JP2006251073A - Electrophotographic photoreceptor and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which has satisfactory electrical characteristics in various environments and in which mechanical durability and electrical durability are made compatible with each other. <P>SOLUTION: The charge transport layer of the electrophotographic photoreceptor is comprised of two layers containing the enamine compound expressed by General Formula (1). The elastic power<SB>ηHU</SB>when the indentation maximum load 5 mN is loaded for 5 seconds in the environment of temperature 25°C of the surface side charge transport layer provided on the surface side facing outward and relative humidity 50% is ≥47.0% and the elastic power<SB>ηHU</SB>of the charge generating layer side charge transport layer provided on the charge generating layer side is ≤46.0%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photoreceptor used for electrophotographic image formation and an image forming apparatus including the same.

  In an electrophotographic image forming apparatus (hereinafter also referred to as an electrophotographic apparatus) that is frequently used as a copying machine, a printer, a facsimile machine, and the like, an image is formed through the following electrophotographic process. First, a photosensitive layer of an electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) provided in the apparatus is uniformly charged to a predetermined potential by a charger, and laser light or the like is irradiated from an exposure unit according to image information. To form an electrostatic latent image. The developer is supplied from the developing means to the formed electrostatic latent image, and the electrostatic latent image is developed by attaching colored fine particles called toner, which is a component of the developer, to the surface of the photoreceptor. It is visualized as a toner image. The formed toner image is transferred from the surface of the photoreceptor to a transfer material such as recording paper by a transfer unit, and fixed by a fixing unit.

  During the transfer operation by the transfer means, not all the toner on the surface of the photoconductor is transferred to the recording paper and transferred, but a part of the toner remains on the surface of the photoconductor. Further, the paper dust of the recording paper that comes into contact with the photoconductor during transfer may remain attached to the surface of the photoconductor. Such foreign matters such as residual toner and adhered paper dust on the surface of the photosensitive member adversely affect the quality of the formed image, and are therefore removed by a cleaning device (hereinafter also referred to as a cleaner) which is a cleaning means. Further, in recent years, cleanerless technology has advanced, and a so-called developing and cleaning system that collects residual toner by a cleaning function added to the developing unit is removed without providing an independent cleaning unit. After cleaning the surface of the photoreceptor in this manner, the surface of the photosensitive layer is neutralized by a static eliminator or the like, and the electrostatic latent image disappears.

  An electrophotographic photoreceptor used in such an electrophotographic process is configured by laminating a photosensitive layer containing a photoconductive material on a conductive substrate made of a conductive material. Conventionally, an electrophotographic photoreceptor using an inorganic photoconductive material (hereinafter referred to as an inorganic photoreceptor) has been used as the electrophotographic photoreceptor. As a typical inorganic photoreceptor, a selenium photoreceptor using a layer made of amorphous selenium (a-Se) or amorphous selenium arsenide (a-AsSe) as a photosensitive layer, zinc oxide (chemical formula: ZnO) Alternatively, a layer made of zinc oxide-based or cadmium sulfide-based photoconductor using cadmium sulfide (chemical formula: CdS) dispersed in a resin together with a sensitizer such as a dye as a photosensitive layer, and a layer made of amorphous silicon (a-Si) There is an amorphous silicon photoconductor (hereinafter referred to as a-Si photoconductor) used for the photosensitive layer.

  However, the inorganic photoreceptor has the following problems. For example, selenium photoreceptors and cadmium sulfide photoreceptors have problems with heat resistance and storage stability. Since selenium and cadmium are toxic to the human body and the environment, photoreceptors using these must be recovered after use and disposed of properly. Also, zinc oxide photoconductors have the disadvantages of low sensitivity and low durability, and are rarely used at present. In addition, an a-Si photosensitive member which is attracting attention as a non-polluting inorganic photosensitive member has advantages such as high sensitivity and high durability, but is manufactured using a plasma chemical vapor deposition method. It is difficult to form a uniform film, and image defects are likely to occur. In addition, the a-Si photosensitive member has disadvantages that productivity is low and manufacturing cost is high.

  As described above, since there are many problems with inorganic photoreceptors, development of photoconductive materials used in electrophotographic photoreceptors has progressed, and instead of the conventionally used inorganic photoconductive materials, Organic photoconductive materials, that is, organic photoconductors (abbreviated as OPC), are widely used. An electrophotographic photoreceptor using an organic photoconductive material (hereinafter referred to as an organic photoreceptor) has some problems in sensitivity, durability, and environmental stability, but is toxic, manufacturing cost and material design. In terms of the degree of freedom, there are many advantages over inorganic photoreceptors. The organic photoreceptor also has an advantage that the photosensitive layer can be formed by an easy and inexpensive method typified by a dip coating method. Because of these many advantages, organic photoreceptors are gradually becoming the mainstream of electrophotographic photoreceptors. Also, due to recent research and development, the sensitivity and durability of organic photoreceptors have been improved, and at present, organic photoreceptors have been used as electrophotographic photoreceptors except in special cases. Yes.

  In particular, the performance of organic photoreceptors has been remarkably improved by the development of function-separated photoreceptors in which a charge generation function and a charge transport function are assigned to different substances. In addition to the above-mentioned advantages of the organic photoconductor, the function-separated type photoconductor has an advantage that a photoconductor having an arbitrary characteristic can be relatively easily manufactured with a wide selection range of materials constituting the photosensitive layer. ing. As the function separation type photoreceptor, a stacked function separation type photoreceptor is frequently used. In the laminated type function separation type photoreceptor, a laminated type photosensitive member comprising a charge generation layer containing a charge generation material responsible for a charge generation function and a charge transport layer containing a charge transport material responsible for a charge transport function. A layer is provided. The charge generation layer and the charge transport layer are each formed in a form in which a charge generation material or a charge transport material is dispersed in a binder resin as a binder.

  Various materials such as phthalocyanine pigments, squarylium dyes, azo pigments, perylene pigments, polycyclic quinone pigments, cyanine dyes, squaric acid dyes, and pyrylium salt dyes are considered as charge generating materials used in functionally separated photoconductors. Various materials having high light resistance and high charge generation capability have been proposed.

  Examples of charge transport materials that have been developed include pyrazoline compounds, hydrazone compounds, triphenylamine compounds, stilbene compounds, pyrene derivatives having a condensed polycyclic hydrocarbon as a central mother nucleus, naphthalene derivatives, or terphenyl derivatives. .

Charge transport materials include
(1) being stable to light and heat;
(2) being stable against active substances such as ozone, nitrogen oxides (chemical formula: NOx) and nitric acid generated by corona discharge when charging the photoreceptor;
(3) having a high charge transport capability;
(4) High compatibility with organic solvent and binder resin,
(5) It must be easy and inexpensive to manufacture. However, the aforementioned known charge transport materials satisfy some of these requirements, but not all at a high level.

  In recent years, in response to the demands for miniaturization and speedup of electrophotographic apparatuses such as digital copying machines and printers, higher sensitivity is required as a photoreceptor characteristic, and charge transport materials have particularly high charge transport. Ability is required. In a high-speed electrophotographic process, since the time from exposure to development is short, a photoconductor excellent in photoresponsiveness is required. If the photoresponsiveness of the photoconductor is low, that is, if the surface potential decay rate after exposure is slow, the residual potential will rise and the surface potential will not be sufficiently attenuated, so it will be used repeatedly. As a result, the surface charge of the portion to be erased is not sufficiently erased by the exposure, and the image quality deteriorates at an early stage. In the function-separated type photoconductor, the charge generated in the charge generation material by light absorption is transported to the surface of the photosensitive layer by the charge transport material, so that the surface charge of the photoirradiated portion of the photoconductor is erased. The photoresponsiveness depends on the charge transport ability of the charge transport material. Therefore, in order to realize a photoreceptor having sufficient photoresponsiveness, the charge transport material is required to have a particularly high charge transport capability.

  As a charge transport material satisfying such requirements, an enamine compound having a charge transport capability higher than that of the aforementioned known charge transport material has been proposed (for example, see Patent Documents 1 to 4).

  Further, in the electrophotographic apparatus, the above-described charging, exposure, development, transfer, cleaning, and static elimination operations are repeatedly performed on the photosensitive member, so that the photosensitive member has high sensitivity and optical response. In addition to excellent properties, it is required to have excellent electrical and mechanical durability. Specifically, the surface layer of the photoconductor is not easily worn by rubbing with a cleaning member, etc., and has excellent printing durability, and electrical characteristics do not deteriorate even when used repeatedly in harsh environments such as high-temperature and high-humidity environments. Is required. Further, the photoreceptor is required to have a small environmental characteristic change and excellent environmental stability so that a high-quality image can be provided regardless of the use environment. In particular, in order to realize maintenance-free electrophotographic apparatus, the photosensitive member has sufficient electrical and mechanical durability and environmental stability, and can operate stably for a long time in various environments. Is required.

  As a method for improving the mechanical durability of the photoconductor, the ratio of the binder resin in the surface layer is increased in order to improve the printing durability of the surface layer, and the resin having a large molecular weight as the binder resin in the surface layer. It has been proposed to use. However, increasing the ratio of the binder resin causes a decrease in the sensitivity of the photoreceptor, and is not suitable for increasing the speed. In addition, using a resin having a large molecular weight causes a high viscosity of the coating solution, leading to a decrease in productivity.

  Further, the printing durability of the surface layer of the photoreceptor is greatly related to the physical properties of the surface layer as well as the type and ratio of the binder resin constituting the surface layer. Not only the physical properties of the surface of the photoreceptor but also one of the indices for evaluating the physical properties of materials, particularly the mechanical properties, is hardness. Hardness is defined as the stress from the material against the indentation of the indenter. Attempts have been made to quantify the mechanical properties of the film constituting the surface of the photoreceptor by using this hardness as a physical parameter for knowing the physical properties of the material. As a test method for measuring hardness, for example, a scratch strength test, a pencil hardness test, a Vickers hardness test, and the like are widely known.

  However, in these hardness tests, there is a problem in measuring the mechanical properties of materials that exhibit complex behavior in which plasticity and elasticity (including retardation components) are combined, such as a film composed of organic matter. . For example, in the Vickers hardness test, the hardness is evaluated by measuring the length of the indentation on the film. However, the hardness value obtained in this way reflects only the plasticity of the film. However, it is not possible to accurately evaluate the mechanical properties of a deformation form including a large proportion of elastic deformation. That is, the mechanical properties of a film composed of organic materials must be evaluated in consideration of various properties.

In the electrophotographic photosensitive member in which the organic photosensitive layer constitutes the surface layer, as a physical property value serving as an index for judging the mechanical durability of the organic photosensitive layer, for example, plastic work rate (plastic deformation rate, η _plast ,%), An elastic power (elastic deformation rate, η _HU ,%) and the like have been proposed (see, for example, Patent Documents 5 and 6). The plastic work rate is a percentage of the plastic deformation work with respect to the sum of the plastic deformation work, which is energy required for plastic deformation, and the elastic work, which is energy required for elastic deformation. The elastic work rate is a percentage of the elastic deformation work with respect to the sum of the plastic deformation work and the elastic work. Therefore, the sum of the plastic power and the elastic power is 100 (%).

More specifically, Patent Document 5 sets the plastic work rate (plastic deformation rate) to 30 to 70%, and sets the universal hardness value (Hu) by the universal hardness test specified in DIN 50359-1 to 230. it is proposed to set the ~700N / mm ^2. Patent Document 5 describes that the mechanical deterioration of the surface layer of the photoreceptor is prevented by setting the numerical value in such a range. However, the numerical range of 30 to 70% of the plastic work rate is a range including almost all of the organic photosensitive layer containing a binder resin that is generally used at present. Therefore, even if the plastic work rate is within the above range, an organic photosensitive layer having sufficient mechanical durability is not always obtained.

Further, Patent Document 6 has an organic photosensitive layer and a protective layer containing a curable resin as a binder resin on a conductive support, and an elastic power η _HU (= [elastic work _// An electrophotographic photosensitive member having a plastic work amount + elastic work amount)] × 100) of 32 to 60% is proposed. However, the numerical value of elastic power of 32 to 60% is synonymous with plastic power of 40 to 68%, and as in Patent Document 5, an electrophotographic photoreceptor having an organic photosensitive layer formed as a surface layer, which is currently used. Is a range including almost all of the above. Furthermore, curable resins used as binder resins are also common in the technical field of electrophotographic photoreceptors. Therefore, Patent Document 6 does not substantially describe a solution means for obtaining an organic photosensitive layer having sufficient mechanical durability that can realize a photoreceptor excellent in long-term operational stability. Furthermore, the electrophotographic photosensitive member of Patent Document 6 has a problem that the formation of a protective layer containing a curable resin increases the cost.

Further, in the techniques disclosed in Patent Documents 5 and 6, in order to improve the printing durability of the surface layer of the photoreceptor, the elastic power η _HU , the plastic power η _{plas and the} like of the surface layer are controlled within a predetermined range. However, depending on the value of the elastic power, etc., there is a problem that the residual potential increases due to repeated use in a high temperature and high humidity environment, and the sensitivity decreases. This increase in residual potential and the resulting decrease in sensitivity cannot be suppressed even when the enamine compounds disclosed in Patent Documents 1 to 4 described above are used as charge transport materials. Further, depending on the type of the charge transport material, the photoresponsiveness may be lowered in a low temperature and low humidity environment, and sufficient photoresponsiveness may not be obtained. Patent Documents 5 and 6 do not describe means for suppressing an increase in residual potential under such a high-temperature and high-humidity environment and a decrease in photoresponsiveness under a low-temperature and low-humidity environment. Below, a photoconductor that has excellent electrical characteristics such as photoresponsiveness and has both mechanical durability and electrical durability has not been realized.

Japanese Patent Laid-Open No. 2-51162 Japanese Patent Laid-Open No. 6-43674 Japanese Patent Laid-Open No. 10-69107 JP-A-7-134430 JP 2000-10320 A JP 2002-6526 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member having good electrical characteristics and having both mechanical durability and electrical durability in various environments, and an image forming apparatus including the same. is there.

The present invention is an electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate,
The charge transport layer includes two layers of a charge generation layer side charge transport layer provided on the charge generation layer side and a surface side charge transport layer provided on the surface side facing outward,
The surface-side charge transport layer is
In an environment where the temperature is 25 ° C. and the relative humidity is 50%, the elastic work rate η _HU is 57.0% or more when the maximum indentation load of 5 mN is applied to the surface for 5 seconds, and is expressed by the following general formula (1). Containing enamine compounds
The charge generation layer side charge transport layer is
The electrophotographic photosensitive member is characterized in that the elastic work modulus η _HU is 46.0% or less and an enamine compound represented by the following general formula (1) is contained.

