JP4523767B2 - Naphthalenecarboxylic acid derivative, electrophotographic photosensitive member and electrophotographic apparatus using the compound - Google Patents

Description

The present invention relates to a novel naphthalenecarboxylic acid derivative and an electrophotographic photosensitive member using the compound, more specifically, an electrophotographic photosensitive member used in an image forming apparatus such as an electrostatic copying machine, a facsimile machine, a laser beam printer, The present invention also relates to an electrophotographic apparatus provided with the photoreceptor.

In recent years, organic electrophotographic photoreceptors (OPC) have been widely put into practical use from the viewpoints of pollution-free, low cost, and various design of photoreceptor characteristics from the degree of freedom of material selection. The photosensitive layer of OPC is a laminate type photoreceptor in which a charge generation layer and a charge transport layer are laminated, a so-called function separation type photoreceptor, or a charge generation agent and a charge transport agent dispersed in a single photosensitive layer. A so-called single-layer type photoconductor has been proposed.
The charge transport agents used in these photoreceptors are required to have a high carrier mobility, but most of the charge transport agents with a high carrier mobility have a hole transport property, so that they are put to practical use. From the viewpoint of mechanical strength, the OPC that is used is limited to a negatively charged laminated photoconductor having a charge transport layer provided on the outermost layer. However, OPC in the negative charging process uses negative polarity corona discharge, so it is more unstable than that of positive polarity, and the amount of ozone generated is large, which can cause deterioration of the photoreceptor and adversely affect the use environment. Etc. is a problem.

  In order to solve such problems, OPC that can be used in a positive charging process is effective. For this purpose, it is necessary to use an electron transport agent as a charge transport agent. For example, in Patent Document 1, a compound having a diphenoquinone structure or a benzoquinone structure is used as an electron transport agent for an electrophotographic photoreceptor. Proposed. Patent Document 2 proposes the use of a benzenetetracarboxylic acid diimide compound as an electron transport agent for an electrophotographic photoreceptor.

However, conventional electron transporting agents such as a diphenoquinone derivative, a benzoquinone derivative, and a benzenetetracarboxylic acid diimide compound have problems such as precipitation because they have low compatibility with the binder resin. Further, since the amount that can be dispersed in the photosensitive layer is limited, the hopping distance becomes long, and the electron transfer hardly occurs in a low electric field. Therefore, it has been difficult to make a conventional photoreceptor containing an electron transport agent excellent in electron transport ability.
JP-A-1-206349 JP-A-5-142812

The object of the present invention is to solve the above technical problems and provide a novel compound suitable as an electron transporting agent in an organic electrophotographic photoreceptor and an electrophotographic photoreceptor having higher sensitivity than the conventional one using the compound. There is.

  As a result of intensive studies to solve the above problems, the present inventors have found that the naphthalenecarboxylic acid derivative represented by the general formula (1) has good dispersibility in the resin and is excellent in thin film formation and electron transport properties. As a result, it has been found that a high-sensitivity and high-performance element can be produced by using it as an electron transporting agent in an electrophotographic photosensitive member.

That is, the present invention

1. A naphthalenecarboxylic acid derivative represented by the general formula (1) (Chemical formula 1).

[In the formula, R is a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and a substituted or unsubstituted aryl group. A represents a substituted or unsubstituted alkylene group or cycloalkylene group. ]
2. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate, wherein the compound is contained in the photoreceptor layer.
3. An electrophotographic apparatus comprising the electrophotographic photosensitive member.
About.

  The novel naphthalenecarboxylic acid derivative obtained by the present invention has excellent electron transport properties, and when the compound is used in an electrophotographic photoreceptor, it has good dispersibility in a resin, and also has excellent electrical characteristics and repeated stability. An excellent and highly durable electrophotographic photoreceptor can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  First, R in the general formula (1) will be described. R is a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and a substituted or unsubstituted aryl group.

  Examples of the substituted or unsubstituted alkyl group include an alkyl group having 1 to 25 carbon atoms, preferably 1 to 10 carbon atoms, specifically a methyl group, an ethyl group, an n-propyl group, an n- Straight chain such as butyl group, n-pentyl group, n-hexyl group, n-peptyl group, n-octyl group, n-nonyl group, n-decyl group, i-propyl group, sec-butyl group, tert -Branched group such as butyl group, methylpropyl group, dimethylpropyl group, ethylpropyl group, diethylpropyl group, methylbutyl group, dimethylbutyl group, methylpentyl group, dimethylpentyl group, methylhexyl group, dimethylhexyl group, alkoxy Alkyl group, monoalkylaminoalkyl group, dialkylaminoalkyl group, halogen-substituted alkyl group, alkylcarbonylalkyl , Carboxyalkyl group, alkanoyloxyalkyl group, aminoalkyl group, esterified optionally substituted with a carboxyl group which alkyl group, and an alkyl group substituted with a cyano group. The substitution position of these substituents is not particularly limited, and as exemplified in the following formula group (2-1), some of the carbon atoms of the substituted or unsubstituted alkyl group are heteroatoms (N, O , S, etc.) are also included in the substituted alkyl group.

