JP2011095418A - Electrophotographic photoreceptor, electrophotographic cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which hardly causes defective cleaning, filming, staining, lowering in density or the like, and to provide an electrophotographic cartridge and an image forming apparatus which use the electrophotographic photoreceptor and do not cause blade inversion and the generation of sliding friction sound upon the printing. <P>SOLUTION: The electrophotographic photoreceptor contains a polyarylate resin having a repeated structure of a specific structure and a triarylamine-stilbene conjugated charge transport substance of a specific structure in a photoreceptor layer. The electrophotographic cartridge and the image forming apparatus which use the electrophotographic photoreceptor are also provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, an electrophotographic cartridge, and an image forming apparatus.

  In recent years, the use of image forming apparatuses such as electrophotographic copying machines has been expanded, and the market demand for image quality has been increasing. In particular, in office documents, in addition to the development of mapping technology and latent image forming technology for input, the types of character hieroglyphics are more abundant and finer at the time of output. Due to the spread and development, the reproducibility of a latent image with extremely high image quality that has few defects and unclearness in printed images is required.

To cope with high image quality, it is effective to reduce the particle size of the toner. This technology is good at chemical toners, and various toners have been developed (Patent Documents 1 and 2).
In addition, many various charge transport materials have been proposed as efforts to improve the sensitivity of the photoreceptor, reduce the residual potential, and improve the response (Patent Documents 3 and 4). For improving the durability of the photoreceptor, polycarbonate resin has been often used as a binder resin for the surface layer of the electrophotographic photoreceptor, but in recent years, by using a polyarylate resin with high mechanical strength, Proposals for improving durability have been made (Patent Documents 5 and 6).

JP 2001-134005 A Japanese Patent Laid-Open No. 11-147331 Japanese Patent Publication No. 63-019867 JP-A-3-075666 Japanese Patent Laid-Open No. 10-039521 JP 2006-053549 A

  As a problem in the case of using a conventional chemical toner, it is mentioned that when the toner shape is close to a sphere, the toner slips between the photosensitive member and the blade, resulting in poor cleaning. Therefore, when chemical toner is used, a method of increasing the contact pressure of the cleaning blade and suppressing defective cleaning is often used. However, in this case, other problems such as blade reversal and rubbing noise are likely to occur. This problem is particularly remarkable when a suspension polymerization toner having a large circularity is used.

As described above, in the prior art, the potential of the chemical toner has not been sufficiently extracted.
The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photosensitive member with less cleaning failure, filming, dirt, afterimage (ghost), density reduction and the like. Another object of the present invention is to provide an electrophotographic cartridge and an image forming apparatus that do not generate blade reversal and rubbing noise during printing using this electrophotographic photosensitive member.

As a result of intensive studies to solve the above problems, the present inventors have found that the photosensitive layer contains a specific polyarylate resin and a specific stilbene-based charge transporting material, resulting in poor cleaning, filming, and contamination. In addition, an electrophotographic photosensitive member with little afterimage (ghost), density reduction, etc. can be provided, and by using this electrophotographic photosensitive member, an electrophotographic cartridge that does not cause blade reversal or rubbing noise during printing is provided. In addition, the present inventors have found that an image forming apparatus can be provided and completed the present invention.

  That is, the first gist of the present invention is an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer includes a polyarylate resin having a repeating structure represented by the following formula [1]: And an electrophotographic photoreceptor comprising at least a compound represented by the following formula [6].

(In the formula [1], Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or the following formula [2]. A group or a group represented by the following formula [3], wherein k represents an integer of 0 or more, and Y is a single bond, an oxygen atom, a sulfur atom, or a group represented by the following formula [5]. is there.)

(In the formula, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² may be bonded to form a ring.)

(R ³ in the formula is an alkylene group, an arylene group, or a group represented by the following formula [4].)

(In the formula, R ⁴ and R ⁵ each independently represents an alkylene group, and Ar ⁵ represents an arylene group.)

(In the formula, R ⁶ and R ⁷ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, and R ⁶ and R ⁷ may be bonded to form a ring.)

(In the formula [6], Ar ⁶ and Ar ⁷ are phenyl groups having a substituent constant σp in the Hammett rule of 0.20 or less and having at least one substituent having 1 to 4 carbon atoms, or in the Hammett rule. A substituent constant σp is 0.20 or less and represents an aromatic condensed polycyclic hydrocarbon group which may have a substituent having 1 to 4 carbon atoms, and R is a carbon number having 2 to 4 carbon atoms. Represents an alkyl group, A and B may be the same or different and each represents a substituent having 1 to 4 carbon atoms having a substituent constant σp of 0.20 or less in Hammett's rule, and m and n each represent 0 to 4 Indicates an integer.)
The second gist of the present invention is the above-described electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, and image exposure for forming an electrostatic latent image by performing image exposure on the charged electrophotographic photosensitive member. Developing means for developing the electrostatic latent image with toner; transfer means for transferring the toner from the electrophotographic photosensitive member to the transfer target; and removing toner remaining on the electrophotographic photosensitive member after transfer. An electrophotographic cartridge is provided with at least one of cleaning means.

At this time, it is preferable to have a blade cleaning mechanism, and it is preferable that the blade cleaning mechanism is a counter contact system.
Further, the average circularity of the toner measured by a flow type particle image analyzer is preferably 0.945 or more and 1.000 or less.
The third gist of the present invention is to form an electrostatic latent image by performing image exposure on the electrophotographic photosensitive member described above, charging means for charging at least the electrophotographic photosensitive member, and the charged electrophotographic photosensitive member. An image forming apparatus 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.

At this time, it is preferable to have a blade cleaning mechanism, and it is preferable that the blade cleaning mechanism is a counter contact system.
Further, the average circularity of the toner measured by a flow type particle image analyzer is preferably 0.945 or more and 1.000 or less.

According to the present invention, it is possible to provide an electrophotographic photosensitive member with little cleaning failure, filming, dirt, afterimage (ghost), density reduction and the like. Also, by using this electrophotographic photosensitive member, it is possible to provide an electrophotographic cartridge and an image forming apparatus that do not generate blade reversal and rubbing noise during printing.

It is the graph which showed the load curve with respect to indentation depth. 1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. It is an X-ray diffraction diagram showing a powder X-ray diffraction spectrum of oxytitanium phthalocyanine used to adjust the coating solution L for forming a charge generation layer used in Examples and Comparative Examples of the present invention. FIG. 3 is an X-ray diffraction diagram showing a powder X-ray diffraction spectrum of oxytitanium phthalocyanine used for preparing the charge generation layer forming coating solution M used in Examples and Comparative Examples of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following contents, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
[1. Electrophotographic photoreceptor]
The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a conductive support and a photosensitive layer formed on the conductive support, and the photosensitive layer is represented by at least the general formula [1]. And a triarylamine-stilbene conjugated charge transport material represented by the general formula [6].

[1-1. Conductive support]
Examples of the conductive support used in the photoreceptor of the present invention include a metal material such as aluminum, aluminum alloy, stainless steel, copper, and nickel; and a conductive powder added with conductive powder such as metal, carbon, and tin oxide. Mainly used are resin, glass, paper, and the like obtained by depositing or coating a conductive material such as aluminum, nickel, and ITO (indium tin oxide) on the surface. In addition, a conductive support body may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

For example, a drum shape, a sheet shape, a belt shape, or the like is used. A conductive support made of a metal material may be coated with a conductive material having an appropriate resistance value for controlling conductivity, surface properties, etc., and covering defects.
When a metal material such as an aluminum alloy is used as the conductive support, a conductive support surface with an anodized film may be used. 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 composition is immersed in an aqueous solution containing nickel acetate as a component is preferable.

The concentration of nickel fluoride in the nickel fluoride aqueous solution used in the case of the low-temperature sealing treatment is arbitrary as long as the effects of the present invention are not significantly impaired, but usually 3 g / L or more, and usually 6 g / L 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 processing 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 later for improving adhesiveness, blocking property and the like. As the undercoat layer, for example, a resin, a resin in which particles such as a metal oxide are dispersed, or the like is used. The undercoat layer may be a single layer or a plurality of layers.

  Examples of the metal oxide particles contained in 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, and calcium titanate. And metal oxide particles containing a plurality of metal elements such as strontium titanate and barium titanate. One of these may be used alone, or two or more thereof may be used in any ratio and combination.

Among these metal oxide particles, titanium oxide or aluminum oxide is 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 silicone. Any one of these treatments may be used, or two or more thereof may be applied.

As the crystal form of the titanium oxide particles, for example, any of rutile, anatase, brookite, and amorphous can be used. In addition, the titanium oxide particles may have only one crystal type, or two or more crystal types may be included in any ratio and combination.
The particle size of the metal oxide particles is arbitrary as long as the effects of the present invention are not significantly impaired, but the average primary particle size is usually from the viewpoint of the properties of the binder resin, which is the raw material for the undercoat layer, and the stability of the solution. A thickness of 10 nm or more, preferably 20 nm or more, and usually 100 nm or less, preferably 50 nm or less is desirable. This average primary particle size can be measured by, for example, a transmission electron microscope (TEM) photograph.

  The undercoat layer is preferably formed by dispersing metal oxide particles in a binder resin. Such an undercoat layer is, for example, a solution in which metal oxide particles are dispersed in a solution in which a binder resin is dissolved, and the metal oxide particles are dispersed (hereinafter referred to as “undercoat layer forming coating solution” as appropriate). ) Is preferably applied. Examples of the binder resin used for the undercoat layer include 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. , Vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacrylic acid resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, nitrocellulose, etc. Cellulose ester resin, cellulose ether resin, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, zirconium chelate compound, Organozirconium compounds such as benzalkonium alkoxide compounds, titanyl chelate compounds, organic titanyl compounds such as titanyl alkoxide compound, silane coupling agent, and the like. One of these may be used alone, or two or more thereof may be used in any ratio and combination. Moreover, you may use with the shape hardened with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamide, modified polyamide, and the like are preferable because they exhibit good dispersibility and coating properties.

