polymerizing at least one kind of the vinyl monomer represented by the above general formula (4) is preferable from the viewpoint of mechanical strength, flexibility, transparency and the like.

The low molecular weight polymerization initiator used in the present invention has one functional group capable of reacting with the terminal functional group of the charge transporting polymer to be used, and initiates the polymerization of the intended insulating monomer. Any compound may be used as long as it can be obtained, but the asymmetric azo compound represented by the above general formula (1) is preferable from the viewpoints of abundance of polymerizable monomer species, ease of polymerization operation, storage stability and the like. Particularly, in the general formula (1), L is an aromatic group, and Y is any selected from the partial structural formula (1), a Y radical (that is, X-L-N = N−Y → X−L ・ + N ₂
+ · Y) has a low polymerization initiation ability, and has an advantage that a by-product of a homopolymer of an insulating monomer, which cannot be avoided by a polymerization initiator having a symmetrical structure, can be suppressed. The inclusion of a homopolymer in the block copolymer not only changes the phase separation state, but when used in a laminated structure, it causes adverse effects on the injection property due to segregation at the interface and significantly deteriorates the photoreceptor characteristics. . When the mixed homopolymer has a difference in solubility from the desired block copolymer, it is possible to separate the two by a method such as reprecipitation treatment and / or extraction treatment. Losses and cost increase due to the separation process. Furthermore, if there is no difference in solubility between the two, it is difficult to separate them, and the above-mentioned adverse effects on the characteristics of the photoreceptor cannot be avoided.

Such a copolymer can be suitably used as a charge transport material for various organic electronic devices such as an electrophotographic photoreceptor, an organic EL element, an organic photorefractive element, an organic photosensor and the like.

In particular, the copolymer in which the charge transporting block and the insulating block are incompatible gives a submicron-scale microphase-separated structure, and the laminated type photoreceptor using it as a nonuniform charge transporting layer is , S-shaped photoconductor, and can fundamentally solve the problems of the conventional S-shaped photoconductor described above.

Regarding the mechanism of the appearance of the S-shaped photo-induced potential attenuation characteristic, the trap theory {for example, Kitamura, Komon: The Electrophotographic Society of Japan, Vol. 20, p. 60 (1982)}, D
． M. Although there are some proposals such as the convoluted electric conduction theory proposed by Pai et al. In the above-mentioned patent, there is no established theory yet.

However, the above-mentioned pigment-resin-dispersed single-layer photoconductor which has been reported as an S-shaped photoconductor,
D. M. In the laminated photoreceptor including the charge generation layer such as Pai and the nonuniform charge transport layer, and the laminated photoreceptor including the charge generation layer, the nonuniform charge transport layer and the uniform charge transport layer of the authors, at least adjacent to the charge generation region. It can be recognized that the charge transport path of the charge transport region has a nonuniform structure in which the charge transport domains are dispersed in the electrically inactive matrix. still,
The term "electrical inactivity" as used herein means that the transport energy level of the charge transport domain is far from the transport energy level of the charge transport domain. It means that it is in a virtually electrically isolated state.

Why is the S-shaped photoinduced potential decay of the laminated type photoreceptor using the phase-separated heterogeneous charge transport layer containing the copolymer of the incompatible charge transporting block and the insulating block of the present invention. Although it is not always clear whether the characteristics are exhibited, D.I. M. According to the convoluted electric conduction theory advocated by Pai et al.
The process in which S-shaped photo-induced potential decay occurs is presumed to be as follows.

First, in the heterogeneous charge transport layer, it is considered that the charge transport domains dispersed in the electrically inactive matrix are in contact with each other to form a convoluted charge transport path. In this case, when the electrophotographic photoreceptor is charged and a high electric field is applied to the photosensitive layer, the charges generated in the charge generation layer by exposure are injected from the charge generation layer into the charge transport layer along the electric field due to the Coulomb force of the electric field. And move in the electric field direction in the charge transporting domain. However, when it reaches the terminal convex portion of the charge transporting domain, it encounters the barrier of the electrically inactive matrix and the movement direction is regulated by the electric field, so that the movement of the charge is temporarily stopped here. . If the moving distance during this period is sufficiently small with respect to the total thickness of the photosensitive layer, the potential attenuation during this period can be ignored.
After the charges corresponding to almost all surface charges are injected,
The local electric field perpendicular to the surface in the vicinity of the injected charges becomes negligibly small, and the stopped charges can escape the binding due to the electric field and diffuse in a direction other than the direction perpendicular to the surface, and become convoluted. It follows a continuous connecting path and reaches deeper than where the charge was first stopped. In this deep part,
As before, the charges are again exposed to a sufficiently high electric field and move in the domain along the direction of the electric field, again meeting the barrier of the electrically inactive matrix, and stopping the movement. However, since the electric field strength is lowered by the movement of other charges similar to the above, more charges pass through the convoluted charge transport path and reach the next insulating barrier. Thus, the charge transfer occurs in cascade, resulting in an S-shaped photoinduced potential decay. The above is the D. M.
It is an explanation by Pai and the like. In the pigment-resin-dispersed single-layer S-shaped photoreceptor, the exposure light is absorbed in the vicinity of the surface and charges are generated there. The remaining region can be considered as a charge transport layer and the above statements apply as well.

The photo-induced potential decay of the S-shaped laminated photoreceptor using the phase-separated heterogeneous charge transport layer containing the copolymer of the incompatible charge transport block and the insulating block of the present invention The behavior is presumed to be due to the above-mentioned phenomenon, in which the charge-transporting block phase forms the charge-transporting domain and the insulating block phase forms the electrically inactive matrix.

The S-characteristic of the photo-induced potential attenuation characteristic is, for example, an exposure amount E _50% required to attenuate the charging potential by 50% and an exposure amount E 10% required to attenuate the charging potential by _10%.
The ratio (E _50% / E _10% ) can be used. When the potential attenuation is proportional to the exposure amount in an ideal J-shaped photoconductor, the E _50% / E _10% value is 5. In a general J-shaped photoconductor, the charge generation efficiency and / or
Alternatively, the E _50% / E _10% value exceeds 5 because the charge transporting ability decreases.

On the other hand, a certain exposure amount, which is the ultimate of S-shape,
In that case, the potential is not attenuated at all, and the residual potential level is suddenly increased by the exposure amount.
With a stepwise photo-induced potential decay curve that decays to the bell
Is E _50%/ E_Ten%The value is 1. Therefore, S-shaped
Is E_50%/ E_Ten%A value of 1 or more and less than 5
It is prescribed by. The desirable digital characteristics as described above
E to show_50%/ E_Ten%Value must be less than 3
Is preferred, and a value less than 2 is more preferred. However
However, analog characteristics are used in combination for the purpose of enhancing gradation.
E, if_50%/ E_Ten%The value is approximately 1.5-4
Within the range, it gives a favorable result. S-shaped electrophotography of the present invention
The photoreceptor is such a preferred E_50%/ E_Ten%Can take a value
It

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to embodiments.

The charge-transporting block of the charge-transporting copolymer preferably used in the present invention may be any one as long as it has a charge-transporting ability, but its repeating unit contains a triarylamine structure. Further, the block has a molecular weight of 2000 or more, particularly at least one of the structures represented by the following general formula (2) or (3):
What contains a species as a repeating unit is a charge mobility,
It is preferable in terms of charge injection property, charge life, visible light and infrared light transparency, chemical stability and the like.

[0039]

[Chemical 6]

In the formula, Ar ¹ and Ar ² each independently represent a substituted or unsubstituted aryl group, X ¹ represents a divalent hydrocarbon group having an aromatic ring structure or a hetero atom-containing hydrocarbon group, X ² and X ³ each independently represent a substituted or unsubstituted arylene group, L ¹ represents a divalent hydrocarbon group which may have a branched or ring structure or a hetero atom-containing hydrocarbon group, and m and n represents an integer selected from 0 and 1, respectively.

[0041]

[Chemical 7]

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 hetero atom-containing hydrocarbon group.

