JP6015187B2 - Electrophotographic photosensitive member for liquid development and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member used for a copying machine, a printer, and the like. More particularly, the present invention relates to an electrophotographic photosensitive member for liquid development having excellent solvent resistance and good electrical characteristics, an image forming apparatus and an image forming method of a liquid development system.

  In the electrophotographic technology, the development process methods for visualizing an image are roughly classified into a dry development method and a liquid (wet) development method. Among these, the liquid development method has a long history that originated in the 1950s, but there are problems for office use, such as using a developing solvent (usually an organic solvent). Generally, dry development is exclusively used for office use. The system is currently used. However, a toner with a small diameter of 0.1 μm to 2 μm can be used, higher resolution than dry type, high image quality close to that of offset printing can be obtained, and high speed can be supported. It is increasingly used in place of offset printing for new commercial printing systems such as demand printing.

  On the other hand, an electrophotographic photoreceptor (hereinafter referred to as “photoreceptor” as appropriate) which is the core of the electrophotographic technology has advantages such as pollution-free and easy film formation, easy production and low cost. Photoconductors using organic photoconductive materials are the mainstream. Examples of the photoreceptor using the organic photoconductive material (organic photoreceptor) include, for example, a so-called dispersed photoreceptor (single-layer photoreceptor) in which photoconductive fine powder is dispersed in a binder resin, and charge generation layer. In addition, a laminate type photoreceptor (function separation type photoreceptor) in which a charge transport layer is laminated is known. Among them, the laminated type photoreceptor can obtain a highly sensitive photoreceptor by combining a charge generation material having high charge generation efficiency and a charge transport material having a high mobility and an ionization potential matched to the charge generation material. It is widely used because it offers a wide selection range and a highly safe photoconductor, and because it can easily form a photosensitive layer by coating, has high productivity, and is advantageous in terms of cost.

  In the liquid developing system, such an organic photoreceptor is in contact with a developing solvent used as a carrier for a certain period of time during the developing process. In particular, in a normal color process, a developer having four or more colors is used, and therefore, the developer is exposed to a developing solvent for a longer time. When the photosensitive member is repeatedly exposed to the developing solvent in this way, defects called cracks are generated on the surface of the photosensitive member, which appear as streak defects in the printed image, which may hinder improvement in durability.

  There are various theories about the mechanism of the occurrence of such cracks. For one thing, low molecular components of the photoreceptor are eluted by the developing solvent, creating voids, which are repeatedly subjected to mechanical loads from the surroundings. Fatigue-breaking mechanisms such as growth and cracking can be considered. In such a case, by improving the mechanical properties of the binder resin used in the surface layer of the photoreceptor, it is expected that the voids are prevented from growing and cracking, resulting in improved durability. The

  Examples of the binder resin used for the surface layer of such a photosensitive layer include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate resins, polyester resins, polysulfone resins, phenoxy resins, and epoxy. Thermoplastic resins such as resins and silicone resins and various thermosetting resins are used. Among the various binder resins, the polycarbonate resin has a comprehensively excellent performance, and various structures have been developed and put into practical use.

Moreover, regarding recent liquid development systems, it has been reported that there are cases where a binder resin of a polyester resin is suitably used (see, for example, Patent Documents 1 to 5). This is because the polyester resin is recognized to be superior from the polycarbonate resin in terms of mechanical properties.
Although there is a means for suppressing cracks by forming a curable protective layer (overcoat layer) on the outermost surface of the photoreceptor, this is disadvantageous in terms of cost. Moreover, in order to prevent the protective layer from eroding the lower layer at the time of application, it is necessary to carry out spray application or ring application, and there are significant restrictions on the production surface. Furthermore, there are side effects in terms of electrical characteristics due to the presence of the protective layer. For these reasons, the formation of the protective layer is hardly a general solution.

  On the other hand, most of the conductive support of the photosensitive member (hereinafter referred to as “support” as appropriate) is in the form of a drum (cylinder), but the properties are flexible and the degree of freedom in design when arranging in the apparatus. A sheet or belt-shaped photoconductor is also used for reasons such as a large size. In particular, when a large amount of printing is required at a high speed as in commercial printing, it is preferable from the viewpoint of design and cost to use a sheet or belt-like photoreceptor rather than a large-diameter drum-like photoreceptor. Increasing cases.

  The photosensitive layer is usually formed by applying a coating solution containing a photoconductive substance and a binder resin on a sheet-like support by reverse coating, gravure coating, bar coating, roll coating, blade coating, or the like. Is done. Alternatively, a sheet-like or seamless belt-like support can be wound around a drum-like support and applied by a coating method such as dip coating. In these layer forming methods, a coating solution obtained by dissolving a substance contained in a layer in a solvent is used. In many processes, a coating solution is prepared in advance and stored until it is applied. Therefore, the binder resin is also required to have excellent solubility in the solvent used in the coating process and to be stable in the coating solution after dissolution.

  In Patent Document 6, it is reported that a polyarylate resin having a specific structure is used as a binder resin for a photosensitive layer in order to satisfy the above requirements.

JP 2003-295485 A JP 2006-113352 A JP 2006-113354 A JP 2006-89702 A JP 2005-115091 A JP 2010-96811 A

Conventional photoreceptors do not have sufficient crack resistance for use in liquid development systems, and there have been cases in which cracks are generated on the surface during repeated use, resulting in image defects. In addition, in the case where a polyester resin is used as the binder resin for the surface layer of the photoreceptor as described in Patent Documents 1 to 5, although some improvement was observed, the durability was not sufficient, and the electrical characteristics were also low. In the case of using a polyarylate resin having a specific structure as the binder resin of the photosensitive layer of the photoreceptor as described in Patent Document 6, although durability (abrasion resistance) has been improved, Since it was inferior in terms of electrical characteristics and ozone resistance, it cannot be said that it had sufficient practical performance. In addition, the polyarylate resin often has poor compatibility depending on the structure of the charge transport material, and the residual potential is difficult to decrease, and the selection range of the charge transport material is narrowed.

