JP2012198520A - Electrophotographic photoreceptor, electrophotographic photoreceptor cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge transport material that exhibits high mobility and sufficient residual potential during exposure for high-speed response, in particular, a charge transport material having high resistance to stress in an electrophotographic process, and an electrophotographic photoreceptor that includes the charge transport material, is excellent in high-speed response, exhibits sufficient residual potential, and has high resistance to stress in an electrophotographic process, as well as an electrophotographic cartridge, and an image forming apparatus.SOLUTION: A charge transport material having a specific structure is provided. In particular, an electrophotographic photoreceptor is provided that has high mobility and exhibits sufficient residual potential during exposure by including the charge transport material having the specific structure into a photosensitive layer of the electrophotographic photoreceptor, and has high resistance to stress in an electrophotographic process.

Description

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

  In recent years, electrophotographic technology has been widely applied not only to the field of copying machines, but also to various printers and printing machines, because of its excellent immediacy and high quality images. As a photoreceptor that is the core of electrophotographic technology, conventionally, a photoreceptor using an inorganic photoconductive material such as selenium, an arsenic-selenium alloy, and zinc oxide has been used, but recently, it is pollution-free. Photoconductors using organic photoconductive materials, which have advantages such as easy film formation / manufacturing and high freedom of material selection / combination, are the mainstream.

  As a layer structure of the organic photoreceptor, a so-called single-layer photoreceptor in which a charge generation material is dispersed in a binder resin, and a laminated photoreceptor in which a charge generation layer and a charge transport layer are laminated are known. Multilayer photoconductors can provide highly sensitive and stable photoconductors by combining highly efficient charge generation materials and charge transport materials into separate layers and combining them optimally. It is often used because it is easy to adjust.

  In recent years, both copying machines and printers are moving from monochrome to full color. This full-color image forming method mainly includes a tandem method and a four-cycle method, and a transfer method to a printing medium includes a direct transfer method, a transfer drum method, an intermediate transfer method, a multiple development batch transfer method, and the like. Among these, tandem systems, that is, color image forming apparatuses that form each color image with separate image forming units and transfer them sequentially, have a wide variety of usable recording materials, have high full color quality, and high speed. It is an excellent image forming method because a full-color image can be obtained. Among them, the characteristic that a full color image can be obtained at high speed is an advantage not seen in other systems.

With the increase in speed and full color of the electrophotographic process as described above, it is essential to increase the sensitivity and speed of response as the characteristics of the electrophotographic photoreceptor. To provide an electrophotographic photoreceptor that satisfies these characteristics. There is a need for the development of highly functional charge transport materials that exhibit high mobility and sufficient residual potential upon exposure. In order to solve these problems, research on charge transport materials in which a styryl group or the like is substituted on the tetraphenylbenzidine skeleton to expand the π-electron system has been actively conducted, and many reports have been made. (Patent Documents 1 to 4)
The photosensitive layer of an electrophotographic photoreceptor using an organic material can be obtained by dissolving a charge transport material, a binder resin, etc. in a coating solvent, and coating and drying the resulting coating solution. A point required for the charge transport material when producing this electrophotographic photosensitive member is solubility in a coating solvent used in the production of a coating solution. If the solubility in the coating solvent is low, the amount of the desired charge transporting material cannot be dissolved in the coating solvent, or the coating solution such as precipitation is likely to deteriorate after dissolving the charge transporting material and producing the coating solution. Further, after coating the photosensitive layer, crystal precipitation may occur in the coating film, or the production efficiency of the coating solution / photosensitive member may be reduced.

In general, a compound in which a π-electron system is expanded in a molecule tends to increase the intermolecular interaction and decrease the solubility as the molecular size increases. The tetraphenylbenzidine skeleton tends to have a large molecular size and low solubility.Substituting this tetraphenylbenzidine skeleton with a styryl group, etc., and expanding the π-electron system within the molecule further increases the molecular size and makes it a coating solvent. The solubility to this is further lowered. Therefore, in the above-mentioned reports, in order to ensure solubility, contrivances such as newly introducing a substituent or handling as a geometric isomer mixture have been made.

JP-A-7-36203 JP 2002-80432 A JP 2006-8670 A JP 2008-83105 A

However, with the above technology alone, in order to reduce the spread of π electrons in the charge transport material molecule due to the influence of the substituent introduced for improving the solubility, or to ensure the solubility, it is intentionally made from the desired structure. In order to obtain a geometric isomer mixture by isomerization, the composition as a whole becomes larger than the desired ionization potential, and there is a problem that the residual potential after exposure increases.

  The present invention has been made in view of the above-described background art, and an object thereof is to provide an electrophotographic photosensitive member, an electrophotographic cartridge, and an image forming apparatus that are excellent in high-speed response and exhibit a sufficient residual potential.

