JP2013097270A - Electrophotographic photoreceptor, electrophotographic photoreceptor cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that prevents the occurrence of filming, poor cleaning, or abnormal noise and has excellent wear resistance on a mechanical physicality, exhibits high-speed response and a sufficiently low exposure unit potential on an electrical property, and has excellent gas resistance and image memory characteristics; an electrophotographic photoreceptor cartridge; and an image forming apparatus.SOLUTION: Provided is an electrophotographic photoreceptor that uses a charge transport material having a specific structure and a specific polyester resin in combination as a binder resin to express excellent performance on a mechanical property, and exhibits high mobility and a sufficient residual potential during exposure to realize excellent image quality property. Also provided are an electrophotographic photoreceptor cartridge, and an image forming apparatus.

Description

  The present invention relates to an electrophotographic photosensitive member having excellent electrical characteristics and mechanical characteristics, an electrophotographic photosensitive member cartridge manufactured using the electrophotographic photosensitive member, and an image forming apparatus.

  The electrophotographic technology is widely used as a copying machine, a printer, and a printing machine because a high-quality image can be obtained immediately. The electrophotographic photosensitive member (hereinafter referred to as “photoreceptor” as appropriate), which is the core of electrophotographic technology, is easy to form with no pollution, and can meet a wide range of electrophotographic process requirements in terms of performance. Photoconductors using organic photoconductive materials are widely used.

  In recent years, due to the demand for higher image quality, the diameter of toner has been reduced. In particular, chemical toners often have a shape close to a sphere. This is likely to occur, and as a result, there is a high possibility of image defects such as dirt. For this reason, measures are often taken to prevent the toner from slipping through contact of the cleaning blade with the photosensitive member with a strong pressure.

  When the contact pressure of the cleaning blade to the photosensitive member increases, chattering due to the so-called stick-slip phenomenon in which the blade repeatedly sticks / slides with the outermost surface of the photosensitive member is generated, and as a result, the risk of generating abnormal noise increases. In addition, the external component, toner carrier, paper powder, and the like, which are toner components, rotate while being pressed against the photoconductor through the nip through the cleaning blade, thereby reducing the life due to increased wear of the photosensitive layer. And image defects due to the occurrence of scratches in the circumferential direction are also likely to occur. In addition, if fine scratches are generated on the surface of the photosensitive member, the toner component is fixed as a result, which makes it difficult to remove with a cleaning blade, so that a so-called filming phenomenon is likely to occur, resulting in a persistent image defect. Risk is also getting higher.

  Even under such severe use conditions, the photoreceptor is required to have surface mechanical properties that minimize image defects, abnormal noise, and lifetime reduction. As a means of improving the surface mechanical properties, the use of a polyester resin, especially a polyarylate resin (totally aromatic polyester resin) having a high elastic deformation rate as the outermost layer of the photoreceptor, It has been put to practical use as a means to meet the demand for improvement.

  On the other hand, as the electrophotographic apparatus is reduced in size and speeded up, the diameter of the photoconductor is reduced, and further improvement in electrical response (fast decay of the surface potential of the photoconductor after exposure) is required. In order to provide an electrophotographic photoreceptor satisfying these characteristics, it is necessary to develop a highly functional charge transport material that exhibits high mobility and a sufficiently low residual potential upon exposure. In order to solve these problems, a search for a charge transport material having a triarylamine analog as a basic skeleton and further expanding the π-electron system with a styryl group or the like has been actively conducted, and many reports have been made. Yes. (Patent Documents 1 to 10).

JP-A-7-36203 JP 2002-80432 A JP 2006-8670 A JP 2008-83105 A Japanese Patent No. 4407537 JP-A-6-27702 JP 2003-131409 A JP 2005-289877 A JP 2008-74714 A JP 2007-122036 A

  As described above, a conventional polycarbonate-based binder resin is not sufficient to be suitably used for a chemical toner, and a polyester-based resin has been studied as a candidate material instead. Compared with polycarbonate resin, the polarity of the molecule is larger and the charge transporting ability of the charge transporting material is reduced. Therefore, when using conventional charge transporting materials, the response, residual potential, etc. are insufficient and practical. Increasing number of cases cannot withstand. In particular, even when a known charge transport material having a high charge mobility is used, the response is excellent, but the residual potential is often insufficiently lowered. On the other hand, even if the charge transporting material has a sufficiently low residual potential, many of the materials have low responsiveness and cannot withstand use in high-speed processes. Furthermore, even if the residual potential and responsiveness are good, gas resistance such as ozone and NOx, image memory property, and compatibility with the polyester resin are inferior, and there are many cases that cannot be used.

  The present invention has been made in view of the above-described background art, and its problems are mechanical properties, hardly cause filming, poor cleaning, abnormal noise generation, etc., excellent wear resistance, and high electrical characteristics. An object of the present invention is to provide an electrophotographic photosensitive member, an electrophotographic cartridge, and an image forming apparatus that exhibit responsiveness, sufficiently low exposure portion potential, and are excellent in gas resistance and image memory properties.

As a result of intensive studies, the present inventors have exhibited good performance in terms of mechanical properties by including a charge transport material having a specific structure in a photosensitive layer using a specific polyester resin as a binder resin. In addition, the inventors have found that it is possible to provide an electrophotographic photosensitive member that exhibits high mobility and a sufficient residual potential at the time of exposure, and completed the present invention described below.
The gist of the present invention resides in the following <1> to <5>.
<1> In an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, a charge transport material represented by the following formula (1) and a structural unit represented by the following formula (2) in the photosensitive layer An electrophotographic photosensitive member, comprising a polyester resin having:

(In the formula (1), Ar ¹ is an aryl group having at least an alkoxy group as a substituent, Ar ² and Ar ³ are each independently an arylene group optionally having an alkyl group, and Ar ^{4 to} Ar ⁷ are Each independently represents an aryl group optionally having an alkyl group or an alkoxy group, Ar ⁴ and Ar ⁵ , Ar ⁶ and Ar ⁷ may be bonded to each other, provided that the substituents are bonded to each other; And may form a ring.)

(In formula (2), Ar ^{8 to} Ar ¹¹ each independently represents an arylene group which may have a substituent, X represents a single bond, an oxygen atom, a sulfur atom, or an alkylene group. M represents 0. And represents an integer of 2 or less, and Y represents a single bond, an oxygen atom, a sulfur atom, or an alkylene group.
<2> The electrophotographic photosensitive member according to <1>, wherein Ar ^{4 to} Ar ⁷ are each independently an aryl group having an alkyl group having 10 or less carbon atoms.
<3> The universal hardness of the layer containing the charge transport material represented by the formula (1) and the polyester resin having the structural unit represented by the formula (2) is 170 N / mm ² or more and 220 N / mm ^2. The electrophotographic photosensitive member according to <1> or <2>, wherein the elastic deformation rate is 43% or more.
<4> The electrophotographic photosensitive member according to any one of <1> to <3>, a charging device for charging the electrophotographic photosensitive member, and exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. An electrophotographic photosensitive member cartridge comprising: an exposure device to be formed; and at least one selected from the group consisting of a developing device for developing an electrostatic latent image formed on the electrophotographic photosensitive member.
<5> The electrophotographic photosensitive member according to any one of <1> to <3>, a charging device that charges the electrophotographic photosensitive member, and an electrostatic latent image formed by exposing the charged electrophotographic photosensitive member An image forming apparatus comprising: an exposure device for developing the image; and a developing device for developing the electrostatic latent image formed on the electrophotographic photosensitive member.

