JP2009300586A - Electrophotographic photoreceptor, and image forming apparatus and image forming apparatus for wet development including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor excellent in electrical properties and capable of suppressing the generation of fog even in a high-temperature and high-humidity environment, and an image forming apparatus and an image forming apparatus for wet development including the same. <P>SOLUTION: In the electrophotographic photoreceptor 11, a photosensitive layer containing a charge generating agent, a charge transport agent containing a hole transport agent, and a binder resin is formed on a conductive substrate. The photosensitive layer contains an enamine compound represented by formula (1) as the hole transport agent. In the formula (1), A is a divalent organic group containing an aromatic ring; Ra<SP>1</SP>and Ra<SP>2</SP>are the same or different and 1-12C alkyl substituted by at least one F atom; Rb<SP>1</SP>, Rb<SP>2</SP>, Rc<SP>1</SP>, Rc<SP>2</SP>, Rd<SP>1</SP>, Rd<SP>2</SP>, Re<SP>1</SP>and Re<SP>2</SP>are the same or different and 1-12C alkyl, 6-30C aryl, 6-30C alkenyl or -OR<SP>1</SP>(R<SP>1</SP>is 1-10C alkyl, 1-10C perfluoroalkyl or 6-30C aryl); and n<SP>1</SP>, n<SP>2</SP>, q<SP>1</SP>and q<SP>2</SP>are an integer of 0-4, and o<SP>1</SP>, o<SP>2</SP>, p<SP>1</SP>and p<SP>2</SP>are an integer of 0-5, provided that each of the symbols shows the number of replication of the corresponding substituent. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, an image forming apparatus including the same, and an image forming apparatus for wet development.

Conventionally, as an electrophotographic photoreceptor used in an image forming apparatus or the like, an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer provided on the conductive substrate is known. In recent years, an electrophotographic photosensitive member in which an intermediate layer is interposed between a conductive substrate and a photosensitive layer has been proposed as a photosensitive member that is insulated to suppress leakage.
As such an electrophotographic photosensitive member, a charge generating agent that generates a charge by light irradiation, a charge transporting agent that transports the generated charge, and a binder for forming a layer by dispersing the charge generating agent and the charge transporting agent Organic photoreceptors containing resins are widely used.

  The charge transport agent used in the organic photoreceptor includes an electron transport agent that transports electrons and a hole transport agent that transports holes. Of these, hydrazone compounds, stilbene compounds, enamine compounds and the like have been used in recent years as hole transport agents, but they did not necessarily satisfy the hole transport ability. Therefore, it has been difficult to obtain an electrophotographic photosensitive member having sufficient electric characteristics.

Then, in order to solve the problem of such hole transport ability, for example, Patent Documents 1 to 3 disclose bisenamine stilbene compounds having a specific structure as hole transport agents having excellent mobility.
Since the bisenamine stilbene compounds described in Patent Documents 1 to 3 can exhibit a sufficient hole transport ability, an electrophotographic photoreceptor excellent in electrical characteristics can be obtained.
Japanese Patent No. 3464070 JP 2005-53897 A JP 2006-98584 A

However, the bis-enamine stilbene compounds described in Patent Documents 1 to 3 are not always sufficiently soluble in a solvent. For this reason, a part of the hole transport agent may be crystallized and deposited during the production of the electrophotographic photosensitive member. In addition, the electrophotographic photosensitive member in which a part of the hole transporting agent is crystallized and deposited easily deteriorates the electrical characteristics such as sensitivity. In an image forming apparatus provided with an electrophotographic photosensitive member having insufficient electrical characteristics, fog is likely to occur, and the quality of an obtained image is likely to be deteriorated. In particular, the electrical characteristics of the electrophotographic photosensitive member are likely to deteriorate and the fog is likely to occur in a high temperature and high humidity environment.
Further, when the hole transporting agent has a structure having excellent solubility in a solvent, the hole transporting ability tends to be lowered although the solubility is improved. Therefore, it is desired that the hole transport agent has excellent solubility and hole transport ability.

Furthermore, the electrophotographic photosensitive member produced using the bis-enamine stilbene compound described in Patent Documents 1 and 2 as a hole transporting agent is mainly considered for use as an electrophotographic photosensitive member for dry development. No mention is made of use as an electrophotographic photosensitive member for development.
By the way, since the electrophotographic photosensitive member for wet development is exposed to a liquid developer for a long time, the components constituting the electrophotographic photosensitive member, particularly the hole transport agent, are likely to elute, and the electric characteristics of the electrophotographic photosensitive member are deteriorated. It was easy. Therefore, when an electrophotographic photosensitive member is used for an image forming apparatus for wet development, it is required to be excellent in durability and solvent resistance and to maintain electric characteristics.
Thus, the hole transport agent is required to have conflicting properties such that it is excellent in solubility in a solvent when an electrophotographic photosensitive member is produced and is difficult to dissolve in a solvent when the electrophotographic photosensitive member is used.

  The present invention has been made in view of the above circumstances, and is an electrophotographic photosensitive member that has excellent electrical characteristics and can suppress the occurrence of fog even in a high-temperature and high-humidity environment, an image forming apparatus including the same, and an image forming apparatus for wet development It aims at realization.

As a result of intensive studies, the present inventors have selected and used an amine having an aryl group having a specific substituent as an amine that forms an enamine skeleton in the production of a hole transport agent. It has been found that a hole transporting agent having improved solubility in a solvent while maintaining its performance is obtained, and crystallization during the production of an electrophotographic photoreceptor is suppressed.
Furthermore, by using the specific amine described above, a hole transporting agent excellent in compatibility with the binder resin can be obtained, and an electrophotographic photosensitive member produced using the hole transporting agent has a hole transporting property. The present inventors have found that the elution amount of the agent can be reduced and have completed the present invention.

  That is, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which a photosensitive layer containing a charge generating agent, a charge transporting agent including a hole transporting agent, and a binder resin is formed on a conductive substrate. The photosensitive layer contains an enamine compound represented by the following general formula (1) as the hole transport agent.

In the formula (1), A is a divalent organic group containing an aromatic ring, and Ra ¹ and Ra ² are the same or different and each is an alkyl group having 1 to 12 carbon atoms substituted with at least one fluorine atom. Rb ¹ , Rb ² , Rc ¹ , Rc ² , Rd ¹ , Rd ² , Re ¹ , Re ² are the same or different and are each an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 30 carbon atoms , An alkenyl group having 6 to 30 carbon atoms, or —OR ¹ (where R ¹ is an alkyl group having 1 to 10 carbon atoms, a perfluoroalkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms). N ¹ , n ² , q ¹ , and q ² representing the number of repeating substituents are integers of 0 to 4, and o ¹ , o ² , p ¹ , and p ² are integers of 0 to 5. .

The Ra ¹ and Ra ² are preferably —CH ₂ (CF ₂ ) _r CF ₃ . However, r is an integer of 0-3.
Furthermore, it is preferable that said A is 1 type chosen from the group which consists of a compound represented by following formula (2-1)-(2-6).

Further, the photosensitive layer has a single layer structure containing the charge generating agent, charge transporting agent, and binder resin in the same layer.
Further, the photosensitive layer has a laminated structure having a charge generation layer containing at least the charge generation agent and a charge transport layer containing the charge transfer agent and the binder resin.