The amount of the metal oxide particles used is arbitrary as long as the effects of the present invention are not significantly impaired. From the viewpoint of the stability of the coating liquid for forming the undercoat layer and the coating properties,
The amount is usually 10 parts by weight or more and usually 500 parts by weight or less.
When the metal oxide particles are contained in the undercoat layer forming coating solution, the metal oxide particles are usually present dispersed in the coating solution. As a method for dispersing the metal oxide particles in the coating liquid for forming the undercoat layer, for example, a known mechanical grinding device such as a ball mill, a sand grind mill, a planetary mill, or a roll mill is used. Can be dispersed. Among these, it is preferable to disperse using a dispersion medium.

  As a dispersion device when dispersing using a dispersion medium, any known dispersion device may be used. For example, a pebble mill, a ball mill, a sand mill, a screen mill, a gap mill, a vibration mill, Examples include paint shakers and attritors. Among these, those capable of being dispersed by circulating the coating solution are preferable, and a sand mill, a screen mill, and a gap mill are used from the viewpoints of dispersion efficiency, fineness of the reached particle diameter, ease of continuous operation, and the like. The sand mill may be either a vertical type or a horizontal type. The disc shape of the sand mill can be any plate type, vertical pin type, horizontal pin type or the like.

Since the dispersion medium is usually in the shape of a perfect sphere, the average particle diameter is, for example, JIS.
It can be determined by a method of sieving with a sieve described in ring Z 8801: 2000, for example, image analysis using an image analysis apparatus such as LU ring ZEX50 manufactured by Nireco Corporation.
The density can be measured by, for example, the Archimedes method.

Further, the sphericity can be obtained by an image analysis device such as LU ring ZEX50 manufactured by Nireco Corporation.
The average particle size of the dispersion medium is usually 5 μm or more, preferably 10 μm or more, and the upper limit is usually 200 μm or less, preferably 100 μm. Generally, by using a dispersion medium having a small particle size, there is a tendency to give a uniform dispersion in a short time. However, if the particle size becomes too small, the mass of the dispersion medium becomes small and efficient dispersion is achieved. May not be possible.

For example, in order to disperse the titanium oxide particles in the coating solution for the undercoat layer, a dispersion medium having various average particle diameters can be used. Among them, it is preferable to use a dispersion medium having an average particle diameter in the above range. .
The density of the dispersion medium is usually 5.5 g / cm ³ or more, preferably 5.9 g / cm ³ or more, more preferably 6.0 g / cm ³ or more. In general, when a dispersion medium having a higher density is used for dispersion, a uniform dispersion tends to be obtained in a shorter time.

The sphericity of the dispersion medium is preferably 1.08 or less, more preferably 1.07 or less.
As the dispersion medium, any medium can be used as long as the effects of the present invention are not significantly impaired. Thus, it is preferable that it does not react with the coating solution for forming the undercoat layer or alter the coating solution for forming the undercoat layer. Specific examples of dispersion media include steel balls such as chrome balls (ball balls for ball bearings) and carbon balls (carbon steel balls); stainless steel balls; ceramic balls such as silicon nitride balls, silicon carbide, zirconia, and alumina; titanium nitride And spheres coated with a film of titanium carbonitride and the like. Among these, ceramic spheres are preferable, and zirconia fired balls are particularly preferable. More specifically, it is particularly preferable to use zirconia fired beads described in Japanese Patent No. 3400836. One of these may be used alone, or two or more thereof may be used in any ratio and combination.

In the liquid in which the undercoat layer is dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3 (hereinafter, referred to as “dispersion for measuring the undercoat layer” as appropriate), the metal oxide particles are The volume average particle diameter measured by the dynamic light scattering method is usually 20 nm or more, and the upper limit is usually 0.1 μm or less, preferably 95 nm or less, more preferably 90 nm or less. By satisfying the above range, the electrophotographic photosensitive member of the present invention has stable exposure-charging repeat characteristics under low temperature and low humidity, and suppresses occurrence of image defects such as black spots and color spots in the obtained image. it can.

In addition, as a specific measuring method by the dynamic light scattering method, for example, a method described in JP-A-2007-334335 can be used.
Further, the metal oxide particles in the dispersion for measuring the undercoat layer have a cumulative 90% particle diameter measured by a dynamic light scattering method of usually 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more. The upper limit is usually 0.3 μm or less, preferably 0.25 μm or less, more preferably 0.2 μm 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.
[1-3. Photosensitive layer]
As the structure of the photosensitive layer, any structure applicable to a known electrophotographic photoreceptor can be adopted. As a specific example, a so-called single-layer type photoreceptor having a single-layer photosensitive layer in which a photoconductive material is dissolved or dispersed in a binder resin; a charge generation layer containing a charge generation material; and a charge transport material Examples include a so-called multilayer type photoreceptor having a photosensitive layer composed of a plurality of layers formed by laminating a charge transport layer. In general, it is known that the photoconductive material exhibits the same performance as a function regardless of whether it is a single layer type or a laminated type.

The photosensitive layer possessed by the electrophotographic photoreceptor of the present invention may be in any known form, but taking into account the mechanical properties, electrical characteristics, production stability, etc. of the electrophotographic photoreceptor, 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.
The photosensitive layer in the electrophotographic photoreceptor of the present invention contains at least a polyarylate resin having a specific structure and a specific charge transport material.

[1-3-1. Polyarylate resin]
The photosensitive layer in the electrophotographic photoreceptor of the present invention contains a polyarylate resin having a repeating structure represented by the following formula [1] (hereinafter referred to as “polyarylate resin [1]” as appropriate). In addition, polyarylate resin [1] may be used individually by 1 type, and may use 2 or more types by arbitrary ratios and combinations.

(In the formula [1], Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or the following formula [2]. A group or a group represented by the following formula [3], wherein k represents an integer of 0 or more, and Y is a single bond, an oxygen atom, a sulfur atom, or a group represented by the following formula [5]. is there.)

(In the formula, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² may be bonded to form a ring.)

(R ³ in the formula is an alkylene group, an arylene group, or a group represented by the following formula [4].)

(In the formula, R ⁴ and R ⁵ each independently represents an alkylene group, and Ar ⁵ represents an arylene group.)

(In the formula, R ⁶ and R ⁷ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, and R ⁶ and R ⁷ may be bonded to form a ring.)
<Structure>
In the above formula [1], Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent. 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, More preferably, it is 6. If the number of carbon atoms is too large, the production cost increases and the electrical characteristics may also deteriorate.

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

Specific examples of the substituents for Ar ^{1 to} Ar ⁴ include an alkyl group, an aryl group, a halogen group, and an alkoxy group. Among them, considering the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the alkyl group is preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, and is preferably an aryl group. Is preferably a phenyl group or a naphthyl group, a halogen group is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and an alkoxy group is preferably a methoxy group, an ethoxy group, a propoxy group or a butoxy group.

In addition, when a substituent is an alkyl group, carbon number of the alkyl group is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 2 or less.
More specifically, Ar ³ and Ar ⁴ each independently preferably has a substituent number of 0 or more and 2 or less, more preferably has a substituent from the viewpoint of adhesion, and among these, substitution from the viewpoint of wear resistance. It is particularly preferable that the number of groups is one. Moreover, as a substituent, an alkyl group is preferable and a methyl group is particularly preferable.

From the above viewpoint, at least one of Ar ³ and Ar ⁴ is preferably an arylene group having a substituent.
On the other hand, Ar ¹ and Ar ² 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 formula [1], X is a single bond, an oxygen atom, a sulfur atom, a group represented by the following formula [2], or a group represented by the following formula [3], R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² may be bonded to form a ring such as a cycloalkylidene group. R ^{3 in} [3] is an alkylene group, an arylene group, or a group represented by the following formula [4], and R ⁴ and R ^{5 in} formula [4] are each independently an alkylene group. Ar ⁵ represents an arylene group.

In Formula [1], preferred X includes an oxygen atom, a sulfur atom, a structure represented by Formula [2], or a divalent organic residue having a structure represented by Formula [3].
Examples of the alkyl group of R ¹ and R ² in the formula [2] include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. In addition, examples of the cycloalkylidene group formed by combining R ¹ and R ² in the formula [2] include a cyclopentylidene group, a cyclohexylidene group, and a cycloheptylidene group. Furthermore, examples of the alkylene group represented by R ³ in the formula [3] include a methylene group, an ethylene group, and a propylene group. Examples of the arylene group represented by R ³ in the formula [3] include a phenylene group and a terphenylene group. Specific examples of the group represented by the formula [4] include a group represented by the following formula [7].

Among these, X is preferably an oxygen atom.
In the above formula [1], Y is a single bond, an oxygen atom, a sulfur atom, or a group represented by the following formula [5].

R ⁶ and R ⁷ in the formula [5] each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a cycloalkylidene group formed by combining R ⁶ and R ⁷ . Considering the mechanical properties as the binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, R ⁶ and R ⁷ in the formula [5] are preferably phenyl groups and naphthyl groups as aryl groups, As an alkoxy group, a methoxy group, an ethoxy group, and a butoxy group are preferable. Moreover, as an alkyl group, a C1-C10 alkyl group is preferable, More preferably, it is C1-C8, Most preferably, it is C1-2. Considering the simplicity of production of the divalent hydroxyaryl component used in producing the polyarylate resin, Y is a single bond, —O—, —S—, —CH ₂ —, —CH (CH ₃ ) —. , —C (CH ₃ ) ₂ — and cyclohexylene are preferable, and —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ — and cyclohexylene are particularly preferable. CH ₂ — and —CH (CH ₃ ) —.

In the present invention, the polyarylate resin [1] is preferably a polyarylate resin having a repeating structure represented by the following general formula [8]. In the following general formula [8], Ar ^{16 to} Ar ¹⁹ each independently represent an arylene group which may have a substituent, and R ⁸ represents a hydrogen atom or an alkyl group.

