JP2010276932A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which is more improved in photo sensitivity than heretofore. <P>SOLUTION: In the electrophotographic photoreceptor including a conductive substrate and a photosensitive layer, the photosensitive layer contains a bitropone derivative represented by general formula (1). In general formula (1), R<SP>1</SP>and R<SP>2</SP>each denotes a hydrogen atom, a 1-6C alkyl group, a 6-12C aryl group, a 6-12C aralkyl group, a 3-10C cycloalkyl group or a 1-6C alkoxy group. X<SP>1</SP>and X<SP>2</SP>each denotes a hydrogen atom, a 1-6C alkyl group, a 6-12C aryl group, a 6-12C aralkyl group, a 3-10C cycloalkyl group, a 1-6C alkoxy group or an amino group represented by NR<SB>2</SB>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus such as an electrostatic copying machine or a laser beam printer, and more particularly to an electrophotographic photosensitive member excellent in light sensitivity.

  Electrophotographic photoreceptors of image forming apparatuses using the Carlson process include an organic photoreceptor using an organic material for a photosensitive layer and an inorganic photoreceptor using an inorganic material such as selenium for a photosensitive layer. Organic photoconductors are easier to manufacture than inorganic photoconductors and have a wide range of options for photoconductor materials such as charge generators, charge transport agents, and binder resins, and have a high degree of freedom in structural design. Research is ongoing.

  The organic photoreceptor includes a so-called laminated type photoreceptor composed of a stacked structure of a charge generation layer containing a charge generation agent and a charge transport layer containing a charge transfer agent, and a single charge generation agent and charge transfer agent. There are so-called single-layer type photoreceptors dispersed in one photosensitive layer.

  The single layer type organic photoconductor has an advantage in that it has a simple structure and is easy to manufacture, and suppresses the occurrence of film defects and improves the optical characteristics as compared with the multi-layer type organic photoconductor. In addition, a multilayer organic photoreceptor using a hole transport agent having a high carrier mobility as a charge transport agent is negatively charged, whereas a single layer organic photoreceptor has a hole transport agent as a charge transport agent and Since the electron transport agent is used in combination, one photoconductor can be used for both the positively charged type and the negatively charged type.

  In organic photoreceptors (especially single-layer organic photoreceptors), electron transport agents with high charge mobility are required, but benzoquinone derivatives and naphthoquinone derivatives commonly used as electron transport agents have low charge mobility and light. There is a problem that the sensitivity is insufficient.

  Therefore, it has been proposed to use 3,5-dimethyl-3 ', 5'-di-t-butyldiphenoquinone represented by the following chemical formula (6) as an electron transport agent. In the chemical formula (6), “t-Bu” represents a t-butyl group, and of the two benzene rings, the substituent bonded to the carbon of the benzene ring in the benzene ring that is not a t-butyl group ( That is, only the line segment protruding from the vertex of the hexagon representing the benzene ring represents a methyl group.

JP-A-1-206349

  However, 3,5-dimethyl-3 ′, 5′-di-t-butyldiphenoquinone described in Patent Document 1 has poor compatibility with the binder resin, and the photosensitivity test described in the examples described later. As is clear from the above, the photosensitivity was insufficient.

  An object of the present invention is to provide an electrophotographic photoreceptor having improved photosensitivity as compared with the prior art.

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a conductive substrate and a photosensitive layer, and the photosensitive layer contains a vitropone derivative represented by the following general formula (1). Is the body.

(In General Formula (1), R ¹ and R ² are the same or different and have a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms, which may have 6 to 12 carbon atoms. An aryl group, an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, which may have an alkyl group having 1 to 6 carbon atoms. Among the groups, a group other than a hydrogen atom may further have a substituent, and X ¹ and X ² are the same or different and are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a group having 1 to 6 carbon atoms. An aryl group having 6 to 12 carbon atoms which may have an alkyl group, an aralkyl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, represented by an alkoxy group or an NR ₂ of 1 to 6 carbon atoms An amino group (R is an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms; (A certain number of carbon atoms is an aralkyl group having 6 to 12.) Among these groups, a group other than a hydrogen atom may further have a substituent.