The image forming apparatus of the present invention includes the electrophotographic photosensitive member of the present invention, and a charging unit, an exposing unit, a developing unit, and a transferring unit are disposed around the electrophotographic photosensitive member, and the electrophotographic photosensitive member is provided. It is characterized by not having a charge eliminating means for removing charges on the surface of the body.
The image forming apparatus for wet development of the present invention includes the electrophotographic photosensitive member of the present invention, and a charging unit, an exposing unit, a developing unit, and a transfer unit are disposed around the electrophotographic photosensitive member, and A liquid developer in which toner is dispersed in a hydrocarbon solvent is used.

The electrophotographic photosensitive member of the present invention has excellent electrical characteristics and can suppress the occurrence of fogging even in a high temperature and high humidity environment.
The electrophotographic photosensitive member of the present invention is suitable for an image forming apparatus for wet development using a liquid developer because the hole transport agent hardly dissolves and is excellent in durability and solvent resistance.
Further, since the image forming apparatus of the present invention and the image forming apparatus for wet development include the electrophotographic photosensitive member of the present invention, generation of fog is suppressed and a high quality image can be obtained.

[Electrophotographic photoreceptor]
In the electrophotographic photoreceptor of the present invention, a photosensitive layer containing a charge generating agent, a charge transporting agent, and a binder resin is formed on a conductive substrate.

<Conductive substrate>
Examples of the material of the conductive substrate include metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass, and the like. An oxide film formed by oxidation treatment; a plastic material on which the metal is deposited or laminated; a glass coated with aluminum iodide, tin oxide, indium oxide, etc .; a plastic material in which conductive fine particles such as carbon black are dispersed Etc.
In the present invention, “conductive” means that the resistance value is 1.0 × 10 ⁸ Ω · cm or less.

Examples of the shape of the conductive substrate include a sheet shape and a drum shape. The shape of the conductive substrate may be appropriately determined according to the structure of the image forming apparatus.
The surface of the conductive substrate may be roughened. Thereby, generation | occurrence | production of an interference fringe can be prevented. Examples of the surface roughening treatment include etching, anodizing, wet blasting, sand blasting, rough cutting, and centerless cutting.

<Photosensitive layer>
The photosensitive layer contains a charge generator, a charge transport agent, and a binder resin.

(Charge generator)
A known charge generating agent can be used as the charge generating agent. Specifically, phthalocyanine pigments, perylene pigments, bisazo pigments, diketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, pyrylium Organic photoconductors such as pigments, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments; selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, etc. An inorganic photoconductive agent etc. are mentioned. A charge generating agent may be used individually by 1 type, and may use 2 or more types together.
In addition, as the charge generating agent, compounds (3-1) to (3-4) are preferable.

(Charge transport agent)
The charge transport agent includes a hole transport agent.
In the present invention, the photosensitive layer contains an enamine compound represented by the following general formula (1) as a hole transport agent. Hereinafter, the compound represented by the general formula (1) is referred to as a compound (1). Other compounds are described in the same manner.

A is a divalent organic group containing an aromatic ring, and is preferably one selected from the group consisting of compounds represented by the following formulas (2-1) to (2-6).
When A is a divalent organic group containing an aromatic ring having a specific structure represented by the following formulas (2-1) to (2-6), the compatibility with the binder resin is particularly excellent. At the same time, the injection efficiency from the charge generating agent to the charge transport agent is improved. As a result, excellent durability and electrical characteristics are easily obtained.

Ra ¹ and Ra ² are the same or different and each represents an alkyl group having 1 to 12 carbon atoms substituted with at least one fluorine atom.
As the alkyl group, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group , Undecyl group, dodecyl group and the like.
As such Ra ¹ and Ra ² , —CH ₂ (CF ₂ ) _r CF ₃ is preferable from the viewpoint of the cost of raw materials, the solubility of a compound in a solvent, and the compatibility with a binder resin (however, , R is an integer of 0 to _3. ) Among them, —CH ₂ CF ₃ and —CH ₂ CF ₂ CF ₃ are particularly preferable.

Rb ¹ , Rb ² , Rc ¹ , Rc ² , Rd ¹ , Rd ² , Re ¹ , and Re ² are the same or different and are each an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 30 carbon atoms, and a carbon number 6-30 alkenyl groups, or —OR ¹ . These alkyl group, aryl group, and alkenyl group may or may not have a substituent.
Examples of the alkyl group include the alkyl groups exemplified above.
Examples of the aryl group include phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, anthryl group, phenanthryl group and the like.
Examples of the alkenyl group include a vinyl group, an allyl group, a 1-propenyl group, an isobutenyl group, a 1-butenyl group, and a 2-butenyl group.
In -OR ¹ , R ¹ is an alkyl group having 1 to 10 carbon atoms, a perfluoroalkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms. As an alkyl group and an aryl group, each alkyl group and aryl group which were illustrated previously are mentioned.
Rb ¹ , Rb ² , Rc ¹ , Rc ² , Rd ¹ , Rd ² , Re ¹ , Re ² are preferably methyl groups.

n ¹ , n ² , o ¹ , o ² , p ¹ , p ² , q ¹ , q ² each represent the number of repeating substituents. ^{n 1, n 2, q 1} , q 2 is an integer of ^{0~4, o 1, o 2,} p 1, p 2 is an integer of 0 to 5. From the viewpoint of synthesis, n ¹ , n ² , o ¹ , o ² , p ¹ , p ² , q ¹ , and q ² are preferably 0.

  Examples of compound (1) include compounds (1-1) to (1-5).

Compound (1) is produced, for example, as follows. In the reaction formula, X ¹ is a halogen atom, and A, Ra ¹ , Ra ² , Rb ¹ , Rb ² , Rc ¹ , Rc ² , Rd ¹ , Rd ² , Re ¹ , Re ² , n ¹ , n ² , ^{o 1, o 2, p 1} , p 2, q 1, q 2 is the same as the description of the formula (1).

(A-1) Step:
In the presence of an acid catalyst, a secondary amine compound (41) and an aldehyde compound (51) are reacted in an organic solvent to form an enamine intermediate (61), and the enamine intermediate (61) is extracted and purified.

The reaction ratio (molar ratio) between the secondary amine compound (41) and the aldehyde compound (51) is preferably 1: 1 to 1: 2.5. If the aldehyde compound (51) is too little, the secondary amine compound (41) remains and purification becomes difficult. When there are too many aldehyde compounds (51), it will become a cost increase.
The reaction temperature is preferably 60 to 120 ° C., and the reaction time is preferably 1 to 5 hours. By setting it as this range, a desired reaction can be efficiently carried out with a relatively simple production facility.

Examples of the acid catalyst include p-toluenesulfonic acid, camphorsulfonic acid, pyridinium-p-toluenesulfonic acid and the like.
0.05-10 mass parts is preferable with respect to 100 mass parts of aldehyde compounds (51), and, as for the addition amount of an acid catalyst, 0.2-4 mass parts is more preferable. If the addition amount of the acid catalyst is less than 0.05 parts by mass, the reactivity between the secondary amine compound (41) and the aldehyde compound (51) may be significantly reduced. If the addition amount of the acid catalyst exceeds 10 parts by mass, it may be difficult to control the reaction between the secondary amine compound (41) and the aldehyde compound (51).

Examples of the organic solvent include toluene, xylene, chlorobenzene, butanol, diethylene glycol dimethyl ether, and the like.
In step (a-1), water is produced as a by-product during the reaction, but this water hinders the reaction, so the produced water is azeotroped with an organic solvent and removed from the reaction system. Is preferred.

(A-2) Process:
In the same manner as in the above step (a-1), the secondary amine compound (42) and the aldehyde compound (52) are reacted in an organic solvent to obtain an enamine intermediate (62), and the enamine intermediate (62). Is extracted and purified.

