JP2001305774A - Electrophotographic photoreceptor and process cartridge and electrophotographic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor excellent in wear resistance for repeated use and having little residual potential, and to provide a process cartridge and an electrophotographic device using the photoreceptor. SOLUTION: In the electrophotographic photoreceptor having a photosensitive layer 2 and a protective layer 6 formed on a conductive body 1, the protective layer 6 contains at least conductive particles and a copolymer containing charge transfer blocks and insulating blocks. The wear resistance for repeated use is improved and the residual potential is decreased in the electrophotographic photoreceptor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member having a surface protective layer having excellent abrasion resistance, and a process cartridge and an electrophotographic apparatus using the same.

[0002]

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

As an electrophotographic photoreceptor used in the electrophotographic technology, one using an inorganic photoconductive material such as selenium, a selenium-tellurium alloy, or a selenium-arsenic alloy has been widely known. On the other hand, research on electrophotographic photoreceptors using organic photoconductive materials, which have advantages in terms of cost, manufacturability, disposability, etc., compared with these inorganic photoreceptors, has also become active. It has surpassed the body. In addition to a single-layer type photoreceptor in which phthalocyanine-based compounds are dispersed as a charge-generating material in a resin, a function-separated type lamination structure in which photocharge generation and charge transport, which are the elementary processes of photoconduction, are carried out in separate layers, respectively. With the development of such a device, the degree of freedom in material selection has been increased, and the performance has been remarkably improved. At present, this function-separated and laminated organic photoreceptor has become the mainstream of the electrophotographic photoreceptor. The charge generation layer for the function-separated laminated organic photoreceptor is formed by directly depositing a pigment having a charge generation ability such as a quinone pigment, a perylene pigment, an azo pigment, a phthalocyanine pigment, or selenium by vapor deposition or the like. Alternatively, those having a high concentration dispersed in a binder resin have been put to practical use. On the other hand, as the charge transport layer, a material in which a low-molecular compound having a charge transport ability such as a hydrazone compound, a benzidine compound, an amine compound, or a stilbene compound is molecularly dispersed in an insulating resin is used.

[0004] The durability required for electrophotographic photoreceptors is becoming severer year by year. In order to solve the problems such as abrasion and scratches on the surface layer due to repeated use, it is necessary to study techniques necessary for improving the durability. Continued. In response to these requirements, many studies have been made on surface protective layers. However, if the surface protective layer is composed of only a cross-linkable curable resin, the surface protective layer becomes an insulating layer, and the photoelectric characteristics of the photoconductor are sacrificed. Specifically, the problem that the development potential margin is narrowed due to an increase in the light portion potential at the time of exposure, and the residual potential after static elimination is increased, especially when long-term repeated printing is performed, image density is reduced. There was a problem of lowering.

As a method for improving the photoelectric characteristics, there has been reported a method of dispersing a conductive metal oxide fine powder in a surface protective layer as a resistance control material (JP-A-57-12834).
No. 4). The decrease in the photoelectric characteristics of the photoreceptor by this method is small, and the above-mentioned problems are remarkably improved. But,
Generally, there is a problem that the resistance value of the metal oxide used as the conductive fine powder largely depends on the humidity of the environment. For this reason, there is an essential problem that the surface resistance of the photoreceptor is reduced particularly under high temperature and high humidity, and the image quality is greatly reduced due to blurring of the electrostatic latent image.

As another method for improving the photoelectric characteristics, a method has been reported in which a charge transporting material is dispersed in a binder resin, and then the binder resin is cured to form a surface protective layer (Japanese Patent Laid-Open No. 4-15659). No.). In this method, the surface resistance of the photoreceptor did not depend on humidity, and there was no problem of image quality. However, the addition of a low-molecular-weight component such as a charge-transporting substance inhibits the curing reaction and lowers the mechanical strength of the surface protective layer. Therefore, even when a cross-linking curable resin having high mechanical strength is used alone, the mechanical strength of the surface protective layer is greatly reduced by adding a low-molecular component such as a charge transport material essential for improving photoelectric properties. .

On the other hand, it has been proposed to crosslink a charge-transporting polymer compound to make the molecular structure three-dimensional and to cure it (Japanese Patent Laid-Open No. 6-250423). In this method, although the reduction in mechanical strength due to the inhibition of the curing reaction by the low molecular weight compound is eliminated, the cross-linking site exists at the site directly bonded to the charge transporting site, and therefore, the cross-linking site (or the reaction cannot be performed) Uncrosslinked sites) adversely affect the charge transport site, causing problems such as an increase in residual potential, a decrease in responsiveness due to a decrease in charge transport ability, and a decrease in the repetition stability of electrical characteristics.

[0008] In order to solve these problems, the present inventors have proposed, as a charge transporting material, a copolymer containing a charge transporting block and an insulating block, which are phase-separated into a charge transporting phase and an insulating phase. (Japanese Patent Laid-Open No. 11-65).
No. 152). In this method, by cross-linking the charge transport site and the cross-linking site spatially by copolymerizing the cross-linking site with the insulating block, the adverse effect of the cross-linking site on the charge transport site can be reduced, and the electrical characteristics can be reduced. The above problem could be reduced. However, further improvement has been demanded from the viewpoint of wear resistance.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances in the prior art, and is an electrophotographic photoreceptor having excellent abrasion resistance when used repeatedly and having a low residual potential. It is another object of the present invention to provide a process cartridge and an electrophotographic apparatus using the same.

[0010]

Means for Solving the Problems The present inventors have made intensive studies to further improve the abrasion resistance of a protective layer containing a copolymer comprising a charge transport block and an insulating block.
By dispersing conductive particles in a copolymer containing a charge transport block and an insulating block, the surface protective layer has excellent overall properties that balance electrical properties and abrasion resistance. It has been found that the present invention is suitable, and the present invention has been completed.

That is, an object of the present invention is to provide an electrophotographic photosensitive member having at least a photosensitive layer and a protective layer provided on a conductive substrate, wherein the protective layer comprises at least conductive particles, a charge transport block and an insulating block. The problem is solved by providing an electrophotographic photosensitive member characterized by containing a copolymer containing the same.

Further, since the copolymer containing the charge transporting block and the insulating block has a three-dimensional molecular structure by crosslinking, further abrasion resistance can be obtained.

In particular, since the cross-linking site in the copolymer exists in the insulating block, the electric characteristics are improved.

[0014] Further, since the copolymer containing the charge transporting block and the insulating block is phase-separated into a phase composed of the charge transporting block and a phase composed of the insulating block, the electric characteristics are improved. .

[0015] Further, the charge transporting block is at least contained in the repeating unit of the charge transporting block in the copolymer containing the charge transporting block and the insulating block, so that the charge transporting block has a triarylamine structure. A photoreceptor having excellent properties can be provided.

Further, the process cartridge of the present invention has at least one selected from the group consisting of the above-mentioned electrophotographic photosensitive member having excellent charge transporting ability and excellent mechanical properties, and a charging means, a developing means, a cleaning means, and a discharging means. By having one unit integrally and being detachable from the main body of the electrophotographic apparatus, the image density is excellent in repetition stability and reliability.

The electrophotographic apparatus of the present invention also has an electrophotographic photosensitive member having excellent charge transporting ability and mechanical properties, a charging means for charging the electrophotographic photosensitive member, and an electrophotographic photosensitive member charged by the charging means. The image density repetition stability by including an exposure unit for exposing the body, a development unit for developing the portion exposed by the exposure unit, and a transfer unit for transferring an image developed on the electrophotographic photosensitive member by the development unit And excellent reliability.

In the following, a “copolymer having a charge transporting block and an insulating block whose molecular structure is made three-dimensional by cross-linking” is referred to as a “cross-linked copolymer”.
The term "copolymer having a crosslinkable functional group, including a charge transporting block and an insulating block" is referred to as a "copolymer having a crosslinkable functional group", and the term "copolymer having a crosslinkable functional group," A copolymer containing a functional block and an insulating block, which has not yet been crosslinked, may be abbreviated as "a copolymer before crosslinking."