  The vitropone derivative represented by the general formula (1) contained in the photosensitive layer is from a diphenoquinone derivative such as 3,5-dimethyl-3 ′, 5′-di-t-butyldiphenoquinone represented by the chemical formula (6). However, since the electron conjugated system is extended to the carbonyl groups at both ends, it has a wide π electron conjugated plane and is excellent in electron accepting property. In addition, since the benzene ring is present at the center of the molecular skeleton, the π-electron conjugated system is maintained in its planarity, but the molecule is twisted at the portion where the benzene ring and the tropone ring are bonded, and the entire molecule is more than the diphenoquinone derivative Three-dimensional symmetry is reduced. Therefore, the vitropone derivative represented by the general formula (1) has high solubility in a solvent, good compatibility with the binder resin, and is uniformly dispersed in the photosensitive layer.

  For this reason, the photosensitive layer containing the vitropone derivative represented by the general formula (1) has a high electron transport property in a low electric field, and the ratio of recombination of electrons and holes in the layer is reduced. Therefore, the photosensitivity of the electrophotographic photosensitive member is improved.

  In the electrophotographic photoreceptor, the photoreceptor layer is preferably a single layer type. The vitropone derivative represented by the general formula (1) dispersed in the photosensitive layer having a single layer structure inhibits the transport of electrons and holes or causes an interaction with the hole transport agent in the photosensitive layer. Therefore, an electrophotographic photoreceptor having further improved photosensitivity is obtained.

  According to the electrophotographic photoreceptor of the present invention, the vitropone derivative represented by the general formula (1) contained in the photosensitive layer has a high electron transport ability and is excellent in compatibility with the binder resin. The residual potential is effectively reduced and high photosensitivity can be exhibited.

  In the electrophotographic photoreceptor of the present invention, by specifying the photoreceptor layer as a single layer type, the construction of the photoreceptor layer is simple and easy to manufacture, and the occurrence of film defects can be suppressed, and the optical characteristics are improved. Can be improved.

(A)-(c) is a schematic sectional drawing provided in order to demonstrate the structure of a single layer type photoreceptor. (A)-(f) is a schematic sectional drawing provided in order to demonstrate the structure of a laminated type photoreceptor.

  Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail.

The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member provided with a conductive substrate and a photosensitive layer, wherein the photosensitive layer contains a vitropone derivative represented by the general formula (1). Is the body.
[Conductive substrate]
As the conductive substrate, various conductive materials are used, such as aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, Examples thereof include a single metal such as brass, a plastic material on which the above metal is vapor-deposited or laminated, glass coated with aluminum iodide, tin oxide, indium oxide, or the like.

The conductive substrate may be in any form such as a sheet shape or a drum shape, and it is sufficient that the substrate itself has conductivity or the surface of the substrate has conductivity. Further, it is desirable that the conductive substrate has sufficient mechanical strength when used.
[Vitropone derivative]
Next, the vitropone derivative represented by the general formula (1) contained in the photosensitive layer will be described. In the general formula (1), R ¹ and R ² are the same or different groups as described above, and have a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 6 carbon atoms. An aryl group having 6 to 12 carbon atoms, an aralkyl group having 6 to 12 carbon atoms that may have an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and 1 to 6 carbon atoms Are appropriately selected from these alkoxy groups.

In the general formula (1), X ¹ and X ² are the same or different groups as described above, and each represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. An aryl group having 6 to 12 carbon atoms, an aralkyl group having 6 to 12 carbon atoms that may have an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and 1 carbon atom Or an amino group represented by NR ₂ (wherein R is an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms, or The aralkyl group having 6 to 12 carbon atoms, which may have an alkyl group having 1 to 6 carbon atoms, is appropriately selected.

In R ¹ , R ² , X ¹ , X ² and R, examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, and t-butyl. , Pentyl, isopentyl, neopentyl, hexyl and the like.