  In the present invention, a charge transport material having a specific structure and a polyester resin are contained in a photosensitive layer, thereby being excellent in high-speed response, exhibiting a sufficiently low residual potential, and having high resistance to stress in an electrophotographic process. It is possible to provide an electrophotographic photosensitive member, an electrophotographic photosensitive member cartridge, and an image forming apparatus that enable high-quality image formation.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. 1 is an X-ray diffraction pattern of oxytitanium phthalocyanine used in Examples. It is the graph which showed the load curve with respect to the indentation depth of a photoconductor.

Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and is appropriately modified and implemented without departing from the spirit of the present invention. can do.
<< Charge transport material of the present invention >>
<Structure of the charge transport material of the present invention>
The charge transport material of the present invention is represented by the following formula (1).

(In the formula (1), Ar ¹ is an aryl group having at least an alkoxy group as a substituent, Ar ² and Ar ³ are each independently an arylene group optionally having an alkyl group, and Ar ^{4 to} Ar ⁷ are Each independently represents an aryl group optionally having an alkyl group or an alkoxy group, Ar ⁴ and Ar ⁵ , Ar ⁶ and Ar ⁷ may be bonded to each other, provided that the substituents are bonded to each other; And may form a ring.)

In the above formula (1), Ar ¹ represents an aryl group having at least an alkoxy group. The substituents may be bonded to each other to form a ring. The aryl group usually has 30 or less carbon atoms, preferably 20 or less carbon atoms, more preferably 10 or less carbon atoms, and specific examples thereof include a phenyl group, a naphthyl group, an anthranyl group, and a pyrenyl group. From the viewpoint of electrical characteristics and ease of production, a naphthyl group or a phenyl group is preferable, and a phenyl group is most preferable. The alkoxy group is usually 8 or less carbon atoms, preferably 6 or less carbon atoms, more preferably 4 or less carbon atoms in production, and specifically includes a methoxy group, an ethoxy group, a butoxy group, a tert-butoxy group, and the like. And a methoxy group or an ethoxy group is most preferable. As for the position of the substituent, for example, when Ar ¹ is a phenyl group, the substitution position of the alkoxy group is preferably a para-position or an ortho-position based on the nitrogen atom substitution position, and the para-position is most preferred from the viewpoint of electrical properties. If the number of alkoxy group substitutions in Ar ¹ is too large, the chargeability of the photoreceptor may be lowered. Therefore, it is usually 3 or less, more preferably 2 or less, and most preferably 1. The substituent other than the alkoxy group is not particularly limited, but is usually 30 or less carbon atoms, preferably 20 or less carbon atoms, more preferably 10 or less carbon atoms, specifically a methyl group. Linear alkyl groups such as ethyl group and propyl group, branched alkyl groups such as isopropyl group, tertbutyl group and isobutyl group, cyclic alkyl groups such as cyclohexyl group and cyclopentyl group, phenyl group, naphthyl group and anthranyl group, Examples thereof include aryl groups such as pyrenyl group, halogen atoms such as fluorine atom, chlorine atom and bromine atom, amino groups such as dimethylamino group, diethylamino group and diisopropylamino group, and benzyl group. Among them, an alkyl group having 10 or less carbon atoms is preferable, a linear alkyl group having 4 or less carbon atoms is preferable from the viewpoint of production, and a branched alkyl group having 4 or less carbon atoms is preferable from the viewpoint of compatibility. The substitution position of the alkyl group is not particularly limited. For example, when Ar ¹ is a phenyl group, when the alkoxy group is present at the meta position or the ortho position with a substitution number of 1, with respect to the nitrogen atom substitution position, photosensitivity is obtained. From the viewpoint of the photofatigue property of the body, it is preferable to substitute at the ortho position in order to suppress the ring-closing reaction due to the photochemical reaction, and from the viewpoint of electrical characteristics, it is substituted at the para or ortho position where the electron donating effect is likely to occur. It is preferable. When the alkoxy group is present at the para position with the number of substitutions 1 on the basis of the nitrogen atom substitution position, the ortho position is preferred from the viewpoint of the light fatigue characteristics and electrical characteristics of the photoreceptor.

In the above formula (1), Ar ² and Ar ³ each independently represent an arylene group which may have an alkyl group. The substituents may be bonded to each other to form a ring. Examples of the arylene group include a phenylene group, a naphthylene group, and an anthranylene group. A phenylene group or a naphthylene group is preferable, and a phenylene group is most preferable. Examples of the alkyl group that Ar ² and Ar ³ may have include a linear alkyl group such as a methyl group, an ethyl group, and a propyl group, a branched alkyl group such as an isopropyl group, a tet butyl group, and an isobutyl group, and a cyclohexyl group. And a cyclic alkane such as a cyclopentyl group, a linear alkyl group having 4 or less carbon atoms is preferable from the viewpoint of production, and a branched alkyl group having 4 or less carbon atoms is preferable from the viewpoint of compatibility.

In the above formula (1), Ar ^{4 to} Ar ⁷ each independently represents an aryl group which may have an alkyl group or an alkoxy group. The substituents may be bonded to each other to form a ring, and Ar ⁴ and Ar ⁵ , and Ar ⁶ and Ar ⁷ may be bonded to each other. Usually, it has 30 or less carbon atoms, preferably 20 or less carbon atoms, more preferably 10 or less carbon atoms. Specific examples include phenyl group, naphthyl group, anthranyl group, pyrenyl group, etc. From the viewpoint of easiness, a naphthyl group or a phenyl group is preferable, and a phenyl group is most preferable. The alkyl group that Ar ^{4 to} Ar ⁷ may have is usually 20 or less carbon atoms, preferably 10 or less carbon atoms, more preferably 5 or less carbon atoms, specifically a methyl group or an ethyl group. And linear alkyl groups such as propyl group, branched alkyl groups such as isopropyl group, tertbutyl group and isobutyl group, and cyclic alkyl groups such as cyclohexyl group and cyclopentyl group. Among them, a linear alkyl group having 4 or less carbon atoms is preferable from the viewpoint of production, and a branched alkyl group having 4 or less carbon atoms is preferable from the viewpoint of compatibility. The alkoxy group is usually 8 or less carbon atoms, preferably 6 or less carbon atoms, more preferably 4 or less carbon atoms in production, and specifically includes a methoxy group, an ethoxy group, a butoxy group, a tert-butoxy group, and the like. And a methoxy group or an ethoxy group is most preferable. Among these, an alkyl group is the most preferable. The substitution number of the alkyl group is preferably 1 or 2 for each aryl group. When the substitution number is 1, the substitution position is preferably the para position. When the substitution number is 2, the meta, para position, or ortho, para position is preferable.