The term “insulating property” as used herein means that the transport energy level is largely different from the transport energy level of the main transport charge, and at a normal electric field strength, the transport charge is substantially not injected, and the main transport charge is not substantially injected. It means that the electric charge is in a practically electrically insulating state.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each layer constituting the electrophotographic photosensitive member of the present invention will be described in more detail. The photosensitive layer may be a single layer type in which a charge generating substance is dispersed and contained in a resin, or may be a stacked type including a charge generating layer and a charge transporting layer. Further, the charge transport layer may be two or more layers.

An example of the electrophotographic photosensitive member of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 are schematic views showing a cross section of the electrophotographic photosensitive member of the present invention. FIG. 1 shows an example of a single-layer type in which a photosensitive layer 2 and a protective layer 6 are provided on a conductive support 1. FIG. 2 shows the photoreceptor of FIG. 1 in which an undercoat layer 3 is further provided between the conductive support 1 and the photosensitive layer 2.

FIGS. 3 and 4 are schematic views showing cross sections of an electrophotographic photosensitive member according to another embodiment of the present invention. FIG. 3 is an example of a stacked type in which a charge generation layer 4, a charge transport layer 5, and a protective layer 6 are sequentially provided on a conductive support 1. FIG.
In the photoconductor of FIG. 3, an undercoat layer 3 is further provided between the conductive support 1 and the charge generation layer 4.

These electrophotographic photoreceptors can further include a diffuse reflection layer, if desired.

Further, a blocking layer for preventing leakage of electric charge from the protective layer to the photosensitive layer can be provided between the photosensitive layer and the protective layer. As the blocking layer, a known layer can be used.

The protective layer of the present invention needs to contain at least conductive particles and a copolymer containing a charge transport block and an insulating block, and at least the conductive particles are dispersed therein. In addition, it can be obtained by applying a coating solution in which a copolymer containing a charge transport block and an insulating block is dissolved, and forming a film.

The protective layer of the present invention contains conductive particles, so that the electric charge is transferred by the conductive particles, thereby reducing the substantial dielectric film thickness of the copolymer containing the charge transport block and the insulating block. It is possible to improve the electrical characteristics. In addition, in a protective layer in which conductive particles are dispersed in an insulating resin and the charge is transferred only by the conductive particles, the characteristics are greatly affected by changes in the contact state of the conductive particles and the electrical resistance of the conductive particles. Changes, image blurring, and an increase in residual potential are likely to occur. However, since the binder resin has a charge transporting property, it is possible to transport the charge even if the conductive particles do not come into contact with each other, and no increase in the residual potential occurs. Because of the rectification, there is no occurrence of image blur caused by the charge flowing in the horizontal direction.

The binder resin used in the protective layer of the present invention has a charge transport property, and the binder resin having the charge transport property is a copolymer containing a charge transport block and an insulating block. Therefore, the mechanical strength is higher than that of the binder resin in which the low molecular weight is dispersed, and the curing reaction is not hindered. Also, rather than a binder resin consisting of a charge-transporting polymer that does not contain an insulating block, a copolymer containing a charge-transporting block and an insulating block is used. Temperature, glass transition temperature, crystallinity, refractive index, adhesion, adsorptivity, flexibility, solubility, melting, phase separation, etc. It is possible to control.

The molecular structure of the copolymer containing the charge transporting block and the insulating block does not necessarily have to be three-dimensional by cross-linking, and may not be cross-linked. It is preferable that the composition be further improved in abrasion resistance.

The crosslinking site such as a crosslinkable functional group may be present in either the charge transporting block or the insulating block, or may be present in both. Particularly, the crosslinking site in the copolymer is preferably It is preferable that only the insulating block be provided because the electric characteristics are good.

Further, since the copolymer containing the charge transporting block and the insulating block is phase-separated into a phase composed of the charge transporting block and a phase composed of the insulating block, the concentration of the charge transporting site is reduced. Without being diluted,
Good charge transport performance is maintained, and furthermore, by spatially separating the insulating block from the insulating block, it is possible to minimize the adverse effect on the charge transporting ability of the insulating block, thereby improving the electrical characteristics.

In particular, when the crosslinked portion exists only in the insulating block and is separated into the charge transporting phase and the insulating phase, the crosslinked portion and the uncrosslinked portion which cannot be crosslinked and remain are not crosslinked. By spatially separating from the charge transporting site,
It is possible to minimize the adverse effect on the charge transport performance. Therefore, it is possible to provide an electrophotographic photoreceptor which does not deteriorate the charge transporting property, is excellent in photosensitivity, residual potential, charge transporting speed, repetition stability of electrical characteristics, and is excellent in abrasion resistance. Furthermore, the degree of freedom in designing the charge transporting site and the cross-linking site is increased, and compatibility between electrophotographic characteristics and abrasion resistance can be facilitated.

Furthermore, a solution containing a block copolymer or a graft copolymer composed of a charge transport block and an insulating block, having conductive particles dispersed therein and having a crosslinkable site such as a crosslinkable functional group, is applied. Thereafter, crosslinking is carried out to form a uniform and good crosslinked polymer film.

Further, the protective layer used in the electrophotographic photoreceptor of the present invention is formed by crosslinking a copolymer having a hydroxy group and comprising a charge transporting block and an insulating block with a polyvalent isocyanate compound. It is preferable to include a substance.

Further, the protective layer used in the electrophotographic photoreceptor of the present invention contains a crosslinked polymer by a condensation reaction between functional groups in a copolymer containing a charge transporting block and an insulating block. No need to add cross-linking agent,
It is possible to eliminate the adverse effect on the charge transport property caused by the cross-linking agent remaining in the charge transport phase. For example, an alkoxysilyl group can be crosslinked by a condensation reaction between alkoxysilyl groups. Alkoxysilyl groups have moderate reactivity, which is advantageous for synthesis and handling,
The crosslinking reaction can be easily caused, and the alcohol generated by the condensation is also preferable because it does not remain in the photosensitive layer by being vaporized.

The protective layer containing the cross-linked copolymer is formed from a coating solution in which the molecular structure is not three-dimensional and before cross-linking and, if necessary, a cross-linking agent and / or a catalyst. Then, it can be obtained by performing a treatment for crosslinking as required.

Examples of the crosslinkable functional group include crosslinkable functional groups described in literatures such as Crosslinking Agent Handbook (Taiseisha, 1981) and synthesis and application of reactive polymers (CMC, 1989). Any group may be used as long as the group is a hydroxy group, an alkoxysilyl group, an epoxy group, a carboxyl group, a halogen group, an isocyanate group, a mercapto group, a chlorosulfone group, an amino group, an amide group, a tertiary amino group, Examples thereof include a nitrile group, a pyridine group, a compound having an acid anhydride structure, and a compound having a double bond. These crosslinkable functional groups may be present in either or both of the charge transport block and the insulating block, but those present only in the insulating block are formed from the charge transport block. This has little effect on the charge transporting phase, and is advantageous in electrical characteristics.

In the crosslinking reaction, a crosslinking agent and / or a catalyst and / or crosslinking conditions are provided according to the reaction. Crosslinking reactions, crosslinking agents, catalysts, and crosslinking conditions, and combinations thereof, are described in the Crosslinking Agent Handbook (Taisei,
1982), synthesis and application of reactive polymers (CMC, 1989), etc., as long as the crosslinkable functional groups are crosslinked. Examples of the crosslinking agent include a sulfur compound, an organic peroxide, a polyvalent phenol resin, a polyvalent amino resin, a polyvalent halogen compound, a polyvalent amine compound, a polyvalent azo compound, and a polyvalent isocyanate compound. And polyvalent silyl isocyanate compounds, polyvalent epoxy compounds, silane compounds, titanate compounds, polyvalent carboxylic acid compounds, acid anhydrides and the like. These crosslinkers are pre-mixed with a copolymer having a crosslinkable functional group, and then coated and cross-linked, or the copolymer is pre-coated and sprayed, immersed, or exposed to steam. Contact and crosslink.