In the general formula [8], Ar ^{16 to} Ar ¹⁹ respectively correspond to the Ar ^{1 to} Ar ⁴ and particularly preferably a phenylene group which may have a substituent. Moreover, as a preferable substituent, it is a hydrogen atom or an alkyl group, Most preferably, it is a methyl group. Further, in the general formula [8], Ar ¹⁸ and Ar ¹⁹ are phenylene groups having a methyl group, and Ar ¹⁶ and Ar ¹⁷ are particularly preferably phenylene groups having no substituent. R ⁸ represents a hydrogen atom or an alkyl group. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably a methyl group.

<Divalent hydroxyaryl residue>
The divalent hydroxyaryl component to be a divalent hydroxyaryl residue in the polyarylate resin is represented by the following general formula [9], but is preferably represented by the following general formula [10].

Ar ³ , Ar ⁴ and Y in the general formula [9] are as described above.

Ar ¹⁸ , Ar ¹⁹ and R ⁸ in the general formula [10] are as described above.
Specifically, when R ⁸ in the general formula [10] is a hydrogen atom, bis (2-hydroxyphenyl) methane, (2-hydroxyphenyl) (3-hydroxyphenyl) methane, (2-hydroxyphenyl) ( 4-hydroxyphenyl) methane, bis (3-hydroxyphenyl) methane, (3-hydroxyphenyl) (4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) methane, bis (2-hydroxy-3-methylphenyl) Methane, bis (2-hydroxy-3-ethylphenyl) methane, (2-hydroxy-3-methylphenyl) (3-hydroxy-4-methylphenyl) methane, (2-hydroxy-3-ethylphenyl) (3- Hydroxy-4-ethylphenyl) methane, (2-hydroxy-3-methylphenyl) (4-hydroxy) Ci-3-methylphenyl) methane, (2-hydroxy-3
-Ethylphenyl) (4-hydroxy-3-ethylphenyl) methane, bis (3-hydroxy-4-methylphenyl) methane, bis (3-hydroxy-4-ethylphenyl) methane, (3-hydroxy-4-methyl) Phenyl) (4-hydroxy-3-methylphenyl) methane, (3-hydroxy-4-ethylphenyl) (4-hydroxy-3-ethylphenyl) methane, bis (4-hydroxy-3-methylphenyl) methane, bis (4-hydroxy-3-ethylphenyl) methane.

When R ⁸ is a methyl group, 1,1-bis (2-hydroxyphenyl) ethane, 1- (2-hydroxyphenyl) -1- (3-hydroxyphenyl) ethane, 1- (2-hydroxyphenyl) ) -1- (4-hydroxyphenyl) ethane, 1,1-bis (3-hydroxyphenyl) ethane, 1- (3-hydroxyphenyl) -1- (4-hydroxyphenyl) ethane, 1,1-bis ( 4-hydroxyphenyl) ethane, 1,1-bis (2-hydroxy-3-methylphenyl) ethane, 1,1-bis (2-hydroxy-3-ethylphenyl) ethane, 1- (2-hydroxy-3-) Methylphenyl) -1- (3-hydroxy-4-methylphenyl) ethane, 1- (2-hydroxy-3-ethylphenyl) -1- (3-hydroxy-4-ethylphenyl) Enyl) ethane, 1- (2-hydroxy-3-methylphenyl) -1- (4-hydroxy-3-methylphenyl) ethane, 1- (2-hydroxy-3-ethylphenyl) -1- (4-hydroxy) -3-ethylphenyl) ethane, 1,1-bis (3-hydroxy-4-methylphenyl) ethane, 1,1-bis (3-hydroxy-4-ethylphenyl) ethane, 1- (3-hydroxy-4) -Methylphenyl) -1- (4-hydroxy-3-methylphenyl) ethane, 1- (3-hydroxy-4-ethylphenyl) -1- (4-hydroxy-3-ethylphenyl) ethane, 1,1- Bis (4-hydroxy-3-methylphenyl) ethane and 1,1-bis (4-hydroxy-3-ethylphenyl) ethane are mentioned.

Among these, in the case where R ⁸ in the general formula [10] is a hydrogen atom, bis (4-hydroxyphenyl) methane, (2-hydroxyphenyl) is considered in consideration of the ease of production of the divalent hydroxyaryl component. (4-Hydroxyphenyl) methane, bis (2-hydroxyphenyl) methane, bis (4-hydroxy-3-methylphenyl) methane, and bis (4-hydroxy-3-ethylphenyl) methane are particularly preferred. It is also possible to use a combination of a plurality of hydroxyaryl components.

In addition, when R ⁸ in the general formula [10] is a methyl group, 1,1-bis (4-hydroxyphenyl) ethane, 1- (2-hydroxyphenyl) -1- (4-hydroxyphenyl) ethane 1,1-bis (2-hydroxyphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) ethane, and 1,1-bis (4-hydroxy-3-ethylphenyl) ethane are particularly preferable. A combination of a plurality of these divalent hydroxyaryl components can also be used.

Although general formula [10] is contained in general formula [9], the compound of general formula [9] other than the illustration of the said general formula [10] is also demonstrated below.
Specific examples of the divalent hydroxyaryl component represented by the general formula [9] include 3,3 ′, 5
, 5'-tetramethyl-4,4'-dihydroxybiphenyl, 2,4,3 ', 5'-tetramethyl-3,4'-dihydroxybiphenyl, 2,2', 4,4'-tetramethyl-3 , 3′-dihydroxybiphenyl, bis (4-hydroxy-3,5-dimethylphenyl) ether, (4-hydroxy-3,5-dimethylphenyl) (3-hydroxy-2,4-dimethylphenyl) ether, bis ( 3-hydroxy-2,4-dimethylphenyl) ether, bis (4-hydroxy-3,5-dimethylphenyl) methane, (4-hydroxy-3,5-dimethylphenyl) (3-hydroxy-2,4-dimethyl Phenyl) methane, bis (3-hydroxy-2,4-dimethylphenyl) methane, 1,1-bis (4-hydroxy-3,
5-dimethylphenyl) ethane, 1- (4-hydroxy-3,5-dimethylphenyl) -1- (3-hydroxy-2,4-dimethylphenyl) ethane, 1,1-bis (3-hydroxy-2, 4-dimethylphenyl) ethane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2- (4-hydroxy-3,5-dimethylphenyl) -2- (3-hydroxy-2, 4-dimethylphenyl) propane, 2,2-bis (3-hydroxy-2,4-dimethylphenyl) propane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) cyclohexane, 1- (4- Hydroxy-3,5-dimethylphenyl) -1- (3-hydroxy-2,4-dimethylphenyl) cyclohexane, 1,1-bis (3-hydroxy-2,4-di Tilphenyl) cyclohexane, preferably 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenyl, bis (4-hydroxy-3,5-dimethylphenyl) ether, 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-bis (4-hydroxy-3,5-dimethylphenyl) cyclohexane. Alternatively, bis (2-hydroxyphenyl) ether, (2-hydroxyphenyl) (3-hydroxyphenyl) ether, (2-hydroxyphenyl) (4-hydroxyphenyl) ether, bis (3-hydroxyphenyl) ether, (3 -Hydroxyphenyl) (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ether, bis (2-hydroxy-3-methylphenyl) ether, bis (2-hydroxy-3-ethylphenyl) ether, (2- Hydroxy-3-methylphenyl) (3-hydroxy-4-methylphenyl) ether, (2-hydroxy-3-ethylphenyl) (3-hydroxy-4-ethylphenyl) ether, (2-hydroxy-3-methylphenyl) ) (4-Hydroxy-3-methylphenyl) Ether, (2-hydroxy-3-ethylphenyl) (4-hydroxy-3-ethylphenyl) ether, bis (3-hydroxy-4-methylphenyl) ether, bis (3-hydroxy-4-ethylphenyl) ether, (3-hydroxy-4-methylphenyl) (4-hydroxy-3-methylphenyl) ether, (3-hydroxy-4-ethylphenyl) (4-hydroxy-3-ethylphenyl) ether, bis (4-hydroxy- 3-methylphenyl) ether, bis (4-hydroxy-3-ethylphenyl) ether, bis (4-hydroxyphenyl) methane, (2-hydroxyphenyl) (4-hydroxyphenyl) methane, bis (2- Hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) ketone, bis (4-hydroxyphenyl) ether, bis (4-hydroxy -3-methylphenyl) methane, 1,1-bis (4-hydroxy-3-methylphenyl) ethane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4- Hydroxy-3-methylphenyl) cyclohexane, bis (4-hydroxy-3-methylphenyl) ether, 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-2,3,5-trimethylphenyl) phenylmethane, 1,1-bis (4-hydroxy-2,3,5-trimethylphenyl) ) Phenylethane, bis (4-hydroxyphenyl) -1-phenylmethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -1-phenylpropane Bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) methoxymethane, 1,1-bis (4-hydroxyphenyl) -1-methoxyethane, 1,1- Bis (4-hydroxyphenyl) -1-methoxypropane, bis (4-hydroxy Eniru) dimethoxymethane, and the like.

Among these, bis (4-hydroxy-3,5-dimethylphenyl) methane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) are considered in consideration of the ease of production of the divalent hydroxyaryl component. Propane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) cyclohexane, or bis (4-hydroxyphenyl) ether, (2-hydroxyphenyl) (4-hydroxyphenyl) ether, bis (2- Hydroxyphenyl) ether, bis (4-hydroxy-3-methylphenyl) ether, and bis (4-hydroxy-3-ethylphenyl) ether are particularly preferable, and a combination of a plurality of these divalent hydroxyaryl components can be used. is there.

<Dicarboxylic acid residue>
The dicarboxylic acid component which is a dicarboxylic acid residue in the polyarylate resin is represented by the following general formula [11].