  More preferably, groups, such as a following formula group (2-2), are mentioned. In addition, the wavy line in a formula represents a connection part (hereinafter the same).

  Examples of the substituted or unsubstituted cycloalkyl group include a cycloalkyl ring having 3 to 25 carbon atoms, preferably 3 to 10 carbon atoms, specifically, a homocyclic ring from cyclopropane to cyclodecane, methylcyclo Those having an alkyl substituent such as pentane, dimethylcyclopentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, tetramethylcyclohexane, ethylcyclohexane, diethylcyclohexane, tert-butylcyclohexane, alkoxyalkyl groups, monoalkylaminoalkyl groups, dialkylamino Alkyl group, halogen-substituted alkyl group, alkoxycarbonylalkyl group, carboxyalkyl group, alkanoyloxyalkyl group, aminoalkyl group, halogen atom, amino group, Examples thereof include a cycloalkyl group substituted with a carboxyl group, a cyano group or the like which may be tellurized. The substitution position of these substituents is not particularly limited, and as exemplified in the following formula group (3-1), some of the carbon atoms of the substituted or unsubstituted cycloalkyl group are heteroatoms (N, A group substituted with O, S, etc.) is also included in the substituted alkyl group.

  More preferably, groups, such as a following formula group (3-2), are mentioned.

  Examples of the substituted or unsubstituted aralkyl group include groups in which an aromatic ring is substituted on the above-described substituted or unsubstituted alkyl group, and an aralkyl group having 6 to 14 carbon atoms is preferable. More specifically, benzyl group, perfluorophenylethyl group, 1-phenylethyl group, 2-phenylethyl group, terphenylethyl group, dimethylphenylethyl group, diethylphenylethyl group, tert-butylphenylethyl group, 3- Examples include phenylpropyl group, 4-phenylbutyl group, 5-phenylpentyl group, 6-phenylhexyl group, benzhydryl group, and trityl group. In consideration of charge transport properties, groups such as the following formula group (4) Further preferred.

  Examples of the substituted or unsubstituted aryl group include a phenyl group, a naphthyl group, a biphenyl group, a terphenyl group, a thienyl group, and a bithienyl group. In consideration of charge transport properties, groups such as the following formula group (5) Is more preferable.

  Next, A in the general formula (1) will be described. A is a substituted or unsubstituted alkylene group or cycloalkylene group.

  The substituted or unsubstituted alkylene group is a group selected from the following formula group (6).

  X1 to X10 each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkyloxy group, or a substituted or unsubstituted alkylthio group. , A substituted or unsubstituted aryl group.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. In view of charge transport properties, a fluorine atom and a chlorine atom are preferable.

  As a substituted or unsubstituted alkyl group, a C1-C10, for example, C1-C5 alkyl group is preferable, for example. Specifically, methyl, ethyl, n-propyl, n-butyl, n-propyl, straight chain, i-propyl, sec-butyl, tert-butyl, dimethylpropyl A branched group such as a group, ethylpropyl group or methylbutyl group is preferred.

  Examples of the substituted or unsubstituted cycloalkyl group include the same cycloalkyl rings having 1 to 25 carbon atoms, preferably 1 to 10 carbon atoms, as described above.

  As a substituted or unsubstituted alkyloxy group, a C1-C6 alkyloxy group is preferable. Specifically, a methoxy group, an ethoxy group, a propoxy group, an i-propoxy group, a butoxy group, a tert-butoxy group, a pentyloxy group, and a hexyloxy group are preferable.

As a substituted or unsubstituted alkylthio group, a C1-C6 alkylthio group is preferable. Specifically, methylthio group, ethylthio group, propylthio group, i-propylthio group, butylthio group, t-butylthio group, pentylthio group, and hexylthio group are preferable.
Examples of the substituted or unsubstituted aryl group include a phenyl group, a naphthyl group, a biphenyl group, a terphenyl group, a thienyl group, and a bithienyl group.