(In the formula, Ar ¹ and Ar ² each represent an aryl group or a heterocyclic group which may have a substituent. Ar ³ represents an aryl group, a heterocyclic group or an aralkyl which may have a substituent. Each of Ar ⁴ and Ar ⁵ represents an aryl group, a heterocyclic group, an aralkyl group or an alkyl group, which may have a hydrogen atom or a substituent, provided that Ar ⁴ and Ar ⁵ At least one of them is a group other than a hydrogen atom, and a carbon atom to which the group = CAr ⁴ Ar ⁵ is bonded is bonded to a divalent aromatic ring group or heterocyclic group instead of the group = CAr ⁴ Ar ⁵ R ¹ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent, and R ² , R ³ and R ⁴ may each have a hydrogen atom or a substituent. , Archi Group, .n of an aryl group, a heterocyclic group or aralkyl group is an integer of 0 to 3. However, when n is 0, Ar ³ is a heterocyclic group which may have a substituent. The A plurality of R ² and R ³ may be the same or different when n is 2 or 3. R ⁵ is a hydrogen atom, a halogen atom or an alkyl group which may have a substituent, Represents an alkoxy group, a dialkylamino group or an aryl group, wherein l represents an integer of 1 to 6. However, when l is 2 or more, a plurality of R ^{5 s} may be the same or different; A divalent fused ring group may be formed together with the naphthylene group to be bonded.)

  The present invention is characterized in that the enamine compound represented by the general formula (1) is an enamine compound represented by the following general formula (1a).

(In the formula, Ar ⁴ , Ar ⁵ , R ⁵ and l have the same definitions as in general formula (1). M represents 1 or 2. R ⁶ , R ⁷ and R ⁸ are each a hydrogen atom, a halogen atom, or a halogen atom. An alkyl group, an alkoxy group, a dialkylamino group or an aryl group, which may have an atom or a substituent, represents i, j and k each represent an integer of 1 to 5, provided that i, j or k is 2 In the above, a plurality of corresponding R ⁶ , R ⁷ or R ⁸ may be the same or different, and may form a monovalent fused ring group together with the phenyl group to which they are bonded. .)

  In the present invention, the enamine compound represented by the general formula (1a) is an enamine compound represented by the following general formula (1b).

(In the formula, m has the same definition as in general formula (1a). R ^8a represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.)

The present invention also provides the electrophotographic photoreceptor of the present invention,
Charging means for charging the electrophotographic photosensitive member;
Exposure means for exposing a charged electrophotographic photosensitive member;
Developing means for developing an electrostatic latent image formed by exposure;
A transfer means for transferring a toner image formed on the surface of the electrophotographic photosensitive member by development to the transfer material from the surface;
An image forming apparatus comprising: a cleaning unit that cleans the surface of the electrophotographic photosensitive member after the toner image is transferred.

According to the present invention, an electrophotographic photosensitive member is formed by sequentially laminating a charge generation layer and a charge transport layer on a conductive substrate, and the charge transport layer includes: a charge generation layer side charge transport layer provided on the charge generation layer side; And two layers including a surface side charge transport layer provided on the surface side facing outward. The surface-side charge transport layer contains an enamine compound represented by the general formula (1), and the elastic work when a maximum pressing force of 5 mN is applied to the surface for 5 seconds in an environment of a temperature of 25 ° C. and a relative humidity of 50%. The rate η _HU (hereinafter sometimes simply referred to as η _HU ) is set to 47.0% or more. The charge generation layer side charge transport layer contains an enamine compound represented by the general formula (1), and the elastic power η _HU is set to 46.0% or less. This realizes a charge transport layer having excellent printing durability. In addition, an increase in residual potential when used repeatedly in a severe environment such as a high temperature and high humidity environment can be suppressed, and a decrease in sensitivity can be prevented. Moreover, sufficient photoresponsiveness can be obtained even in a low temperature and low humidity environment. Therefore, it is possible to obtain an electrophotographic photosensitive member that has good electrical characteristics such as photoresponsiveness and has both mechanical durability and electrical durability in various environments.

  Moreover, according to this invention, the enamine compound represented by General formula (1a) is preferable among the enamine compounds represented by General formula (1), and the enamine compound represented by General formula (1b) is further more preferable. By using the enamine compound represented by the general formula (1a), particularly the enamine compound represented by the general formula (1b), it is possible to improve the photoresponsiveness and obtain an electrophotographic photosensitive member particularly excellent in environmental stability. it can.

  Further, according to the present invention, the image forming apparatus includes the electrophotographic photosensitive member of the present invention having favorable electrical characteristics and excellent in both mechanical durability and electrical durability under various environments. Provided. Therefore, an image forming apparatus that can stably provide a high-quality image free from scratches and uneven density in various environments over a long period of time, and is low in cost and low in maintenance frequency is realized.

  FIG. 1 is a partial cross-sectional view showing a simplified configuration of an electrophotographic photoreceptor 1 according to a first embodiment of the present invention. An electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor) 1 of the present embodiment is a cylindrical conductive substrate 11 made of a conductive material and a layer laminated on the outer peripheral surface of the conductive substrate 11. A charge generation layer 12 containing a charge generation material, and a charge transport layer 15 which is further laminated on the charge generation layer 12 and contains a charge transport material. The charge generation layer 12 and the charge transport layer 15 constitute a photosensitive layer 16. That is, the photoreceptor 1 is a multilayer photoreceptor.

  The charge transport layer 15 includes at least two layers. In the present embodiment, the charge transport layer 15 is further laminated on the charge generation layer side charge transport layer 13 provided in contact with the charge generation layer 12 on the charge generation layer 12 side, and the charge generation layer side charge transport layer 13. 2 layers including a surface side charge transport layer 14 provided on the surface side facing the outside of the charge transport layer 15.

  The conductive substrate 11 serves as an electrode of the photoreceptor 1 and also functions as a support member for the other layers 12, 13 and 14. The shape of the conductive substrate 11 is cylindrical in the present embodiment, but is not limited thereto, and may be a columnar shape, a sheet shape, an endless belt shape, or the like.

  As the conductive material constituting the conductive substrate 11, for example, a single metal such as aluminum, copper, zinc, or titanium, or an alloy such as an aluminum alloy or stainless steel can be used. Also, not limited to these metal materials, polymer materials such as polyethylene terephthalate, nylon or polystyrene, those obtained by laminating metal foil on the surface of hard paper or glass, those obtained by vapor deposition of metal materials, or conductivity A material obtained by depositing or coating a layer of a conductive compound such as a polymer, tin oxide, or indium oxide can also be used. These conductive materials are used after being processed into a predetermined shape.

  If necessary, the surface of the conductive substrate 11 is irregularly reflected within a range that does not affect the image quality, such as anodic oxide film treatment, surface treatment with chemicals or hot water, coloring treatment, or roughening the surface. Processing may be performed. In an electrophotographic process using a laser as an exposure light source, the wavelengths of the laser light are uniform, so the laser light reflected on the surface of the photoconductor and the laser light reflected inside the photoconductor cause interference, and the interference due to this interference occurs. Stripes may appear on the image and cause image defects. By performing the above-described treatment on the surface of the conductive substrate 11, image defects due to interference of laser light having the same wavelength can be prevented.

  The charge generation layer 12 contains, as a main component, a charge generation material that generates charges by absorbing light. Substances effective as charge generation materials include azo pigments such as monoazo pigments, bisazo pigments and trisazo pigments, indigo pigments such as indigo and thioindigo, perylene pigments such as peryleneimide and perylene anhydride, anthraquinone and Polycyclic quinone pigments such as pyrenequinone, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, organic photoconductive materials such as squarylium dyes, pyrylium salts and thiopyrylium salts, triphenylmethane dyes, and selenium and amorphous silicon And inorganic photoconductive materials. One of these charge generation materials may be used alone, or two or more thereof may be used in combination.

  Among the above-described charge generating materials, phthalocyanine pigments are preferable, and oxotitanium phthalocyanine compounds represented by the following general formula (2) are particularly preferable.

In the general formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ each represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. r, s, y and z each represent an integer of 1 to 4. Examples of the halogen atom represented by R ²¹ , R ²² , R ²³ and R ²⁴ include a fluorine atom, a chlorine atom and a bromine atom. Among these, a fluorine atom and a chlorine atom are preferable. Examples of the alkyl group include linear alkyl groups such as methyl group, ethyl group, n-propyl group, and n-butyl group, and branched alkyl groups such as isopropyl group and t-butyl group. An alkyl group having 1 to 4 carbon atoms is preferred. Examples of the alkoxy group include linear alkoxy groups such as methoxy group, ethoxy group, and n-propoxy group, and branched alkoxy groups such as isopropoxy group. Among these, alkoxy groups having 1 to 4 carbon atoms are included. Is preferred.

  The oxotitanium phthalocyanine compound represented by the general formula (2) has higher charge generation efficiency and higher charge injection efficiency than other charge generation materials, and generates a large amount of charge by absorbing light. The generated charge is efficiently injected into the charge transport material contained in the charge transport layer 13 without accumulating the generated charge therein. In the present embodiment, as will be described later, the charge transport material contained in the charge generation layer side charge transport layer 13 is an enamine compound represented by the general formula (1) having excellent charge transfer capability. Therefore, the charge generated in the oxotitanium phthalocyanine compound represented by the general formula (2) which is a charge generating substance by light absorption is efficiently transferred to the enamine compound represented by the general formula (1) which is a charge transporting substance. It is injected and smoothly transported to the surface-side charge transport layer 14 surface which is the surface of the photosensitive layer 16. Therefore, by using the oxotitanium phthalocyanine compound represented by the general formula (2) as the charge generation material and the enamine compound represented by the general formula (1) described later as the charge transport material, the sensitivity and sensitivity of the photoreceptor 1 can be improved. The resolution can be improved.

  Among the oxotitanium phthalocyanine compounds represented by the general formula (2), particularly preferred are at least a Bragg angle 2θ (error: 2θ) in an X-ray diffraction spectrum for Cu-Kα characteristic X-ray (wavelength: 1.54Å). And those having a crystal structure showing a diffraction peak at 27.2 °. Here, the Bragg angle 2θ is an angle formed by incident X-rays and diffracted X-rays, and represents a so-called diffraction angle.

The oxotitanium phthalocyanine compound represented by the general formula (2) is, for example, “Phthalocyanine compound” by Moser and Thomas.
The compound can be produced by a conventionally known production method such as the method described in “Compounds”). For example, in the oxotitanium phthalocyanine compound represented by the general formula (2), oxotitanium phthalocyanine in which R ²¹ , R ²² , R ²³ and R ²⁴ are all hydrogen atoms, heats phthalonitrile and titanium tetrachloride. Dichlorotitanium phthalocyanine is synthesized by melting or reacting by heating in a suitable solvent such as α-chloronaphthalene, followed by hydrolysis with a base or water. Alternatively, oxotitanium phthalocyanine can also be produced by reacting isoindoline with titanium tetraalkoxide such as tetrabutoxytitanium in a suitable solvent such as N-methylpyrrolidone.

  Charge generation materials include triphenylmethane dyes represented by methyl violet, crystal violet, knight blue and Victoria blue, erythrosine, rhodamine B, rhodamine 3R, acridine dyes represented by acridine orange and frapeosin, methylene blue and methylene It may be used in combination with sensitizing dyes such as thiazine dyes typified by green, oxazine dyes typified by capri blue and meldra blue, cyanine dyes, styryl dyes, pyrylium salt dyes or thiopyrylium salt dyes. .

  The charge generation layer 12 may contain a binder resin in order to improve the binding property. Examples of the binder resin used for the charge generation layer 12 include polyester resin, polystyrene resin, polyurethane resin, phenol resin, alkyd resin, melamine resin, epoxy resin, silicone resin, acrylic resin, methacrylic resin, polycarbonate resin, polyarylate resin, Examples thereof include resins such as phenoxy resin, polyvinyl butyral resin, and polyvinyl formal resin, and copolymer resins containing two or more repeating units constituting these resins. Specific examples of the copolymer resin include insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin. be able to. The binder resin is not limited to these, and a resin generally used as the binder resin of the charge generation layer 12 can be used. One kind of these resins may be used alone, or two or more kinds thereof may be mixed and used.

  When the binder resin is contained in the charge generation layer 12, the charge generation material is preferably used in the range of 10 parts by weight to 99 parts by weight with respect to 100 parts by weight of the binder resin. If the amount of the charge generating material used is less than 10 parts by weight, the sensitivity of the photoreceptor 1 may be lowered. When the amount of the charge generation material used exceeds 99 parts by weight, the film strength of the charge generation layer 12 may be reduced. Further, the dispersibility of the charge generation material in the charge generation layer 12 is reduced, the coarse particles are increased, the surface charge other than the portion to be erased is reduced by exposure, and the toner is adhered to the image defect, particularly, the white background, and is minute. There is a risk that the fogging of an image called a black spot where black spots are formed increases.

  As a method for forming the charge generation layer 12, a vacuum deposition method in which the above-described charge generation material is vacuum-deposited on the surface of the conductive substrate 11, or a coating solution for the charge generation layer containing the above-described charge generation material is applied to the surface of the conductive substrate 11. The application method etc. which apply | coat to are mentioned, The application | coating method is used suitably among these. The coating solution for the charge generation layer can be prepared, for example, by adding the above-described charge generation material and, if necessary, the above-described binder resin in a suitable solvent and dispersing by a known method.

  Examples of the solvent used in the coating solution for the charge generation layer include halogenated hydrocarbons such as dichloromethane and dichloroethane, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, tetrahydrofuran, dioxane, and the like. Ethers, ethylene glycol alkyl ethers such as 1,2-dimethoxyethane, aromatic hydrocarbons such as benzene, toluene and xylene, aprotic polarities such as N, N-dimethylformamide and N, N-dimethylacetamide A solvent etc. are mentioned. Among these, non-halogen organic solvents are preferably used in consideration of the global environment. One of these solvents may be used alone, or two or more thereof may be mixed and used as a mixed solvent.

  The charge generation material may be pulverized in advance by a pulverizer before being dispersed in the solvent. Examples of the pulverizer used for the pulverization treatment include a ball mill, a sand mill, an attritor, a vibration mill, and an ultrasonic disperser. Examples of the disperser used when dispersing the charge generating substance in the solvent include a paint shaker, a ball mill, and a sand mill. As a dispersion condition at this time, an appropriate condition is selected so that impurities are not mixed due to wear of a container and a member constituting the disperser.