Ar ¹ , Ar ² , X, and k in the general formula [11] are as described above, and the dicarboxylic acid residues contained in the formula [11] are represented by the following general formulas [I] to [VI]. Examples of structures that can be illustrated. Here, k is an integer of 0 or more, but an integer of 0 to 5 is preferable from the viewpoint of electrical characteristics and scratch resistance, and more preferably 0 or 1.

Preferably, k is 1 and X is an oxygen atom, and is represented by the following general formula [12].

Ar ¹⁶ and Ar ¹⁷ in the general formula [12] are also as described above, and are preferably phenylene groups having no substituent.
Specific examples of the preferred dicarboxylic acid residue represented by the general formula [12] include diphenyl ether-2,2′-dicarboxylic acid residue, diphenyl ether-2,3′-dicarboxylic acid residue, diphenyl ether-2,4 ′. -Dicarboxylic acid residue, diphenyl ether-3,3'-dicarboxylic acid residue, diphenyl ether-3,4'-dicarboxylic acid residue, diphenyl ether-4,4'-dicarboxylic acid residue and the like. Among these, considering the simplicity of production of the dicarboxylic acid component, diphenyl ether-2,2′-dicarboxylic acid residue, diphenyl ether-2,4′-dicarboxylic acid residue, diphenyl ether-4,4′-dicarboxylic acid Residues are more preferred, and diphenyl ether-4,4′-dicarboxylic acid residues are particularly preferred.

Specific examples of the dicarboxylic acid residue represented by the general formula [11] other than the above include phthalic acid residue, isophthalic acid residue, terephthalic acid residue, toluene-2,5-dicarboxylic acid residue, p Xylene-2,5-dicarboxylic acid residue, naphthalene-1,4-dicarboxylic acid residue, naphthalene-2,3-dicarboxylic acid residue, naphthalene-2,6-dicarboxylic acid residue, biphenyl-2,2 '-Dicarboxylic acid residue, biphenyl-4,4'-dicarboxylic acid residue can be mentioned, preferably phthalic acid residue, isophthalic acid residue, terephthalic acid residue, naphthalene-1,4-dicarboxylic acid residue , Naphthalene-2,6-dicarboxylic acid residue, biphenyl-2,2′-
A dicarboxylic acid residue, a biphenyl-4,4′-dicarboxylic acid residue, particularly preferably
It is an isophthalic acid residue or a terephthalic acid residue, and it is also possible to use a combination of these dicarboxylic acid residues.

The polyarylate resin may be a resin containing another dicarboxylic acid component and enclosing the general formula [11] in a part of the structure. Specific examples of other dicarboxylic acid residues include adipic acid residues, suberic acid residues, sebacic acid residues, pyridine-2,3-dicarboxylic acid residues, pyridine-2,4-dicarboxylic acid residues, pyridine -2,5-dicarboxylic acid residue, pyridine-2,6-dicarboxylic acid residue, pyridine-3,4-dicarboxylic acid residue, pyridine-3,5-dicarboxylic acid residue, preferably, These are adipic acid residues and sebacic acid residues, and a plurality of these dicarboxylic acid residues can be used in combination.

  In addition, when it has the dicarboxylic acid residue [11] constituting the present invention and the above-mentioned other dicarboxylic acid residues, the dicarboxylic acid residue constituting the present invention is 70% or more as the number of repeating units. Is preferable, 80% or more is more preferable, and 90% or more is particularly preferable. Most preferably, it has only the dicarboxylic acid residue [11] constituting the present invention, that is, the dicarboxylic acid residue [11] constituting the present invention is 100% as the number of repeating units.

<Physical properties>
In the polyarylate resin having a repeating structure represented by the general formula [1], the viscosity average molecular weight is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 10,000 or more, more preferably 20,000. In addition, the upper limit is preferably 70,000 or less, more preferably 50,000 or less. If the value of the viscosity average molecular weight is too small, the mechanical strength of the polyarylate 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. 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 polyarylate resin described above is used in an electrophotographic photoreceptor, and is used as a binder resin in a photosensitive layer provided on a conductive support of the photoreceptor.
[1-3-2. Charge transport material]
The triarylamine-stilbene conjugated charge transport material of the present invention is a compound represented by the following general formula [6].

In the formula [6], Ar ⁶ and Ar ⁷ are a phenyl group having a substituent constant σp of 0.20 or less in Hammett's rule and having at least one substituent having 1 to 4 carbon atoms, or substitution in Hammett's rule A group constant σp of 0.20 or less and an aromatic condensed polycyclic hydrocarbon group which may have a substituent having 1 to 4 carbon atoms, wherein R is an alkyl having 2 to 4 carbon atoms Indicates a group. A and B may be the same or different and each represents a substituent having 1 to 4 carbon atoms having a substituent constant σp in the Hammett rule of 0.20 or less, and m and n each represents an integer of 0 to 4.

Examples of the substituent for Ar ⁶ or Ar ⁷ include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a dialkylamino group having 2 to 4 carbon atoms, and the like. Examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, methoxy, ethoxy, propoxy, butoxy, N, N-dimethylamino, N, N-diethylamino and the like. Among these, a substituent having 1 to 2 carbon atoms is particularly preferable from the viewpoint of electrical characteristics and production cost.

  Here, the Hammett's rule is an empirical rule used to explain the effect of a substituent in an aromatic compound on the electronic state of the aromatic ring, and the substituent constant σp of the substituted benzene is the electron donation of the substituent. / It can be said that the degree of suction is quantified. If the σp value is positive, the substituted benzoic acid is more acidic than the unsubstituted one, that is, an electron-withdrawing substituent. Conversely, when the σp value is negative, an electron donating substituent is formed. Table 1 shows σp values of representative substituents (The Chemical Society of Japan, “Chemical Handbook, Basic Edition II, 4th revised edition”, Maruzen Co., Ltd., published on September 30, 1993, p.364-365). .

In the general formula [6], examples of Ar ⁶ and Ar ⁷ include phenyl, naphthyl, fluorenyl, anthryl, phenanthryl, and pyrenyl. From the viewpoint of production cost, a phenyl group is particularly preferable.

In the general formula [6], as A and B, the substituent constant σp in Hammett's rule is 0.20 or less, preferably a substituent having 1 to 4 carbon atoms, and an alkyl group having 1 to 2 carbon atoms. More preferably, they may be the same or different. Examples thereof include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a dialkylamino group having 2 to 4 carbon atoms, and specifically include methyl, ethyl, n-propyl, isopropyl, n -Butyl, isobutyl, tert-butyl, methoxy, ethoxy, propoxy, butoxy, N, N-dimethylamino, N, N-diethylamino and the like. Among these, a substituent having 1 carbon atom is particularly preferable from the viewpoint of electrical characteristics and production cost.

In the general formula [6], m and n are each an integer of 0 to 4, and an integer of 0 to 1 is preferable, but from the viewpoint of manufacturing cost, m = n = 0 is particularly preferable.
In the general formula [6], R is an alkyl group having 2 to 4 carbon atoms, and examples thereof include ethyl, n-propyl, isopropyl, n-butyl, and isobutyl groups. From the viewpoint of electrical characteristics and production cost, R is particularly preferably an ethyl group, an n-propyl group or an isopropyl group. When the number of carbon atoms is 2 to 4, an electrophotographic photoreceptor having good charge transport material solubility and good electrical characteristics can be obtained.

The molecular weight of the general formula [6] is usually 500 or less, preferably 460 or less. When this range is satisfied, the cleaning performance is improved when the actual image is evaluated, and it is easy to prevent noise and filming. This is presumably because the surface hardness of the photoreceptor is high by using a low molecular charge transport material. Therefore, in the general formula [6], it is particularly preferable to adjust the substituents Ar ⁶ and Ar ⁷ and R, X, Y, m, and n in view of the molecular weight. On the other hand, the lower limit is preferably 400 or more from the viewpoint of electrical characteristics.

  Usually, when a polyarylate resin is used as the binder resin, abnormal noise due to rubbing with the cleaning blade tends to occur. However, this can be suppressed by combining the polyarylate resin of the present invention and the triarylamine-stilbene conjugated charge transport material. Further, when these are combined and contained in the photosensitive layer, an electrophotographic photoreceptor excellent in abrasion resistance can be produced with little cleaning failure, filming, dirt, afterimage (ghost), density reduction and the like. The reason for this is not clear, but according to the study by the present inventors, it is considered that a charge transport material having a lower molecular weight has an effect of improving the slipperiness of the photoreceptor surface when combined with a polyarylate resin.

  The triarylamine-stilbene conjugated charge transporting material of the present invention may be used in combination with other charge transporting materials, but in order to fully exhibit the effects of the present invention, the total charge transporting contained in the photosensitive layer is possible. In the material, the amount of the charge transport material of the present invention is usually 30% by weight or more, preferably 50% by weight or more, more preferably 80% by weight or more, and particularly preferably 100% by weight.

  Further, the triarylamine-stilbene conjugated charge transport material of the present invention is usually 30 parts by weight or more, preferably 40 parts by weight with respect to 100 parts by weight of the binder resin in order to sufficiently exert the effects of the present invention. Above, more preferably 50 parts by weight or more, and the upper limit thereof is preferably 120 parts by weight or less, more preferably 100 parts by weight or less, and particularly preferably 80 parts by weight or less.

  In addition, the triarylamine-stilbene conjugated charge transport material of the present invention exhibits particularly excellent effects when it is contained in the photosensitive layer together with the polyarylate resin of the present invention. When the polyarylate resin is used, the electrical characteristics are usually deteriorated as compared with the case of using the polycarbonate resin, but the triarylamine-stilbene conjugated charge transport material of the present invention and the polyarylate resin are used in combination. In this case, both excellent wear resistance and electrical characteristics can be achieved.

Representative examples of the triarylamine-stilbene conjugated charge transport material represented by the general formula [6] of the present invention include the following exemplified compounds CT-1 to CT-21. However, the charge transport material according to the present invention is not limited to these compounds.

