JP6354184B2 - Electrophotographic photosensitive member, electrophotographic process cartridge, and image forming apparatus - Google Patents

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, and in particular, the shape of a chemical toner is often close to a sphere, so that when the toner remaining on the photoreceptor is cleaned with a blade, the toner slips through. 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, 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 that can meet the demand for improvement (see Patent Documents 1 to 5).

  In recent years, there has been a demand for further downsizing of an image forming apparatus from the viewpoint of space saving. In this case, in order to realize the downsizing of the image forming apparatus, a small-diameter type such as 30 mmφ is used as the photoreceptor (see Patent Document 6). When the outer diameter of the photosensitive drum is small, a large curvature is applied to the thermal contraction when the coated photosensitive layer is dried, which is a disadvantageous direction from the viewpoint of adhesion between the photosensitive layer and the support.

  Furthermore, with the trend toward miniaturization and speeding up of electrophotographic apparatuses, the diameter of the photoreceptor is reduced, and further improvement in electrical response (quick reduction of the surface potential of the photoreceptor 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, many studies have been made on charge transport materials in which a π-electron system is extended to a triphenylamine skeleton or a tetraphenylbenzidine skeleton with a styryl group or the like (see Patent Documents 7 to 8).

In particular, in recent years, improvement in abrasion resistance has been desired. As one solution, charge transport using a binder resin excellent in abrasion resistance for the photosensitive layer and extending the electro-electron system is used. Although there is a method of reducing the content of the substance and not damaging the performance of the binder resin as much as possible, attention has not been paid to the adhesion between layers (Patent Document 9).
On the other hand, various materials such as phthalocyanine pigments, squalium dyes, azo pigments, and perylene pigments have been studied as charge generation materials in electrophotographic photoreceptors, and electrophotographic photoreceptors having high sensitivity and excellent repetitive characteristics are provided. In order to achieve this, there is described a method for producing a pigment dispersion for producing an electrophotographic photosensitive member in which 1 to 40% by mass of the binder of the total amount of the charge generating material pigment is dissolved (see Patent Document 10). .

JP 50-098332 A JP 59-184251 Japanese Patent Laid-Open No. 03-006567 Japanese Patent Laid-Open No. 10-20514 JP 2008-293006 A JP 2012-22312 A Japanese Patent No. 2940502 JP 2008-70591 A JP 2011-248250 A JP 2002-244318 A

  However, according to the study of the present inventors, the techniques described in Patent Documents 1 to 10 show improvements in electrical characteristics, wear resistance, etc., but the internal stress increases because the shrinkage of the photosensitive layer increases. It has been found that sufficient performance may not be obtained in the adhesion of the photosensitive layer, and peeling occurs when the adhesion to the substrate is insufficient. On the other hand, when the binder resin ratio of the charge generation layer is increased to improve the adhesion, the abundance of the charge generation material is lowered, and the sensitivity is lowered. Furthermore, if the content of the charge transport material is reduced to improve the printing durability, the charge transport ability is lowered. As described above, the increase in the binder resin ratio in the charge generation layer and the decrease in the content of the charge transport material cause deterioration of the characteristics of the photoreceptor.

  The present invention has been made in view of the above problems, and is a binder excellent in wear resistance to practical loads, excellent in electrical characteristics while maintaining high mechanical strength, and excellent in adhesion to a substrate and an adjacent layer. An object of the present invention is to provide an electrophotographic photoreceptor containing a resin.

  As a result of intensive studies on an electrophotographic photosensitive member that can solve the above-described problems, the present inventors have found that in an electrophotographic photosensitive member having at least a charge generation layer and a charge transport layer on a conductive support, the charge generation layer Includes a charge generation material and a binder resin, the mass ratio wr of the charge generation material to the total binder resin is 0.4 ≦ wr ≦ 1.4, the binder resin is a polyvinyl acetal resin, and the charge transport layer is A charge transport material, and the content of the charge transport material is 32 to 50 parts by weight with respect to 100 parts by weight of the total binder resin in the charge transport layer, and the HOMO energy level E_homo and polarization of the charge transport material The inventors have found that the above-mentioned problems can be solved by satisfying the specific rate α, and have arrived at the present invention based on such knowledge.

＜２＞
前記電荷輸送層のバインダ樹脂が、ジオール成分として下記一般式（I）で表される構
造を有し、且つジカルボン酸成分として下記一般式（II）で表される構造を有するポリア
リレート樹脂であることを特徴とする＜１＞に記載の電子写真感光体。 That is, the gist of the present invention resides in the following <1> to <5>.
<1>
In an electrophotographic photosensitive member having at least a charge generation layer and a charge transport layer on a conductive support, the charge generation layer contains a charge generation material and a polyvinyl acetal resin as a binder resin, and all binder resins in the charge generation layer The mass ratio of the charge generating material to [the charge generating material / total binder resin] wr is 0.4 ≦ wr ≦ 1.4, and the charge transport layer includes the charge transport material and the binder resin, and the total charge transport The content of the substance is all binder resin 10 in the charge transport layer.
32 to 50 parts by mass with respect to 0 part by mass, and the charge transport material has the following structural formula CT-2 and
An electrophotographic photoreceptor , which is at least one compound of the structural formula CT-3 .

<2>
The binder resin of the charge transport layer is a polyarylate resin having a structure represented by the following general formula (I) as a diol component and a structure represented by the following general formula (II) as a dicarboxylic acid component <1> The electrophotographic photosensitive member according to <1>.

(In Formula (I), Ar ¹ and Ar ² each independently represent an arylene group optionally having a substituent, X represents a single bond or a divalent linking group, and in Formula (II), , Ar ³ and Ar ⁴ each independently represent an optionally substituted arylene group, Y represents each independently a single bond or a divalent linking group, and k represents an integer of 0 or more. .)
< 3 >
Wherein the conductive support is subjected to anodic oxidation treatment and sealing treatment <1> The
Is the electrophotographic photosensitive member according to < 2 >.
< 4 >
<1> to < 3 > The electrophotographic photosensitive member according to any one of the above, a charging unit for charging the electrophotographic photosensitive member, and exposing the charged electrophotographic photosensitive member to image exposure to form an electrostatic latent image. An electrophotographic cartridge comprising: at least one of an image exposure unit to be formed, a developing unit for developing the electrostatic latent image with toner, and a transfer unit for transferring the toner to a transfer target.
< 5 >
<1> to < 3 > The electrophotographic photosensitive member according to any one of the above, a charging unit that charges the electrophotographic photosensitive member, and an electrostatic latent image is formed by exposing the charged electrophotographic photosensitive member. An exposure unit; a developing unit that develops the electrostatic latent image with toner; a transfer unit that transfers the toner to a transfer target; and a fixing unit that fixes the toner transferred to the transfer target. An image forming apparatus as a feature.

  According to the present invention, an electrophotographic photoreceptor excellent not only in abrasion resistance and filming resistance but also in electrical characteristics and adhesion between the photosensitive layer and the substrate or adjacent layer can be obtained.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention.

  Hereinafter, the present invention will be described. However, the present invention is not limited to the following specific embodiments, and can be arbitrarily modified without departing from the spirit of the present invention.

[1. Electrophotographic photoreceptor]
The electrophotographic photoreceptor of the present invention has a charge generation layer and a charge transport layer on a conductive support, the charge generation layer contains a charge generation material and a binder resin, and the binder resin is polyvinyl acetal. The charge transporting layer contains a polyarylate resin.

[1-1. Conductive support]
As the conductive support used in the photoreceptor of the present invention, for example, a metal material such as aluminum, aluminum alloy, stainless steel, copper, or nickel is mainly used. As the conductive support, one type of material may be used alone, or two or more types of materials may be used in any ratio and combination. Other material components to be combined include resin materials that have been given conductivity by adding conductive powders such as metal, carbon, and tin oxide; conductive materials such as aluminum, nickel, and ITO (indium tin oxide) Examples thereof include resin, glass, paper; and the like deposited or coated on the surface.

For example, a drum shape, a sheet shape, a belt shape, or the like is used. From the viewpoint of maximizing the effect that the adhesiveness of the present invention is good, the internal stress of the photosensitive layer works greatly. In addition, a drum shape that tends to have insufficient adhesion between the photosensitive layer and the conductive support is preferable.
In the present invention, it is preferable to use a conductive support having an anodized film on the surface of the conductive support from the viewpoint of adhesiveness. When applying an anodized film, it is preferable to perform a sealing treatment by a known method. As an anodizing method, for example, an anodizing film is formed by anodizing in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, etc. Anodizing of gives better results.

In the case of anodization in sulfuric acid, various conditions are arbitrary as long as the desired anodizing treatment can be performed. Among them, the sulfuric acid concentration is usually 100 g / L or more, and usually 300 g / L or less, and the dissolved aluminum concentration is usually 2 g. / L or more, usually 15 g / L or less, the liquid temperature is usually 15 ° C. or more, usually 30 ° C. or less, the electrolysis voltage is usually 10 V or more, and usually 20 V or less, and the current density is usually 0.5 A / dm ^2. In addition, 2 A / dm ² or less is usually desirable.

  It is preferable to perform a sealing treatment on the anodic oxide film thus formed. The sealing treatment can be performed by a known method. As the sealing treatment method, for example, a low-temperature sealing treatment in which the sealing treatment is immersed in an aqueous solution (nickel fluoride aqueous solution) containing nickel fluoride as a main component, or A high temperature sealing treatment in which the component is immersed in an aqueous solution containing nickel acetate (nickel acetate aqueous solution) is preferred.

