JP2015210477A - Electrophotographic photoreceptor, cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that reduces a surface potential and a residual potential at the initial stage and after repeated use of the electrophotographic photoreceptor to an exposure energy during writing of latent images and prevents the occurrence of image defects, and to provide a cartridge and an image forming apparatus.SOLUTION: There is provided an electrophotographic photoreceptor that has an undercoat layer and a photosensitive layer on a conductive support, where the undercoat layer contains an electron absorbing compound; the electron absorbing compound has a LUMO energy level of -2.50 to -3.20 eV and a polarizability of 27 to 43Å; and the photosensitive layer contains a polycarbonate resin.

Description

  The present invention relates to an electrophotographic photosensitive member, an image forming apparatus, and a cartridge used for a copying machine, a printer, and the like. More specifically, in an electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on a conductive support, a surface potential at the time of writing a latent image and a residual content can be obtained by containing a substance having a specific structure in the undercoat layer. The present invention relates to an electrophotographic photosensitive member, a cartridge, and an image forming apparatus that reduce potential and exhibit performance that is excellent in mechanical characteristics and electrical characteristics.

  The electrophotographic technique is widely used in the fields of copiers, various printers, printing presses and the like because of its excellent immediacy and high quality images. As an electrophotographic photosensitive member that is the core of the electrophotographic technology, an electrophotographic photosensitive member using an organic photoconductive material having advantages such as non-pollution, easy film formation, and easy manufacture (hereinafter simply referred to as “ Also referred to as “photoreceptor”).

  As an electrophotographic photoreceptor using an organic photoconductive material, a so-called dispersion type single-layer photoreceptor in which a photoconductive fine powder is dispersed in a binder resin, or a charge generation layer on a conductive support substrate. In addition, a multilayer photoreceptor in which a charge transport layer is laminated is known. In an electrophotographic photosensitive member in which a photosensitive layer is directly coated on a conductive support substrate, charges may be injected into the photosensitive layer because the conductive support substrate and the photosensitive layer are close to each other, and microscopic surface charge disappears or decreases. May cause image defects. In order to prevent such image defects, in order to prevent charge injection from the conductive support substrate, conceal defects on the surface of the conductive support substrate, improve the adhesion between the photosensitive layer and the substrate, etc., An undercoat layer is provided between the layers (Patent Document 1).

  Electrophotographic image forming apparatuses are becoming higher in image quality, faster and more durable year by year. In particular, further improvement is demanded on the electrophotographic photosensitive member side for higher image quality. On the other hand, electrophotographic photoreceptors are continuously required to be high performance and inexpensive. As one of the techniques that satisfy such a requirement, a method is known in which an undercoat layer is introduced on an inexpensive conductive substrate to stabilize electrical characteristics and image characteristics.

  For example, in order to avoid optical interference caused by roughness of the surface of the conductive support and image defects caused by defects on the surface of the substrate, techniques for introducing an undercoat layer are disclosed (Patent Documents 2 and 3). . Focusing on the undercoat layer, there is a technique of using a specific compound for the undercoat layer in order to improve the function of the electrophotographic photosensitive member. For example, a technique for improving the environmental characteristics and image characteristics of an electrophotographic photoreceptor by containing various electron transporting organic compounds in the undercoat layer is disclosed (Patent Documents 4-6). Furthermore, an electrophotographic photosensitive member is disclosed in which a reactive electron-withdrawing compound containing an anthraquinone structure is contained in the undercoat layer so that the image formation history of the previous cycle hardly remains in the next cycle (Patent Document 7). On the other hand, there is known a technique for improving the durability of an electrophotographic photosensitive member by using a compound such as a cyano-containing phenol derivative or a sulfonic acid ester derivative in the photosensitive layer of the electrophotographic photosensitive member (Patent Documents 8 and 9). There is no disclosure of use for the undercoat layer. Due to the difference in function between the photosensitive layer and the undercoat layer, if the layer containing a specific compound is different, the effect of containing the compound is also different.