  The present invention has been made to solve such problems. That is, an object of the present invention is to provide an electrophotographic photosensitive member having sufficient crack resistance even in a liquid developing system and having good electric characteristics and ozone resistance, and an image forming apparatus provided with the same. There is.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have included a compound having a specific structure in the photosensitive layer, whereby the resulting photoreceptor has good electrical characteristics and ozone resistance, and is suitable for development. The inventors have found that they have excellent crack resistance against solvents and have completed the present invention.
That is, the gist of the present invention is to form a sheet-like conductive support having a photosensitive layer containing a compound represented by the following formula (1) without forming a curable protective layer on the outermost surface of the photosensitive member. And an electrophotographic photoreceptor for liquid development, wherein the electrophotographic photoreceptor is used by being wound around.

In the formula (1), Ar ¹ and Ar ² are each independently a condensed polycyclic aromatic hydrocarbon group having 14 or less carbon atoms which may have a substituent, the following formula (2), or the following formula Represents a group represented by (3), Ar ³ and Ar ⁴ each independently represents an aryl group which may have at least one of an alkyl group or an alkoxy group as a substituent, and Ar ⁵ Each independently represents an arylene group which may have a substituent. m represents an integer of 2 to 6.

In the formulas (2) and (3), Ar ⁶ represents an arylene group which may have a substituent, Ar
⁷ and Ar ⁸ represent an aryl group which may have a substituent, and n represents an integer of 2 or 3.
The photoreceptor of the present invention preferably includes a sheet-like conductive support.
Another gist of the present invention resides in an image forming apparatus comprising the electrophotographic photosensitive member for liquid development according to the present invention.

  According to the present invention, it is possible to realize an electrophotographic photosensitive member having sufficient crack resistance in a liquid developing system and having good electrical characteristics and ozone resistance, and an image forming apparatus including the same.

1 is a diagram schematically illustrating a main configuration of an image forming apparatus as an embodiment of the present invention. (A), (b) is a figure which shows typically an example of the unit structure of the liquid developing device of the image forming apparatus as one Embodiment of this invention. 1 is an X-ray diffraction pattern of oxytitanium phthalocyanine used in Examples. 1 is an X-ray diffraction pattern of oxytitanium phthalocyanine used in Examples.

Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the following embodiments and exemplifications, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
[1. Overview]
The electrophotographic photoreceptor of the present invention (the photoreceptor of the present invention) is a photoreceptor for liquid development, and a compound represented by the following formula (1) is hereinafter referred to as “compound according to the present invention” as appropriate. ) Containing a photosensitive layer. In the photosensitive layer, the compound according to the present invention is usually used as a charge transport material. In addition, the photoreceptor is usually provided with a conductive support (support), and the photosensitive layer is provided on the support. In the photoreceptor of the present invention, a sheet-like support is used as the support. It is preferable to provide.

In the formula (1), Ar ¹ and Ar ² are each independently a condensed polycyclic aromatic hydrocarbon group which may have a substituent, the following formula (2), or the following formula (3). Ar ³ and Ar ⁴ each independently represents an aryl group which may have a substituent, and Ar ⁵ each independently has a substituent. Represents an arylene group which may be substituted. m represents an integer of 2 to 6.

In the formulas (2) and (3), Ar ⁶ represents an arylene group which may have a substituent, Ar
⁷ and Ar ⁸ represent an aryl group which may have a substituent, and n represents an integer of 2 or 3.
As a specific configuration of the photoreceptor, for example, a photosensitive layer in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material and a binder resin are laminated on a support ( A layered type photosensitive layer (or a functionally separated type photosensitive layer); a charge generating material dispersed in a layer containing a charge transporting material and a binder resin on a support; Examples thereof include a dispersion type (or single layer type) photoreceptor having a photosensitive layer (single layer type photosensitive layer or dispersion type photosensitive layer). The compound according to the present invention is also used in a single layer type photoreceptor, but is preferably used in a charge transport layer of a multilayer photoreceptor.

[2. Compound according to the present invention]
The photosensitive layer of the photoreceptor of the present invention contains a compound represented by the following general formula (1).

In the formula (1), Ar ¹ and Ar ² are each independently a condensed polycyclic aromatic hydrocarbon group which may have a substituent, the following formula (2), or the following formula (3). Ar ³ and Ar ⁴ each independently represents an aryl group which may have a substituent, and Ar ⁵ may each independently have a substituent. Represents an arylene group. m represents an integer of 2 to 6.

In the formulas (2) and (3), Ar ⁶ represents an arylene group which may have a substituent, Ar
⁷ and Ar ⁸ represent an aryl group which may have a substituent, and n represents an integer of 2 or 3.

Ar ¹ and Ar ² each independently represent a condensed polycyclic aromatic hydrocarbon group which may have a substituent, a group represented by the above formula (2), or the above formula (3).
Examples of the condensed polycyclic aromatic hydrocarbon group include condensed polycyclic aromatic hydrocarbon groups having 14 or less carbon atoms such as 1-naphthyl group, 2-naphthyl group, phenanthryl group, anthryl group, fluorenyl group, and the like. From the viewpoint of compatibility and electrical properties, a condensed polycyclic aromatic hydrocarbon group having 13 or less carbon atoms is preferable, and when the conjugated system is highly expanded, the interaction between molecules becomes strong and the solubility in a solvent decreases. Therefore, a condensed polycyclic aromatic hydrocarbon group having 11 or less carbon atoms is more preferable.