In the above (1), from the viewpoint of charge transport efficiency and charge transfer, it is preferable that the π electron cloud spreads as uniformly as possible over the entire molecule and that the symmetry of the molecule is as high as possible. Specifically, Ar ¹ is a phenyl group having an alkoxy group at the para position, Ar ² and Ar ³ are unsubstituted phenylene groups, and Ar ^{4 to} Ar ⁷ have as many identical substituents as possible at the same substitution positions. Or an unsubstituted phenyl group. Further, from the viewpoint of reducing the residual potential, an electron donating group having a substituent constant σp of 0.20 or less is reduced to Ar ¹ to Ar to such an extent that the chargeability is not deteriorated. ⁷ and the electron donating group in that case is preferably an alkyl group. Specifically, Ar ¹ is a phenyl group having an alkoxy group at the para position, Ar ² and Ar ³ are unsubstituted phenylene groups, and all of the para positions of Ar ^{4 to} Ar ⁷ are substituted with alkyl groups. Most preferably.

  In the above (1), among the two double bonds of the butadienyl group, regarding the geometric isomerism of the double bond directly connected to the triarylamine, the trans isomer is preferable from the viewpoint of the spread of the π electron cloud. However, when all are in the trans form, depending on the substituent, the stacking of the molecule is improved, the intermolecular force is increased, and the solubility of the crystal may be lowered. Good. In that case, of the double bond directly bonded to the triarylamine, the proportion that may contain a cis isomer is preferably 15% or less, more preferably 10% or less.

  The structure of the charge transport material suitable for the present invention is exemplified below. The following structures are illustrated to make the present invention more concrete, and are not limited to the following structures unless departing from the concept of the present invention.

≪Polyester resin of the present invention≫
<Structure of the polyester resin of the present invention>
The polyester resin of the present invention has a structural unit represented by the following formula (2).

In formula (2), Ar ^{8 to} Ar ¹¹ each independently represent an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom or an alkylene group. m represents an integer of 0 or more and 2 or less. Y represents a single bond, an oxygen atom, a sulfur atom, or an alkylene group.
In said formula (2), Ar < ⁸ > -Ar < ¹¹ > represents the arylene group which may have a substituent each independently. As carbon number which an arylene group has, it is 6 or more normally, Preferably it is 7 or more, and the upper limit is 20 or less normally, Preferably it is 10 or less, More preferably, it is 8 or less. If the number of carbon atoms is too large, the production cost increases and the electrical characteristics may deteriorate.

Specific examples of Ar ^{8 to} Ar ¹¹ include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, naphthylene group, anthrylene group, phenanthrylene group and the like. Among these, the arylene group is preferably a 1,4-phenylene group from the viewpoint of electrical characteristics. An arylene group may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

Specific examples of the substituents for Ar ^{8 to} Ar ¹¹ include an alkyl group, an aryl group, a halogen group, and an alkoxy group. Among them, considering the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the alkyl group is preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, and is preferably an aryl group. Is preferably a phenyl group or a naphthyl group, a halogen group is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and an alkoxy group is preferably a methoxy group, an ethoxy group, a propoxy group or a butoxy group. In addition, when a substituent is an alkyl group, carbon number of the alkyl group is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 2 or less.

More specifically, Ar ⁸ and Ar ¹¹ each independently preferably have a substituent number of 0 or more and 2 or less, more preferably have a substituent from the viewpoint of adhesion, and in particular, substitution from the viewpoint of wear resistance. It is particularly preferable that the number of groups is one. Moreover, as a substituent, an alkyl group is preferable and a methyl group is particularly preferable.
On the other hand, Ar ⁸ and Ar ¹¹ each independently preferably have 0 or more and 2 or less substituents, and more preferably have no substituents from the viewpoint of wear resistance.

In the above formula (2), Y is a single bond, an oxygen atom, a sulfur atom, or an alkylene group. As the alkylene group, —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and cyclohexylene are preferable, and —CH ₂ —, —CH (CH ₃ ) —, — are more preferable. C (CH ₃ ) ₂ — and cyclohexylene are preferable, and —CH ₂ — and —CH (CH ₃ ) — are particularly preferable.

In the above formula (2), X is a single bond, an oxygen atom, a sulfur atom, or an alkylene group, and among them, X is preferably an oxygen atom. In that case, m is preferably 0 or 1, and most preferably 1.
Specific examples of preferred dicarboxylic acid residues when m is 1 include diphenyl ether-2,2′-dicarboxylic acid residues, diphenyl ether-2,3′-dicarboxylic acid residues, and diphenyl ether-2,4′-dicarboxylic acid. Residue, diphenyl ether-3,3′-dicarboxylic acid residue, diphenyl ether-3,4′-dicarboxylic acid residue, diphenyl ether-4,4′-dicarboxylic acid residue and the like. Among these, considering the simplicity of production of the dicarboxylic acid component, diphenyl ether-2,2′-dicarboxylic acid residue, diphenyl ether-2,4′-dicarboxylic acid residue, diphenyl ether-4,4′-dicarboxylic acid Residues are more preferred, and diphenyl ether-4,4′-dicarboxylic acid residues are particularly preferred.

Specific examples of dicarboxylic acid residues when m is 0 include phthalic acid residues, isophthalic acid residues, terephthalic acid residues, toluene-2,5-dicarboxylic acid residues, p-xylene-2,5- Dicarboxylic acid residue, naphthalene-1,4-dicarboxylic acid residue, naphthalene-2,3-dicarboxylic acid residue, naphthalene-2,6-dicarboxylic acid residue, biphenyl-2,2′-dicarboxylic acid residue, Biphenyl-4,4′-dicarboxylic acid residue may be mentioned, preferably phthalic acid residue, isophthalic acid residue, terephthalic acid residue, naphthalene-1,4-dicarboxylic acid residue, naphthalene-2,6- Dicarboxylic acid residues, biphenyl-2,2′-dicarboxylic acid residues, biphenyl-4,4′-dicarboxylic acid residues, particularly preferably isophthalic acid residues and terephthalic acid residues. It is also possible to use a combination of a plurality of rubonic acid residues. Preferable specific examples include polyarylate resins having structural units represented by the following formulas (3) and (4). In the formulas (3) and (4), the ratio of the isophthalic acid residue to the terephthalic acid residue is usually 50:50, but can be arbitrarily changed. In that case, the higher the ratio of terephthalic acid residues, the better from the viewpoint of electrical characteristics.

  The viscosity average molecular weight of the polyester resin used in the present invention is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 10,000 or more, more preferably 20,000 or more, and the upper limit is preferably It is desirable that it is 100,000 or less, more preferably 70,000 or less. If the value of the viscosity average molecular weight is too small, the mechanical strength of the polyester resin may be insufficient.If it is too large, the viscosity of the coating solution for forming the photosensitive layer may be too high and the productivity may decrease. is there. In addition, a viscosity average molecular weight can be measured by the method as described in an Example using an Ubbelohde type capillary viscometer etc., for example.