As a result of intensive studies, the present inventor can provide an electrophotographic photosensitive member having a high mobility and a sufficient residual potential upon exposure by incorporating a charge transport material having a specific structure in the photosensitive layer. The inventors have found that this is possible and have completed the present invention described below.
According to a first aspect of the present invention, there is provided an electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, wherein the photosensitive layer contains a charge transport material represented by the following formula (1): It is a photographic photoreceptor.

(In formula (1), R ^{1 to} R ² each independently represents an alkyl group, and R ^{3 to} R ⁹ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group. Represents an integer of 1 to 5, and l and m each independently represents an integer of 1 to 5.
A second invention is an electrophotographic photosensitive member according to the first invention, wherein the compound represented by the formula (1) is a regioisomer mixture.

According to a third invention, in the first invention, the Bragg angle (2θ ± 0.2 °) is at least 24.1 °, 27.2 ° in the powder X-ray diffraction spectrum by CuKα characteristic X-rays on the photosensitive layer.
An electrophotographic photoreceptor comprising a crystalline oxytitanium phthalocyanine having a diffraction peak at a temperature.
According to a fourth aspect of the present invention, there is provided the electrophotographic photosensitive member according to the first aspect of the present invention, a charging unit for charging the electrophotographic photosensitive member, and exposure for forming an electrostatic latent image by exposing the charged electrophotographic photosensitive member. And an at least one selected from the group consisting of a developing unit for developing an electrostatic latent image formed on the electrophotographic photosensitive member.

  According to a fifth aspect of the present invention, there is provided an electrophotographic photosensitive member according to the first aspect of the invention, a charging device for charging the electrophotographic photosensitive member, and an exposure device for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. And a developing device that develops the electrostatic latent image formed on the electrophotographic photosensitive member.

  In the present invention, by incorporating a charge transport material having a specific structure into a photosensitive layer, an electrophotographic photosensitive material having excellent high-speed response, sufficient residual potential, and high resistance to stress in an electrophotographic process. The body can be provided.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. 1 is an X-ray diffraction pattern of oxytitanium phthalocyanine used in Examples. 4 is an IR chart of exemplary compounds CT-7 to 9 obtained in Production Example 1. 6 is an IR chart of Exemplified Compounds CT-10 to 12 obtained in Production Example 2. 6 is an IR chart of exemplary compounds CT-13 to 15 obtained in Production Example 3.

Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and is appropriately modified and implemented without departing from the spirit of the present invention. can do.
<< Electrophotographic Photosensitive Member of the Present Invention >>
<Structure of the charge transport material used in the electrophotographic photoreceptor of the present invention>
The charge transport material used in the electrophotographic photoreceptor of the present invention may be any compound as long as it is a compound represented by the following formula (1).

(In formula (1), R ^{1 to} R ² each independently represents an alkyl group, and R ^{3 to} R ⁹ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group. Represents an integer of 1 to 5, and l and m each independently represents an integer of 1 to 5.
In the above formula (1), R ¹ and R ² each independently represent an alkyl group, and specifically, for example, a straight chain such as a methyl group, an ethyl group, an n-propyl group, or an n-butyl group. And an alkyl group on a branch such as an isopropyl group and an ethylhexyl group, and a cyclic alkyl group such as a cyclohexyl group. Among these alkyl groups, the alkyl group having 1 to 8 carbon atoms is preferable from the versatility of the production raw material, and the alkyl group having 1 to 6 carbon atoms is more preferable from the viewpoint of handling at the time of production. From the viewpoint of light attenuation characteristics as a photoreceptor, an alkyl group having 1 to 4 carbon atoms is more preferable, and from the viewpoint of charge transport ability as a charge transport material, still more preferably 1 to 2 carbon atoms.

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

In the formula (1), R ⁶ and R ⁷ each independently represent any one of a hydrogen atom, an alkyl group, an aryl group, and an alkoxy group. Specifically, examples of the alkyl group include a methyl group, an ethyl group, Examples thereof include linear alkyl groups such as n-propyl group and n-butyl group, branched alkyl groups such as isopropyl group and ethylhexyl group, and cyclic alkyl groups such as cyclohexyl group. The aryl group has a substituent. Phenyl group, naphthyl group and the like which may be used, and as alkoxy group, linear alkoxy group such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, isopropoxy group, ethylhexyloxy A branched alkyl group such as a group, and a cyclohexyloxy group. Among these, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable from the viewpoint of versatility of production raw materials, and a hydrogen atom and carbon number of 1 from the viewpoint of handling at the time of manufacture. More preferable are an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms. From the viewpoint of light attenuation characteristics as an electrophotographic photoreceptor, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms are preferable. Further, an alkyl group having 1 to 4 carbon atoms is particularly preferable from the viewpoint of resistance to ozone of the electrophotographic photoreceptor, and an alkyl group having 1 to 2 carbon atoms is most preferable from the viewpoint of charge transport ability as a charge transport material.

l and m each independently represent an integer of 1 to 5. When l and m represent an integer of 2 or more, the plurality of R ⁶ bonded to the benzene ring may be different from each other, and the plurality of R ⁷ bonded to the benzene ring may also be different from each other.
The substitution position of R ⁶ and R ⁷ can be any position of the o-position, m-position or p-position with respect to the arylamine group, but from the viewpoint of ease of production, the substitution position of the o-position or p-position Either is preferred, and the p-position is more preferred from the viewpoint of light attenuation characteristics of the electrophotographic photosensitive member. In the case where R ⁶ and R ⁷ are a plurality of substituents, the bonding position is usually not limited as long as the effect of the present invention is not significantly impaired. However, from the viewpoint of solubility of the charge transport material, p-position and o Those bonded to the position are preferred.