  Examples of the coating method for the charge generation layer coating liquid include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method. Among these coating methods, in particular, the dip coating method is a method of forming a layer on the surface of the substrate by immersing the substrate in a coating tank filled with a coating solution and then pulling it up at a constant speed or a sequentially changing speed. It is relatively simple and excellent in terms of productivity and cost, and is therefore preferably used. In order to stabilize the dispersibility of the coating liquid, the apparatus used for the dip coating method may be provided with a coating liquid dispersing apparatus represented by an ultrasonic generator. In consideration of productivity and the like, an optimum method is appropriately selected and used in accordance with various conditions such as physical properties of the coating solution.

  The layer thickness of the charge generation layer 12 is preferably 0.05 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 1 μm or less. If the layer thickness of the charge generation layer 12 is less than 0.05 μm, the light absorption efficiency is lowered, and the sensitivity of the photoreceptor 1 may be lowered. If the thickness of the charge generation layer 12 exceeds 5 μm, the charge transfer within the charge generation layer 12 becomes a rate-determining step in the process of erasing the charge on the surface of the photosensitive layer 16, and the sensitivity of the photoreceptor 1 may be reduced.

  The charge transport layer 15 provided on the charge generation layer 12 includes the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14 as described above. The charge generation layer side charge transport layer 13 and the surface side charge transport layer 14 each accept a charge generated by the charge generation material contained in the charge generation layer 12 and transport the same, and a charge transport material And a binder resin that binds.

The surface coating physical properties of the surface-side charge transport layer 14 provided on the surface side facing the outside of the charge transport layer 15 were subjected to an indentation maximum load of 5 mN for 5 seconds in an environment of a temperature of 25 ° C. and a relative humidity of 50%. In this case, the elastic power η _HU (hereinafter sometimes simply referred to as η _HU ) is set to be 47.0% or more. Further, the physical properties of the surface film of the charge generation layer side charge transport layer 13 provided on the charge generation layer 12 side are set so that the elastic power η _HU is 46.0% or less. Here, η _HU of the surface-side charge transport layer 14 is a value on the surface facing the outside of the surface-side charge transport layer 14, that is, the surface opposite to the side in contact with the charge generation layer-side charge transport layer 13. Η _HU of the generation layer side charge transport layer 13 is a value on the surface on the side in contact with the surface side charge transport layer 14.

Hereinafter, the elastic power η _HU will be described. In general, a solid material gradually develops a so-called creep phenomenon that gradually deforms with the passage of a load load holding time even when the load is relatively low. In particular, creep is prominent in organic polymer materials. Creep roughly includes a delayed elastic deformation component and a plastic deformation component, and is used as an index representing the viscoelasticity of a material.

When a load is applied to the solid material, only a part of the mechanical work W _total spent during indentation is used as the plastic deformation work W _plast , and the rest is the elastic recovery work (elasticity) when removing the load. The deformation work is released as W _elast . This elastic recovery work (elastic deformation work) W _elast includes an instantaneous elastic deformation component and a delayed elastic deformation component. The elastic power η _HU is a parameter that contributes particularly to elastic recovery among the viscoelasticity of the material.

The elastic power η _HU in the present embodiment is obtained as follows. FIG. 2 is a diagram illustrating a method for obtaining the elastic power η _HU of the material. The hysteresis line 3 shown in FIG. 2 starts the indentation load on the surface of the object to be measured and maintains the indentation process (A → B) from reaching the predetermined maximum indentation load Fmax (A → B) for a predetermined time t at the indentation maximum load Fmax. Demonstrates deformation (pushing depth change) history of unloading process (C → D) from load unloading process (B → C) until unloading is started and load reaches zero (0) to complete unloading .

Since the work W = ∫Fdh, the mechanical work W _total is calculated from the hysteresis line 3 shown in FIG. 2 and the indentation depth curve during the indentation process (A → B) and the indentation maximum load. It is represented by an area surrounded by a straight line connecting the point B reaching Fmax and the indentation depth h1 at the point B and the indentation depth axis. The elastic recovery work W _elast connects the indentation depth curve during load removal obtained in the unloading process (C → D) and the indentation depth h2 at point C and point C where unloading is started. It is represented by the area surrounded by the straight line and the indentation depth axis. The ratio of the work amount is the elastic work rate η _HU and is expressed by the equation (3).
η _HU = W _elast / W _total × 100 (%) (3)
_{However, W total = W elast + W} plast

As can be seen from the equation (3), the elastic work rate η _HU indicates that the larger the value, the larger the elastic recovery work (elastic deformation work) W _elast released at the time of load removal, and the easier the elastic recovery. .

In this embodiment, the elastic work rate η _HU is a square indenter diamond indenter (Vickers indenter) in an environment of a temperature of 25 ° C. and a relative humidity of 50%, and the indentation maximum load Fmax is 5 mN. It was measured under the condition that the load holding time t of the maximum load Fmax was 5 seconds. Such an elastic power η _HU can be obtained by, for example, a Fischer scope H100V (manufactured by Fischer Instrument Co., Ltd.).

The reason for limiting the elastic work η _HU of the layers 13 and 14 of the charge transport layer 15 will be described. First, the reason why the η _HU of the surface side charge transport layer 14 is set to 47.0% or more will be described. Since the surface-side charge transport layer 14 is composed of a mixture of a resin used as a binder resin and a low-molecular substance such as an enamine compound represented by the general formula (1), it cannot be a perfect plastic body, and some Contains an elastic component. From equation (3), it is considered that the smaller η _HU , the smaller the elastic recovery when external stress is applied, and the closer to the plastic body. If the η _{HU of the} surface-side charge transport layer 14 that is the surface layer of the photoreceptor 1 is less than 47.0%, the elastic recovery is small with respect to external stress, and the applied force tends to lead to surface deformation as it is. It becomes easy to cause outbreak. Furthermore, depending on the material of the member to which the load is applied, various problems occur even if the surface of the photoreceptor is less deformed. For example, the cleaning blade is likely to be reversed. Therefore, the elastic power η _HU of the surface-side charge transport layer 14 is set to 47.0% or more.

However, if the charge transport layer 15 is formed as a single layer and the elastic work coefficient η _HU of the charge transport layer is set to 47.0% or more like the surface side charge transport layer 14 according to the present embodiment, the high temperature and high humidity Repetitive use in the environment raises the problem that the residual potential increases and sensitivity decreases. This is considered to be because the matching between the charge generation layer 12 and the charge transport layer is poor, and the charge generated in the charge generation layer 12 is not smoothly injected into the charge transport material in the charge transport layer. Therefore, in this embodiment, the charge transport layer 15 is formed of two layers, that is, the surface side charge transport layer 14 and the charge generation layer side charge transport layer 13, and the η _HU of the surface side charge transport layer 14 is 47.0%. In addition to the above settings, the η _HU of the charge generation layer side charge transport layer 13 was set to 46.0% or less.

The fact that the η _HU of the charge generation layer side charge transport layer 13 is 46.0% or less is empirical, and when η _HU exceeds 46.0%, it becomes prominent by repeated use in a high temperature and high humidity environment. The increase in the residual potential was observed, and the increase in the residual potential was suppressed by setting it to 46.0% or less. Although there is no clear reason why the increase of the residual potential in a high temperature and high humidity environment can be suppressed by setting the η _HU of the charge generation layer side charge transport layer 13 to 46.0% or less, it is assumed as follows. The

As described above, it is considered that the smaller η _HU , the smaller the elastic recovery when external stress is applied, and the closer to the plastic body. In a charge transport layer having a small η _HU of 46.0% or less, a charge transport material having a low molecular weight, such as an enamine compound represented by the general formula (1) described later, as compared with a case where η _HU exceeds 46.0% Is considered to have entered the resin more uniformly and finely. For this reason, the charges generated in the charge generation layer 12 are more smoothly injected into the charge transport material and transported, and the interface between the charge generation layer 12 and the charge transport layer 15, that is, the charge generation layer 12 and the charge transport layer. Since it becomes difficult to be trapped at the interface with the generation layer side charge transport layer 13, it is considered that the increase in the residual potential is small even when used repeatedly over a long period of time in a harsh environment such as a high temperature and high humidity environment. On the other hand, when η _HU exceeds 46.0%, the matching between the charge generation layer 12 and the charge transport layer is poor, and the charge generated in the charge generation layer 12 is trapped at the interface with the charge transport layer. It is considered that the residual potential rises because it is not smoothly injected into the charge transport material in the charge transport layer.

The viscoelasticity of the surface side charge transport layer 14 set so that the elastic work rate η _HU is set to 47.0% or more is kept moderate. As a result, for example, when a load is applied to the surface of the surface-side charge transport layer 14 that is the surface of the photoreceptor 1, energy is dispersed so that the vertical force per unit area is reduced, and the energy is reduced by bounce. Therefore, the charge transport layer 15 having excellent printing durability is realized. Accordingly, even when the image forming operation of charging, exposure, development, transfer, cleaning and static elimination is repeated, the amount of film loss is reduced, the generation of scratches is suppressed, and the surface of the photoreceptor is smooth. Therefore, it is possible to prevent generation of scratches and uneven density on the formed image. In addition, by setting the elastic power η _HU of the charge generation layer side charge transport layer 13 to 46.0% or less, charging, exposure, development, transfer, cleaning in a severe environment such as high temperature and high humidity. Further, even when the image forming operation for static elimination is repeatedly executed over a long period of time, the residual potential does not increase and the sensitivity does not decrease, so that an image with a stable image density can be obtained.

As described above, the charge transport layer 15 is formed of two or more layers, and the η _HU of the surface-side charge transport layer 14 and the charge generation layer-side charge transport layer 13 is set in the above-described range. And a photoreceptor 1 having both electrical durability and electrical durability are realized. However, depending on the type of the charge transport material contained in each of the layers 13 and 14, sufficient photoresponsiveness may not be obtained in a low temperature and low humidity environment. Therefore, in this embodiment, an enamine compound represented by the general formula (1) to be described later is used as a charge transport material in order to realize a photoreceptor having good electrical characteristics such as photoresponsiveness even in a low temperature and low humidity environment. ing.

Adjustment of the elastic work η _HU of the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14 is carried out by adjusting the types and blending ratios of materials such as the charge transport material and binder resin contained in the layers 13 and 14, and the layers 13. , 14 can be performed by controlling the heat treatment conditions such as drying temperature and drying time.

  As the charge transport material contained in the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14, an enamine compound represented by the following general formula (1) is used.

In the general formula (1), Ar ¹ and Ar ² each represent an aryl group which may have a substituent or a heterocyclic group which may have a substituent. Examples of the aryl group include aryl groups having 1 to 4 rings such as a phenyl group, a naphthyl group, a biphenylyl group, a terphenyl group, an anthryl group, and a pyrenyl group. Among these, a phenyl group, a naphthyl group, and a biphenylyl group are exemplified. A 1 or 2 ring aryl group such as a group is preferred, and a phenyl group is particularly preferred.

  Examples of the substituent that these aryl groups may have include an alkyl group such as a methyl group, an ethyl group, and a propyl group (preferably an alkyl group having 1 to 4 carbon atoms), a trifluoromethyl group, a monofluoroethyl group, and the like. Alkalkyl groups (preferably haloalkyl groups having 1 to 5 carbon atoms), alkenyl groups such as 2-propenyl group and styryl group, alkoxy groups such as methoxy group, ethoxy group and propoxy group (preferably alkoxy having 1 to 4 carbon atoms) Group), monoalkylamino groups such as methylamino group and ethylamino group (preferably monoalkylamino groups having 1 to 4 carbon atoms), dialkylamino groups such as dimethylamino group, diethylamino group and diisopropylamino group (preferably carbon) Dialkylamino groups of 2 to 8), halogen atoms such as fluorine atom, chlorine atom and bromine atom , Heterocyclic groups such as thienyl groups (preferably 5-membered or 6-membered monocyclic heterocyclic groups containing at least one selected from oxygen atom, nitrogen atom and sulfur atom as hetero atoms), aryl such as phenoxy group Examples thereof include arylthio groups such as oxy group and phenylthio group. Among these, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a dialkylamino group having 2 to 8 carbon atoms are preferable.

  Examples of the aryl group having these substituents include a tolyl group, a methoxyphenyl group, a phenoxyphenyl group, a p- (phenylthio) phenyl group, and a p-styrylphenyl group. When the aryl group to which these substituents are bonded is a phenyl group, these substituents are preferably substituted at the para position of the phenyl group, such as a p-tolyl group and a p-methoxyphenyl group. . These substituents may form a monovalent fused ring group together with the aryl group to which they are bonded. Examples of the monovalent fused ring group include a 5,6,7,8-tetrahydro-1-naphthyl group.

Examples of the heterocyclic group represented by Ar ¹ and Ar ² include a furyl group, a thienyl group, a thiazolyl group, a benzofuryl group, a benzothiophenyl group, a benzothiazolyl group, a benzoxazolyl group, and a carbazolyl group. Monocyclic or condensed ring containing at least one selected from oxygen atom, nitrogen atom, sulfur atom, selenium atom and tellurium atom as a hetero atom, preferably at least one selected from oxygen atom, nitrogen atom and sulfur atom Heterocyclic groups are preferred. Here, the condensed cyclic heterocyclic group is a monovalent group generated from a condensed ring formed by condensation of monocyclic heterocyclic rings and a monovalent group generated from a condensed ring formed by condensation of an aromatic ring and a heterocyclic ring. That is.

  Examples of the substituent that these heterocyclic groups may have include the same substituents that the aryl group may have. Among these, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a C2-C8 dialkylamino group are preferable. Examples of the heterocyclic group having a substituent include N-methylindolyl group and N-ethylcarbazolyl group.

In the general formula (1), Ar ³ has an aryl group which may have a substituent, a heterocyclic group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Or a good alkyl group.

Specific examples of each group represented by Ar ³ include the following. Examples of the aryl group and heterocyclic group include the same aryl groups and heterocyclic groups represented by Ar ¹ and Ar ² . Examples of the substituent that each of these groups may have include the same substituents that the aryl group represented by Ar ¹ and Ar ² may have.

