JPH03284759A - Electrophotographic sensitive material - Google Patents

Abstract

PURPOSE:To prevent the delay in rising of the electrostatic charge potential by the repetitive use of the photosensitive body and to obviate the degradation in image density, unequal image densities, fogging or the ground staining at the time of reversal development by providing an intermediate layer consisting of a specific metal compd. CONSTITUTION:This photosensitive body is formed by providing the intermediate layer 13 on a conductive base body 11 and laminating, for example, a charge generating layer 17 and a charge transfer layer 19 thereon. The layer 13 is formed in incorporating >=1 kinds selected from tantalate (e.g.: lithium tantalate), titanate (e.g.: strontium titanate) and niobate (e.g.: barium niobate) therein. The layer 13 may be formed by a vacuum thin film forming method or wet process.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in electrophotographic photoreceptors.

[Conventional technology]

In recent years, organic photosensitive materials, which have advantages such as low cost, productivity, and non-pollution, have become popular as photoconductors used in electrophotographic copying machines.

Organic electrophotographic photoreceptors include photoconductive resins such as polyvinylcarbazole (PVK) and PVKTNF (
A charge transfer complex type photoreceptor represented by 2,4,7-)-linitrofluorenone), a pigment dispersion type represented by a phthalocyanine binder, and a functionally separated type photoreceptor using a combination of a charge generation substance and a charge transport substance. In particular, functionally separated photoreceptors are attracting attention.

When such a functionally separated high-sensitivity photoreceptor is applied to the Carlson process, it has low chargeability and poor charge retention characteristics (large dark decay), and these characteristics deteriorate significantly with repeated use, resulting in poor image quality. Moreover, it has disadvantages of density unevenness, fogging, and, in the case of reversal development, background smearing.

Furthermore, in general, high-sensitivity photoreceptors have reduced chargeability due to pre-exposure fatigue. This pre-exposure fatigue is mainly caused by light absorbed by charge-generating materials, so the longer the charges generated by light absorption remain in the photoconductor in a mobile state, the greater the number of charges. It is thought that the lower the chargeability becomes, the more the chargeability decreases due to pre-exposure fatigue. In other words, even if a charging operation is performed while the charge generated by light absorption remains, the surface charge will be neutralized by the movement of the remaining carriers, so the surface potential will increase until the residual charge is consumed. Therefore, the rise in surface potential is delayed by the amount of pre-exposure fatigue, and the apparent charging potential becomes lower.

For the above-mentioned drawbacks, for example, Japanese Patent Application Laid-Open No. 47-6341.
Nos. 48-3544 and 48-12034 have cellulose nitrate resin intermediate layers, as disclosed in JP-A No. 48-47344.52.
-25638.58-30757.58-63945.
58-95351.58-98739 and 60-66
No. 258 has a nylon resin intermediate layer, which was published in JP-A-49-6.
Nos. 9332 and 52-10138 disclose a maleic acid resin intermediate layer, and JP-A-58-105155 discloses a polyvinyl alcohol resin intermediate layer. In addition, intermediate layers have been proposed in which various conductive additives are contained in a resin in order to control the electrical resistance of the intermediate layer.

For example, JP-A No. 51-65942 uses an intermediate layer in which carbon or chalcogen-based substances are dispersed in a curable resin, and JP-A No. 52-82238 uses an isocyanate-based curing agent with the addition of a quaternary ammonium salt. JP-A-55-1180451 discloses a resin intermediate layer containing a resistance modifier, and JP-A-58-58556 discloses a resin intermediate layer in which aluminum or tin oxide is dispersed. ,
JP-A No. 58-93062 discloses a resin intermediate layer containing an organometallic compound;
Nos. 363 and 60-111255 have a resin intermediate layer in which conductive particles are dispersed, and JP-A-59-84257.
Nos. 59-93453 and 60-32054 include Tie
, and 5n02 powder are disclosed.

However, it is still insufficient in terms of the deterioration in chargeability due to repeated use, especially the delay in the rise of the 4th charge, and further improvements have been desired.

[Problem to be solved by the invention]

The present invention provides an electrophotographic photoreceptor that is highly sensitive, exhibits significantly less deterioration in chargeability due to pre-photofatigue, has no delay in the rise of charging potential even after repeated charging and exposure, and has small dark decay. The purpose is to provide.

[Means to solve the problem]

According to the present invention, in an electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are sequentially provided on a conductive support, the intermediate layer is made of at least one compound selected from tantalates, titanates, and niobate. An electrophotographic photoreceptor characterized by containing the following is provided.

An electrophotographic photoreceptor having a highly sensitive photosensitive layer has a strong tendency to cause a delay in the rise of the surface potential during charging and dark decay due to repeated use.