  The alkyl group, cycloalkyl group, alkyloxy group, alkylthio group, and aryl group corresponding to X1 to X10 may have a substituent, specifically, a hydroxyalkyl group, an alkoxyalkyl group, or a monoalkylaminoalkyl group. , Dialkylaminoalkyl group, halogen-substituted alkyl group, alkoxycarbonylalkyl group, carboxyalkyl group, alkanoyloxyalkyl group, aminoalkyl group, halogen atom, amino group, hydroxy group, optionally esterified carboxyl group, cyano group In addition to the above, an alkyl group which may have a substituent having 1 to 5 carbon atoms, an alkoxy group which may have a substituent having 1 to 6 carbon atoms, and the like are mentioned. The substitution position of these substituents is not particularly limited.

  More preferably, groups such as the following formula group (7) are exemplified.

  As the substituted or unsubstituted cycloalkylene group, a cycloalkylene having 4 to 15 carbon atoms, preferably 5 to 10 carbon atoms, specifically cyclopentanedimethylene, cyclopentanediethylene, cyclohexanedimethylene. , Cyclohexanediethylene, tetramethylcyclohexanedimethylene, and the like.

  The cycloalkyl ring contained in the cycloalkylene group may have a substituent, specifically, a hydroxyalkyl group, an alkoxyalkyl group, a monoalkylaminoalkyl group, a dialkylaminoalkyl group, a halogen-substituted alkyl group, an alkoxycarbonyl group. Alkyl group, carboxyalkyl group, alkanoyloxyalkyl group, aminoalkyl group, halogen atom, amino group, hydroxy group, carboxyl group which may be esterified, cyano group, etc., as well as the above 1 to 5 carbon atoms And an alkyl group which may have a substituent and an alkoxy group which may have a substituent having 1 to 6 carbon atoms. In addition, the substitution position of these substituents is not particularly limited.

  More preferably, groups such as the following formula group (8) are exemplified.

  Specific examples of the compound represented by the general formula (1) are given below, but the present invention is not limited to these compounds.

  The method for synthesizing the naphthalenecarboxylic acid derivative of the present invention is not particularly limited, but a known synthesis method (for example, JP-A-2001-265031 or J. Am. Chem. Soc., 120, 3231 (1998). For example, as shown in the following reaction formula (Schemes 1 and 2). That is, a method in which naphthalenecarboxylic acid or its anhydride is reacted with amines to react with monoimide and a diamine, or a method in which naphthalenecarboxylic acid or its anhydride is reacted with diamines to monoiminate and amines It can be obtained by a method of reacting

  Monoimidization is carried out without a solvent or in the presence of a solvent. Solvents such as benzene, toluene, xylene, chloronaphthalene, acetic acid, pyridine, picoline, dimethylformamide, dimethylacetamide, dimethylethyleneurea, dimethylsulfoxide, etc. Use what can be reacted in

  For pH adjustment, a buffer solution prepared by mixing a basic aqueous solution such as lithium hydroxide, sodium hydroxide or potassium hydroxide with an acid such as phosphoric acid is used.

  The dehydration reaction of the carboxylic acid derivative obtained by reacting the carboxylic acid derivative with amines is carried out without solvent or in the presence of a solvent. As the solvent, a solvent that does not react with raw materials or products, such as benzene, toluene, xylene, chloronaphthalene, bromonaphthalene, and acetic anhydride, can be reacted at a temperature of 50 to 250 ° C.

  Any reaction may be performed without a catalyst or in the presence of a catalyst, and is not particularly limited. For example, molecular sieves, benzenesulfonic acid, p-toluenesulfonic acid, and the like can be used as a dehydrating agent.

  Embodiments of the organic electrophotographic photoreceptor of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing an embodiment of the photoreceptor of the present invention. Reference numeral 1 denotes a conductive substrate, 2 denotes an undercoat layer, 3 denotes a photosensitive layer, 4 denotes a protective layer, and the undercoat layer 2 and the protective layer 4 are provided as necessary. The photosensitive layer 3 has a charge generation function and a charge transport function, and includes a single layer type in which both functions are provided in one layer, and a stacked type in which the charge generation layer and the charge transport layer are separated.

  The electrophotographic photosensitive member of the present invention can be applied to both a single layer type and a laminated type, but the effect by using the naphthalenecarboxylic acid derivative represented by the formula (1) of the present invention is remarkable in the single layer type photosensitive member. Appear in The single-layer type photoreceptor is provided with a single photosensitive layer containing at least a naphthalenecarboxylic acid derivative represented by the formula (1) which is an electron transfer agent, a charge generating agent, and a resin binder on a conductive substrate. It is a thing. Such a single-layer type photosensitive layer can handle both positive and negative charges with a single structure, but is preferably used with positive charge that does not require negative corona discharge. This single-layer type photoreceptor has advantages such as simple layer structure and excellent productivity, suppression of the occurrence of film defects in the photosensitive layer, and improvement in optical characteristics because there are few interfaces between layers. Have

  On the other hand, a multilayer photoreceptor is obtained by laminating a charge generation layer containing a charge generation agent and a charge transport layer containing a charge transfer agent in this order or in the reverse order on a conductive substrate. . However, since the charge generation layer is much thinner than the charge transport layer, it is preferable to form the charge generation layer on the conductive substrate and to form the charge transport layer thereon for protection. .