The concentration of nickel fluoride in the nickel fluoride aqueous solution used in the case of the above low-temperature sealing treatment is arbitrary as long as the effect of the present invention is not significantly impaired. More favorable results can be obtained when used at the following concentrations.
Moreover, in order to advance a sealing process smoothly, process temperature is 25 degreeC or more normally, Preferably it is 30 degreeC or more, and the upper limit is 40 degrees C or less normally, Preferably it is 35 degrees C or less.

The pH of the aqueous nickel fluoride solution is usually 4.5 or higher, preferably 5.5 or higher, and the upper limit is usually 6.5 or lower, preferably 6.0 or lower. As the pH regulator, any known substance can be used. For example, oxalic acid, boric acid, formic acid, acetic acid, sodium hydroxide, sodium acetate, aqueous ammonia and the like can be used.
In addition, a pH adjuster may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

  The treatment time is preferably within a range of usually 1 minute or more and usually 3 minutes or less per 1 μm of film thickness. In order to further improve the physical properties of the film, for example, cobalt fluoride, cobalt acetate, nickel sulfate, a surfactant and the like may be mixed in the nickel fluoride aqueous solution. After the above treatment, the low-temperature sealing treatment can be completed by washing with water, drying, or the like, if necessary.

  Moreover, as a sealing agent in the case of said high temperature sealing processing, metal salt aqueous solution, such as nickel acetate, cobalt acetate, lead acetate, nickel acetate-cobalt, barium nitrate, can be used, especially nickel acetate. It is preferable to use an aqueous solution. When using a nickel acetate aqueous solution, the nickel acetate concentration in the nickel acetate aqueous solution is preferably 5 g / L or more and usually 20 g / L or less.

  Furthermore, the treatment temperature is usually 80 ° C. or higher, preferably 90 ° C. or higher, and the upper limit is usually 100 ° C. or lower, preferably 98 ° C. or lower. Further, the pH of the aqueous nickel acetate solution is preferably in the range of usually 5.0 or more and usually 6.0 or less. As the pH regulator, aqueous ammonia, sodium acetate, or the like can be used. In addition, a pH adjuster may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

The treatment time is usually 10 minutes or longer, preferably 20 minutes or longer. In this case, sodium acetate, organic carboxylic acid, anionic and nonionic surfactants may be mixed in the nickel acetate aqueous solution in order to improve the film properties.
After the above treatment, the high temperature sealing treatment can be completed by washing with water, drying or the like, if necessary.

When the average film thickness is thick, strong sealing conditions may be required due to high concentration of the sealing liquid and high temperature / long time processing. Therefore, productivity is deteriorated and surface defects such as stains, dirt, and dusting are easily generated on the coating surface. From such a viewpoint, the average film thickness of the anodized film is usually 20 μm or less, preferably 7 μm or less.
The surface of the conductive support may be smooth, or may be roughened by using a special cutting method or polishing. 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 cutting. Especially when using a non-cutting aluminum support such as drawing, impact processing, and ironing, the process eliminates dirt, foreign matter, and other small scratches on the surface, resulting in a uniform and clean support. Therefore, it is preferable.

[1-2. Undercoat layer]
An undercoat layer may be provided between the conductive support and the photosensitive layer described below for the purpose of improving adhesion and blocking properties. From the viewpoint of improvement, it is preferable not to provide an undercoat layer. 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 a 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.

[1-3. Photosensitive layer]
As the constitution of the photosensitive layer, any constitution applicable to a known electrophotographic photosensitive member can be adopted, but taking into consideration the mechanical properties, electrical characteristics, manufacturing stability, etc. Of these, a laminated electrophotographic photoreceptor is preferred. In particular, a sequential lamination type photoreceptor in which a charge generation layer and a charge transport layer are laminated in this order on a conductive support is more preferable.

[1-3-1. Binder resin]
Examples of the binder resin used for the photosensitive layer include polymers and copolymers of vinyl compounds such as butadiene resin, styrene resin, vinyl acetate resin, vinyl chloride resin, acrylic ester resin, methacrylic ester resin, vinyl alcohol resin, and ethyl vinyl ether. Polymer, polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyester resin, polyarylate resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicone resin, silicone-alkyd resin, poly-N -Vinyl carbazole resin etc. are mentioned. These resins may be modified with a silicon reagent or the like. Of the binder resins, polyarylate resin or polycarbonate resin is preferable. In addition, binder resin may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

  The viscosity average molecular weight of the binder resin is arbitrary as long as the effects of the present invention are not significantly impaired, but preferably 10,000 or more, more preferably 20000 or more, and the upper limit thereof is preferably 150,000 or less, more preferably 100,000 or less. It is desirable to be. If the value of the viscosity average molecular weight is too small, the mechanical strength of the binder resin may be insufficient, and 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.

[1-3-2. Polyarylate resin]
The photosensitive layer in the electrophotographic photoreceptor of the present invention preferably contains a polyarylate resin. As the polyarylate resin, any known one can be used. Among them, the diol component has a structure represented by the following general formula (I), and the dicarboxylic acid component is represented by the following general formula (II). It is preferable to use a polyarylate resin having the structure represented.

In the formula (I), Ar ¹ and Ar ² each independently represent an arylene group which may have a substituent, X each independently represents a single bond or a divalent linking group, and the formula (II ), Ar ³ and Ar ⁴ each independently represent an optionally substituted arylene group, Y represents each independently a single bond or a divalent linking group, and k represents an integer of 0 or more. Represents. It is preferable to use one having a repeating structure. In addition, polyarylate resin may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

<A. Structure>
In the above formula (I) and formula (II), Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent. An arylene group is optional as long as the effects of the present invention are not significantly impaired. As carbon number which an arylene group has, it is 6 or more normally, and the upper limit is 20 or less normally, Preferably it is 10 or less. When there are too many carbon numbers, an electrical property may deteriorate.

Specific examples of the arylene group 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.

Ar ^{1 to} Ar ⁴ may each independently have a substituent. Specific examples of the substituent 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.
In Ar ¹ and Ar ² , the number of substituents is preferably 0 or more and 2 or less, and more preferably has a substituent from the viewpoints of adhesiveness and cleaning properties. Among these, from the viewpoint of abrasion resistance It is particularly preferable that the number of substituents is one. Moreover, as a substituent, an alkyl group is preferable and a methyl group is particularly preferable.

From the above viewpoint, it is preferable that at least one of Ar ¹ and Ar ² is an arylene group having a substituent.
On the other hand, Ar ³ and Ar ⁴ 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 (1), X and Y each independently represent a single bond or a divalent linking group. Preferable examples of X and Y include a sulfur atom, an oxygen atom, a sulfonyl group, a cycloalkylidene group such as cyclopentylidene and cyclohexylidene, and —CR ^a R ^b —.

Here, R ^a and R ^b each independently represent a hydrogen atom, an alkyl group, an aryl group, a halogen group, or an alkoxy group. Further, among R ^a and R ^b , considering the mechanical properties as the binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the alkyl group includes a methyl group, an ethyl group, a propyl group, An isopropyl group is preferred, 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 a methoxy group, ethoxy group, propoxy group or butoxy group. Is preferred.

In addition, when R ^a or R ^b is an alkyl group, the 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.
Furthermore, in consideration of the convenience in producing a divalent hydroxy compound (diol component represented by the formula (I)) that is usually used in producing a polyarylate resin, X is a sulfur atom or an oxygen atom. , Cyclohexylidene, and -CR ^a R ^b -are preferred. Among these, X is preferably —CR ^a R ^b —, and R ^a and R ^b are more preferably a hydrogen atom or an alkyl group such as a methyl group. From the viewpoint of wear resistance, R ^a and R ^b It is particularly preferable that at least one of ^b is a hydrogen atom.

  On the other hand, in consideration of the convenience in producing a divalent dicarboxy compound (dicarboxylic acid component represented by the formula (II)) usually used in producing a polyarylate resin, Y is a single bond, A divalent linking group having 3 or less atoms such as an oxygen atom, a sulfur atom, or a methylene group is preferable. From the viewpoint of wear resistance and cleaning properties, a single bond, an oxygen atom, and a divalent linking group having 3 or less atoms. A group is preferred, and an oxygen atom is particularly preferred.

In the formula (II), k is an integer of 0 or more. Among these, k is preferably 0 or 1 in view of simplicity in producing a polyarylate resin, and k is particularly preferably 1 from the viewpoint of wear resistance. That is, in the above formula (II), it is preferable that Y is an oxygen atom and k = 1.
What is preferable as a repeating structure which polyarylate resin has is described below. However, the repeating structure that the polyarylate resin may have is not limited to the repeating structure described below. Moreover, 1 type of the following structure may be included independently and 2 or more types may be included in arbitrary ratios and combinations.
・ Repeated structure when k is 0

・ Repeated structure when k is 1

  The amount of the repeating structure comprising the formulas (I) and (II) contained in the polyarylate resin is arbitrary as long as the effects of the present invention are not significantly impaired. However, the larger the mass ratio of the repetitive structure portion, the better from the viewpoint of electrical characteristics and wear resistance. Specifically, with respect to the polyarylate resin, the repeating structure composed of the formulas (I) and (II) is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. It is particularly preferable that all of the repeating structures of the polyarylate resin are structures composed of the formulas (I) and (II).

  Moreover, as a specific example of the dicarboxylic acid component represented by the formula (II) that forms the polyarylate resin, it is preferable to use a dicarboxylic acid component having the following structure.

  Among the above-mentioned ones, a dicarboxylic acid component having the following structure is preferable from the viewpoints of electrical characteristics and wear resistance.