In R ¹ , R ² , X ¹ , X ² and R, examples of the aryl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms include a phenyl group; methyl, ethyl, propyl Phenyl group having an alkyl group having 1 to 6 carbon atoms such as isopropyl, butyl, s-butyl, t-butyl, pentyl and hexyl groups; naphthyl group; alkyl having 1 to 6 carbon atoms such as methyl and ethyl groups Naphthyl group having a substituent; biphenylyl group; o-tolyl group, m-tolyl group, p-tolyl group; o-cumenyl group, m-cumenyl group, p-cumenyl group; 2,3-xylyl group, etc. .

In R ¹ , R ² , X ¹ , X ² and R, examples of the aralkyl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms include benzyl, α-methylbenzyl, phenethyl, Examples include styryl, cinnamyl, 3-phenylpropyl, 4-phenylbutyl, 5-phenylpentyl, 6-phenylhexyl and the like.

In R ¹ , R ² , X ¹ and X ² , examples of the cycloalkyl group having 3 to 10 carbon atoms include groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

In R ¹ , R ² , X ¹ and X ² , as the alkoxy group having 1 to 6 carbon atoms, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, s-butoxy, t-butoxy, pentyloxy , Groups such as isopentyloxy, neopentyloxy, hexyloxy and the like.

Among R ¹ , R ² , X ¹ , X ² and R, the alkyl group having 1 to 6 carbon atoms, the aryl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms, the carbon number The aralkyl group having 6 to 12 carbon atoms, the cycloalkyl group having 3 to 10 carbon atoms, and the alkoxy group having 1 to 6 carbon atoms each independently having a 1 to 6 alkyl group each independently have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen group, a carboxy group, an ester group, an acyl group, an amino group, an alkylamino group, a nitro group, a mercapto group, and an aryl group.
(Synthesis method)
As shown in the following reaction formula (1), in the presence of a Pd (0) catalyst, 1 part of a 5-iodotropone derivative represented by the formula (4A) and 1 part of a 5-iodotropone derivative represented by the formula (4B) 1 part of a boron reagent represented by the formula (5) having a benzene ring sandwiched between tropone rings and extending the π-conjugated system is added, and one part of the general formula is formed by a one-stage Suzuki-Miyaura cross-coupling reaction. A vitropone derivative represented by (1) can be synthesized.

(Concrete example)
Specific examples of the vitropone derivative represented by the general formula (1) include compounds represented by the following chemical formulas (1-1), (1-2), and (1-3). In the chemical formulas (1-1) and (1-2), “Me” represents a methyl group, and in the chemical formula (1-3), “Et” represents an ethyl group.

The vitropone derivative represented by the chemical formula (1-1) is a general formula (1) in which R ¹ and R ² are hydrogen atoms, and X ¹ and X ² are C 1 alkoxy groups, that is, methoxy groups (—OCH ₃ ) shows a vitrotropone derivative. The molecular weight is 346.4.

In the general formula (1), R ¹ and R ² are alkoxy groups having 6 carbon atoms, that is, hexyloxy groups (—OC ₆ H ₁₃ ), and X ¹ and A bitropone derivative in which X ² is an alkoxy group having 1 carbon atom, that is, a methoxy group (—OCH ₃ ) is shown. The molecular weight is 546.7.

The vitropone derivative represented by the chemical formula (1-3) is an amino group (R is a carbon atom) in which R ¹ and R ² are hydrogen atoms and X ¹ and X ² are NR ₂ in the general formula (1). A bitropone derivative which is an alkyl group of formula ( ₂ ), that is, a diethylamino group (-NEt2) is shown. The molecular weight is 428.6.
[Configuration of photosensitive layer]
In the electrophotographic photoreceptor of the present invention, the photosensitive layer containing the vitropone derivative represented by the general formula (1) is provided on a conductive substrate. The photosensitive layer is composed of a charge generating agent and a charge transporting agent mixed in the same layer, a so-called single layer type photoreceptor, a layer containing a charge generating agent (charge generating layer) and a charge transporting agent. Although different from the case of a so-called laminated type photoconductor obtained by separating the contained layer (charge transport layer), each photosensitive layer contains each component such as a charge generator and a charge transport agent together with a binder resin and the like. It is formed by dissolving and dispersing in a solvent, coating the coating solution thus obtained on a conductive substrate (directly or via an undercoat layer), and drying.