  These stilbene derivatives can be easily synthesized by known methods. For example, the exemplified compound CT-1 of the present invention can be produced according to the following reaction formula.

As described above, p-bromobenzyl bromide (A) is added to triethyl phosphite and heated to 90-95 ° C. to obtain the phosphoric acid ester derivative (B) (Wordsworth reagent). (B) and p-alkoxybenzaldehyde (C) are dissolved in dimethylformamide (hereinafter referred to as DMF) solvent and condensed by adding a base to produce a stilbene derivative (D). Finally, (D) and the diarylamine derivative (E) are coupled in the presence of a palladium-tri (o-tolyl) phosphine complex to obtain the charge transport material CT-1 as the target product.

[1-3-3. Binder resin other than polyarylate resin]
The photosensitive layer in the electrophotographic photosensitive member of the present invention contains at least a polyarylate resin represented by the above general formula [1] and a charge transport material represented by the general formula [6]. However, the binder resin may include a resin other than the polyarylate resin represented by the general formula [1]. In this case, the polyarylate resin of the present invention is usually 30% by weight or more, preferably 50% by weight or more in all binder resins used in the charge transport layer of the multilayer photoreceptor and the photosensitive layer of the single-layer photoreceptor. The amount is preferably 80% by weight or more, particularly preferably 100% by weight.

  When forming a charge transport layer of a function-separated type photoconductor having a charge generation layer and a charge transport layer (that is, a multi-layer photoconductor) and a photosensitive layer of a single-layer type photoconductor, The transport material is used by dispersing in a binder resin. The charge transport layer of the functional separation type photoreceptor can be obtained by applying and drying a coating solution obtained by dissolving or dispersing a charge transport material and various binder resins in a solvent. The single-layer type photoreceptor can be obtained by applying and drying a coating solution obtained by dissolving or dispersing a charge generating substance, a charge transporting substance and various binder resins in a solvent.

Examples of the binder resin that can be used in combination with the polyarylate resin represented by the general formula [1] include butadiene resin, styrene resin, vinyl acetate resin, vinyl chloride resin, acrylic ester resin, methacrylic ester resin, and vinyl alcohol. Resins, polymers and copolymers of vinyl compounds such as ethyl vinyl ether, polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyester resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicone resin , Silicone-alkyd resin, poly-N-vinylcarbazole resin and the like. These resins may be modified with a silicon reagent or the like. Of the binder resins, polycarbonate resins are particularly 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.

  As the polycarbonate resin that can be used in combination with the polyarylate resin, a polycarbonate resin having a repeating structure represented by the following formula [13] is preferably used.

(In Formula [13], Ar ²¹ and Ar ²² 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 [13], Ar ²¹ and Ar ²² each independently represent an arylene group which may have a substituent. Examples of the arylene group include a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a naphthylene group, an anthrylene group, and a phenanthrylene group. Groups are preferred.

Specific examples of the substituents for Ar ²¹ and Ar ²² 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 ²¹ and Ar ²² 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 above formula [13], 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 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. Further, among R ^c and R ^d , when 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, Isopropyl group is preferable, aryl group is preferably phenyl group or naphthyl group, halogen group is preferably fluorine atom, chlorine atom, bromine atom or iodine atom, and alkoxy group is methoxy group, ethoxy group, propoxy group or 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.

Examples of the diol component that forms these structures include bisphenol compounds and biphenol compounds.
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-methyl Pentane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) bisphenol compounds having no substituents on the aromatic rings such as cyclohexane;
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, etc.
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, etc.
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) 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-hydride) Xyl-2,3,5-trimethylphenyl) ethane, 2,2-bis (4-hydroxy-2,3,5-trimethylphenyl) propane, bis (4-hydroxy-2,3,5-trimethylphenyl) phenyl On aromatic rings such as methane, 1,1-bis (4-hydroxy-2,3,5-trimethylphenyl) phenylethane, 1,1-bis (4-hydroxy-2,3,5-trimethylphenyl) cyclohexane A bisphenol compound having an alkyl group as a substituent;
Bis (4-hydroxyphenyl) (phenyl) methane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -1-phenylpropane, bis (4- Bisphenol compounds in which a divalent group connecting aromatic rings such as hydroxyphenyl) (diphenyl) methane and bis (4-hydroxyphenyl) (dibenzyl) methane has an aryl group as a substituent. In addition, a diol component may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

  Among these, polycarbonate resins formed from bisphenol or biphenol shown below are preferably used.

  In particular, a polycarbonate resin formed from bisphenol having the following structure is preferable.

The polycarbonate resin may contain a polycarbonate structure other than that represented by the above formula [13] as a partial structure. Further, the partial structure may include a structure other than the polycarbonate resin.

  In the above polycarbonate resin, the weight ratio of the partial structure represented by the formula [13] is preferably as large as possible from the viewpoints of electrical characteristics and wear resistance. Specifically, the partial structure represented by the formula [13] is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 80% by weight or more with respect to the total weight of the polycarbonate resin. In particular, it is desirable that the content is 100% by weight.

  The viscosity average molecular weight of the binder resin that can be used in combination with the polyarylate 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 70000. Below, it is desirable that it is 50000 or less. 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. The viscosity average molecular weight can be measured in the same manner as in the case of the polyarylate resin [1].

[1-3-4. Other charge transport materials]
In addition to the triarylamine-stilbene conjugated charge transport material of the present invention, other known charge transport materials may be used in combination. When other charge transport materials are used in combination, the type is not particularly limited. For example, aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, and quinones such as diphenoquinone Electron withdrawing substances such as compounds, carbazole derivatives, indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, heterocyclic compounds such as benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives , Enamine derivatives, and those obtained by bonding a plurality of these compounds, or electron donating substances such as polymers having a group consisting of these compounds in the main chain or side chain. Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, hydrazone derivatives, enamine derivatives, and those in which a plurality of these compounds are bonded are preferable. One of these charge transport materials may be used alone, or two or more thereof may be used in any ratio and combination.

[1-3-5. Charge generation material]
In the present invention, it is preferable to use a charge generating material as necessary. The electrification substance is usually contained in the single-layer photosensitive layer in a single-layer photosensitive layer, and contained in a charge generation layer in a laminated photosensitive layer.
Specific examples of the charge generating substance include, for example, selenium and its alloys, cadmium sulfide, other inorganic photoconductive materials, phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, Various photoconductive materials such as organic pigments such as perylene pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments can be used, and organic pigments, phthalocyanine pigments, and azo pigments are particularly preferable. In addition, a charge generation material may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

Specific examples of the phthalocyanine used include metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, and other metals, or oxides, halides, hydroxides, and alkoxides thereof. Various crystal forms of such coordinated phthalocyanines are used. In particular, titanyl phthalocyanines (also known as oxytitanium) such as X-type, τ-type metal-free phthalocyanine, A-type (also known as β-type), B-type (also known as α-type), and D-type (also known as Y-type), which are highly sensitive crystal types Phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and I, IIS
A μ-oxo-aluminum phthalocyanine dimer such as a mold is preferred. Among these phthalocyanines, A type (β type), B type (α type), D type (Y type) oxytitanium phthalocyanine, II type chlorogallium phthalocyanine, V type hydroxygallium phthalocyanine, G type μ-oxo- Gallium phthalocyanine dimer and the like are particularly preferable. In particular, oxytitanium phthalocyanine preferably has a clear diffraction peak mainly at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray.

The oxytitanium phthalocyanine preferably has a clear diffraction peak at a Bragg angle (2θ ± 0.2 °) of 9.0 ° to 9.7 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-rays. .
Moreover, in the said oxytitanium phthalocyanine, it is preferable that the chlorine content in a crystal | crystallization is 1.5 weight% or less. The chlorine content can be determined by elemental analysis, for example.

  Further, in the oxytitanium phthalocyanine crystal, the ratio of the chlorinated oxytitanium phthalocyanine represented by the following formula [14] is higher than the unsubstituted oxytitanium phthalocyanine represented by the following formula [15]. The ratio is 0.070 or less. The mass spectral intensity ratio is preferably 0.060 or less, more preferably 0.055 or less. In the production, when the dry grinding method is used for amorphization, 0.02 or more is preferable, and when the acid paste method is used for amorphization, 0.03 or less is preferable. The amount of chlorine substitution can be measured based on the method disclosed in Japanese Patent Application Laid-Open No. 2001-115054.

The particle diameter of these oxytitanyl phthalocyanines varies greatly depending on the production method and crystal conversion method, but considering the dispersibility, the primary particle diameter is preferably 500 nm or less, and from the viewpoint of coating film formability, it is preferably 300 nm or less. preferable.

In addition to the chlorine atom, the oxytitanium phthalocyanine may contain various oxytitanium phthalocyanine derivatives substituted with a substituent such as a fluorine atom, a nitro group, a cyano group, or a sulfone group. In addition, these substituents may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.
As the azo pigment, various known bisazo pigments and trisazo pigments are preferably used. An example of a preferred azo pigment is shown in the following formula [16]. In the following formula [16], Cp ^{1 to} Cp ³ represent couplers.

Above all, in the formula [16], as the coupler ^Cp 1 ~ CP ^3, the following structures are preferred.

Furthermore, by using phthalocyanine and an azo pigment in combination, it is possible to produce an electrophotographic photoreceptor having high sensitivity and no ghost.
Examples of binder resins commonly used for charge generation layers in functionally separated photoreceptors include polyvinyl butyral resins, polyvinyl formal resins, partially acetalized polyvinyl butyral resins in which a portion of butyral is modified with formal, acetal, etc. Polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, modified ether polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, polyacrylamide Resin, polyamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casei And vinyl chloride-vinyl chloride-vinyl acetate copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, etc. Vinyl acetate copolymers, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, styrene-alkyd resins, silicone-alkyd resins, insulating resins such as phenol-formaldehyde resins, poly-N-vinylcarbazole, It can be selected and used from organic photoconductive polymers such as polyvinyl anthracene and polyvinyl perylene, but is not limited to these polymers. These binder resins may be used alone or in combination of two or more.