Examples of the substituent that the condensed polycyclic aromatic hydrocarbon group may have include a hydrogen atom, a halogen group, an alkyl group, an aryl group, and an alkoxy group, and among these, a hydrogen atom due to the versatility of the production raw material. An alkyl group and an alkoxy group are preferable, a hydrogen atom and an alkyl group are more preferable from the viewpoint of electrical characteristics as an electrophotographic photoreceptor, and a hydrogen atom is further preferable from the viewpoint of repeated durability characteristics and ozone resistance. Specific examples of the alkyl group and the alkyl group portion in the alkoxy group include, for example, a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, an isopropyl group, and an ethylhexyl group. And cyclic alkyl groups such as an alkyl group and a cyclohexyl group. Among these alkyl groups and the alkyl group part in the alkoxy group, from the viewpoint of handling at the time of production, more preferably an alkyl group having 6 or less carbon atoms, and further preferably from the viewpoint of electrical characteristics of the photoreceptor. It is an alkyl group having 4 or less carbon atoms, and more preferably 2 or less carbon atoms from the viewpoint of charge mobility.

Ar ³ , Ar ⁴ , Ar ⁷ and Ar ⁸ each independently represents an aryl group which may have a substituent. Examples of the aryl group include aromatic hydrocarbon groups having 15 or less carbon atoms such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a phenanthryl group, an anthryl group, and a fluorenyl group. An aromatic hydrocarbon group of 10 or less is preferred, and a phenyl group is more preferred from the viewpoint of solubility in a solvent.

In Ar ³ , Ar ⁴ , Ar ^7, and Ar ⁸ , examples of the substituent that the aryl group may have include a hydrogen atom, a halogen group, an alkyl group, an aryl group, and an alkoxy group. From the versatility of the raw material, a hydrogen atom, an alkyl group, and an alkoxy group are preferable. Specific examples of the alkyl group and the alkyl group portion in the alkoxy group include, for example, a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, an isopropyl group, and an ethylhexyl group. And cyclic alkyl groups such as an alkyl group and a cyclohexyl group. Among these alkyl groups and alkyl group parts in alkoxy groups, methyl group, ethyl group, and ethyl group are considered to have durability against repeated use when used as an electrophotographic photosensitive member, durability against ozone, and low residual potential. Group, a lower alkyl group having 5 or less carbon atoms such as 2-propyl group, and an alkoxy group having 5 or less carbon atoms such as methoxy group and ethoxy group.

Ar ⁵ and Ar ⁶ each independently represent an arylene group which may have a substituent. Examples of the arylene group include divalent aromatic hydrocarbon groups having 10 or less carbon atoms such as a phenylene group and a naphthylene group. A phenylene group is particularly preferable from the viewpoint of versatility of the production raw material.
In Ar ⁵ and Ar ⁶ , the arylene group may have a substituent as a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkylamino group having 2 to 4 carbon atoms. Group, an aryl group having 6 to 10 carbon atoms and the like, specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, methoxy, ethoxy, propoxy, butoxy, N, N-dimethylamino, N, N-diethylamino, phenyl, 4-tolyl, 4-ethylphenyl, 4-propylphenyl, 4-butylphenyl, naphthyl and the like can be mentioned. Among these, a hydrogen atom and an alkyl group having 1 to 4 carbon atoms are particularly preferable from the viewpoint of electrical characteristics.

  In the above formula (1), m is an integer of usually 2 or more in terms of improving the electrical characteristics of the electrophotographic photosensitive member, and there is no particular upper limit unless it adversely affects the electrical characteristics, but an integer of 5 or less Is preferable, and an integer of 3 or less is more preferable. From the viewpoint of compatibility with the photosensitive layer and production cost, m is preferably 2 or 3, particularly preferably m = 2.

In the above formula (2), n represents an integer of 2 or 3, and 2 is preferable from the viewpoint of production cost.
It said Ar ¹ and Ar ² are, from the standpoint of ease of manufacture, it is preferable that Ar ¹ and Ar ² are the same, from the viewpoint of crack resistance, Ar ¹ and Ar ² are both condensed polycyclic aromatic hydrocarbon More preferably, it is a group.
Examples of the compound represented by the formula (1) include the following exemplary compounds, but are not limited to these compounds.

[3. Conductive support]
Examples of the material of the support include, for example, a metal material such as aluminum, aluminum alloy, stainless steel, copper, and nickel; a resin material that includes a conductive powder such as metal, carbon, and tin oxide; In general, a resin, glass, paper, or the like on which a conductive material such as nickel or ITO (indium tin oxide alloy) is deposited or applied is used. In addition, a conductive material having an appropriate resistance value may be applied to the surface of the support such as a metal material for the purpose of controlling conductivity and surface properties and for covering defects.

  As the form of the support, for example, a drum shape, a sheet shape, a belt shape or the like is used. Among these, in the photoreceptor of the present invention, it is preferable to use a sheet-like support. Among these, specifically, those in which a metal layer is formed on a film such as a biaxially stretched film are particularly preferably used. This is because the degree of freedom in design in the image forming apparatus, the ease of application of the coating solution for forming the photosensitive layer, the low cost and the like.

  Examples of the material of the film include linear polyester resins such as polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene terephthalate resin; polyolefin resins such as polyethylene resin and polypropylene resin; and polyvinyl chloride resin. Among these, a linear polyester resin is preferable from the viewpoint of mechanical strength and dimensional stability, and a polyethylene terephthalate resin is particularly preferable. From the viewpoint of heat resistance, polyethylene terephthalate resin and polyethylene naphthalate resin are preferable. In addition, these resin may use one type and may use two or more types together by arbitrary combinations and arbitrary ratios.