  The electrophotographic photosensitive member of the present invention may be either a single layer type or a multilayer type, but the effect of using the vitropone derivative represented by the general formula (1) is noticeable in the single layer type.

  The single-layer type electrophotographic photosensitive member is obtained by providing a single photosensitive layer on a conductive substrate, and this photosensitive layer is at least a charge generator, a vitropon represented by the general formula (1). An electron transporting agent including a derivative and a single layer structure in which a binder resin is dispersed. The photosensitive layer further contains a hole transport agent. This single-layer type photoreceptor can be applied to both positive charging and negative charging, but it is particularly preferable to use a positive charging type. As the single-layer type electrophotographic photoreceptor 10, for example, there is one in which a photosensitive layer 14 is formed on the surface of a conductive substrate 12 as shown in FIG.

  On the other hand, the multilayer electrophotographic photoreceptor is one in which at least a charge generation layer and a charge transport layer are provided on a conductive substrate, and the charge transport layer has a vitropon represented by the general formula (1) as an electron transport agent. It contains a derivative. As the laminated electrophotographic photoreceptor 20, for example, as shown in FIG. 2 (a), a charge generation layer 24 and a charge transport layer 22 are provided in this order on a conductive substrate 12, or FIG. 2 (b). As shown in FIG. 2, there is one in which a charge transport layer 22 and a charge generation layer 24 are provided in this order on a conductive substrate 12. The multi-layer electrophotographic photosensitive member of the present invention has a greatly reduced residual potential and improved sensitivity as compared with the conventional multi-layer electrophotographic photosensitive member. In order to more smoothly transfer electrons from the charge generation layer to the charge transport layer, the charge generation layer preferably contains a vitropone derivative represented by the general formula (1).

  The vitropone derivative represented by the general formula (1) has good solubility in a solvent and compatibility with a binder resin, and excellent matching with a charge generating agent. It is performed smoothly and has excellent electron transport properties in a low electric field.

  For example, in a positively charged single layer type photoreceptor, a charge generating agent that has absorbed light by exposure to the photoreceptor produces ion pairs [holes (+) and electrons (−)]. Electrons released from the charge generating agent are smoothly injected into an electron transporting agent made of a vitropone derivative represented by the general formula (1). Next, transfer of electrons between the electron transfer agents causes the electrons to move to the surface of the photosensitive layer, and the positive charge (+) previously charged on the surface of the photosensitive layer is canceled out. On the other hand, holes (+) are injected into the hole transport agent, move to the surface of the conductive substrate without being trapped in the middle, and cancel the negative charge (−) on the surface of the conductive substrate. Thus, it is considered that the sensitivity of the positively charged single layer type photoreceptor is improved. The negatively charged single-layer type photoreceptor only has the charge transfer direction opposite to that described above, and similarly improves the sensitivity.

  In order for the ion pairs generated from the charge generating agent to be free carriers and effectively cancel the surface charge, it is better that the rate at which the ion pairs recombine and disappear is small.

  In the electrophotographic photosensitive member, various electron transport agents may be contained in the photosensitive layer as an electron transport agent together with the vitropone derivative represented by the general formula (1). From the viewpoint of minimizing the decrease in photosensitivity of the electrophotographic photosensitive member due to the inclusion of an electron transport agent other than the vitropone derivative represented by the general formula (1), other than the vitropone derivative represented by the general formula (1) As the electron transport agent, it is preferable to contain an electron transport agent having high electron transport ability.

Examples of electron transport agents other than the vitropone derivative represented by the general formula (1) include quinone compounds such as benzoquinone compounds, diphenoquinone compounds, naphthoquinone compounds, anthraquinone compounds, malononitrile compounds, thiopyran compounds, Examples include fluorenone compounds such as 2,4,8-trinitrothioxanthone and 3,4,5,7-tetranitro-9-fluorenone, dinitroanthracene, dinitroacridine, and nitroanthraquinone.
[Charge generator]
Examples of the charge generator include X-type metal-free phthalocyanine (x-H ₂ Pc) represented by the following chemical formula (2-1), Y-type oxotitanyl phthalocyanine (Y) represented by the following chemical formula (2-2) -TiOPc), perylene pigments, bisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments and the like.