In the above general formula (2), Ar ¹ and Ar ² are each independently selected from a substituted or unsubstituted aryl group, and specific examples of the aryl group include phenyl group, biphenyl group, naphthyl group and pyrenyl. Groups and the like.
Further, examples of the substituent include a methyl group, an ethyl group, a methoxy group, a halogen atom and the like. Among them, an unsubstituted phenyl group and a methyl group-substituted phenyl group are preferable from the viewpoint of effects.

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,
Examples thereof include a thiodiphenyl group and the like, and a methyl-substituted product, an ethyl-substituted product, a methoxy-substituted product, and a halogen-substituted product thereof. Among them, a substituted or unsubstituted biphenylene group is particularly preferable from the viewpoint of charge transportability.

X ² and X ³ are each independently selected from a substituted or unsubstituted arylene group, and specific examples thereof include a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group and the like, and a methyl-substituted product thereof, ethyl. Substitutes, methoxy substitution, halogen substitution, etc. are mentioned. Among them, a phenylene group is preferable from the viewpoint of effect.

L ¹ is selected from a divalent hydrocarbon group which may contain a branched structure or a ring structure or a hydrocarbon group containing a hetero atom, and is arbitrary as long as it exhibits at least one of the above-mentioned preferable characteristics. Those having 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 thereof include the following.

[0047]

[Chemical 8]

In the general formula (3), Ar ³ and Ar ⁴ are each independently selected from a substituted or unsubstituted aryl group, and specific examples of the aryl group include phenyl group, biphenyl group, naphthyl group and pyrenyl. Groups and the like.
Moreover, as a substituent, a C1-C12 alkyl group or an alkoxy group, a diarylamino group, a halogen atom etc. are mentioned.

L ² is selected from a trivalent hydrocarbon group having an aromatic ring structure or a hetero atom-containing hydrocarbon group, and is arbitrary as long as it exhibits at least one of the above-mentioned preferable characteristics, but it has 20 carbon atoms. The following are preferred. Specific examples thereof include the following.

[0050]

[Chemical 9]

The insulating block forming the copolymer of the present invention may be of any type as long as it is insulative and has a molecular weight of 2,000 or more. Mechanical strength, flexibility, visible light and In particular, those obtained by polymerizing a vinyl monomer represented by the following general formula (4) are preferable in terms of infrared light transmittance, chemical stability, insulating properties, and the like.

[0052]

[Chemical 10]

In the formula, R ^{1 to} R ³ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group,
Or a substituted or unsubstituted aryl group, R ⁴ is a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted acyl group, a substituted Alternatively, it represents an unsubstituted acyloxy group, or a substituted or unsubstituted alkoxycarbonyl group.

Among the above-mentioned general formula (4), R ^{1 to} R ³ are preferably hydrogen atom or methyl group from the viewpoint of effects. Specific examples of the substituted or unsubstituted alkyl group or aryl group include a methyl group, an ethyl group, a chloromethyl group, a phenyl group and a tolyl group.

In R ⁴ , an alkyl group, an alkoxy group, an acyl group, an acyloxy group and an alkoxycarbonyl group preferably have 1 to 18 carbon atoms, and examples of the aryl group include a phenyl group, a naphthyl group and a pyrenyl group. To be Examples of the substituent include a halogen atom, a phenyl group, a hydroxy group, an amino group, an isocyanate group, an epoxy group, an alkoxysilyl group and the like.

As long as the copolymer used in the present invention is a block copolymer, any form of connecting the constituent blocks may be used. That is, the charge transporting block is A,
Insulating block is B, AB type diblock copolymer,
ABA-type and BAB-type triblock copolymers, and (AB) n-type, (AB) nA-type and B (AB) n-type multiblock copolymers, or ABA in the side chain of the block copolymer such as ABA type And / or B-grafted block-graft copolymers and the like.

The method for producing the block copolymer of the present invention includes the initiation of a low-molecular polymerization of an asymmetric structure having a charge transporting polymer having a reactive functional group at the terminal and one functional group capable of reacting with the functional group. Any method may be used as long as the charge-transporting polymer initiator having a polymerization initiating group at the terminal is obtained from the agent and the insulating monomer is polymerized from the polymer initiator. Regarding individual elementary reactions, any knowledge in synthetic chemistry can be utilized (eg, 4th edition Experimental Chemistry Lecture 28 Polymer Synthesis (Maruzen, 1992), Macromonomer Chemistry and Industry (IPC, 1990), Molecular compatibilization and evaluation technology (Technical Information Society, 1992), new polymer material On
e Point 12 Polymer Alloy (Kyoritsu, 198
8) etc.}.

As a method for synthesizing the charge-transporting polymer having a reactive functional group at the terminal, any method can be used. For example, in the case of polycondensation-type and addition-condensation-type polymers, the terminal is essentially a reactive functional group. If it is an addition polymerization type polymer, a compound having both a group capable of reacting with the active terminal of the growing polymer and a desired reactive functional group is used, and the desired reactive functional group is changed by stopping the polymerization. A polymer having a terminal can be obtained. A polymer having a desired reactive functional group at the terminal can also be obtained by carrying out addition polymerization using a polymerization initiator having a desired reactive functional group. Specific examples of the reactive functional group include a hydroxy group, a carboxyl group, a carbonyl halide group, an amino group, an epoxy group, an isocyanate group, a melamine group, a phenol group, a methyl halide group,
Examples thereof include an alkoxysilyl group and an alkoxycarbonyl group. Of these, a hydroxy group, a carboxyl group and a carbonyl halide group are preferable from the viewpoint of the effect. The reactive functional groups may be the same or different at both ends of the charge transporting polymer. Further, it may be present only at one end.

The functional group capable of reacting with the terminal functional group of the charge transporting polymer essential for the low molecular weight polymerization initiator used in the present invention is a reactive bond with the terminal functional group of the target charge transporting polymer. Anything is possible as long as it is possible. Specific examples include a hydroxy group, a carboxyl group, a carbonyl halide group, an amino group, an epoxy group,
Examples thereof include an isocyanate group, a melamine group, a phenol group, a halogenated methyl group, an alkoxysilyl group and an alkoxycarbonyl group.

Further, the polymerization initiation group essential for the low molecular weight polymerization initiator used in the present invention may be any one as long as it can initiate the polymerization of the intended insulating monomer, and for example, an azo group. , Peroxy ester groups, peroxy groups, dithiocarbamate groups, metal oxyalkyl groups, metal alkyl groups, alkyl halides and the like. Azo, peroxyester, peroxy, dithiocarbamate and the like can initiate radical polymerization of vinyl monomers. Metal oxyalkyl, metal alkyl and the like can initiate ring-opening polymerization of cyclic ester monomers and cyclic amide monomers and anionic polymerization of vinyl monomers. When an alkyl halide or the like is used in combination with an appropriate coinitiator, cationic polymerization and radical polymerization of vinyl monomers can be initiated. Examples of the co-initiator include TiCl _{n in} cationic polymerization.
Examples thereof include Lewis acids such as (OR) _4-n , and Cu (I) complex and Ru (II) complex in radical polymerization. Among these, the azo group has high storage stability, does not require a special coinitiator, is relatively mild in polymerization conditions, and is particularly preferable in terms of reproducibility, cost, simplicity of polymerization apparatus, and the like. preferable.

Specific examples of the low molecular weight polymerization initiator of the present invention having an azo group as a polymerization initiation group include an asymmetric azo compound represented by the following general formula (1).

[0062]

[Chemical 11]

In the formula, X represents a functional group capable of reacting with the functional group at the terminal of the charge transporting polymer, and specific examples thereof are a hydroxy group, a carboxyl group, a carbonyl halide group, an amino group, an epoxy group and an isocyanate group. , Melamine group,
A group selected from the group consisting of a phenol group, a halogenated methyl group, an alkoxysilyl group and an alkoxycarbonyl group is shown. Of these, a hydroxy group, a carboxyl group, a carbonyl halide group, an amino group, an epoxy group, an isocyanate group, a methyl halide group, and an alkoxysilyl group are preferable from the viewpoint of effects. Further preferred is a carbonyl halide group.

L represents a divalent hydrocarbon group which may have a branched or ring structure or a hydrocarbon group containing a hetero atom, and is preferably a substituted or unsubstituted aromatic group.
In particular, a substituted or unsubstituted arylene group is preferable.