In the formula (1), R ⁸ and R ⁹ each independently represents a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group, and represents any one of an alkyl group, an aryl group, and an alkoxy group. As the alkyl group, a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group or an n-butyl group, a branched alkyl group such as an isopropyl group or an ethylhexyl group, and a cyclic alkyl group such as a cyclohexyl group are used. The aryl group includes an optionally substituted phenyl group, naphthyl group, and the like. The alkoxy group includes a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, and the like. And a branched alkyl group such as an alkoxy group on a straight chain, an isopropoxy group and an ethylhexyloxy group, and a cyclohexyloxy group. Among these, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable from the viewpoint of versatility of manufacturing raw materials, and from the aspect of resistance to ozone of the electrophotographic photosensitive member, a hydrogen atom and carbon An alkyl group having a number of 1 to 4 is more preferable, and a hydrogen atom is more preferable from the viewpoint of charge transport ability as a charge transport material.

  n represents an integer of 1 to 5. From the viewpoint of improving solubility in a coating solvent, n is preferably 4 or less, more preferably 3 or less from the viewpoint of charge transport ability as a charge transport material, and the light attenuation characteristics of the electrophotographic photosensitive member. From the aspect, it is more preferably 2 or less. Further, from the viewpoint of suppressing the decrease in chargeability of the electrophotographic photosensitive member, it is preferably 2 or more.

  The arylene group part to which the diphenylamino group is bonded is a phenylene group when n = 1, a biphenylene group when n = 2, a terphenylene group when n = 3, a quarterphenylene group when n = 4, In the case of n = 5, it represents a kinkiphenylene group. The position at which two diphenylamino groups are bonded to the arylene group is not limited as long as the effect of the present invention is not significantly impaired. It is preferable that the m-position relationship is established at the bonding position of the phenylene group. In the case of n = 2, it is preferable to bond to the 4-position and 4′-position of the biphenylene group from the viewpoint of charge transport ability as a charge transport material. Of these, a p-terphenylene group is preferable, and the bonding position of the diphenylamine group to the p-terphenylene group is preferably bonded to the 4th and 4 ″ positions from the viewpoint of charge transport ability as a charge transport material. In the case of n = 4, p-quarterphenylene group is preferable among the quarterterphenylene groups from the versatility of the raw materials for production, and the bonding position of the diphenylamine group to the p-terphenylene group is the charge transporting ability as a charge transporting substance. Bonding to the 4th and 4 ′ ″ positions from the surface is preferred. In the case of n = 5, p-kinkiphenylene group is preferable among the kinkiphenylene groups from the versatility of the raw materials for production, and the bonding position of the diphenylamine group to the p-kinkiphenylene group is from the aspect of charge transport ability as a charge transport material. Bonding at the 4th and 4 ″ ″ positions is preferred.

In addition, the electrophotographic photoreceptor of the present invention may usually contain a compound represented by formula (1) as a single component in the photosensitive layer, or a compound having a different structure represented by formula (1). It may be contained as a mixture, and from the viewpoint of manufacturability such as film forming property of the photosensitive layer, a mixture containing a positional isomer of the compound represented by the formula (1) is preferable. In the present invention, when a regioisomer mixture is used, it is more preferably a regioisomer mixture in which the substitution positions of the alkoxy groups composed of R ¹ and R ² are different from the viewpoint of the characteristics of the electrophotographic photoreceptor. The alkoxy group positional isomer mixture usually contains two or more kinds of positional isomers, and the positional isomers contained in the alkoxy group composed of R ¹ and R ² are substituted with respect to the styryl group. It may be an isomer bonded to any of the o-position, m-position and p-position. Among them, from the viewpoint of raw material procurement, at least one of the positional isomers is a positional isomer mixture having an alkoxy group composed of R ¹ or R ² at either the o-position or the p-position with respect to the styryl group. Preferably, in view of manufacturability of the charge transport material, o (R ¹ ) -o (R ² ) form, o (R ¹ ) -p (R ² ) form or p (R ¹ ) -p (R ² ) form It is preferable that the mixture is composed of any two or more positional isomers, and from the viewpoint of charge transport ability as a charge transport material, the mixture is at least p (R ¹ ) -p (R ² ) as a positional isomer. It is more preferable that the mixture includes a isomer, and the mixture is an o (R ¹ ) -o (R ² ) isomer, an o (R ¹ ) -p (R ² ) isomer, and a p (R ¹ ) -p (R ² ). More preferred is a mixture of three positional isomers.