  In addition to the exemplified charge generating agents, powders of inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, pyrylium salts, ansanthrone pigments, triphenylmethane pigments, selenium Conventionally known charge generating agents such as pigments, toluidine pigments, pyrazoline pigments and quinacridone pigments may be used.

  A charge generating agent is used individually by 1 type or in mixture of 2 or more types so that it may have an absorption wavelength in a desired area | region. In addition, among charge generating agents, image forming apparatuses for digital optical systems such as laser beam printers and facsimiles that use a light source such as a semiconductor laser, in particular, require a photoreceptor having sensitivity in a wavelength region of 700 nm or more. For example, phthalocyanine pigments such as metal-free phthalocyanine and oxo titanyl phthalocyanine are preferably used. The crystal form of the phthalocyanine pigment is not particularly limited, and various types can be used.

On the other hand, an analog optical image forming apparatus such as an electrostatic copying machine using a white light source such as a halogen lamp requires a photosensitive member having sensitivity in the visible region. For example, a perylene pigment, a bisazo pigment, etc. Are preferably used.
[Hole transport agent]
Examples of the hole transport agent include various compounds having high hole transport ability, such as benzidine derivatives and oxadiazoles such as 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole. Compounds, styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, organic polysilane compounds, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazones Compounds, triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, nitrogen-containing cyclic compounds, condensation Used by polycyclic compounds It is. Among these, examples of the benzidine derivative include compounds represented by the following chemical formula (3). In the chemical formula (3), the substituent bonded to the carbon of the benzene ring (that is, only the portion protruding from the vertex of the hexagon representing the benzene ring) represents a methyl group.

These hole transport agents are used alone or in combination of two or more. Further, when a hole transporting agent having film forming properties such as polyvinyl carbazole is used, the binder resin is not necessarily required.
[Binder resin]
As the binder resin for dispersing the above-described components, various resins conventionally used in the photosensitive layer can be used. For example, styrene polymer, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer Polymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, ionomer, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, Thermoplastic resins such as polyether resins and polyester resins, silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, other crosslinkable thermosetting resins, epoxy acrylate resins, urethane - photocurable resins such as acrylate copolymer resin. These binder resins are used alone or in combination of two or more. Among these, preferred resins are styrene polymers, acrylic polymers, styrene-acrylic copolymers, polyesters, alkyd resins, polycarbonates, polyarylates, and the like.
[Method for producing electrophotographic photosensitive member]
Next, a method for producing an electrophotographic photoreceptor will be described.

  A single-layer type electrophotographic photosensitive member dissolves or disperses an electron transport agent including at least a vitropone derivative represented by the general formula (1) in an appropriate solvent together with a charge generator, a hole transport agent, a binder resin, and the like. The coating solution thus prepared is applied on a conductive substrate by means such as coating and dried.

  In a single-layer type photoreceptor, the charge generator is preferably blended in an amount of 0.1 to 50 parts by weight, more preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the binder resin, and electron transport. The agent is preferably blended at a rate of 5 to 100 parts by mass, more preferably 10 to 80 parts by mass. Further, the hole transport agent is preferably blended at a ratio of 5 to 500 parts by mass, more preferably 25 to 200 parts by mass. Furthermore, the total amount of the hole transport agent and the electron transport agent is preferably 20 to 500 parts by mass, more preferably 30 to 200 parts by mass with respect to 100 parts by mass of the binder resin. When the electron-accepting compound is contained in the single-layer type photosensitive layer, the content of the electron-accepting compound is preferably 0.1 to 40 parts by mass with respect to 100 parts by mass of the binder resin. More desirably, it is ˜20 parts by mass.

  The thickness of the single-layer type photosensitive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm.

  In order to obtain a multilayer electrophotographic photosensitive member, first, a charge generation layer containing a charge generation agent is formed on a conductive substrate by means of vapor deposition or coating. Next, a coating solution containing an electron transfer agent containing at least the vitropone derivative represented by the general formula (1) and a binder resin is applied onto the charge generation layer by means such as coating and dried. A charge transport layer is formed.