  In the charge generation layer of the functional separation type photoreceptor, the mixing ratio of the binder resin and the charge generation material is usually 10 parts by weight or more, preferably 30 parts by weight or more, and the upper limit thereof with respect to 100 parts by weight of the binder resin. Is usually 1000 parts by weight or less, preferably 500 parts by weight or less. If the amount used is too small, the sensitivity as an electrophotographic photosensitive member may be lowered, and if too much, the stability of the coating solution may be lowered due to aggregation of charge generating substances.

The film thickness is usually 0.1 μm or more, preferably 0.15 μm or more, and the upper limit is usually 4 μm or less, preferably 0.6 μm or less.
The method for forming the charge generation layer is arbitrary as long as the effects of the present invention are not significantly impaired. However, in the case of a laminated type photoreceptor, a coating solution for forming a charge generation layer in which a charge generation material is dispersed is usually applied and dried. Thus, it can be formed.

As a method for dispersing the charge generating substance, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, a sand mill dispersion method, or an ultrasonic dispersion method can be used. At this time, it is desirable to make the particles finer to a particle size of usually 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.
[1-3-6. 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 property, flexibility, coating property, 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 surfactants include silicone oil and fluorine oil.
Examples of the hindered phenol antioxidant include 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-ethylphenol, and 2,6-di-t-butyl-4-methyl. Phenol, 2,2′-methylenebis (6-tert-butyl-4-methylphenol), 4,4′-butylidenebis (6-tert-butyl-3-methylphenol), 4,4′-thiobis (6-t -Butyl-3-methylphenol), 2,2′-butylidenebis (6-tert-butyl-4-methylphenol), α-tocopherol, β-tocopherol, 2,2,4-trimethyl-6-hydroxy-7- t-butylchroman, pentaerythrityltetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2′-thioethylenebis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], 1,6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], butylhydroxyanisole, dibutyl Hydroxyanisole, 1- [2-{(3,5-di-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- [3- (3,5-di-butyl-4-hydroxyphenyl) propionyloxy ] -2,2,6,6-tetramethylpiperazyl, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5 Triazine, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 2- (5-methyl- -Hydroxyphenyl) benzotriazole, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 1- [2- {3- (3,5-di-t-butyl) -4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, n -Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, etc. can be mentioned.

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 with respect 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, it is possible to easily produce an electrophotographic photoreceptor free from fog 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.
[1-4. Protective layer]
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.
[1-5. Layer formation method]
Each layer constituting the photoconductor is usually obtained by applying a coating solution containing the material constituting each layer on the support using a known coating method, repeating the coating and drying processes for each layer, and sequentially applying the coating liquid. It is formed.

Solvents used for preparing the coating solution and dispersion medium for dissolving the binder resin, for example, saturated aliphatic solvents such as pentane, hexane, octane, nonane,
Aromatic solvents such as toluene, xylene, anisole,
Halogenated aromatic solvents such as chlorobenzene, dichlorobenzene, chloronaphthalene,
Amide solvents such as dimethylformamide and N-methyl-2-pyrrolidone,
Alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, benzyl alcohol,
Aliphatic polyhydric alcohols such as glycerin and polyethylene glycol,
Chain, branched and cyclic ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, 4-methoxy-4-methyl-2-pentanone,
Ester solvents such as methyl formate, ethyl acetate, n-butyl acetate,
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 Linear and cyclic ether solvents such as sorb,
Aprotic polar solvents such as acetonitrile, dimethyl sulfoxide, sulfolane, hexamethylphosphoric triamide,
nitrogen-containing compounds such as n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, triethylenediamine, triethylamine,
Mineral oil such as ligroin,
Examples thereof include water, 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 the charge transport layer of a single layer type photoreceptor or a multilayer photoreceptor, the coating liquid for layer formation has a solid content concentration of usually 5% by weight or more, preferably 10% by weight or more, and the upper limit is The amount is usually 40% by weight or less, preferably 35% by weight 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 concentration is usually 0.1% by weight or more, preferably 1% by weight or more, and the upper limit is usually 15% by weight or less, preferably 10% by weight. It is.
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.

The coating solution can be dried by touching at room temperature (usually 25 ° C.), followed by heating and drying in the temperature range of usually 30 ° C. or more and 200 ° C. or less, usually for 1 minute or more and 2 hours or less, without wind or air. preferable. The heating temperature may be constant or may be changed while drying.
The thickness of the photosensitive layer of the single-layer type photoreceptor is usually 5 μm or more, preferably 10 μm or more, and the upper limit is usually 100 μm or less, preferably 50 μm or less.

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.
[1-6. Physical properties of photosensitive layer]
<Elastic deformation rate and universal hardness>
The elastic deformation rate of the surface of the electrophotographic photoreceptor of the present invention is usually 42% or more, preferably 43% or more, more preferably 44.5% or more, particularly preferably 45% or more, and the upper limit is usually 60%. Hereinafter, it is preferably 50% or less. As the elastic deformation rate is larger, the scratch resistance of the photosensitive layer is improved, and filming caused by pressing silica or the like used as an external additive of the toner against the cleaning blade tends to be improved. However, if the elastic deformation rate is too large, there is a possibility that a rubbing noise with the cleaning blade is likely to occur.

Further, the universal hardness of the present invention is usually 150 N / mm ² or more, preferably 160 N / mm ² or more, more preferably 170N / mm ² or more, and the upper limit thereof is usually 300N / mm ² or less, preferably 270N / mm ² or less, more preferably 250 N / mm ² or less.
The elastic deformation rate and the universal hardness in the present invention are values measured under an environment of a temperature of 25 ° C. and a relative humidity of 50% using a microhardness meter FISHERSCOPE H100C manufactured by Fischer. For the measurement, a Vickers square pyramid diamond indenter having a facing angle of 136 ° is used. The measurement conditions are set as follows, and the load applied to the indenter and the indentation depth under the load are continuously read, and profiles as shown in FIG. 1 plotted on the Y axis and the X axis are obtained.

[Measurement condition]
Maximum indentation load 1mN
Load required time 27 seconds Unloading required time 27 seconds The above elastic deformation rate is a value defined by the following equation, and the work performed by the film due to elasticity at the time of unloading with respect to the total work amount required for indentation. It is a ratio.

Elastic deformation rate (%) = (We / Wt) × 100
In the above formula, the total work Wt (nJ) indicates the area surrounded by A-B-D-A in FIG. 1, and the elastic deformation work We (nJ) is the area surrounded by C-B-D-C. Indicates. As the elastic deformation rate is larger, the deformation with respect to the load is less likely to remain, and when the elastic deformation rate is 100, it means that no deformation remains.

Moreover, said universal hardness is a value when it pushes in to the maximum indentation depth of 1 micrometer, and is a value defined by the following formula | equation from the load at that time.
Universal hardness (N / mm ² ) = Test load (N) / Vickers indenter surface area under test load (mm ² )
By using the polyarylate resin [1] and the charge transport material of the present invention in combination, the above elastic modulus and universal hardness can be easily obtained. In particular, in the general formula [1], when a polyarylate resin in which X is an oxygen atom and k = 1 is used, the elastic deformation rate and the universal hardness exhibit particularly preferable characteristics.

[2. toner]
When image formation is performed using the electrophotographic photosensitive member of the present invention, any toner can be used as a toner that is a developer for developing a latent image, and among them, the toner has a specific average circularity. It is particularly preferable to use a toner. By using the toner having a specific circularity as described above, the image forming apparatus of the present invention can form a higher quality image.

<Average circularity>
The shape of the toner of the present invention is such that the shape of each particle included in the particle group constituting the toner is closer to each other, and the closer to a sphere, the less likely the localization of the charge amount in the toner particles occurs. The developability tends to be uniform, which is preferable for improving the image quality. In particular, if the toner has a shape close to a perfect sphere, the contact area with the electrophotographic photosensitive member may be reduced, the toner transfer rate may be increased, and the toner consumption may be reduced. . On the other hand, it is difficult to manufacture a toner having a perfect spherical shape, and the cost of the toner increases. Therefore, it is sufficient that the toner is close to a spherical shape under a certain condition, and it is not necessary to have a perfect spherical shape.

  Specifically, the toner of the present invention has an average circularity measured by a flow particle image analyzer of usually 0.945 or more, preferably 0.960 or more, more preferably 0.975 or more, particularly preferably. 0.980 or more. The upper limit of the average circularity is usually 1.000 or less, preferably 0.998 or less, more preferably 0.995 or less from the viewpoint of ease of production.

The average circularity is used as a simple method for quantitatively expressing the shape of toner particles. In the present invention, the average circularity is measured using a flow type particle image analyzer FPIA-2000 manufactured by Sysmex Corporation. Then, the circularity [a] of the measured particle is obtained by the following formula (X).
Circularity a = L ₀ / L (X)
(In Formula (X), L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image when image processing is performed.)
The circularity is an index of the degree of unevenness of the toner particles, and is 1.000 when the toner is perfectly spherical, and the circularity becomes smaller as the surface shape becomes more complicated.

  A specific method for measuring the average circularity is as follows. That is, a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 20 mL of water from which impurities in the container have been removed in advance, and about 0.05 g of a measurement sample (toner) is further added. The suspension in which the sample is dispersed is irradiated with ultrasonic waves for 30 seconds, the dispersion concentration is set to 3000 / μL or more and 8000 / μL or less, and the flow type particle image measuring apparatus is used to measure 0.60 to 160 μm. The circularity distribution of particles having an equivalent circle diameter is measured.

[3. Image forming apparatus and electrophotographic cartridge]
Next, an embodiment of an image forming apparatus (hereinafter referred to as “image forming apparatus of the present invention” as appropriate) using the electrophotographic photoreceptor of the present invention (hereinafter referred to as “photosensitive body” as appropriate) will be described. A description will be given with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily changed and implemented without departing from the gist of the present invention.