  The thickness of the film is usually 30 μm or more, preferably 50 μm or more, more preferably 70 μm or more, and usually 200 μm or less, preferably 150 μm or less, more preferably 120 μm or less. By setting the thickness within this range, it is advantageous in terms of cost, can prevent deformation (curl) after drying, and can ensure sufficient mechanical strength such as tensile strength.

  Moreover, as a metal of the metal layer which comprises a support body, although copper, nickel, zinc, aluminum, ITO (indium-tin oxide) etc. are mentioned, for example, aluminum is preferable. In addition, these metals may use 1 type and may use 2 or more types together by arbitrary combinations and arbitrary ratios. The thickness of the metal layer is usually 40 nm or more and 100 nm or less.

When a metal layer is formed on the film, the metal vapor deposition layer is usually formed by a vapor deposition method. As the vapor deposition method, for example, a known vapor deposition method such as an electrothermal melting deposition method, an ion beam vapor deposition method, or an ion plating method of the metal is used.
Moreover, as a metal layer, metal foil, such as aluminum foil and nickel foil, and the laminate film which laminated | stacked these metals can be used. In this case, the thickness of the metal foil is preferably 5 μm or less. Further, a conductive material having a more appropriate resistance value can be laminated on the metal foil.

The surface of the support may be smooth, or may be roughened, for example, by mixing particles having a large particle diameter with a resin. By roughening the surface, it is possible to obtain effects such as suppressing the occurrence of interference fringes with respect to coherent light such as a laser and increasing the adhesion of the photosensitive layer.
[4. Undercoat layer]
An undercoat layer may be provided between the support and the photosensitive layer in order to improve adhesion and blocking properties.

As the undercoat layer, a resin, a resin in which particles such as a metal oxide are dispersed, or the like is used. Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one kind of metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide,
Examples thereof include metal oxide particles containing a plurality of metal elements such as calcium titanate, strontium titanate, and barium titanate. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide; or an organic substance such as stearic acid, polyol, or silicone. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. One particle may contain a plurality of crystal states.

One kind of these metal oxide particles may be used, or two kinds may be used in any combination and in any ratio.
Moreover, as the particle size of the metal oxide particles, various particles can be used. Among them, from the viewpoint of characteristics and the stability of the coating liquid for forming the undercoat layer, the average primary particle size is preferably 10 nm or more and 100 nm or less, Especially preferably, they are 10 nm or more and 50 nm or less.

  The undercoat layer is preferably formed with a structure in which metal oxide particles are dispersed in a binder resin. As the binder resin used for the undercoat layer, for example, phenoxy resin, epoxy resin, polyvinyl pyrrolidone resin, polyvinyl alcohol resin, casein, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, etc. are used alone or cured. Can be used in a cured form with the agent. Among these, alcohol-soluble copolymerized polyamide, modified polyamide, and the like are preferable because they exhibit good dispersibility and coatability. In addition, these may use one type and may use two types together by arbitrary combinations and arbitrary ratios.

  The amount ratio of the metal oxide particles to the binder resin can be arbitrarily selected, but is usually 10% by mass or more, preferably 50% by mass or more, more preferably 70% by mass or more, more preferably 100% by mass or more, and usually 500% by mass. % Or less, preferably 400% by mass or less, more preferably 380% by mass or less, and particularly preferably 350% by mass or less. This is for improving the stability and coating property of the coating solution for forming the undercoat layer.

The thickness of the undercoat layer can be arbitrarily selected, but is usually 0.1 μm or more, preferably 0.3 μm or more, more preferably 0.5 μm or more, and usually 25 μm or less, preferably 20 μm or less, more preferably Is 15 μm or less, particularly preferably 10 μm or less. This is to improve the characteristics of the photoreceptor and the coating property of the coating solution for forming the undercoat layer.
The undercoat layer may contain an additive such as a known antioxidant.

Furthermore, it is good also as a two-layer structure of a conductive layer and a blocking layer as an undercoat layer.
[5. Photosensitive layer]
In the photoreceptor of the present invention, the type of the photosensitive layer is not particularly limited, and may be a multilayer photosensitive layer or a single-layer photosensitive layer as long as it contains the compound according to the present invention in the layer. Also good. Of these, a laminate type photosensitive layer is preferable, and among them, it is more preferable that the charge transporting layer contains the compound according to the present invention.

[5-1. Charge generation layer]
The charge generation layer of the multilayer photoconductor contains a charge generation material and usually contains a binder resin and other components used as necessary. Specifically, such a charge generation layer is prepared by, for example, preparing a coating solution (coating solution for forming a charge generation layer) by dissolving or dispersing a charge generation material and a binder resin in a solvent, and forming the coating solution in a sequential lamination type. In the case of a photosensitive layer, it can be obtained by coating and drying on a support (when an undercoat layer is provided, on the undercoat layer), and in the case of a reverse lamination type photosensitive layer, it can be applied and dried on a charge transport layer. .

  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 a charge generation material, specific examples thereof include metal-free phthalocyanine; metals such as copper, indium, gallium, tin, titanium, zinc, vanadium, silicone, germanium, or oxides and halides thereof. And the like coordinated phthalocyanines; Examples of the ligand to the trivalent or higher metal atom 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. .
The thickness of the charge generation layer 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.