  In the multilayer photoconductor, the charge generating agent and the binder resin constituting the charge generating layer can be used in various ratios, but the charge generating agent is preferably 5 with respect to 100 parts by mass of the binder resin. It is appropriate to blend in a proportion of ˜1000 parts by mass, more preferably 30 to 500 parts by mass. When an electron-accepting compound is contained in the charge generation layer, the electron-accepting compound is preferably blended in an amount of 0.1 to 40 parts by weight, more preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the binder resin. It is appropriate to do. When the charge generating layer contains an electron transporting agent, the electron transporting agent is preferably blended in an amount of 0.5 to 50 parts by weight, more preferably 1 to 40 parts by weight with respect to 100 parts by weight of the binder resin. Is appropriate.

  The electron transport agent and the binder resin constituting the charge transport layer can be used in various proportions within a range where charge transport is not hindered and a range where crystallization does not occur, but the charge generated in the charge generation layer by light irradiation. Is preferably 10 to 500 parts by mass, and more preferably 25 to 100 parts by mass with respect to 100 parts by mass of the binder resin. When the electron-accepting compound is contained in the charge transport layer, the electron-accepting compound is preferably blended in an amount of 0.1 to 40 parts by weight, more preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the binder resin. It is appropriate to do.

  The thickness of the laminated photosensitive layer is preferably about 0.01 to 5 μm, more preferably about 0.1 to 3 μm for the charge generation layer, and preferably 2 to 100 μm for the charge transport layer. It is about 5-50 micrometers.

  In the single layer type photoreceptor, in addition to the configuration shown in FIG. 1A, the characteristics of the photoreceptor are hindered between the conductive substrate 12 and the photosensitive layer 14 as shown in FIG. 1B. The barrier layer 16 may be formed as long as it is not. Further, as shown in FIG. 1C, a protective layer 18 may be formed on the surface of the photoreceptor layer 14. On the other hand, in the laminated type photoconductor, in addition to the configuration shown in FIG. 2A and the configuration shown in FIG. 2B, as shown in FIG. 2C, the conductive substrate 12 and the charge generation layer 24 are provided. Between the charge generation layer 24 and the charge transport layer 22 as shown in FIG. 2D. The layer 16 may be formed, or as shown in FIG. 2E, the barrier layer 16 may be formed between the conductive substrate 12 and the charge transport layer 22, or FIG. ), A barrier layer 16 may be formed between the charge transport layer 22 and the charge generation 24. Further, a protective layer may be formed on the surface of the multilayer photoreceptor.

  Each of the single-layer and multilayer photosensitive layers has various additives known per se, for example, an antioxidant, a radical scavenger, a singlet quencher, and an ultraviolet absorber as long as the electrophotographic characteristics are not adversely affected. Deterioration preventing agents such as agents, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like can be blended. In order to improve the sensitivity of the photosensitive layer, known sensitizers such as terphenyl, halonaphthoquinones, acenaphthylene and the like may be used in combination with the charge generator.

  The photosensitive layer formed on the conductive substrate is produced by applying and drying a coating solution prepared by dissolving or dispersing the resin composition containing the above-described components in a solvent on the conductive substrate. That is, the charge generator, charge transport agent (hole transport agent, electron transport agent), binder resin and the like exemplified above, together with an appropriate solvent, are known methods such as a roll mill, ball mill, attritor, paint shaker or super A coating solution may be prepared by dispersing and mixing using a sonic disperser or the like, and this may be applied and dried by a conventional method.

  As the solvent for preparing the coating solution, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, and benzene. , Aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, cyclohexanone And the like, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide, dimethylsulfoxide and the like. These solvents are used singly or in combination of two or more.

  Further, a surfactant, a leveling agent or the like may be used in order to improve the dispersibility of the charge transport material or the charge generation material and the smoothness of the photosensitive layer surface.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all by the Example.
[Synthesis of Vitropone Derivatives]
(Synthesis Example 1)
The synthesis of the vitropone derivative represented by the chemical formula (1-1) was performed as follows along the following reaction formula (1-1).