Further, the mixing ratio of the positional isomers in the case of the mixture of positional isomers of the alkoxy group composed of R ¹ and R ² is not particularly limited, but from the viewpoint of the light attenuation characteristics of the electrophotographic photosensitive member, positional isomerism The mixing ratio in which the p (R ¹ ) -p (R ² ) body is most contained in the body mixture is preferable, and specifically, the ratio of the p (R ¹ ) -p (R ² ) body in the mixture is Usually, the lower limit is 35% or more, preferably 40% or more, while the upper limit is usually 75% or less, preferably 60% or less, from the viewpoint of the solubility of the charge transport material.

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

<Method for Producing Charge Transport Material Used for Electrophotographic Photoreceptor of the Present Invention>
The charge transport materials CT1-CT36 exemplified above can be easily synthesized by known methods. For example, the regioisomer mixture consisting of the above-mentioned exemplified CT-10 to 12 of the present invention can be produced according to the scheme described below.
For example, a compound having a tetraphenylbenzidine skeleton can be prepared by formylation by a Vilsmeier reaction or the like and then reacting with a phosphate compound to introduce a styryl group. (Scheme 1)

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

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

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

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

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

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

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

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

<Photosensitive layer>
The photosensitive layer is formed on the above-mentioned conductive support (or on the undercoat layer when the above-described undercoat layer is provided). The photosensitive layer is a layer containing the charge transport material represented by the general formula (1) described above. The charge generation material and the charge transport material (including the charge transport material of the present invention) are the same as the photosensitive layer. A single layer structure in which the charge generation material is dispersed in a binder resin (hereinafter referred to as “single layer type photosensitive layer” as appropriate), a charge generation layer in which a charge generation material is dispersed in a binder resin, and a charge A functionally separated type layered structure composed of two or more layers including a charge transport layer in which a transport material (including the charge transport material of the present invention) is dispersed in a binder resin (hereinafter referred to as “laminated type photosensitive layer” as appropriate). Any form may be used.

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

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

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

When using a phthalocyanine pigment as a charge generation material, specifically, metal such as metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, aluminum, or oxides thereof, halides, Those having each crystal form of coordinated phthalocyanines such as hydroxides and alkoxides, and phthalocyanine dimers using oxygen atoms as bridging atoms are used. 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, hydroxyindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and type I, type II, etc. The [mu] -oxo-aluminum phthalocyanine dimer is preferred.

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

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

The phthalocyanine compound may be a single compound or several mixed or mixed crystal states. As the mixed state in the phthalocyanine compound or crystal state here, those obtained by mixing the respective constituent elements later may be used, or the mixed state in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, crystallization, etc. It may be the one that gave rise to. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known. In order to generate a mixed crystal state, as described in JP-A-10-48859, two types of crystals are mixed, mechanically ground and made amorphous, and then converted into a specific crystal state by solvent treatment. The method of doing is mentioned.
On the other hand, when an azo pigment is used as a charge generation material, various known azo pigments can be used as long as they have sensitivity to a light source for light input. Trisazo pigments are preferably used. Examples of preferred azo pigments are shown below.

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

The binder resin used for the charge generation layer constituting the multilayer photosensitive layer is not particularly limited. For example, polyvinyl butyral resin, polyvinyl formal resin, partially acetalized polyvinyl butyral resin in which part of butyral is modified with formal, acetal, or the like. Polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, modified ether polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, etc. Polyacrylamide resin, polyamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, Vinyl chloride such as zein, vinyl chloride-vinyl acetate copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer -Insulating resin such as vinyl acetate copolymer, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, styrene-alkyd resin, silicon-alkyd resin, phenol-formaldehyde resin, and poly-N-vinylcarbazole , Organic photoconductive polymers such as polyvinyl anthracene and polyvinyl perylene. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.

  Specifically, the charge generation layer is prepared by dispersing a charge generation material in a solution obtained by dissolving the above-described binder resin in an organic solvent to prepare a coating solution, which is then formed on a conductive support (when an undercoat layer is provided). Is formed by coating (on the undercoat layer).

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

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

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

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

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

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

  The binder resin is used for securing the film strength. Examples of the binder resin for the charge transport layer include polymers and copolymers of vinyl compounds such as butadiene resin, styrene resin, vinyl acetate resin, vinyl chloride resin, acrylic ester resin, methacrylic ester resin, vinyl alcohol resin, and ethyl vinyl ether. Polymer, polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyester resin, polyarylate resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicon resin, silicon-alkyd resin, poly-N -Vinyl carbazole resin etc. are mentioned. Of these, polycarbonate resins and polyarylate resins are preferred. These binder resins can also be used after being crosslinked by heat, light or the like using an appropriate curing agent. Any one of these binder resins may be used alone, or two or more thereof may be used in any combination.