Y represents a monovalent heteroatom-containing hydrocarbon group, and one selected from the group consisting of the following partial structural formulas (1) is particularly preferable.

[0066]

[Chemical 12]

In the formula, R ^{1 to} R ¹¹ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted The alkoxycarbonyl group, the substituted or unsubstituted acyl group or the substituted or unsubstituted acyloxy group.

In R ^{1 to} R ¹¹ of Y, the alkyl group, the alkoxy group, the alkoxycarbonyl group, the acyl group or the acyloxy group preferably has 1 to 18 carbon atoms, and the aryl group is a phenyl group, a naphthyl group or a pyrenyl group. Etc. Specific examples of the substituent include a halogen atom,
Examples thereof include a cyano group, a nitro group and a phenyl group.

Of the above partial structural formulas (1), Y is preferably an alkyldicyanomethyl group (—C (CN) ₂ R) in terms of its effect.

Specific examples of the asymmetric azo compound represented by the combination of the partial structural formulas X, L and Y represented by the above general formula (1) include the following.

[0071]

[Table 1]

[0072]

[Table 2]

In Table X, R represents an alkyl group or aryl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms.

Among the asymmetric azo compounds, (halogenated carbonylphenylazo) -alkyldicyanomethyl is preferable from the viewpoint of effect.

By the way, a general azo initiator is 2,2 '.
-Azobis (isobutyronitrile), 4,4'-azobis (4-cyanopentanoic acid chloride), etc., which have a structure symmetrical to the azo group, but these symmetrical structure azo initiators (denoted by I) Is used, when it is reacted with a charge transporting polymer having functional groups at both ends (denoted by P), P-
I, I-P-I, P-I-P, and (IP) n are generated at the same time. The production of those having a plurality of Ps causes an increase in solution viscosity, which causes problems such as difficulty in handling and purification. Further, in the azo initiator having a symmetrical structure, the polymerization initiation abilities of two radicals generated by denitrification are the same, and an insulating property is obtained from a polymer initiator having an I terminal such as P-I and I-P-I. When the monomer is polymerized, there is a problem that a homopolymer of an insulating monomer is by-produced in addition to the block copolymer. The low-molecular-weight polymerization initiator used in the production method of the present invention has only one functional group capable of reacting with the terminal functional group of the charge-transporting polymer and has an asymmetric structure, and the above-mentioned problems are basically solved. . That is, a charge transporting polymer having functional groups at both ends and an azo initiator having an asymmetric structure having only one stoichiometric amount of functional group (denoted by I ')
I'-P-I 'can be obtained by reacting with the azo group, and further, the azo group having an asymmetric structure, that is, the P-L radical produced by denitrification of I'has a polymerization ability and is simultaneously produced. Since the Y radical has no polymerization ability, a by-product of a homopolymer of an insulating monomer can be suppressed and a desired block copolymer can be obtained with high purity.

As a method for synthesizing the asymmetric azo initiator,
R. Keber, O.M. Nuyken, M .; Dorn: M
acromol. Chem. , 179, 1803 (19
78), N.C. Fery, R .; Hoene, K .; Hama
nn: Angew. Chim. Internat. Ed
it. , 11, 337 (1972), O.I. Nuyke
n, U. Presenz: Polym. Bull. , 2
0,335 (1988), O.I. Nuyken, L .; Dy
ckerhoff, R.A. Kerber: Angew. M
acromol. Chem. , 143, 11 (198
6), any method such as the method described in the literature such as JP-A-8-59836 can be used.

The molecular weight of the copolymer of the present invention may be any value, but it is preferably 2000 or more in order to exert the polymer characteristics such as mechanical strength and film-forming property. There is no particular limitation on the upper limit of the molecular weight in terms of electrical characteristics, but when forming a film by a wet coating method, it is necessary that it be within a range that gives an appropriate solution viscosity, and generally,
It is preferably 5,000,000 or less.

As is well known in the field of polymer blends, polymer alloys, different macromolecules are generally incompatible with each other, and their mixtures and block or graft copolymers exhibit phase separated states. take. Generally, in a simple mixture, that is, a polymer blend, the phase separation scale is macroscopic with a size of several μm or more (macro phase separation). On the other hand, in the block copolymer and the graft copolymer in which each component is covalently linked, a phase separation state composed of fine domains of submicron or less is given (micro phase separation). The scale of phase separation in block copolymers and graft copolymers is generally the same dimension as the average length of each block, and the molecular weight is 2
It is known to be approximately proportional to the root of the third power.

The block copolymer according to the present invention also generally takes a microphase-separated state. However, the block copolymer according to the present invention is not limited to one that always takes a microphase-separated state, but includes one that exhibits compatibility and does not cause phase separation depending on the combination of blocks.

The block copolymer produced by the production method of the present invention has both a high charge-transporting ability and excellent mechanical properties, and thus is suitably used for various organic electronic devices. Particularly, it is preferably used for a function-separated electrophotographic photoreceptor. For example, a material having both high charge transporting property, film-forming property, pigment adsorbing property, and adhesive property can be used as an excellent single-layer type photoconductor and multi-layer type photoconductor by being used in combination with a pigment having charge generation capability. To provide a charge generation layer for. Further, a material having both high charge transportability, mechanical strength, chemical strength and low surface energy is effective as a material for the charge transport layer or the surface protective layer. In particular, an insulating block having a crosslinking site such as a hydroxy group or an alkoxysilyl group introduced therein is cross-linked and cured to give a very strong charge transporting film, which is particularly preferable as the surface protective layer. Furthermore, the charge transporting block is a domain,
As described above, a material in which the insulating block provides a microphase-separated state serving as a matrix is preferably used as the nonuniform charge transport layer for the function-separated S-shaped photoreceptor.

3 to 6 are schematic views showing the cross section of the S-shaped electrophotographic photosensitive member of the present invention. In FIG. 3, the charge generation layer 2 is provided on the conductive support 1, and the non-uniform charge transport layer 3 responsible for S-shape and charge transport is provided thereon. In FIG. 4, a charge generation layer 2 is provided on a conductive support 1, a non-uniform charge transport layer 3 responsible for S-shape is provided thereon, and a uniform charge responsible for main charge transport is further provided thereon. A transport layer 4 is provided. In FIG. 5, the nonuniform charge transport layer 3 is provided on the conductive support 1, and the charge generation layer 2 is provided thereon. In FIG. 6, the uniform charge transport layer 4 is provided on the conductive support 1, the nonuniform charge transport layer 3 is provided thereon, and the charge generation layer 2 is further provided thereon.

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

As described above, the movement distance until the charge generated in the charge generation layer encounters the obstacle of the electrically inactive matrix of the nonuniform charge transport layer and is first stopped is the total film thickness of the photosensitive layer. On the other hand, if it is sufficiently small, the potential decay during that period becomes negligible, and a more ideal S-shape is exhibited.
That is, 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 appropriate intermediate layer may be provided between the charge generation layer and the heterogeneous charge transport layer for the purpose of injecting charges or assisting the generation of charges. Further, by inserting a uniform charge transport layer between the charge generation layer and the non-uniform charge transport layer and changing the film thickness of the uniform charge transport layer, the E _50% / E _10% value is within the range of 1 to 5. It is also possible to set any value of.

The S-shaped charge-transporting layer is a layer for forming a charge-transporting path characterized by a nonuniform structure in which charge-transporting domains are dispersed in an electrically inactive matrix. Among the block copolymers composed of the insulating block and the charge transporting block produced by, both blocks are formed incompatible with each other and give a micro phase separation structure.

In the S-shaped charge transport layer, formation of the convoluted charge transport path depends on stochastic contact between charge transport domains. If the contact rate is too high, the charge transport path will not be convoluted and the S-shape will be reduced. If the contact rate is too low, a continuous charge transport path cannot be formed through the entire transport layer, increasing the residual potential. Invite. The charge transporting domains do not necessarily have to be in direct contact with each other, a very thin insulating layer between the charge transporting domains is provided that charges can jump over the gap and trapping there is negligible. Its existence is acceptable. The convoluted charge transport path mentioned here is a charge transport path formed so that the movement of charges reverses once or more in the film thickness direction.