The crosslinkable functional group is a hydroxy group,
It is particularly preferable to use a polyvalent isocyanate compound as the crosslinking agent. When the crosslinkable functional group is a hydroxy group and a polyvalent isocyanate compound is used as a crosslinking agent, a metal acetate, metal chloride, copper sulfate, di-n-butyltin dilaurate, etc. may be used as a catalyst. Can be added. Heating can be performed to promote crosslinking. As the polyvalent isocyanate compound, it is more preferable to use a derivative obtained from an isocyanate monomer or a modified polyisocyanate such as a prepolymer. Examples thereof include modified adducts obtained by adding an isocyanate to a polyol having three or more functional groups, modified burettes obtained by modifying a compound having a urea bond with an isocyanate compound, modified allophanates obtained by adding an isocyanate to a urethane group, and isocyanates Nurate modified form,
And the like, and a carbodiimide-modified product is also used. In particular, the modified burette of hexamethylene diisocyanate and the modified isocyanurate of hexamethylene diisocyanate represented by the following structural formulas (1) and (2) are advantageous in terms of mechanical strength and electrical properties. Shows particularly excellent characteristics.

[0040]

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[0041]

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Further, as another isocyanate compound,
For example, tolylene diisocyanate (TDI), diphenylmethane diisosocyanate (MDI), 1,5-naphthylene diisocyanate, tolidine diisocyanate,
1,6-hexamethylene diisocyanate, xylene diisocyanate, lysine isocyanate, tetramethyl xylene diisocyanate, 1,3,6-hexamethylene triisocyanate, lysine ester triisocyanate, 1,6,11-undecane triisocyanate,
1,8-diisocyanate-4-isocyanatomethyloctane, triphenylmethane triisocyanate, tris (isocyanatophenyl) thiophosphate,
And general isocyanate monomers. Although included in the modified polyisocyanate, a blocked isocyanate reacted with a blocking agent for temporarily masking the activity of the isocyanate group can also be preferably used. This is preferable from the viewpoint of extending the pot life of the coating liquid.

Examples of silane compounds and titanate compounds that can be used as a crosslinking agent include the following. Specific examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, and tris-
(Β-methoxyethoxy) vinylsilane, vinyltriacetoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercapto Known compounds such as propyltrimethoxysilane, β-mercaptoethyltrimethoxysilane, γ-chloropropyltrimethoxysilane, isopropyltristearoyl titanate, and isopropyl methacrylisostearoyl titanate are exemplified.

When the cross-linked copolymer is a cross-linked polymer obtained by a condensation reaction between functional groups in a copolymer containing a charge transport block and an insulating block, it is necessary to add a cross-linking agent. In addition, it is possible to eliminate the adverse effect on the charge transport property caused by the cross-linking agent remaining in the charge transport phase. In particular, when the cross-linking site exists only in the insulating block, or in the case of a copolymer having a cross-linkable functional group only in the insulating block, there is no cross-linking agent remaining in the charge transporting phase, Crosslinking sites in the charge transporting phase, and
Since there is no uncrosslinked site, the charge transporting property is not impaired, which is particularly preferable. Examples of the functional groups capable of undergoing a condensation reaction between the functional groups include alkoxysilyl groups, isocyanate groups, a hydroxyl group and an isocyanate group. In particular, the alkoxysilyl group has an appropriate reactivity, which is advantageous for synthesis and handling, and can easily cause a crosslinking reaction. It is preferable because it does not remain in When the crosslinkable functional group is an alkoxysilyl group, an acid such as acetic acid or hydrochloric acid, an alkali, an organometallic compound, or the like can be added as a catalyst, and water may be further added. Heating can be performed to promote crosslinking.

The copolymer before cross-linking used in the present invention may be in any connection form of the constituent blocks.
For example, the charge transporting block is A, and the insulating block is B
AB type, ABA type, BAB type, (AB) n type,
(AB) nA-type and B (AB) n-type block copolymers, graft copolymers having a charge-transporting block as a main chain and an insulating block as a side chain, an insulating block as a main chain, charge-transporting property A and / or A are added to a side chain of a graft copolymer having a block as a side chain or a block copolymer such as an ABA type.
Or a block copolymer grafted with B-a block copolymer such as a graft copolymer, a graft copolymer, a block-
Examples include a graft copolymer.

The crosslinkable functional group of the copolymer before crosslinking used in the present invention may be contained in both or one of the charge transport block and the insulating block. The insulating block may be formed of a block in which a repeating unit having a crosslinkable functional group is polymerized and a block in which a repeating unit having no crosslinkable functional group is polymerized. Further, the insulating block may be formed only of a block obtained by polymerizing a repeating unit having a crosslinkable functional group. In particular, the crosslinkable functional group is present only in the insulating block, and the composition ratio of the repeating unit having a crosslinkable functional group and the repeating unit having no crosslinkable functional group in the insulating block is 1:20 to A range of 10: 1 (weight ratio) is preferable, and a range of 1: 5 to 3: 1 (weight ratio) is more preferable. When the composition ratio of the repeating unit having a crosslinkable functional group exceeds the upper limit, there is a tendency to be brittle, and when the composition ratio of the repeating unit having a crosslinkable functional group is below the lower limit, mechanical strength is increased. It tends to worsen.

The copolymer before cross-linking blocks a repeating unit having a cross-linkable functional group when forming the charge transporting block or the insulating block of the copolymer containing the charge transporting block and the insulating block. During random copolymerization,
Alternatively, it can be obtained by block copolymerization. In addition, it can be obtained by polymerizing a repeating unit having a crosslinkable functional group at the terminal of a block copolymer or a graft copolymer having no charge-crosslinkable functional group and a charge transporting block and an insulating block. Can be.

As is well known in the field of polymer blends and polymer alloys, different polymers are generally incompatible with each other, and mixtures thereof and block copolymers or graft copolymers have a phase-separated state. take. Generally, in a mere mixture, that is, a polymer blend, the phase separation scale is macroscopic to several μm or more (macrophase separation). On the other hand, the block copolymer and the graft copolymer in which each component is connected by a covalent bond give a phase separation state composed of fine domains of submicron or less (microphase separation). It is known that the scale of phase separation in block copolymers and graft copolymers is generally the same dimension as the average length of each block, and is approximately proportional to the molecular weight. The copolymer containing a charge transporting block and an insulating block used in the present invention generally takes a microphase-separated state. However, copolymers containing a charge-transporting block and an insulating block do not always take a microphase-separated state, but depending on the combination of each block, some exhibit compatibility and do not cause phase separation. .

In general, the phase separation state in a phase-separable block or a graft copolymer depends on the type of constituent blocks,
The most thermodynamically stable structure exists due to the molecular weight and the composition ratio of both blocks, etc. In the copolymer consisting of A block and B block, it depends only on the A / B composition ratio, regardless of the connection type However, 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, A / B alternating layers, B is a rod-shaped domain, A is a matrix, and B is a spherical domain, A is a matrix. Changes systematically into a matrix. However, when a film is formed by a wet coating method, the phase separation state can be arbitrarily controlled depending on the solvent used, the drying speed, and the like. For example, even when the A / B ratio is large and a B sphere-A matrix is taken thermodynamically, if a solvent that is both a good solvent for B and a poor solvent for A is selected as a coating solvent, A sphere-B A matrix structure can be obtained. Also, using good solvents of both A and B,
When the solvent is rapidly removed, a phase separation structure (modulation structure) frozen in a spinodal decomposition state may be obtained. In addition, when a polymer having a high A / B ratio and having a thermodynamically B-sphere-A matrix and a polymer compatible only with B is added, the amount of B-sphere increases as the amount of addition increases. Bloated,
Eventually, A gives a phase-separated structure in which a polymer compatible with only spheres and B and B serves as a matrix.

Examples of the method for synthesizing the copolymer having a crosslinkable functional group used in the present invention include the fourth edition of Experimental Chemistry Lecture 28, Polymer Synthesis (Maruzen, 1992), Macromonomer Chemistry and Industry (IPC). , 1990), polymer compatibilization and evaluation technology (Technical Information Association, 1992), block copolymers or graft copolymers described in documents such as New Polymer One Point 12 polymer alloy (Kyoritsu, 1988). Any suitable synthetic method that can provide coalescence can be used.