The ratio between the binder resin and the charge transport material is 10 parts by mass or more of the charge transport material with respect to 100 parts by mass of the binder resin. Among these, 20 parts by mass or more is preferable from the viewpoint of residual potential reduction, and more preferably 30 parts by mass or more from the viewpoint of stability and charge mobility when repeatedly used. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, the charge transport material is usually used at a ratio of 120 parts by mass or less. Among these, 100 parts by mass or less is preferable from the viewpoint of compatibility between the charge transport material and the binder resin, 90 parts by mass or less is more preferable from the viewpoint of printing durability, and 80 parts by mass or less is most preferable from the viewpoint of scratch resistance.
The thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, on the other hand, usually 50 μm or less, preferably 45 μm or less, from the viewpoint of long life, image stability, and high resolution. Is in the range of 30 μm or less.

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

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

If the amount of the charge generating material dispersed in the single-layer type photosensitive layer is too small, sufficient sensitivity cannot be obtained, but if it is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity. The total amount of the layer-type photosensitive layer is usually 0.5% by mass or more, preferably 1% by mass or more, and usually 50% by mass or less, preferably 20% by mass or less.
In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. It is 30 mass parts or less, Preferably it is set as the range of 10 mass parts or less.
The film thickness of the single-layer type photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less.

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

Further, in both the laminated type photoreceptor and the single layer type photoreceptor, the photosensitive layer formed by the above procedure may be the uppermost layer, that is, the surface layer, but another layer may be provided on the photosensitive layer and used as the surface layer. Good. For example, a protective layer may be provided for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to discharge products generated from a charger or the like.
The protective layer is formed by containing a conductive material in a suitable binder resin, or a copolymer using a compound having charge transporting ability such as a triphenylamine skeleton described in JP-A-9-190004. Can be formed.

Examples of the conductive material used for the protective layer include aromatic amino compounds such as TPD (N, N′-diphenyl-N, N′-bis- (m-tolyl) benzidine), antimony oxide, indium oxide, tin oxide, and oxide. Metal oxides such as titanium, tin oxide-antimony oxide, aluminum oxide, and zinc oxide can be used, but are not limited thereto.
As the binder resin used for the protective layer, known resins such as polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, and siloxane resin can be used. Also, a skeleton having a charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 and a copolymer of the above resin can be used.

The electrical resistance of the protective layer is usually in the range of 10 ⁹ Ω · cm to 10 ¹⁴ Ω · cm. When the electric resistance is higher than the range, the residual potential is increased, resulting in an image with much fogging. On the other hand, when the electric resistance is lower than the range, the image is blurred and the resolution is reduced. Further, the protective layer must be configured so as not to substantially prevent transmission of light irradiated during image exposure.
Further, for the purpose of reducing the frictional resistance and wear on the surface of the photoconductor, and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper, etc., the surface layer is made of fluorine resin, silicon resin, polyethylene resin, You may contain the particle | grains which consist of these resin, and the particle | grains of an inorganic compound. Alternatively, a layer containing these resins and particles may be newly formed as a surface layer.

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

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

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

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

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

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

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

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

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

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

The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicon resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.
The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

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

The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.
The type of the toner T is arbitrary, and in addition to the powdery toner, a polymerized toner using a suspension polymerization method, an emulsion polymerization method or the like can be used. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

  The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

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

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

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

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

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

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

The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.
The electrophotographic photosensitive member 1 is combined with one or more of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6, and the fixing device 7 to form an integrated cartridge ( The electrophotographic photosensitive member cartridge may be configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In this case, for example, when the electrophotographic photosensitive member 1 and other members are deteriorated, the electrophotographic photosensitive member cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic photosensitive member cartridge is mounted on the main body of the image forming apparatus. This facilitates maintenance and management of the image forming apparatus.

<Production of Charge Transport Material Represented by Formula (1)>
(Production Example 1: Regioisomer mixture consisting of Exemplified Compounds CT-7, 8, 9)
A regioisomer mixture consisting of Exemplified Compounds CT-7, 8, 9 was prepared according to Scheme 1 below. Detailed conditions are described below.

Compound A 5 g which is a tetraphenylbenzidine derivative is charged in 50 ml of DMF 60
The temperature was raised to ° C. After raising the temperature, 4.4 g of phosphorus oxychloride was added dropwise at 70 ° C. or lower, and the reaction was carried out in the range of 65 ° C. to 75 ° C. for 4 hours after the completion of the addition. After completion of the reaction, the temperature was lowered to room temperature, and the reaction solution was discharged into a mixed solution of 100 ml of water / 100 ml of toluene for hydrolysis. After hydrolysis, the organic layer was separated, the organic layer was washed with an aqueous sodium hydroxide solution and water until the organic layer became neutral, and the organic layer was concentrated. Then, the concentrated residue was purified by silica gel chromatography to obtain 4.6 g of Compound B which is a tetraphenylbenzidine derivative having a formyl group. (Yield 83.0%)