On the other hand, in general, when an intermediate layer is provided between a conductive substrate and a photosensitive layer, residual potential is likely to occur, especially when the intermediate layer is made of an insulating material such as a resin.

In view of the above, the present inventors solved the above problems by providing an intermediate layer made of the metal compound between the conductive substrate and the photosensitive layer in an electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive substrate. The inventors have discovered that the problem can be solved and have completed the present invention.

The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of the structure of the electrophotographic photoreceptor of the present invention, in which an intermediate layer 13 and then a photosensitive layer 15 are provided on a conductive substrate 11.

FIG. 2 is a sectional view showing another configuration example of the present invention.

The photosensitive layers are stacked in this order: a charge generation layer 17 and a charge transport layer 19.

FIG. 3 is a cross-sectional view showing yet another configuration example. The photosensitive layers are stacked in this order: a charge transport layer 19 and a charge generation layer 17.

FIG. 4, FIG. 5, and FIG. 6 are sectional views showing yet another example of the configuration. A protective layer 21 is provided on the structures shown in FIGS. 1, 2, and 3, respectively.

Next, the intermediate layer 13 will be explained.

As described above, the intermediate layer 13 is a layer containing at least one compound selected from tantalates, titanates, and nubates.

Examples of tantalates include lithium salts, sodium salts, potassium salts, rubidium salts, cesium salts, strontium salts, magnesium salts, and the like.

Examples of titanates include calcium salts, strontium salts, barium salts, cadmium salts, lead salts, magnesium salts, lithium salts, manganese salts, iron salts, cobalt salts, nickel salts, aluminum salts, potassium salts, etc. .

Examples of niobate compounds include barium salts, potassium salts, lithium salts, sodium salts, lead salts, strontium salts, rubidium salts, cesium salts, magnesium salts, and the like.

Such an intermediate layer is formed by a vacuum thin film forming method or a wet method.

Examples of the method for producing the vacuum film include resistance heating, vacuum evaporation using ion beam heating, sputtering, ion plate method, MBE, CVD, etc., and sputtering is preferably used.

Wet methods include dipping method, spray coating method,
spinner coating method, bead coating method, Meyer bar coating method, blade coating method,
Examples include roller coating method and curtain coating method.

In this case, as a coating liquid, a tantalate, a titanate, or a niobate may be dispersed in a solvent and used as it is, but a binder resin may also be used at the same time. As the binder resin, a resin having high solvent resistance to common organic solvents is preferable, considering the case where a photosensitive layer is coated thereon. Such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon, alkoxymethylated nylon, polyurethane, melamine resin, acrylic resin, alkyd resin, and epoxy resin. can be mentioned.

In addition, the thickness of the intermediate layer is 100 to 10 [preferably 50]
0 people - 5 pts.

The conductive support 11 has a volume resistance of 101oQ a1
1 or less, such as metals such as aluminum, nickel, chromium, nichrome, steel, silver, gold, and platinum, and metal oxides such as tin oxide and indium oxide, are deposited in film form or by sputtering. Coated cylindrical plastic, paper, etc., or plates of aluminum, aluminum alloy, nickel, stainless steel, etc., and their adhesives; 1. ．． 1.1. It is possible to use pipes that have been made into blank pipes by methods such as , extrusion, and drawing, and then surface-treated by cutting, superfinishing, polishing, and the like.

The photosensitive layer 15 in the present invention may be of a single layer type or a laminated type, but for convenience of explanation, the laminated type will be described here first.

The charge generation layer 17 is a layer mainly composed of a charge generation substance,
A binder resin may be used if necessary.

As the charge generating substance, inorganic materials and organic materials can be used. Examples of inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. In amorphous silicon,
Dangling bonds terminated with hydrogen atoms or halogen atoms, or doped with boron atoms, phosphorus atoms, etc., are preferably used.

On the other hand, organic materials include phthalocyanine pigments, naphthalocyanine pigments, perylene pigments, perinone pigments,
Quinacridone pigments, quinone condensed polycyclic compounds, squaric acid dyes, azulenium salt dyes, monoazo pigments, disazo pigments, trisazo pigments, and the like are used.

Among these charge generating substances, disazo or trisazo pigments represented by the following structural formula are particularly preferably used.

(However, Cp is a coupler residue, the same applies hereafter) (However, A
represents -zu-1-can, -8-. )I (However, R represents a hydrogen atom, a substituted or unsubstituted alkyl group.) (However, n represents an integer between 1 and 5.) (fniter L Rlt, hydrogen atom, alkyl group, Represents a halogen atom.) Cp-1χ0N=N-Cp Aminonaphthols having an acid group, compounds having an aliphatic or aromatic enolic ketone group (compounds having an active methylene group), etc. are used, and are preferably are represented by the following general formulas (1) to (11).