(B-1) Step:
Enamine intermediate (61) is added to Vilsmeier reagent, and formylation is performed by Vilsmeier reaction. After completion of the reaction, alkaline aqueous solution such as sodium hydroxide aqueous solution is added and hydrolyzed to obtain enamine-aldehyde intermediate (71). obtain.

The reaction ratio (mass ratio) between the enamine intermediate (61) and the Vilsmeier reagent is preferably 1: 1 to 1: 1.5. If there is too little Vilsmeier reagent, the enamine intermediate (61) remains and purification becomes difficult. If there is too much Vilsmeier reagent, the cost increases.
The reaction temperature is preferably 60 to 120 ° C., and the reaction time is preferably 1 to 10 hours. By setting it as this range, a desired reaction can be efficiently carried out with a relatively simple production facility.

Vilsmeier reagent can be prepared by adding N, N-disubstituted formamide and acid chloride in a solvent.
Examples of the solvent include N, N-dimethylformamide, 1,2-dichloroethane and the like.
Examples of the N, N-disubstituted formamide include N, N-dimethylformamide, N-methyl-N-phenylformamide, N, N-diphenylformamide and the like.
Examples of the acid chloride include phosphorus oxychloride, thionyl chloride, oxalyl chloride and the like.

(B-2) Step:
In the same manner as in the above step (b-1), the enamine intermediate (62) is added to the Vilsmeier reagent, the formylation is performed by the Vilsmeier reaction, and after the reaction, an alkaline aqueous solution such as an aqueous sodium hydroxide solution is added, Hydrolysis yields the enamine-aldehyde intermediate (72).

(C) Process:
Compound (8) is reacted with triethyl phosphite to obtain compound (9), and unreacted triethyl phosphite is distilled off under reduced pressure.

  The reaction ratio (molar ratio) between the compound (8) and triethyl phosphite is preferably 1: 2 to 1: 5.0. If there is too little triethyl phosphite, unreacted compound (8) remains and purification becomes difficult. If there is too much triethyl phosphite, the cost increases. The reaction temperature is preferably 120 to 200 ° C., and the reaction time is preferably 2 to 6 hours. By setting it as this range, a desired reaction can be efficiently carried out with a relatively simple production facility.

(D-1) Step:
In the presence of a base, the enamine-aldehyde intermediate (71) and the compound (9) are reacted in an organic solvent to obtain the compound (10), and the compound (10) is extracted and purified.

The reaction ratio (molar ratio) between the enamine-aldehyde intermediate (71) and the compound (9) is preferably 1: 1 to 1: 1.3. When there is too little compound (9), the yield of a compound (10) will decrease. If the amount of compound (9) is too large, the amount of unreacted compound (9) will increase, and purification of compound (10) may be difficult due to side reactions or the like.
The reaction temperature is preferably 15 to 60 ° C., and the reaction time is preferably 1 to 10 hours. By setting it as this range, a desired reaction can be efficiently carried out with a relatively simple production facility.

Examples of the base include metal alkoxides such as sodium methoxide, sodium ethoxide and potassium t-butoxide. A base may be used individually by 1 type and may be used in combination of 2 or more type.
The amount of the base added is preferably 1 to 1.8 mol with respect to 1 mol of the enamine-aldehyde intermediate (71). If the addition amount of the base is less than 1 mol, the reactivity between the enamine-aldehyde intermediate (71) and the compound (9) may be significantly reduced. When the addition amount of the base exceeds 1.8 mol, it may be difficult to control the reaction between the enamine-aldehyde intermediate (71) and the compound (9).

  Examples of the solvent include toluene, xylene, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, dimethyl sulfoxide, N, N-dimethylformamide and the like.

(D-2) Process:
In the same manner as in the above step (d-1), the enamine-aldehyde intermediate (72) and the compound (10) are reacted in an organic solvent in the presence of a base to obtain a compound (1), and the compound (1 ) Is extracted and purified.

  In the steps (d-1) and (d-2), the enamine-aldehyde intermediate (71) and the enamine-aldehyde intermediate (72) may be interchanged.

Moreover, when an enamine intermediate (61) and an enamine intermediate (62) are the same, a compound (1) can be manufactured as follows.
That is, the enamine-aldehyde intermediate (7) and the compound (9) are reacted in an organic solvent in the presence of a base to obtain the compound (1), and the compound (1) is extracted and purified.

Here, Ra is Ra ¹ and Ra ² , Rb is Rb ¹ and Rb ² , Rc is Rc ¹ and Rc ² , Rd is Rd ¹ and Rd ² , Re is Re ¹ and Re ² , n is n ¹ and n ² , O represents o ¹ and o ² , p represents p ¹ and p ² , q represents q ¹ and q ² , respectively.
The enamine-aldehyde intermediate (7) is a compound obtained by using the enamine intermediate (61) or the enamine intermediate (62) as a raw material and passing through the step (b-1) or the step (b-2). is there.

The reaction ratio (molar ratio) between the enamine-aldehyde intermediate (7) and the compound (9) is preferably 2: 1 to 2.5: 1. If there is too little enamine-aldehyde intermediate (7), the yield of compound (1) will decrease. When there are too many enamine-aldehyde intermediates (7), unreacted enamine-aldehyde intermediates (7) will increase, and there exists a possibility that the refinement | purification of a compound (1) may become difficult by side reaction etc.
The reaction temperature and reaction time in step (d) are the same as in step (d-1). Moreover, as a kind of the base and solvent used at (d) process, the thing similar to (d-1) process is mentioned. In addition, the addition amount of the base is preferably 2 to 3.6 mol with respect to 1 mol of the enamine-aldehyde intermediate (7).

In the compound (1) described above, the Ra ¹ and Ra ^{2 in} the above general formula (1) are specified as an alkyl group having 1 to 12 carbon atoms substituted with at least one fluorine atom, whereby aryl is added to the whole molecule. The group becomes a twisted structure, and as a result, the solubility in a solvent is improved. Therefore, if it is a compound (1), it can have the outstanding solubility and hole transport ability. Further, since the compound (1) is excellent in solubility, it is difficult to crystallize at the time of producing the electrophotographic photosensitive member, and an electrophotographic photosensitive member having excellent electric characteristics can be obtained.
Here, the “solvent” is a solvent used when preparing a coating solution by dissolving the components constituting the photosensitive layer, which will be described in detail later. Specifically, an aromatic hydrocarbon, Examples thereof include halogenated hydrocarbons and ethers.

In addition, the compound (1) has a steric hindrance by being identified as an alkyl group having 1 to 12 carbon atoms substituted with at least one fluorine atom as Ra ¹ and Ra ^{2 in} the above general formula (1). Compatibility with the resin is improved. In addition, since the conjugation extends to the molecular end, charge mobility can be increased. Therefore, the electrophotographic photoreceptor produced using the compound (1) as a hole transport agent suppresses the generation of cracks in the photosensitive layer even when exposed to a liquid developer for a long time, and the elution amount of the hole transport agent is reduced. It can be reduced, and it has excellent solvent resistance and electrical characteristics.
Here, the “solvent” of “solvent resistance” is a liquid (toner dispersion medium) constituting the liquid developer, and examples thereof include hydrocarbon solvents.

  Furthermore, the compatibility of the compound (1) with the binder resin is improved when A in the general formula (1) is a specific substituent. Accordingly, in the electrophotographic photoreceptor produced using the compound (1) as a hole transport agent, the compound (1) is uniformly dispersed in the photosensitive layer, so that the durability is improved and the charge mobility is increased. Electrical characteristics are improved.