In 100 ml of THF, 4.8 g of a mixture of positional isomers (compound C: compound D = 68: 32) consisting of 4.6 g of the above formyl compound B and the compound C and compound D which are phosphate ester derivatives was charged and dissolved. After dissolution, 2.2 g of potassium t-butoxy was added and stirred at room temperature for 30 minutes for reaction. After completion of the reaction, the reaction solution is discharged into water, extracted with toluene, the organic layer is concentrated, and the concentrated residue is purified by silica gel chromatography to comprise the charge transport material CT-7, 8, 9 as the target substance. 5.4 g of regioisomer mixture was obtained. (Yield: 83.1%) The composition ratio of the obtained positional isomer mixture consisting of CT-7, 8, and 9 was determined by measuring 1H-NMR (nuclear magnetic resonance). (Composition ratio: CT-7: CT-8: CT-9 = 47: 43: 10)
(Production Example 2: Regioisomer mixture consisting of Exemplified Compounds CT-10, 11, 12)
A regioisomer mixture consisting of Exemplified Compounds CT-10, 11, 12 was prepared according to Scheme 2 below. Detailed conditions are described below.

  Compound E5 g which is a tetraphenylbenzidine derivative was charged in 50 ml of DMF and heated to 60 ° C. After the temperature increase, 4.3 g of phosphorus oxychloride was added dropwise at 70 ° C. or less, and the reaction was performed in the range of 60 ° C. to 70 ° C. for 4 hours after the completion of the addition. After completion of the reaction, the temperature was lowered to room temperature, and the reaction solution was discharged into a mixed solution of 100 ml of water / 100 ml of toluene for hydrolysis. After hydrolysis, the organic layer was separated, the organic layer was washed with an aqueous sodium hydroxide solution and water until the organic layer became neutral, and the organic layer was concentrated. The concentrated residue was purified by silica gel chromatography to obtain 4.7 g of Compound F which is a tetraphenylbenzidine derivative having a formyl group. (Yield 85.2%)

In 100 ml of THF, 4.5 g of a regioisomer mixture (compound C: compound D = 73: 27) composed of 4.5 g of the above formyl compound F and the compound C and the compound D which are phosphoric acid ester derivatives were dissolved and dissolved. After dissolution, 2.0 g of potassium t-butoxy was added and stirred at room temperature for 30 minutes for reaction. After completion of the reaction, the reaction solution is discharged into water, extracted with toluene, the organic layer is concentrated, and the concentrated residue is purified by silica gel chromatography to comprise the charge transport material CT-10, 11, 12 as the target substance. 4.4 g of a mixture of regioisomers was obtained. (Yield 70.2%) The composition ratio of the obtained positional isomer mixture consisting of CT-10, 11, 12 was determined by measuring 1H-NMR (nuclear magnetic resonance). (Composition ratio: CT-10: CT-11: CT-12 = 54: 39: 7)
(Production Example 3: Regioisomer mixture consisting of Exemplified Compounds CT-13, 14, 15)
A regioisomer mixture comprising Exemplified compounds CT-13, 14, 15 was prepared according to Scheme 2 below. Detailed conditions are described below.

Compound G (10 g), which is a tetraphenylbenzidine derivative, was charged in 130 ml of DMF and heated to 60 ° C. After the temperature rise, 20.7 g of phosphorus oxychloride was added dropwise at 75 ° C. or lower, and the reaction was carried out in the range of 70 ° C. to 75 ° C. for 12 hours after the completion of the addition. After completion of the reaction, the temperature was lowered to room temperature, and the reaction solution was discharged into a mixed solution of 250 ml of water / 250 ml of toluene for hydrolysis. After hydrolysis, the organic layer was separated, the organic layer was washed with an aqueous sodium hydroxide solution and water until the organic layer became neutral, and the organic layer was concentrated. The concentrated residue was purified by silica gel chromatography to obtain 8.5 g of Compound H, which is a tetraphenylbenzidine derivative having a formyl group. (Yield 77.0%)
In 100 ml of THF, 4.5 g of a regioisomer mixture (compound C: compound D = 71: 29) composed of 4.5 g of the above formyl compound H and the compound C and compound D which are phosphate ester derivatives was charged and dissolved. After dissolution, 2.0 g of potassium t-butoxy was added and stirred at room temperature for 30 minutes for reaction. After completion of the reaction, the reaction solution is discharged into water, extracted with toluene, the organic layer is concentrated, and the concentrated residue is purified by silica gel chromatography to comprise the charge transport material CT-13, 14, 15 as the target substance. 5.5 g of a regioisomer mixture was obtained. (Yield 87.7%) The composition ratio of the obtained positional isomer mixture consisting of CT-13, 14, 15 was determined by measuring 1H-NMR (nuclear magnetic resonance). (Composition ratio: CT-13: CT-14: CT-15 = 51: 41: 8)
(Examples 1-6, Comparative Examples 1-11: Evaluation of an electrophotographic photoreceptor)
<Method for creating electrophotographic photoreceptor>
Using the conductive support on which an aluminum vapor deposition film (thickness 70 nm) is formed on the surface of a biaxially stretched polyethylene terephthalate resin film (thickness 75 μm), the following undercoat layer dispersion is applied on the vapor deposition layer of the support: The coating was applied by a bar coater so that the film thickness after drying was 1.25 μm or less, and dried to form an undercoat layer.