Japanese Patent Laid-Open No. 2000-24216 JP 2001-100595 A JP 2002-287395 A JP 2002-091044 A Japanese Unexamined Patent Application Publication No. 2004-093792 JP 2010-127963 A JP 2013-200417 A JP 58-54346 A JP-A-3-48852

  When the electrophotographic photosensitive member has an undercoat layer, the influence of the conductive substrate can be alleviated, but there is a problem that the residual potential increases. In addition, when a compound is contained in the undercoat layer in order to suppress an increase in the residual potential, even if the initial residual potential increase can be suppressed, the electrical characteristics after use in the repetitive process deteriorate, or the repetitive process When used, the electrical characteristics are stabilized, but there is a problem that the initial residual potential increases. It is made in view of the above-mentioned subject. That is, the object of the present invention is to reduce the surface potential of the electrophotographic photosensitive member at the initial stage and after repeated use, and the residual potential with respect to the exposure energy at the time of writing a latent image in the case of having an undercoat layer, and does not cause image defects. An electrophotographic photosensitive member is provided, and a cartridge and an image forming apparatus are provided.

In the electrophotographic photosensitive member, the electrophotographic photosensitive member contains an electron-withdrawing compound having a specific LUMO energy level and a polarizability range in the undercoat layer, so that the photosensitive member surface potential with respect to the exposure energy at the time of writing a latent image. It has been found that a good effect in terms of electrical characteristics such as reduction of residual potential can be obtained. That is, the gist of the present invention resides in the following five points.
<1> An electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer contains an electron-withdrawing compound, and the LUMO energy level of the electron-withdrawing compound is An electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has −2.50 to −3.20 eV, a polarizability of 27 to 43 × ³ , and the photosensitive layer contains a polycarbonate resin.
<2> The electrophotographic photosensitive member according to <1>, wherein the content of the electron withdrawing compound in the undercoat layer is 0.25 to 20% by mass with respect to the total mass of the undercoat layer.
<3> The electrophotographic photosensitive member according to <1> or <2>, wherein the undercoat layer contains metal oxide particles.
<4> The electrophotographic photosensitive member according to <3>, wherein the metal oxide particles are titanium oxide or aluminum oxide.
<5> The electrophotographic photosensitive member according to any one of <1> to <4>, wherein the charge generation layer contains oxytitanium phthalocyanine.

  According to the present invention, it is possible to provide an electrophotographic photoconductor that does not cause image defects by reducing the surface potential and the residual potential of the electrophotographic photoconductor at the initial stage and after repeated use with respect to the exposure energy at the time of writing a latent image. .

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus according to the present invention. It is a chart figure which shows the CuKalpha characteristic X-ray-diffraction peak of the titanyl phthalocyanine pigment used in an Example.

Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following descriptions, and can be appropriately modified and implemented without departing from the gist of the present invention.

[Electrophotographic photoreceptor]
The present invention is an electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on a conductive support. Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail.

<Conductive support>
As the conductive support used for the photoreceptor, for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powders such as metal, carbon, and tin oxide are added to impart conductivity. A resin material, a resin, glass, paper, or the like on which a conductive material such as aluminum, nickel, or ITO (indium tin oxide) is deposited or applied on the surface is mainly used. As a form, a drum shape, a sheet shape, a belt shape or the like is used. A conductive material having an appropriate resistance value may be applied to a conductive support of a metal material in order to control conductivity, surface properties, etc., or to cover defects.

When a metal material such as an aluminum alloy is used as the conductive support, it may be used after an anodized film is applied. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
The support surface may be smooth, or may be roughened by using a special cutting method or polishing. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support. In order to reduce the cost, it is possible to use the drawing tube as it is without cutting. In particular, when using a non-cutting aluminum substrate such as drawing, impact processing, ironing, etc., it is preferable because the treatment eliminates dirt, foreign matter, and other foreign matters, small scratches, etc., and a uniform and clean substrate can be obtained. .

<Underlayer>
An undercoat layer is provided between the conductive support and a photosensitive layer described later. The undercoat layer contains an electron-withdrawing compound having a LUMO energy level of −2.50 to −3.20 eV and a polarizability of 27 to 43 ^{3 3} . Moreover, it is preferable to contain binder resin for ensuring strength. The undercoat layer may have a plurality of layers, and in the case of having a plurality of layers, from the viewpoint of suppressing the generation of a ghost image while maintaining the electrical blocking function, the undercoat layer has a conductive layer and a blocking layer. A layer-type undercoat layer is preferred. In this case, the conductive layer contains carbon black, conductive particles such as metal particles and metal oxide particles, and a binder resin, and the blocking layer moves charges having the same polarity as the charge charged on the surface of the photoreceptor. It is preferable to contain what has the function which can be performed, and binder resin. From the viewpoint of residual potential due to thickening, a single layer type undercoat layer having both functions of conductivity and blocking is preferable. The thickness of the undercoat layer is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm, from the viewpoints of the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and leakage due to foreign matter of the electrophotographic photoreceptor. Above, more preferably 15 μm or more, particularly preferably 20 μm or more. Moreover, it is 30 micrometers or less normally, Preferably it is 25 micrometers or less. A known antioxidant or the like may be mixed in the undercoat layer. The undercoat layer may contain pigment particles, resin particles, and the like for the purpose of preventing image defects.