On the other hand, examples of the diol component represented by the formula (I) that forms the polyarylate resin include bisphenol compounds and biphenol compounds. A diol component may also be used individually by 1 type and may use 2 or more types by arbitrary ratios and combinations.
Specific examples thereof include 4,4′-biphenol, 3,3′-dimethyl-4,4′-dihydroxy-1,1′-biphenyl, 3,3′-di (t-butyl) -4,4 ′. -Dihydroxy-1,1'-biphenyl, 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxy-1,1'-biphenyl, 3,3', 5,5'-tetra (t -Butyl) -4,4'-dihydroxy-1,1'-biphenyl, 2,2 ', 3,3', 5,5'-hexamethyl-4,4'-dihydroxy-1,1'-biphenyl, 2, , 4′-biphenol, 3,3′-dimethyl-2,4′-dihydroxy-1,1′-biphenyl, 3,3′-di (t-butyl) -2,4′-dihydroxy-1,1 ′ -Biphenyl, 2,2'-biphenol, 3,3'-dimethyl-2,2'-dihydroxy-1,1'-biphenyl, 3,3'-di biphenol compounds such as t-butyl) -2,2'-dihydroxy-1,1'-biphenyl; bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) butane, 1,1 -Bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) pentane, 3,3-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) -3- Methylbutane, 1,1-bis (4-hydroxyphenyl) hexane, 2,2-bis (4-hydroxyphenyl) hexane, 3,3-bis (4 Hydroxyphenyl) hexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, etc. A bisphenol compound having no substituent on the aromatic ring;
Bis (3-phenyl-4-hydroxyphenyl) methane, 1,1-bis (3-phenyl-4-hydroxyphenyl) ethane, 1,1-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2 A bisphenol compound having an aryl group as a substituent on an aromatic ring such as bis (3-phenyl-4-hydroxyphenyl) propane; bis (4-hydroxy-3-methylphenyl) methane, 1,1-bis (4 -Hydroxy-3-methylphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis ( 4-hydroxy-3-methylphenyl) cyclohexane, bis (4-hydroxy-3-ethylphenyl) methane, 1,1-bis (4 Hydroxy-3-ethylphenyl) ethane, 1,1-bis (4-hydroxy-3-ethylphenyl) propane, 2,2-bis (4-hydroxy-3-ethylphenyl) propane, 1,1-bis (4 -Hydroxy-3-ethylphenyl) cyclohexane, 2,2-bis (4-hydroxy-3-isopropylphenyl) propane, 2,2-bis (4-hydroxy-3- (sec-butyl) phenyl) propane, bis (4-hydroxy-3,5-dimethylphenyl) methane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) ethane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) Propane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) cyclohexane, bis (4-hydroxy-3,6-dimethylphenyl) Nyl) methane, 1,1-bis (4-hydroxy-3,6-dimethylphenyl) ethane, 2,2-bis (4-hydroxy-3,6-dimethylphenyl) propane, bis (4-hydroxy-2, 3,5-trimethylphenyl) methane, 1,1-bis (4-hydroxy-2,3,5-trimethylphenyl) ethane, 2,2-bis (4-hydroxy-2,3,5-trimethylphenyl) propane Bis (4-hydroxy-2,3,5-trimethylphenyl) phenylmethane, 1,1-bis (4-hydroxy-2,3,5-trimethylphenyl) phenylethane, 1,1-bis (4-hydroxy) Bisphenol compounds having an alkyl group as a substituent on an aromatic ring such as -2,3,5-trimethylphenyl) cyclohexane; L) (phenyl) methane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -1-phenylpropane, bis (4-hydroxyphenyl) (diphenyl) ) Bisphenol compounds in which a divalent group connecting aromatic rings such as methane and bis (4-hydroxyphenyl) (dibenzyl) methane has an aryl group as a substituent.

  Among the above, the diol component preferably has the following structure.

<B. Physical properties>
The viscosity average molecular weight of the polyarylate resin is arbitrary as long as the effects of the present invention are not significantly impaired. It is desirable that If the value of the viscosity average molecular weight is too small, the mechanical strength of the polyarylate 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 There is. 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.

  The amount of the carboxyl group present at the terminal of the polyarylate resin is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 30 μeq / g or less, preferably 15 μeq / g or less, more preferably with respect to the polyarylate resin. Is 10 μeq / g or less, particularly preferably 5 μeq / g or less. If the amount of terminal carboxyl groups is too large, electrical characteristics such as an increase in surface potential may be deteriorated. In addition, the smaller the amount of terminal carboxyl groups, the more the charge transport material can be prevented from decomposing.

The amount of terminal carboxyl groups can be quantified by, for example, dissolving a precisely weighed polyarylate resin in benzyl alcohol and titrating with 0.01 N sodium hydroxide-benzyl alcohol solution.
The amount of nitrogen contained in the molecular chain of the polyarylate resin is usually 100 ppm or less, preferably 50 ppm or less, more preferably 20 ppm or less with respect to the polyarylate resin. When the amount of nitrogen is too large, electrical characteristics such as an increase in surface potential may be deteriorated. The amount of nitrogen in the polyarylate resin can be measured by, for example, a total nitrogen analyzer (TN-10) manufactured by Mitsubishi Chemical Corporation.

The amount of acid chloride groups (—COCl) remaining at the terminal of the polyarylate resin is usually 1 μeq / g or less, preferably 0.3 μeq / g or less, particularly preferably 0.1 μeq / g, relative to the polyarylate resin. It is as follows. When the amount of acid chloride groups is too large, the storage stability may be lowered.
The amount of the terminal acid chloride group is determined by, for example, dissolving a precisely weighed polyarylate resin in methylene chloride, adding a 1% by mass methylene chloride solution of 4- (p-nitrobenzyl) pyridine, and developing the absorbance at a wavelength of 440 nm. taking measurement. Then, the amount of acid chloride groups in the polyarylate resin can be quantified by separately obtaining an extinction coefficient using a methylene chloride solution of benzoyl chloride.

  Furthermore, the amount of hydroxyl groups present at the terminal of the polyarylate resin is arbitrary as long as the effects of the present invention are not significantly impaired, but is preferably 50 μeq / g or less, more preferably 20 μeq / g or less. When the amount of hydroxyl groups is too large, electrical characteristics such as an increase in surface potential may be deteriorated. The amount of terminal hydroxyl groups can be quantified by, for example, coloring with titanium tetrachloride by acidification with acetic acid and measuring the absorbance at a wavelength of 480 nm.

[1-3-3. Polycarbonate resin]
As the polycarbonate resin, a polycarbonate resin having a repeating structure represented by the following formula (III) is preferably used.

(In formula (III), Ar ⁵ and Ar ⁶ each independently represent an arylene group which may have a substituent, and X ² represents a single bond or a divalent linking group.)
In the above formula (III), Ar ⁵ and Ar ⁶ each independently represent an arylene group which may have a substituent. Examples of the arylene group include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, naphthylene group, anthrylene group, and phenanthrylene group. From the viewpoint of electrical characteristics, 1,4-phenylene group is exemplified. Groups are preferred.

Ar ⁵ and Ar ⁶ may each independently have a substituent. Specific examples of the substituent include an alkyl group, an aryl group, a halogen group, and an alkoxy group. Among these, considering the mechanical properties as the 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. The group is preferably a phenyl group or a naphthyl group, the halogen group is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and the alkoxy group is preferably exemplified by a methoxy group, an ethoxy group, a propoxy group and 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.
Ar ⁵ and Ar ⁶ each independently have no substituent or preferably have one or two substituents, and have one or two substituents from the viewpoint of adhesiveness. Is more preferable, and it is particularly preferable to have one substituent from the viewpoint of slipperiness. As the substituent, an alkyl group is preferable, and a methyl group is particularly preferable.

In the formula (III), X ² represents a single bond or a divalent linking group. Specific examples of suitable X ² include a sulfur atom, an oxygen atom, a sulfonyl group, a carbonyl group, a cycloalkylidene group such as cyclopentylidene and cyclohexylidene, and —CR ^c R ^d —.
Here, R ^c and R ^d each independently represent a hydrogen atom, an alkyl group, an aryl group, a halogen group, or an alkoxy group. In addition, among R ^c and R ^d , if considering the mechanical properties as the binder resin for the charge transport layer and the solubility in the coating solution for forming the charge transport layer, the alkyl group may be methyl, ethyl, propyl. Group, isopropyl group is preferable, aryl group is preferably phenyl group, naphthyl group, halogen group is preferably fluorine atom, chlorine atom, bromine atom, iodine atom, alkoxy group is methoxy group, ethoxy group, propoxy group, A butoxy group is preferred.

In addition, when ^Rc or ^Rd is an alkyl group, the carbon number of the alkyl group is usually 1 or more, usually 10 or less, preferably 8 or less, more preferably 2 or less.
Furthermore, considering the convenience in producing a divalent hydroxy compound that is usually used in producing a polycarbonate resin, X ² may be a sulfur atom, an oxygen atom, cyclohexylidene, or —CR ^c R ^d —. preferable. Among these, X ² is preferably —CR ^c R ^d —, R ^c and R ^d are more preferably a hydrogen atom or an alkyl group such as a methyl group, and from the viewpoint of wear resistance, R ^c and It is particularly preferable that at least one of R ^d is a hydrogen atom.
Among these, polycarbonate resins formed from bisphenol or biphenol shown below are preferably used.

The polycarbonate resin may contain a polycarbonate structure other than that represented by the above formula (III) as a partial structure. Further, the partial structure may include a structure other than the polycarbonate resin.
In the above polycarbonate resin, the mass ratio of the partial structure represented by the formula (III) is preferably as large as possible from the viewpoints of electrical characteristics and wear resistance. Specifically, the partial structure represented by the formula (III) is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more with respect to the total mass of the polycarbonate resin. In particular, the content is desirably 100% by mass.