These coupler residues Cp include, for example, compounds having a phenolic hydroxyl group such as phenols and naphthols, aromatic amino compounds having an amino group, or amino groups and phenolic water [formula (1) above] ,(2),
In (3) and (4), X, Y, , Z, m and n each represent the following.

2 (R1 and R2 represent hydrogen or a substituted or unsubstituted alkyl group, R□ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group,
) Yl: hydrogen, halogen, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, carboxy group, sulfone group, substituted or unsubstituted sulfamoyl group, or -CO11hYz4 (R4 is hydrogen, an alkyl group or a substituted product thereof) , represents a phenyl group or a substituted product thereof, and Y2 is a hydrocarbon ring group or a substituted product thereof, a heterocyclic group or [in formulas (5) and (6),
R7 represents a substituted or unsubstituted hydrocarbon group, and A represents a divalent aromatic hydrocarbon or a divalent heterocyclic group containing a nitrogen atom in the ring (these rings may be substituted) .

X is the same as above. ] R5 is a hydrocarbon ring group or a substituted product thereof, a heterocyclic group or a substituted product thereof, a styryl group or a substituted product thereof, RG
represents hydrogen, an alkyl group, a phenyl group, or a substituent thereof, or R5 and RG may form a ring together with the carbon atoms bonded to them. ) is shown. ) Z: a hydrocarbon ring or its substituent, or a heterocycle or its substituent n: an integer of 1 or 2 m: an integer of 1 or 2] Ar1 [wherein, R is an alkyl group, a carbamoyl group, a carboxy group, or It represents an ester, Ar represents a hydrocarbon ring group or a substituted product thereof, and X is the same as above.

] [In the above formulas (8) and (9), R represents hydrogen or a substituted or unsubstituted hydrocarbon group, and Ar2 represents a hydrocarbon ring group or a substituted product thereof. ] Said general formula (1)
, (2), (3) or (4), examples include a benzene ring and a naphthalene ring, and examples of the heterocycle (which may have substitutions) include an indole ring,
Examples include a carbazole ring, benzolane ring, and dibenzofuran ring. Examples of the substituent in ring 2 include halogen atoms such as chlorine atom and bromine atom.

- Hydrocarbon ring groups in Y2 or Rs include phenyl group, naphthyl group, anthryl group, pyrenyl group, etc., and heterocyclic groups include pyridyl group, thienyl group, furyl group, indolyl group, benzofuranyl group, carbazolyl group. , dibenzofuranyl group, etc., and R
Examples of the ring formed by bonding 5 and Rt include a fluorene ring.

Substituents on the hydrocarbon ring group or heterocyclic group of Y2 or Rs or the ring formed by R5 and R6 include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, methoxy group, ethoxy group, propoxy groups, alkoxy groups such as butoxy groups, halogen atoms such as chlorine atoms and bromine atoms, dialkylamino groups such as dimethylamino groups and diethylamino groups, halomethyl groups such as trifluoromethyl groups, nitro groups, cyano groups, carboxyl groups, or their Examples include esters, hydroxyl groups, -5o, and sulfonic acid groups such as Na.

Examples of substituents for the phenyl group of R1 include halogen atoms such as chlorine atoms and bromine atoms.

Representative examples of the hydrocarbon group in R7 or R are:
Examples include alkyl groups such as methyl, ethyl, propyl and butyl groups, aryl groups such as phenyl, and substituted products thereof.

As a substituent in the hydrocarbon group of R7 or R9,
Examples include alkyl groups such as methyl, ethyl, propyl, and butyl groups; alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy; halogen atoms such as chlorine and bromine; hydroxyl and nitro groups. .

Typical examples of the hydrocarbon ring group in Ar or Ar are phenyl group, naphthyl group, etc.
Substituents for these groups include alkyl groups such as methyl, ethyl, propyl, and butyl, alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy, nitro, chlorine, bromine, etc. Examples include halogen atoms, dialkylamino groups such as cyano groups, dimethylamino groups, and diethylamino groups.

Furthermore, among X, a hydroxyl group is particularly suitable.

Among the above coupler residues, preferred is the general formula (
2) , (5) , (6) , (7) , (8
) and (9), and among these, those in which X in the general formula is a hydroxyl group are preferred. Also, among these, a coupler residue represented by the general formula (10): (Yl and 2 are the same as above) is preferred, and more preferably, the general formulas CztY2 and R2 are the same as above. ) is a coupler residue represented by

Furthermore, among the above-mentioned preferred coupler residues, general formula (12) or (13) '2' Examples of substituents include:

Binder resins used as necessary include polyamide, polyurethane, polyester, epoxy resin,
Examples include polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide, and the like.