[Electron-withdrawing compound]
The electron withdrawing compound of the present invention has a LUMO energy level of −2.50 to −3.20 eV and a polarizability of 27 to 43 ^{3 3} . The LUMO energy level and the polarizability can be calculated by structure optimization calculation using B3LYP / 6-31G (d, p) (see JP 2011-170041). The LUMO energy level is preferably −2.60 eV or less, more preferably −2.70 eV or less, from the viewpoint of electron transfer from the charge generation layer. On the other hand, from the viewpoint of chargeability of the electrophotographic photosensitive member, −3
. 00 eV or more is preferable, and -2.90 eV or more is more preferable. The polarizability is preferably 28 ³ or more, more preferably 30 ³ or more, from the viewpoint of the interaction between molecules. On the other hand, from the viewpoint of molecular stability, it is preferably 42 ³ or less, and more preferably 40 ³ or less.

An electron-withdrawing compound satisfying both the LUMO energy level of −2.50 to −3.20 eV and the polarizability of 27 to 43 ³ indicates that it is a compound that is easy to accept electrons and has high solubility. In this range, the surface potential and residual potential of the electrophotographic photosensitive member relative to the exposure energy at the time of writing a latent image and the residual potential are reduced. be able to.

  Specific examples of the structure of the electron-withdrawing compound are shown below. These specific examples are shown for illustrative purposes and are not limited to these embodiments.

  Among these, it is preferable that it is a compound represented by General formula (1) from a viewpoint of an electrical property.

(In the general formula (1), X represents —OSO ₂ Ar ¹ or —OCOAr ^2. A represents a phenyl group, a naphthyl group, or an anthracenyl group. Ar ¹ and Ar ² represent a cyano group and an alkyl group. , A hydroxyl group, a phenyl group which may have a halogen atom, and n represents 0-3.)

Specifically, as the alkyl group, a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group or an n-butyl group, a branched alkyl group such as an isopropyl group or an ethylhexyl group, or a cyclic group such as a cyclohexyl group. An alkyl group is mentioned. Among these, a C1-C20 alkyl group is preferable from the versatility of a manufacturing raw material, and a C1-C12 alkyl group is more preferable from the surface of the handleability at the time of manufacture, and light attenuation as an electrophotographic photoreceptor From the viewpoint of characteristics, an alkyl group having 1 to 6 carbon atoms is more preferable. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. Among these, a chlorine atom is preferable from the viewpoint of residual potential. From the viewpoint of reducing the residual potential, X is preferably —OSO ₂ Ar ¹ , and Ar ¹ is preferably a phenyl group having a chlorine atom. n is preferably 0 to 2 from the viewpoint of reducing the residual potential. When A is a phenyl group, the substitution position of X is preferably the ortho-position or para-position from the viewpoint of ease of production, and more preferably para-position from the viewpoint of reducing residual potential. Specific examples of suitable structures are shown below. These specific examples are shown for illustrative purposes and are not limited to these embodiments.

In the undercoat layer, the electron-withdrawing compound is usually used at 0.25% by mass or more based on the total mass of the undercoat layer. From the viewpoint of stability when used repeatedly, the content is preferably 5% by mass or more. On the other hand, the electron withdrawing compound is usually used in an amount of 20% by mass or less based on the total mass of the undercoat layer. It is preferable that it is 15 mass% or less from a compatible viewpoint of an electron withdrawing compound and binder resin. Moreover, the ratio of binder resin and an electron withdrawing compound uses an electron withdrawing compound in the ratio of 1 mass part or more with respect to 100 mass parts of binder resin from a viewpoint of residual potential reduction. Among these, 5 parts by mass or more is preferable from the viewpoint of stability when repeatedly used, and 8 parts by mass or more is more preferable from the viewpoint of electron mobility. On the other hand, from the viewpoint of the film strength of the undercoat layer, the electron withdrawing compound is usually used at a ratio of 100 parts by mass or less. Among these, 80 parts by mass or less is preferable from the viewpoint of compatibility between the electron-withdrawing compound and the binder resin, 50 parts by mass or less is more preferable from the viewpoint of leakage resistance, and 30 parts by mass or less is more preferable from the viewpoint of memory.