The charge generation layer may contain components other than those described above as long as the effects of the present invention are not significantly impaired. For example, the charge generation layer may contain an additive. These additives are used to improve film forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, and the like. For example, plasticizers, antioxidants , Ultraviolet absorbers, electron withdrawing compounds, dyes, pigments, leveling agents, residual potential inhibitors, dispersion aids, visible light shading agents, sensitizers, surfactants and the like. The use of a plasticizer can improve the mechanical strength of the layer, the use of a residual potential inhibitor can suppress the residual potential, the use of a dispersion aid can improve dispersion stability, and a leveling agent can be used. If it is, the applicability | paintability of a coating liquid can be improved. Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of dyes and pigments include various pigment compounds and azo compounds. Examples of surfactants include silicone oil and fluorine-based oil. In addition, an additive may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and arbitrary ratios.
Further, for the purpose of reducing frictional resistance and wear on the surface of the photosensitive member, the surface layer may contain silicone oil and wax, and resin particles such as fluorine resin, polystyrene resin, and silicone resin. Moreover, you may contain the particle | grains of an inorganic compound.

[5-2. Charge transport layer]
The charge transport layer of the multilayer photoreceptor contains a charge transport material and usually contains a binder resin and other components used as necessary. Specifically, such a charge transport layer is prepared by, for example, preparing a coating liquid (coating liquid for forming a charge transport layer) by dissolving or dispersing a charge transport material and a binder resin in a solvent. In the case of a photosensitive layer, it can be obtained by coating and drying on a charge generation layer, and in the case of a reverse lamination type photosensitive layer, on a support (or on an undercoat layer if an undercoat layer is provided). .

  As the charge transport material, the above-mentioned [2. The compounds detailed in [Compound according to the present invention] are used. As the charge transport material, only one type of the compound according to the present invention may be used, or one or more types of charge transport materials other than the compound according to the present invention may be used in combination at any ratio. The charge transport material other than the compound according to the present invention to be used in combination is not particularly limited, and any known material can be used. Examples of known charge transport materials include electron-withdrawing materials such as aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, and quinone compounds such as diphenoquinone; Derivatives, indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, heterocyclic compounds such as benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives and a plurality of these compounds An electron donating substance such as a polymer in which a species is bonded, or a polymer having a group composed of these compounds in the main chain or side chain. Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and those in which a plurality of these compounds are bonded are preferable.

  In order to exert the effect of the compound represented by the formula (1) according to the present invention, the ratio of the compound represented by the formula (1) according to the present invention to the total charge transporting substance is usually 50% by mass or more. From the viewpoint of light attenuation characteristics of the electrophotographic photosensitive member, it is preferably 70% by mass or more, and from the viewpoint of maintaining crack performance, it is most preferably 100% by mass.

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

The ratio between the binder resin and the charge transport material is 10 parts by mass or more of the charge transport material with respect to 100 parts by mass of the binder resin. Among these, 20 parts by mass or more is preferable from the viewpoint of reducing the residual potential, and more preferably 25 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 100 parts by mass or less. Furthermore, it is preferably 80 parts by mass or less from the viewpoint of printing durability, more preferably 70 parts by mass or less from the viewpoint of scratch resistance, and most preferably 60 parts by mass or less from the viewpoint of maintaining crack performance.
The thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, on the other hand, usually 50 μm or less, preferably 45 μm or less, from the viewpoint of long life, image stability, and high resolution. Is in the range of 30 μm or less.

[5-3. Dispersed (single layer) photosensitive layer]
The single-layer type photosensitive layer is formed using a binder resin in order to ensure film strength, in the same manner as the charge transport layer of the multilayer photoconductor, in addition to the charge generation material and the charge transport material. Specifically, a charge generation material, a charge transport material, and various binder resins are dissolved or dispersed in a solvent to prepare a coating solution, and on a conductive support (or an undercoat layer when an undercoat layer is provided). It can be obtained by coating and drying.

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

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

[5-4. 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.

[5-5. Application method of each layer]
There is no restriction | limiting in the formation method of a photosensitive layer, Arbitrary methods can be used. For example, a coating solution obtained by dissolving or dispersing a substance to be contained in each layer in a solvent (charge generating layer forming coating solution, charge transport layer forming coating solution, dispersion type photosensitive layer forming coating solution, etc.) sequentially. It is formed by applying and drying.

The coating method is not particularly limited, and for example, a dip coating method, a spray coating method, a nozzle coating method, a bar coating method, a roll coating method, a blade coating method, or the like can be used. In particular, as a coating method in the case of a photoreceptor (sheet-shaped photoreceptor) provided with a sheet-like support, a coating solution is applied onto the support by a known die coating method, reverse coating method, gravure coating method, bar coating method, or the like. It is formed by coating.

The coated photoreceptor is usually subjected to a drying process until the solvent of the coating film is substantially removed by evaporation. As a drying method, a conventionally known method can be applied. For example, it is performed by at least one of a heating roller, a hot air dryer, a steam dryer, an infrared dryer, a far infrared dryer and the like. The drying temperature is usually in the range of 60 ° C to 140 ° C.
When the photoreceptor of the present invention is a sheet-like photoreceptor, for example, both end portions thereof are joined by a known method such as ultrasonic fusion, and used as an endless belt. Further, for example, the sheet-like photoconductor can be used by being wound around a drum as it is. In the case of winding around a drum, for example, a thin roll may be held inside the drum for unwinding, or a single sheet may be wound.

[6. Image forming apparatus]
Next, an embodiment of an image forming apparatus using the photoconductor of the present invention will be described with reference to the drawings for the main configuration of the apparatus. However, the embodiment of the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
FIG. 1 is a diagram schematically showing a main configuration of an image forming apparatus as an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus according to the present embodiment includes a photoreceptor 1, a charging device 2 as a charging unit, an exposure device 3 as an exposure unit, and a developing device 4 as a developing unit. Further, a transfer device 5 as a transfer unit, a cleaning device 6 as a cleaning unit, and a fixing device (not shown) as a fixing unit are provided as necessary.