For example, a desired block copolymer can be obtained by previously synthesizing a charge transporting polymer and an insulating polymer and reacting and bonding the polymers. Further, when the polymerization form of the monomer forming the charge transporting block and the monomer forming the insulating block are the same and the reactivities of both are significantly different, simply polymerizing a mixture of those monomers firstly, After the monomer having higher reactivity is polymerized and the monomer is consumed, the monomer having lower reactivity is polymerized to obtain a desired block copolymer. In addition, a polymer of one monomer is synthesized in advance, and azo, peracid ester, peroxy, dithiocarbamate,
A desired block copolymer or graft copolymer can also be obtained by introducing a polymerization initiator containing a group having a polymerization initiation ability, such as an alkali metal alcoholate or an alkali metal alkyl, and polymerizing the other monomer with the polymerization initiator. A polymer is obtained. According to this method, a block copolymer or a graft copolymer comprising a polycondensation or polyaddition polymer and an addition polymerization or ring-opening polymerization polymer can be easily obtained. In addition, azo, peracid ester,
By using a compound containing a plurality of groups having a polymerization initiation ability such as peroxy, first, one monomer is polymerized from a part of the polymerization initiation groups, and then the other monomer is polymerized from the remaining polymerization initiation groups. The desired block copolymer is also obtained. Also, a desired block copolymer can be obtained by sequentially polymerizing each monomer by a living polymerization method such as a cation living polymerization method, an anion living polymerization method, or a radical living polymerization method. The living polymerization method has an advantage that the molecular weight of each block can be easily controlled and a polymer having a narrow molecular weight distribution can be obtained. In addition, immortal polymerization method, Inifer
The desired block copolymer can also be obtained by sequentially polymerizing each monomer by a ter method or the like. Furthermore, a desired macro-copolymer can be obtained by synthesizing a macromonomer in which the other monomer has been introduced into the terminal of the polymer of one monomer in advance, and polymerizing the macromonomer.

The molecular weights of the charge transporting block and the insulating block of the copolymer of the present invention may be any values.
In order to exhibit high polymer properties, the molecular weight is desirably 2000 or more. In order to facilitate phase separation, the molecular weights of the charge transporting block and the insulating block are 2,000 or more, preferably 5,000 or more, more preferably 1,000 or more.
It is 0 or more, more preferably 20,000 or more. There is no particular limitation on the upper limit of the molecular weight in terms of electrical characteristics and mechanical characteristics.However, when a film is formed by a wet coating method, it is necessary that the upper limit of the molecular weight be within a range that gives an appropriate solution viscosity. Is preferably 5,000,000 or less.

The weight ratio between the charge transporting block and the insulating block in the copolymer of the present invention is set between 1: 9 and 9: 1. In particular, 2: 8 to 8: 2 is preferable, and 3: 7 to 7: 3 is particularly preferable. When the weight ratio of the charge transporting block is smaller than the above range, the charge transporting property cannot be sufficiently exerted, causing problems such as a decrease in photosensitivity, an increase in residual potential, and a decrease in repetition stability. Also,
When the weight ratio of the charge transporting block is larger than the above range, the mechanical strength tends to decrease.

The charge transporting block of the copolymer of the present invention may be any block such as polyvinylcarbazole or polysilane as long as it has a structure having a charge transporting property in its repeating unit. Such a compound having a triarylamine structure in its repeating unit is preferred in terms of charge mobility, charge injection property, charge life, visible light and infrared light transmittance, chemical stability and the like.

In particular, as the triarylamine structure, at least one of the structures represented by the following general formula (3) or (4)
Those containing a seed as a repeating unit are preferred.

[0056]

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[0057]

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In the above general formula (3), Ar ¹ and Ar ²
Are each independently selected from a substituted or unsubstituted aryl group, and specific examples of the aryl group include a phenyl group,
Examples include a biphenyl group, a naphthyl group, and a pyrenyl group. Examples of the substituent include a methyl group, an ethyl group, a methoxy group, and a halogen atom.

X ¹ is selected from a divalent hydrocarbon group having an aromatic ring structure or a hetero atom-containing hydrocarbon group. Specific examples include a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group, a methylenediphenyl group, a cyclohexyredenediphenyl group, an oxydiphenyl group,
Examples thereof include a thiodiphenyl group and the like, and methyl-substituted, ethyl-substituted, methoxy-substituted, and halogen-substituted forms thereof. Of these, a substituted or unsubstituted biphenylene group is particularly preferable in view of charge transportability.

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

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

[0062]

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In the above general formula (4), Ar ³ and Ar ⁴
Are each independently selected from a substituted or unsubstituted aryl group, and specific examples of the aryl group include a phenyl group,
Examples include a biphenyl group, a naphthyl group, and a pyrenyl group. Examples of the substituent include an alkyl group or an alkoxy group having 1 to 12 carbon atoms, a diphenylamino group, and a halogen atom.

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

[0065]

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[0066]

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The insulating block in the copolymer of the present invention may be any of polycarbonate, polyarylate, polyester, polysulfone, polymethyl methacrylate, polyurethane and the like.
It is preferable to be made of a polymer of a vinyl monomer in terms of flexibility, transparency of visible light and infrared light, chemical stability, insulating properties and the like.

In particular, as the vinyl monomer, a monomer obtained by polymerizing at least one vinyl monomer represented by the following general formula (5) is preferable. Further, a vinyl monomer having a crosslinkable functional group represented by the following general formula (6) and a vinyl monomer represented by the following general formula (5) obtained by copolymerizing at least one kind thereof are preferable.

[0069]

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In the general formula (5), R ^{1 to} R ³ are each independently selected from a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl or aryl group. Specific examples of the substituted or unsubstituted alkyl group or aryl group include a methyl group, an ethyl group, a methoxy group, a chloromethyl group, a phenyl group, a tolyl group, and the like.

R ⁴ is a substituted or unsubstituted alkyl group,
It is selected from an aryl group, an alkoxy group, an acyl group, an acyloxy group, or an alkoxycarbonyl group. The alkyl group, the alkoxy group, the acyl group, the acyloxy group, and the 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. Examples of the substituent include a halogen atom, a phenyl group, a hydroxy group, an amino group, an isocyanate group, an epoxy group, and an alkoxysilyl group.

[0072]

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In the above general formula (6), R ^{5 to} R ⁷ are each independently selected from a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl group or aryl group. Specific examples of the substituted or unsubstituted alkyl group or aryl group include a methyl group, an ethyl group, a methoxy group, a chloromethyl group, a phenyl group, a tolyl group, and the like.

R ⁸ is a chlorosulfone group, a carboxyl group, a hydroxy group, a mercapto group, a nitrile group, an isocyanate group, an amino group, an alkyl group substituted with an epoxy group or an alkoxysilyl group, an aryl group, an alkoxy group, an acyl group. , An acyloxy group, or an alkoxycarbonyl group.

The alkyl group may have a branched or cyclic structure, but preferably has 1 to 20 carbon atoms. Examples of the aryl group include a phenyl group, a naphthyl group and a pyrenyl group.

In the copolymer having a crosslinkable functional group of the present invention, specific examples of the structural formula represented by the above general formula (3), which is contained as a repeating unit in the charge transporting block, are shown in Tables 1 to 3 below. 4, specific examples of the structural formula represented by the above general formula (4) are shown in the following Table 5, and the above general formula (5) containing as a repeating unit in the insulating block.
Specific examples of the structural formula of the vinyl monomer represented by the following Table 6
Specific examples of the vinyl monomer having a crosslinkable functional group represented by the general formula (6) are shown in Tables 8 to 10 below, but the present invention is not limited thereto. Also,
Specific examples of the charge transporting copolymer of the present invention include a block having a repeating unit selected from any of the structures shown in Tables 1 to 3 below and an optional block selected from the structures shown in Tables 4 and 5 below. And a block copolymer composed of a block having a repeating unit as a repeating unit, but the present invention is not limited to these.

[0077]

[Table 1]

[0078]

[Table 2]

[0079]

[Table 3]

[0080]

[Table 4]

[0081]

[Table 5]

[0082]

[Table 6]

[0083]

[Table 7]

[0084]

[Table 8]

[0085]

[Table 9]

[0086]

[Table 10]

The resistance of the insulating block or insulating phase in the copolymer of the present invention is preferably at least 10 ¹³ Ωcm, particularly preferably at least 10 ¹⁴ Ωcm. When the resistance value of the insulating block becomes lower than the above value, transport charges enter the insulating block, causing troubles such as a decrease in charge transportability, a decrease in photosensitivity, an increase in residual potential, and a decrease in repetition stability. . It is difficult to directly measure the electric resistivity in the copolymer, and the electric resistivity of a polymer having the same structure as the insulating block or the insulating phase can be used instead.