By the way, charge transport agents can be broadly classified into hole transport agents and electron transport agents.
In the present invention, the compound (1) described above is used as a hole transporting agent, but other hole transporting agents and electron transporting agents may be used in combination.

  Among other charge transport agents, examples of the hole transport agent include benzidine compounds, phenylenediamine compounds, naphthylenediamine compounds, phenanthrylenediamine compounds, oxadiazole compounds, styryl compounds, and carbazole compounds. , Pyrazoline compounds, hydrazone compounds, triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, butadiene compounds Compound, pyrene-hydrazone compound, acrolein compound, carbazole-hydrazone compound, quinoline-hydrazone compound, stilbene compound, stilbene-hydrazone compound, and dipheni Njiamin based compounds. A hole transport agent may be used individually by 1 type, and may use 2 or more types together.

  On the other hand, as electron transport agents, quinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3,4,5,7-tetranitro-9-fluorenone derivatives, dinitroanthracene derivatives, dinitroacridine derivatives, nitroant Araquinone derivatives, dinitroanthraquinone derivatives, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, dibromomaleic anhydride, etc. Is mentioned. An electron transfer agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these electron transfer agents, since the electron acceptability and the matching with the charge generating agent are excellent, and an electrophotographic photoreceptor excellent in sensitivity characteristics and durability can be obtained, the compounds (11-1) to (11- 4) is particularly preferred.

(Binder resin)
As binder resin, polycarbonate resin such as bisphenol Z type, bisphenol ZC type, bisphenol C type and bisphenol A type, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer Polymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer , Alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl acetal resins, polyvinyl butyral resins, polyether resins, etc .; silicone resins, epoxy resins Phenolic resins, urea resins, thermosetting resins such as melamine resin, epoxy acrylate, urethane - photocurable resins such as acrylate. Binder resin may be used individually by 1 type, and may use 2 or more types together.

  Among these binder resins, the compounds (12-1) to (12-3) are particularly preferable from the viewpoint of the film strength of the photosensitive layer and the compatibility with the hole transporting agent and the electron transporting agent.

(Other)
The photosensitive layer may contain known additives as long as the electrophotographic characteristics are not affected. Examples of additives include antioxidants, light stabilizers, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, Examples include dispersion stabilizers, waxes, acceptors, donors, and the like.
In order to improve the sensitivity of the photoreceptor layer, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.
Specific examples of these additives include biphenyl compounds (13-1). By adding a biphenyl compound, the generation of cracks can be suppressed and the photosensitive layer can be prevented from cracking.

<Structure of photosensitive layer>
The photosensitive layer may have a single layer structure containing the above-described charge generating agent, charge transporting agent, and binder resin in the same layer, and includes a charge generating layer containing at least the charge generating agent, the charge transporting agent, and the binding agent. A laminated structure having a charge transport layer containing a resin may be used.
The order of stacking the charge generation layer and the charge transport layer in the multilayered photosensitive layer is not particularly limited. However, since the charge generation layer is thinner than the charge transport layer, it is preferable to provide a charge transport layer on the charge generation layer in order to protect the charge generation layer.
Here, in the present invention, an electrophotographic photosensitive member having a photosensitive layer having a single-layer structure is referred to as a “single-layer type electrophotographic photosensitive member”, and an electrophotographic photosensitive member having a laminated structure is referred to as a “multi-layered electrophotographic photosensitive member”. And

(Photosensitive layer with a single layer structure)
The content of the charge generating agent is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the binder resin.
20-500 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of a hole transport agent, 30-200 mass parts is more preferable.
5-100 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of an electron transport agent, 10-80 mass parts is more preferable.
The thickness of the photosensitive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm.

(Photosensitive layer with a laminated structure)
The charge generation layer includes the charge generation agent and the binder resin described above. In addition, a known additive may be contained as long as the electrophotographic characteristics are not adversely affected.
The content of the charge generation agent in the charge generation layer is preferably 5 to 1000 parts by mass, more preferably 30 to 500 parts by mass with respect to 100 parts by mass of the binder resin.
The thickness of the charge generation layer is preferably from 0.01 to 5 μm, and more preferably from 0.1 to 3 μm.

The charge transport layer includes the charge transport agent and the binder resin described above. In addition, a known additive may be contained as long as the electrophotographic characteristics are not adversely affected.
10-500 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of the hole transport agent of a charge transport layer, 25-200 mass parts is more preferable.
When the electron transport agent is contained in the charge transport layer, the content of the electron transport agent is preferably 5 to 200 parts by weight, and more preferably 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin.
The thickness of the charge transport layer is preferably 2 to 100 μm, and more preferably 5 to 50 μm.

<Other layers>
In the electrophotographic photoreceptor of the present invention, an intermediate layer may be interposed between the conductive substrate and the photosensitive layer. The electrophotographic photosensitive member with the intermediate layer interposed can effectively suppress the occurrence of leakage. Further, a protective layer may be provided on the photosensitive layer.
The intermediate layer contains inorganic particles. By containing the inorganic particles, an increase in resistance can be suppressed by flowing a current smoothly when the electrophotographic photosensitive member is exposed while suppressing the occurrence of leakage. Examples of the inorganic particles include metals and metal oxides. Specific examples include aluminum, iron, copper, titanium oxide, silica, alumina, zirconium oxide, tin oxide, zinc oxide, and indium oxide. Among these, titanium oxide is preferable. In particular, rutile type titanium oxide is preferable from the viewpoint of imparting appropriate insulating properties.

  The intermediate layer contains a binder resin in addition to the inorganic particles described above. As the binder resin, one or more of the binder resins exemplified above in the description of the photosensitive layer can be selected and used.

The intermediate thickness is preferably from 0.1 to 10 μm, more preferably from 0.5 to 5 μm.
10-1000 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of the inorganic particle in an intermediate | middle layer, 30-400 mass parts is more preferable.

<Production of electrophotographic photoreceptor>
The electrophotographic photoreceptor of the present invention can be produced, for example, as follows.
(Single layer type electrophotographic photoreceptor)
A coating solution in which a hole transporting agent, a charge generating agent, a binder resin and, if necessary, an electron transporting agent are dissolved or dispersed in a solvent is applied onto a conductive substrate, dried, and then exposed on the conductive substrate. An electrophotographic photosensitive member having a layer formed thereon is prepared.
The coating liquid is prepared by dissolving or dispersing each component in a solvent using a roll mill, a ball mill, an attritor, a paint shaker, an ultrasonic disperser or the like.

  Examples of the solvent include alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, dichloroethane, Halogenated hydrocarbons such as chloroform, carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide and the like. A solvent may be used individually by 1 type and may be used in mixture of 2 or more types.

Examples of the coating method include known methods such as dip coating, spray coating, spin coating, and bar coating.
Examples of the drying device include a high-temperature dryer and a vacuum dryer. The drying temperature is preferably 60 to 150 ° C.
An intermediate layer may be formed on the conductive substrate before forming the photosensitive layer. In this case, each component contained in the intermediate layer is dissolved or dispersed in the above-mentioned solvent to prepare an intermediate layer coating solution, and the coating solution is applied onto a conductive substrate and dried to form the intermediate layer. Good.
The method for preparing the coating solution, the coating method, the drying conditions, and the like are the same as those for forming the photosensitive layer.