Examples of the aralkyl group include aralkyl groups having 1 to 3 carbon atoms in the alkyl moiety, such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, and a 1-naphthylethyl group. Among these, those in which the aryl moiety is a phenyl group are preferable, and a benzyl group is particularly preferable. Examples of the substituent that these aralkyl groups may have include the same substituents that the aryl group represented by Ar ¹ and Ar ² may have, and among them, those having 1 to 4 carbon atoms. An alkyl group, an alkoxy group having 1 to 4 carbon atoms, and a dialkylamino group having 2 to 8 carbon atoms are preferable. Examples of the aralkyl group having a substituent include a p-methoxybenzyl 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 a t-butyl group, a cyclohexyl group or a cyclopentyl group. Among these, an alkyl group having 1 to 6 carbon atoms is preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. Examples of the substituent that these alkyl groups may have include the same substituents that the aryl group represented by Ar ¹ and Ar ² may have, and among them, a halogen atom and a carbon number of 1 A 4-membered alkoxy group and a 5-membered or 6-membered monocyclic heterocyclic group containing at least one selected from an oxygen atom, a nitrogen atom and a sulfur atom as a hetero atom are preferred. Examples of the alkyl group having a substituent include a haloalkyl group such as a trifluoromethyl group and a fluoromethyl group, an alkoxyalkyl group such as a 1-methoxyethyl group, a thienylalkyl group such as a 2-thienylmethyl group and a 2-thienylethyl group. Etc.

In the general formula (1), Ar ⁴ and Ar ⁵ are each a hydrogen atom, an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or an aralkyl which may have a substituent. The alkyl group which may have a group or a substituent is shown. However, at least one of Ar ⁴ and Ar ⁵ is a group other than a hydrogen atom.

Examples of the aryl group and heterocyclic group represented by Ar ⁴ and Ar ⁵ include the same aryl groups and heterocyclic groups represented by Ar ¹ and Ar ² . In addition, examples of the aralkyl group and the alkyl group include the same aralkyl group and alkyl group represented by Ar ³ . Examples of the substituent that each of these groups may have include the same substituents that the aryl group represented by Ar ¹ and Ar ² may have.

In the general formula (1), a divalent aromatic ring group or a divalent heterocyclic group may be bonded to the carbon atom to which the group = CAr ⁴ Ar ⁵ is bonded instead of the group = CAr ⁴ Ar ^5. Good. Examples of the divalent aromatic ring group include 1-indanilidene group and 1,2,3,4-tetrahydro-1-naphthylidene group, bivalent condensed ring aromatic ring groups having 2 or 3 rings. It is done. Moreover, as a bivalent heterocyclic group, an oxygen atom, a nitrogen atom, a sulfur atom, a selenium atom, or a tellurium atom as a hetero atom such as a benzosberonylidene group or a 9-xanthenylidene group, preferably an oxygen atom, nitrogen And a bivalent fused cyclic heterocyclic group having 2 or 3 rings and containing at least one selected from an atom and a sulfur atom. The nitrogen atom contained in the divalent heterocyclic group may form an imino group together with a hydrogen atom, and may form an N-alkylimino group together with an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms). It may be. In addition, a divalent aromatic ring group and a heterocyclic group include an alkylene group such as a methylene group, an ethylene group and a methylmethylene group, an alkenylene group such as a vinylene group and a propenylene group, and an oxymethylene group (chemical formula: -O It may contain a divalent group such as a heteroalkylene group such as —CH ₂ —) and a heteroalkenylene group such as a thiovinylene group (chemical formula: —S—CH═CH—).

In the general formula (1), R ¹ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. Among these, a fluorine atom and a chlorine atom are preferable. The alkyl group, the same one as the alkyl group represented by Ar ^3. Examples of the substituent that these alkyl groups may have include the same substituents that the aryl group represented by Ar ¹ and Ar ² may have.

In the general formula (1), R ² , R ³ and R ⁴ may each have a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. The aralkyl group which may have a good heterocyclic group or a substituent is shown. Examples of the alkyl group and aralkyl group represented by R ² , R ³ and R ⁴ include the same alkyl group and aralkyl group represented by Ar ³ . Examples of the aryl group and heterocyclic group include the same aryl groups and heterocyclic groups represented by Ar ¹ and Ar ² . Examples of the substituent that each of these groups may have include the same substituents that the aryl group represented by Ar ¹ and Ar ² may have.

In General formula (1), n shows the integer of 0-3. However, when n is 0, Ar ³ is a heterocyclic group which may have a substituent. When n is 2 or 3, the plurality of R ² may be the same or different, and the plurality of R ³ may be the same or different.

In the general formula (1), R ⁵ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, a dialkylamino group which may have a substituent, or The aryl group which may have a substituent is shown.

Examples of the halogen atom represented by R ⁵ include the same halogen atoms as those represented by R ¹ , and among these, a fluorine atom and a chlorine atom are preferable. Examples of the alkyl group include those similar to the alkyl group represented by Ar ³ , and among these, a linear or branched alkyl group having 1 to 4 carbon atoms is preferable. Examples of the aryl group include the same aryl groups represented by Ar ¹ and Ar ² . Examples of the alkoxy group include linear alkoxy groups such as a methoxy group, an ethoxy group, and an n-propoxy group, and branched alkoxy groups such as an isopropoxy group. Among them, an alkoxy group having 1 to 4 carbon atoms is preferable. . Examples of the dialkylamino group include symmetric dialkylamino groups such as dimethylamino group, diethylamino group and diisopropylamino group, and asymmetric dialkylamino groups such as ethylmethylamino group and isopropylethylamino group. The dialkylamino group is preferred. Examples of the substituent that each of these groups may have include the same substituents that the aryl group represented by Ar ¹ and Ar ² may have.

In General formula (1), l shows the integer of 1-6. However, when 1 is 2 or more, a plurality of R ⁵ may be the same or different, and may form a divalent condensed ring group together with a naphthylene group to which these are bonded. Examples of the divalent fused ring group include a 1,2,3,4-tetrahydro-9,10-anthrylene group.

  Since the enamine compound represented by the general formula (1) has an excellent charge transport capability, the enamine compound represented by the general formula (1) is included in each of the layers 13 and 14 of the charge transport layer 15 as a charge transport material. Therefore, it is possible to realize the photosensitive member 1 having high sensitivity, excellent photoresponsiveness and chargeability, and capable of handling a high-speed electrophotographic process. Such good electrical characteristics of the photoreceptor 1 are maintained without being lowered even when the environment around the photoreceptor 1 such as temperature and humidity changes. Thus, since the photoreceptor 1 is excellent in environmental stability, it is possible to provide an image having sufficient photoresponsiveness and sufficient image density even in a low temperature environment.

Among the enamine compounds represented by the general formula (1), as a preferable compound, in the general formula (1),
Ar ¹ and Ar ² are each an aryl group optionally having one or more selected from a halogen atom, an alkyl group, an alkoxy group and a dialkylamino group as a substituent, or a nitrogen atom and a sulfur atom as a hetero atom A monocyclic or fused-ring heterocyclic group containing at least one selected from
Ar ³ is an aryl group which may have one or more selected from a halogen atom, an alkyl group, an alkoxy group, a dialkylamino group, a phenoxy group and a phenylthio group as a substituent, and an alkyl group and an alkoxy group as a substituent Alternatively, it may have an aryl group and the monocyclic or condensed cyclic heterocyclic group containing at least one selected from oxygen atom, nitrogen atom and sulfur atom as a hetero atom, and the alkyl moiety has 1 to 3 carbon atoms An aralkyl group or a cycloalkyl group having 5 to 7 carbon atoms,
R ¹ is a hydrogen atom, a halogen atom or an alkyl group having 1 to 4 carbon atoms which may have a halogen atom as a substituent;
One of R ² and R ³ is a hydrogen atom, and the other has one or more selected from a hydrogen atom, a thienyl group, a benzyl group, or a halogen atom and an alkoxy group having 1 to 4 carbon atoms as a substituent. An alkyl group having 1 to 4 carbon atoms,
Examples include enamine compounds in which R ⁴ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group.

で表されるエナミン化合物が挙げられる。 Among these enamine compounds, more preferred compounds are those represented by the general formula (1a)

The enamine compound represented by these is mentioned.

In the general formula (1a), Ar ⁴ , Ar ⁵ , R ⁵ and l have the same definitions as in the general formula (1). M represents 1 or 2.

In the general formula (1a), R ⁶ , R ⁷ and R ⁸ each have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. The dialkylamino group which may be substituted or the aryl group which may have a substituent is shown. Specific examples of each group represented by R ⁶ , R ⁷ and R ⁸ include the same groups as those represented by R ⁵ in the general formula (1). Moreover, as these substituents which may be possessed by each group, the same as the substituent which may have an aryl group represented by Ar ¹ and Ar ^2.

In general formula (1a), i, j, and k each represent an integer of 1 to 5. However, when i is 2 or more, the plurality of R ⁶ may be the same or different, and may form a monovalent fused ring group together with the phenyl group to which they are bonded. When j is 2 or more, the plurality of R ⁷ may be the same or different, and may form a monovalent fused ring group together with the phenyl group to which they are bonded. When k is 2 or more, the plurality of R ⁸ may be the same or different, and may form a monovalent fused ring group together with the phenyl group to which these are bonded. Examples of the monovalent fused ring group include a 5,6,7,8-tetrahydro-1-naphthyl group.

Among the enamine compounds represented by the general formula (1a), particularly preferable compounds include those represented by the general formula (1a):
Ar ⁴ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a thienyl alkyl group having 1 to 4 carbon atoms in the alkyl portion, or an alkyl group having 1 to 4 carbon atoms as a substituent, an alkoxy having 1 to 4 carbon atoms A phenyl group which may have a group or a C 2-8 dialkylamino group,
And Ar ⁵ is an alkyl group having 1 to 4 carbon atoms as a substituent, fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, dialkylamino group having 2 to 8 carbon atoms, phenylthio group, a phenoxy group Or an aryl group which may have a styryl group, a monocyclic or condensed cyclic heterocyclic group containing one or two selected from oxygen atom, nitrogen atom and sulfur atom as a hetero atom, carbon number of alkyl part Is an aralkyl group having 1 to 3 or a thienylalkyl group having 1 to 3 carbon atoms in the alkyl moiety,
Alternatively, the carbon atom to which the group = CAr ⁴ Ar ⁵ is bonded may have a divalent condensed cyclic aromatic ring group or an alkyl group having 1 to 4 carbon atoms as a substituent instead of the group = CAr ⁴ Ar ^5. A fused ring heterocyclic group containing at least one selected from an oxygen atom, a nitrogen atom and a sulfur atom as a hetero atom is bonded,
R ⁵ , R ⁶ and R ⁷ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms,
An enamine compound wherein R ⁸ is a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or a dialkylamino group having 2 to 8 carbon atoms (hereinafter referred to as enamine compound 1a ′); Is mentioned. Among these, enamine compounds represented by the following general formula (1b) are particularly preferable.

In general formula (1b), m is synonymous with the definition in general formula (1a). R ^8a represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include linear alkyl groups having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, and carbons such as an isopropyl group and a t-butyl group. Examples thereof include branched alkyl groups of 1 to 4. Moreover, as a C1-C4 alkoxy group, C1-C4 linear alkoxy groups, such as a methoxy group, an ethoxy group, and n-propoxy group, and C1-C4 branched chains, such as an isopropoxy group, And an alkoxy group.

  The enamine compound represented by the general formula (1a), the enamine compound 1a ′ and the enamine compound represented by the general formula (1b), particularly the enamine compound represented by the general formula (1b) is represented by the general formula (1). Among the enamine compounds to be produced, the synthesis is relatively easy and the yield is high, so that they can be produced at a relatively low cost. Therefore, the manufacturing cost of the photoreceptor 1 is reduced by using the enamine compound represented by the general formula (1a), preferably the enamine compound 1a ′, more preferably the enamine compound represented by the general formula (1b). Can do.

Among the enamine compounds represented by the general formula (1), as a particularly excellent compound from the viewpoint of characteristics, cost, productivity and the like, in the general formula (1), Ar ¹ and Ar ² are both phenyl groups, Ar ³ is a phenyl group, tolyl group, p-methoxyphenyl group, biphenylyl group, naphthyl group or thienyl group, and at least one of Ar ⁴ and Ar ⁵ is a phenyl group, p-tolyl group, p-methoxy group Examples thereof include a phenyl group, a naphthyl group, a thienyl group or a thiazolyl group, wherein R ¹ , R ² , R ³ and R ⁴ are all hydrogen atoms and n is 1.

  Specific examples of the enamine compound represented by the general formula (1) include, for example, Exemplified Compound Nos. 1 to 32 shown in Tables 1 to 32 below. 1-No. 220 can be mentioned, but the enamine compound represented by the general formula (1) is not limited thereto. In Tables 1 to 32, each exemplified compound is represented by a group corresponding to each group of the general formula (1). For example, Exemplified Compound Nos. 1 is an enamine compound represented by the following structural formula (4).

However, in the general formula (1), a compound in which a divalent aromatic ring group or heterocyclic group is bonded to the carbon atom to which the group = CAr ⁴ Ar ⁵ is bonded instead of the group = CAr ⁴ Ar ⁵ is exemplified. In some cases, these divalent groups are listed from the Ar ⁴ column to the Ar ⁵ column. In addition, among the enamine compounds in which n is 2 or 3 in the general formula (1), examples in which a plurality of groups represented by R ² are the same and a plurality of groups represented by R ³ are the same are exemplified. In the case, one each of R ² and R ³ is shown.

  The enamine compound represented by the general formula (1) can be produced, for example, as follows. First, by performing a dehydration condensation reaction between an aldehyde compound or a ketone compound represented by the following general formula (5) and a secondary amine compound represented by the following general formula (6), the following general formula (7) The enamine intermediate represented is produced.

（式中、Ａｒ^１、Ａｒ^２およびＲ^１は一般式（１）における定義と同義である。）

(In the formula, Ar ¹ , Ar ² and R ¹ have the same definitions as in general formula (1).)

（式中、Ａｒ^３、Ｒ^５およびｌは一般式（１）における定義と同義である。）

(In the formula, Ar ³ , R ⁵ and l have the same definitions as in general formula (1).)

(In the formula, Ar ¹ , Ar ² , Ar ³ , R ¹ , R ⁵ and l have the same definitions as in general formula (1).)

  This dehydration condensation reaction is performed, for example, as follows. In a suitable solvent, an aldehyde compound or a ketone compound represented by the general formula (5) and a secondary amine compound represented by the general formula (6) are added in approximately equimolar amounts and dissolved to prepare a solution. . Examples of the solvent used include aromatic hydrocarbons such as toluene, xylene and chlorobenzene, alcohols such as butanol, and ethers such as diethylene glycol dimethyl ether. A catalyst, for example, an acid catalyst such as p-toluenesulfonic acid, camphorsulfonic acid, pyridinium-p-toluenesulfonic acid or the like is added to the prepared solution, and the reaction is performed, for example, under heating. It is preferable that the addition amount of a catalyst is 1/10 (1/10)-1/1000 (1/1000) molar equivalent with respect to the aldehyde compound or ketone compound represented by General formula (5). More preferably, it is 1/25 (1/25) to 1/500 (1/500) molar equivalent, and more preferably 1/50 (1/50) to 1/200 (1/200). Molar equivalent. During the reaction, water is formed as a by-product and hinders the reaction. Therefore, it is preferable to remove the produced water from the system by azeotropic distillation with a solvent. As described above, the enamine intermediate represented by the general formula (7) can be produced in high yield.