  Specifically, based on FIG. 1, the conductive substrate 1 serves as a support for each of the other layers simultaneously with the function as the electrode of the photoreceptor, and may be any of a cylindrical shape, a plate shape, and a film shape. Materials include simple metals such as iron, aluminum, copper, tin, platinum, stainless steel, and nickel, plastic materials with the above metals deposited or laminated, and conductive treatment, or aluminum iodide, tin oxide, indium oxide, etc. And glass coated with.

  The undercoat layer 2 can be provided as necessary, and is composed of a resin-based layer, an anodized oxide film, or the like, and prevents unnecessary charge injection from the conductive substrate to the photosensitive layer. It is provided as necessary for the purpose of defect coating, improvement in adhesion of the photosensitive layer, and the like. As the resin binder for the undercoat layer, polycarbonate resin, polyester resin, polyvinyl acetal resin, polyvinyl butyral resin, vinyl chloride resin, vinyl acetate resin, polyethylene, polypropylene, polystyrene, acrylic resin, polyurethane resin, epoxy resin, melamine resin, Silicone resins, polyamide resins, polystyrene resins, polyacetal resins, polyarylate resins, polysulfone resins, methacrylic ester polymers, copolymers thereof, and the like can be used in appropriate combinations. The resin binder includes silicon oxide (silica), titanium oxide, zinc oxide, calcium oxide, aluminum oxide (alumina), metal oxides such as zirconium oxide, metal sulfides such as barium sulfide and calcium sulfide, and silicon nitride. Further, it may contain metal nitride such as aluminum nitride, metal oxide fine particles and the like.

  Although the thickness of the undercoat layer depends on the composition of the undercoat layer, it can be arbitrarily set within a range where no adverse effect such as an increase in residual potential occurs when it is repeatedly used continuously.

  In the case of a single layer type, the photosensitive layer 3 is composed of one layer in which a charge generation layer and a charge transport layer are mixed. In the case of a laminated type (function separation type), the photosensitive layer 3 is mainly composed of two layers of a charge generation layer and a charge transport layer. Become.

  The charge generation layer is formed by vacuum-depositing an organic photoconductive substance or applying a material in which particles of an organic photoconductive substance are dispersed in a resin binder, and generates charge by receiving light. In addition, the injection efficiency of the generated charges into the charge transport layer is important at the same time as the charge generation efficiency is high, and it is desirable that the injection is good even in a low electric field with little electric field dependency. The charge generation layer can also be used with a charge generation agent as a main component and a charge transfer agent or the like added thereto.

  As the charge generating agent, phthalocyanine pigments, azo pigments, anthanthrone pigments, perylene pigments, perinone pigments, squarylium pigments, thiapyrylium pigments, quinacridone pigments and the like may be used, or these pigments may be used in combination. Especially as azo pigments, disazo pigments, trisazo pigments, as perylene pigments, N, N′-bis (3,5-dimethylphenyl) -3,4: 9,10-perylenebis (carboximide), as phthalocyanine pigments Is preferably metal-free phthalocyanine, copper phthalocyanine, titanyl phthalocyanine, and further X-type metal-free phthalocyanine, τ-type metal-free phthalocyanine, ε-type copper phthalocyanine, α-type titanyl phthalocyanine, β-type titanyl phthalocyanine, Y-type titanyl phthalocyanine, amorphous Titanyl phthalocyanine is preferred.

  Moreover, the charge generators exemplified above are used alone or in admixture of two or more so as to have an absorption wavelength in a desired region. Among the above-exemplified charge generating agents, in particular, a laser beam printer using a light source such as a semiconductor laser or an image forming apparatus of a digital optical system such as a facsimile requires a photoreceptor having sensitivity in a wavelength region of 700 nm or more. Therefore, for example, phthalocyanine pigments such as metal-free phthalocyanine and titanyl phthalocyanine are preferably 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, so that a perylene pigment or a bisazo pigment is preferable. Used for.

  As the resin binder for the charge generation layer, various resin binders conventionally used in the photosensitive layer can be used. For example, polyvinyl acetal resin, polyvinyl butyral resin, vinyl chloride resin, vinyl acetate resin, silicone resin, polycarbonate resin, polyester resin, polyethylene, polypropylene, polystyrene, acrylic resin, polyurethane resin, epoxy resin, melamine resin, polyamide resin, polystyrene resin Polyacetal resins, polyarylate resins, polysulfone resins, methacrylic acid ester polymers, copolymers thereof, and the like can be used in appropriate combinations.