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

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

A charge generating layer coating liquid was prepared by mixing the above-described atomization treatment liquid obtained by the atomization dispersion treatment, the above-described binder liquid, and 230 parts by weight of 1,2-dimethoxyethane. This charge generation layer coating solution is applied onto the undercoat layer on the conductive support by a bar coater so that the film thickness after drying is 0.4 μm and dried to form a charge generation layer. did.
(Formation of charge transport layer)
As the binder resin, 51 mol% of a repeating unit (unit represented by the following formula (PA)) having 2,2-bis (4-hydroxy-3-methylphenyl) propane shown below as an aromatic diol component, 1 , 1-bis (4-hydroxyphenyl) -1-phenylethane as an aromatic diol component and a repeating unit (unit represented by the following formula (PB)) of 49 mol%, derived from pt-butylphenol A polycarbonate resin having a terminal structure (Mv = 30,500) was used. Then, 50 parts by weight of the charge transport material, 100 parts by weight of the binder resin, 8 parts of the antioxidant having the structure of the following formula (AOX1), and 0.03 part by weight of silicone oil as the leveling agent were added to tetrahydrofuran / toluene (weight ratio 8). / 2) A charge transport layer coating solution was prepared by dissolving in 640 parts by weight of a mixed solvent.

The obtained coating solution for charge transport layer was applied onto the above-described charge generation layer so that the film thickness after drying was 25 μm to obtain an electrophotographic photosensitive member having a laminated photosensitive layer.
The electrophotographic photosensitive member (photosensitive member number: photosensitive member A to C, photosensitive member RA to RG) having a laminated type photosensitive layer was produced by the above-described steps. Since the charge transport material was not completely dissolved in the layer coating solution preparation stage, the photoreceptor could not be produced. The breakdown of each electrophotographic photosensitive member is as follows.
Photoreceptor A (Example 1: Regioisomer mixture comprising the following structural formulas (CT-7) to (CT-9) is used as a charge transport material)

[Composition ratio of regioisomer mixture:
CT-7: CT-8: CT-9 = 47: 43: 10]
Photoreceptor B (Example 2: A regioisomer mixture comprising the following structural formulas (CT-10) to (CT-12) is used as a charge transport material)

[Composition ratio of regioisomer mixture:
CT-10: CT-11: CT-12 = 54: 39: 7]
Photoreceptor C (Example 1: Regioisomer mixture comprising the following structural formulas (CT-13) to (CT-15) is used as a charge transport material)

[Composition ratio of regioisomer mixture:
CT-13: CT-14: CT-15 = 51: 41: 8]
Photoreceptor RA (Comparative Example 1: Use of a charge transport material of the following structural formula (D))

[Synthesis Based on Example 1 of JP-A-2006-8670]
Photoreceptor RB (Comparative Example 2: Use of a charge transport material of the following structural formula (E))

[Synthesis Based on Production Example 1 of JP-A-7-36203]
Photoreceptor RC (Comparative Example 3: Use of a charge transport material of the following structural formula (F))

[Synthesis Based on Example 1 of JP-A-2002-80432]
Photoreceptor RD (Comparative Example 4: Use of a charge transport material of the following structural formula (G))

[Synthesis Based on Synthesis Example 4 of JP 2008-83105 A]
Photoreceptor RE (Comparative Example 5: Use of a charge transport material of the following structural formula (H))

  Photoreceptor RF (Comparative Example 6: Use of charge transport material of structural formula (I) below)

  Photoreceptor RG (Comparative Example 7: Use of a charge transport material of the following structural formula (J))

<Evaluation of electrophotographic photoreceptor>
The electrophotographic photosensitive members of Examples 1 to 3 and Comparative Examples 1 to 4 were produced in accordance with electrophotographic standard standards ("Basic and Application of Secondary Electrophotographic Technology", edited by Electrophotographic Society, Corona) , 404-405), and the electrical characteristics were evaluated by carrying out a cycle of charging, exposure, potential measurement, and static elimination according to the following procedure.

Under the conditions of a temperature of 25 ° C. and a humidity of 50%, the photosensitive member is charged so that the initial surface potential becomes −700 V, and the halogen lamp light is irradiated with a monochromatic light of 780 nm by an interference filter. The irradiation energy (half exposure energy) at −350 V was measured as sensitivity (unit: μJ / cm ² ). The photosensitive member was charged so that the initial surface potential was −700 V, and the surface potential (unit: −V) measured after exposure with an irradiation energy of 0.6 μJ / cm ^{2 was} defined as the residual potential. And after making initial surface potential into -700V, the surface potential after leaving it to stand for 5 seconds in a dark place was measured, and the difference was made into dark attenuation (unit: V).
The measurement results are shown in Table-1.