  Next, an enamine-carbonyl intermediate represented by the following general formula (8) is produced by acylating the enamine intermediate represented by the general formula (7).

(In the formula, Ar ¹ , Ar ² , Ar ³ , R ¹ , R ⁵ and l have the same definitions as in general formula (1). R ¹¹ is represented by R ² or R ⁴ in general formula (1). Group.)

For example, among the enamine-carbonyl intermediates represented by the general formula (8), the enamine-aldehyde intermediate in which R ¹¹ is a hydrogen atom is obtained by converting the enamine intermediate represented by the general formula (7) by the Filsmeier reaction. It can be produced by formylation.

The Filsmeier reaction is performed, for example, as follows. In a suitable solvent, phosphorus oxychloride and N, N-dimethylformamide, N-methyl-N-phenylformamide or N, N-diphenylformamide are added to prepare a Vilsmeier reagent. Examples of the solvent used at this time include aprotic polar solvents such as N, N-dimethylformamide and halogenated hydrocarbons such as 1,2-dichloroethane. 1.0 mol equivalent of the enamine intermediate represented by the general formula (7) is added to the solution in which 1.0 to 1.3 mol equivalent of the Vilsmeier reagent is prepared, for example, 2 under heating at 60 to 110 ° C. Stir for ~ 8 hours to react. After completion of the reaction, hydrolysis is performed with an alkaline aqueous solution of 1 to 8 N (N). Examples of the alkaline aqueous solution used for the hydrolysis include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution. As described above, among the enamine-carbonyl intermediates represented by the general formula (8), an enamine-aldehyde intermediate in which R ¹¹ is a hydrogen atom can be produced in a high yield.

Further, among the enamine-carbonyl intermediates represented by the general formula (8), the enamine-keto intermediate in which R ¹¹ is a group other than a hydrogen atom is obtained by converting the enamine compound represented by the general formula (7) to Friedel. -It can manufacture by acylating by kraft acylation reaction.

  This Friedel-Craft acylation reaction is performed as follows, for example. In a suitable solvent, add 1.0 to 1.2 molar equivalent of Lewis acid and 1.0 molar equivalent of acyl halide represented by the following general formula (9), and stir for about 0.5 to 1 hour. A Friedel-Craft acylating reagent is prepared. Examples of the solvent used at this time include halogenated hydrocarbons such as 1,2-dichloroethane and dichloromethane, and aromatic hydrocarbons such as nitrobenzene. Examples of the Lewis acid include aluminum chloride, tin chloride, and zinc chloride.

(In the formula, R ¹¹ has the same definition as in general formula (8). X ¹ represents a halogen atom such as a chlorine atom or a bromine atom.)

To the solution in which 1.0 to 1.3 molar equivalent of Friedel-Craft acylating reagent is prepared, 1.0 molar equivalent of the enamine intermediate represented by the general formula (7) is added, for example, minus (−) 40 The reaction is allowed to stir at -80 ° C for 2-8 hours. After completion of the reaction, hydrolysis is performed with an alkaline aqueous solution of 1 to 8 N (N). Examples of the alkaline aqueous solution used for the hydrolysis include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution. As described above, among the enamine-carbonyl intermediates represented by the general formula (8), an enamine-keto intermediate in which R ¹¹ is a group other than a hydrogen atom can be produced in high yield.

Note that when manufacturing enamine compound of n = 0 in general formula (1), enamine represented by formula (8) - as carbonyl intermediate, to produce a compound of R ^{11 =} R ^4. Moreover, when manufacturing the enamine compound of n = 1-3 in General formula (1), the compound of R < ¹¹ > = R < ² > is manufactured as an enamine-carbonyl intermediate represented by General formula (8).

  Next, a Wittig-horner (reaction) in which an enamine-carbonyl intermediate represented by the general formula (8) is reacted with a Wittig reagent represented by the following general formula (10) or (11) under basic conditions ( An enamine compound represented by the general formula (1) can be produced by performing a Wittig-Horner reaction.

(In the formula, Ar ⁴ and Ar ⁵ have the same definitions as in general formula (1). R ¹² represents an alkyl group or an aryl group.)

(In the formula, Ar ⁴ , Ar ⁵ , R ² , R ³ , R ⁴ and n are as defined in the general formula (1). However, n is not 0. R ¹³ represents an alkyl group or an aryl group. .)

  The Wittig reagent represented by the general formulas (10) and (11) is appropriately selected and used according to the value of n in the general formula (1). For example, when producing an enamine compound with n = 0 in the general formula (1), a Wittig reagent represented by the general formula (10) is used. Moreover, when manufacturing the enamine compound of n = 1-3 in General formula (1), the Wittig reagent represented by General formula (11) is used.

In the general formulas (10) and (11), the alkyl group represented by R ¹² and R ¹³ is a linear alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group or an n-propyl group, isopropyl And a branched alkyl group having 1 to 4 carbon atoms such as a group. Examples of the aryl group include 1- or 2-ring aryl groups such as a phenyl group, a naphthyl group, and a biphenylyl group.

  The Wittig-Horner reaction between the enamine-carbonyl intermediate represented by the general formula (8) and the Wittig reagent represented by the general formula (10) or (11) is performed, for example, as follows. In a suitable solvent, 1.0 mol equivalent of the enamine-carbonyl intermediate represented by the general formula (8) and 1.0 to 1.20 mol of the Wittig reagent represented by the general formula (10) or (11) An equivalent amount and 1.0 to 1.5 molar equivalents of a metal alkoxide base are added and, for example, the reaction is allowed to stir for 2 to 8 hours with heating at room temperature or 30 to 60 ° C. Solvents used at this time include aromatic hydrocarbons such as toluene and xylene, ethers such as diethyl ether, tetrahydrofuran and ethylene glycol dimethyl ether, and aprotic polar solvents such as N, N-dimethylformamide and dimethyl sulfoxide. Is mentioned. Examples of the metal alkoxide base include potassium t-butoxide, sodium ethoxide, sodium methoxide and the like.

  As described above, the enamine compound represented by the general formula (1) can be produced in high yield. The enamine compound represented by the general formula (1) can be easily isolated and purified from the reaction mixture by a usual separation means such as a solvent extraction method, a recrystallization method, or column chromatography, and obtained as a high purity compound. be able to.

  The enamine compounds represented by the general formula (1) are exemplified by the exemplified compound Nos. 1-No. One selected from the group consisting of 220 may be used alone, or two or more may be used in combination.

As the binder resin for the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14, those having excellent compatibility with the enamine compound represented by the general formula (1) used as the charge transport material are suitably used. . Examples of such binder resins include vinyl polymer resins such as polymethyl methacrylate resin, polystyrene resin, and polyvinyl chloride resin, and copolymer resins containing two or more of repeating units constituting them, and polycarbonate resins. Polyester resin, polyester carbonate resin, polysulfone resin, phenoxy resin, epoxy resin, silicone resin, polyarylate resin, polyamide resin, polyether resin, polyurethane resin, polyacrylamide resin and phenol resin. Moreover, the thermosetting resin which partially bridge | crosslinked these resin is also mentioned. One kind of these resins may be used alone, or two or more kinds thereof may be mixed and used. Among the resins described above, polystyrene resin, polycarbonate resin, polyarylate resin, and polyphenylene oxide have a volume resistivity of 10 ¹³ Ω · cm or more and excellent electrical insulation, and also have film properties and potential characteristics. Since it is excellent, it is preferably used.

  The weight (A) of the enamine compound represented by the general formula (1) contained as the charge transport material in each layer constituting the charge transport layer 15, that is, the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14 It is preferable that the ratio (B / A) of the weight (B) of the binder resin to is 1.2 or more and 3.0 or less. In particular, in the surface-side charge transport layer 14 serving as the surface layer of the photoreceptor 1, the ratio B / A is preferably 1.2 or more and 3.0 or less. Thereby, the printing durability of the charge transport layer 15 can be improved, and the durability of the photoreceptor 1 can be improved.

  However, when the ratio of the binder resin is increased as described above, the ratio of the enamine compound represented by the general formula (1) contained as the charge transport material is decreased as a result. When a conventionally known charge transport material is used, the ratio of the weight of the binder resin to the weight of the charge transport material (binder resin / charge transport material) is similarly 1.2 or more in each of the layers 13 and 14 of the charge transport layer 15. If so, the photoresponsiveness of the photoconductor may be insufficient and image defects may occur. On the other hand, since the enamine compound represented by the general formula (1) has an excellent charge transport capability, the ratio B / A is 1.2 or more, and the binder in each of the layers 13 and 14 of the charge transport layer 15 is used. Even if the ratio of the resin is increased, the photoconductor 1 exhibits sufficiently high photoresponsiveness and can provide a high-quality image. Therefore, in the photoreceptor 1, the ratio B / A is set to 1.2 or more without decreasing the photoresponsiveness, the printing durability of the layers 13 and 14 of the charge transport layer 15 is improved, and the mechanical durability is further increased. Can be improved.

When the ratio B / A is less than 1.2, the binder resin ratio becomes too low, for example, it becomes difficult to set the η _HU of the surface-side charge transport layer 14 to 47.0% or more. There is a possibility that the printability is lowered and the amount of film loss of the photosensitive layer 16 is increased, so that the chargeability of the photoreceptor 1 is lowered. On the other hand, if the ratio B / A exceeds 3.0, the binder resin ratio becomes too high, and the sensitivity of the photoreceptor 1 may be lowered. Further, when the charge transport layer 15 is formed by the dip coating method, if the ratio B / A exceeds 3.0, the viscosity of the coating solution increases, the coating speed decreases, and the productivity is remarkably deteriorated. Further, if the amount of the solvent in the coating solution is increased in order to suppress the increase in the viscosity of the coating solution, a brushing phenomenon occurs, and the formed charge transport layer 15 may be clouded.

  Each of the layers 13 and 14 of the charge transport layer 15 may contain a charge transport material other than the enamine compound represented by the general formula (1) as long as the preferable characteristics of the present invention are not impaired. Examples of charge transport materials that can be used in combination with the enamine compound represented by the general formula (1) include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives. , Bisimidazolidine derivatives, styryl compounds, hydrazone compounds, polycyclic aromatic compounds, indole derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamines Derivatives, triarylmethane derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, and the like can be given. Also included are polymers having groups derived from these compounds in the main chain or side chain, such as poly (N-vinylcarbazole), poly (1-vinylpyrene), poly (9-vinylanthracene) and the like.

  In addition, various additives may be added to the layers 13 and 14 of the charge transport layer 15 within a range that does not impair the preferable characteristics of the present invention. For example, a plasticizer or a leveling agent may be added to improve the film formability, flexibility, or surface smoothness. Further, in order to enhance mechanical strength and improve electrical characteristics, fine particles of an inorganic compound or an organic compound may be added. Examples of the plasticizer include dibasic acid esters such as phthalate esters, fatty acid esters, phosphate esters, chlorinated paraffins, and epoxy type plasticizers. Examples of the leveling agent include a silicone leveling agent.

  Each of the layers 13 and 14 of the charge transport layer 15 is, for example, an enamine compound represented by the general formula (1) and a binder resin in an appropriate solvent, as in the case where the charge generation layer 12 is formed by coating, and If necessary, charge transport materials other than the enamine compound represented by the general formula (1) and various additives are dissolved or dispersed to prepare a charge transport layer coating solution, and the resulting coating solution generates charges. It is formed by coating on the surface of the layer 12 or the charge generation layer side charge transport layer 13.

  Solvents used in the coating solution for the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane, tetrahydrofuran, dioxane and dimethoxymethyl ether. Examples include ethers and aprotic polar solvents such as N, N-dimethylformamide. Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment. One of these solvents may be used alone, or two or more thereof may be mixed and used. In addition, a solvent such as alcohols, acetonitrile, or methyl ethyl ketone can be further added to the above-described solvent as necessary.

  Examples of the coating method for the charge transport layer coating solution include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method. Among these coating methods, the dip coating method is particularly excellent in various respects as described above, and thus is preferably used when forming the layers 13 and 14 of the charge transport layer 15.

  The layer thicknesses of the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14 are each preferably 1 μm or more and 30 μm or less, and more preferably 5 μm or more and 20 μm or less. When the layer thickness of the charge generation layer side charge transport layer 13 is less than 1 μm, the charge generation layer side charge transport layer 13 functions integrally with the surface side charge transport layer 14, and the charge generation layer side charge transport layer 13 is provided. The effect may not be obtained sufficiently. Conversely, when the layer thickness of the charge generation layer side charge transport layer 13 exceeds 30 μm, the sum of the layer thickness of the surface side charge transport layer 14, that is, the layer thickness of the entire charge transport layer 15 becomes too large, and the resolution decreases. There is a fear. If the surface-side charge transport layer 14 has a thickness of less than 1 μm, all of the surface-side charge transport layer 14 is before the electrical life of the photoreceptor 1 due to wear, that is, the sensitivity of the photoreceptor 1 is reduced due to repeated use. There is a possibility that it will disappear before it can no longer be used, and there is a possibility that a sufficient life will not be obtained. On the contrary, if the layer thickness of the surface-side charge transport layer 14 exceeds 30 μm, the sum of the layer thickness of the charge generation layer-side charge transport layer 13, that is, the layer thickness of the entire charge transport layer 15 becomes too large, and the resolution decreases. There is a fear. In order to sufficiently extend the life of the photoreceptor 1, the layer thickness of the surface side charge transport layer 14 is preferably larger than the layer thickness of the charge generation layer side charge transport layer 13. As a result, the surface-side charge transport layer 14 can be prevented from disappearing before the electrical life of the photoreceptor 1, and the life of the photoreceptor 1 can be further prolonged.

  The total thickness of the charge transport layer 15, that is, the sum of the layer thickness of the charge generation layer side charge transport layer 13 and the layer thickness of the surface side charge transport layer 14 is preferably 5 μm or more and 40 μm or less. Is 10 μm or more and 30 μm or less. If the total thickness of the charge transport layer 15 is less than 5 μm, the charge holding ability of the photoreceptor 1 may be lowered. If the total thickness of the charge transport layer 15 exceeds 40 μm, the resolution of the photoreceptor 1 may be lowered.

  Each layer of the photosensitive layer 16, that is, the charge generation layer 12, the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14 is intended to improve sensitivity and further suppress a rise in residual potential and fatigue due to repeated use. In addition, one or two or more sensitizers such as an electron accepting substance and a dye may be added within a range that does not impair the preferable characteristics of the present invention.