  The charge transport layer is a coating film made of a material in which a charge transport agent is dispersed in a resin binder. The charge transport layer retains the charge of the photoconductor as an insulator layer in the dark, and the charge injected from the charge generation layer during light reception. Demonstrate the function to transport.

  Examples of the charge transport agent include a hydrazone compound, a pyrazoline compound, a pyrazolone compound, an oxadiazole compound, an oxazole compound, an arylamine compound, a benzidine compound, a stilbene compound, a styryl compound, polyvinyl carbazole, and a polysilane. Acid, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, pyromellitic acid, trimellitic acid, trimellitic anhydride, phthalimide, 4 -Electrons such as nitrophthalimide, tetracyanoethylene, tetracyanoquinodimethane, chloranil, bromanyl, o-nitrobenzoic acid, trinitrofluorenone, quinone, diphenoquinone, naphthoquinone, anthraquinone, stilbenequinone It can be used in combination with naphthalene carboxylic acid derivative represented by the formula (1) of the present invention Okuzai.

  Moreover, a hole transport agent can also be used as needed. As the hole transporting agent, for example, compounds having the structural formulas represented by (A-1) to (A-15) below may be used, but are not limited thereto.

  As the resin binder for the charge transport layer, various resin binders conventionally used in the photosensitive layer can be used. For example, polycarbonate resin, polyester resin, polyvinyl acetal resin, polyvinyl butyral resin, vinyl chloride resin, vinyl acetate resin, polyethylene, polypropylene, polystyrene, acrylic resin, polyurethane resin, epoxy resin, melamine resin, silicone resin, polyamide resin, polystyrene resin Polyacetal resins, polyarylate resins, polysulfone resins, methacrylic acid ester polymers, copolymers thereof, and the like can be used in appropriate combinations. In particular, polycarbonate resins and polyester resins having one or more of the structural units (B-1) to (B-3) shown below are suitable.

  In addition to the above components, these photosensitive layers may contain various known additives as long as the electrophotographic characteristics are not adversely affected. Specifically, antioxidants, radical scavengers, singlet quenchers, UV absorbers and other deterioration inhibitors, softeners, plasticizers, surface modifiers, dispersion stabilizers, waxes, acceptors, donors, etc. can do. In order to improve the sensitivity of the photosensitive layer, for example, known sensitizers such as terphenyl, halonaphthoquinones, acenaphthylene and the like may be used in combination with the charge generator.

The protective layer 4 is provided for the purpose of improving printing durability and can be provided as necessary, and is composed of a layer mainly composed of a resin binder or an inorganic thin film such as amorphous carbon. In the resin binder, silicon oxide (silica), titanium oxide, zinc oxide, calcium oxide, aluminum oxide (alumina), zirconium oxide are used for the purpose of improving conductivity, reducing friction coefficient, and imparting lubricity. Metal oxides such as barium sulfate and calcium sulfate, metal nitrides such as silicon nitride and aluminum nitride, metal oxide fine particles, or fluorine resin particles such as tetrafluoroethylene resin, fluorine comb type A graft polymerization resin or the like may be contained. In addition, for the purpose of imparting charge transportability, a charge transport material, an electron accepting material used in the photosensitive layer, or the novel naphthalenecarboxylic acid derivative of the present invention may be contained.

Next, a method for producing the electrophotographic photoreceptor of the present invention will be described. In the present invention, the single-layer type photoreceptor is prepared by appropriately dissolving or dissolving a naphthalenecarboxylic acid derivative (electron transport agent) represented by the general formula (1), a charge generator, a resin binder, and, if necessary, a hole transport agent. It is formed by dispersing and applying the obtained coating solution on a conductive substrate and drying.

  In the single layer type photoreceptor, the charge generating agent and the resin binder constituting the layer can be used in various ratios, and the charge generating agent is used in an amount of 0.1 to 50 parts per 100 parts by weight of the resin binder. What is necessary is just to mix | blend by the weight part, Preferably the ratio of 0.5-30 weight part. What is necessary is just to mix | blend an electron carrying agent in the ratio of 5-150 weight part with respect to 100 weight part of resin binders, Preferably it is 10-100 weight part. Moreover, what is necessary is just to mix | blend a hole transport agent in the ratio of 5-500 weight part with respect to 100 weight part of resin binders, Preferably it is 25-200 weight part. In addition, when using together an electron transport agent and a hole transport agent, the total amount of an electron transport agent and a hole transport agent is 20-500 weight part with respect to 100 weight part of resin binders, Preferably it is 30-200 weight. The part is appropriate.