[1-3-4. Charge transport material]
As the charge transport material, known materials can be used, but in the present invention, the energy level E_homo of HOMO by the structure optimization calculation using the charge transport material B3LYP / 6-31G (d, p) is E_homo> −4.68 (eV), E_homo> −4.63 (eV) is more preferable, and E_homo> −4.50 (eV) is most preferable. This is because the higher the HOMO energy level, the lower the post-exposure potential and the better the electrophotographic photoreceptor. On the other hand, if E_homo is too high, problems such as a decrease in gas resistance and the occurrence of ghosts occur. (eV) is more preferable.

In addition, HF / 6-3 in the stable structure obtained after structural optimization calculation using B3LYP / 6-31G (d, p)
The calculated value αcal of the polarizability α by 1G (d, p) calculation is αcal> 80 (Å ³ ), more preferably αcal> 90 (Å ³ ), and αcal> 110 (Å ³ ) It is particularly preferred. This is because a charge transport film containing a charge transport material having a large αcal exhibits high charge mobility, and by using the charge transport film, an electrophotographic photoreceptor excellent in chargeability and sensitivity can be obtained. On the other hand, if αcal is too large, the solubility of the charge transport material decreases, and therefore, αcal <200 (Å ³ ), and preferably αcal <150 (Å ³ ), and αcal <130 (Å ³ ) It is more preferable that

Charge transport materials that satisfy both E_homo> -4.68 (eV) and αcal> 80 (Å ³ ) combine the advantages of the two parameters as described above, and have low post-exposure potential and excellent response. Therefore, it can be used even in a low number of copies, and therefore it is difficult to impair the properties of the binder. Therefore, the adhesive property inherent to the binder becomes an issue, and as described later, by setting the blending ratio of the charge generation material and the binder to a specific range, the electrophotographic photoreceptor can be used even when the charge transport material is included. Does not impair functionality.

In the present invention, the energy level E_homo of HOMO is a type of density functional B3LYP (AD Becke, J. Chem. Phys. 98, 5648 (1993), C. Lee, W. Yang, and RG Parr, Phys. Rev. B37, 785 (1988) and B. Miehlich, A. Savin, H. Stoll, and H. Preuss, Chem. Phys. Lett. 157, 200 (1989)). I got it. At this time, 6-31G (d, p) obtained by adding a polarization function to 6-31G was used as the basis set (R. Ditchfield, WJ Hehre, and JA Pople, J. Chem. Phys. 54, 724 (1971 ), WJ Hehre, R. Ditchfield, and JA Pople, J. Chem. Phys. 56, 2257 (1972), PC Hariharan and JA
Pople, Mol. Phys. 27, 209 (1974), MS Gordon, Chem. Phys. Lett. 76, 163 (1980),
PC Hariharan and JA Pople, Theo. Chim. Acta 28, 213 (1973), J.-P. Blaudeau, MP McGrath, LA Curtiss, and L. Radom, J. Chem. Phys. 107, 5016 (1997), MM Francl, WJ Pietro, WJ Hehre, JS Binkley, DJ DeFrees, JA Pople, and MS Gordon, J. Chem. Phys. 77, 3654 (1982), RC Binning Jr. and LA Curtiss, J. Comp. Chem. 11, 1206 (1990), VA Rassolov, JA Pople, MA Ratner, and TL Windus, J. Chem. Phys. 109, 1223 (1998), and VA Rassolov, MA Ratner, JA Pople, PC Redfern, and LA Curtiss, J. Comp. Chem. 22, 976 (2001)). In the present invention, B3LYP calculation using 6-31G (d, p) is described as B3LYP / 6-31G (d, p).

Furthermore, the polarizability αcal is calculated by the restricted Hartree-Fock method (“Modern Quantum Chemistry”, A. Szabo and NS Ostlund, McGraw) in the stable structure obtained by the structure optimization calculation by B3LYP / 6-31G (d, p). -See Hill publishing company, New York, 1989). At this time, 6-31G (d, p) was used as the basis function. In the present invention, the Hartree-Fock calculation using 6-31G (d, p) is described as HF / 6-31G (d, p).

In the present invention, the program used for B3LYP / 6-31G (d, p) calculation and HF / 6-31G (d, p) calculation is Gaussian 03, Revision D. 01 (MJ Frisch, GW Trucks, HB Schlegel, GE Scuseria, MA Robb, JR Cheeseman, JA Montgomery, Jr., T. Vreven, KN Kudin,
JC Burant, JM Millam, SS lyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, GA Petersson, H. Nakatsuji, M. Hada, M. Ehara,
K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, JE Knox, HP Ilratchian, JB Cross, V . Bakken,
C. Adamo, J. Jaramillo, R. Gomperts, RE Stratmann, O. Yazyev, AJ Austin, R. Cammi, C. Pomelli, JW Ochterski, PY Ayala, K. Morokuma, GA Voth, P. Salvador, JJ Dannenberg, VG Zakrzewski, S. Dapprich, AD Daniels, MC Strain, O. Farkas, DK Malick, AD Rabuck, K. Raghavachari, JB Foresman,
JV Ortiz, Q. Cui, AG Baboul, S. Clifford, J. Cioslowski, BB Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, RL Martin, DJ Fox, T. Keith,
(Ma Al-Laham, CY Peng, A. Nanayakkara, M. Challacombe, PMW Gill, B. Johnson, W. Chen, MW Wong, C. Gonzalez, and JA Pople, Gaussian, Inc., Wallingford CT, 2004.) is there.
For example, typical charge transport materials have values shown in Table 1.

  The molecular weight of the charge transport material is usually 600 or more, preferably 650 or more from the viewpoint of charge transport ability, and usually 2000 or less, preferably 1200 or less from the viewpoint of solubility. Specifically, the following compounds (1) to (3) are preferably used. A compound such as (1) or (3) is particularly preferred.

In formula (1), R ^{1 to} R ⁵ each represents an independent hydrogen atom, alkyl group, aryl group, or alkoxy group. n represents an integer of 1 to 3, k, l, o, and p each independently represent an integer of 1 to 5, and m each independently represents an integer of 1 to 4. Z represents a phenylene group which may have an alkyl group, an aryl group or an alkoxy group, or a single bond. A represents a phenyl group which may have a hydrogen atom or an alkyl group.

In the above formula (1), R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group. Specifically, examples of the alkyl group include a methyl group, an ethyl group, and n- Examples thereof include linear alkyl groups such as propyl group and n-butyl group, branched alkyl groups such as isopropyl group and ethylhexyl group, and cyclic alkyl groups such as cyclohexyl group. The aryl group has a substituent. Phenyl group, naphthyl group and the like may be mentioned, and as alkoxy group, straight chain alkoxy group such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, isopropoxy group, ethylhexyloxy group, etc. A branched alkyl group, and a cyclohexyloxy group. Among these, a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group are preferable from the viewpoints of versatility of production raw materials and charge transport ability as a charge transport material. The bonding position of each substituent with respect to the benzene ring can be usually any of the o-position, m-position and p-position with respect to the vinyl group, but from the viewpoint of ease of production, the o-position or p-position. Any of the positions is preferred.

In the above formula (1), R ^{3 to} R ⁵ each independently represents a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group. Specifically, examples of the alkyl group include a methyl group, an ethyl group, and n -Linear alkyl groups such as propyl group and n-butyl group, branched alkyl groups such as isopropyl group and ethylhexyl group, and cyclic alkyl groups such as cyclohexyl group. The aryl group has a substituent. Phenyl group, naphthyl group, etc., which may be included, and as alkoxy group, linear alkoxy group such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, isopropoxy group, ethylhexyloxy group And branched alkyl groups such as cyclohexyloxy and the like. Among these, a hydrogen atom, a C1-C8 alkyl group, and a C1-C8 alkoxy group are preferable from the versatility of a manufacturing raw material, and a hydrogen atom and a C1-C6 from the surface of the handleability at the time of manufacture are preferable. More preferred are alkyl groups having 1 to 6 carbon atoms, and more preferred are hydrogen atoms and alkyl groups having 1 to 2 carbon atoms from the viewpoint of light attenuation characteristics as an electrophotographic photoreceptor, and charge as a charge transport material. From the viewpoint of transport ability, a hydrogen atom is particularly preferable.

In the above formula (1), Z represents an alkyl group, an aryl group, a phenylene group which may have an alkoxy group or a single bond. Specifically, examples of the alkyl group include a methyl group, an ethyl group, n -Linear alkyl groups such as propyl group and n-butyl group, branched alkyl groups such as isopropyl group and ethylhexyl group, and cyclic alkyl groups such as cyclohexyl group. The aryl group has a substituent. Phenyl group, naphthyl group, etc., which may be present, include alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, straight chain alkoxy group, isopropoxy group, ethylhexyloxy group, etc. And branched alkyl groups such as cyclohexyloxy and the like. Among these, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable from the viewpoint of versatility of production raw materials, and a hydrogen atom and carbon number of 1 from the viewpoint of handling at the time of manufacture. More preferable are an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms. From the viewpoint of light attenuation characteristics as an electrophotographic photoreceptor, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms are preferable. More preferably, an alkyl group having 1 to 4 carbon atoms is particularly preferable from the viewpoint of resistance to ozone of the electrophotographic photoreceptor, and a methyl group and an ethyl group are most preferable from the viewpoint of charge transport ability as a charge transport material. Furthermore, when R ^{6 to} R ⁷ are a methyl group or an ethyl group, the bonding position of each substituent to the benzene ring can be any position of the o-position, m-position or p-position with respect to the styryl group. However, from the viewpoint of ease of production, either the o-position or the p-position is preferable. When the total of alkyl groups such as methyl group and ethyl group for one benzene ring is 2 or more, it is preferably substituted at either o-position or p-position, from the viewpoint of electrophotographic photoreceptor characteristics, More preferably, the total number of alkyl groups is 2, and it is more preferable that the two substituents are respectively substituted at the p-position and the o-position, or both are substituted at the o-position.