  Examples of the electron acceptor include succinic anhydride, maleic anhydride, phthalic anhydride, acid anhydrides such as 4-chloronaphthalic anhydride, cyano compounds such as tetracyanoethylene and terephthalmalondinitrile, and 4-nitrobenzaldehyde. Aldehydes, anthraquinones, anthraquinones such as 1-nitroanthraquinone, polycyclic or heterocyclic nitro compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, or diphenoquinone compounds An electron-withdrawing material can be used. Moreover, what polymerized these electron-withdrawing materials can also be used.

  As the dye, for example, an organic photoconductive compound such as xanthene dye, thiazine dye, triphenylmethane dye, quinoline pigment or copper phthalocyanine can be used. These organic photoconductive compounds function as optical sensitizers.

  Further, an antioxidant or an ultraviolet absorber may be added to each of the layers 12, 13, and 14 of the photosensitive layer 16. In particular, it is preferable to add an antioxidant or an ultraviolet absorber to each of the layers 13 and 14 of the charge transport layer 15. Accordingly, deterioration due to an oxidizing gas such as ozone or nitrogen oxide can be suppressed, and electrical durability can be improved. Moreover, the stability of the coating liquid when forming each layer by coating can be enhanced.

  Examples of the antioxidant include phenolic compounds, hydroquinone compounds, tocopherol compounds, amine compounds, and the like. Among these, hindered phenol derivatives, hindered amine derivatives, or mixtures thereof are preferably used. The total amount of the antioxidant used is preferably 0.1 parts by weight or more and 50 parts by weight or less per 100 parts by weight of the charge transport material contained in the charge transport layer 15. If the amount of the antioxidant used per 100 parts by weight of the charge transport material is less than 0.1 parts by weight, the effect of improving the stability of the coating solution and the electrical durability of the photoreceptor may not be sufficiently exhibited. On the other hand, if it exceeds 50 parts by weight, there is a risk of adversely affecting the characteristics of the photoreceptor.

The layers constituting the photosensitive layer 16, that is, the charge generation layer 12, the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14 are sequentially applied and formed by the above-described method or every time each layer is applied. It is dried by using a dryer that uses natural drying or hot air, far infrared rays or the like as a heat source. The drying temperature at this time is appropriately selected according to various conditions such as the solvent used in the coating solution and the thickness of each layer, but is preferably 50 ° C. or higher and 140 ° C. or lower, and preferably 80 ° C. or higher and 130 ° C. or lower. More preferably, it is 80 degreeC or more and 120 degrees C or less especially. When the drying temperature is less than 50 ° C., the time required for drying the coating film becomes long and the productivity is lowered. On the other hand, if the drying temperature exceeds 140 ° C., the electrical characteristics deteriorate due to repeated use, and the quality of the obtained image may be deteriorated. In addition, when forming the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14, the drying conditions are selected in consideration of η _HU within the above range.

  FIG. 3 is a partial cross-sectional view showing a simplified configuration of the electrophotographic photosensitive member 2 according to the second embodiment of the present invention. The electrophotographic photoreceptor 2 of the present embodiment is similar to the electrophotographic photoreceptor 1 of the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. What should be noted in the electrophotographic photoreceptor 2 is that an intermediate layer 17 is provided between the conductive substrate 11 and the photosensitive layer 16.

  When there is no intermediate layer 17 between the conductive substrate 11 and the photosensitive layer 16, charges are injected from the conductive substrate 11 to the photosensitive layer 16, the chargeability of the photosensitive layer 16 decreases, and the surface other than the exposed portion. Charges may be reduced and defects such as fogging may occur in the image. In particular, when an image is formed using a reversal development process, toner adheres to a portion where the surface charge has been reduced by exposure, and a toner image is formed. An image fogging called black spots where toner adheres to the surface and minute black spots are formed may cause a significant deterioration in image quality. As described above, when there is no intermediate layer 17 between the conductive substrate 11 and the photosensitive layer 16, the chargeability in a minute region is reduced due to a defect in the conductive substrate 11 or the photosensitive layer 16, and black An image fogging such as a pocket may occur, resulting in a significant image defect.

  In the photoreceptor 2 of this embodiment, since the intermediate layer 17 is provided between the conductive substrate 11 and the photosensitive layer 16 as described above, injection of charges from the conductive substrate 11 to the photosensitive layer 16 is performed. Can be prevented. Accordingly, it is possible to prevent the chargeability of the photosensitive layer 16 from being lowered, to suppress the reduction of the surface charge at portions other than the exposed portion, and to prevent the occurrence of defects such as fogging on the image. Further, by providing the intermediate layer 17, it is possible to cover defects on the surface of the conductive substrate 11 and obtain a uniform surface, so that the film formability of the photosensitive layer 16 can be improved. Further, since the intermediate layer 17 functions as an adhesive that bonds the conductive substrate 11 and the photosensitive layer 16, peeling of the photosensitive layer 16 from the conductive substrate 11 can be suppressed.

  However, if the intermediate layer 17 is provided between the conductive substrate 11 and the photosensitive layer 16 as described above, the sensitivity of the photoreceptor may be lowered. However, since the charge transport layer 15 of the photoreceptor 2 of the present embodiment contains the enamine compound represented by the general formula (1) having an excellent charge transport capability, the photoreceptor 2 includes the intermediate layer 17. There is no reduction in sensitivity due to the provision. That is, in the photoreceptor 2 of the present embodiment, the intermediate layer 17 can be provided without reducing the sensitivity. Therefore, in this embodiment, in various environments, it is excellent in electrical characteristics such as sensitivity and photoresponsiveness, mechanical durability and electrical durability, and stable high-quality images without fogging over a long period of time. The photoconductor 2 that can be provided can be realized.

  As the intermediate layer 16, a resin layer made of various resin materials, an alumite layer, or the like is used. The resin material constituting the resin layer includes polyethylene resin, polypropylene resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, silicone resin, polyvinyl butyral resin, and polyamide. Examples thereof include resins such as resins, and copolymer resins including two or more of repeating units constituting these resins. Moreover, casein, gelatin, polyvinyl alcohol, ethyl cellulose, and the like are also included. Among these resins, it is preferable to use a polyamide resin, and it is particularly preferable to use an alcohol-soluble nylon resin. Preferable alcohol-soluble nylon resins include, for example, so-called copolymer nylon obtained by copolymerizing 6-nylon, 6,6-nylon, 6,10-nylon, 11-nylon, 12-nylon, and the like, and N-alkoxymethyl-modified. Examples thereof include resins obtained by chemically modifying nylon, such as nylon and N-alkoxyethyl-modified nylon.

  The intermediate layer 17 may contain particles such as metal oxide particles. By containing these particles in the intermediate layer 17, the volume resistance value of the intermediate layer 17 can be adjusted, and the effect of preventing charge injection from the conductive substrate 11 to the photosensitive layer 16 can be enhanced. Further, the electrical characteristics of the photoreceptor 2 can be maintained under various environments, and the environmental stability can be improved. Examples of metal oxide particles include particles of titanium oxide, aluminum oxide, aluminum hydroxide, tin oxide, and the like.

  The intermediate layer 17 can be formed by, for example, preparing an intermediate layer coating solution by dissolving or dispersing the above-described resin in an appropriate solvent and applying the coating solution to the surface of the conductive substrate 11. When the intermediate layer 17 contains particles such as the above-described metal oxide particles, for example, these particles are dispersed in a resin solution obtained by dissolving the above-described resin in a suitable solvent to apply the intermediate layer. The intermediate layer 17 can be formed by preparing a liquid and applying this coating liquid to the surface of the conductive substrate 11.

  Examples of the solvent for the intermediate layer coating solution include water and various organic solvents. One of these solvents may be used alone, or two or more thereof may be mixed and used as a mixed solvent. As the single solvent, alcohols such as water, methanol, ethanol and butanol are preferably used. Mixed solvents include water and alcohols, two or more alcohols, ketones such as acetone and acetone, ethers such as dioxolane, chlorinated solvents such as dichloroethane, chloroform, and trichloroethane. And the like are preferably used. Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

  As a method for dispersing the particles such as the metal oxide particles in the resin solution, a general method using a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, a paint shaker, or the like can be used.

  In the intermediate layer coating solution, the ratio (C / D) of the total weight (C) of the resin and metal oxide to the weight (D) of the solvent used in the intermediate layer coating solution is 1/99 or more and 40 / 60 or less, more preferably 2/98 or more and 30/70 or less. The ratio (E / F) of the weight (E) of the resin to the weight (F) of the metal oxide in the intermediate layer coating solution is preferably 1/99 or more and 90/10 or less, more preferably 5 / 95 or more and 70/30 or less.

  Examples of the coating method of the intermediate layer coating liquid include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method. Among these, in particular, the dip coating method is relatively simple as described above, and is excellent in productivity and cost. Therefore, it is preferably used when forming the intermediate layer 17.

  The thickness of the intermediate layer 17 is preferably 0.01 μm or more and 20 μm or less, more preferably 0.05 μm or more and 10 μm or less. If the thickness of the intermediate layer 17 is less than 0.01 μm, the intermediate layer 17 substantially does not function as the intermediate layer 17, and the surface of the conductive substrate 11 cannot be covered to obtain a uniform surface property. There is a possibility that charge injection from the substrate 11 to the photosensitive layer 16 may not be prevented, and the chargeability of the photosensitive layer 16 may be reduced. Making the thickness of the intermediate layer 17 greater than 20 μm makes it difficult to form the intermediate layer 17 when the intermediate layer 17 is formed by dip coating, and makes the photosensitive layer 16 uniformly on the intermediate layer 17. Since it cannot be formed and the sensitivity of the photoreceptor 2 may be lowered, it is not preferable.

  In the present embodiment, various additives such as plasticizers, leveling agents, fine particles of inorganic compounds or organic compounds are added to the layers 13 and 14 of the charge transport layer 15 as in the first embodiment. May be. Further, an additive such as a sensitizer such as an electron accepting substance or a dye, an antioxidant, or an ultraviolet absorber may be added to each of the layers 12, 13, and 14 of the photosensitive layer 16.

  In the electrophotographic photoreceptors 1 and 2 according to the first and second embodiments described above, the charge transport layer 15 is composed of two layers of the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14. However, the present invention is not limited to this, and it may be composed of three or more layers. In this case, if another charge transport layer containing the enamine compound represented by the general formula (1) is further provided between the charge generation layer side charge transport layer 13 and the surface side charge transport layer 14. Good. By comprising three or more layers in this way, it becomes easy to adjust electrical characteristics such as photoresponsiveness and sensitivity of the photoreceptor. However, since the charge transport layer 15 is composed of two layers as in the first and second embodiments, the number of layers to be formed is smaller, so that the productivity, manufacturing cost, and yield are superior.

  FIG. 4 is a side view showing a simplified configuration of the image forming apparatus 30 according to the third embodiment of the present invention. The image forming apparatus 30 includes the photoreceptor 1 according to the first embodiment. An image forming apparatus 30 exemplified as the present embodiment is a laser printer 30 including a semiconductor laser element as a light source of an exposure unit.

  The laser printer 30 includes the above-described photoconductor 1, semiconductor laser element 31, rotating polygon mirror 32, imaging lens 34, mirror 35, charger 36 as charging means, developing device 37 as developing means, transfer paper cassette 38, It includes a paper feed roller 39, a registration roller 40, a transfer charger 41 as a transfer means, a separation charger 42, a conveyor belt 43, a fixing device 44, a paper discharge tray 45, and a cleaner 46 as a cleaning means. The semiconductor laser element 31, the rotary polygon mirror 32, the imaging lens 34, and the mirror 35 constitute an exposure unit 49. The cleaner 46 is provided with a static elimination lamp (not shown).

  The photoreceptor 1 is mounted on the laser printer 30 so that it can be rotated around the axis in the direction of the arrow 47 by a driving means (not shown). The semiconductor laser element 31 emits a laser beam 33 toward the rotary polygon mirror 32 in accordance with an instruction from a control unit (not shown). The laser beam 33 emitted from the semiconductor laser element 31 is repeatedly scanned by the rotary polygon mirror 32 in the longitudinal direction of the photoconductor 1 which is the main scanning direction with respect to the surface of the photoconductor 1. The imaging lens 34 has f-θ characteristics, and the laser beam 33 is reflected by the mirror 35 to form an image on the surface of the photoreceptor 1 to expose the surface of the photoreceptor 1. The surface of the photoconductor 1 is exposed according to image information by rotating the photoconductor 1 and scanning the laser beam 33 as described above to form an image.

  The charger 36, the developer 37, the transfer charger 41, the separation charger 42, and the cleaner 46 are provided in this order from the upstream side to the downstream side in the rotation direction of the photosensitive member 1 indicated by an arrow 47. . The charger 36 is provided upstream of the image forming point of the laser beam 33 in the rotation direction of the photoconductor 1 and uniformly charges the surface of the photoconductor 1. The surface of the photoreceptor 1 thus charged is exposed with the laser beam 33 from the exposure means 49. As a result, there is a difference between the charge amount of the part exposed by the laser beam 33 and the charge amount of the part not exposed, and an electrostatic latent image is formed. As the charger 36, for example, a corona charger is used. The charger 36 is not limited to this, and may be a corotron charger, a scorotron charger, a sawtooth charger, a roller charger, or the like.

  The developing device 37 is provided on the downstream side in the rotation direction of the photosensitive member 1 with respect to the image forming point of the laser beam 33, and supplies toner to the surface of the photosensitive member 1 on which the electrostatic latent image is formed. Develop as an image. As the developing device 37, for example, a contact type developing means is used. The developing device 37 is not limited to this, and may be a non-contact type developing unit, or may be a combination of a contact type developing unit and a non-contact type developing unit.

  The transfer paper 48 accommodated in the transfer paper cassette 38 is taken out one by one by a paper feed roller 39, and in synchronization with the exposure of the photoconductor 1 by the registration roller 40, the photoconductor 1 is further rotated than the developing device 37. The transfer charging device 41 is provided on the downstream side in the direction. The transfer charger 41 transfers the toner image to the transfer paper 48 by applying a charge having a polarity opposite to that of the toner image. In this embodiment, the transfer charger 41 is a non-contact type transfer unit, and is realized by, for example, a corona charger. The transfer charger 41 is not limited to this, and may be a contact-type transfer unit. As the contact-type transfer means, for example, a transfer roller is provided, and a toner image is transferred to the transfer paper 48 by applying a voltage to the transfer roller while the transfer roller is pressed against the photoreceptor 1 via the transfer paper 48. Things can be used. The separation charger 42 is provided on the further downstream side in the rotation direction of the photoreceptor 1 than the transfer charger 41 and in the vicinity of the transfer charger 41, and neutralizes the transfer paper 48 onto which the toner image has been transferred, thereby removing the photoreceptor 1. Separate from.