The charge mobility of the charge-transporting block or charge-transporting phase in the copolymer of the present invention is one factor that governs the response speed of the electrophotographic photoreceptor. It is suitably used for the electrophotographic apparatus. In the electrophotographic apparatus of the present invention, the charge mobility of the charge transporting block or the charge transporting phase in the copolymer is at least 10 ⁻⁷ cm ² / Vs, at least in the electric field intensity range used for development.
It is preferable that it is above. This charge mobility is more preferably at least 10 ^-6 cm ² / Vs. It is difficult to directly measure the charge mobility of the charge transport block or the charge transport phase, and the charge mobility of the charge transport polymer having the same structure as the charge transport block or the charge transport phase is difficult. Can be substituted. The mobility can be measured by a Time-of-Flight method, which is a common method in the art, and is represented by a value at an electric field strength of 5 V / μm.

The phase separation structure of the charge transporting phase and the insulating phase of the copolymer of the present invention may be any phase structure such as a sea-island structure, a cylinder-type structure, a lamellar structure, or a modulation structure. The direct observation of the phase separation state in the copolymer includes a method of observing a stained section with a transmission electron microscope. However, as described above, since it is difficult to measure the electric resistance and charge mobility of the phase in the copolymer, it is difficult to determine whether the phase is directly separated into the charge transporting phase and the insulating phase. It is difficult to confirm. However, due to the nature of the polymer, if a phase-separated structure is confirmed in a copolymer of blocks composed of two or more types, each phase can be regarded as composed of the same type of blocks. Therefore, it is a copolymer composed of a charge transport block and an insulating block,
If the phase separation can be confirmed by any method, it can be considered that the phase is separated into a phase composed of the charge transport block and a phase composed of the insulating block. As a matter of course, the phase composed of the charge transporting block is a charge transporting phase, and the phase composed of the insulating block is an insulating phase. As a method for confirming the phase separation, there are, for example, a light scattering method, an X-ray small angle scattering method, and a thermal analysis in addition to the microscopic method.

The conductive particles in the protective layer used in the present invention
As a conductive or semiconductive carbohydrate
Metals, such as zinc, aluminum, copper, iron, stainless steel
Metal, nickel, chromium, titanium, etc.), metal oxidation
Object (TiO_Two, SnO_Two, Sb _TwoO_Three, In_TwoO_Three, Z
nO, MgO, etc.)
Oxides (for example, ZnO-Al_TwoO_Three, SnO_Two-S
b_TwoO_Three, In_TwoO_Three-SnO_Two, ZnO-TiO_Two,
MgO-Al_TwoO_Three, FeO-TiO_Two), Conductive glass
Materials, ceramic materials, and the like. Also,
Carbide the surface of insulating inorganic or organic filler
Metal oxides, metal oxides doped with dopants,
Cover with conductive glass material, ceramic material, etc.
Particles.

As the conductive particles, the surface resistance of the protective layer can be easily controlled, and a transparent film can be easily obtained.
Titanium oxide, tin oxide, and tin oxide doped with antimony are particularly preferred.

The particle diameter of the conductive particles is preferably 0.3 μm or less, more preferably 0.01 μm, from the viewpoint of maintaining the surface smoothness while maintaining an appropriate surface resistance value in the outermost surface layer. ０．３0.3 μm. Here, the particle size of the conductive particles refers to the particle size of the aggregate (secondary particles) when the conductive particles form an aggregate, and the conductive particles form the aggregate. If not, it refers to the particle size of each conductive particle (primary particle).

The content of the conductive particles in the protective layer depends on the conductivity of the particles, the particle size, the shape, and the dispersion state.
80% by weight, preferably in the range of 10 to 70% by weight, and the surface resistance of the protective layer is 10 ⁹ Ωcm or more;
It is preferably at least 10 ¹¹ Ωcm, more preferably 10 ¹² Ωcm.
It is preferable to add so as to be 10 to 10 ¹⁵ Ωcm.

If the resistance is lower than this, the image becomes unclear, and if the resistance is higher than this, the residual potential tends to be too high to obtain a sufficient contrast.

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

A dispersant for dispersing the conductive particles in the resin may be added to the protective layer. The type of the dispersant is selected according to the types of the conductive particles and the resin, and examples thereof include an anionic type, a cationic type, a non-ionic type, and a silane coupling agent.

The dispersion of the conductive particles and the copolymer can be performed using a dyno mill, a sand grind mill, or a ball mill.

Antioxidants, light stabilizers, heat stabilizers, etc. are added to the protective layer for the purpose of preventing the deterioration of the photoreceptor due to ozone or oxidizing gas generated in the electrophotographic apparatus, or light or heat. can do. As the antioxidant, known compounds can be used, and examples thereof include hindered phenol, hindered amine, paraphenylenediamine, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. . As the light stabilizer, known ones can be used, for example, derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine, and electron withdrawing properties that can deactivate the photoexcited state by energy transfer or charge transfer. And a compound or an electron donating compound.

Further, in the electrophotographic photoreceptor of the present invention, various particles other than conductive particles can be dispersed and contained in the protective layer. For example, insulating particles such as a fluororesin, a silicone resin, and an inorganic filler may be dispersed for the purpose of reducing surface wear, improving transferability, improving cleanability, and the like.

As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method can be used.

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

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

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

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

When the photosensitive layer of the electrophotographic photosensitive member of the present invention is of a single-layer type, it can be prepared by applying a binder resin in which a charge generating material is dispersed. Also,
The photosensitive layer may contain a charge transporting low molecular weight compound and / or a charge transporting high molecular weight compound. Furthermore, a material having electron affinity can be included for the purpose of improving photosensitivity, reducing residual potential, and the like. Furthermore, in order to maintain chemical stability, an antioxidant and / or an ultraviolet absorber can be included.

The mixing ratio (weight ratio) of the charge generating material and the binder resin in the photosensitive layer in the single-layer type photosensitive member of the present invention is 1: 1.
The range of 1-1: 100 is preferred. More preferably,
It is set in the range of 1: 3 to 1:50. When the compounding ratio of the charge generation material to the binder resin is larger than the above range, dark decay is increased and mechanical properties are deteriorated. If the amount is less than the above range, problems such as a decrease in photosensitivity and an increase in residual potential occur. In addition, the thickness of the photosensitive layer in the single-layer type is generally
1 to 100 μm is suitable, preferably 5 to 50 μm
Is set in the range. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used.

When the photosensitive layer of the electrophotographic photoreceptor of the present invention is of a laminated type, the charge generation layer is formed by dispersing or dissolving a charge generation material by a vacuum evaporation method or dispersing or dissolving the charge generation material in a binder resin. It can be produced by coating a conductive support or an undercoat layer. Further, the charge generation layer may contain a charge transporting low molecular weight compound and / or a charge transporting high molecular weight compound. Furthermore, the charge generation layer may include an antioxidant and / or an ultraviolet absorber to maintain chemical stability.

The compounding ratio (weight ratio) of the charge generating material and the binder resin in the charge generating layer of the laminated photoreceptor of the present invention is 1
The range of 0: 1 to 1:10 is preferred. More preferably,
It is set in the range of 3: 1 to 1: 1. If the compounding ratio of the charge generating material to the binder resin is larger than the above range, dark decay increases and mechanical properties deteriorate.

If the amount is less than the above range, problems such as a decrease in photosensitivity and an increase in residual potential occur. The thickness of the charge generation layer used in the present invention is generally 0.05 to 5 μm.
m is appropriate, and is preferably set in the range of 0.1 to 2.0 μm. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used.

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

The phthalocyanine-based compound has an oscillation wavelength of 60 nm, which is an emission wavelength of an LED or a laser diode which is currently used as a light source in a digital electrophotographic apparatus.
Since it has excellent photosensitivity in the range of 0 to 850 nm, it is particularly preferable as a charge generation material used in the photosensitive layer of the present invention. The phthalocyanine-based compound is, specifically, a metal-free phthalocyanine and a metal phthalocyanine. As the central metal of the metal phthalocyanine, Cu, Ni, Zn, Co, Fe,
V, Si, Al, Sn, Ge, Ti, In, Ga, M
g, Pb, etc., and oxides of these central metals;
Hydroxides, halides, alkylated compounds, alkoxylated compounds and the like can also be used. Specific examples include metal-free phthalocyanine, titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, vanadyl phthalocyanine, chloroindium phthalocyanine, dichlorotin phthalocyanine, and the like. Further, those having an arbitrary substituent in these phthalocyanine rings can also be used. Further, those in which an arbitrary carbon atom in these phthalocyanine rings is substituted with a nitrogen atom are also effective. As the form of these phthalocyanine compounds, it is possible to use amorphous or all polymorphic forms.