  In order to maintain a practically effective surface potential, the thickness of the photosensitive layer in the single-layer type photoreceptor is preferably in the range of 5 to 80 μm, more preferably 10 to 50 μm.

  In the multilayer photoreceptor of the present invention, a charge generation layer containing a charge generation agent is first formed on a conductive substrate by means of vapor deposition or coating, and then the general formula (1) is formed on the charge generation layer. It is produced by applying a coating liquid containing a naphthalenecarboxylic acid derivative (electron transporting agent) represented by the formula (I) and a resin binder, and drying to form a charge transporting layer.

  In the laminated photoconductor, the charge generating agent and the resin binder constituting the charge generating layer can be used in various ratios, but the charge generating agent is 5 to 1000 parts by weight with respect to 100 parts by weight of the resin binder. It is preferable to add 30 to 500 parts by weight. In the case where a hole transport agent is contained in the charge generation layer, the ratio of the hole transport agent is 10 to 500 parts by weight, preferably 50 to 200 parts by weight with respect to 100 parts by weight of the binder resin. .

  The electron transporting agent and the resin binder constituting the charge transporting layer can be used in various proportions within a range that does not inhibit the transport of charges and a range that does not crystallize. It is appropriate to blend the electron transport agent in an amount of 10 to 500 parts by weight, preferably 25 to 200 resins with respect to 100 parts by weight of the resin binder so that it can be easily transported. When the charge transport layer contains another electron transport agent having a predetermined oxidation-reduction potential, the proportion of the other electron transport agent is 0.1 to 40 parts by weight, preferably 100 parts by weight of the binder resin. Is suitably 0.5 to 20 parts by weight.

  The thickness of the photosensitive layer in the multilayer photoreceptor is about 0.01 to 5 μm, preferably about 0.1 to 3 μm for the charge generation layer, and about 5 to 80 μm, preferably about 10 to 50 μm for the charge transport layer. . In a single layer type photoreceptor, between a conductive substrate and a photosensitive layer, and in a laminated type photoreceptor, between a conductive substrate and a charge generation layer, between a conductive substrate and a charge transport layer, or a charge. A barrier layer may be formed between the generation layer and the charge transport layer in a range that does not impair the characteristics of the photoreceptor. Further, a protective layer may be formed on the surface of the photoreceptor.

  When the photosensitive layer is formed by a coating method, the charge generator, charge transport agent, resin binder and the like exemplified above together with a suitable solvent, a known method such as a roll mill, ball mill, attritor, paint shaker or ultrasonic wave A dispersion liquid may be prepared by dispersing and mixing using a disperser or the like, and this may be applied and dried by a known means.

  As the solvent for preparing the dispersion, 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; benzene , Aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; acetone, Ketones such as methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide, etc. It is below. These solvents are used alone or in admixture of two or more.

  Hereinafter, the present invention will be specifically described by way of examples.

[Reference production example]
The monoanhydride monoimide, which is the starting material for the following examples, was prepared as described in J. Am. Am. Chem. Soc. , 120, 3231 (1998). Was adjusted by the method described in or by making slight changes to the process described therein. The structure of the product dimer described below was mainly confirmed by ¹ H-NMR magnetic resonance analysis and mass spectrometry in deuterated chloroform solvent. The ultraviolet absorption spectrum in a chloroform solvent was also measured. The imidoimine derivative of naphthalenecarboxylic acid exhibits absorption at about 300-380 nm, which is characteristic of the naphthalenecarboxylic acid imide chromophore in this solvent system.

(Synthesis of specific example (113))
First Step A reactor charged with 6.00 g (22.4 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 60 ml of DMF was heated to reflux. A mixture of 2.89 g (22.4 mmol) of 3-aminopentane and 30 ml of DMF was added dropwise thereto with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After cooling, the mixture was concentrated under reduced pressure. Toluene was added to the concentrated residue, insolubles were filtered off, and purified by silica gel column chromatography. The recovered product was recrystallized from toluene-hexane to obtain a monoimide body. Yield: 2.31 g
In mass spectrometry (FD-MS), since the peak of M / z = 337 was observed, it identified as the target object.
¹ H-NMR: (270 MHz, CDCl ₃ ) δ 0.91 (6H, t), 1.87-2.02 (2H, m), 2.14-2.31 (2H, m), 4.98 -5.09 (1H, m), 8.80 (4H, s).
IR: (ATR method) ν 3100, 3000-2800, 1784, 1743, 1710, 1666, 1242 cm ⁻¹ .
Second Step: Reaction in which 1.67 g (4.96 mmol) of a monoimide body, 0.253 g (2.48 mmol) of 1,3-diamino-2,2-dimethylpropane, 50 mg of p-toluenesulfonic acid, and 50 ml of toluene were charged. The vessel was dehydrated while being heated to reflux for 2 hr. After completion of the reaction, the mixture was filtered hot and the filtrate was concentrated.