≪Electrophotographic photoreceptor≫
The configuration of the electrophotographic photosensitive member of the present invention will be described below. The electrophotographic photoreceptor of the present invention contains, on a conductive support, the charge transport material represented by the above formula (1) and the polyester resin represented by the formula (2) as a binder resin in the same layer. The structure is not particularly limited as long as the photosensitive layer is provided. In the case where the photosensitive layer of the electrophotographic photosensitive member is a laminated type which will be described later, a charge transporting layer represented by the formula (1), a polyester resin represented by the formula (2), and the like are necessary for the charge transporting layer. Depending on the case, an antioxidant, a leveling agent, and other additives are included. In addition, when the electrophotographic photosensitive layer is a single layer type, which will be described later, in addition to the components used for the charge transport layer of the above-mentioned multilayer photoconductor, a charge generating material and an electron transport material may be used. It is common.

<Conductive support>
There are no particular restrictions on the conductive support, but for example, metal materials such as aluminum, aluminum alloys, stainless steel, copper and nickel, and conductive powders such as metal, carbon and tin oxide can be added to make the conductive material conductive. Mainly used are resin, glass, paper, or the like obtained by depositing or applying the applied resin material or a conductive material such as aluminum, nickel, ITO (indium tin oxide) on the surface. These may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and arbitrary ratios. As a form of the conductive support, a drum form, a sheet form, a belt form or the like is used. Furthermore, a conductive material having an appropriate resistance value may be used on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

Moreover, when using metal materials, such as an aluminum alloy, as an electroconductive support body, you may use, after giving an anodic oxide film. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
The surface of the conductive support may be smooth, or may be roughened by using a special cutting method or performing a polishing treatment. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the conductive support. In order to reduce the cost, it is possible to use the drawing tube as it is without performing the cutting process.

<Underlayer>
An undercoat layer may be provided between the conductive support and the photosensitive layer described later for improving adhesion and blocking properties. As the undercoat layer, a resin or a resin in which particles such as a metal oxide are dispersed is used. The undercoat layer may be a single layer or a plurality of layers.

  Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of the several crystal state may be contained.

  In addition, various particle sizes of metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is preferably 10 nm or more and 100 nm or less, and particularly 10 nm or more and 50 nm or less. preferable. This average primary particle size can be obtained from a TEM photograph or the like.

The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. The binder resin used for the undercoat layer is epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, chloride resin. Cellulose esters such as vinylidene resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacryl resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, nitrocellulose Resin, cellulose ether resin, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, zirconium chelate compound, zirconium The organic zirconium compound alkoxide compounds, titanyl chelate compounds, organic titanyl compounds such as titanium alkoxide compounds include known binder resins such as a silane coupling agent. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.

The use ratio of the inorganic particles to the binder resin used in the undercoat layer can be arbitrarily selected. From the viewpoint of the stability of the dispersion and the coating property, the binder resin is usually 10% by mass or more, It is preferable to use in the range of 500 mass% or less.
The thickness of the undercoat layer is arbitrary as long as the effects of the present invention are not significantly impaired, but the viewpoint of improving the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and coating properties during production of the electrophotographic photosensitive member. Therefore, it is usually 0.01 μm or more, preferably 0.1 μm or more, and usually 30 μm or less, preferably 20 μm or less. A known antioxidant or the like may be mixed in the undercoat layer. For the purpose of preventing image defects, pigment particles, resin particles, and the like may be included.

<Photosensitive layer>
The photosensitive layer is formed on the above-mentioned conductive support (or on the undercoat layer when the above-described undercoat layer is provided). The photosensitive layer is a layer containing a charge transport material represented by the above formula (1) and a polyester resin represented by the formula (2). Including a charge transporting substance of the present invention in the same layer and having a single layer structure in which they are dispersed in a binder resin (hereinafter referred to as “single layer type photosensitive layer” as appropriate) and a charge generating material as a binder Function separation type of laminated structure comprising two or more layers, including a charge generation layer dispersed in a resin and a charge transport material (including the charge transport material of the present invention) dispersed in a binder resin (Hereinafter referred to as “laminated photosensitive layer” as appropriate), but any form may be used.

  In addition, as the laminated photosensitive layer, a charge-generating layer and a charge transport layer are laminated in this order from the conductive support side, and conversely, a charge transport layer and a charge generation layer are formed from the conductive support side. There are reverse laminated photosensitive layers provided in order, and any of them can be adopted, but a forward laminated photosensitive layer that can exhibit the most balanced photoconductivity is preferable.

<Laminated photosensitive layer>
[Charge generation layer]
The charge generation layer of the laminated photosensitive layer (function-separated type photosensitive layer) contains a charge generation material and usually contains a binder resin and other components used as necessary. Such a charge generation layer is prepared, for example, by dissolving or dispersing a charge generation material and a binder resin in a solvent or dispersion medium to prepare a coating solution, and in the case of a sequentially laminated photosensitive layer, this is formed on a conductive support. (If an undercoat layer is provided, it can be obtained on the undercoat layer). In the case of a reverse laminated type photosensitive layer, it can be obtained by coating on a charge transport layer and drying.

  Examples of the charge generation material include inorganic photoconductive materials such as selenium and its alloys, cadmium sulfide, and organic photoconductive materials such as organic pigments. Organic photoconductive materials are preferred, and organic photoconductive materials are particularly preferable. Pigments are preferred. Examples of organic pigments include phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments. . Among these, phthalocyanine pigments or azo pigments are particularly preferable. When organic pigments are used as the charge generating substance, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

When using a phthalocyanine pigment as a charge generation material, specifically, metal such as metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, aluminum, or oxides thereof, halides, Those having each crystal form of coordinated phthalocyanines such as hydroxides and alkoxides, and phthalocyanine dimers using oxygen atoms as bridging atoms are used. Particularly, titanyl phthalocyanines (also known as oxytitanium) such as X-type, τ-type metal-free phthalocyanine, A-type (also known as β-type), B-type (also known as α-type), and D-type (also known as Y-type), which are highly sensitive crystal types Phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, hydroxyindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and type I, type II, etc. The [mu] -oxo-aluminum phthalocyanine dimer is preferred.

  Among these phthalocyanines, A-type (also known as β-type), B-type (also known as α-type), and powder X-ray diffraction angle 2θ (± 0.2 °) are 27.1 ° or 27.3 °. D-type (Y-type) titanyl phthalocyanine, II-type chlorogallium phthalocyanine, V-type hydroxygallium phthalocyanine, hydroxygallium phthalocyanine having the strongest peak at 28.1 °, or 26. Hydroxygallium phthalocyanine having no peak at 2 °, a clear peak at 28.1 °, and a full width at half maximum W of 25.9 ° of 0.1 ° ≦ W ≦ 0.4 ° G-type μ-oxo-gallium phthalocyanine dimer and the like are particularly preferable.

  When a metal-free phthalocyanine compound or a metal-containing phthalocyanine compound is used as the charge generation material, a highly sensitive photoreceptor can be obtained with respect to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm. Further, when an azo pigment such as monoazo, diazo, or trisazo is used, white light, laser light having a wavelength around 660 nm, or laser light having a relatively short wavelength (for example, a wavelength in the range of 380 nm to 500 nm). It is possible to obtain a photoreceptor having sufficient sensitivity to the laser beam).

  The phthalocyanine compound may be a single compound or several mixed or mixed crystal states. As the mixed state in the phthalocyanine compound or crystal state here, those obtained by mixing the respective constituent elements later may be used, or the mixed state in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, crystallization, etc. It may be the one that gave rise to. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known. In order to generate a mixed crystal state, as described in JP-A-10-48859, two types of crystals are mixed, mechanically ground and made amorphous, and then converted into a specific crystal state by solvent treatment. The method of doing is mentioned.