Of these phthalocyanine-based compounds,
Titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, and dichlorotin phthalocyanine have particularly excellent photosensitivity and are particularly preferred as charge generation materials.

Examples of the binder resin used for the single-layer type photosensitive layer and the laminated type charge generation layer in the electrophotographic photoreceptor of the present invention 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, vinyl chloride-vinyl acetate copolymer, silicone resin, phenol resin, poly-N-vinyl carbazole resin, etc., but are not limited thereto. Not something. These binder resins can be block, random or alternating copolymers. These binder resins can be used alone or in combination of two or more.

As the charge transport layer of the laminated type in the electrophotographic photoreceptor of the present invention, a known charge transport layer used as a charge transport layer in a conventional laminated photoreceptor can be used.
For example, benzidine compounds, amine compounds, hydrazone compounds, stilbene compounds, hole transporting low molecular weight compounds such as carbazole compounds or fluorenone compounds, malononitrile compounds, electron transporting low molecular weight compounds such as diphenoquinone compounds. , Alone or 2
A solid solution film in which molecules are dispersed uniformly in an insulating resin such as polycarbonate, polyarylate, polyester, polysulfone, and polymethyl methacrylate, or a polymer compound having its own charge transporting ability. Can be. In addition, selenium,
An inorganic substance having a charge transporting ability, such as amorphous silicon or amorphous silicon carbide, can also be used. Examples of the charge transporting polymer compound include a polymer compound having a charge transporting group such as polyvinylcarbazole in a side chain, and a group having a charge transporting function as disclosed in JP-A-5-232727. And a polysilane having a main chain of Of course, the copolymer used for the protective layer of the electrophotographic photoreceptor of the present invention can be used for the charge transport layer.

The thickness of the charge transport layer used for the laminated photosensitive layer of the electrophotographic photosensitive member of the present invention is set to 1 to 100 μm, preferably 5 to 50 μm. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used. In addition, those capable of vapor phase film formation can be directly formed by a vacuum evaporation method or the like.

In the electrophotographic photoreceptor of the present invention, a charge transporting polymer compound is preferably used as the charge transporting substance used in the charge transporting layer in contact with the protective layer.
The reason is that, in the photoreceptor manufacturing process, when a charge transport layer and a layer containing the copolymer before cross-linking as a main matrix component are laminated and formed, a low molecular weight is added to the charge transport layer in contact with the copolymer before cross-linking. When a charge transporting substance that is a compound is used,
The charge-transporting low-molecular compound is mixed into the layer containing the copolymer before cross-linking as a main matrix component, the insulating property of the insulating phase is reduced, and the mixed molecules become charge traps and increase the residual potential. This is because obstacles such as a decrease in transport ability and a decrease in light sensitivity occur. This problem is particularly noticeable when each layer is formed by a wet coating method. Of course, these problems can be solved by selecting, as the coating solvent for the upper layer, one that does not easily dissolve and swell the lower layer, or by selecting, as the insulating block, one that is incompatible with the charge-transporting low-molecular compound. It is possible to avoid.

It is known, however, that polymers generally undergo phase separation without being compatible with each other, and a charge transporting polymer compound is used as a charge transporting layer in contact with the crosslinked copolymer. In the case where is used, since the phase is separated without being compatible with the insulating block in the crosslinked copolymer, the problem of mixing as described above hardly occurs, and restrictions on selection of materials and manufacturing methods are imposed. It has the advantage of being eliminated.

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. The electrophotographic apparatus includes an electrophotographic photosensitive member and an electrophotographic photosensitive member. A charging unit for charging the body, an exposure unit for exposing the electrophotographic photosensitive member charged by the charging unit, a developing unit for developing a portion exposed by the exposure unit, and a developing unit for developing the electrophotographic photosensitive member by the developing unit. A device having a transfer unit for transferring an image is used. Although any developing means may be used in the electrophotographic apparatus, in the electrophotographic apparatus employing the liquid developing method, the electrophotographic photosensitive member of the present invention which has excellent solvent resistance and has no problem such as cracks is preferably used. it can. Furthermore, as the charging means provided in the electrophotographic apparatus, any type may be used, but a contact-type charging means, in particular,
An electrophotographic apparatus that employs a contact-type charging unit in which an AC voltage is superimposed on a DC voltage can be preferably used because it has excellent wear resistance. Examples of such an electrophotographic apparatus include an analog exposure type electrophotographic copying machine, a laser exposure type digital electrophotographic copying machine, an electrophotographic facsimile, a laser beam printer, an LED printer, a liquid crystal shutter printer, and the like.

A process cartridge may be formed by combining the electrophotographic photosensitive member of the present invention with one or more of a cleaning unit, a charging unit, and a developing unit. Also,
The process cartridge of the present invention is detachable from the main body of the electrophotographic apparatus, and constitutes the electrophotographic apparatus together with the main body of the electrophotographic apparatus.

[0120]

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples, and those skilled in the art can modify the following examples based on known knowledge of electrophotographic technology. Synthesis Example 1 : Reactive polymerization initiator 4,4′-azobis (4
Synthesis of -cyanovaleric chloride) Thionyl chloride (220 ml) was ice-cooled, and 4,4'-azobis (4-cyanovaleric acid) (100 g) was gradually added. This was heated at 30 ° C. for 6 hours, and excess thionyl chloride was distilled off under reduced pressure. The residue was recrystallized from chloroform to give 42
g of 4,4'-azobis (4-cyanovaleric chloride)
Crystals were obtained. Synthesis Example 2 N, N-bis (p, m-dimethylphenyl) -N-
100 g of [(m, m'-bismethoxycarbonylethyl) phenyl] amine, 200 g of ethylene glycol and 5 g of tetrabutoxytitanium were heated and refluxed for 3 hours in a nitrogen stream. N, N'-bis (p, m-dimethylphenyl) -N, N'-bis [p- (2-methoxycarbonylethyl) phenyl]-[1,1'-biphenyl] -4,
After confirming that the 4'-diamine has been consumed, 0.1 g
The pressure was reduced to 5 mmHg, the mixture was heated to 230 ° C. while distilling off ethylene glycol, and the reaction was continued for another 5 hours. Thereafter, the mixture was cooled to room temperature, methylene chloride was added to dissolve the insoluble matter, and the precipitate was reprecipitated from acetone to obtain 90 g of a prepolymer having hydroxy groups at both ends. The weight average molecular weight of the obtained prepolymer was 7.4 × 10 ⁴ .

43 g of the above prepolymer and 0.5 g of triethylamine were dissolved in 120 ml of toluene and cooled to 0 ° C. or lower. A solution of 5.6 g of 4,4′-azobis (4-cyanovaleric chloride) obtained in Synthesis Example 1 suspended in 20 ml of toluene was added dropwise thereto. After reacting at room temperature for 1 hour, the reaction was carried out at 30 ° C. for 6 hours. The solvent was distilled off from this, and it was dissolved by adding tetrahydrofuran, added dropwise to methanol, stirred for 1 hour, and filtered. This reprecipitation operation was repeated twice more. The remaining compound is dried to charge-transport polymer 4 having azo-type polymerization initiation groups at both terminals.
1 g was obtained.

6 g of a charge-transporting polymer having an azo-type polymerization initiating group at both terminals, 6 g of tert-butyl methacrylate, and 2 g of 3-trimethoxysilylpropyl methacrylate were dissolved in 120 ml of tetrahydrofuran. Heated for hours. This solution was added dropwise to methanol, stirred for 1 hour, and filtered off. The obtained solid is sufficiently washed with cyclohexane, and a block comprising a charge transporting block having a triarylamine structure and an insulating block having an alkoxysilyl group as a crosslinkable functional group represented by the following structural formula (7). A copolymer was synthesized.