  The transfer paper 48 separated from the photoreceptor 1 is fed to the transport belt 43 and transported to the fixing device 44 by the transport belt 43. The fixing device 44 fixes the toner image to the transfer paper 48 by heating or heating and pressurizing the transfer paper 48 to which the toner image is transferred. The transfer paper 48 on which the image is formed in this manner is discharged toward the paper discharge tray 45.

  The cleaner 46 is provided further on the downstream side in the rotation direction of the photoconductor 1 than the separation charger 42 and on the upstream side in the rotation direction of the photoconductor 1 with respect to the charger 36, and cleans the surface of the photoconductor 1. Foreign matter such as residual toner and paper dust of the transfer paper 48 is removed. The cleaner 46 is realized by, for example, a blade cleaner that includes a blade as a cleaning member that contacts the photoreceptor surface 1 and cleans the photoreceptor surface 1. The cleaner 46 is not limited to this, and may be a brush cleaner including a brush as a cleaning member. A neutralizing lamp (not shown) provided together with the cleaner 46 neutralizes the surface of the photoreceptor 1 after cleaning, and the electrostatic latent image disappears.

  In the laser printer 30, an image is formed as follows. First, in response to an instruction from a control unit (not shown), the photosensitive member 1 is rotationally driven in the direction of the arrow 47 and the surface thereof is charged by the charger 36. Next, the photosensitive member 1 is exposed by the exposure unit 49 in accordance with an instruction from the control unit, and an electrostatic latent image is formed on the surface of the photosensitive member 1. Further, in synchronization with the exposure of the photosensitive member 1, the transfer paper 48 is supplied to the transfer position between the transfer / transfer device 41 and the photosensitive member 1 by the registration roller 40.

  Next, the electrostatic latent image is developed by the developing device 37 and a toner image is formed on the surface of the photoreceptor 1. The formed toner image is transferred to the transfer paper 48 by the transfer charger 42. The transfer paper 48 onto which the toner image has been transferred is transported to the fixing device 44 by the transport belt 43 and is heated and pressurized. As a result, the toner image is fixed on the transfer paper 48 to form an image. The transfer paper 48 on which the image is formed in this manner is discharged to the paper discharge tray 45. On the other hand, after the toner image is transferred to the transfer paper 48, the surface of the photoreceptor 1 that further rotates in the direction of the arrow 47 is cleaned by a cleaner 46 and further unloaded by a charge eliminating lamp. As a result, the electrostatic latent image on the surface of the photoreceptor 1 disappears. Thereafter, the photosensitive member 1 is further rotated and a series of operations starting from charging of the photosensitive member 1 is repeated. As described above, images are continuously formed.

The surface layer of the photoconductor 1 provided in the laser printer 30, that is, the surface-side charge transport layer 14 has an elastic work factor η _HU set in the above-described preferable range, so that external stress is applied by a cleaning blade of the cleaner 46. Elastic recovery is likely to occur. For this reason, the amount of film reduction of the photoreceptor 1 is reduced, and the occurrence of film scratches is also reduced, so that the surface of the photoreceptor 1 is kept smooth. Further, the photoreceptor 1 provided in the laser printer 30 contains the enamine compound represented by the general formula (1) in the charge transport layer 15 as described above, and has good electrical characteristics and excellent environmental stability. 30 can form a high-quality image even in a low-temperature and low-humidity environment, for example.

  Therefore, a highly reliable image forming apparatus 30 that can provide a high-quality image free of scratches and density unevenness over a long period of time in various environments is realized. Further, the life of the photosensitive member 1 is long, and it is not necessary to adjust the charging potential by the charger 36 according to the surrounding environment, and a simple configuration is sufficient. Therefore, the image forming apparatus 30 with low cost and low maintenance frequency can be obtained. Realized.

  The image forming apparatus according to the present invention is not limited to the configuration of the laser printer 30 shown in FIG. 4 described above, and any other type can be used as long as the photoconductor according to the present invention can be used. It may be a configuration.

  For example, when a photoconductor 1 having a small outer diameter of 40 mm or less is used, the separation charger 42 need not be provided. Further, by devising the timing of applying a high voltage such as a developing bias voltage to the photosensitive member 1, it is possible to adopt a configuration in which no static elimination lamp is provided. In particular, in the case of an image forming apparatus using a small diameter of 40 mm or less as the photoreceptor 1, a low-speed low-end printer, etc., in order to suppress an increase in the size of the apparatus and an increase in manufacturing cost, the static elimination is performed as described above. It is preferable that the lamp is not provided.

  Further, the photosensitive member 1 may be formed integrally with at least one of the charger 36, the developing unit 37, and the cleaner 46 so as to be a process cartridge that can be attached to and detached from the laser printer 30. For example, a process cartridge in which all of the photosensitive member 1, the charger 36, the developing device 37 and the cleaner 46 are incorporated, a process cartridge in which the photosensitive member 1, the charger 36 and the developing device 37 are incorporated, and the photosensitive member 1 and the cleaner 46. Can be configured, a process cartridge incorporating the photosensitive member 1 and the developing device 37, or the like. By using a process cartridge in which several members are integrated in this way, maintenance management of the apparatus is facilitated.

  Further, the photoconductor is not limited to the photoconductor 1 of the first embodiment, and any photoconductor according to the present invention can be used. For example, the photoconductor 2 of the second embodiment may be used. .

  Hereinafter, although the present invention will be described in more detail using examples and comparative examples, the present invention is not limited to the following description.

  First, a photoreceptor prepared as an example and a comparative example by forming a photosensitive layer on an aluminum cylindrical conductive substrate having an outer diameter of 30 mm and a longitudinal length of 340 mm under various conditions will be described.

Example 1
10 parts by weight of titanium oxide (trade name: TTO55A, manufactured by Ishihara Sangyo Co., Ltd.) and 10 parts by weight of copolymer nylon (trade name: CM8000, manufactured by Toray Industries, Inc.), 159 parts by weight of methanol and 106 parts by weight of 1,3-dioxolane In addition to the mixed solvent, an intermediate layer coating solution was prepared by dispersing for 8 hours with a paint shaker. The coating solution was filled in the coating tank, the conductive substrate was immersed in the coating tank, pulled up, and naturally dried to form an intermediate layer having a layer thickness of 1 μm.

  Next, a clear diffraction peak is shown at least at a Bragg angle 2θ (error: 2θ ± 0.2 °) 27.2 ° in an X-ray diffraction spectrum for Cu-Kα characteristic X-ray (wavelength: 1.54Å) as a charge generation material. 2 parts by weight of crystalline oxotitanium phthalocyanine crystal, 1 part by weight of polyvinyl butyral resin (trade name: ESREC BM-2, manufactured by Sekisui Chemical Co., Ltd.) and 97 parts by weight of methyl ethyl ketone are mixed and dispersed with a paint shaker Thus, a charge generation layer coating solution was prepared. This coating solution was applied onto the previously formed intermediate layer by the same dip coating method as that for the intermediate layer, and naturally dried to form a charge generation layer having a layer thickness of 0.4 μm.

  Subsequently, the exemplified compound No. 1 shown in Table 9 above as a charge transporting substance. 5 parts by weight of 61 enamine compound, 9 parts by weight of polycarbonate resin G400 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) as the binder resin, and Sumizer BHT (trade name, manufactured by Sumitomo Chemical Co., Ltd.) 0.05 as the antioxidant The charge generation layer side charge transport layer coating solution was prepared using 47 parts by weight of tetrahydrofuran as a solvent. This coating solution is applied onto the previously formed charge generation layer by the same dip coating method as that for the intermediate layer, and heated at a temperature of 130 ° C. for 1 hour to form a charge generation layer side charge transport layer having a thickness of 10 μm. Formed.

Subsequently, the exemplified compound No. 1 shown in Table 9 above as a charge transporting substance. 5 parts by weight of 61 enamine compound, 9 parts by weight of polycarbonate resin TS2050 (trade name, manufactured by Teijin Kasei Co., Ltd.) as the binder resin, and Sumilyzer BHT (trade name, manufactured by Sumitomo Chemical Co., Ltd.) 0.05 as the antioxidant A coating solution for a surface-side charge transport layer was prepared using 47 parts by weight of tetrahydrofuran as a solvent. This coating solution is applied onto the charge generation layer side charge transport layer formed earlier by the same dip coating method as that for the intermediate layer, and heated at a temperature of 130 ° C. for 1 hour to form a surface side charge having a layer thickness of 18 μm. A transport layer was formed, and a charge transport layer having a total layer thickness of 28 μm was formed.
The photoreceptor of Example 1 was produced as described above.

(Example 2)
In forming the charge generation layer side charge transport layer and the surface side charge transport layer, each of Exemplified Compound Nos. Instead of the enamine compound 61, Exemplified Compound Nos. An electrophotographic photosensitive member of Example 2 was produced in the same manner as in Example 1 except that 1 enamine compound was used.

(Example 3)
In the formation of the charge generation layer side charge transport layer and the surface side charge transport layer, each of Exemplified Compound Nos. In place of the enamine compound 61, Exemplified Compound Nos. An electrophotographic photoreceptor of Example 3 was produced in the same manner as in Example 1 except that 106 enamine compound was used.

Example 4
In forming the surface-side charge transport layer, Exemplified Compound No. 1 is used as a charge transport material. In place of the enamine compound 61, Exemplified Compound Nos. An electrophotographic photosensitive member of Example 4 was produced in the same manner as in Example 1 except that 1 enamine compound was used.

(Example 5)
Example 5 is the same as Example 1 except that polycarbonate resin GH503 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) is used instead of polycarbonate resin TS2050 (manufactured by Teijin Chemicals Co., Ltd.) in forming the surface-side charge transport layer. An electrophotographic photoreceptor was prepared.

(Example 6)
Example 6 was performed in the same manner as in Example 1 except that polycarbonate resin GF700 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) was used instead of polycarbonate resin TS2050 (manufactured by Teijin Chemicals Limited) in forming the surface-side charge transport layer. An electrophotographic photoreceptor was prepared.

(Example 7)
In the same manner as in Example 1 except that polycarbonate resin B300 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) is used instead of polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.) in forming the charge generation layer side charge transport layer. The electrophotographic photoreceptor of Example 7 was produced.

(Example 8)
In the same manner as in Example 1 except that polyester resin Vylon 290 (trade name, manufactured by Toyobo Co., Ltd.) is used instead of polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.) in forming the charge generation layer side charge transport layer. The electrophotographic photoreceptor of Example 8 was produced.

Example 9
In forming the charge generation layer side charge transport layer, a polyester resin Vylon 290 (trade name, manufactured by Toyobo Co., Ltd.) is used instead of the polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.). An electrophotographic photosensitive member of Example 9 was produced in the same manner as in Example 1 except that polycarbonate resin GH503 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) was used instead of resin TS2050 (manufactured by Teijin Chemicals Limited).

(Example 10)
When forming the charge generation layer side charge transport layer, the binder resin is replaced with 9 parts by weight of polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.), two types of polycarbonate resins, G400 (manufactured by Idemitsu Kosan Co., Ltd.), 4.5 wt. Example 10 and the electrophotographic photosensitive member of Example 10 were produced in the same manner as in Example 1 except that 4.5 parts by weight of TS2050 (manufactured by Teijin Chemicals Ltd.) was used.

(Example 11)
An electrophotographic photoreceptor of Example 11 was produced in the same manner as in Example 1 except that the amount of polycarbonate resin TS2050 (manufactured by Teijin Chemicals Ltd.) was changed to 10 parts by weight when forming the surface-side charge transport layer. .

(Example 12)
In the same manner as in Example 1 except that polycarbonate resin M300 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) is used instead of polycarbonate resin TS2050 (manufactured by Teijin Chemicals Co., Ltd.) in forming the surface-side charge transport layer. 12 electrophotographic photoreceptors were prepared.

(Comparative Example 1)
An electrophotographic photoreceptor of Comparative Example 1 was produced in the same manner as in Example 1 except that the charge transport layer was formed as a single layer instead of being formed as two layers. Specifically, it was produced as follows.

  First, in the same manner as in Example 1, an intermediate layer and a charge generation layer were sequentially formed on a conductive substrate. Subsequently, the exemplified compound No. 1 shown in Table 9 above as a charge transporting substance. 5 parts by weight of 61 enamine compound, 18 parts by weight of polycarbonate resin TS2050 (trade name, manufactured by Teijin Chemicals Ltd.) as the binder resin, and Sumilizer BHT (trade name, manufactured by Sumitomo Chemical Co., Ltd.) 0.05 as the antioxidant A charge transport layer coating solution was prepared using 47 parts by weight of tetrahydrofuran as a solvent. This coating solution was applied onto the previously formed charge generation layer by a dip coating method and heated at a temperature of 130 ° C. for 1 hour to form a charge transport layer having a layer thickness of 28 μm. As described above, an electrophotographic photosensitive member of Comparative Example 1 was produced.

(Comparative Examples 2 to 4)
When forming the charge transport layer, instead of polycarbonate resin TS2050 (manufactured by Teijin Chemicals Ltd.), polycarbonate resin G400 (trade name, manufactured by Idemitsu Kosan Co., Ltd.), polycarbonate resin M300 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) or polyester An electrophotographic photosensitive member was produced in the same manner as in Comparative Example 1 except that the resin Vylon 290 (trade name, manufactured by Toyobo Co., Ltd.) was used.

(Comparative Example 5)
In forming the charge generation layer side charge transport layer and the surface side charge transport layer, each of Exemplified Compound Nos. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that an enamine compound represented by the following structural formula (12) (hereinafter referred to as comparative compound A) was used in place of the 61 enamine compound. The comparative compound A corresponds to a compound in which the naphthylene group bonded to the nitrogen atom (N) constituting the enamine skeleton is substituted with another arylene group in the general formula (1).

(Comparative Example 6)
In forming the charge generation layer side charge transport layer and the surface side charge transport layer, each of Exemplified Compound Nos. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that an enamine compound represented by the following structural formula (13) (hereinafter referred to as comparative compound B) was used instead of 61 enamine compound. Comparative compound B corresponds to a compound in which n is 0 and Ar ³ is a group other than a heterocyclic group in general formula (1).

(Comparative Example 7)
In forming the charge generation layer side charge transport layer and the surface side charge transport layer, each of Exemplified Compound Nos. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that an enamine compound represented by the following structural formula (14) (hereinafter referred to as Comparative Compound C) was used instead of the 61 enamine compound. The comparative compound C corresponds to a compound obtained by substituting the naphthylene group bonded to the nitrogen atom (N) constituting the enamine skeleton with another arylene group in the general formula (1).