In the above formula (1), examples of the alkyl group in the case where A is a phenyl group optionally having an alkyl group include those described above.
k, l, o, and p are each independently an integer of 1 to 5, and m is independently an integer of 1 to 4. k, l, m, o, when p represents an integer of 2 or more, may be different plurality of R ¹ to R ⁴ bonded to the benzene ring, respectively, also, a plurality of R ¹ ~ bonded to the benzene ring R ⁴ may also be different from each other.

n represents an integer of 1 to 3. When n increases, the solubility in the coating solvent tends to decrease, preferably 1 or 2, and more preferably 2 from the viewpoint of charge transport ability as a charge transport material.
The arylene group portion to which the diphenylamino group is bonded represents a phenylene group when n = 1, a biphenylene group when n = 2, or a terphenylene group when n = 3. The position at which the two diphenylamino groups are bonded to the arylene group is not limited as long as the effect of the present invention is not significantly impaired. However, when n = 1, the two diphenylamino groups have two diphenylamino groups from the viewpoint of the chargeability of the electrophotographic photosensitive member. It is preferable that the m-position relationship is established at the bonding position of the phenylene group. In the case of n = 2, from the viewpoint of charge transport ability as a charge transport material, the position where the diphenylamino group is bonded to the biphenylene group is preferably bonded to the 4th and 4 ′ positions of the biphenylene group, and n = 3 In this case, a p-terphenylene group is preferable among the terphenylene groups because of the versatility of the raw materials for production, and the bonding position of the diphenylamine group to the p-terphenylene group is 4-position and 4- Bonding at the '' position is preferred.

In addition, the electrophotographic photoreceptor of the present invention may usually contain a compound represented by the formula (1) as a single component in the photosensitive layer, or compounds having different structures represented by the formula (1). You may contain as a mixture of these. As a mixture, in the case where a plurality of so-called positional isomers, in which only the substitution positions of R ^{1 to} R ⁵ are different, are mixed in the structure represented by the formula (1), the mutual electronic state is close and the charge transport trap In addition to being difficult to become, it is preferable from the viewpoint of suppressing crystal formation in the coating solution or film. As the positional isomers, it is more preferable to use a mixture of R ¹ and R ² having different substitution positions from the viewpoint of ease of synthesis of the compound, and the substitution positions of R ¹ and R ² are in the o position. , P-position is most preferably used in combination.
Moreover, in said formula (2), R < ⁸ > -R < ¹² > represents an independent hydrogen atom, an alkyl group, an aryl group, and an alkoxy group, respectively. s, t, and u represent integers of 1 to 5, and v and w represent integers of 1 to 4, respectively.

In the formula (2), R ⁸ represents any one of a hydrogen atom, an alkyl group, an aryl group, and an alkoxy group. Specifically, examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an n- Examples include linear alkyl groups such as butyl groups, branched alkyl groups such as isopropyl groups and ethylhexyl groups, and cyclic alkyl groups such as cyclohexyl groups, and aryl groups include phenyl groups that may have a substituent. , A naphthyl group, etc., and the alkoxy group includes a linear alkyl group such as a methoxy group, an ethoxy group, an n-propoxy group and an n-butoxy group, a branched alkyl group such as an isopropoxy group and an ethylhexyloxy group. And a cyclohexyloxy group. Among these, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable from the viewpoint of versatility of the production raw material. More preferable are an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms. From the viewpoint of light attenuation characteristics as an electrophotographic photoreceptor, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms are preferable. Further, an alkyl group having 1 to 4 carbon atoms is particularly preferable from the viewpoint of resistance to ozone of the electrophotographic photosensitive member, and a linear or branched alkyl group having 3 to 4 carbon atoms is most preferable from the viewpoint of solubility. Further, when R ⁸ is an alkyl group, the substituent can be bonded to the benzene ring at any position of the o-position, m-position or p-position with respect to the styryl group. In view of the above, the o-position and / or the p-position are preferable.

In the above formula (2), R ⁹ and R ¹⁰ each independently represents a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group. Specifically, examples of the alkyl group include a methyl group, an ethyl group, and n -Linear alkyl groups such as propyl group and n-butyl group, branched alkyl groups such as isopropyl group and ethylhexyl group, and cyclic alkyl groups such as cyclohexyl group. The aryl group has a substituent. Phenyl group, naphthyl group, etc., which may be included, and as alkoxy group, linear alkoxy group such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, isopropoxy group, ethylhexyloxy group And branched alkyl groups such as cyclohexyloxy and the like. Among these, a hydrogen atom, a C1-C8 alkyl group, and a C1-C8 alkoxy group are preferable from the versatility of a manufacturing raw material, and a hydrogen atom and a C1-C6 from the surface of the handleability at the time of manufacture are preferable. More preferred are alkyl groups having 1 to 6 carbon atoms, and more preferred are hydrogen atoms and alkyl groups having 1 to 2 carbon atoms from the viewpoint of light attenuation characteristics as an electrophotographic photoreceptor, and charge as a charge transport material. From the viewpoint of transport ability, a hydrogen atom is particularly preferable.

In the above formula (2), R ¹¹ and R ¹² are each independently a hydrogen atom, an alkyl group,
Represents an aryl group or an alkoxy group. Specifically, the alkyl group may be a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group or an n-butyl group, a branched group such as an isopropyl group or an ethylhexyl group. Examples thereof include cyclic alkyl groups such as an alkyl group and a cyclohexyl group. Examples of the aryl group include a phenyl group and a naphthyl group which may have a substituent. Examples of the alkoxy group include a methoxy group, an ethoxy group, Examples include linear alkoxy groups such as n-propoxy group and n-butoxy group, branched alkyl groups such as isopropoxy group and ethylhexyloxy group, and cyclohexyloxy group. Among these, a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group are preferable from the viewpoints of versatility of production raw materials and charge transport ability as a charge transport material. The bonding position of each substituent to the benzene ring can be usually any of the o-position, m-position and p-position with respect to the styryl group, but from the viewpoint of ease of production, the o-position or p-position. Any of the positions is preferred.

In the above formula (3), Ar ^{5 to} Ar ⁹ each represents an aryl group which may have an independent substituent, and Ar ^{10 to} Ar ¹³ each represent an arylene group which may have an independent substituent. Represents. a and b each independently represent an integer of 1 to 3. In the above formula (1), Ar ^{5 to} Ar ⁹ each independently represents an aryl group which may have a substituent. The number of carbon atoms of the aryl group is 30 or less, preferably 20 or less, more preferably 15 or less. Specific examples include a phenyl group, a naphthyl group, a biphenyl group, an anthryl group, and a phenanthryl group. Among these, in consideration of the characteristics of the electrophotographic photosensitive member, a phenyl group, a naphthyl group, and an anthryl group are preferable. From the viewpoint of charge transport capability, a phenyl group and a naphthyl group are more preferable, and a phenyl group is further preferable. Examples of the substituent that Ar ^{5 to} Ar ⁹ may have include an alkyl group, an aryl group, an alkoxy group, and a halogen atom. Specifically, examples of the alkyl group include a methyl group, an ethyl group, and n-propyl. Groups, linear alkyl groups such as n-butyl group, branched alkyl groups such as isopropyl group and ethylhexyl group, and cyclic alkyl groups such as cyclohexyl group. The aryl group may have a substituent. Examples thereof include a phenyl group and a naphthyl group, and examples of the alkoxy group include linear alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group, an isopropoxy group, and an ethylhexyloxy group. Cyclic alkoxy groups, cyclic alkoxy groups such as cyclohexyloxy group, trifluoromethoxy group, pentafluoroethoxy group, 1,1,1-trifluoro They include alkoxy groups having a fluorine atom such as Oroetokishi group, the halogen atom fluorine atom, chlorine atom, bromine atom and the like. Among these, an alkyl group having 1 to 20 carbon atoms and an alkoxy group having 1 to 20 carbon atoms are preferable from the versatility of production raw materials, and an alkyl group having 1 to 12 carbon atoms and carbon number from the viewpoint of handleability during production. An alkoxy group having 1 to 12 carbon atoms is more preferable, and an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms are more preferable from the viewpoint of light attenuation characteristics as an electrophotographic photoreceptor. In the case where Ar ^{5 to} Ar ⁹ are phenyl groups, it is preferable to have a substituent from the viewpoint of charge transport ability, and the number of substituents can be 1 to 5, but from the versatility of manufacturing raw materials, 1 1 to 3 are preferable, and from the viewpoint of the characteristics of the electrophotographic photosensitive member, 1 to 2 are more preferable, and when Ar ^{1 to} Ar ⁵ are naphthyl groups, the number of substituents from the versatility of the production raw material Is preferably 2 or less or not having a substituent, and more preferably, the number of substituents is 1 or having no substituent. Ar ⁵ preferably has at least one substituent at the ortho position or the para position with respect to the nitrogen atom, and the substituent is preferably an alkoxy group having 1 to 6 carbon atoms or 1 to 12 carbon atoms from the viewpoint of solubility. Are preferred.