  On the other hand, when an azo pigment is used as a charge generation material, various known azo pigments can be used as long as they have sensitivity to a light source for light input. Trisazo pigments are preferably used. Examples of preferred azo pigments are shown below.

  When the organic pigments exemplified above are used as the charge generation material, one kind may be used alone, or two or more kinds of pigments may be mixed and used. In this case, it is preferable to use a combination of two or more kinds of charge generating materials having spectral sensitivity characteristics in different spectral regions of the visible region and the near red region. Among them, a disazo pigment, a trisazo pigment and a phthalocyanine pigment are preferably used in combination. More preferred.

The binder resin used for the charge generation layer constituting the multilayer photosensitive layer is not particularly limited. For example, polyvinyl butyral resin, polyvinyl formal resin, partially acetalized polyvinyl butyral resin in which part of butyral is modified with formal, acetal, or the like. Polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, modified ether polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, etc. Polyacrylamide resin, polyamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, Vinyl chloride such as zein, vinyl chloride-vinyl acetate copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer -Insulating resin such as vinyl acetate copolymer, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, styrene-alkyd resin, silicon-alkyd resin, phenol-formaldehyde resin, and poly-N-vinylcarbazole , Organic photoconductive polymers such as polyvinyl anthracene and polyvinyl perylene. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.
Specifically, the charge generation layer is prepared by dispersing a charge generation material in a solution obtained by dissolving the above-described binder resin in an organic solvent to prepare a coating solution, which is then formed on a conductive support (when an undercoat layer is provided). Is formed by coating (on the undercoat layer).

  The solvent used for preparing the coating solution is not particularly limited as long as it dissolves the binder resin. For example, saturated aliphatic solvents such as pentane, hexane, octane, and nonane, and aromatics such as toluene, xylene, and anisole. Group solvents, halogenated aromatic solvents such as chlorobenzene, dichlorobenzene, chloronaphthalene, amide solvents such as dimethylformamide, N-methyl-2-pyrrolidone, methanol, ethanol, isopropanol, n-butanol, benzyl alcohol, etc. Alcohol solvents, aliphatic polyhydric alcohols such as glycerin and polyethylene glycol, chain or cyclic ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, 4-methoxy-4-methyl-2-pentanone, methyl formate, ethyl acetate, Acetic acid n-bu Chains such as ester solvents such as benzene, halogenated hydrocarbon solvents such as methylene chloride, chloroform, 1,2-dichloroethane, diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, etc. Or cyclic ether solvents, acetonitrile, dimethyl sulfoxide, sulfolane, aprotic polar solvents such as hexamethylphosphoric triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, triethylenediamine, triethylamine-containing nitrogen Compound, mineral oil such as ligroin, water and the like. Any one of these may be used alone, or two or more of these may be used in combination. In addition, when providing the above-mentioned undercoat layer, what does not melt | dissolve this undercoat layer is preferable.

  In the charge generation layer, the compounding ratio (mass ratio) of the binder resin and the charge generation material is usually 10 parts by mass or more, preferably 30 parts by mass or more, and usually 1000 parts by mass with respect to 100 parts by mass of the binder resin. The range is not more than part by mass, preferably not more than 500 parts by mass. The film thickness of the electrification generation layer is usually in the range of 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material. On the other hand, if the ratio of the charge generating substance is too low, the sensitivity as a photoreceptor may be reduced.

  As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, or a sand mill dispersion method can be used. At this time, it is effective to refine the particles to a particle size in the range of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

<Charge transport layer>
The charge transport layer of the multilayer photoreceptor contains a charge transport material, a binder resin, and other components used as necessary. Specifically, such a charge transport layer is prepared by dissolving or dispersing a charge transport material or the like and a binder resin in a solvent to prepare a coating solution. In addition, in the case of a reverse lamination type photosensitive layer, it can be obtained by coating and drying on a conductive support (on the undercoat layer when an undercoat layer is provided).

  As the charge transport material, the charge transport material represented by the above-described formula (1) is preferable. In addition to the charge transport material represented by the above formula (1), other known charge transport materials may be used in combination. When other charge transport materials are used in combination, the type is not particularly limited, but for example, carbazole derivatives, hydrazone compounds, aromatic amine derivatives, enamine derivatives, butadiene derivatives and those in which a plurality of these derivatives are bonded are preferable.

  In order to exhibit the effect of the charge transport material of the present invention, the ratio of the charge transport material represented by the formula (1) of the present invention to the total charge transport material is usually 10% by weight or more, The amount is preferably 30% by weight or more from the viewpoint of the light attenuation characteristics of the body, more preferably 50% by weight or more, and particularly preferably 70% by weight or more from the viewpoint of the high-speed response of the electrophotographic photosensitive member.

  As the binder resin, a polyester resin represented by the above formula (2) is used. The polyester resin represented by the formula (2) may be used alone, but may be used by mixing with other resins as long as the function is not impaired. Examples of binder resins that may be used as a mixture include butadiene resins, styrene resins, vinyl acetate resins, vinyl chloride resins, acrylic ester resins, methacrylic ester resins, vinyl alcohol resins, and ethyl vinyl ethers. Copolymers and copolymers, polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicon resin, silicon-alkyd resin, poly-N-vinylcarbazole resin Etc. Among these, polycarbonate resin is preferable. These binder resins can also be used after being crosslinked by heat, light or the like using an appropriate curing agent.

  The ratio between the binder resin and the charge transport material is 10 parts by mass or more of the charge transport material with respect to 100 parts by mass of the binder resin. Among these, 20 parts by mass or more is preferable from the viewpoint of residual potential reduction, and more preferably 30 parts by mass or more from the viewpoint of stability and charge mobility when repeatedly used. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, the charge transport material is usually used at a ratio of 120 parts by mass or less. Among these, 100 parts by mass or less is preferable from the viewpoint of compatibility between the charge transport material and the binder resin, 90 parts by mass or less is more preferable from the viewpoint of printing durability, and 80 parts by mass or less is most preferable from the viewpoint of scratch resistance.

  The reason why the combination of the charge transport material represented by the formula (1) and the polyester resin represented by the formula (2) is specifically good is not clear, but in general, the polyester resin is compared with the polycarbonate resin. Thus, the polarity is strong, and the polarity site tends to be a trap for charge transport. Therefore, in order to develop a sufficient charge transport function in such a state, not only the electron donating property of the charge transport material is sufficiently increased by alkoxy group substitution or the like, that is, the ionization potential is sufficiently small. By making the molecule a uniaxially extending shape close to symmetry, the charge transportability in the molecule, that is, the uniform spread without distortion of the conjugated electron cloud is ensured, and the adjacent charge transport material It is presumed that it is important to increase the probability of overlapping with the conjugated electron cloud. From this point of view, the charge transport material represented by the formula (1) of the present application effectively has an alkoxy group at the center of the molecule, and a conjugated system moderately spreads symmetrically from there. It is thought that.