(Comparative Example 8)
In forming the charge generation layer side charge transport layer and the surface side charge transport layer, each of Exemplified Compound Nos. Instead of the 61 enamine compound, a triphenylamine dimer (abbreviated as TPD) represented by the following structural formula (15) was used, and a polycarbonate resin TS2050 (manufactured by Teijin Chemicals Ltd.) as a binder resin for the surface-side charge transport layer. ) Was used in the same manner as in Example 1 except that polycarbonate resin M300 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) was used. Hereinafter, TPD represented by Structural Formula (15) is referred to as Comparative Compound D.

(Comparative Example 9)
In the formation of the charge generation layer side charge transport layer and the surface side charge transport layer, each of Exemplified Compound Nos. A butadiene-based compound represented by the following structural formula (16) (hereinafter referred to as Comparative Compound E) is used in place of the 61 enamine compound, and polycarbonate resin TS2050 (Teijin Chemicals Ltd.) is used as a binder resin for the surface-side charge transport layer. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that polycarbonate resin M300 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) was used instead of (manufactured).

(Comparative Example 10)
In forming the charge generation layer side charge transport layer, polycarbonate resin TS2050 (manufactured by Teijin Chemicals Ltd.) is used instead of polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.), and in forming the surface side charge transport layer, polycarbonate resin TS2050 ( An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that polycarbonate resin M300 (manufactured by Idemitsu Kosan Co., Ltd.) was used instead of Teijin Chemicals Co., Ltd.

(Comparative Example 11)
In forming the charge generation layer side charge transport layer, a polyester resin Vylon 290 (manufactured by Toyobo Co., Ltd.) is used in place of the polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.), and in forming the surface side charge transport layer, the polycarbonate resin TS2050 ( An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.) was used instead of Teijin Chemicals Co., Ltd.

(Comparative Example 12)
In forming the charge generation layer side charge transport layer, polycarbonate resin TS2050 (manufactured by Teijin Chemicals Ltd.) is used instead of polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.), and in forming the surface side charge transport layer, polycarbonate resin TS2050 ( An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that polycarbonate resin G400 (manufactured by Idemitsu Kosan Co., Ltd.) was used instead of Teijin Chemicals Co., Ltd.

(Comparative Example 13)
In forming the charge generation layer side charge transport layer, the binder resin is replaced with 9 parts by weight of polycarbonate resin G400 (made by Idemitsu Kosan Co., Ltd.), two types of polycarbonate resins, G400 (made by Idemitsu Kosan Co., Ltd.), 5.4 weights. Part and TS2050 (manufactured by Teijin Chemicals Ltd.) were used in the same manner as in Example 1 except that 12.6 parts by weight were used.

(Comparative Example 14)
In forming the charge generation layer side charge transport layer, instead of 9 parts by weight of polycarbonate resin G400 (made by Idemitsu Kosan Co., Ltd.) as binder resin, two types of polycarbonate resins, 9 parts by weight of G400 (made by Idemitsu Kosan Co., Ltd.) and An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 9 parts by weight of M300 (manufactured by Idemitsu Kosan Co., Ltd.) was used.

As described above, in the preparation of each photoconductor of Examples 1 to 12 and Comparative Examples 1 to 14, the charge transport layer was changed by changing the type of the charge transport material and the type and amount of the binder resin for the charge transport layer. The elastic power η _{HU of} each layer constituting the layer was adjusted to a desired value. The elastic power η _HU of each layer was measured with a Fisherscope H100V (manufactured by Fisher Instruments Co., Ltd.) in an environment of a temperature of 25 ° C. and a relative humidity of 50%. The measurement conditions were an indentation maximum load W = 5 mN, a load required time to the indentation maximum load of 5 seconds, a load holding time t = 5 seconds, and an unloading time of 10 seconds.

[Evaluation]
Each of the photoreceptors of Examples 1 to 12 and Comparative Examples 1 to 14 is mounted on a test copying machine to form an image, whereby (a) printing durability and (b) low temperature and low humidity of each photoreceptor. The electrical properties and (c) cyclic stability of electrical properties under high temperature and high humidity were evaluated. For the test copying machine, a commercially available digital copying machine AR-450 (trade name, manufactured by Sharp Corporation) was used, and the photosensitive member rotation speed was 165.5 rotations per minute (rpm) for the test. A device in which the time until the end of development was modified to 60 milliseconds was used. Below, the evaluation method of each performance is demonstrated.

(A) Printing durability The pressure at which the cleaning blade of the cleaner provided in the test copying machine comes into contact with the photosensitive member, the so-called cleaning blade pressure, is adjusted to 21 gf / cm (2.06 × 10 ⁻¹ N / cm) as the initial linear pressure. did. Using this copier, a letter test chart made by Sharp Corporation is recorded on each photoconductor in a normal temperature / normal humidity (N / N) environment at a temperature of 25 ° C. and a relative humidity of 50%. A press life test for forming 100,000 sheets was performed.

  Before and after the printing test, the layer thickness of the photosensitive layer was measured using an instantaneous multi-photometry system MCPD-1100 (trade name, manufactured by Otsuka Electronics Co., Ltd.) based on the optical interference method. The film reduction amount Δd per 100,000 revolutions of the photoreceptor was determined from the difference from the layer thickness after image formation on 100,000 recording papers. It was evaluated that the printing durability was worse as the film reduction amount Δd was larger.

(B) Electrical characteristics under low temperature and low humidity The developing unit was removed from the test copying machine, and a surface potential meter (trade name: model 344, manufactured by Trek Japan Co., Ltd.) was provided instead at the development site. Using this copier, the surface potential of the photoreceptor after charging by the charger is minus (−) 650 V in a low temperature / low humidity (L / L) environment at a temperature of 5 ° C. and a relative humidity of 20%. It was adjusted to measure the surface potential of the photosensitive member when subjected to exposure by laser light in that state as an exposure potential VL (V), which was used as the exposure potential VL _L under the L / L environment. As the absolute value of the exposure potential VL _L is small, it was evaluated as excellent photoresponsive.

(C) Repetitive stability of electrical characteristics under high temperature and high humidity In a high temperature / high humidity (H / H) environment with a temperature of 35 ° C. and a relative humidity of 85%, the L / L environment of (b) The exposure potential VL (V) was measured in the same manner as the evaluation of the electrical characteristics below, and this was used as the initial exposure potential VL _H1 in the H / H environment. Further, in the H / H environment, using the above-described test copying machine, a character test original (manufactured by Sharp Corporation) having a printing rate of 5% was formed on 100,000 test sheets SF-4AM3 (manufactured by Sharp Corporation). Thereafter, the exposure potential VL (V) was measured in the same manner as in the initial stage, and this was used as the exposure potential VL _H2 after forming 100,000 images in an H / H environment. The absolute value (| VL _H2 −VL _H1 |) of the difference between the initial exposure potential VL _H1 in the H / H environment and the exposure potential VL _H2 after forming 100,000 images was determined as the potential fluctuation ΔVL. It was evaluated that the smaller the potential fluctuation ΔVL, the better the stability of electrical characteristics in repeated use under high temperature and high humidity.

The above evaluation results are shown in Table 33. In Table 33, for Comparative Examples 1 to 4 in which the charge transport layer is formed of one layer, the charge transport material used and the elastic work rate η _HU (%) are described in the column of the surface side charge transport layer.

In the evaluation of printing durability, the photoreceptors of Examples 1 to 12 and Comparative Examples 5 to 10 and 13 in which the elastic power η _HU of the surface-side charge transport layer is within the range of the present invention, that is, 47.0% or more, The film reduction amount Δd per 100,000 revolutions was as small as 0.51 to 0.95 μm, and the printing durability was excellent. Similarly, the photoreceptors of Comparative Examples 1 and 3 in which the elastic power η _{HU of} the single-layer charge transport layer is 47.0% or more have a small film reduction amount Δd per 100,000 revolutions, so that the printing durability is improved. Excellent results.

On the other hand, the elastic power η _HU of the surface-side charge transport layer is less than 47.0%, and Comparative Examples 11, 12, and 14 deviating from the scope of the present invention, and the elastic power η of the single-layer charge transport layer It can be seen that the photoconductors of Comparative Examples 2 and 4 with _HU of less than 47.0% have a large amount of film loss Δd per 100,000 revolutions, and there is a problem in achieving a long life.

Further, in the evaluation of the repetitive stability of the electrical characteristics in the H / H environment, Examples 1 to 12 in which the elastic power η _HU of the charge generation layer side charge transport layer is within the range of the present invention, that is, 46.0% or less. This photoreceptor has a small potential fluctuation ΔVL, and the residual potential does not increase even when it is repeatedly used in a high-temperature and high-humidity environment, indicating that stable sensitivity is obtained. On the other hand, the η _{HU of} the charge generation layer side charge transport layer exceeds 46.0% and falls outside the scope of the present invention, and the η _{HU of the} single charge transport layer is 46.0%. The photoconductors of Comparative Examples 1 and 3 having a large potential fluctuation ΔVL are inferior in stability of electrical characteristics in repeated use, and the sensitivity is lowered due to the formation of 100,000 images, resulting in a decrease in image density. It turns out that there is a problem with the use of

Further, in the electrical property evaluation under the L / L environment, the photoreceptors of Examples 1 to 12 using the enamine compound represented by the general formula (1) as the charge transport material are represented by the general formula (1). compared to Comparative example 5-9 using no enamine compounds, the absolute value of the exposure potential VL _L is small, the result having excellent photoresponsive was obtained. On the other hand, in the photoconductors of Comparative Examples 5 to 9, although both the surface-side charge transport layer and the charge generation layer-side charge transport layer have the elastic power η _HU within the scope of the present invention, Examples 1 to 12 the comparison with the photoconductor, the absolute value is very large in the exposure potential VL _L, it can be seen that not be obtained sufficient photoresponsive.

As described above, the charge transport layer is formed of two layers containing the enamine compound represented by the general formula (1) as the charge transport material, and the surface side charge transport provided on the surface side of the two layers. by the elastic work efficiency eta _HU layer is set more than 47.0%, to set the elastic work efficiency eta _HU charge generation layer side charge transport layer provided on the charge generation layer side below 46.0%, the surface An electrophotographic film that has excellent printing durability of the layer, does not deteriorate in sensitivity even when used repeatedly in harsh environments such as high-temperature and high-humidity environments, and has sufficient photoresponsiveness even in low-temperature and low-humidity environments. A photoconductor could be obtained.

1 is a partial cross-sectional view showing a simplified configuration of an electrophotographic photosensitive member 1 according to a first embodiment of the present invention. It is a figure explaining the method of calculating _| requiring the elastic work rate (eta) _HU of material. It is a fragmentary sectional view which simplifies and shows the structure of the electrophotographic photosensitive member 2 which is the 2nd Embodiment of this invention. It is a side view which simplifies and shows the structure of the image forming apparatus 30 which is the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Electrophotographic photoreceptor 11 Conductive substrate 12 Charge generation layer 13 Charge generation layer side charge transport layer 14 Surface side charge transport layer 15 Charge transport layer 16 Photosensitive layer 17 Intermediate layer

Claims (4)

An electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate,
The charge transport layer includes two layers of a charge generation layer side charge transport layer provided on the charge generation layer side and a surface side charge transport layer provided on the surface side facing outward,
The surface-side charge transport layer is
In an environment where the temperature is 25 ° C. and the relative humidity is 50%, the elastic work rate η _HU is 57.0% or more when the maximum indentation load of 5 mN is applied to the surface for 5 seconds, and is expressed by the following general formula (1). Containing enamine compounds
The charge generation layer side charge transport layer is
An electrophotographic photosensitive member comprising an enamine compound represented by the following general formula (1), wherein the elastic power η _HU is 46.0% or less.

(In the formula, Ar ¹ and Ar ² each represent an aryl group or a heterocyclic group which may have a substituent. Ar ³ represents an aryl group, a heterocyclic group or an aralkyl which may have a substituent. Each of Ar ⁴ and Ar ⁵ represents an aryl group, a heterocyclic group, an aralkyl group or an alkyl group, which may have a hydrogen atom or a substituent, provided that Ar ⁴ and Ar ⁵ At least one of them is a group other than a hydrogen atom, and a carbon atom to which the group = CAr ⁴ Ar ⁵ is bonded is bonded to a divalent aromatic ring group or heterocyclic group instead of the group = CAr ⁴ Ar ⁵ R ¹ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent, and R ² , R ³ and R ⁴ may each have a hydrogen atom or a substituent. , Archi Group, .n of an aryl group, a heterocyclic group or aralkyl group is an integer of 0 to 3. However, when n is 0, Ar ³ is a heterocyclic group which may have a substituent. The A plurality of R ² and R ³ may be the same or different when n is 2 or 3. R ⁵ is a hydrogen atom, a halogen atom or an alkyl group which may have a substituent, Represents an alkoxy group, a dialkylamino group or an aryl group, wherein l represents an integer of 1 to 6. However, when l is 2 or more, a plurality of R ^{5 s} may be the same or different; A divalent fused ring group may be formed together with the naphthylene group to be bonded.) The electrophotographic photoreceptor according to claim 1, wherein the enamine compound represented by the general formula (1) is an enamine compound represented by the following general formula (1a).

(In the formula, Ar ⁴ , Ar ⁵ , R ⁵ and l have the same definitions as in general formula (1). M represents 1 or 2. R ⁶ , R ⁷ and R ⁸ are each a hydrogen atom, a halogen atom, or a halogen atom. An alkyl group, an alkoxy group, a dialkylamino group or an aryl group, which may have an atom or a substituent, represents i, j and k each represent an integer of 1 to 5, provided that i, j or k is 2 In the above, a plurality of corresponding R ⁶ , R ⁷ or R ⁸ may be the same or different, and may form a monovalent fused ring group together with the phenyl group to which they are bonded. .) The electrophotographic photosensitive member according to claim 2, wherein the enamine compound represented by the general formula (1a) is an enamine compound represented by the following general formula (1b).

(In the formula, m has the same definition as in general formula (1a). R ^8a represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.) The electrophotographic photosensitive member according to any one of claims 1 to 3,
Charging means for charging the electrophotographic photosensitive member;
Exposure means for exposing a charged electrophotographic photosensitive member;
Developing means for developing an electrostatic latent image formed by exposure;
A transfer means for transferring a toner image formed on the surface of the electrophotographic photosensitive member by development to the transfer material from the surface;
An image forming apparatus comprising: a cleaning unit that cleans the surface of the electrophotographic photosensitive member after the toner image is transferred.

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