In the above formula (3), Ar ^{10 to} Ar ¹³ each independently represent an arylene group which may have a substituent. The number of carbon atoms of the aryl group is 30 or less, preferably 20 or less, more preferably 15 or less. Specific examples include a phenylene group, a biphenylene group, a naphthylene group, an anthrylene group, and a phenanthrylene group. Among these, a phenylene group and a naphthylene group are preferable, and a phenylene group is more preferable in consideration of the characteristics of the electrophotographic photoreceptor. is there. Examples of the substituent that Ar ^{6 to} Ar ⁹ may have include an alkyl group, an aryl group, an alkoxy group, and a halogen atom. Specifically, examples of the alkyl group include a methyl group, an ethyl group, and n-propyl. Groups, linear alkyl groups such as n-butyl group, branched alkyl groups such as isopropyl group and ethylhexyl group, and cyclic alkyl groups such as cyclohexyl group. The aryl group may have a substituent. Examples thereof include a phenyl group and a naphthyl group, and examples of the alkoxy group include linear alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group, an isopropoxy group, and an ethylhexyloxy group. Cyclic alkoxy groups, cyclic alkoxy groups such as cyclohexyloxy group, trifluoromethoxy group, pentafluoroethoxy group, 1,1,1-trifluoro They include alkoxy groups having a fluorine atom such as Oroetokishi group, the halogen atom fluorine atom, chlorine atom, bromine atom and the like. Among these, a C1-C6 alkyl group and a C1-C6 alkoxy group are preferable from the versatility of a manufacturing raw material, and a C1-C4 alkyl group and carbon number from the surface of the handling property at the time of manufacture 1-4 alkoxy groups are more preferable, and a methyl group, an ethyl group, a methoxy group, and an ethoxy group are more preferable from the viewpoint of light attenuation characteristics as an electrophotographic photosensitive member.

When Ar ^{10 to} Ar ¹³ have a substituent, the molecular structure is twisted, and π-conjugate expansion in the molecule may be hindered, and the electron transport capability may be reduced. Therefore, Ar ^{10 to} Ar ¹³ may be substituted. In view of the characteristics of the electrophotographic photosensitive member, 1,3-phenylene group, 1,4-phenylene group, 1,4-naphthylene group, 2,6-naphthylene group, 2,8-naphthylene are preferable. A group is more preferable, and a 1,4-phenylene group is more preferable.

a and b each independently represent an integer of 1 to 3. Since a solubility in a coating solvent tends to decrease as a and b increase, it is preferably 2 or less, and more preferably 1 from the viewpoint of charge transport ability as a charge transport material. When a and b are 1, it represents an ethenyl group and has a geometric isomer, but a trans structure is preferable from the viewpoint of the characteristics of an electrophotographic photoreceptor. When a and b are 2, it represents a butadienyl group, which also has a geometric isomer, but is preferably a mixture of two or more geometric isomers from the viewpoint of coating solution storage stability.
Further, the electrophotographic photoreceptor of the present invention may usually contain a compound represented by formula (3) as a single component in the photosensitive layer, or as a mixture of compounds represented by formula (3). It can also be contained.
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.

  The ratio of the binder resin and the charge transport material in the photosensitive layer is such that the charge transport material is used in a ratio of 32 parts by mass or more with respect to 100 parts by mass of all the binder resins in the same layer. Among these, 33 parts by mass or more is preferable from the viewpoint of reducing the residual potential, and 35 parts by mass or more is more preferable 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 50 parts by mass or less. Among these, 45 parts by mass or less is preferable from the viewpoint of compatibility between the charge transport material and the binder resin, and 40 parts by mass or less is more preferable from the viewpoint of scratch resistance.

The charge transport layer of the function-separated type photoconductor (that is, the multilayer photoconductor) having a charge generation layer and a charge transport layer is a coating solution obtained by dissolving or dispersing a charge transport material and various binder resins in a solvent. Can be obtained by coating and drying.
<Charge generation layer>
In the case of a multilayer type photoreceptor (function separation type photoreceptor), the charge generation layer is formed by binding a charge generation material with a binder resin.

  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, but organic photoconductive materials are preferred, especially organic pigments. Is 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 generation material, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

  When a metal-free phthalocyanine compound or a metal-containing phthalocyanine compound is used as the charge generation material, a photosensitive member having a high sensitivity to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm, is obtained. When an azo pigment such as diazo or trisazo is used, it is sufficient for white light, laser light having a wavelength around 660 nm, or laser light having a relatively short wavelength, for example, laser having a wavelength around 450 nm or 400 nm. A photosensitive member having a high sensitivity can be obtained.

When an organic pigment is used as the charge generating material, a phthalocyanine pigment or an azo pigment is particularly preferable. The phthalocyanine pigment provides a photosensitive material with high sensitivity to a laser beam having a relatively long wavelength, and the azo pigment has a sufficient sensitivity to white light and a laser beam having a relatively short wavelength. , Each is excellent.
When using a phthalocyanine pigment as a charge generation material, specifically, metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, aluminum or other metal or oxide thereof, halide, water Those having crystal forms of coordinated phthalocyanines such as oxides 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 crystalline 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 and 28.1 ° have the strongest peaks, and 26.2 ° have peaks Hydroxygallium phthalocyanine having 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. Among these, D-type (Y-type) titanyl phthalocyanine is most preferable because it shows good sensitivity.

  The phthalocyanine compound may be a single compound or several mixed or mixed crystal states. As the mixed state that can be put in the phthalocyanine compound or crystal state here, those obtained by mixing the respective constituent elements later may be used, or they may be mixed in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, and crystallization. It may be the one that caused the condition. 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.

When an azo pigment is used as the charge generation material, various bisazo pigments and trisazo pigments are preferably used.
When an organic pigment is 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 charge generation layer contains polyvinyl acetal resin such as polyvinyl butyral resin, polyvinyl formal resin, and partially acetalized polyvinyl butyral resin in which a part of butyral is modified with formal or acetal. Other binder resins are not particularly limited, but examples include polyarylate resins, polycarbonate resins, polyester resins, modified ether-based polyester resins, phenoxy resins, polyvinyl chloride resins, polyvinylidene chloride resins, and polyvinyl acetate resins. , Polystyrene resin, acrylic resin, methacrylic resin, polyacrylamide resin, polyamide resin, polyvinyl pyridine resin, cellulosic resin, polyurethane resin, epoxy resin, silicon resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, vinyl chloride-vinyl acetate Vinyl chloride-vinegar such as copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer Insulating resins such as vinyl copolymers, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, styrene-alkyd resins, silicon-alkyd resins, phenol-formaldehyde resins, poly-N-vinylcarbazole, polyvinyl And organic photoconductive polymers such as anthracene and polyvinylperylene. Any one of these binder resins may be used alone, or two or more of them may be mixed and used in any combination. However, it is preferable to use only a polyvinyl acetal resin from the viewpoint of electrical characteristics. .

Specifically, the charge generation layer is prepared by dispersing the halogen-substituted indium phthalocyanine of the present invention and other charge generation materials used in some cases in a solution obtained by dissolving the above binder resin in an organic solvent. Is applied on a conductive support (or an undercoat layer when an undercoat layer is provided).
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, ester solvents such as methyl formate, ethyl acetate, n-butyl acetate, dichloromethane, Black Halogenated hydrocarbon solvents such as form, 1,2-dichloroethane, chain or cyclic ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, acetonitrile, dimethyl Aprotic polar solvents such as sulfoxide, sulfolane, hexamethylphosphoric triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, triethylenediamine, triethylamine and other nitrogen-containing compounds, ligroin and other mineral oils, water, etc. Can be mentioned. 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) wr of the charge generation material with respect to the total binder resin is 0.4 ≦ wr ≦ 1.4. The upper limit of wr is more preferably 1.0 or less from the viewpoint of adhesiveness. If it is larger than 1.3, the adhesion between the substrate and the photosensitive layer may be lowered. Further, the lower limit is 0.5 or more, and preferably 0.7 or more from the viewpoint of charge generation efficiency.
The thickness of the charge generation layer is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less.
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.

<Other ingredients>
In addition, the photosensitive layer has, for example, an antioxidant, a plasticizer, an ultraviolet absorber, an electron withdrawing property in order to improve film forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, and the like. You may contain additives, such as a compound, a leveling agent, a visible light shading agent, and a sensitizer. An additive may be used individually by 1 type and may be used 2 or more types by arbitrary ratios and combinations.

Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of dyes and pigments include various pigment compounds and azo compounds. Examples of leveling agents include silicone oil and fluorine-based oil.
Among them, those having one or more t-butyl groups on the phenol ring in the molecule are preferable, and among them, those in which the t-butyl group is bonded to the position adjacent to the phenolic hydroxyl group (that is, in the ortho position with respect to the hydroxyl group). Those having a t-butyl group bonded thereto are more preferred. Among them, those in which two t-butyl groups are bonded at positions adjacent to the phenolic hydroxyl group (that is, those in which t-butyl groups are bonded at positions 2 and 6 to the hydroxyl group) are particularly preferable. . Specific examples thereof include 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-methylphenol, and n-octadecyl. Monophenolic antioxidants such as -3- (4'-hydroxy-3 ', 5'-di-t-butylphenyl) propionate, 2,2'-methylenebis (6-t-butyl-4-methylphenol) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, pentaerythrityltetrakis [3- (3,5-di-t- Polyphenolic antioxidants such as butyl-4-hydroxyphenyl) propionate] are preferred. By using these, an electrophotographic photoreceptor free from fogging can be easily produced even when used repeatedly.
Moreover, in order to improve acid-proof gas resistance, it is possible to use the alkylamine compound which may have a well-known substituent. For example, it is preferable to use compounds disclosed in JP-A-3-172852, JP-A-2007-52408, and the like. Among these, for example, tribenzylamine can be preferably used.