The concentrated residue was purified by silica gel column chromatography and recrystallized from toluene-ethyl acetate. Yield: 1.96 g
The melting point was measured and found to be 208.4 ° C. In addition, in mass spectrometry (FD-MS), since the peak of M / z = 403 was observed, it identified as the target object.
¹ H-NMR: (270 MHz, CDCl ₃ ) δ 0.90 (6H, t), 1.10 (6H, s), 1.85-2.00 (2H, m), 2.15-2.36 (2H, m), 3.59 (2H, s), 3.81 (2H, s), 4.99-5.10 (1H, m), 8.61-8.75 (4H, m).

(Synthesis of specific example (115))
First Step A reactor charged with 6.00 g (22.4 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 60 ml of DMF was heated to reflux. To this, a mixture of 2.89 g (22.4 mmol) of 1,2-dimethylpropylamine and 30 ml of DMF was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After cooling, the mixture was concentrated under reduced pressure. Toluene was added to the concentrated residue, insolubles were filtered off, and purified by silica gel column chromatography. The recovered product was recrystallized from toluene-hexane to obtain a monoimide body. Yield: 2.20 g
The melting point was measured and found to be 214.4 ° C. In addition, in mass spectrometry (FD-MS), since the peak of M / z = 337 was observed, it identified as the target object.
¹ H-NMR: (270 MHz, CDCl ₃ ) δ 0.82 (3H, d), 1.10 (3H, d), 1.57 (3H, d), 2.61-2.74 (1H, m ), 4.81-4.93 (1H, m), 8.80 (4H, s).
Second Step: Reaction in which 1.67 g (4.96 mmol) of a monoimide body, 0.253 g (2.48 mmol) of 1,3-diamino-2,2-dimethylpropane, 50 mg of p-toluenesulfonic acid, and 50 ml of toluene were charged. The vessel was dehydrated while being heated to reflux for 2 hr. After completion of the reaction, the mixture was filtered hot and the filtrate was concentrated.

The concentrated residue was purified by silica gel column chromatography and recrystallized from toluene-ethyl acetate. Yield: 2.00g
In addition, in mass spectrometry (FD-MS), since the peak of M / z = 403 was observed, it identified as the target object.

(Synthesis of specific example (211))
First Step A reactor charged with 6.00 g (22.4 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 60 ml of DMF was heated to reflux. To this, a mixture of 2.89 g (22.4 mmol) of 1,5-dimethylhexylamine and 30 ml of DMF was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After cooling, the mixture was concentrated under reduced pressure. Toluene was added to the concentrated residue, insolubles were filtered off, and purified by silica gel column chromatography. The recovered product was recrystallized from toluene-hexane to obtain a monoimide body. Yield: 3.80 g
In addition, in mass spectrometry (FD-MS), since the peak of M / z = 379 was observed, it identified as the target object.
¹ H-NMR: (270 MHz, CDCl ₃ ) δ 0.80 (3H, d), 0.82 (3H, d), 1.15 to 1.53 (4H, m), 1.56 (3H, d ), 1.84-1.97 (1H, m), 2.08-2.20 (1H, m), 5.27 (1H, m), 8.80 (4H, s).
Second Step A reactor charged with 1.88 g (4.96 mmol) of monoimide, 0.253 g (2.48 mmol) of 1,3-diamino-2,2-dimethylpropane and 10 ml of acetic acid was heated to reflux for 5 hr. It was. This was concentrated, and the concentrated residue was purified by silica gel column chromatography and recrystallized from toluene-ethyl acetate. Yield: 1.60 g
In addition, in mass spectrometry (FD-MS), since the peak of M / z = 403 was observed, it identified as the target object.

The melting point was measured and found to be 207.8 ° C. In addition, in mass spectrometry (FD-MS), since the peak of M / z = 445 was observed, it identified as the target object.
¹ H-NMR: (270 MHz, CDCl ₃ ) δ 0.79 (3H, d), 0.82 (3H, d), 1.18 (6H, s), 1.20-1.57 (5H, m ), 1.59 (3H, d), 1.83-1.96 (1H, m), 2.09-2.23 (1H, m), 3.59 (2H, s), 3.81 ( 2H, s), 5.20-5.34 (1H, m), 8.61-8.80 (4H, m).