The shape of the photoreceptor 1 is not particularly limited as long as it is the photoreceptor of the present invention described above. In FIG. 1, as an example, the above-described photosensitive layer is formed on the surface of a sheet-like support, and ultrasonic welding is performed. An endless belt-shaped photoconductor is shown.
The charging device 2 charges the photoreceptor 1 and is a device that uniformly charges the surface of the photoreceptor 1 to a predetermined potential. In FIG. 1, a corona discharge type charging device (corotron) is shown as an example of the charging device 2. However, for example, a corona charging device such as a scorotron or a contact type charging device such as a charging roller or a charging brush is often used. Used.

  In many cases, the photoreceptor 1 and the charging device 2 are designed to be removable from the main body of the image forming apparatus as a cartridge including both of them (hereinafter referred to as “photosensitive cartridge” as appropriate). For example, when the photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be detached from the image forming apparatus main body, and another new photoreceptor cartridge can be mounted on the image forming apparatus main body. . In addition, the developer described later is often stored in a cartridge and designed to be removable from the main body of the image forming apparatus. It can be removed from the main body of the forming apparatus and another new cartridge can be mounted. Further, a cartridge provided with all of the photosensitive member 1, the charging device 2, and the developer may be used.

  The type of the exposure device 3 is not particularly limited as long as it can expose the photosensitive member 1 to form an electrostatic latent image on the photosensitive surface of the photosensitive member 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, the support of the photoconductor may be made light transmissive, and exposure may be performed by a photoconductor internal exposure method.

The light used for the exposure is arbitrary. For example, the exposure may be performed using monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light with a short wavelength of 380 nm to 500 nm. . In particular, when light having a wavelength of 380 nm to 500 nm is used, the photoconductor can be exposed with light having a smaller spot size, and a high quality image having high resolution and high gradation can be formed. This is preferable when an image is desired.

  The developing device 4 represents a liquid developing device. The developer to be used is usually a toner obtained by dispersing a charged pigment and resin in a developing solvent (usually an organic solvent) having a high insulating property. Since the toner charged in the liquid is electrophoresed in response to the development electric field, the mobility of the toner in the developing solvent with viscosity is related, but the basic electric field model is the same as dry development. It is.

2A and 2B schematically show an example of the unit configuration of the liquid developing device 4. FIG.
The liquid developing device 4 shown in FIG. 2A includes a developing roller 7 and a squeeze roller 8 that are close to or in contact with the photoconductor 1 in this order along the transfer direction of the photoconductor 1. First, a developing solution having a low density is transferred from the developing roller 7 to the photosensitive member, and development is performed. Subsequently, excess developing solvent on the photosensitive member 1 is squeezed out with the squeeze roller 8 while borrowing the power of the electric field. A thin, uniform and high density toner image can be formed on the body 1.

  On the other hand, the liquid developing device 4 shown in FIG. 2B includes a developing roller 7 that is close to the photoreceptor 1 and a squeeze roller 8 that is in contact with the developing roller 7. Then, a thin toner layer having a high density and high charge is formed in advance on the developing roller 7 by an electric field and pressure between the developing roller 7 and the squeeze roller 8 before development, and then this toner layer is developed with the photoreceptor 1. By developing with an electric field between the rollers 7, a high-density toner image can be formed.

If necessary, the liquid developing device 4 may be provided with a cleaning roller 9 for removing the developer remaining on the developing roller 7 and the squeeze roller 8.
The type of the transfer device 5 is not particularly limited. For example, an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method may be used. it can. Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner, and transfers the toner image formed on the photoreceptor 1 onto a recording paper (paper, medium, transfer material) P. Is. FIG. 1 shows a direct transfer method from the photosensitive member to the recording paper P. However, the toner image is transferred from the photosensitive member to an intermediate transfer member such as an intermediate transfer belt and an intermediate transfer roller, and then transferred to the recording paper P. An intermediate transfer method can also be used.

There is no restriction | limiting in particular about the cleaning apparatus 6, For example, arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner.
When the toner transferred onto the recording paper P normally passes through a fixing device (not shown), the toner is heated and heated to a molten state, and is cooled after passing through to fix the toner on the recording paper P.

The type of the fixing device is not particularly limited. For example, a fixing device of an arbitrary method such as heat roller fixing, flash fixing, oven fixing, pressure fixing, or the like can be provided.
In the image forming apparatus configured as described above, an image is recorded as follows by a liquid developing type image forming method using a developer.

That is, as shown in FIG. 1, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2 (charging process). At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.
Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface (exposure process). Then, development of the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1 is performed by the developing device 4 (developing process).

  As shown in FIGS. 2A and 2B, when the charged toner carried on the developing roller 7 of the developing device 4 is in contact with or close to the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photoreceptor. 1 is formed on the photosensitive surface. This toner image is transferred onto the recording paper P by the transfer device 5 (manual printing process). Thereafter, toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6 (cleaning step). After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the toner image through the fixing device and thermally fixing the toner image onto the recording paper P (fixing step).

  Note that the image forming apparatus may have a configuration capable of performing the static elimination process in addition to the above-described configuration. The neutralization step is a step of canceling excess charged charges on the photosensitive member by exposing the photosensitive member or applying an alternating voltage. As the charge removal device, for example, an exposure device such as a fluorescent lamp or LED, a wire capable of applying an alternating current, or the like is used. When exposure is used in the static elimination process, the light intensity is often light having an exposure energy that is three times or more that of exposure light.

Further, the image forming apparatus may be further modified. For example, the image forming apparatus may be configured such that a pre-exposure process, an auxiliary charging process, or the like can be performed, or a full color system using a plurality of types of toners. Good.
Further, for example, instead of the endless belt-like photoconductor, a sheet-like photoconductor may be attached on a metal drum by electrostatic force or the like.