Methods for forming the charge generation layer 17 include a vacuum thin film forming method and a casting method from a solution dispersion system.

For the former method, a vacuum evaporation method, a glow discharge decomposition method, an ion blating method, a sputtering method, a reactive sputtering method, a CVD method, etc. are used.

As the charge generation layer 17, the above-mentioned inorganic material or organic material layer can be formed satisfactorily.

In order to form a charge generation layer by the latter casting method, the above-mentioned inorganic or organic charge generation substance may be mixed with a binder resin if necessary using a ball mill, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, etc. It can be formed by dispersing with an attritor, sand mill, etc., diluting the dispersion liquid appropriately, and applying it. Application can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.

The thickness of the charge generation layer provided as described above is 0.
Approximately 0.01 to 54, preferably 0.05-2
− is.

The charge transport layer 19 can be formed by dissolving or dispersing a charge transport substance and a binder resin in a suitable solvent, applying the solution, and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added if necessary.

Charge transport materials include hole transport materials and electron transport materials.

Examples of the electron transport substance include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-dolinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone,
2,4,5.7-titranitroxanthone, 2,4°8
-trinidrothioxanthone, 2,6.8-trinitro-4H-indeno(1,2-b)thiophen-4-one, 1,3.7-dolinitrodibenzothiophenone-5,
Examples include electron-accepting substances such as 5-dioxide.

Examples of the hole-transporting substance include electron-donating substances represented by the following general formula, which are suitably used.

(In the formula, R1, R2, R3 and R4 represent a hydrogen atom, a substituted or unsubstituted aryl group, Ar□ represents a substituted or unsubstituted aryl group, and Ar□ and R are used together to form a ring. and n is an integer of O or 1.) R2, R, may be the same or different and represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a halogen atom. ) (In the formula, R represents an alkyl group having 1 to 11 carbon atoms, a substituted or unsubstituted phenyl group, or a heterocyclic residue; R,
, R, may be the same or different, and each represents a hydrogen atom, a lower alkyl group, a C0-04 hydroxyalkyl group, a 01-C4 chloroalkyl group, or a substituted or unsubstituted aralkyl group, and R2 and R1 may jointly form a nitrogen-containing heterocycle, and R4 and Rs may each be the same or different and represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a halogen atom. ) (However, R1 represents a lower alkyl group, a lower alkoxy group, or a halogen atom, and n is an integer of O to 4 (in the formula, R
1 represents a hydrogen atom or a halogen atom, and R2 represents a substituted or unsubstituted aromatic residue or a heterocyclic residue (however, the substituent is a halogen, cyano, di-lower alkylamino, substituted or unsubstituted dialkylamino group) , a lower alkyl group, a lower alkoxy group, and a nitro group) respectively substituted or unsubstituted phenyl group, styryl group,
It represents a naphthyl group or an anthryl group (wherein the substituent is selected from the group consisting of a di-lower alkylamino group, a lower alkyl group, a lower alkoxy group, a halogen atom, an aralkylamino group, or an amino group). ) B2 (In the formula, R,, R□ represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a di-lower alkylamino group, and R2 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a halogen atom, or a nitro group, and n represents 0 or 1.)13 (In the formula, R1, R2, R□ may be the same or different, and include a hydrogen atom, a lower alkyl group, a lower alkoxy group, a phenyl group, a phenoxy group, or represents a halogen atom.) (In the formula, R is a carbazolyl group, -pyridyl group, thienyl group, indolyl group, or furyl group, or (in the formula, R□
represents a hydrogen atom, a halogen atom, a cyano group, or a lower alkyl group, and Ar represents a hydrogen atom, a substituted or unsubstituted lower alkyl group, or a substituted or unsubstituted benzyl group. (R, R, represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, or a di-lower alkylamino group). ) (wherein, R1, R,, R3, R4, R represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a substituted or unsubstituted di-lower alkylamino group or a dibenzylamino group, and R5 represents a lower alkyl group or a benzyl group.) (In the formula, Ar represents a naphthalene ring, an anthracene ring, a styryl group, or a substituted product thereof, or a pyridine ring, a furan ring, or a thiophene ring, and R represents a lower alkyl group or a benzyl group.) )1 (wherein R1 represents a lower alkyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R2 represents a lower alkyl group, benzyl group, or phenyl group, and R1 represents a hydrogen atom or a halogen atom) , lower alkyl group, lower alkoxy group, di-lower alkylamino group, or nitro group.) R□ (In the formula, R1 represents a hydrogen atom, lower alkyl group, chloroethyl group, or hydroxyethyl group, and R2 represents a hydrogen atom or represents a halogen atom, R2 is a lower alkyl group, di-lower alkylamino group, diarylamino group, substituted or unsubstituted styryl group, substituted or unsubstituted aromatic ring residue (aromatic ring, benzene ring, naphthalene ring, anthracene ring) etc.), a substituted or unsubstituted heterocyclic residue (heterocycle represents a pyridine ring, a quinoxaline ring, a carbazole ring, etc.), an alkyl group, a chloro-lower alkyl group, an alkyl having 1 carbon number
-2 acyl group, an alkyl cycloalkyl group having 5 to 6 carbon atoms, or a substituted or unsubstituted aralkyl group. ) (In the formula, R represents a lower alkyl group, R2 represents a lower alkyl group, di-lower alkylamino group, diarylamino group, substituted or unsubstituted styryl group, substituted or unsubstituted aromatic ring residue (aromatic ring (benzene ring, naphthalene ring, anthracene ring, etc.), a substituted or unsubstituted heterocyclic residue (heterocycle is a pyridine ring, quinoxaline ring, carbazole ring, etc.) hydrogen atom, lower alkyl group, hydroxy lower a (in the formula, R
1, R3 and R4 are hydrogen atoms, amino groups, alkoxy groups, thioalkoxy groups, aryloxy groups, methylenedioxy groups, substituted or unsubstituted alkyl groups, halogen atoms, or substituted or unsubstituted aryl groups. R2 is hydrogen Represents an atom, an alkoxy group, a substituted or unsubstituted alkyl group, or a halogen. However, this excludes the case where R'', R2, R3 and R4 are all hydrogen atoms.In addition, Q
.