[0123]

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Wherein Y ¹ and Z ¹ are each tert-C
₄ H ₉ or C ₃ H ₇ Si (OCH ₃ ) ₃ , where o, p and q represent positive integers. The weight average molecular weight of the charge transporting polymer is 3.1 × 10
^4. The weight average molecular weight of the finally obtained block copolymer is 5.5 × 10 ⁴ , and the peak corresponding to protons specific to both blocks in the ¹ H-NMR spectrum of the obtained block copolymer is obtained. From the integral ratio, the weight composition ratio of the charge transporting block and the insulating block is calculated to be about 2: 3. Further, the weight composition ratio of the crosslinked portion and the non-crosslinked portion in the insulating block is calculated to be about 2: 8. Synthesis Example 3 N, N-bis (p, m-dimethylphenyl) -N-
[(M, m'-bismethoxycarbonylethyl) phenyl] amine is converted to N, N'-bis (p, m-dimethylphenyl) -N, N'-bis [p- (2-methoxycarbonylethyl) phenyl]- [3,3′-dimethyl-1,
1′-biphenyl] -4,4′-diamine was obtained in the same manner as in Synthesis Example 2 except that a charge transporting polymer having an azo type polymerization initiating group at both terminals was obtained.

6 g of the charge transporting polymer having a polymerization initiator at the terminal, 6 g of tert-butyl methacrylate,
-2 g of hydroxy methacrylate in 120 ml of toluene
And then heated at 65 ° C. for 95 hours after purging with nitrogen. This solution was added dropwise to methanol, stirred for 1 hour, and filtered off. The obtained solid is sufficiently washed with cyclohexane, and a block including a charge transporting block having a triarylamine structure and an insulating block having a hydroxy group as a crosslinkable functional group represented by the following structural formula (8) is used. 9 g of a polymer was obtained.

[0126]

Embedded image

(Where Y ² and Z ² are each tert-C
₄ H ₉ or C ₂ H ₅ OH, and o, p, and q represent positive integers.) The weight average molecular weight of the obtained copolymer is 12 × 10 ⁴ , and that of the obtained block copolymer is ^From the integration ratio of the peaks corresponding to the protons specific to both blocks in the ¹ H-NMR spectrum, the weight composition ratio of the charge transporting block and the insulating block is calculated to be about 3: 2. Similarly, the weight composition ratio of the crosslinked portion and the non-crosslinked portion in the insulating block is calculated to be about 2: 8. Synthesis Example 4 In the same manner as in Synthesis Example 3, a charge transporting polymer having an azo-type polymerization initiation group at a terminal was obtained.

70 g of the obtained charge-transporting polymer having an azo-type polymerization initiating group at the end was dissolved in 1300 ml of toluene, 240 g of styrene and 20 g of methacrylic acid were added, and the mixture was purged with nitrogen and heated at 65 ° C. for 70 hours. This was dropped into methanol, and the precipitated solid was separated by filtration. When the filtrate was analyzed, styrene, methacrylic acid, and a styrene-methacrylic acid copolymer were detected. Next, 80 g of the filtered solid was finely pulverized, placed in 720 ml of xylene, stirred for 24 hours, and then mixed with 350 ml of cyclohexane.
Was added, and the mixture was separated into insoluble matter and soluble matter. As a result of ¹ H-NMR spectrum and GPC analysis, the soluble component was an unreacted charge-transporting polymer and a block copolymer rich in charge-transporting block, and the insoluble component was represented by the following structural formula (9). It was the block copolymer shown.

[0129]

Embedded image

(Wherein Y ³ and Z ³ each represent COOCH ₃
Or C ₆ H ₅ , and o, p, and q represent positive integers) From the analysis of the ¹ H-NMR spectrum, the weight composition of the charge-transporting block and the charge-transporting inactive block of the target block copolymer is obtained. The ratio was approximately 32:68. Also,
The weight ratio of styrene units to methacrylic acid units in the charge transport inert block was approximately 80:20. (Example 1) Polycarbonate Z resin (Iupilon Z-
To a solution of 8 parts by weight of 400, manufactured by Mitsubishi Gas Chemical Co., Ltd. in 89 parts by weight of toluene was added 3 parts by weight of dichlorotin phthalocyanine, and the mixture was dispersed by a sand mill for 24 hours to prepare a coating liquid. The obtained coating solution was applied by dip coating on an aluminum plate and an aluminum drum,
The resultant was dried by heating at 0 ° C. for 1 hour to form a photosensitive layer having a thickness of 15 μm. Next, 8 parts by weight of the block copolymer of Synthesis Example 2 was dissolved in 92 parts by weight of toluene, and 10 parts by weight of antimony-doped tin oxide fine powder (S-1, manufactured by Mitsubishi Materials Corporation, primary particle size: 0.01 μm) Parts, and mixed and dispersed by a ball mill, and then a coating solution containing 0.5 parts by weight of acetic acid is spray-coated on the photosensitive layer, and is heated and cured at 150 ° C. for 30 minutes to form a surface protective layer having a thickness of 3 μm. And a copolymer containing a charge transporting block and an insulating block whose molecular structure is three-dimensionally formed by crosslinking in a protective layer, and an electrophotographic photoreceptor containing conductive particles having the structure shown in FIG. Formed.

When this protective layer was observed with a transmission electron microscope using a ruthenic acid staining method, a phase-separated structure was observed. Also, the scale of the phase separation structure is about 0.03μ.
m.

The electrophotographic photoreceptor thus obtained was subjected to an electrostatic copying paper tester (Electrostatic Analyzer EPA-8100, manufactured by Kawaguchi Electric Works).
Was used to evaluate the electrophotographic characteristics in an environment of normal temperature and normal humidity (25 ° C., relative humidity of 50% RH). After adjusting the corona discharge voltage and charging the surface of the photoreceptor to -750 V, the halogen lamp light monochromatized to 750 nm through an interference filter was adjusted to have a light intensity of ² mW / m2 on the surface of the photoreceptor. For 7 seconds, and the half-life exposure amount E _50% was determined from the photoinduced potential decay curve. The potential 7 seconds after the start of exposure was defined as the residual potential. E _50% was 6.5 mJ / m ² , and the residual potential was −90 V.

Further, this photoreceptor was mounted on a laser exposure type printer (“Laser Press 4161II” manufactured by Fuji Xerox Co., Ltd.) to evaluate image blur under high temperature and high humidity (28 ° C./85% relative humidity), and An actual machine running test of 30,000 sheets was performed under humidity (25 ° C./relative humidity 50%). Image blur was evaluated by visual recognition. The drum rotation speed of this laser exposure type printer is 58 rpm.
m, the light source for forming a latent image is a laser diode having an oscillation wavelength of 780 nm, the charger is a contact-type roller charger in which an AC voltage is superimposed on a DC voltage, and the time between exposure and charging is 0.9.
7 seconds, exposure-development time 0.18 seconds. FIG. 5 shows a schematic diagram of the present apparatus. 5, reference numeral 11 denotes a photosensitive drum, 13 denotes a charging roll, 14 denotes an exposure laser optical system, 14a denotes a laser beam, 15 denotes a developing device, 16 denotes a transfer roll, 17 denotes a cleaning blade, and 18 denotes a sheet. Is shown. The difference between the thickness of the photosensitive layer after the 10,000-sheet running test on the actual machine and the thickness before running on the actual machine was taken as the abrasion loss.

There was no image blur, and the abrasion amount was 0.3 μm.

(Comparative Example 1) A photosensitive layer was formed on an aluminum plate and an aluminum drum in the same manner as in Example 1. Next, 8 parts by weight of the block copolymer of Synthesis Example 2 was dissolved in 92 parts by weight of toluene, and a coating solution containing 0.5 part by weight of acetic acid was spray-coated on the photosensitive layer.
Heat-cured at 50 ° C. for 30 minutes to form a surface protective layer having a thickness of 3 μm, and the protective layer contains no conductive particles;
An electrophotographic photoreceptor containing a copolymer containing a charge transport block and an insulating block whose molecular structure was made three-dimensional by crosslinking was formed.

As a result of evaluation in the same manner as in Example 1, E
_50% was 7 mJ / m ² , and the residual potential was -100 V.
Further, an actual machine test was performed in the same manner as in Example 1. There was no image blur, and the abrasion amount was 1.3 μm.