[Metal oxide particles]
The undercoat layer preferably contains metal oxide particles from the viewpoint of residual potential. Examples of the metal oxide particles include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, strontium titanate, titanate. Examples thereof include metal oxide particles containing a plurality of metal elements such as barium. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable from the viewpoint of concealing power which is effective to have a material having a high refractive index and prevents the generation of moire images. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicone. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of a several crystal state may be contained.

  In addition, various particle sizes of the metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is usually 1 nm or more, preferably 10 nm or more, and usually 100 nm or less. Preferably it is 50 nm or less. The use ratio of the inorganic particles to the binder resin is usually preferably in the range of 10% by mass or more and 500% by mass or less from the viewpoint of the stability of the dispersion and the coating property.

[Binder resin]
As binder resin used for the undercoat layer, epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, Known binder resins such as polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacrylic acid resin and the like can be mentioned. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Of these, polyamide resins such as alcohol-soluble copolymerized polyamides and modified polyamides are preferable because they exhibit good dispersibility and coating properties.

As the thermosetting resin, a mixture of alkyd / melamine resin is particularly preferably used. At this time, the mixing ratio of the alkyd / melamine resin is an important factor for determining the structure and characteristics of the undercoat layer. A range where the ratio (mass ratio) of the two is 5/5 to 8/2 is a good range of the mixing ratio. When the amount of melamine resin is less than 5/5, volume shrinkage does not increase during thermosetting, and coating film defects are less likely to occur, and the residual potential of the photoreceptor is reduced. Further, when the amount of alkyd resin is less than 8/2, the bulk resistance is not too low, and the soiling becomes good, which is preferable.
The number average molecular weight of the binder resin is usually 5000 or more, preferably 6000 or more, more preferably 8000 or more from the viewpoint of coatability. From the viewpoint of compatibility with the benzalmalononitrile compound, it is usually 200000 or less, preferably 100,000 or less, and more preferably 70000 or less from the viewpoint of residual potential.

<Photosensitive layer>
The photoreceptor of the present invention has a photosensitive layer on a conductive support. The photosensitive layer contains a polycarbonate resin. The photoreceptor of the present invention includes a laminate type photoreceptor having a laminate type photosensitive layer including a charge generation layer (a layer containing a charge generation material) and a charge transport layer (a layer containing a charge transport material), or a charge generation material and a charge. There is a single-layer type photoreceptor containing a transport material in the same photosensitive layer.

<Laminated photosensitive layer>
(Charge generation layer)
The charge generation layer of the laminated photosensitive layer (function-separated type photosensitive layer) contains a charge generation material and usually contains a binder resin and other components used as necessary. Such a charge generation layer is prepared, for example, by dissolving or dispersing a charge generation material and a binder resin in a solvent or dispersion medium to prepare a coating solution, and in the case of a sequentially laminated photosensitive layer, this is formed on a conductive support. (If an undercoat layer is provided, it can be obtained on the undercoat layer). In the case of a reverse laminated type photosensitive layer, it can be obtained by coating on a charge transport layer and drying. The film thickness of the charge generation layer is not particularly limited, but is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 1 μm or less, preferably 0.6 μm or less.

  Examples of charge generation materials include selenium and its alloys, cadmium sulfide, and other inorganic photoconductive materials; phthalocyanine pigments, azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, benzimidazole pigments Various photoconductive materials such as organic pigments; In particular, organic pigments are preferable, and phthalocyanine pigments and azo pigments are particularly preferable. Note that one type of charge generation material may be used, or two or more types may be used in any combination and in any ratio.

  In particular, when a phthalocyanine compound is used as the charge generating substance, specific examples thereof include metal-free phthalocyanine; metals such as copper, indium, gallium, tin, titanium, zinc, vanadium, silicone, germanium, or oxides thereof, halides, and the like. Phthalocyanines coordinated with, and the like. Examples of the ligand to the metal atom having 3 or more valences include a hydroxyl group and an alkoxy group in addition to the oxygen atom and chlorine atom shown above. Particularly preferred are X-type, τ-type metal-free phthalocyanine, titanyl phthalocyanine such as A-type, B-type, and D-type, vanadyl phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine. Of the crystal forms of titanyl phthalocyanine mentioned here, A type and B type are described in W.W. Heller et al. Have shown them as phase I and phase II (Zeit. Kristallogr. 159 (1982) 173), respectively, and the A type is also called the β type and is known as the stable type. D-type is a metastable type, also called Y-type, and is a crystal type characterized by a clear peak at a diffraction angle 2θ ± 0.2 ° of 27.3 ° in powder X-ray diffraction using CuKα rays. is there.