As the insulating block forming the electrically inactive matrix, any electrically inactive block with respect to the main transport charge may be used, but 10 ¹³ Ω · cm
Those having a volume resistivity of the above are preferable, and those having a volume resistivity of 10 ¹⁴ Ω · cm or more are more preferable. When the volume resistivity is lower than 10 ¹³ Ω · cm, the electrically insulative property of the electrically inactive matrix is insufficient, and the S-shaped property tends to be lost or the dark decay tends to increase.

Specific examples of the insulating block include polyolefin, polyvinyl acetal, polyalkyl methacrylate, polyalkyl acrylate, polyvinyl chloride, polystyrene, polyvinyl acetate, polyalkyl vinyl ether, polycarbonate, polyester, polysiloxane, and the like. Examples thereof include block, graft, random or alternating copolymers, and the polymer obtained from the monomer represented by the general formula (4) is particularly preferable in terms of mechanical strength, flexibility, phase separation property and the like. preferable.

The charge-transporting block forming the charge-transporting domain may be any block as long as it has a charge-transporting ability. However, a block having a triarylamine structure is a charge-transporting block and is chemically stable. And the like, and among them, those having a structure represented by the general formula (2) or (3) are particularly preferable.

The composition ratio of the charge transporting block and the insulating block in the block copolymer used for the S-shaped photoreceptor of the present invention is determined by the charge transporting domain and the electrical inactivity obtained as a result of their phase separation. Matrix volume ratio is 10 /
It is arbitrarily set within the range of 1 to 1/10. A more preferable range of the volume ratio of the charge transporting domain to the electrically inactive matrix is 4/1 to 1/2. If the volume ratio of the charge-transporting domain is larger than the above range, the charge-transporting domains are in intimate contact with each other or the charge-transporting block becomes a matrix to form a charge-transporting path having a substantially uniform structure. The inhomogeneous structure of the charge transport path, which is essential for the expression of the S-shaped photo-induced potential attenuation characteristic, is not formed, and the S-shaped property tends to be lost. On the other hand, when the volume ratio of the charge transporting domain is less than the above range, the charge transporting path is divided,
It tends to cause problems such as an increase in residual potential and a decrease in response speed.

The phase separation structure of the nonuniform charge transport layer is as follows:
Any structure may be used as long as the charge transporting block serves as a domain and the insulating block serves as a matrix, but a sea-island structure in which the phase comprising the charge transporting block is an island and the phase comprising the insulating block is the sea Better S-shaped property can be obtained when the phase separation structure of is adopted. Also, when taking the modulation structure obtained by spinodal decomposition,
A desirable S-shaped property is obtained.

The phase-separated state has a thermodynamically most stable structure depending on the type and molecular weight of the building blocks. Generally, in a copolymer composed of A block and B block, it does not depend on the connection form. , A / B composition ratio only,
As the A / B ratio increases, A is a spherical domain, B is a matrix, A is a rod-shaped domain, B is a matrix, and A / B
Systematically changes to alternating layers, B is a spherical domain, A is a matrix, B is a rod-shaped domain, and A is a matrix.

However, when the film is formed by the wet coating method, the phase separation state can be arbitrarily controlled by the solvent used, the drying speed, and the like. For example, even when the A / B ratio is large and the B-sphere A matrix structure is taken thermodynamically, if a solvent that is a good solvent for B and a poor solvent for A is selected as the coating solvent, the A-sphere B matrix will be obtained. The structure can be obtained. In addition, when a good solvent for both A and B is used and the solvent is rapidly removed, a phase separation structure (modulation structure) frozen in a spinodal decomposition state can be obtained.
When a polymer having a high A / B ratio and a thermodynamically B-sphere A matrix structure is added with a polymer compatible with only B, A is compatible with only spheres, B and B. It is also possible to obtain a phase-separated structure in which a polymer serves as a matrix.

The film thickness of the S-shaped charge transport layer used in the present invention is suitably 0.1 to 50 μm, preferably 0.1.
It is set in the range of 2 to 15 μm, more preferably 0.5 to 5 μm. If the thickness is less than the above range, the S-characteristic tends to decrease. The upper limit of the film thickness is limited by the charge transport ability of the S-shaped charge transport layer used, and is set within a range in which the response speed, the residual potential, etc. are allowed.

The average diameter of the charge transporting domain is 0.005.
~ 3μm is preferred, more preferably 0.007-1μ
m, particularly preferably 0.01 to 0.5 μm. When the average diameter of the charge transporting domain is larger than the above range, the formation of the non-uniform structure of the charge transporting path necessary for S-shape formation within a preferable film thickness range is stochastically lowered and the S-shape is deteriorated. It will be. On the other hand, when the average diameter of the charge transporting domain is smaller than the above range, the charge transporting path approaches a uniform structure and the S-characteristic is deteriorated.

The charge mobility of the charge-transporting domain is one factor that governs the response speed of the electrophotographic photosensitive member, and the higher the mobility, the more suitable it is used in a high-speed electrophotographic apparatus. In the electrophotographic apparatus of the present invention, it is preferably at least 10 ^-6 cm ² / Vs in at least the electric field intensity range used for development. More preferably 5 × 10 ^-6 cm
² / Vs or more. It is difficult to directly measure the charge mobility of the charge transporting domain, and the charge mobility of the charge transporting polymer having the same structure as the charge transporting block can be used as a substitute.

By adding a compound capable of transporting only a charge having a polarity opposite to that of the main transport charge into the S-shaped charge transport layer, effects such as reduction of residual potential and improvement of repeated stability can be obtained. You can also

In addition to the charge transporting block copolymer, a charge transporting polymer and / or an insulating polymer may be added to the S-shaped charge transporting layer. When the charge transporting polymer is added, it is preferably compatible with the charge transporting block of the block copolymer. When an insulating polymer is added, it is preferable that the insulating polymer has compatibility with the insulating block of the block copolymer.

Examples of the method for applying the nonuniform charge transport layer include blade coating method, ring coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method and curtain coating method. Conventional methods can be used. The coating solution can be a uniform solution or a micellar solution.

The conductive support used in the electrophotographic photosensitive member of the present invention can be selected from any type that can be used as such a support in the art, and can be opaque or substantially transparent. Specific examples include metals such as aluminum, nickel, and stainless steel; aluminum, titanium, nickel, chromium, stainless steel, gold, platinum, zirconium, vanadium, tin oxide, plastics provided with thin films of indium oxide, ITO, and the like; Glass, ceramics, etc .; paper, plastic, glass, ceramics, etc. coated or impregnated with a conductivity-imparting agent can be mentioned. The shape of these conductive supports can be any suitable shape such as a drum shape, a sheet shape, and a plate shape. Various treatments can be applied to the surface of the conductive support, if necessary. For example, oxidation treatment, chemical treatment, coloring treatment, or mechanical roughening treatment such as graining, honing, rough cutting, or the like can be performed. Oxidation and mechanical roughening of the surface of the support not only roughen the surface of the support, but also control the surface shape of the layer applied on top of it, which can interfere with laser light as an exposure light source. When a light source is used, the effect of preventing the occurrence of interference fringes due to specular reflection on the surface of the support and / or the laminated interface, which is a problem, is exhibited.

An undercoat layer optionally provided between the conductive support and the photoconductive layer prevents injection of charges from the conductive support to the photosensitive layer when the photosensitive layer is charged, and It exhibits an action as an adhesive layer for integrally adhering and holding the photosensitive layer to the conductive support, or an action for preventing specular reflection of light which causes interference fringes in some cases.

As the above-mentioned undercoat layer, known layers can be used, and examples thereof include polyethylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, urethane resin,
Polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, polyvinyl alcohol resin, water-soluble polyester resin, alcohol-soluble nylon resin, nitrocellulose, polyacrylic acid, resins such as polyacrylamide and copolymers thereof, or zirconium alkoxide compound, Curable metal organic compounds such as titanium alkoxide compounds and silane coupling agents 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 charging polarity can also be used.

The thickness of the undercoat layer is suitably 0.01 to 10 μm, preferably 0.05 to 5 μm. As a coating method, a usual method such as a blade coating method, a ring 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 can be used.