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

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

The type of the exposure device 3 is not particularly limited as long as it can expose the photosensitive member 1 to form an electrostatic latent image on the photosensitive surface of the photosensitive member 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, the exposure may be performed using monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light with a wavelength shorter than 380 nm to 500 nm. . 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. Also, the writing resolution is currently 600dp
Although i is the mainstream, there are some 1200 dpi high-performance models. 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. 2, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which the toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. This replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge. In the present embodiment, it is preferable to use the toner of the present invention as the toner T. That is, the toner T used in the image forming apparatus of the present invention is preferably a toner having an average circularity of 0.945 or more and 1.000 or less measured by a flow type particle image analyzer.

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 fluororesin, 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 photoreceptor 1 and the supply roller 43, and is in contact with the photoreceptor 1 and the supply roller 43. 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 photoreceptor 1.

The regulating member 45 is formed of a resin blade such as a silicone resin or a urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such a metal blade with a resin. The regulating member 45 abuts against the developing roller 44 and is pressed with a predetermined force against the developing roller 44 by a spring or the like (a general blade linear pressure is 5 to 5).
00 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 photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the photoreceptor 1 onto a recording paper (paper, medium) P. is there.

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

  Among these, a blade cleaning system having a blade cleaning mechanism is preferable because of its simple structure, small size, low cost, and excellent cleaning performance and reliability. The blade cleaning method can be classified into 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 to remove the toner effectively. In particular, when a toner having a high degree of circularity is used, the toner easily slips between the blade and the photosensitive member. The contact method is preferred. The linear pressure of the blade against the photoreceptor is preferably 20 g / cm or more, and preferably 60 g / cm or less.

If the blade is set under the above conditions, rubbing noise may occur between the photoconductor and the blade, but this can be avoided by using the photoconductor of the present invention.
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. 2 shows an example in which a heating device 73 is provided inside the upper fixing member 71. Each of the upper and lower fixing members 71 and 72 includes a fixing roll in which a metal base tube made of stainless steel, aluminum or the like is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, a fixing sheet, or the like. A member can be used. Further, the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve the releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

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

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

The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.
When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.
In addition to the above-described configuration, the image forming apparatus may have a configuration capable of performing, for example, a static elimination process. The charge eliminating step is a step of discharging the photosensitive member by exposing the photosensitive member, and a fluorescent lamp, LED, or the like is used as the discharging 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.

In addition, 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 photosensitive member 1 and at least one of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, and the cleaning device 6 are combined to form an integrated cartridge (hereinafter referred to as “electrophotographic cartridge” as appropriate). The electrophotographic cartridge may be configured to be detachable from a main body of an image forming apparatus such as a copying machine or a laser beam printer. In this case, for example, when the photosensitive member 1 or other member deteriorates, the electrophotographic cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic cartridge is attached to the main body of the image forming apparatus. Maintenance and management become easy.

When configured as an electrophotographic cartridge, and the electrophotographic cartridge has the cleaning device 6, the cleaning device 6 preferably has a blade cleaning mechanism. In particular, it is more preferable that the blade cleaning mechanism is a counter contact system.
Further, the toner of the present invention is preferably used as the toner used in the electrophotographic cartridge. That is, the toner T used in the image forming apparatus of the present invention is preferably a toner having an average circularity of 0.945 or more and 1.000 or less measured by a flow type particle image analyzer.

Hereinafter, the present invention will be described in more detail with reference to production examples, examples and comparative examples. In addition, the following examples are shown in order to explain the present invention in detail, and the present invention is not limited to the following examples unless departing from the gist thereof. Note that “parts” used in this example represents “parts by weight” unless otherwise specified.
[Calculation method of viscosity average molecular weight]
The viscosity average molecular weight of the polyarylate resin contained in the charge transport layer was calculated as follows.

The polyarylate resin was dissolved in dichloromethane to prepare a solution having a concentration C of 6.00 [g / L]. The flow time t [s] of the sample solution was measured in a constant temperature water bath set to 20.0 ° C. using an Ubbelohde capillary viscometer with a flow time t ₀ [s] of the solvent (dichloromethane) of 136.16 seconds. . And the viscosity average molecular weight Mv was computed according to the following formula | equation.
a = 0.438 × η _sp +1
η _sp = (t / t ₀ ) −1
t ₀ = 136.16 [s]
b = 100 × η _sp / C
C = 6.00 [g / L]
η = b / a
Mv = 3207 × η ^1.205
[Manufacture of coating solution for charge transport layer formation]
<Production Example 1>
100 parts of a polyarylate resin having the following repeating structure (resin 1, viscosity average molecular weight 43000), 80 parts of the CT-1 as a charge transport material, and 8 parts of a compound (AOX1) represented by the following formula as an antioxidant Then, 0.05 part of silicone oil as a leveling agent was dissolved in 640 parts of a mixed solvent of THF / toluene (8/2 (weight ratio)) to prepare a coating solution for forming a charge transport layer.

<Production Example 2>
A charge transport layer forming coating solution was prepared in the same manner as in Production Example 1 using CT-2 instead of CT-1 used in the charge transport layer forming coating solution of Production Example 1.
<Production Example 3>
A coating solution for forming a charge transport layer was prepared in the same manner as in Production Example 1 using CT-3 instead of CT-1 used for the coating solution for forming a charge transport layer in Production Example 1.

<Production Example 4>
Manufacture except that the polyarylate resin (resin 2, viscosity average molecular weight 43200) having the following repeating structure was used instead of the polyarylate resin (resin 1) used in the charge transport layer forming coating solution of Production Example 1. In the same manner as in Example 1, a coating solution for forming a charge transport layer was prepared.

<Production Example 5>
A polyarylate resin (resin 3, viscosity average molecular weight 43,200) having the following repeating structure was used in place of the polyarylate resin (resin 1) used in the charge transport layer forming coating solution of Production Example 1. In the same manner as in Production Example 1, a coating solution for forming a charge transport layer was prepared.

<Production Example 6>
50 parts by weight of the polyarylate resin (resin 1) used in the coating liquid for forming the charge transport layer of Production Example 1 and 50 parts by weight of a polycarbonate resin (resin 4, viscosity average molecular weight 50000) having the following repeating structure: A coating solution for forming a charge transport layer was prepared in the same manner as in Production Example 1, except that it was used.

<Production Example 7>
Manufacture except that polyarylate resin (resin 5, viscosity average molecular weight 41000) having the following repeating structure was used instead of polyarylate resin (resin 1) used in the charge transport layer forming coating solution of Production Example 1. In the same manner as in Example 1, a coating solution for forming a charge transport layer was prepared.

<Production Example 8>
Instead of the polyarylate resin (resin 1) used in the coating liquid for forming the charge transport layer in Production Example 1, a U-polymer (resin 6) manufactured by Unitika Ltd. was used, and THF / toluene (8/2 (weight ratio)). A coating solution for forming a charge transport layer was prepared in the same manner as in Production Example 1, except that dichloroethane was used in place of the mixed solvent (because gelation of the coating solution occurred in the THF / toluene mixed solvent).

<Comparative Production Example 1>
A coating liquid for forming a charge transport layer was prepared in the same manner as in Production Example 1 using Compound CT-22 represented by the following formula instead of CT-1 used for the coating liquid for forming a charge transport layer in Production Example 1. However, turbidity was generated in the liquid, and CTM crystal precipitation was observed.

<Comparative Production Example 2>
Instead of the polyarylate resin (resin 1) used in the coating liquid for forming the charge transport layer in Production Example 1, a polycarbonate resin (resin 7, viscosity average molecular weight 40,00) having the following repeating structure:
A coating solution for forming a charge transport layer was prepared in the same manner as in Production Example 1 except that 0) was used.

<Comparative Production Example 3>
In place of CT-1 used in the charge transport layer forming coating solution of Production Example 1, a compound CT-23 represented by the following formula was used to prepare a charge transport layer forming coating solution in the same manner as in Production Example 1. did.

<Comparative Production Example 4>
In place of CT-1 used for the charge transport layer forming coating solution in Production Example 1, a compound CT-24 represented by the following formula was used to prepare a charge transport layer forming coating solution in the same manner as in Production Example 1. did.

<Comparative Production Example 5>
Instead of CT-1 used in the coating liquid for forming the charge transport layer in Production Example 1, a compound CT-25 represented by the following formula was used to prepare a coating liquid for forming the charge transport layer in the same manner as in Production Example 1. did.

<Example 1>
On the aluminum cylinder having a mirror-finished outer diameter of 30 mm, length of 260.5 mm, and wall thickness of 0.75 mm, the following undercoat layer forming coating solution, charge generating layer forming coating solution, and charge transport layer The undercoat layer, the charge generation layer, and the charge transport layer are formed so that the coating liquid for formation is sequentially applied by a dip coating method, and the film thickness after drying is 1.3 μm, 0.4 μm, and 25 μm, respectively. A photoreceptor drum was obtained.

[Manufacture of coating solution for forming undercoat layer]
The undercoat layer forming coating solution was prepared as follows. Rutile type titanium oxide having an average primary particle size of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by mass of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were used in a Henschel mixer. The surface-treated titanium oxide obtained by mixing was dispersed by a ball mill in a mixed solvent having a methanol / 1-propanol weight ratio of 7/3 to obtain a surface-treated titanium oxide dispersed slurry. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (F)] / bis (4-amino-
3-methylcyclohexyl) methane [compound represented by the following formula (G)] / hexamethylenediamine [compound represented by the following formula (H)] / decamethylene dicarboxylic acid [compound represented by the following formula (J) ] / Octadecamethylene dicarboxylic acid [compound represented by the following formula (K)]
After stirring and mixing the copolyamide pellets having a composition molar ratio of 60% / 15% / 5% / 15% / 5% with heating, the polyamide pellets are dissolved and then subjected to ultrasonic dispersion treatment. By performing the measurement, the weight ratio of methanol / 1-propanol / toluene is 7/1/2 and the surface-treated titanium oxide / copolymerized polyamide is contained at a weight ratio of 3/1. A layer forming coating solution was prepared.