  As the phthalocyanine compound, only a single compound may be used, or several mixed states may be used. As the mixed state in the phthalocyanine compound or the crystalline state here, the respective constituent elements may be mixed and used later, or a mixed state is generated in the production and processing steps of the phthalocyanine compound such as synthesis, pigmentation, and crystallization. It can be stuffed. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known.

These charge generation materials usually have fine particles such as polyester resin, polyvinyl acetate resin, polyacrylate resin, polymethacrylate resin, polyester resin, polycarbonate resin, polyvinyl acetoacetal resin, polyvinyl propional resin, polyvinyl butyral. It is used in a form bound with various binder resins such as resin, phenoxy resin, epoxy resin, urethane resin, cellulose ester, and cellulose ether. In this case, the polyester resin according to the present invention may be used as the binder resin. Moreover, 1 type may be used for binder resin and it may use 2 or more types together by arbitrary combinations and arbitrary ratios.
The use ratio of the charge generation material in the charge generation layer is usually 30 parts by mass or more, preferably 50 parts by mass or more, and usually 500 parts by mass or less, preferably 300 parts by mass or less with respect to 100 parts by mass of the binder resin. .

(Charge transport layer)
The charge transport layer of the multilayer photoreceptor contains a charge transport material, a binder resin, and other components used as necessary. The binder resin is preferably a polycarbonate resin. Specifically, such a charge transport layer is prepared by dissolving or dispersing a charge transport material or the like and a binder resin in a solvent to prepare a coating solution. In addition, in the case of a reverse lamination type photosensitive layer, it can be obtained by coating on an undercoat layer and drying. The film thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, on the other hand, usually 50 μm or less, preferably 45 μm or less, from the viewpoints of long life, image stability, and charging stability. Furthermore, in the range of 40 μm or less, 35 μm or less is particularly preferably used from the viewpoint of increasing the resolution.

  As the charge transporting material, other known charge transporting materials can be used, and the kind thereof is not particularly limited. What was combined two or more is preferable. Specific examples of suitable structures of the charge transport material are shown below. These specific examples are shown for illustration, and any known charge transport material may be used as long as it is not contrary to the gist of the present invention.

  Binder resins include butadiene resins, styrene resins, vinyl acetate resins, vinyl chloride resins, acrylic ester resins, methacrylic ester resins, vinyl alcohol resins, polymers of vinyl compounds such as ethyl vinyl ether, copolymers, and polyvinyl butyral resins. Polyvinyl formal resin, partially modified polyvinyl acetal, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicone resin, silicone-alkyd resin, poly-N-vinylcarbazole resin, polycarbonate resin, polyester resin are preferably used. . Of these, polycarbonate resins and polyarylate resins are preferred. From the viewpoint of maintaining electrical characteristics, a polycarbonate resin is particularly preferable.

  Specific examples of suitable structures of the binder resin are shown below. These specific examples are shown for illustration, and any known binder resin may be used as long as it does not contradict the gist of the present invention.

The viscosity average molecular weight of the binder resin used for the charge transport layer is arbitrary as long as the effects of the present invention are not significantly impaired. From the viewpoint of strength, the lower limit is usually 20,000 or more, preferably 30,000 or more, more preferably. Is over 50,000. From the viewpoint of applicability,
The upper limit is usually 150,000 or less, preferably 100,000 or less, more preferably 90,000 or less.

  As for the ratio of the binder resin to the charge transport material, the charge transport material is usually used at a ratio of 10 parts by mass or more with respect to 100 parts by mass of the binder resin. Among these, 20 parts by mass or more is preferable from the viewpoint of residual potential reduction, and more preferably 30 parts by mass or more from the viewpoint of stability and charge mobility when repeatedly used. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, the charge transport material is usually used at a ratio of 120 parts by mass or less. Among these, 100 parts by mass or less is preferable from the viewpoint of compatibility between the charge transport material and the binder resin, 70 parts by mass or less is more preferable from the viewpoint of printing durability, and 50 parts by mass or less is particularly preferable from the viewpoint of scratch resistance.

<Single layer type photosensitive layer>
In addition to the charge generation material and the charge transport material, the single-layer type photosensitive layer is formed using a polycarbonate resin in order to ensure film strength, in the same manner as the charge transport layer of the multilayer photoreceptor. Specifically, the charge generation material, the charge transport material, and the polycarbonate resin can be dissolved or dispersed in a solvent to prepare a coating solution, which can be applied on the undercoat layer and dried. The film thickness of the single-layer type photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less.