The charge generating layer in the laminated electrophotographic photosensitive member of the present invention can be selected from any one that can be used as a charge generating layer in the laminated photosensitive member regardless of J-shape or S-shape. For example, amorphous selenium, selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and selenium alloys, zinc oxide, titanium oxide, a-Si, a-SiC.
Examples include inorganic photoconductive materials such as phthalocyanine, squarylium, anthanthrone, perylene, azo, polycyclic quinone, pyrene, pyrylium salt, thiapyrylium salt, and other organic pigments and dyes. . Also,
These charge generating materials may be used alone or in combination of two or more.

The phthalocyanine-based compound is LE which is currently widely used as a light source in digital electrophotographic devices.
The emission wavelength of D and the laser diode is 600-
Since it has excellent photosensitivity at 850 nm, it is particularly preferable as the charge generation material in the present invention. As the phthalocyanine-based compound, metal-free phthalocyanine, metal phthalocyanine, and derivatives thereof can be used. As the central metal of the metal phthalocyanine, Cu, Ni, Zn, C
o, Fe, V, Si, Al, Sn, Ge, Ti, In,
Ga, Mg, Pb, Li and the like are mentioned, and oxides, hydroxides, halides, alkylated compounds, alkoxylated compounds of these central metals are also effective. Specifically, titanyl phthalocyanine, chlorogallium phthalocyanine,
Examples thereof include hydroxygallium phthalocyanine, vanadyl phthalocyanine, chloroindium phthalocyanine, dichlorotin phthalocyanine and dimethoxysilicon phthalocyanine. Substituted phthalocyanines in which an arbitrary substituent is introduced into the phthalocyanine ring of the above compound can also be used. Furthermore, azaphthalocyanines in which any carbon atom in the phthalocyanine ring of the above compound is substituted with a nitrogen atom are also effective. As the form of these phthalocyanine compounds, amorphous or all crystalline forms can be used.

Among these phthalocyanine compounds,
Metal-free phthalocyanine, titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, and dichlorotin phthalocyanine have particularly excellent photosensitivity and are particularly preferable as the charge generating material used in the present invention.

Further, most of the phthalocyanine compounds have the property of a p-type semiconductor having holes as the main transport charge, whereas dichlorotin phthalocyanine, phthalocyanines having an electron-withdrawing group and azaphthalocyanines. Since it is an n-type semiconductor with electrons as the main transport charge,
An S-shaped photoreceptor including these phthalocyanine-based compounds as a charge generating material and having a charge generating layer and a charge transporting layer sequentially laminated on a conductive substrate has high sensitivity when used with negative charging. Injecting positive charges from the conductive support is suppressed, dark decay is small, and high chargeability is exhibited, thus exhibiting good electrophotographic characteristics.

Hexagonal selenium, anthanthrone-based pigment, polycyclic quinone-based pigment and perylene-based pigment are also excellent in charge generation efficiency and therefore can be preferably used as a charge generation material. Since the beam diameter of the laser light can be made smaller as the transmission wavelength becomes shorter, it is being studied to shorten the wavelength of the laser for exposure with the aim of achieving higher image quality. Since it has photosensitivity, it can be particularly preferably used as a charge generating material for a short wavelength laser.

The charge generation layer can be formed by directly forming the charge generation material by a vacuum vapor deposition method or by dispersing or dissolving the charge generation material in a binder resin.

When a binder resin is used for the charge generation layer, the kind of the binder resin is not particularly limited, and examples thereof include polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal resin, polycarbonate resin, polyester resin, acrylic resin. , Polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin,
Polyvinyl acetate resin, silicone resin, phenol resin, polyvinyl carbazole resin and the like are used. These binder resins may be block, random or alternating copolymers, and these binder resins may be used alone or in combination of two or more. Further, as described above, the charge transporting block copolymer according to the present invention is also effective as the binder resin for the charge generating layer.

The compounding 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 1/1. When the compounding ratio of the charge generating material to the binder resin is higher than the above range, dark attenuation increases, and it becomes difficult to obtain a uniform film by the wet coating method. On the other hand, if it is less than the above range, problems such as deterioration of photosensitivity and increase of residual potential occur. The thickness of the charge generation layer used in the present invention is generally 0.05
-5 μm is suitable, preferably 0.1-2.0 μm
It is set to the range of. As a coating method, a usual method such as a blade coating method, a ring 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 can be used.

When the uniform charge transport layer is provided, the uniform charge transport layer can be selected from any of those used as the charge transport layer of the J-shaped laminated photoreceptor in the art. For example, a benzidine-based compound, an amine-based compound, a hydrazone-based compound, a stilbene-based compound, a carbazole-based compound or the like may be used alone or in combination of two or more, and an insulating resin (for example, polycarbonate, polyarylate, polyester, polysulfone, A solid solution film in which molecules are uniformly dispersed in polyalkylmethacrylate etc. is used. Alternatively, it is possible to use a polymer compound or the like which itself has a charge transporting ability. In addition, selenium, a-Si, a-Si
An inorganic substance having a charge transporting ability such as C can also be used. As the polymer compound having a charge transporting ability, a polymer compound having a group having a charge transporting ability such as polyvinylcarbazole in a side chain, and a charge transporting ability as disclosed in JP-A-5-232727 and the like can be used. Examples thereof include a polymer compound containing the group shown in the main chain and polysilane.

As the uniform charge transport layer in the S-shaped photosensitive material of the present invention, it is preferable to use a charge transporting polymer compound particularly in production. That is, when a non-uniform charge transport layer and a uniform charge transport layer are laminated to form a film, if a charge transporting low molecular weight compound is used for the uniform charge transporting layer, the charge transporting low molecular weight compound is mixed into the non-uniform charge transporting layer. As a result, the electrical insulation of the electrically inactive matrix of the heterogeneous charge transport layer is lowered against the main charges, impairing the S-shaped property, or the charge transporting low-molecular compound mixed in the heterogeneous charge transport layer is undesired. It becomes a charge trap in the uniform charge transport layer, and causes problems such as an increase in residual potential, a decrease in transportability and a decrease in photosensitivity. This problem becomes particularly noticeable when a film is formed by a wet coating method (of course, a coating solvent for the upper layer is selected that does not easily dissolve and swell the lower layer, or a heterogeneous charge transport layer is crosslinkable and curable). It is possible to avoid this problem by, for example, preventing dissolution and swelling by the upper layer coating solvent). However, as described above, it is known that it is common for polymers to undergo phase separation without being compatible with each other,
When a charge-transporting polymer compound is used as the uniform charge-transporting layer, it causes phase separation without compatibility with the heterogeneous charge-transporting layer resin, so the above-mentioned problem of mixing hardly occurs.
This has the advantage that the restrictions in selecting materials and manufacturing methods are eliminated.

Further, as the charge-transporting polymer compound for the uniform charge-transporting layer, a charge-transporting resin containing as a repeating unit at least one kind of the structure represented by the above general formula (2) or (3), It is particularly preferable because it has a high charge transporting ability and excellent mechanical properties. In particular, when a charge transporting polymer having the same structure as the charge transporting block of the block copolymer used for the nonuniform charge transporting layer is used for the uniform charge transporting layer, the charge from the nonuniform charge transporting layer to the uniform charge transporting layer is increased. The injection is particularly smooth and is particularly preferable.

Incidentally, an electrically inactive region surrounded by the charge transporting matrix may be present in the uniform charge transporting layer. For example, insulating particles having a low surface energy may be contained for the purpose of reducing the surface frictional force, abrasion, or reducing the adhesion of foreign matter to the surface. Further, charge transporting fine particles or the like may be added to the uniform charge transporting layer for the purpose of improving charge transporting ability.

A charge-transporting block copolymer in which the charge-transporting raw block and the insulating block are compatible can also be effectively used as the uniform charge-transporting layer. Furthermore, as described above, since the electrically inactive region surrounded by the charge transporting matrix may exist in the uniform charge transporting layer, the charge transporting block serves as a matrix and the insulating block serves as a domain. A charge transporting block copolymer having a micro phase separation state can also be used as the uniform charge transporting layer.

In the constitution in which the uniform charge transport layer is the outermost layer, a crosslinkable curable material is used from the viewpoint of mechanical strength,
It is preferable to use the uniform charge transport layer formed.