[Manufacture of coating solution for forming charge generation layer]
The charge generation layer forming coating solution was prepared as follows. As a charge generation material, 20 parts of oxytitanium phthalocyanine and 280 parts of 1,2-dimethoxyethane showing the X-ray diffraction spectrum by CuKα characteristic X-rays in FIG. 3 are mixed, and pulverized and dispersed in a sand grind mill for 1 hour. Processing was performed. Subsequently, 10 parts of polyvinyl butyral (trade name “Denka Butyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) was added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl. A binder liquid obtained by dissolving in 85 parts of 2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a coating solution L for forming a charge generation layer.

  As a charge generation substance, 20 parts of oxytitanium phthalocyanine and 280 parts of 1,2-dimethoxyethane showing the X-ray diffraction spectrum by CuKα characteristic X-ray in FIG. Processing was performed. Subsequently, 10 parts of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denkabutyral” # 6000C) was added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl. A binder liquid obtained by dissolving in 85 parts of 2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a coating solution M for forming a charge generation layer.

The charge generation layer forming coating solution L and the charge generation layer forming coating solution M were mixed at a weight ratio of 8: 2 to prepare a charge generation layer forming coating solution used in this example.
The coating liquid prepared in Production Example 1 was used as the coating liquid for forming the charge transport layer.
The obtained electrophotographic photosensitive drum was subjected to the following electrical property test.
[Electrical characteristics test]
An electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404 to 405) is used, and the photosensitive drum is rotated at a constant rotational speed. It was rotated at 60 rpm, and an electrical property evaluation test was performed by a cycle of charging, exposure, potential measurement, and static elimination. At that time, the photosensitive member was charged so that the initial surface potential was − (minus, the same applies hereinafter) to 700 V, and the light from the halogen lamp was converted to monochromatic light of 780 nm with an interference filter and exposed at 1.0 μJ / cm ² . The post-exposure surface potential after 100 milliseconds (hereinafter sometimes referred to as VL) was measured. In the VL measurement, the time required from the exposure to the potential measurement was set to 100 ms, which was a fast response condition. Further, the half-exposure energy E _1/2 (μJ / cm ² ) required until the photoreceptor surface potential was changed from −700 V to −350 V was obtained. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%. The results obtained are shown in Table 2. In Table 2, “CTM” represents “charge transporting substance”.

[Image characteristics test]
Next, using the photosensitive drum prepared above and the toner T1 having an average particle diameter of 6.0 μm and an average circularity of 0.990, it was mounted on an actual machine and subjected to an image characteristic test.
The image characteristic test was performed using a color printer HP Color LaserJet 4700dn (cleaning blade, counter contact method) manufactured by Hewlett-Packard Company.

The produced photosensitive drum and toner were mounted on a cyan process cartridge, and this cartridge was mounted on a printer. Under the environment of a temperature of 25 ° C. and a humidity of 50%, 10,000 images were formed and evaluated for density reduction, filming, and poor cleaning.
In the image forming apparatus using the electrophotographic photosensitive member of Example 1, a good image without image deterioration such as density reduction, filming, and poor cleaning was obtained before image formation and after 10000-sheet image formation. . In addition, no abnormal noise was generated during printing. The results are also summarized in Table 2.

<Examples 2 to 8>
Instead of the charge transport layer forming coating solution prepared in Production Example 1 used in Example 1, the charge transport layer forming coating solution prepared in Production Examples 2 to 8 was used. Thus, a photoreceptor was manufactured. The electrical property test and the image property test were also performed in the same manner as in Example 1. The results are shown in Table 2.

<Comparative Examples 1-5>
Similar to Example 1 except that the charge transport layer forming coating solution prepared in Comparative Production Examples 1 to 5 was used instead of the charge transport layer forming coating solution prepared in Production Example 1 used in Example 1. Thus, a photoreceptor was produced. The electrical property test and the image property test were also performed in the same manner as in Example 1. The results are shown in Table 2.

<Example 9>
An image characteristic test was conducted in the same manner as in Example 6 except that instead of the toner T1 used in Example 6, a toner T2 having an average particle diameter of 6.0 μm and an average circularity of 0.931 was used. The results are shown in Table 2.

In electrical characteristics, as can be seen from the comparison between Examples 1 to 8 and Comparative Examples 3 to 5 from the results of Table 2, the photoreceptor using the charge transport material of the present invention represented by the general formula [6] is It can be seen that the electrical characteristics are superior to those of the stilbene-based charge transport materials CT-23 to 25 having a similar structure outside the scope of the present invention. In addition, the stilbene-based charge transport material CT-22 has poor compatibility with the binder resin, so that an electrophotographic photoreceptor using it alone has a large amount of crystals precipitated after coating, and almost no light attenuation is observed. Thus, the measurement of characteristics was not achieved (Comparative Example 1).

As can be seen from the comparison between Examples 1 to 8 and Comparative Examples 1 to 5 in Table 2, the polyarylate resin of the present invention and the charge transport material of the present invention represented by the general formula [6] It was found that by using in combination, a good image can be obtained without occurrence of poor cleaning and filming. Among them, it was also found that Ar ³ and Ar ⁴ in the polyarylate resin [1] as the binder resin have a substituent from the viewpoint of releasability (Examples 1 to 6).
reference). In Examples 7 and 8 using a polyarylate resin having no substituent, although the end portion was peeled off, the other portions showed good characteristics. In contrast, polycarbonate resin (resin 7
) Is preferable in terms of electrical characteristics, but poor cleaning and filming occur (see Comparative Example 2).

Furthermore, from the results in Table 2, when the triarylamine-stilbene conjugated charge transport material of the present invention was used, not only the compatibility with the binder resin was good (see Comparative Example 1),
It became clear that abnormal noise during printing could be suppressed. In Comparative Examples 3 and 4, abnormal noise occurs.
In addition, when the polyarylate resin of the present invention is used in combination with a triarylamine-stilbene conjugated charge transport material CT-23 to CT-25 outside the scope of the present invention, the electrical properties are insufficient. A decrease has occurred (see Comparative Examples 3 to 5).

  In addition, when the toner of the present invention is not suitable for the average circularity (0.945 to 1.000) (toner T2, average circularity 0.931), although the electrical characteristics are good, the image quality is good. There was a slight decrease (see Example 9).

  The present invention can be used in any field where an electrophotographic photosensitive member is used, and is particularly suitable for use in an image forming apparatus such as a printer or a copying machine.

1 Photoconductor
2 Charging device (charging roller)
3 Exposure equipment
4 Development device
5 Transfer device
6 Cleaning device
7 Fixing device
41 Developer tank
42 Agitator
43 Supply roller
44 Developing roller
45 Restriction member
71 Upper fixing member (pressure roller)
72 Lower fixing member (fixing roller)
73 Heating device
T Toner
P Recording paper

Claims (8)

In an electrophotographic photosensitive member having a photosensitive layer on a conductive support, the photosensitive layer includes a polyarylate resin having a repeating structure represented by the following formula [1], and a compound represented by the following formula [6]: An electrophotographic photosensitive member comprising at least
(In the formula [1], Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or the following formula [2]. A group or a group represented by the following formula [3], wherein k represents an integer of 0 or more, and Y is a single bond, an oxygen atom, a sulfur atom, or a group represented by the following formula [5]. is there.)
(In the formula, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² may be bonded to form a ring.)
(R ³ in the formula is an alkylene group, an arylene group, or a group represented by the following formula [4].)
(In the formula, R ⁴ and R ⁵ each independently represents an alkylene group, and Ar ⁵ represents an arylene group.)
(In the formula, R ⁶ and R ⁷ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, and R ⁶ and R ⁷ may be bonded to form a ring.)
(In the formula [6], Ar ⁶ and Ar ⁷ are phenyl groups having a substituent constant σp in the Hammett rule of 0.20 or less and having at least one substituent having 1 to 4 carbon atoms, or in the Hammett rule. A substituent constant σp is 0.20 or less and represents an aromatic condensed polycyclic hydrocarbon group which may have a substituent having 1 to 4 carbon atoms, and R is a carbon number having 2 to 4 carbon atoms. Represents an alkyl group, A and B may be the same or different and each represents a substituent having 1 to 4 carbon atoms having a substituent constant σp of 0.20 or less in Hammett's rule, and m and n each represent 0 to 4 Indicates an integer.)   In the formula [1], k is an integer of 0 to 5, and when k is 1 or more, X is an oxygen atom and Y is a group represented by the formula [5]. The electrophotographic photosensitive member according to claim 1.   The electrophotographic photosensitive member according to claim 1 or 2, a charging unit for charging the electrophotographic photosensitive member, an image exposing unit for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image, Developing means for developing the electrostatic latent image with toner, transfer means for transferring the toner from the electrophotographic photosensitive member to a transfer target, and cleaning means for removing the toner remaining on the electrophotographic photosensitive member after transfer An electrophotographic cartridge comprising at least one of the above.   4. The electrophotographic cartridge according to claim 3, further comprising a blade cleaning mechanism, wherein the blade cleaning mechanism is of a counter contact type.   The electrophotographic cartridge according to claim 3 or 4, wherein the toner has an average circularity of 0.945 or more and 1.000 or less as measured by a flow type particle image analyzer.   3. The electrophotographic photosensitive member according to claim 1 or 2, a charging unit for charging at least the electrophotographic photosensitive member, and an image exposing unit for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image. An image forming apparatus comprising: a developing unit that develops the electrostatic latent image with toner; and a transfer unit that transfers the toner to a transfer target.   The image forming apparatus according to claim 6, further comprising a blade cleaning mechanism, wherein the blade cleaning mechanism is of a counter contact type.   8. The image forming apparatus according to claim 6, wherein the average circularity of the toner measured by the flow type particle image analyzer is 0.945 or more and 1.000 or less.