(Example 2) 20 parts by weight of a zirconium alkoxide compound (trade name: ORGATICS ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.) and γ were placed on an aluminum plate and a honed aluminum drum.
-Aminopropyltriethoxysilane (trade name: A11
00, manufactured by Nippon Unicar Co., Ltd.) and 2 parts by weight of polyvinyl butyral resin (Eslec BM-S, manufactured by Sekisui Chemical Co., Ltd.)
A solution consisting of 1.5 parts by weight and 70 parts by weight of n-butanol was applied by a dip coating method.
After heating and drying for a minute, an undercoat layer having a thickness of 1.0 μm was formed. Next, 4 parts by weight of chlorogallium phthalocyanine microcrystals were mixed with a vinyl chloride-vinyl acetate copolymer (trade name: UCA).
R solution vinyl resin VMCH, manufactured by Union Carbide Co.) 2 parts by weight, xylene 67 parts by weight, and butyl acetate 33 parts by weight, and treated with a 1 mmφ glass bead for 2 hours by a sand grinder and dispersed.
The obtained coating solution was applied on the undercoat layer by a dip coating method, and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm. Next, 20 parts by weight of a compound composed of a repeating unit represented by the following structural formula (10) having a molecular weight of 80,000, which is a polymer charge transporting material, is dissolved in 80 parts by weight of monochlorobenzene, and immersion coating is performed on the charge generation layer. And dried by heating at 135 ° C. for 1 hour to form a charge transport layer having a thickness of 20 μm.

[0138]

Embedded image

Next, 10 parts by weight of the block copolymer obtained in Synthesis Example 3 and 2 parts by weight of a trivalent isocyanate compound represented by the following structural formula (11) as a crosslinking agent were dissolved in 90 parts by weight of cyclohexanone. In the solution, tin oxide fine powder (S-1, manufactured by Mitsubishi Materials Corporation, primary particle size 0.01 μm)
m) 10 parts by weight were added, mixed and dispersed by a ball mill, and applied on the charge transport layer by dip coating.
Heat-curing at 50 ° C. for 60 minutes to form a surface protective layer having a thickness of 5 μm, and the charge transport block and the insulating block of the structure shown in FIG. And an electrophotographic photosensitive member containing conductive particles.

[0140]

Embedded image

When this protective layer was observed with a transmission electron microscope using a ruthenic acid staining method, a phase-separated structure was observed. The scale of the phase separation structure is about 0.06μ.
m.

The thus obtained electrophotographic photosensitive member was evaluated in the same manner as in Example 1. As a result, E _50% was 4.5 mJ.
/ M ² , and the residual potential was −40 V. Example 1
When an actual machine test was performed in the same manner as in the above, there was no image blur, and the abrasion amount was 0.5 μm.

Comparative Example 2 An undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on aluminum and a honed aluminum drum in the same manner as in Example 2.

Next, 10 parts by weight of the block copolymer obtained in Synthesis Example 3 and 1.5 parts by weight of the trivalent isocyanate compound represented by the above structural formula (11) as a crosslinking agent were dissolved in 90 parts by weight of cyclohexanone. After applying the solution to the charge transport layer by dip coating,
And heat-curing for 60 minutes to form a surface protective layer having a thickness of 5 μm. The protective layer does not contain conductive particles, and includes a charge transporting block and an insulating block whose molecular structure is made three-dimensional by crosslinking. An electrophotographic photoreceptor containing the copolymer was formed.

As a result of evaluation in the same manner as in Example 1, E
_50% was 3.9 mJ / m ² , and the residual potential was −60V. Further, an actual machine test was performed in the same manner as in Example 1. There was no image blur, and the abrasion amount was 1.6 μm.

Example 3 An undercoat layer, a charge generation layer and a charge transport layer were sequentially formed on aluminum and a honed aluminum drum in the same manner as in Example 2.

Next, a solution of 10 parts by weight of the block copolymer obtained in Synthesis Example 4 in 80 parts by weight of toluene and 10 parts by weight of isopropanol was added to a fine powder of tin oxide (S-
1. Mitsubishi Materials Corporation, primary particle size 0.01μm) 15
After adding a liquid by mixing and dispersing with a ball mill on the charge transport layer by a dip coating method, 13 parts by weight were added.
Heat drying at 5 ° C. for 60 minutes to form a surface protective layer having a thickness of 5 μm. The protective layer contains conductive particles, and the charge transporting block and the insulating block have a three-dimensional molecular structure due to crosslinking. An electrophotographic photoreceptor containing a copolymer containing was formed.

As a result of evaluation in the same manner as in Example 1, E
_50% was 3.6 mJ / m ² , and the residual potential was −20 V. Further, an actual machine test was performed in the same manner as in Example 1. There was no image blur, and the abrasion amount was 0.8 μm.

Example 1 and Comparative Example 1, Example 2 and Comparative Example 2
By comparing the above, it is possible to include the conductive particles in the protective layer including the copolymer including the charge transport block and the insulating block whose molecular structure has been three-dimensionally formed by crosslinking, without deteriorating the electrical characteristics. It can be seen that the abrasion resistance is improved. Also, by comparing Example 2 and Example 3, it is found that the abrasion resistance is improved by making the molecular structure three-dimensional by crosslinking the copolymer containing the charge transporting block and the insulating block. I understand.

[0150]

The electrophotographic photoreceptor of the present invention comprises an electrophotographic photoreceptor having at least a photosensitive layer and a protective layer provided on a conductive substrate, wherein the protective layer comprises at least conductive particles and a charge transporting material. Since it contains a copolymer containing a block and an insulating block, it is possible to provide an electrophotographic photoreceptor having excellent abrasion resistance when used repeatedly and having a low residual potential.

By including these electrophotographic photosensitive members having excellent charge transporting ability and excellent mechanical properties in an electrophotographic apparatus and a process cartridge, an electrophotographic apparatus and a process cartridge having excellent repetition stability and reliability can be obtained. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a first embodiment of an electrophotographic photoconductor of the present invention.

FIG. 2 is a cross-sectional view schematically showing a second embodiment of the electrophotographic photosensitive member of the present invention.

FIG. 3 is a cross-sectional view schematically showing a third embodiment of the electrophotographic photosensitive member of the present invention.

FIG. 4 is a cross-sectional view schematically showing a fourth embodiment of the electrophotographic photoconductor of the present invention.

FIG. 5 is a sectional view schematically showing a part of the electrophotographic apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Conductive support, 2 ... Photosensitive layer, 3 ... Undercoat layer, 4 ... Charge generation layer, 5 ... Charge transport layer, 6 ... Surface protective layer, 11 ... Photoconductor drum, 13 ... Charging roll, 14 ... Exposure laser optical system, 15: developing device, 16: transfer roll, 17 ...
Cleaning blade, 18 ... paper.

Claims (7)

[Claims] 1. An electrophotographic photosensitive member having at least a photosensitive layer and a protective layer provided on a conductive substrate, wherein the protective layer comprises at least conductive particles, and a charge transport block and an insulating block. An electrophotographic photoreceptor comprising a coalescence. 2. The electrophotographic photoreceptor according to claim 1, wherein the copolymer containing the charge transport block and the insulating block has a three-dimensional molecular structure by crosslinking. 3. The electrophotographic photoreceptor according to claim 1, wherein a cross-linking site in the copolymer containing the charge transport block and the insulating block exists in the insulating block. 4. The method according to claim 1, wherein the copolymer containing the charge transport block and the insulating block is phase-separated into a phase composed of the charge transport block and a phase composed of the insulating block. The electrophotographic photoreceptor according to any one of claims 1 to 3. 5. The repeating unit of a charge transporting block in a copolymer containing a charge transporting block and an insulating block contains at least a repeating unit having a triarylamine structure. The electrophotographic photosensitive member according to claim 1. 6. The electrophotographic photoreceptor according to claim 1, and at least one unit selected from the group consisting of a charging unit, a developing unit, a cleaning unit, and a discharging unit. A process cartridge comprising: an electrophotographic apparatus; 7. The electrophotographic photosensitive member according to claim 1, a charging unit for charging the electrophotographic photosensitive member, and exposing the electrophotographic photosensitive member charged by the charging unit. An electrophotographic apparatus, comprising: an exposure unit that develops a portion exposed by the exposure unit; and a transfer unit that transfers an image developed on the electrophotographic photosensitive member by the development unit. apparatus.