The uniform charge transport layer used in the present invention comprises one layer or a plurality of layers, and the total film thickness thereof is set to 50 μm or less, preferably 30 μm or less. As a coating method, a usual method such as a blade coating method, a ring 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 can be used. Further, those capable of forming a vapor phase film such as selenium and a-Si can be directly formed by a vacuum vapor deposition method or the like. In the present invention, the total thickness of the entire charge transport layer including the nonuniform charge transport layer and the uniform charge transport layer is appropriately 5 to 50 μm, preferably 10 to 40 μm.
It is set in the range of μm.

When the charge transport layer is present between the charge generation layer and the exposure light source, it is desirable that the charge transport layer is practically transparent to light of the exposure wavelength in order to prevent reduction in effective photosensitivity. Preferably, the transmittance of light used for exposure in the charge transport layer is 50% or more. It is more preferably 70% or more, and further preferably 90% or more. However, if use with low sensitivity is desired, a substance that absorbs light having an exposure wavelength can be added to adjust the effective photosensitivity.

In the present invention, the protective layer, which may be provided on the photosensitive layer as the case requires, is ozone or oxidizing gas generated from the charging member, chemical stress such as ultraviolet light, or a developer. It is effective for protecting the photosensitive layer from mechanical stress caused by contact with paper, cleaning member, etc., and improving the actual life of the photosensitive layer. In particular, the effect is remarkable when the charge generation region is provided in the uppermost layer as in the single-layer type photoconductor and the laminated type photoconductors shown in FIGS.

The protective layer is formed by containing a conductive material in a suitable binder resin. Examples of the conductive material include a metallocene compound such as dimethylferrocene, antimony oxide, tin oxide, titanium oxide, indium oxide, and ITO.
Materials such as metal oxides can be used. As the binder resin, known resins such as polyamide, urethane resin, polyester, polycarbonate, polystyrene, polyacrylamide, silicone resin, melamine resin, phenol resin and epoxy resin can be used. A semiconductive inorganic film such as amorphous carbon can also be used as the protective layer.

When using these resistance control type protective layers
Has an electric resistance of 10⁹-10 ¹⁴Within Ω · cm
Need to be in. If the electrical resistance exceeds this range
Then, the residual potential increases, while if it falls below this range, the residual potential increases.
Charge leakage in the plane direction can no longer be ignored, resulting in lower resolution
Will occur.

The thickness of the protective layer is suitably 0.5 to 20 μm, preferably 1 to 10 μm.

When the protective layer is provided, a blocking layer for preventing the leakage of charges from the protective layer to the photosensitive layer can be provided between the photosensitive layers, if necessary. As the blocking layer, a known layer can be used as in the case of the protective layer.

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

As the antioxidant, known compounds can be used, for example, hindered phenols, hindered amines, phenylenediamines, hydroquinones, spirochromans, spiroindanones, organic sulfur compounds, organic phosphorus compounds. Etc.

As the light stabilizer, known compounds can be used, and examples thereof include benzophenone, benzotriazole, dithiocarbamate, tetramethylpiperidine and their derivatives, or the photoexcited state is deactivated by energy transfer or charge transfer. Examples thereof include electron withdrawing compounds and electron donating compounds.

Further, reduction of surface wear, improvement of transferability,
For the purpose of improving the cleaning property, low surface energy insulating particles such as fluororesin may be dispersed in the outermost surface layer.

The electrophotographic apparatus on which the electrophotographic photosensitive member of the present invention is mounted may be of any type as long as it uses an electrophotographic method, but in particular, an electrophotographic apparatus which performs exposure based on a digitally processed image signal. Is preferred. An electrophotographic device that performs exposure based on a digitally processed image signal is an electrophotographic device that uses a light source such as a laser or an LED to perform exposure with multi-valued light that has been binarized or pulse width modulated or intensity modulated. The apparatus is an LED printer, a laser printer, a laser exposure type digital copying machine, or the like.

E _50% / E _{10% of the} electrophotographic photoconductors listed
The value is preferably 5 or less, and more preferably the E _50% / E _10% value is less than 3 in order to exhibit preferable digital characteristics. More preferably, the value is less than 2.

For the purpose of initializing the photosensitive member after development or stabilizing the electrophotographic characteristics, a light source can be used in combination with the exposure light source for image formation. It may or may not be absorbed by the nonuniform charge transport layer, but it is preferable that light reaches at least the charge generation layer.

FIG. 7 shows a schematic structure of a laser printer 10 as an example of the electrophotographic apparatus of the present invention. This laser printer 10 is provided with a cylindrical photosensitive drum 12 as an electrophotographic photosensitive member of the present invention, and a light source for pre-exposure for removing residual charges of the photosensitive drum 12 around the photosensitive drum 12. (Red LED) 14, charging scorotron 1 for charging the photoconductor drum 12
6, an exposure laser optical system 18 that exposes the photosensitive drum 12 based on an image signal, a developing device 20 that attaches toner to an electrostatic latent image formed on the photosensitive drum 12, a toner image on the photosensitive drum 12. A transfer corotron 24 for transferring the toner to the paper 22 and a cleaning blade 26 for removing the toner remaining on the photosensitive drum 12 are arranged in this order.

The exposure laser optical system 18 is a laser diode (for example, an emission wavelength of 780 nm) that emits a laser beam based on a digitally processed image signal, a polygon mirror that deflects the emitted laser beam, and a laser beam of a predetermined size. A lens system for moving at a constant speed is provided.

[0133]

EXAMPLES 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 make modifications to the following examples based on the known knowledge of synthetic chemistry and electrophotography. (Synthesis Example 1) Synthesis of an asymmetric azo type polymerization initiator having one reactive functional group 12.5 g of 4-aminobenzoic acid was dissolved in a hydrochloric acid aqueous solution consisting of 200 ml of water and 30 ml of 35% hydrochloric acid at 0 ° C. , And 120 g of ice was added. This was added dropwise to 100 ml of water in which 6.5 g of sodium nitrite was dissolved under ice cooling. Further, this was cooled under ice-cooling with sodium acetate 9
0 g, methylmalononitrile (methyldicyanomethyl)
It was added dropwise to a solution consisting of 7.5 g, 120 ml of ethanol and 200 ml of water. After stirring for 1 hour at 0 ° C, 20
The temperature was raised to 0 ° C. and the mixture was further stirred for 45 minutes. 35% here
Hydrochloric acid and diethyl ether were added to separate into an organic phase and an aqueous phase,
The organic phase was isolated. The organic phase is washed with water, dried over magnesium sulphate, evaporated to remove the solvent and dried under vacuum, giving 8.3 g of (4-carboxyphenylazo) -methylmalononitrile (methyldicyanomethyl). Obtained.

7.5 g of the above-mentioned (4-carboxyphenylazo) -methylmalononitrile was dissolved in 250 ml of toluene, and 7 g of phosphorus pentachloride dissolved in 10 ml of methylene chloride was added dropwise thereto under ice cooling. After stirring at 0 ° C. for 10 minutes, the temperature was raised to 20 ° C. and stirring was continued for 3 days. To this, 1000 ml of hexane was added, and the mixture was left overnight at 20 ° C. to crystallize the product. The crystallized product is filtered off, dried under vacuum,
4.8 g of (4-chlorinated carbonylphenylazo) -methylmalononitrile, which is an azo type polymerization initiator having one chlorinated carbonyl group as a reactive functional group, was obtained. (Synthesis Example 2) Synthesis of charge transporting polymer having reactive functional groups at both ends N, N'-bis (p, m-dimethylphenyl) -N,
N′-bis [p- (2-methoxycarbonylethyl) phenyl]-[3,3′-dimethyl-1,1′-biphenyl] -4,4′-diamine 100 g, ethylene glycol 200 g and tetrabutoxy titanium 5 g were added. The mixture was heated under reflux under a nitrogen stream for 3 hours to give N, N'-bis (p, m-dimethylphenyl) -N, N'-bis [p- (2-methoxycarbonylethyl) phenyl]-[3,3 '. The methoxy groups at both ends of -dimethyl-1,1'-biphenyl] -4,4'-diamine were replaced with 2-hydroxyethoxy groups. This was heated to 230 ° C. while reducing the pressure to 0.5 mmHg or less and distilling off ethylene glycol to carry out a polycondensation reaction with deethylene glycol for 5 hours. Then, cool to room temperature, add methylene chloride to dissolve insolubles,
By reprecipitation from acetone, 90 g of a charge-transporting polyester having hydroxy groups at both ends as reactive functional groups was obtained. The weight average molecular weight of the obtained charge transporting polyester was 75,000 (in terms of polystyrene). The molecular weight of the polyester can be controlled by the reaction temperature, the reaction temperature, etc.
It was possible to synthesize a polymer having an arbitrary molecular weight in the range of 00000. (Example 1) Weight average molecular weight 750 obtained in Synthesis Example 2
Of the charge-transporting polymer having hydroxy groups at both ends of 00 and 0.5 g of triethylamine in 120 m of toluene
A solution of 3.4 g of the azo type polymerization initiator having one chlorinated carbonyl group obtained in Synthesis Example 1 dissolved in 80 g of tetrahydrofuran was added dropwise thereto at room temperature. Then, the mixture was reacted at 25 ° C for 20 hours. The reaction product was purified by reprecipitation with toluene / methanol three times to obtain 29 g of a charge transporting polymer having azo type polymerization initiation groups at both ends.