<Protective layer, etc.>
A protective layer may be provided on the outermost surface layer of the photosensitive member for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to a discharge substance generated from a charger or the like. The protective layer is formed, for example, by containing a conductive material in an appropriate binder resin, or a co-layer using a compound having a charge transporting capability such as a triphenylamine skeleton as described in JP-A-9-190004. A polymer can be used. Examples of the conductive material include aromatic amino compounds such as TPD (N, N′-diphenyl-N, N′-bis- (m-tolyl) benzidine), antimony oxide, indium oxide, tin oxide, titanium oxide, and tin oxide. -Metal oxides such as antimony oxide, aluminum oxide, and zinc oxide can be used, but are not limited thereto. In addition, these may be used individually by 1 type and may be used 2 or more types by arbitrary ratios and combinations.

  As the binder resin used for the protective layer, for example, a known resin such as polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, or siloxane resin may be used. In addition, as described in JP-A-9-190004, a copolymer of a skeleton having a charge transporting ability such as a triphenylamine skeleton and the above resin can also be used. In addition, binder resin used for a protective layer may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

The protective layer is preferably formed so that the electric resistance is usually 10 ⁹ Ω · cm or more and 10 ¹⁴ Ω · cm or less. If the electrical resistance is too small, the image may be blurred or the resolution may be reduced. If the electrical resistance is too large, the residual potential may increase and an image with much fog may be formed. In addition, the protective layer is preferably formed so as not to substantially prevent transmission of light irradiated for image exposure.
Also, for example, fluorine resin, silicone resin, polyethylene resin, polystyrene resin is used for the surface layer for the purpose of reducing frictional resistance and wear on the surface of the photoreceptor, and increasing transfer efficiency of the toner from the photoreceptor to the transfer belt and paper. Etc. may be included. Further, the surface layer may contain particles made of these resins, particles of an inorganic compound, and the like.

[1-4. Layer formation method]
Each layer constituting the photoconductor is usually applied sequentially by applying a coating solution containing the material constituting each layer on the conductive support using a known coating method, repeating the coating and drying steps for each layer. Is formed.
Solvents for dissolving the binder resin and the solvent and dispersion medium used for preparing the coating liquid include, for example, saturated aliphatic solvents such as pentane, hexane, octane and nonane, aromatic solvents such as toluene, xylene and anisole, chlorobenzene, Halogenated aromatic solvents such as dichlorobenzene and chloronaphthalene, amide solvents such as dimethylformamide and N-methyl-2-pyrrolidone, alcohol solvents such as methanol, ethanol, isopropanol, n-butanol and benzyl alcohol, glycerin, Aliphatic polyhydric alcohols such as polyethylene glycol, chain, branched and cyclic ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, 4-methoxy-4-methyl-2-pentanone, methyl formate, ethyl acetate, n-butyl acetate Ester solvents such as Halogenated hydrocarbon solvents such as methylene chloride, chloroform, 1,2-dichloroethane, diethyl ether, dimethoxyethane, tetrahydrofuran (hereinafter referred to as “THF” as appropriate), 1,4-dioxane, methyl cellosolve, ethyl cell Chain and cyclic ether solvents such as sorb, aprotic polar solvents such as acetonitrile, dimethyl sulfoxide, sulfolane, hexamethylphosphoric triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, triethylenediamine, triethylamine Nitrogen-containing compounds such as ligroin, mineral oil such as ligroin, water and the like, and those that do not dissolve the above-described undercoat layer are preferably used. In addition, these may be used individually by 1 type and may be used 2 or more types by arbitrary ratios and combinations.

In the case of a charge transport layer, the coating liquid for layer formation has a solid content concentration of usually 5% by mass or more, preferably 10% by mass or more, and the upper limit is usually 40% by mass or less, preferably 35% by mass. % Or less.
Further, the viscosity of the coating solution is usually 10 mPa · s or more, preferably 50 mPa · s or more, and the upper limit thereof is usually 500 mPa · s or less, preferably 400 mPa · s or less.

In the case of a charge generating layer of a multilayer photoreceptor, the solid content concentration is usually 0.1% by mass or more, preferably 1% by mass or more, and the upper limit is usually 15% by mass or less, preferably 10% by mass. It is as follows.
The viscosity of the coating solution is usually 0.01 mPa · s or more, preferably 0.1 mPa · s or more, and the upper limit is usually 20 mPa · s or less, preferably 10 mPa · s or less.

Examples of the coating method for the coating liquid include dip coating, spray coating, spinner coating, bead coating, wire bar coating, blade coating, roller coating, air knife coating, and curtain coating. However, other known coating methods can be used. In addition, these methods may be used individually by 1 type, and may be used in combination of 2 or more types arbitrarily.
Drying after applying the coating solution is performed by touching at room temperature (usually 25 ° C), and usually in the temperature range of 30 ° C to 200 ° C, usually for 1 minute to 2 hours, with no air or air. It is preferable to dry. The heating temperature may be constant or may be changed while drying.

  In the electrophotographic photoreceptor of the present invention, in the case of a multilayer photoreceptor, the drying temperature is not particularly limited in the drying step after application of the coating solution for the charge transport layer, but the adhesion of the charge transport layer is improved. From the viewpoint, the glass transition temperature of the charge transport layer is preferably higher than the glass transition temperature, more preferably the glass transition temperature of the charge transport layer is + 10 ° C. or higher, more preferably + 20 ° C. or higher, and particularly preferably + 30 ° C. On the other hand, the glass transition temperature + 100 ° C. or lower is preferable. The lower limit of the drying temperature in the drying step after the application of the charge transport layer coating solution is usually 50 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and still more preferably. It is 120 ° C. or higher, and particularly preferably 130 ° C. or higher. On the other hand, the upper limit is usually 200 ° C. or lower, and is preferably 180 ° C. or lower from the viewpoint of productivity.

The glass transition temperature of the charge transport layer can be obtained by measuring the charge transport layer obtained through a drying step after applying the charge transport layer coating solution by a known glass transition temperature measurement method.
In addition, the thickness of the charge transport layer of the normal laminate type photoreceptor is usually in the range of 5 μm to 50 μm, but from the viewpoint of long life and image stability, it is preferably from 10 μm to 45 μm, and high resolution viewpoint. Is more preferably 10 μm or more and 30 μm or less.

<Outer diameter of electrophotographic photoreceptor>
When a drum-shaped conductive support is used, the outer diameter of the electrophotographic photosensitive member is usually 100 mm or less, preferably 80 mm or less, more preferably 30 mm or less, and still more preferably 20 mm or less. Particularly preferably, it is 16 mm or less. On the other hand, the outer diameter is usually 10 mm or more.

<2. Image forming apparatus and electrophotographic cartridge>
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 100 includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, a developing device 4, and a transfer device 5, and further, a cleaning device 6 as necessary. And a fixing device 7 is provided.
Each device will be described below.
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. Examples of the charging device include a corona charging device such as a corotron and a scorotron, a direct charging device (contact type charging device) that charges a direct charging member to which a voltage is applied by contacting the photosensitive member surface, and a contact charging device such as a charging brush Often used. Examples of direct charging means include contact chargers such as charging rollers and charging brushes. 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. In addition, as a voltage applied at the time of charging, in the case of only a direct current voltage, an alternating current can be superimposed on a direct current.

The type of 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, or monochromatic light with a wavelength of 380 nm to 500 nm. Good. Among these, it is preferable to use light having a short wavelength of 380 to 500 nm because the resolution becomes high. Among these, 405 nm monochromatic light is preferable. Moreover, the writing resolution is mainly 600 dpi or more at present, but there is a high-performance model having 1200 dpi. The resolution of the electrostatic latent image and the toner image is determined depending on the writing resolution, and the higher the resolution, the clearer the image is obtained. Therefore, a resolution of 1200 dpi or higher is preferable. For example, when writing is performed with an LED having a resolution of 600 dpi and 1200 dpi, the minimum dot formation interval is 42 μm and 21 μm, respectively.

  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 is configured to store toner T 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. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge. In the present embodiment, the toner of the present invention described above is preferably used as the toner T.

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 silicone 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 photosensitive member 1 and the supply roller 43 and is in contact with the electrophotographic photosensitive member 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 silicone 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 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 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. This transfer device 5 uses toner T
The toner image formed on the electrophotographic photosensitive member 1 is transferred onto a recording paper (paper, medium) P by applying a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of.

  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 scrapes the residual toner adhering to the electrophotographic photosensitive member 1 with a cleaning member and collects the residual toner. If there is little or almost no toner remaining on the surface of the photoreceptor, the cleaning device 6 may be omitted.

  Among these, the blade cleaning method is preferable because of its simple structure, small size, low cost, and excellent cleaning performance and reliability. In the blade cleaning method, it is possible to classify by a contact method and a pressurization method (57th Annual Meeting of the Imaging Society of Japan, P196-211). The contact method is classified into counter contact and forward contact, and the pressurization method is classified into a low displacement method and a low load method.

In the present invention, a blade cleaning method is preferable for effectively removing the toner. In particular, when a toner having a high degree of circularity is used, the counter contact method is preferable because the toner easily slips between the blade and the photoreceptor. . The linear pressure of the blade against the photosensitive member is preferably set to 20-60 g / cm.
If the blade is set under the above conditions, there is a tendency that a rubbing sound is generated between the photosensitive member and the blade, but this can be avoided by using the photosensitive member of the present invention.

  Further, when an electrophotographic photosensitive member having an outer diameter of 20 mm or less is used, since the linear pressure of the cleaning blade may be set to be particularly strong, it contacts with the electrophotographic photosensitive member of the cleaning blade in order to avoid blade reversal. It is preferable to apply a lubricant to the part. Examples of the lubricant include toner, polytetrafluoroethylene, polypropylene, and silicone resin.