The types of the charge transport material and the binder resin, and the usage ratios thereof are the same as those described for the charge transport layer of the multilayer photoreceptor. A charge generating substance is further dispersed in a charge transport medium comprising these charge transport material and binder resin.
As the charge generation material, the same materials as those described for the charge generation layer of the multilayer photoreceptor can be used. However, in the case of a photosensitive layer of a single layer type photoreceptor, it is necessary to sufficiently reduce the particle size of the charge generating material. Specifically, the range is usually 1 μm or less, preferably 0.5 μm or less.
In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. It is 30 mass parts or less, Preferably it is set as the range of 10 mass parts or less.

<Other functional layers>
For the purpose of improving film-forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, etc., in both the photosensitive layer and each layer constituting it, both in the multilayer type photosensitive member and the single layer type photosensitive member. Additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents may be included.
Further, in both the laminated type photoreceptor and the single layer type photoreceptor, the photosensitive layer formed by the above procedure may be the uppermost layer, that is, the surface layer, but another layer may be provided on the photosensitive layer and used as the surface layer. Good. For example, a protective layer may be provided for the purpose of preventing wear of the photosensitive layer or preventing or reducing deterioration of the photosensitive layer due to discharge products generated from a charger or the like.

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

[Cartridge, image forming device]
Next, a drum cartridge and an image forming apparatus using the electrophotographic photosensitive member of the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes a drum-shaped photoconductor, which is rotationally driven at a predetermined peripheral speed in the direction of an arrow. The photosensitive member 1 is uniformly charged at a predetermined positive or negative potential on the surface thereof by the charging unit 2 during the rotation process, and then exposure for forming a latent image is performed by the image exposure unit in the exposure unit 3.

The formed electrostatic latent image is then developed with toner by the developing means 4, and the toner developed image is sequentially transferred onto the transfer body (paper or the like) P fed from the paper feeding unit by the corona transfer means 5. . In FIG. 1, the developing unit 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing unit 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

  The image-transferred transfer body is then sent to the fixing means 7 where the image is fixed and printed out of the apparatus. The fixing unit 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. The upper and lower fixing members 71 and 72 include a fixing roll in which a metal base tube made of stainless steel, aluminum or the like is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, a fixing sheet, or the like. A member can be used. Further, the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve the releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

  When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P. The surface of the photoreceptor 1 after the image transfer is cleaned by the cleaning unit 6 to remove the transfer residual toner, and is neutralized by the neutralization unit for the next image formation.

  In using the electrophotographic photosensitive member of the present invention, as a charger, in addition to a corona charger such as corotron or scorotron, a direct charging means for charging a charged member by contacting a directly charged member to which a voltage is applied is provided. It may be used. Examples of direct charging means include contact chargers such as charging rollers and charging brushes. As the direct charging means, any one that involves air discharge or injection charging that does not involve air discharge is possible. In addition, as a voltage applied at the time of charging, in the case of only a direct current voltage, an alternating current can be superimposed on a direct current.

For the exposure, a halogen lamp, a fluorescent lamp, a laser (semiconductor, He—Ne), LED, a photoreceptor internal exposure system, or the like is used. As a digital electrophotographic system, it is preferable to use a laser, an LED, an optical shutter array, or the like. . As the wavelength, in addition to 780 nm monochromatic light, it is possible to use monochromatic light in the 600 to 700 nm region and slightly shorter wavelength.
In the development process, a dry development method such as cascade development, one-component insulating toner development, one-component conductive toner development, two-component magnetic brush development, or the like is used.

  As the toner, in addition to the pulverized toner, chemical toners such as suspension granulation, suspension polymerization, and emulsion polymerization aggregation can be used. In particular, in the case of chemical toners, those having a small particle diameter of about 4 to 8 μm are used, and those having a shape close to a sphere, and those outside a potato-like sphere can also be used. The polymerized toner is excellent in charging uniformity and transferability, and is preferably used for high image quality.

For the transfer process, electrostatic transfer methods such as corona transfer, roller transfer, and belt transfer, pressure transfer methods, and adhesive transfer methods are used. For fixing, heat roller fixing, flash fixing, oven fixing, pressure fixing, IH fixing, belt fixing, IHF fixing, etc. may be used. These fixing methods may be used alone or in combination with a plurality of fixing methods. May be.
For cleaning, brush cleaner, magnetic brush cleaner, electrostatic brush cleaner, magnetic roller cleaner, blade cleaner, etc. are used.