Next, 5.0 g of the charge-transporting polymer having azo type polymerization initiation groups at both ends and 4.2 g of tert-butyl methacrylate were dissolved in 80 ml of toluene and the mixture was dried at 65 ° C. under a dry nitrogen stream. And reacted for 100 hours. The reaction product is purified by performing reprecipitation operation with toluene / methanol three times to obtain 7.6 g of a charge-transporting triblock copolymer and / or diblock copolymer represented by the following structural formula (1). It was

[0136]

[Chemical 13]

[0137] The obtained charge transporting block copolymer ¹
From the integral ratio of peaks corresponding to protons specific to each block in the 1 H-NMR spectrum, the weight composition ratio of the charge transporting block and the insulating block was about 3: 2. If this block copolymer is a block copolymer, the weight average molecular weight of each insulating block is calculated to be about 25,000 from the composition ratio and the weight average molecular weight of 75,000 of the charge transporting polymer used.

Even if the obtained product was extracted with n-hexane, which is a good solvent for poly (tert-butyl methacrylate) and a poor solvent for the triblock copolymer, poly (tert-butyl methacrylate) was used. -Butyl methacrylate) was not extracted, and it was confirmed that poly (tert-butyl methacrylate) was not produced as a by-product in this production method.

When the blend of the charge transporting polymer obtained in Synthesis Example 2 and poly (tert-butylmethacrylate) was formed from a toluene solution, a white turbid film was obtained. It was confirmed that (tert-butylmethacrylate) was incompatible, and that a simple blend of the two had a macrophase separation structure on the scale of visible wavelength or longer.

On the other hand, when the block copolymer produced in this Example was formed into a film from a toluene solution, a transparent film was obtained. However, as described above, each constituent block is incompatible, It is presumed that it has a microphase-separated structure of the following scale. (Comparative Example 1) Instead of the asymmetric azo initiator having one chlorinated carbonyl group obtained in Synthesis Example 1, 4,4'-azobis (4-) which is a symmetrical azo initiator having two chlorinated carbonyl groups. A block copolymer was produced in the same manner as in Example 1 except that cyanopentanoic acid chloride) was used.

In the reaction of the charge-transporting polymer having hydroxy groups at both ends with 4,4'-azobis (4-cyanopentanoic acid chloride), a remarkable increase in viscosity occurs, which may cause a synthetic operation such as stopping the stirrer. Caused a problem. this is,
4,4'-azobis (4-cyanopentanoic acid chloride)
Has two reactive functional groups, so as described above, P
It is presumed that a high molecular weight substance of -IP and (PI) n type was by-produced.

When the final product was extracted with n-hexane, a large amount of poly (tert-butyl methacrylate) was extracted. In this comparative example, poly (tert-butyl methacrylate) was produced as a by-product. Was confirmed. This is because, since 4,4′-azobis (4-cyanopentanoic acid chloride) has a symmetrical structure, the two radicals produced by denitrification have the same polymerization initiation ability as described above, and thus I-P-I From this, it is presumed that the homopolymer was produced at the same time as the block copolymer. From the ¹ H-NMR spectrum of the extraction residue, the weight composition ratio of the charge transporting block and the insulating block of the block copolymer was calculated to be about 3: 1. Compared to Example 1, the abundance ratio of the insulating block was almost halved, and it can be seen that in this comparative example, an insulating monomer substantially equivalent to that incorporated in the block copolymer was homopolymerized. (Example 2) On an aluminum substrate, 15 parts by weight of a zirconium alkoxide compound (Organix ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.) and a silane coupling agent (A11).
10, manufactured by Nippon Unicar Co., Ltd.) 1 part by weight, polyvinyl butyral resin (S-REC BM-S, manufactured by Shin-Etsu Chemical Co., Ltd.) 1
Parts by weight, 15 parts by weight of isopropanol, and 15 parts by weight of n-butanol are applied by a dip coating method, humidified for 10 minutes under conditions of 50 ° C. and 85% RH, and further heated for 15 minutes at 160 ° C. Then, an undercoat layer having a film thickness of 0.8 μm was formed.

Next, in the X-ray diffraction spectrum using CuKα as the radiation source, at least the Bragg angle (2θ ± 0.2
°), 7.4 °, 16.6 °, 25.5 °, and 2
4 parts by weight of chlorogallium phthalocyanine microcrystals having a strong diffraction peak at 8.3 ° were added to vinyl chloride-vinyl acetate copolymer (UCAR solution vinyl resin VMC
H, Union Carbide) 2 parts by weight, xylene 67
Parts by weight, and 33 parts by weight of n-butyl acetate, and treated with glass beads for 5 hours by a paint shake method to disperse, and then the obtained coating liquid is applied on the undercoat layer by a dip coating method, It was heated and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

Then, a solution prepared by dissolving 10 parts by weight of the copolymer obtained in Example 1 in 90 parts by weight of toluene was applied on the charge generation layer by a blade coating method,
It was heated and dried at 135 ° C. for 10 minutes to form an S-shaped charge transport layer having a film thickness of 3 μm.

Next, a coating solution prepared by dissolving 20 parts by weight of a compound comprising a repeating unit represented by the following structural formula (2) having a weight average molecular weight of 40,000, which is a charge transporting polymer, in 80 parts by weight of chlorobenzene was added to the above S. It was coated on the charge transporting layer by the blade coating method and dried by heating at 135 ° C. for 1 hour to form a uniform charge transporting layer having a film thickness of 20 μm. Thus, an electrophotographic photoreceptor having the layer structure shown in FIG. 4 was prepared. .

[0146]

[Chemical 14]

An electrostatic copying paper test apparatus (electrostatic analyzer EPA-8100, manufactured by Kawaguchi Electric Co., Ltd.) was used for the electrophotographic photoreceptor thus obtained.
Under normal temperature and humidity (20 ° C, 40% RH) environment,
The electrophotographic characteristics were evaluated. After adjusting the corona discharge voltage and charging the photoreceptor surface to -750V, adjust the halogen lamp light monochromatic to 780 nm through the interference filter so that the light intensity is 10 mW / m ² on the photoreceptor surface. When irradiated for 5 seconds, it showed an S-shaped photo-induced potential decay as shown in FIG. E _50% / E _10% value is 1.7,
The E _50% value was 10 mJ / m ² , and the residual potential was 25V. (Example 3) In an X-ray diffraction spectrum using CuKα as a radiation source, at least the Bragg angle (2θ ± 0.2
°), 8.3 °, 13.7 ° and 28.3 °, and 4 parts by weight of dichlorotin phthalocyanine microcrystals having a strong diffraction peak are added to polyvinyl butyral resin (S-Rex BM-
S, Sekisui Chemical Co., Ltd.) 2 parts by weight and chlorobenzene 10
After mixing with 0 part by weight and treating with glass beads by a paint shake method for 5 hours to disperse, the obtained dispersion is applied on an aluminum substrate by a dip coating method, and 1
Heat dried at 00 ° C for 10 minutes, film thickness 1.0 μm
The charge generation layer of was formed.