  The film thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, on the other hand, usually 50 μm or less, preferably 45 μm or less, from the viewpoints of long life, image stability, and charging stability. Furthermore, in the range of 30 μm or less, 25 μm or less is most suitably used from the viewpoint of increasing the resolution.

<Single layer type photosensitive layer>
The single-layer type photosensitive layer is formed using a binder resin in order to ensure film strength, in the same manner as the charge transport layer of the multilayer photoconductor, in addition to the charge generation material and the charge transport material. Specifically, a charge generation material, a charge transport material, and various binder resins are dissolved or dispersed in a solvent to prepare a coating solution, and on a conductive support (or an undercoat layer when an undercoat layer is provided). It can be obtained by coating and drying.

The types of the charge transport material and the binder resin and the use ratios thereof are the same as those described for the charge transport layer of the multilayer photoreceptor. A charge generation material is further dispersed in a charge transport medium comprising these charge transport materials and a binder resin.
As the charge generation material, the same materials as those described for the charge generation layer of the multilayer photoreceptor can be used. However, in the case of a photosensitive layer of a single layer type photoreceptor, it is necessary to sufficiently reduce the particle size of the charge generating material. Specifically, the range is usually 1 μm or less, preferably 0.5 μm or less.

  In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. It is 30 mass parts or less, Preferably it is set as the range of 10 mass parts or less. The film thickness of the single-layer type photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less.

<Other additives>
For the purpose of improving film-forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, etc., in both the photosensitive layer and each layer constituting it, both in the multilayer type photosensitive member and the single layer type photosensitive member. Additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents may be contained.

<Other functional layers>
Further, in both the laminated type photoreceptor and the single layer type photoreceptor, the photosensitive layer formed by the above procedure may be the uppermost layer, that is, the surface layer, but another layer may be provided on the photosensitive layer and used as the surface layer. Good. For example, a protective layer may be provided for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to discharge products generated from a charger or the like.

The electrical resistance of the protective layer is usually in the range of 10 ⁹ Ω · cm to 10 ¹⁴ Ω · cm. When the electric resistance is higher than the range, the residual potential is increased, resulting in an image with much fogging. On the other hand, when the electric resistance is lower than the range, the image is blurred and the resolution is reduced. Further, the protective layer must be configured so as not to substantially prevent transmission of light irradiated during image exposure.

  Further, for the purpose of reducing the frictional resistance and wear on the surface of the photoconductor, and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper, etc., the surface layer is made of fluorine resin, silicon resin, polyethylene resin, or the like. You may contain the particle | grains which consist of these resin, and the particle | grains of an inorganic compound. Alternatively, a layer containing these resins and particles may be newly formed as a surface layer.

<Universal hardness, elastic deformation rate>
The universal hardness of the layer containing the charge transport material represented by the formula (1) and the polyester resin having the structural unit represented by the formula (2) is usually 150 N / mm ² or more and 170 N / mm ^2. It is preferable that it is above, and it is usually preferable that it is 250 N / mm ² or less and 220 N / mm ² or less. If it is 150 N / mm ² or less, abnormal noise due to blade chatter is likely to be generated, and the amount of plastic deformation is increased. Therefore, the problem of increased adhesion of foreign matter that leads to image defects such as filming is likely to occur. If it is 250 N / mm ² or more, since the amount of elastic deformation is small, the surface becomes fragile and is easily damaged by hard foreign matter.

  The elastic deformation rate of the outermost surface layer containing the polyester resin represented by the formula (2) is preferably 40% or more from the viewpoint of wear resistance, and 43% or more from the viewpoint of preventing toner adhesion. And is most preferably 46% or more. In order to maintain a high elastic deformation rate, the polyester resin represented by the formula (2) is preferably polyarylate, which is a wholly aromatic polyester. The elastic deformation rate is measured under an environment of a temperature of 25 ° C. and a relative humidity of 50% using a Fischer micro hardness tester FISCHERSCOPE H100C (or HM2000 having equivalent performance). For the measurement, a Vickers square pyramid diamond indenter having a facing angle of 136 ° is used.

<Method for forming each layer>
Each layer constituting the above-described photoreceptor is formed by dip coating, spray coating, nozzle coating, bar coating, roll coating, blade coating on a conductive support obtained by dissolving or dispersing a substance to be contained in a solvent. It is formed by repeating a coating / drying step sequentially for each layer by a known method such as coating.

  There are no particular restrictions on the solvent or dispersion medium used for the preparation of the coating solution, but specific examples include alcohols such as methanol, ethanol, propanol and 2-methoxyethanol, tetrahydrofuran, 1,4-dioxane, dimethoxyethane and the like. Ethers, esters such as methyl formate and ethyl acetate, acetone, methyl ethyl ketone, cyclohexanone, ketones such as 4-methoxy-4-methyl-2-pentanone, aromatic hydrocarbons such as benzene, toluene, xylene, dichloromethane, Chlorinated hydrocarbons such as chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, n-butylamine, isopropanolamine, Diethyl Min, triethanolamine, ethylenediamine, nitrogen-containing compounds such as triethylenediamine, acetonitrile, N- methylpyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and kinds.

The amount of the solvent or the dispersion medium used is not particularly limited, but considering the purpose of each layer and the properties of the selected solvent / dispersion medium, it is appropriately determined so that the physical properties such as the solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust.
For example, in the case of a charge transport layer of a single layer type photoreceptor or a function separation type photoreceptor, the solid content concentration of the coating solution is usually 5% by mass or more, preferably 10% by mass or more, and usually 40% by mass or less. The range is preferably 35% by mass or less. In addition, the viscosity of the coating solution is usually 10 mPa · s or higher, preferably 50 mPa · s or higher, and usually 500 mPa · s or lower, preferably 400 mPa · s or lower, at the temperature during use.

  In the case of a charge generation layer of a multilayer photoreceptor, the solid content concentration of the coating solution is usually 0.1% by mass or more, preferably 1% by mass or more, and usually 15% by mass or less, preferably 10% by mass. % Or less. In addition, the viscosity of the coating solution is usually 0.01 mPa · s or higher, preferably 0.1 mPa · s or higher, and usually 20 mPa · s or lower, preferably 10 mPa · s or lower, at the temperature during use.

Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used.
The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. Further, the heating temperature may be constant, or heating may be performed while changing the temperature during drying.

≪Image forming device≫
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention (an image forming apparatus of the present invention) will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

As shown in FIG. 1, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, and a developing device 4, and further, a transfer device 5, a cleaning device 6, and a fixing device as necessary. A device 7 is provided.
The electrophotographic photoreceptor 1 is not particularly limited as long as it is the above-described electrophotographic photoreceptor of the present invention, but in FIG. 1, as an example, a drum in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. The photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged along the outer peripheral surface of the electrophotographic photoreceptor 1.

  The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. As the charging device, a corona charging device such as a corotron or a scorotron, a direct charging device (contact type charging device) for charging a direct charging member to which a voltage is applied by contacting the photosensitive member surface, and the like are often used. Examples of the direct charging device include a charging roller and a charging brush. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2. As the direct charging means, either charging with air discharge or injection charging without air discharge is possible. Moreover, as a voltage applied at the time of charging, it is possible to use only a direct current voltage or to superimpose an alternating current on a direct current.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, if exposure is performed with monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength of 600 nm to 700 nm, slightly shorter wavelength, monochromatic light with a wavelength of 380 nm to 500 nm, or the like. Good.