In many cases, the static elimination step is omitted, but when used, a fluorescent lamp, LED, or the like is used, and an exposure energy that is three times or more of the exposure light is often used as the intensity. In addition to these processes, a pre-exposure process and an auxiliary charging process may be included.
A cartridge using the electrophotographic photosensitive member according to the present invention includes the photosensitive member 1 and at least one portion of the group consisting of the charging unit 2, the exposure unit 3, the developing unit 4, and the cleaning unit 6. Good.

In the present invention, a plurality of components such as the drum-shaped photosensitive member 1, the charging unit 2, the developing unit 4 and the cleaning unit 6 are integrally combined as a drum cartridge, and the drum cartridge is copied. It may be configured to be detachable from the main body of an electrophotographic apparatus such as a machine or a laser beam printer. For example, at least one of the charging unit 2, the developing unit 4, and the cleaning unit 6 can be integrally supported together with the drum-shaped photoreceptor 1 to form a cartridge.
The present invention can also be applied to an image forming apparatus including the electrophotographic photosensitive member, the charging unit 2, the exposure unit 3, the developing unit 4, and the cleaning unit 6 according to the present invention.

  Hereinafter, the present invention will be described in more detail with reference to production examples, examples and comparative examples. In addition, the following examples are shown in order to explain the present invention in detail, and the present invention is not limited to the following examples unless it is contrary to the gist thereof.

  <LUMO and polarizability of compounds used in Examples and Comparative Examples>

<Preparation of dispersion for undercoat layer>
(Preparation Example 1)
The undercoat layer dispersion was produced as follows. That is, a rutile type titanium oxide having an average primary particle size of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by mass of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were flowed at high speed. In a mixed solvent of methanol / 1-propanol in a mixed solvent of methanol / 1-propanol, which was introduced into a mixing kneader (“SMG300” manufactured by Kawata Co., Ltd.) and mixed at a high rotational speed of 34.5 m / sec. Then, a dispersion slurry of hydrophobized titanium oxide was obtained by dispersing with a ball mill. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam / bis (4-amino-3-methylcyclohexyl) methane / hexamethylenediamine / decamethylenedicarboxylic acid / octadecamethylenedicarboxylic acid Heating a copolyamide pellet having a composition molar ratio of 60% / 15% / 5% / 15% / 5% and an electron withdrawing compound (A-1) corresponding to a 10% mass ratio of the polyamide resin While stirring and mixing, the polyamide pellets are dissolved, and then subjected to ultrasonic dispersion treatment, so that the mass ratio of methanol / 1-propanol / toluene is 7/1/2, and hydrophobically treated titanium oxide / copolymerization. An undercoat layer dispersion containing a polyamide in a mass ratio of 3/1 and having a solid content concentration of 18.0% was obtained.

(Preparation example 2)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-2) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.
(Preparation example 3)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-3) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.

(Preparation example 4)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-4) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.
(Preparation example 5)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-5) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.

(Comparison preparation example 1)
A dispersion for undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron-withdrawing compound (A-1) was not used in Preparation Example 1.
(Comparison preparation example 2)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-6) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.

(Comparison preparation example 3)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-7) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.
(Comparison preparation example 4)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-8) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.

(Comparison preparation example 5)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-9) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.
(Comparison preparation example 6)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-10) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.

(Comparison preparation example 7)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-11) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.
(Comparison preparation example 8)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-12) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.

(Comparison preparation example 9)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-13) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.
(Comparative preparation example 10)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-14) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.

(Comparative Preparation Example 11)
The dispersion for the undercoat layer was prepared in the same manner as in Preparation Example 1 except that the electron withdrawing compound (A-15) was used instead of the electron withdrawing compound (A-1) in Preparation Example 1. Prepared.

<Photosensitive sheet preparation method>
[Example 1]
Apply the coating solution for forming the undercoat layer obtained in Preparation Example 1 on a polyethylene terephthalate sheet (thickness 75 μm) with aluminum deposited on the surface so that the film thickness after drying is 1.2 μm. And dried to provide an undercoat layer.