以上の結果から、本発明範囲内である電荷輸送物質は電荷輸送層用の塗布溶媒に対する溶解性が非常に高く、成膜性良好で、本発明範囲内である電荷輸送物質を用いた場合に、高感度であり、暗減衰も少なく帯電性も良好で、かつ低い残留電位を示す高機能な感光体を提供することが可能であることが分かる。

From the above results, the charge transport material within the scope of the present invention has very high solubility in the coating solvent for the charge transport layer, has good film formability, and the charge transport material within the scope of the present invention is used. It can be seen that it is possible to provide a highly functional photoreceptor that has high sensitivity, low dark decay, good chargeability, and low residual potential.

Photoconductor D (Example 4)
By performing the same operation as in Example 1 except that the binder resin of the coating solution for the charge transport layer in <Electrophotographic photosensitive member production method> is changed to a polyarylate resin having the following structural formula (PC): Photoconductor D was produced.

Photoconductor E (Example 5)
By performing the same operation as in Example 2 except that the binder resin of the coating solution for the charge transport layer in <Electrophotographic photosensitive member production method> is changed to a polyarylate resin having the structural formula (PC). Photoconductor E was produced.
Photoconductor F (Example 6)
By performing the same operation as in Example 3 except that the binder resin of the coating solution for the charge transport layer in <Electrophotographic photosensitive member production method> is changed to a polyarylate resin having the structural formula (PC). Photoconductor F was produced.

Comparative photoreceptor RH (Comparative Example 8)
By performing the same operation as in Comparative Example 1 except that the binder resin of the coating solution for the charge transport layer in <Electrophotographic photosensitive member production method> is changed to the polyarylate resin having the structural formula (PC). Photoconductor RH was manufactured.
Comparative photoreceptor RI (Comparative Example 9)
By performing the same operation as in Comparative Example 2 except that the binder resin of the coating solution for the charge transport layer in <Electrophotographic photosensitive member production method> is changed to a polyarylate resin having the structural formula (PC). A photoreceptor RI was manufactured.

Comparative photoconductor RJ (Comparative Example 10)
By performing the same operation as in Comparative Example 3 except that the binder resin of the coating solution for the charge transport layer in the <Electrophotographic photoreceptor preparation method> is changed to a polyarylate resin having the structural formula (PC), Photoconductor RJ was manufactured.
Comparative photoreceptor RK (Comparative Example 11)
By performing the same operation as in Comparative Example 4 except that the binder resin of the coating solution for the charge transport layer in the <Electrophotographic photoreceptor preparation method> is changed to the polyarylate resin having the structural formula (PC), Photoconductor RK was manufactured.

  Table 2 shows the results of evaluation of the electrophotographic photoreceptors of Examples 4 to 6 and Comparative Examples 8 to 11 according to the above <Evaluation of electrophotographic photoreceptor>.

以上の結果から、本発明範囲内である電荷輸送物質を用いた場合に、電荷輸送層に用いるバインダー樹脂に依存することなく、高感度であり、暗減衰も少なく帯電性も良好、かつ低い残留電位を示す高機能な感光体を提供することが可能であることが明らかとなった。

From the above results, when using a charge transport material within the scope of the present invention, high sensitivity, low dark decay, good chargeability, and low residual without depending on the binder resin used in the charge transport layer It has been found that it is possible to provide a high-performance photoconductor showing potential.

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

Claims (5)

An electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, wherein the photosensitive layer contains a compound represented by the following formula (1).

(In formula (1), R ^{1 to} R ² each independently represents an alkyl group, and R ^{3 to} R ⁹ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group. Represents an integer of 1 to 5, and l and m each independently represents an integer of 1 to 5.   In an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, the photosensitive layer contains a compound represented by formula (1), and the compound represented by formula (1) is a regioisomer mixture. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is provided.   In an electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, in the powder X-ray diffraction spectrum by the compound represented by the formula (1) in the photosensitive layer and CuKα characteristic X-ray, Bragg angle (2θ 3. The electrophotographic photosensitive member according to claim 1, comprising a crystalline oxytitanium phthalocyanine having a diffraction peak at ± 0.2 ° of at least 24.1 ° and 27.2 °.   The electrophotographic photosensitive member according to any one of claims 1 to 3, a charging device that charges the electrophotographic photosensitive member, an exposure device that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image, And an electrophotographic photosensitive member cartridge comprising: at least one selected from the group consisting of developing devices for developing an electrostatic latent image formed on the electrophotographic photosensitive member.   The electrophotographic photosensitive member according to claim 1, a charging device that charges the electrophotographic photosensitive member, an exposure device that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image, and An image forming apparatus comprising: a developing device that develops an electrostatic latent image formed on the electrophotographic photosensitive member.

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