  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 include 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, a fixing sheet, or the like. A fixing member can be used. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicone 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 any type such as heat roller fixing, flash fixing, oven fixing, pressure fixing, etc. can be provided including those used here.

In the electrophotographic apparatus 100 configured as described above, for example, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the electrophotographic photosensitive member 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed with a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.
Subsequently, the photosensitive surface of the charged electrophotographic photosensitive member 1 is exposed to the exposure device 3 according to the image to be recorded.
To form an electrostatic latent image on the photosensitive surface. Then, development of the electrostatic latent image formed on the photosensitive surface of the electrophotographic photoreceptor 1 is performed by the developing device 4.

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 is carried while being carried on the developing roller 44 and brought into contact with the surface of the electrophotographic photosensitive member 1.
When the charged toner T carried on the developing roller 44 contacts the surface of the electrophotographic photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the electrophotographic 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 electrophotographic photosensitive member 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 100 may have a configuration capable of performing a static elimination process, for example. 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 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 deteriorate, this electrophotographic cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic cartridge is mounted on the main body of the image forming apparatus. Maintenance and management of the forming apparatus becomes easy.

[ Reference Example 1]
A machined aluminum cylinder having an outer diameter of 30 mm, a length of 246 mm, and a thickness of 1 mm was degreased and washed at 60 ° C. for 5 minutes in a 30 g / L aqueous solution of a degreasing agent NG- # 30 (manufactured by Kizai Co., Ltd.). Subsequently, it was washed with water and then immersed in 7% nitric acid at 25 ° C. for 1 minute.
Further, after washing with water, 1.2% in 180 g / L sulfuric acid electrolyte (dissolved aluminum concentration 7 g / L).
Anodization was performed at a current density of A / dm 2 to form an anodized film having an average film thickness of 6 μm. Next, after washing with water, a high-temperature sealant top seal DX-500 (produced by Okuno Pharmaceutical Co., Ltd.) containing nickel acetate as a main component was immersed in a 10 g / L aqueous solution at 95 ° C. for 30 minutes for sealing treatment. Subsequently, after washing with water, the coated surface was reciprocated 8 times using a polyester sponge and rubbed. Finally, it was washed with water and dried to obtain a substrate having a surface roughness Ra = 0.14 μm.

Next, oxy having main diffraction peaks at Bragg angles (2θ ± 0.2 °) of 9.6 °, 24.1 °, and 27.2 ° with respect to CuKα characteristic X-ray (wavelength 1.541Å) as a charge generation material. Titanium phthalocyanine (20 parts) and 1,2-dimethoxyethane (280 parts) were mixed and pulverized in a sand grind mill for 1 hour for atomization and dispersion treatment. Subsequently, 15 parts of polyvinyl butyral (trade name “Denkabutyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.), 445 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl-2-pentanone 1
A dispersion liquid (charge generating material) was prepared by mixing a binder resin liquid obtained by mixing 06 parts, the above-mentioned fine treatment liquid, and 230 parts of 1,2-dimethoxyethane.

An aluminum cylinder that has been subjected to the anodizing treatment and sealing treatment is dip coated on this dispersion (charge generating material), and the electric charge is adjusted so that the film thickness after drying is 0.4 μm (0.4 g / m ² ). A generation layer was prepared.
Next, 40 parts of the following compound CT-1 as a charge transport material, 100 parts of a polyarylate resin (viscosity average molecular weight of about 70,000) consisting of repeating units of the following structure as a binder resin,

4 parts of a compound having the structure

0.1 part of a compound having the structure

0.5 parts of compound having the following structure

And a charge transport layer coating solution prepared by dissolving 0.05 part of silicone oil (trade name: KF96 Shin-Etsu Chemical Co., Ltd.) as a leveling agent in 640 parts of a tetrahydrofuran / toluene (8/2) mixed solvent. On the generation layer, dip coating was performed so that the film thickness after drying was 18 μm, and drying was performed at 135 ° C. for 20 minutes to obtain a photosensitive drum 1 having a laminated photosensitive layer.

[Example 2]
A photosensitive drum 2 was obtained in the same manner as in Reference Example 1 except that 40 parts of the following structural formula CT-2 was used as the charge transport material in Reference Example 1.

[Example 3]
A photosensitive drum 3 was obtained in the same manner as in Reference Example 1 except that 40 parts of the following structural formula CT-3 was used as the charge transport material in Reference Example 1.

[ Reference Example 4]
In Reference Example 1, 45 parts of CT-1 as a charge transport material, and polyarylate resin (viscosity average molecular weight of about 86,
000) A photoconductor 4 was obtained in the same manner as in Reference Example 1 except that 100 parts were used.

[Example 5]
In Reference Example 1, 45 parts of CT-2 as a charge transport material, and polyarylate resin (viscosity average molecular weight of about 86,
000) A photoconductor 5 was obtained in the same manner as in Reference Example 1 except that 100 parts were used.

[ Reference Example 6]
In Reference Example 1, Photoreceptor 6 was prepared in the same manner as Reference Example 1 except that the charge generating material was 20 parts and polyvinyl butyral (trade name “Denka Butyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) 25 parts. Got.

[Comparative Example 1]
Reference Example 1, 20 parts of a charge generation material, a polyvinyl butyral (Denki Kagaku Kogyo Co., Ltd., trade name "Denka Butyral"# 6000C) except for using 10 parts, in the same manner as in Reference Example 1, the photosensitive member A Got.

[Comparative Example 2]
In Comparative Example 1, in the same manner except that the pre-Symbol formula CT-2 and 40 parts of Comparative Example 1 as a charge transporting material, to obtain a photosensitive member B.

[Comparative Example 3]
In Comparative Example 1, in the same manner except that the pre-Symbol structural formula CT-3 and 40 parts of Comparative Example 1 as a charge transporting material, to obtain a photosensitive member C.

[Comparative Example 4]
In Comparative Example 1, a photoconductor C was obtained in the same manner as in Comparative Example 1, except that 40 parts of the following structural formula CT-4 was used as the charge transport material.

[Comparative Example 5]
In Comparative Example 1, except that 45 parts of CT-1 was used as a charge transport material, and 100 parts of a polyarylate resin (viscosity average molecular weight of about 86,000) consisting of a repeating unit of the above structure as a binder resin of the charge transport layer, In the same manner as in Comparative Example 1, a photoreceptor D was obtained.

[Comparative Example 6]
In Comparative Example 1, except that 45 parts of CT-3 was used as the charge transport material, and 100 parts of polyarylate resin (viscosity average molecular weight of about 86,000) consisting of repeating units of the above structure was used as the binder resin of the charge transport layer, In the same manner as in Comparative Example 1, a photoreceptor E was obtained.

[Evaluation of Photosensitive Drum]
Above Examples 2, 3, 5, Reference Examples 1, 4, 6, and a photoreceptor drum obtained in Comparative Example 1-6
To about, and the results are shown in Table 2 were evaluated the following evaluation items.
(1) Electrical characteristics
Set the charging conditions so that V0 = 700 (-V), and measure the potential 0.06 seconds after exposure.
VL: exposure energy: 0.7μJ / cm ² measured at 2 environment potential 25 ° C. 50% RH and 10 ° C. 15% RH after irradiation (2) adhesive
Cut 6 squares on a 5mm square, affix the tape to the drum surface, fold the tape at 90 degrees, pull it off with the finger in the drum axis direction, and count the number of peeled photosensitive layers.

Claims (5)

In an electrophotographic photosensitive member having at least a charge generation layer and a charge transport layer on a conductive support, the charge generation layer contains a charge generation material and a polyvinyl acetal resin as a binder resin, and all binder resins in the charge generation layer The mass ratio of the charge generating material to [the charge generating material / total binder resin] wr is 0.4 ≦ wr ≦ 1.4, and the charge transport layer includes the charge transport material and the binder resin, and the total charge transport The content of the substance is all binder resin 10 in the charge transport layer.
32 to 50 parts by mass with respect to 0 part by mass, and the charge transport material has the following structural formula CT-2 and
An electrophotographic photoreceptor , which is at least one compound of the structural formula CT-3 .

The binder resin of the charge transport layer is a polyarylate resin having a structure represented by the following general formula (I) as a diol component and a structure represented by the following general formula (II) as a dicarboxylic acid component The electrophotographic photosensitive member according to claim 1.

(In Formula (I), Ar ¹ and Ar ² each independently represent an arylene group optionally having a substituent, X represents a single bond or a divalent linking group, and in Formula (II), , Ar ³ and Ar ⁴ each independently represent an optionally substituted arylene group, Y represents each independently a single bond or a divalent linking group, and k represents an integer of 0 or more. .) The conductive support is subjected to anodizing treatment and sealing treatment.
Or the electrophotographic photosensitive member according to 2. The electrophotographic photosensitive member according to any one of claims 1 to 3, charging means for charging the electrophotographic photosensitive member, and image exposure is performed on the charged electrophotographic photosensitive member to form an electrostatic latent image. An electrophotographic cartridge comprising: an image exposure unit; a developing unit that develops the electrostatic latent image with toner; and a transfer unit that transfers the toner to a transfer target. The electrophotographic photosensitive member according to claim 1, a charging unit that charges the electrophotographic photosensitive member, and an exposure unit that forms an electrostatic latent image by exposing the charged electrophotographic photosensitive member. And a developing unit that develops the electrostatic latent image with toner, a transfer unit that transfers the toner to a transfer target, and a fixing unit that fixes the toner transferred to the transfer target. An image forming apparatus.

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