Under an inert gas atmosphere, 0.34 g (1.3 mmol) of the compound represented by formula (4-1), 0.11 g (0.65 mmol) of the compound represented by formula (5-1), and 15 mg of palladium acetate. 100 ml of dry dimethylformamide (dry-DMF) was added to 80 mg (20 mol%) of tri-o-tolylphosphine and 0.89 g (6.5 mmol) of potassium carbonate, and the mixture was stirred at 90 ° C for 5 hours. Then, the reaction product was poured into water and extracted with ether. After the solvent was distilled off, the residue was purified by column chromatography to obtain 0.18 g of a vitropone derivative represented by the chemical formula (1-1). The yield was 80%. In the chemical formula (4-1), “Me” represents a methyl group.
(Synthesis Example 2)
The synthesis of the vitropone derivative represented by the chemical formula (1-2) was performed as follows along the following reaction formula (1-2).

By reacting in the same manner as in Synthesis Example 1 except that 0.24 g of the compound represented by the formula (5-2) in the same molar amount was used instead of the compound represented by the formula (5-1). Thus, 0.23 g of a vitropone derivative represented by the chemical formula (1-2) was obtained. The yield was 65%.
(Synthesis Example 3)
The synthesis of the vitropone derivative represented by the chemical formula (1-3) was performed as follows along the following reaction formula (1-3).

  By reacting in the same manner as in Synthesis Example 1 except that 0.39 g of the compound represented by the formula (4-2) in the same molar amount was used instead of the compound represented by the formula (4-1). Thus, 0.21 g of a vitropone derivative represented by the chemical formula (1-3) was obtained. The yield was 75%. In the chemical formula (4-2), “Et” represents an ethyl group.

  In addition, the molecular weight of the compound represented by Formula (4-1) is 262, the molecular weight of the compound represented by Formula (4-2) is 303.1, and is represented by Formula (5-1). The molecular weight of the compound is 165.7, and the molecular weight of the compound represented by the formula (5-2) is 336.1.

[Manufacture of electrophotographic photosensitive member]
Example 1
An X-type metal-free phthalocyanine (x-H ₂ Pc) represented by the chemical formula (2-1) is used as a charge generating agent, and a benzidine derivative represented by the chemical formula (3) is used as a hole transporting agent. A vitropone derivative represented by the chemical formula (1-1) was used as a transport agent. 5 parts by mass of the charge generating agent, 50 parts by mass of a hole transporting agent, 30 parts by mass of an electron transporting agent, and 100 parts by mass of a binder resin (bisphenol Z type polycarbonate resin having a viscosity average molecular weight of 50,000) are mixed with 800 parts by mass of a solvent (tetrahydrofuran). A coating solution for a single-layer type photosensitive layer was prepared by mixing and dispersing for 50 hours with a part in a ball mill. Next, this coating solution is applied on a conductive substrate (aluminum tube) by dip coating, and dried with hot air at 100 ° C. for 60 minutes to obtain a single-layer electrophotographic photosensitive member having a photosensitive layer with a thickness of 30 μm. Manufactured.
(Example 2)
As a charge generating agent, instead of X-type metal-free phthalocyanine (x-H ₂ Pc) represented by chemical formula (2-1), Y-type oxotitanyl phthalocyanine (Y-TiOPc) represented by chemical formula (2-2) A single-layer type photoreceptor was produced in the same manner as in Example 1 except that was used.
(Example 3)
As the electron transporting agent, a single layer was formed in the same manner as in Example 1 except that the vitropone derivative represented by the chemical formula (1-2) having the same mass was used instead of the vitropone derivative represented by the chemical formula (1-1). Type photoreceptors were produced.
Example 4
Y-type oxotitanyl phthalocyanine (Y-TiOPc) represented by chemical formula (2-2) instead of X-type metal-free phthalocyanine (x-H ₂ Pc) represented by chemical formula (2-1) as a charge generator A single layer type photoreceptor was produced in the same manner as in Example 3 except that was used.
(Example 5)
As the electron transporting agent, a single layer was formed in the same manner as in Example 1 except that the vitropone derivative represented by the chemical formula (1-3) having the same mass was used instead of the vitropone derivative represented by the chemical formula (1-1). Type photoreceptors were produced.
(Example 6)
Y-type oxotitanyl phthalocyanine (Y-TiOPc) represented by chemical formula (2-2) instead of X-type metal-free phthalocyanine (x-H ₂ Pc) represented by chemical formula (2-1) as a charge generator A single layer type photoreceptor was produced in the same manner as in Example 5 except that was used.
(Comparative Example 1)
3,5-dimethyl-3 ′, 5′-di-t-butyldiphenoquinone represented by chemical formula (6) having the same mass instead of the vitropone derivative represented by chemical formula (1-1) as an electron transport agent A single-layer type photoreceptor was produced in the same manner as in Example 1 except that was used.
(Comparative Example 2)
Y-type oxotitanyl phthalocyanine (Y-TiOPc) represented by chemical formula (2-2) instead of X-type metal-free phthalocyanine (x-H ₂ Pc) represented by chemical formula (2-1) as a charge generator A single-layer photoreceptor was produced in the same manner as in Comparative Example 1 except that was used.