  Note that the photosensitive member 1 can be combined with one or more of a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, a cleaning device 6 and a fixing device, as required. It may be configured as an (electrophotographic cartridge), and the electrophotographic cartridge may be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In this case, similarly to the cartridge described in the above embodiment, for example, when the photosensitive member 1 or other member deteriorates, the electrophotographic cartridge is removed from the image forming apparatus main body, and another new electrophotographic cartridge is replaced with the image forming apparatus. By attaching to the main body, maintenance and management of the image forming apparatus are facilitated.

  The photoreceptor of the present invention as described in detail above has a sufficient crack resistance in a liquid developing system because the photosensitive layer contains a compound having a structure represented by the formula (1) according to the present invention. An electrophotographic photosensitive member having good electrical characteristics and ozone resistance and an image forming apparatus including the same can be realized. Therefore, according to the image forming apparatus described above, high-quality image formation can be performed over a long period of time without causing cracks peculiar to the liquid developing system.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, the following examples are shown in order to explain the present invention in detail, and the present invention is not limited to the following examples unless departing from the gist thereof. Note that “parts” used in the present examples indicate “parts by mass” unless otherwise specified.
Example 1
Aluminum oxide particles having an average primary particle diameter of 13 nm (Aluminum Oxide C, manufactured by Nippon Aerosil Co., Ltd.) were dispersed in a mixed solvent of methanol / 1-propanol with ultrasonic waves to obtain a dispersion slurry of aluminum oxide. The dispersion slurry, a mixed solvent of methanol / 1-propanol (mass ratio 7/3), and ε-caprolactam [
Compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [compound represented by the following formula (B)] / hexamethylenediamine [compound represented by the following formula (C)] / The composition molar ratio of decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [compound represented by the following formula (E)] was 60% / 15% / 5% / 15% / After stirring and mixing the 5% copolymerized polyamide pellets with heating to dissolve the polyamide pellets, an ultrasonic dispersion treatment is performed, whereby the aluminum oxide / copolymerized polyamide is mixed at a mass ratio of 1/1. It was set as the dispersion for undercoat layers of the solid content concentration containing 8.0%.

The coating solution for forming the undercoat layer thus obtained was applied on a polyethylene terephthalate sheet (thickness 75 μm) vapor-deposited on the surface with a wire bar so that the film thickness after drying was 1.2 μm, and dried. Thus, an undercoat layer was provided.
As a charge generation material, 20 parts of titanium oxyphthalocyanine having a powder X-ray diffraction spectrum pattern with respect to CuKα characteristic X-ray shown in FIG. 3 and 280 parts of 1,2-dimethoxyethane are mixed, and pulverized in a sand grind mill for 2 hours to form fine particles Dispersion processing was performed. Subsequently, 400 parts of a 2.5% 1,2-dimethoxyethane solution of polyvinyl butyral (trade name “Denkabutyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 170 parts of 1,2-dimethoxyethane were mixed. Dispersion 1) was thus prepared. Next, the same operation was performed on titanium oxyphthalocyanine having a powder X-ray diffraction spectrum pattern with respect to the CuKα characteristic X-ray shown in FIG. 4 to prepare dispersion 2). A mixture obtained by mixing and stirring these dispersions at a ratio of 1: 1 was applied onto the undercoat layer with a bar coater to form a charge generation layer so that the film thickness after drying was 0.4 μm.

Next, on this film, 35 parts of the charge transport material (1) having the following structure, 100 parts of the binder resin (1) having the following structure (viscosity average molecular weight: 31000), and 8 parts of the antioxidant having the following structure: As a leveling agent, a solution obtained by dissolving 0.1 part of silicone oil in 640 parts of a tetrahydrofuran / toluene (8/2) mixed solvent is applied and dried at 125 ° C. for 20 minutes, resulting in a film thickness of 18 μm after drying. Thus, a charge transport layer was provided to prepare a photoreceptor. This photoreceptor is referred to as a photoreceptor X1.

Example 2
A photoconductor X2 was obtained in the same manner as in Example 1 except that the charge transport material was changed to the charge transport material (2) having the following structure in Example 1.

Example 3
In Example 2, the binder resin of the coating solution for the charge transport layer was changed to binder resin (2) having the following repeating structure (viscosity average molecular weight: 30000), and all the same procedures as in Example 2 were used except that dioxolane was used as a solvent. Photoconductor X3 was obtained.

Example 4
In Example 3, a photoreceptor X4 was obtained in the same manner as in Example 3 except that the charge transport material was changed to 40 parts.
Example 5
A photoconductor X5 was obtained in the same manner as in Example 1 except that 28 parts of the charge transport material (3) was used instead of the charge transport material (1).

Example 6
A photoreceptor X6 was obtained in the same manner as in Example 1 except that 30 parts of the charge transport material (4) having the following structure was used as the charge transport material in Example 1.

Comparative Example 1
In Example 1, a photoreceptor Y1 was obtained in the same manner as in Example 1 except that the charge transport material (5) having the following structure was used as the charge transport material.

Comparative Example 2
In Comparative Example 1 , a photoreceptor Y2 was obtained in the same manner as Comparative Example 1 except that the binder resin (2) having the above repeating structure was used as the binder resin.
Comparative Example 3
In Example 1, a photoreceptor Y3 was obtained in the same manner as in Example 1 except that the charge transport material (6) having the following structure was used as the charge transport material.

Comparative Example 4
In Comparative Example 1, a photoreceptor Y4 was obtained in the same manner as Comparative Example 1 except that the binder resin (3) (viscosity average molecular weight: 38000) having the following repeating structure was used as the binder resin.