(Laminated electrophotographic photoreceptor)
First, each component contained in the charge generation layer is dissolved or dispersed in the solvent described above to prepare a charge generation layer coating solution. Similarly, each component contained in the charge transport layer is dissolved or dispersed in the solvent described above to prepare a charge transport layer coating solution.
Next, the above-described coating liquids are sequentially applied and dried on the conductive substrate to form a charge generation layer and a charge transport layer.
The order of application and drying of each coating solution is not particularly limited. Moreover, the preparation method, coating method, drying conditions, etc. of the coating solution are the same as in the case of forming the photosensitive layer of the single-layer type electrophotographic photoreceptor.
Further, as in the case of the single-layer type electrophotographic photoreceptor, an intermediate layer may be formed on the conductive substrate before forming the charge generation layer and the charge transport layer.

The electrophotographic photoreceptor of the present invention thus obtained is produced using the specific compound (1) as a hole transporting agent, which is excellent in solubility in a solvent and compatibility with a binder resin. A part of the charge transfer agent (especially the hole transfer agent) can be suppressed from being crystallized at the time of production, and is hardly precipitated. Therefore, the electrophotographic photosensitive member of the present invention is excellent in electrical characteristics such as sensitivity.
The electrophotographic photoreceptor of the present invention can maintain electrical characteristics even when used in a high temperature and high humidity environment.
Furthermore, since the electrophotographic photosensitive member of the present invention has good compatibility with the binder resin, the hole transport agent is hardly eluted and is excellent in solvent resistance and durability.

[Image forming apparatus]
<First embodiment>
FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus of the present invention. The image forming apparatus 10 includes an electrophotographic photosensitive member 11, and a charging unit 12, an exposing unit 13, a developing unit 14, a transfer unit 15, and a cleaning unit 16 around the electrophotographic photosensitive member 11.

The electrophotographic photoreceptor 11 is the electrophotographic photoreceptor of the present invention, and a photosensitive layer having a single layer structure or a laminated structure is laminated on a drum-shaped conductive substrate.
The charging means 12 is a means for charging the surface of the electrophotographic photosensitive member 11, and examples thereof include a corona charging device, a charging roller, and a charging brush.
The exposure unit 13 is a unit that exposes the surface of the electrophotographic photosensitive member 11 to form an electrostatic latent image.
The developing unit 14 is a unit that develops an electrostatic latent image as a toner image using toner.
The transfer unit 15 is a unit that transfers the toner image from the electrophotographic photosensitive member 11 to a transfer target (not shown).
The cleaning means 16 is means for removing paper dust and the like adhering to the electrophotographic photosensitive member 11, and examples thereof include an elastic blade and a fur brush.

In general, the image forming apparatus is often provided with a charge eliminating means for removing the charge on the surface of the electrophotographic photosensitive member.
However, since the image forming apparatus of the present invention includes the electrophotographic photosensitive member of the present invention, it is difficult for charges generated by exposure to accumulate inside the photosensitive layer. For this reason, even if the static eliminating means is not provided, the surface potential difference between the exposed portion and the non-exposed portion is small when the photoreceptor is charged in the next cycle. Therefore, it is not necessary to provide a static elimination means such as a static elimination lamp, and the manufacturing cost can be reduced.
In the image forming apparatus of the present invention, since the photosensitive layer has sufficient film strength and leakage resistance, a charging roller can be used as the charging means. By using a charging roller, the discharge of active gas such as ozone and nitrogen oxide generated from the charging means is suppressed, and the photosensitive layer of the electrophotographic photosensitive member is prevented from being deteriorated by the active gas, and the office environment is taken into consideration. You can make a design.

In the image forming apparatus described above, the crystallization of the charge transport agent in the charge transport layer is suppressed and the electrophotographic photoreceptor of the present invention having excellent electrical characteristics is used. High-quality images can be obtained with less image fogging. In addition, since the electrophotographic photosensitive member of the present invention can maintain electrical characteristics even in a high temperature and high humidity environment, a high quality image can be obtained.
Examples of such an image forming apparatus include a copying machine, a facsimile, and a laser beam printer.

<Second Embodiment>
FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus for wet development according to the present invention. The image forming apparatus 20 for wet development includes an electrophotographic photosensitive member 21 of the present invention, a charging unit 22, an exposing unit 23, a developing unit 24, a transfer unit 25, and a cleaning device around the electrophotographic photosensitive member 21. Means 26 are provided. As the developer, a liquid developer in which toner is dispersed in a hydrocarbon solvent is used. The charging unit 22, the exposure unit 23, the developing unit 24, the transfer unit 25, and the cleaning unit 26 play the same role as the units described in the first embodiment.

Here, the image forming method will be described with reference to FIG.
The electrophotographic photosensitive member 21 rotates at a constant speed in the direction of the arrow, and the electrophotographic process is performed on the surface of the electrophotographic photosensitive member 21 in the following order. More specifically, the electrophotographic photosensitive member 21 is charged entirely by the charging unit 22, and then the print pattern is exposed by the exposure unit 23. Next, the developing unit 24 develops toner corresponding to the print pattern, and the transfer unit 25 transfers the toner to a transfer material (paper) 27. Finally, the excess toner remaining on the electrophotographic photosensitive member 21 is scraped off by the cleaning unit 26 and the electrophotographic photosensitive member 21 is neutralized by the neutralizing unit 28.

  Here, the liquid developer 24a in which the toner is dispersed is conveyed by the developing roller 24b, and the toner is attracted onto the surface of the electrophotographic photosensitive member 21 by applying a predetermined developing bias. 21 will be developed. Further, the solid content concentration in the liquid developer 24a is preferably set to a value in the range of 5 to 25% by weight, for example. Further, examples of the hydrocarbon solvent used in the liquid developer 24a include isoparaffin and normal paraffin.

By the way, in the case of an image forming apparatus for wet development using a liquid developer, components constituting the electrophotographic photosensitive member, particularly a hole transport agent, are likely to elute, and the electrical characteristics of the electrophotographic photosensitive member are liable to deteriorate. For this reason, the characteristics of the formed image are likely to deteriorate.
However, since the image forming apparatus for wet development according to the present invention includes the electrophotographic photosensitive member according to the present invention, it is excellent in durability, has good solvent resistance, and does not easily elute the hole transport agent. The electrical characteristics of the photoreceptor can be maintained. Therefore, excellent image characteristics can be maintained for a long time.

In the image forming apparatus for wet development described above, since the crystallization of the charge transport agent in the charge transport layer is suppressed and the electrophotographic photosensitive member of the present invention having excellent electrical characteristics is used, crystallization is the cause. Image defects, image fogging and the like are unlikely to occur, and a high-quality image can be obtained. In addition, since the electrophotographic photosensitive member of the present invention can maintain electrical characteristics even in a high temperature and high humidity environment, a high quality image can be obtained.
Moreover, since it is excellent in durability and solvent resistance is good and the hole transport agent is hardly eluted, it is possible to maintain excellent image characteristics over a long period of time.

[Synthesis of hole transport agent]
<Synthesis of Compound (1-1)>
(A) Process:
In a reaction vessel, p-toluenesulfonic acid, secondary amine compound (4-1) 133.6 g (0.5 mol), aldehyde compound (5-1) 137.37 g (0.7 mol), toluene, and toluene were added. The mixture was stirred for 4 hours while being heated at, and reacted while removing water from the system azeotropically with water and toluene. After cooling to room temperature, the enamine intermediate (6-1) was extracted and purified.

(B) Process:
First, N-dimethylformamide and phosphorus oxychloride were added to N, N-dimethylformamide to prepare a Vilsmeier reagent.
To the obtained Vilsmeier reagent, 133.6 g (0.3 mol) of enamine intermediate (6-1) was added, stirred for 6 hours while heating at 80 ° C., subjected to formylation by Vilsmeier reaction, and after completion of the reaction, A sodium oxide aqueous solution was added and hydrolyzed to obtain an enamine-aldehyde intermediate (7-1).