[Evaluation of photoreceptor characteristics]
The electrophotographic photoreceptors obtained in the above Examples and Comparative Examples were subjected to the following photosensitivity tests, and their sensitivity characteristics (photosensitivity) were evaluated.
(Light sensitivity test)
Using a drum sensitivity tester manufactured by GENTEC, an applied voltage was applied to the surface of each of the photoconductors in the above examples and comparative examples, and the surface was charged to + 700V. Next, monochromatic light having a wavelength of 780 nm (half-width 20 nm, light intensity 16 μW / cm ² ) extracted from the white light of a halogen lamp as an exposure light source using a band-pass filter is applied to the surface of the photoreceptor (irradiation time). The surface potential was measured as a residual potential Vr (unit: V) when 330 milliseconds elapsed from the start of exposure.

  Table 1 shows the types of charge generating agent, hole transporting agent, and electron transporting agent component used for the photoreceptors obtained in the above Examples and Comparative Examples, together with the measurement results of residual potential Vr in the photosensitivity test. .

As is clear from Table 1, the photoreceptors of Examples 1 to 6 using the vitropone derivative represented by the general formula (1) as the electron transport agent are all compared with the corresponding photoreceptors of Comparative Examples 1 and 2. Therefore, the residual potential Vr is small and the photosensitivity is excellent. In particular, the vitropone derivative represented by the chemical formula (1-2) in which R ¹ and R ² are long-chain alkoxy groups (—OC ₆ H ₁₃ ) is represented by the chemical formula (1-1) and the chemical formula (1-3). Compared to the represented vitropone derivative, it shows excellent photosensitivity despite the small amount of the compounded mole. This is presumed to be due to the high solubility.

  As described above in detail, according to the present invention, an electrophotographic photoreceptor excellent in photosensitivity can be obtained by adding a vitropone derivative represented by the general formula (1) to the photosensitive layer. .

  Therefore, the electrophotographic photosensitive member of the present invention is expected to contribute to cost reduction and high performance in various image forming apparatuses such as copying machines and printers.

DESCRIPTION OF SYMBOLS 10 Single layer type electrophotographic photosensitive member 12 Conductive base | substrate 14 Photosensitive layer 16 Barrier layer 18 Protective layer 20 Laminated type electrophotographic photosensitive member 22 Charge transport layer 24 Charge generation layer

Claims (2)

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer,
An electrophotographic photoreceptor in which the photosensitive layer contains a vitropone derivative represented by the following general formula (1).

(In General Formula (1), R ¹ and R ² are the same or different and have a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms, which may have 6 to 12 carbon atoms. An aryl group, an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, which may have an alkyl group having 1 to 6 carbon atoms. Among the groups, a group other than a hydrogen atom may further have a substituent, and X ¹ and X ² are the same or different and are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a group having 1 to 6 carbon atoms. An aryl group having 6 to 12 carbon atoms which may have an alkyl group, an aralkyl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, represented by an alkoxy group or an NR ₂ of 1 to 6 carbon atoms An amino group (R is an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms; (A certain number of carbon atoms is an aralkyl group having 6 to 12.) Among these groups, a group other than a hydrogen atom may further have a substituent.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is a single layer type.