Next, a solution prepared by dissolving 20 parts by weight of the block copolymer obtained in Example 1 in 80 parts by weight of toluene was applied on the charge generation layer by a dip coating method, and then at 135 ° C. Heat-dry for 60 minutes, film thickness 20μ
An m-shaped S-shaped charge transport layer was formed to prepare an electrophotographic photoreceptor having the layer structure shown in FIG.

Electrophotographic photosensitive member thus obtained
Was evaluated in the same manner as in Example 2, and
The potential decay characteristic is a residual potential of 10 V, E_50%Value is 18mJ
/ M ², E_50%/ E_Ten%It was S-shaped with a value of 2.0. (Comparative Example 2) Instead of the block copolymer produced in Example 1,
The block copolymer prepared in Comparative Example 1 (n-hexa
Insulating homopolymer is mixed even if extraction with
Electrophotography was carried out in the same manner as in Example 2 except that
A photoconductor for use was prepared.

The electrophotographic characteristics of the electrophotographic photosensitive member thus obtained were evaluated in the same manner as in Example 2. As a result, only 8% of the photoinduced potential decay was shown. This is because the mixed insulating homopolymers segregate at the interface between the charge generation layer and the S-shaped charge transport layer and / or at the interface between the S-shaped charge transport layer and the uniform charge transport layer during macro-phase separation segregation during coating. As a result, an insulating film was formed at the interface, and the charge injection property at the interface was reduced. (Comparative Example 3) Except that the S-shaped charge transport layer was not provided,
An electrophotographic photoreceptor was prepared in the same manner as in Example 2.

The electrophotographic characteristics of the electrophotographic photosensitive member thus obtained were evaluated in the same manner as in Example 2. The E _50% value was 7 mJ / m ² , the residual potential was 20 V, and E
It was J-shaped with a _50% / E _10% value of 5.1. (Example 4) An electrophotographic photoconductor was prepared in the same manner as in Example 2 except that an aluminum drum whose surface was roughened by honing was used instead of the aluminum substrate, and a laser printer (Laser Press) was used.
4105, manufactured by Fuji Xerox Co., Ltd.) and a printing test was conducted. At this time, an ND filter was inserted in the optical path of the laser light in order to obtain the optimum exposure amount. The image quality rating is 1
For the print sample after continuous printing on the first and 2000 sheets,
It was visually observed. (Comparative Example 4) An electrophotographic photoreceptor was prepared in the same manner as in Comparative Example 3 except that an aluminum drum having a surface roughened by honing was used instead of the aluminum substrate, and the same procedure as in Example 4 was performed. A printing test was conducted.

When the print qualities obtained in Example 4 and Comparative Example 4 were compared, the print quality of Example 4 was superior in terms of reproducibility of fine lines and sharpness.

Furthermore, the first and 200th sheets in the fourth embodiment
The print quality of the 0th sheet is the same, and the electrophotographic photosensitive member of the present invention has high durability.

[0154]

INDUSTRIAL APPLICABILITY The method for producing a charge-transporting block copolymer of the present invention has broad applicability and is suitable for an electrophotographic photoreceptor having high performance and durability, particularly an S-shaped electrophotographic photoreceptor. The excellent effect that the charge-transporting block copolymer as the charge-transporting material can be produced at low cost and in high purity.

Further, the function-separated laminated type photoreceptor having the non-uniform charge transport layer containing the phase-separable charge-transportable block copolymer produced by the production method of the present invention exhibits excellent S-characteristics. The digital electrophotographic device used provides excellent print quality as well as image quality.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between an exposure amount and a surface potential of 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 schematic sectional view showing an example of an electrophotographic photoreceptor according to the present invention.

FIG. 4 is a schematic cross-sectional view showing another example of the electrophotographic photoreceptor according to the present invention.

FIG. 5 is a schematic cross-sectional view showing another example of the electrophotographic photosensitive member according to the present invention.

FIG. 6 is a schematic cross-sectional view showing another example of the electrophotographic photosensitive member according to the present invention.

FIG. 7 is a schematic configuration diagram of an electrophotographic apparatus in which the electrophotographic photosensitive member according to the present invention is mounted and which forms an image based on a digitally processed image signal.

[Explanation of symbols]

1 Conductive support 2 Charge generation layer 3 Non-uniform charge transport layer (S-shaped charge transport layer) 4 Uniform charge transport layer 5 Charge transport layer 10 laser printer 12 Photosensitive drum 14 Pre-exposure light source 16 Scorotron for charging 18 Laser optical system for exposure 20 Developer 22 sheets 24 Corotron for transfer 26 Cleaning blade

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taketoshi Higashi 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor, Yasushi Sakaguchi 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Taketoshi Hoshizaki 1600 Takematsu, Minamiashigara City, Kanagawa Fuji Xerox Co., Ltd. (56) Reference JP 10-182760 (JP, A) JP 9-302196 (JP, A) JP 4-39315 (JP, A) JP-A-3-139551 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08F 293/00

Claims (9)

(57) [Claims] 1. A method for producing a charge-transporting block copolymer containing a charge-transporting block and an insulating block, comprising:
From a charge transporting polymer having a reactive functional group at the terminal and a low molecular weight polymerization initiator having an asymmetric structure having one functional group capable of reacting with the functional group, the charge transporting property having a polymerization initiating group at the terminal is increased. A method for producing a charge-transporting block copolymer, which comprises obtaining a molecular initiator and polymerizing an insulating monomer from the polymeric initiator. 2. The method for producing a charge transporting block copolymer according to claim 1, wherein the low molecular weight polymerization initiator is an asymmetric azo compound represented by the following general formula (1). [Chemical 1] (In the formula, L represents a divalent hydrocarbon group or a hetero atom-containing hydrocarbon group which may have a branched or ring structure,
X is a functional group capable of reacting with a functional group at the terminal of the charge transporting polymer, and is a hydroxy group, a carboxyl group, a carbonyl halide group, an amino group, an epoxy group, an isocyanate group, a melamine group, a phenol group, a methyl halide. A group selected from the group consisting of a group, an alkoxysilyl group and an alkoxycarbonyl group, and Y represents a monovalent heteroatom-containing hydrocarbon group selected from the group consisting of the following partial structural formula (1); 2] In the formula, R ^{1 to} R ¹¹ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxycarbonyl group. Represents a substituted or unsubstituted acyl group or a substituted or unsubstituted acyloxy group. ) 3. The method for producing a charge-transporting block copolymer according to claim 2, wherein X in the general formula (1) is a carbonyl halide group. 4. The method for producing a charge-transporting block copolymer according to claim 2, wherein L in the general formula (1) is a substituted or unsubstituted arylene group. 5. The method for producing a charge-transporting block copolymer according to claim 2, wherein Y in the general formula (1) is an alkyldicyanomethyl group. 6. The method for producing a charge transporting block copolymer according to claim 2, wherein the asymmetric azo compound is (halogenated carbonylphenylazo) -alkyldicyanomethyl. 7. The charge transporting property according to claim 1, wherein the charge transporting block contains at least one structure represented by the following general formula (2) or (3) as a repeating unit. A method for producing a block copolymer. [Chemical 3] (In the formula, Ar ¹ and Ar ² each independently represent a substituted or unsubstituted aryl group, X ¹ represents a divalent hydrocarbon group having an aromatic ring structure or a hetero atom-containing hydrocarbon group, X ² And X ³ each independently represent a substituted or unsubstituted arylene group, L ¹ represents a divalent hydrocarbon group which may have a branched or ring structure or a hetero atom-containing hydrocarbon group, and m and n are , Each represents an integer selected from 0 or 1.) (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 hetero atom-containing hydrocarbon group.) 8. The method for producing a charge-transporting block copolymer according to claim 7, wherein X ¹ in the general formula (2) is a substituted or unsubstituted biphenylene group. 9. The insulating monomer is represented by the following general formula (4):
The method for producing a charge-transporting block copolymer according to any one of claims 1, 2 and 7, which comprises at least one compound represented by [Chemical 5] (In the formula, R ^{1 to} R ³ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁴ represents a halogen atom, a substituted or unsubstituted alkyl group. Represents a group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted acyl group, a substituted or unsubstituted acyloxy group, or a substituted or unsubstituted alkoxycarbonyl group.)