  The type of the developing device 4 is not particularly limited, and an arbitrary device such as a dry development method such as cascade development, one-component insulating toner development, one-component conductive toner development, or two-component magnetic brush development, or a wet development method is used. be able to. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. This replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

  The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicon resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.

The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

The regulating member 45 is formed of a resin blade such as silicon resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such a metal blade with a resin. The regulating member 45 contacts the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 5 to 500 g / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.
The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.

The type of the toner T is arbitrary, and in addition to the powdery toner, a polymerized toner using a suspension polymerization method, an emulsion polymerization method or the like can be used. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.
The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

  There is no restriction | limiting in particular about the cleaning apparatus 6, Arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner. However, when there is little or almost no toner remaining on the surface of the photoreceptor, the cleaning device 6 may be omitted.

  The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. The upper and lower fixing members 71 and 72 are known heat fixings such as a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, or a fixing sheet. A member can be used. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicon oil in order to improve releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P.
The type of the fixing device is not particularly limited, and a fixing device of an arbitrary method such as heat roller fixing, flash fixing, oven fixing, pressure fixing, or the like can be provided.

  In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.

Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.
The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.

  When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.
In addition to the above-described configuration, the image forming apparatus may be configured to perform, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.
The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.

  The electrophotographic photosensitive member 1 is combined with one or more of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6, and the fixing device 7 to form an integrated cartridge ( The electrophotographic photosensitive member cartridge may be configured to be detachable from the main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In this case, for example, when the electrophotographic photosensitive member 1 and other members are deteriorated, the electrophotographic photosensitive member cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic photosensitive member cartridge is mounted on the main body of the image forming apparatus. This facilitates maintenance and management of the image forming apparatus.

Example 1
<Electrophotographic photoreceptor production method>
(Formation of undercoat layer)
The undercoat layer dispersion was produced as follows. High-speed fluidized mixing of rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) Disperse the surface-treated titanium oxide obtained by mixing in a kneading machine (“SMG300” manufactured by Kawata Co., Ltd.) and mixing at high speed at a rotational peripheral speed of 34.5 m / sec using a ball mill of methanol / 1-propanol. Thus, a dispersion slurry of hydrophobized titanium oxide was obtained. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [
Compound represented by the following formula (B)] / hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid Stirring while heating the copolyamide pellets with a composition molar ratio of [compound represented by the following formula (E)] of 75% / 9.5% / 3% / 9.5% / 3%, After mixing and dissolving the polyamide pellets, ultrasonic dispersion treatment is performed, so that the weight ratio of methanol / 1-propanol / toluene is 7/1/2, and the hydrophobically treated titanium oxide / copolymerized polyamide is weight ratio. A subbing layer dispersion containing a solid content of 18.0% and containing 3/1 was obtained.

  The undercoat layer dispersion prepared as described above was cut on the surface of a tube-shaped conductive support made of aluminum alloy (3003 material) having a diameter of 30 mm, a length of 260.5 mm, and a thickness of 0.75 mm. By dip coating, coating was performed such that the film thickness after drying (air drying) was 1.25 μm to form an undercoat layer.

(Formation of charge generation layer)
Oxytitanium phthalocyanine crystal as a charge generating substance (as shown in FIG. 2, the main diffraction peak is 27.2 ° at the black angle (2θ ± 0.2 °) in the X-ray diffraction spectrum for CuKα characteristic X-ray) Was used. Using 20 parts by weight of this oxytitanium phthalocyanine crystal, this was mixed with 280 parts by weight of 1,2-dimethoxyethane, pulverized with a sand grind mill for 2 hours, and subjected to atomization dispersion treatment to obtain a refined treatment liquid. . In addition, a mixture of 253 parts by weight of 1,2-dimethoxyethane and 85 parts by weight of 4-methoxy-4-methyl-2-pentanone was added to polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denkabutyral” # 6000C) 10 parts by weight was dissolved to prepare a binder liquid.

A charge generating layer coating liquid was prepared by mixing the above-described atomization treatment liquid obtained by the atomization dispersion treatment, the above-described binder liquid, and 230 parts by weight of 1,2-dimethoxyethane.
This charge generation layer coating solution is dip-coated on the undercoat layer on the conductive support so that the film thickness after drying (air drying) is 0.3 μm and dried to form a charge generation layer. did.

(Formation of charge transport layer)
As a binder resin, 100 parts by weight of polyarylate resin (Mv = 43,000) composed of a structural unit represented by the following formula PE-1 obtained by the production method described in JP-A-2006-053549, charge transport As a substance, 50 parts by weight of the CT-2 obtained by the production method described in JP-A-2008-74714, an antioxidant having a structure of the following formula (AOX1) (trade name, manufactured by Ciba Specialty Chemicals) IRGANOX 1076) 8 parts by weight and 0.03 parts by weight of silicone oil as a leveling agent were dissolved in 640 parts by weight of a tetrahydrofuran / toluene (weight ratio 8/2) mixed solvent to prepare a charge transport layer coating solution.

  The obtained coating solution for charge transport layer was applied onto the above-described charge generation layer so that the film thickness after drying was 25 μm to obtain an electrophotographic photosensitive member having a laminated photosensitive layer. Drying was performed at 125 ° C. for 25 minutes.

<Evaluation of electrical characteristics of electrophotographic photoreceptor>
An electrophotographic photosensitive member manufactured as described above is produced by an electrophotographic characteristic evaluation apparatus manufactured in accordance with the standard of the Electrophotographic Society ("Basic and Application of Secondary Electrophotographic Technology", edited by Electrophotographic Society, Corona, pages 404-405) The electrical characteristics were evaluated by carrying out a cycle of charging, exposure, potential measurement, and static elimination according to the following procedure.

Under the two conditions of a temperature of 25 ° C./humidity of 50% (referred to as NN) and a temperature of 5 ° C./humidity of 10% (referred to as LL), the photosensitive member is charged so that the initial surface potential is −700 V, and halogenated. The lamp light was irradiated with monochromatic light of 780 nm with an interference filter, and the irradiation energy (half exposure energy) when the surface potential was −350 V was measured as sensitivity (unit: μJ / cm ² ). Further, the surface potential (unit: −V) after the photoconductor was charged so that the initial surface potential was −700 V and measured after exposure with an irradiation energy of 0.55 μJ / cm ² was the exposed portion potential (VL). did. At this time, the time required for the exposure-potential measurement was 100 ms. The measurement results are shown in Table-1.

<Measurement of surface hardness and elastic deformation rate of photoreceptor>
The universal hardness of the surface of the photoconductor was measured in an environment of a temperature of 25 ° C. and a relative humidity of 50% using a micro hardness tester FISCHERSCOPE H100C manufactured by Fischer. The universal hardness value is a value obtained when the indentation is pushed down to an indentation load of 5 mN, and is a value defined by the following formula from the indentation depth at that time. In the measurement in this region, the influence of the hardness of the substrate (aluminum tube) can be eliminated.