Evaluation of single-layer electrophotographic photoreceptor << Preparation of single-layer electrophotographic photoreceptor >>
Select α-type TiO2 phthalocyanine as the charge generating agent, Exemplified Compound (A-8) as the hole transporting agent, Exemplified Compound (113) as the electron transporting agent, blended together with the resin binder and solvent in the proportions shown below, The mixture was dispersed for 50 hours.

(Ingredients) (Parts by weight)
Charge generator 5
Hole transport agent 50
Electron transfer agent 30
Resin binder (polycarbonate) 100
Solvent (tetrahydrofuran) 800

  This dispersion was coated on the surface of a 30 mm diameter aluminum drum (conductive substrate) having a mirror-finished surface by a dip coating method and dried to produce a single layer type electrophotographic photosensitive member.

In order to verify the practicality of the obtained electrophotographic photosensitive member, it is mounted on a commercially available laser printer (HL-730 manufactured by Brother Industries, Ltd.) using a positively charged electrophotographic photosensitive member, and a normal temperature and humidity environment ( Under 20 ° C. and 50% RH), image quality and durability were evaluated by visual observation on the print samples after continuous printing of 5000 sheets in the A4 lateral direction.

Evaluation of Organic Electrophotographic Photoreceptor A photoconductor was prepared in the same manner as in Example 4 except that the electron transport material (Exemplary Compound (113)) used in Example 4 was replaced with a naphthalenecarboxylic acid derivative represented by Exemplified Compound (115). Produced.

Comparative Example 1 Evaluation of Organic Electrophotographic Photoreceptor The electron transport material (Exemplary Compound (113)) used in Example 4 was replaced with a diphenoquinone compound (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula. A photoconductor was prepared in the same manner as in Example 4.

[Examples 6 to 31]
A photoconductor was prepared in the same manner as in Example 4 except that the electron transport material (Exemplary Compound (113)) used in Example 4 was replaced with naphthalenecarboxylic acid derivatives represented by Exemplified Compounds (401) to (426). Even when evaluated, good results were obtained.

[Example 32]
Evaluation of laminated electrophotographic photoreceptor << Preparation of laminated electrophotographic photoreceptor >>
100 parts by weight of α-type TiO ₂ phthalocyanine as a charge generator, 100 parts by weight of polyvinyl butyral as a resin binder, and 2000 parts by weight of a solvent (tetrahydrofuran) were mixed and dispersed in a ball mill for 50 hours to prepare a coating solution for a charge generation layer. This coating solution was applied on the surface of a 30 mm diameter aluminum drum (conductive substrate) having a mirror-finished surface by a dip coating method and dried with hot air at 100 ° C. for 60 minutes to form a charge generation layer.

  Next, 100 parts by weight of the exemplary compound (113) as an electron transport material agent, 100 parts by weight of polycarbonate as a resin binder, and 800 parts by weight of a solvent (toluene) were mixed and dispersed in a ball mill for 50 hours to prepare a coating solution for a charge transport layer. . Then, this coating solution was applied onto the charge generation layer by a dip coating method and dried with hot air at 100 ° C. for 60 minutes to form a charge transport layer, thereby producing a multilayer electrophotographic photoreceptor.

Comparative Example 2 Evaluation of Organic Electrophotographic Photoreceptor The electron transfer agent (Exemplary Compound (113)) used in Example 32 was replaced with a compound represented by the following formula (4H-thiopyran-1,1-dioxide derivative). A photoreceptor was prepared in the same manner as Example 32 except for the above.

[Examples 33 to 50]

A photoconductor was prepared in the same manner as in Example 32 except that the electron transport material (Exemplary Compound (113)) used in Example 32 was replaced with naphthalenecarboxylic acid derivatives represented by Exemplified Compounds (601) to (618). Even when evaluated, good results were obtained.

The novel naphthalenecarboxylic acid derivative obtained by the present invention has excellent electron transport properties, and when the compound is used in an electrophotographic photoreceptor, it has good dispersibility in a resin, and also has excellent electrical characteristics and repeated stability. An excellent and highly durable electrophotographic photoreceptor can be obtained.

1 is a schematic cross-sectional view of an electrophotographic photoreceptor according to the present invention.

Explanation of symbols

1: Conductive substrate 2: Undercoat layer 3: Photosensitive layer 4: Protective layer

Claims (2)

A single-layer electrophotographic photosensitive member in which a photosensitive layer containing a naphthalenecarboxylic acid derivative represented by the following formula (1), a charge generator, and a resin binder is provided on a conductive substrate.

[In Formula (1) ,
R is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 25 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 25 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 14 carbon atoms , fluorine A group selected from the group consisting of an atom, a methoxy group, and an optionally substituted phenyl group, naphthyl group, biphenyl group, terphenyl group, thienyl group, and bithienyl group ,
A is selected from the group represented by the following formula:

An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1 .

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