(C) Process:
In a reaction vessel, 35.0 g (0.2 mol) of the compound (8-1) and 99.6 g (0.6 mol) of triethyl phosphite were added and stirred for 3 hours while heating at 30 ° C. After cooling to room temperature, excess triphosphorous acid triethyl ester was distilled off under reduced pressure to obtain compound (9-1).

(D) Process:
Sodium methoxide, 71.0 g (0.15 mol) of enamine-aldehyde intermediate (7-1), 18.9 g (0.05 mol) of compound (9-1), and tetrahydrofuran are placed in a reaction vessel and heated at 30 ° C. The mixture was stirred for 5 hours while being reacted. After cooling to room temperature, the compound (1-1) was extracted and purified.

<Synthesis of Compound (1-2)>
In the step (c), the compound (8-1) was synthesized in the same manner as the compound (1-1) except that 50.2 g (0.2 mol) of the compound (8-2) was used instead of the compound (8-1). Compound (1-2) was obtained.

<Synthesis of Compound (1-3)>
In the step (a), synthesis was performed in the same manner as in the compound (1-1) except that 158.6 g (0.5 mol) of the compound (4-2) was used instead of the compound (4-1). Compound (1-3) was obtained.

<Synthesis of Compound (1-4)>
(C) In the step, compound (8-1) was synthesized in the same manner as compound (1-1) except that 45.0 g (0.2 mol) of compound (8-3) was used instead of compound (8-1). Compound (1-4) was obtained.

<Synthesis of Compound (1-5)>
In the step (c), the compound (8-1) was synthesized in the same manner as the compound (1-1) except that 35.0 g (0.2 mol) of the compound (8-4) was used instead of the compound (8-1). Compound (1-5) was obtained.

<Synthesis of Compound (14-1)>
In the step (a), the compound (4-1) was synthesized in the same manner as the compound (1-1) except that 130.7 g (0.5 mol) of the compound (4-3) was used instead of the compound (4-1). Compound (14-1) was obtained.

<Synthesis of Compound (14-2)>
In the step (a), synthesis was performed in the same manner as in the compound (1-1) except that 91.6 g (0.2 mol) of the compound (4-4) was used instead of the compound (4-1). Compound (14-2) was obtained.

[Synthesis of Charge Generator (Titanyl Phthalocyanine)]
(Pigmentation pretreatment)
In a flask purged with argon, 22 g of o-phthalonitrile, 25 g of titanium tetrabutoxide, 2.28 g of urea and 300 g of quinoline were added, and the temperature was raised to 150 ° C. while stirring.
Next, while evaporating the vapor generated from the reaction system, the temperature was raised to 215 ° C. while distilling out of the system, and the mixture was further stirred for 2 hours while maintaining this temperature.
After completion of the reaction, when the reaction mixture is cooled to 150 ° C., the reaction mixture is taken out from the flask and filtered through a glass filter. The obtained solid is washed successively with N, N-dimethylformamide and methanol, and then dried in vacuo. 24 g of a violet solid was obtained.

10 g of the obtained blue-violet solid was added to 100 mL of N, N-dimethylformamide, heated to 130 ° C. with stirring, and stirred for 2 hours.
Next, after 2 hours had elapsed, heating was stopped, and after cooling to 23 ± 1 ° C., stirring was also stopped. In this state, the liquid was allowed to stand for 12 hours for stabilization treatment.
The stabilized supernatant was filtered off with a glass filter, and the resulting solid was washed with methanol and then vacuum dried to obtain 9.83 g of a crude crystal of a titanyl phthalocyanine compound.

(Pigmentation treatment)
5 g of the crude crystal of the obtained titanyl phthalocyanine compound was dissolved in 100 mL of concentrated sulfuric acid.
Next, this solution was added dropwise to ice-cooled water, stirred at room temperature for 15 minutes, and further allowed to stand at 23 ± 1 ° C. for 30 minutes for recrystallization, and the supernatant was separated.
Next, the supernatant is filtered off with a glass filter, and the obtained solid is washed with water until the washing solution becomes neutral. Then, without drying, it is dispersed in 200 mL of chlorobenzene and heated to 50 ° C. And stirred for 10 hours.
The supernatant was filtered off with a glass filter, and the obtained solid was vacuum-dried at 50 ° C. for 5 hours to obtain 4.1 g of crystals (blue powder) of titanyl phthalocyanine (3-2).

  Using the obtained titanyl phthalocyanine (3-2), CuKα characteristic X-ray diffraction spectrum measurement and differential scanning calorimetry were performed immediately after synthesis and after immersion in 1,3-dioxolane or tetrahydrofuran for 7 days, respectively. As a result, in the measurement of the CuKα characteristic X-ray diffraction spectrum, it was confirmed that no peaks were generated at Bragg angles 2θ ± 0.2 ° = 7.4 ° and 26.2 ° in any case. In the differential scanning calorimetry, in any case, when the temperature was raised to 400 ° C., one peak was observed at 296 ° C. in addition to the peak near 90 ° C. accompanying vaporization of adsorbed water.

[Test 1: Laminated electrophotographic photoreceptor]
<Example 1>
(Production of multilayer electrophotographic photoreceptor)
Forming an intermediate layer;
Using a bead mill, titanium oxide (Titanium oxide STE-02 (number average primary particle diameter 10 nm) manufactured by Teika Co., Ltd. was surface-treated with alumina and silica and then surface-treated with methyl hydrogen polysiloxane while being wet-dispersed) 300 Part by mass and 100 parts by mass of a copolymerized polyamide resin (“Daiamide X4585” manufactured by Daicel Degussa) were dispersed in 100 parts by mass of ethanol and 200 parts by mass of butanol and mixed for 5 hours. Then, it filtered with a 5-micrometer filter and prepared the coating liquid for intermediate | middle layers.
One end of an aluminum drum-shaped substrate having a diameter of 30 mm and a total length of 238.5 mm as a conductive substrate is immersed in the obtained intermediate layer coating solution at a rate of 5 mm / sec. It was coated on a conductive substrate. Then, it heat-processed on 130 degreeC and the conditions for 30 minutes, and formed the intermediate | middle layer with a film thickness of 1.5 micrometers.

Formation of a charge generation layer;
Using a bead mill, 200 parts by mass of titanyl phthalocyanine (3-2) previously synthesized as a charge generating agent, 100 parts by mass of polyvinyl butyral resin (manufactured by Denki Kagaku Kogyo Co., Ltd., “Denka Butyral 6000C”) as a binder resin, and dispersion As a medium, 4000 parts by mass of propylene glycol monomethyl ether and 4000 parts by mass of tetrahydrofuran were dispersed and mixed for 2 hours to prepare a coating solution for a charge generation layer.
The obtained coating solution for charge generation layer was filtered through a 3 μm filter, then applied on the intermediate layer prepared above by dip coating, dried at 50 ° C. for 5 minutes, and a film thickness of 0.3 μm. The charge generation layer was formed.