Example 7
A photoconductor Z1 was obtained in the same manner as in Comparative Example 4 except that the charge transport material (2) was used as the charge transport material in Comparative Example 4.
The manufactured photoreceptor sheets X1 to X6, Y1 to Y4, and Z1 were subjected to the following electrical property test and crack test. These results are summarized in Table 1.

<Electrical characteristics test>
Using the electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (basic and application of continuation electrophotographic technology, edited by the Japan Imaging Society, Corona, page 404-405), the photoreceptor sheets X1 to Z1 are Attached to an aluminum drum with a diameter of 80 mm to form a cylindrical shape, the aluminum drum and the aluminum support of the photosensitive sheet are electrically connected, and then the drum is rotated at a constant rotational speed of 60 rpm to measure charging, exposure, and potential. Then, an electrical property evaluation test was conducted by a charge elimination cycle. At that time, the surface potential after 100 ms is obtained when the photosensitive member is charged so that the initial surface potential becomes −700 V, and the light of the halogen lamp is exposed to 1.0 μJ / cm 2 with 780 nm monochromatic light using an interference filter. (Hereinafter sometimes referred to as VL). The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%.

<Crack test>
The photoconductor sheet prepared above was cut into 1 cm × 20 cm strips, and the solvent; Isopar L was thinly applied to the surface of the photoconductor and left for about 3 hours. Tensilon Universal Material Testing Machine
Attached to TENSILON RTM100 (manufactured by A & D Co., Ltd.), Isopar L was applied again and pulled with a force of 30 Newton, and the time until a crack appeared on the surface of the photoreceptor was measured. A photoconductor that is weak in cracking properties generates cracks in a short time, but a photoconductor that is resistant to cracks takes a long time to crack generation.

  As described above, it can be seen from the results of Table-1 that the electrical characteristics and the crack resistance are simultaneously improved by incorporating the compound represented by the formula (1) into the photosensitive layer of the electrophotographic photosensitive member for liquid development. Further, from the comparison between Comparative Example 4 and Example 7, even when a polyarylate resin was used as the binder resin, the electrophotographic photosensitive member of Example 7 was maintained well without greatly deteriorating the electrical characteristics. It is understood that excellent crack resistance is also realized.

<Example 8>
Aluminum is deposited to a thickness of 70 nm on the surface of a biaxially stretched polyethylene terephthalate film having a thickness of 500 μm and having a surface roughened (Ra = 0.1 μm) by including silica particles in the film and having a thickness of 75 μm. A film was provided, wound up, and a roll having a length of 2000 m was obtained.
Next, the coating solution for undercoat layer prepared in Example 1 was reverse coated using the roll of aluminum vapor-deposited polyethylene terephthalate film, and the film thickness after drying was 1.2 μm. Then, an undercoat layer was provided.

Next, using the reverse coating method while unwinding the roll of the aluminum vapor-deposited polyethylene terephthalate film on which the undercoat layer was formed, the coating solution for charge generation layer prepared in Example 1 was dried on it. The charge generation layer was provided by coating so that the film thickness was 0.4 μm.
Next, using the die coating method, the coating liquid for the charge transport layer prepared in Example 2 was unwound from the roll of the aluminum vapor-deposited polyethylene terephthalate film on which the undercoat layer and the charge generation layer were formed. It applied so that the film thickness after drying might be set to 18 micrometers, and provided the electric charge transport layer.

The roll sheet coated with the photosensitive layer thus obtained was cut into a size of 353 mm × 584 mm using a continuous cutting machine to obtain a photoreceptor sheet. Further, from both ends of the sheet, the photosensitive layer was peeled off with a width of 25 mm using acetone and ethanol, and the aluminum vapor deposition layer was also removed on one side using a sodium hydroxide solution. Thus, an electrophotographic photoreceptor A was obtained.
The manufactured photoreceptor sheet A was subjected to the following actual machine test.

<Real machine test>
The photoreceptor sheet A was mounted on a commercially available liquid development type light printing machine, TurboStream manufactured by Hewlett-Packard, and image evaluation was performed. In mounting, the photosensitive sheet was wound around an aluminum drum in the machine, and the photosensitive sheet M was held on the drum by superimposing uncoated areas at both ends. By removing the aluminum layer on one side, it was possible to superimpose easily by static electricity.

Using this photoconductor A, 100 halftone images were output continuously, but there was no change in density and a good image was obtained. Furthermore, there were no problems such as cracks in the photosensitive layer even after repeated use, and there was no problem in practical use.
From the above, it can be seen that only when the charge transport material according to the present invention is used, a photoconductor excellent in all of electric characteristics, image characteristics and crack resistance can be obtained.

Claims (2)

A sheet-like conductive support provided with a photosensitive layer containing a compound represented by the following formula (1) is wound around a drum without forming a curable protective layer on the outermost surface of the photosensitive member. An electrophotographic photosensitive member for liquid development.

(In the formula (1), Ar ¹ and Ar ² are each independently a condensed polycyclic aromatic hydrocarbon group having 14 or less carbon atoms which may have a substituent, the following formula (2), or the following: Represents a group represented by the formula (3), Ar ³ and Ar ⁴ each independently represents an aryl group which may have at least one of an alkyl group or an alkoxy group as a substituent, and Ar ^And each independently represents an arylene group which may have a substituent, and m represents an integer of 2 to 6.

(In the formulas (2) and (3), Ar ⁶ represents an arylene group which may have a substituent, Ar
⁷ and Ar ⁸ represent an aryl group which may have a substituent, and n represents an integer of 2 or 3. )   An image forming apparatus comprising the electrophotographic photosensitive member for liquid development according to claim 1.

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