Universal hardness (N / mm ² ) = Test load (N) / Vickers indenter surface area under test load (mm ² )
Similarly to the above, the elastic deformation rate of the photoreceptor was measured using a microhardness meter FISHERSCOPE H100C manufactured by Fischer under an environment of a temperature of 25 ° C. and a relative humidity of 50%. For the measurement, a Vickers square pyramid diamond indenter having a facing angle of 136 ° is used. The measurement conditions are set as follows, the load applied to the indenter and the indentation depth under the load are continuously read, and profiles as shown in FIG. 3 plotted on the Y axis and the X axis are obtained.

・ Measurement conditions Maximum indentation load 5mN
Time required for loading 10 seconds Time required for unloading 10 seconds The elastic deformation rate is a value defined by the following formula, and is the ratio of the work that the membrane performs due to elasticity during unloading with respect to the total work required for indentation. is there.

Elastic deformation rate (%) = (We / Wt) × 100
In the above formula, the total work Wt (nJ) indicates the area surrounded by A-B-D-A in FIG. 3, and the elastic deformation work We (nJ) is the area surrounded by C-B-D-C. Indicates. As the elastic deformation rate is larger, the deformation with respect to the load is less likely to remain, and when the elastic deformation rate is 100, it means that no deformation remains.
The measurement results of universal hardness and elastic deformation rate are shown in Table-2.

<Image test>
The above-mentioned electrophotographic photosensitive member is mounted on a photosensitive cartridge of a tandem full color printer LaserJet 4650 manufactured by Hewlett-Packard Co., and 10,000 sheets are continuously printed at a temperature of 25 ° C. and a relative humidity of 50% at a printing rate of 5%. , Image density (whether the density is sufficient), presence / absence of noise from the cleaning blade, presence / absence of cleaning failure, degree of toner adhesion (filming) on the photoreceptor, presence / absence of image memory, gas resistance (Image blurring, white spots, etc.) were examined. The results are shown in Table-2.

Example 2
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following PE-2 (Mv = 40,000) was used instead of the binder resin PE-1 in Example 1. The results are shown in Table-1 and Table-2.

Example 3
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that PE-3 (Mv = 30,000) was used instead of the binder resin PE-1 in Example 1. The results are shown in Table-1 and Table-2.

Example 4
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that CT-4 was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Example 5
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that CT-10 was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Example 6
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the above CT-16 was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Example 7
A photoconductor was prepared in the same manner as in Example 1 except that the isomer mixture of CT-2 and CT-23 (mixing ratio 90:10) was used instead of the charge transport material CT-2 in Example 1. evaluated. The results are shown in Table-1 and Table-2.

Example 8
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that CT-1 was used in place of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 1
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following PC-1 (Mv = 40,000) was used in place of the binder resin PE-1 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 2
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following PC-2 (a: b = 50: 50, Mv = 30,000) was used instead of the binder resin PE-1 in Example 1. did. The results are shown in Table-1 and Table-2.

Comparative Example 3
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following PC-3 (Mv = 30,000) was used instead of the binder resin PE-1 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 4
Example 1 was used except that the following PE-4 (a: b: c: d = 27: 25: 23: 25, Mv = 21,000) was used in place of the binder resin PE-1 of Example 1. A photoreceptor was prepared and evaluated in the same manner as described above. The results are shown in Table-1 and Table-2.

Comparative Example 5
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following CT-A was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 6
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following CT-B was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 7
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following CT-C was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 8
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following CT-D was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 9
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following CT-E was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 10
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following CT-F was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 11
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following CT-G was used instead of the charge transport material CT-2 in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 12
A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the following CT-H was used instead of the charge transport material CT-2 in Example 1. The results are shown in Tables 1 and 2.

  From the above results, when the charge transport material of the present invention and the binder resin were used, the exposure potential was sufficiently lowered, and there was no deposit such as filming, abnormal noise generation, image defects such as image memory, and the like. It can be seen that a photoreceptor is obtained. On the other hand, in Comparative Examples 1 and 2 using a polycarbonate resin, although the exposure potential was sufficiently lowered, the filming was remarkably generated with a low elastic deformation rate, and the image was unusable and became apparent. In Comparative Example 3, the hardness is too high, and the surface of the photoreceptor is damaged. In Comparative Example 4, the elastic deformation rate was too low due to the polyester resin, and filming occurred. In addition, all of the charge transport materials CT-A to G used in the comparative examples had a large exposure potential in combination with the polyarylate resin, and had a low image density and an unusable level in practical use. In addition, when VL is large under the NN condition, it indicates that the spread of the conjugated system of the charge transport material and the ionization potential are incompatible with the polyester resin of the present application, and when VL becomes large under the LL condition, in addition to that, the mobility Is insufficient. In Comparative Example 12, although the electrical characteristics were good, the surface hardness was too low and abnormal noise was generated.

1 Photoconductor (Electrophotographic photoconductor)
2 Charging device (charging roller; charging unit)
3 Exposure equipment (exposure section)
4 Development device (development unit)
DESCRIPTION OF SYMBOLS 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Control member 71 Upper fixing member (fixing roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper (paper, medium)

Claims (5)

In an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, a polyester having a charge transport material represented by the following formula (1) and a structural unit represented by the following formula (2) in the photosensitive layer An electrophotographic photoreceptor comprising a resin.

(In the formula (1), Ar ¹ is an aryl group having at least an alkoxy group as a substituent, Ar ² and Ar ³ are each independently an arylene group optionally having an alkyl group, and Ar ^{4 to} Ar ⁷ are Each independently represents an aryl group optionally having an alkyl group or an alkoxy group, Ar ⁴ and Ar ⁵ , Ar ⁶ and Ar ⁷ may be bonded to each other, provided that the substituents are bonded to each other; And may form a ring.)

(In formula (2), Ar ^{8 to} Ar ¹¹ each independently represents an arylene group which may have a substituent, X represents a single bond, an oxygen atom, a sulfur atom, or an alkylene group. M represents 0. And represents an integer of 2 or less, and Y represents a single bond, an oxygen atom, a sulfur atom, or an alkylene group. The electrophotographic photosensitive member according to claim 1, wherein Ar ^{4 to} Ar ⁷ are each independently an aryl group having an alkyl group having 10 or less carbon atoms. The universal hardness of the layer containing the charge transport material represented by the formula (1) and the polyester resin having the structural unit represented by the formula (2) is 170 N / mm ² or more and 220 N / mm ² or less. 3. The electrophotographic photosensitive member according to claim 1, wherein the elastic deformation rate is 43% or more.   The electrophotographic photosensitive member according to any one of claims 1 to 3, a charging device that charges the electrophotographic photosensitive member, and an exposure that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image. An electrophotographic photosensitive member cartridge comprising: an apparatus; and at least one selected from the group consisting of a developing device for developing an electrostatic latent image formed on the electrophotographic photosensitive member.   The electrophotographic photosensitive member according to claim 1, a charging device that charges the electrophotographic photosensitive member, and an exposure device that forms an electrostatic latent image by exposing the charged electrophotographic photosensitive member. An image forming apparatus comprising: a developing device that develops the electrostatic latent image formed on the electrophotographic photosensitive member.

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