Formation of a charge transport layer;
Using a roll mill, 70 parts by mass of the compound (1-1) as a hole transport agent, 5 parts by mass of the compound (11-1) as an electron transport agent, and meta-terphenyl (13-1) 5 of a biphenyl derivative as an additive 100 parts by mass of polycarbonate resin (12-1) having a viscosity average molecular weight of 50,000 as a binder resin and 5 parts by mass of BHT (2,6-di-tert-butyl-4-cresol) as an antioxidant Then, 600 parts by mass of tetrahydrofuran as a solvent was mixed and dissolved over 24 hours to prepare a charge transport layer coating solution.
The obtained charge transport layer coating solution was applied onto the charge generation layer in the same manner as the charge generation layer coating solution, and dried at 130 ° C. for 30 minutes to form a charge transport layer having a thickness of 20 μm. Type electrophotographic photosensitive member was produced.

(Evaluation 1: Evaluation of sensitivity)
First, the developing means is removed from the imaging unit in a printer (Oki Data Corporation, "c5800n") that employs a charging roller system and employs a negatively charged reversal development process that does not have a charge eliminating lamp, and a potential measuring device is installed there. The imaging unit for measuring the potential was installed. Such a potential measuring device has a configuration in which a potential measuring probe is arranged with respect to the developing position of the imaging unit. Further, such a potential measuring probe was disposed with respect to the center in the axial direction of the electrophotographic photosensitive member, and the distance between the potential measuring probe and the surface of the electrophotographic photosensitive member was 5 mm.
Next, the obtained multilayer electrophotographic photoreceptor is mounted on the above-described potential measurement imaging unit, negatively charged, and solid black in a normal temperature and humidity environment (temperature 20 ° C., relative humidity 50%). Exposure corresponding to an image was performed, and the potential of the exposed portion was measured to obtain sensitivity (V). The obtained results are shown in Table 1. In addition, although the measured value of the obtained charging potential (V) and sensitivity (V) was a negative value, in Table 1, the absolute value (positive value) is described.

(Evaluation 2: Evaluation of exposure memory potential)
In the same manner as the sensitivity evaluation, the obtained multilayer electrophotographic photosensitive member is mounted on the above-described potential measurement imaging unit, and the electrophotographic photosensitive member of the first round (95 mm length) is mounted under the same environment. On the other hand, exposure corresponding to a solid black image of 65 mm was performed (exposed portion), and the remaining 30 mm was not exposed (non-exposed portion). Next, the entire electrophotographic photoreceptor on the second round was not exposed. Next, the surface potential V ₀ b (V) in the second turn of the portion corresponding to the exposed portion of the first turn and the surface potential V ₀ (V) in the second turn of the portion corresponding to the non-exposed portion of the first turn. And the absolute value | V ₀ −V ₀ b | (V) of this potential difference was calculated to obtain the exposure memory potential (V). The obtained results are shown in Table 1.

(Evaluation 3: Evaluation of image cover)
The obtained multilayer electrophotographic photosensitive member was mounted on a printer (Oki Data Corporation, “c5800n”), and 20 blank paper images were printed in a high temperature and high humidity environment (temperature 35 ° C., relative humidity 85%). For the tenth blank paper image, the density FD ₁ value (−) was measured using a Macbeth reflection densitometer (“SPM-50” manufactured by Gretag Macbeth). Similarly, density FD ₀ value in the blank image that has not yet been output (-) is measured, density FD ₁ value (-) from the density FD ₀ value (-) draw, it was FD value (head value). The results are shown in Table 1.

<Examples 2-9, Comparative Examples 1-2>
Example 1 except that a charge generation layer coating solution was prepared using the charge generation agent shown in Table 1 and a charge transport layer coating solution was prepared using the hole transport agent and binder resin shown in Table 1. In the same manner as above, a multilayer electrophotographic photosensitive member was prepared and evaluated. The results are shown in Table 1.

As is clear from Table 1, the multilayer electrophotographic photoreceptor obtained in the examples had a lower exposure memory and excellent electrical characteristics than the multilayer electrophotographic photoreceptor obtained in the comparative example. In addition, a high-quality image can be formed with a low FD value.
When the charge transport layer coating solution prepared in Example 9 was allowed to stand for 30 days, the hole transport agent crystallized and precipitated. In the charge transport layer coating solutions prepared in other Examples, the hole transport agent was difficult to crystallize even when left for a long period of time.

The multilayer electrophotographic photoreceptor obtained in Comparative Example 1 had a higher exposure memory and a lower sensitivity than the Examples. Moreover, the fogging value was high.
On the other hand, in the laminated electrophotographic photoreceptor obtained in Comparative Example 2, the hole transport agent crystallized and deposited on the surface of the photoreceptor when the charge transport layer coating solution was applied. And the FD value could not be measured. Therefore, the evaluation test was not performed.

[Test 2: Single-layer type electrophotographic photosensitive member]
<Example 10>
(Production of single layer type electrophotographic photoreceptor)
Forming an intermediate layer;
An intermediate layer having a film thickness of 1.5 μm was formed on the conductive substrate in the same manner as in Example 1 except that an aluminum drum-shaped substrate having a diameter of 30 mm and a total length of 247.5 mm was used as the conductive substrate.

Formation of a photosensitive layer;
In an ultrasonic disperser, 3 parts by mass of x-type metal-free phthalocyanine (3-1) as a charge generator, 50 parts by mass of compound (1-1) as a hole transport agent, and compound (11-1 as an electron transport agent) ) 40 parts by mass, 3 parts by mass of meta-terphenyl (13-1) as a biphenyl derivative as an additive, 100 parts by mass of a polycarbonate resin (12-1) having a viscosity average molecular weight of 30,500 as a binder resin, and a solvent After containing 600 parts by mass of tetrahydrofuran, the mixture was dissolved for 10 minutes to prepare a coating solution for photosensitive layer.
Next, the obtained coating solution for forming a photosensitive layer is applied on the intermediate layer by a dip coating method, and then dried with hot air at 130 ° C. for 40 minutes to form a photosensitive layer having a thickness of 25 μm. A layer type electrophotographic photosensitive member was produced.

(Evaluation 4: Evaluation of sensitivity)
An imaging unit for potential measurement was prepared using a printer (“FS-920” manufactured by Kyocera Mita Co., Ltd.), and the obtained single layer type electrophotographic photosensitive member was mounted. Moreover, while removing the static elimination lamp, the light quantity at the time of exposure was set to 1.0 μJ / cm ² . Other than that, it evaluated similarly to the sensitivity evaluation in Example 1 (evaluation 1). The obtained results are shown in Table 2.

(Evaluation 5: Evaluation of exposure memory potential)
In the same manner as in Evaluation 4, the obtained single-layer electrophotographic photosensitive member was evaluated in the same manner as in the evaluation of the exposure memory potential (Evaluation 2) in Example 1 except that the obtained single-layer electrophotographic photosensitive member was mounted on the above-described potential measurement imaging unit. . The obtained results are shown in Table 2.

(Evaluation 6: Evaluation of image covering)
Evaluation was conducted in the same manner as in the image fogging evaluation (Evaluation 3) in Example 1 except that the obtained single-layer electrophotographic photosensitive member was mounted on a printer (“FS-920” manufactured by Kyocera Mita Co., Ltd.). The obtained results are shown in Table 2.

<Examples 11 to 21, Comparative Examples 3 to 4>
A single-layer electrophotographic photosensitive member was prepared in the same manner as in Example 10 except that the coating solution for photosensitive layer was prepared using the charge generating agent, hole transporting agent, electron transporting agent and binder resin shown in Table 2. Prepared and evaluated. The results are shown in Table 2.
In Example 17, 3 parts by mass of titanyl phthalocyanine (4-2) as a charge generating agent and C.I. I. 2 parts by mass of Pigment Yellow 93 (PY93) was used.