Next, the Bragg angle (2θ ± 0. 0) in X-ray diffraction by CuKα rays obtained by making it amorphous by mechanical treatment by the same method as in Comparative Synthesis Example 1 of JP-A-2007-148387 was obtained. 2) showed a strong diffraction peak at 27.3 ° (D-type), 10 parts by mass of oxytitanium phthalocyanine having the powder X-ray diffraction spectrum shown in FIG. 2 was added to 150 parts by mass of 1,2-dimethoxyethane, A pulverization dispersion treatment was performed with a mill to prepare a pigment dispersion. 160 parts by mass of the pigment dispersion thus obtained was added to 100 parts by mass of a 5% 1,2-dimethoxyethane solution of polyvinyl butyral (trade name # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.), and an appropriate amount of 1,2 -Dimethoxyethane is added and finally the solids concentration is 4.0
A coating solution for forming a mass% charge generation layer was prepared. This charge generation layer forming coating solution was applied on the above-described undercoat layer with a wire bar so that the film thickness after drying was 0.4 μm, and then dried to form a charge generation layer.

Next, 50 parts by mass of CTM-1 represented by the following structural formula as a charge transport material, 8 parts by mass of an antioxidant (1) represented by the following formula as an antioxidant, and a polycarbonate having the following repeating structure as a binder resin Resin (PCR-A, viscosity average molecular weight 40,000) 100 parts by mass, silicone oil 0.1 parts by mass as a leveling agent, mixed solvent of tetrahydrofuran and toluene (tetrahydrofuran 80 mass%, toluene 20 mass%) 640 mass The coating solution for forming a charge transport layer was prepared by mixing with the part.

[Examples 2 to 5]
In the same manner as in Example 1 except that the undercoat layer forming coating solution of Preparation Examples 2 to 5 was used instead of the undercoat layer forming coating solution of Preparation Example 1 used in Example 1, A photoconductor sheet sample was prepared.

[Comparative Example 1]
In the same manner as in Example 1, except that the undercoat layer forming coating solution of Comparative Preparation Example 1 was used instead of the undercoat layer forming coating solution of Preparation Example 1 used in Example 1, electrophotography A photoreceptor sheet sample was prepared.

[Comparative Examples 2 to 11]
Instead of the coating solution for forming the undercoat layer of Preparation Example 1 used in Example 1, the coating solution for forming the undercoat layer of Comparative Preparation Examples 2 to 9 was used in the same manner as in Example 1, An electrophotographic photoreceptor sheet sample was prepared.

<Evaluation of electrical characteristics of photoconductor>
Using an electrophotographic characteristic evaluation apparatus (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404-405) prepared according to the Electrophotographic Society measurement standard, the photoconductor is made into an aluminum drum. Attached to a cylindrical shape, the aluminum drum and the aluminum base of the photoconductor are connected, and then the drum is rotated at a constant rotational speed, and an electrical property evaluation test is performed by a cycle of charging, exposure, potential measurement, and static elimination. went.

At that time, the initial surface potential was −700 V, exposure was 780 nm, and charge removal was monochromatic light of 660 nm. As the surface potential (VL) when 780 nm light was irradiated at 1.0 μJ / cm ² and the index representing sensitivity, the exposure amount (half exposure amount) required to halve the surface potential to −350 V was measured. In the VL measurement, the time required for the exposure-potential measurement was 100 ms. The measurement environment was a temperature of 35 ° C. and a relative humidity of 85%, and the measurement was performed after repeating the initial and 5000 times. The results of electrical characteristics are shown in Table-5. The difference between the initial VL and the VL after 5000 iterations was taken as ΔVL. The smaller this value, the better the repetition characteristics.

As can be seen from the results of Table-5 above, the inclusion of an electron withdrawing compound within the scope of the present invention in the undercoat layer results in nothing added or repeated characteristics compared to compounds outside the scope of the present invention. Is good. In Comparative Example 4, Comparative Example 6, Comparative Example 7, and Comparative Example 10, the value of ΔVL is smaller than that of the example, but the initial value of VL is large. By using the configuration of the present embodiment for the undercoat layer, it is considered that the movement of electrons from the charge generation layer to the undercoat layer is accelerated, the internal residual charge is reduced, and this leads to the effect of reducing the surface potential VL.

Claims (5)

An electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer contains an electron-withdrawing compound, and the LUMO energy level of the electron-withdrawing compound is -2. An electrophotographic photoreceptor, wherein the electrophotographic photoreceptor has a 50 to -3.20 eV and a polarizability of 27 to 43 ³ , and the photosensitive layer contains a polycarbonate resin.   The electrophotographic photosensitive member according to claim 1, wherein the content of the electron-withdrawing compound in the undercoat layer is 0.25 to 20% by mass with respect to the total mass of the undercoat layer.   The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer contains metal oxide particles.   The electrophotographic photosensitive member according to claim 3, wherein the metal oxide particles are titanium oxide or aluminum oxide.   The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the charge generation layer contains oxytitanium phthalocyanine.

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