  As is apparent from Table 2, the single layer type electrophotographic photosensitive member obtained in the example had a lower exposure memory and excellent electrical characteristics than the single layer type electrophotographic photosensitive member obtained in the comparative example. . In addition, a high-quality image can be formed with a low FD value.

On the other hand, the single layer type electrophotographic photosensitive member obtained in Comparative Example 3 had a sensitivity, exposure memory, and the like because the hole transporting agent crystallized and deposited on the surface of the photosensitive member when the photosensitive layer coating solution was applied. And the FD value could not be measured. Therefore, the evaluation test was not performed.
The single layer type electrophotographic photosensitive member obtained in Comparative Example 4 had higher exposure memory and lower sensitivity than the Examples. Moreover, the fogging value was high. When the photosensitive layer coating solution prepared in Comparative Example 4 was allowed to stand for 30 days, the hole transporting agent crystallized and precipitated.

[Test 3]
<Example 22>
(Production of single-layer electrophotographic photoreceptor for wet development)
Formation of a photosensitive layer;
In an ultrasonic disperser, 4 parts by mass of an x-type metal-free phthalocyanine (3-1) as a charge generating agent, 40 parts by mass of a compound (1-1) as a hole transporting agent, and a naphthoquinone derivative (11- 3) 50 parts by mass, 100 parts by mass of a polycarbonate resin (12-2) having a viscosity average molecular weight of 50,000 as a binder resin, and dimethyl silicone oil (“KF-96-50CS” manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent ) After containing 0.1 part by mass and 750 parts by mass of tetrahydrofuran as a solvent, the mixture was dissolved for 1 hour to prepare a coating solution for a photosensitive layer.
Next, the obtained photosensitive layer forming coating solution was applied to the entire outer surface of the anodized aluminum base tube having a diameter of 30 mm, a total length of 254 mm, and a thickness of 5 μm. Thereafter, it was dried with hot air at 130 ° C. for 30 minutes to form a photosensitive layer having a film thickness of 22 μm, and a single layer type electrophotographic photosensitive member for wet development was produced.

(Evaluation 7: Evaluation of sensitivity)
Using a drum sensitivity tester (manufactured by GENTEC), the obtained single-layer electrophotographic photosensitive member for wet development was charged to 700V. Next, monochromatic light (half width: 20 nm, light amount: 1.0 μJ / cm ² ) having a wavelength of 780 nm extracted from the light of the halogen lamp using a hand pulse filter was exposed. The potential after the elapse of 330 milliseconds after the exposure was measured and used as the initial sensitivity (V).
Further, the obtained single-layer electrophotographic photosensitive member for wet development was placed in a hydrocarbon solvent (“Isopar G” manufactured by Exxon Chemical Co., Ltd.) used as a toner dispersion medium of a wet developer at a temperature of 25 ° C. And soaking for 2000 hours. Then, take out the monolayer type electrophotographic photoreceptor for wet development from the hydrocarbon solvent, measure the sensitivity in the same way, calculate the difference between the initial sensitivity and the sensitivity after immersion in the hydrocarbon solvent, change the sensitivity (V). The obtained results are shown in Table 3.

(Evaluation 8: Evaluation of solvent resistance)
The obtained single-layer electrophotographic photosensitive member for wet development is immersed in a hydrocarbon solvent (“Isopar G” manufactured by Exxon Chemical Co., Ltd.) so that the entire surface of the photosensitive layer is immersed. Soaked. On the other hand, the concentration of the hole transport agent was changed and dissolved in a hydrocarbon solvent (Exxon Chemical Co., “Isopar G”). In this state, the absorbance at the absorption peak wavelength from the ultraviolet region to the visible region was measured, and a concentration-absorbance calibration curve for the hole transport agent was prepared in advance.
Next, for a single layer type electrophotographic photoreceptor for wet development immersed in a hydrocarbon solvent (Exxon Chemical Co., Ltd., “Isopar G”), an absorption measurement is performed from the ultraviolet region to the visible region, and in light of the calibration curve, The elution amount of the hole transport agent was calculated from the absorbance value at the absorption peak wavelength from the ultraviolet region to the visible region of the hole transport agent. The obtained results are shown in Table 3.

(Evaluation 9: Appearance evaluation)
The appearance of the single-layer electrophotographic photoreceptor for wet development after the solvent resistance evaluation (Evaluation 8) was visually observed for the presence or absence of cracks, and the appearance was evaluated according to the following criteria. Table 4 shows the obtained results.
A: No change in appearance is observed.
○: No significant change in appearance is observed.
Δ: A slight change in appearance is observed.
X: A remarkable change in appearance is observed.

As is apparent from Table 3, the single layer type electrophotographic photosensitive member for wet development obtained in the Examples has an initial sensitivity of 105 V and an elution amount of the hole transport agent of 4.5 × 10 ⁻⁷ g. / Cm ³ . In addition, the electrophotographic photoreceptor after immersion in a hydrocarbon solvent showed no change in appearance.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus for wet development according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Image forming apparatus, 11 Electrophotographic photosensitive member, 12: Charging means, 13: Exposure means, 14: Developing means, 15: Transfer means, 20: Image forming apparatus for wet development, 21 Electrophotographic photosensitive member, 22: Charging Means: 23: exposure means, 24: developing means, 25: transfer means.

Claims (7)

In an electrophotographic photoreceptor in which a photosensitive layer containing a charge generating agent, a charge transporting agent including a hole transporting agent, and a binder resin is formed on a conductive substrate,
The electrophotographic photoreceptor, wherein the photosensitive layer contains an enamine compound represented by the following general formula (1) as the hole transport agent.

In the formula (1), A is a divalent organic group containing an aromatic ring, and Ra ¹ and Ra ² are the same or different and each is an alkyl group having 1 to 12 carbon atoms substituted with at least one fluorine atom. Rb ¹ , Rb ² , Rc ¹ , Rc ² , Rd ¹ , Rd ² , Re ¹ , Re ² are the same or different and are each an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 30 carbon atoms , An alkenyl group having 6 to 30 carbon atoms, or —OR ¹ (where R ¹ is an alkyl group having 1 to 10 carbon atoms, a perfluoroalkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms). N ¹ , n ² , q ¹ , and q ² representing the number of repeating substituents are integers of 0 to 4, and o ¹ , o ² , p ¹ , and p ² are integers of 0 to 5. . The electrophotographic photosensitive member according to claim ¹ , wherein Ra ¹ and Ra ² are —CH ₂ (CF ₂ ) _r CF ₃ .
However, r is an integer of 0-3. The electrophotographic photoreceptor according to claim 1, wherein the A is one selected from the group consisting of compounds represented by the following formulas (2-1) to (2-6).

  The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a single layer structure containing the charge generating agent, the charge transporting agent, and the binder resin in the same layer.   4. The laminated structure according to claim 1, wherein the photosensitive layer has a laminated structure including a charge generation layer containing at least the charge generation agent and a charge transport layer containing the charge transfer agent and the binder resin. An electrophotographic photoreceptor according to any one of the above.   An electrophotographic photosensitive member according to any one of claims 1 to 5, wherein charging means, exposure means, developing means, and transfer means are arranged around the electrophotographic photosensitive member, and the electrophotographic photosensitive member is provided. An image forming apparatus characterized by not comprising a charge eliminating means for removing surface charge.   An electrophotographic photosensitive member according to any one of claims 1 to 5, wherein a charging unit, an exposing unit, a developing unit, and a transferring unit are arranged around the electrophotographic photosensitive member, and a hydrocarbon solvent is used. An image forming apparatus for wet development using a liquid developer in which toner is dispersed.

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