and n are integers of 1, 2, 3, or 4, each of which is 2,
When the integer is 3 or 4, the above R", R", R" and R4
may be the same or different.

A-CH, CH, -Ar1-CH, CH2-A (in the formula,
Ar1 represents a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group, and A represents a substituted or unsubstituted N-substituted rubazolyl group or 1-Ar2-N (However, Ar2 is a substituted or unsubstituted "'R = is an aromatic hydrocarbon group or a heterocyclic group, and R1 and R
2 is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. ). ) These charge transport substances may be used alone or in combination of two or more.

Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester,
Polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-
Examples include thermoplastic or thermosetting resins such as N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

As the solvent, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. are used.

The appropriate thickness of the charge transport layer 19 is about 5 to 100 tones. Further, in the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 17. As plasticizers, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as is.
The amount used is O~30% by weight based on the binder resin.
The degree is appropriate.

As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having perfluoroalkyl groups in the side chains are used, and the amount used is 0 to 1 weight by weight based on the binder resin. % is appropriate.

Next, a case where the photosensitive layer 15 has a single layer structure will be described.

The inorganic photosensitive layer can be made of the above-mentioned amorphous selenium, selenium alloy, amorphous silicon photosensitive layer, etc. by the vacuum evaporation method, glow discharge decomposition method, ion blating method, sputtering method, reactive sputtering method, etc.
It can be provided by a vacuum thin film forming method such as a VD method. Further, a photoreceptor in which two or more of these inorganic material layers are laminated also belongs to the scope of the present invention.

When a single-layer photosensitive layer is provided by a casting method, a functionally separated type consisting of a charge-generating substance and a charge-transporting substance is often used. That is, the above-mentioned materials can be used as the charge-generating substance and the charge-transporting substance.

A single-layer photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance and a binder resin in a suitable solvent, coating the solution and drying the solution. Furthermore, if necessary, a plasticizer, a leveling agent, etc. can be added.

As the binder resin, in addition to using the binder resin mentioned above for the charge transport layer 19 as is, the binder resin used for the charge generation layer 1
The binder resins listed in 7 may be used in combination.

The single-layer photosensitive layer is prepared by applying a coating liquid in which a charge generating substance, a charge transporting substance, and a binder resin are dispersed using a dispersing machine using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexanone, by dip coating, spray coating, or the like.
It can be formed by coating with bead coating, etc.

A photoreceptor in which a charge transporting substance is added to a eutectic complex formed from a pyrylium dye and a bisphenol A polycarbonate can also be formed by a similar coating method using an appropriate coating solution.

The thickness of the single photosensitive layer is 5 to 100. The degree is appropriate.

In the present invention, it is also possible to further provide a protective layer 21 on the photosensitive layer.

The protective layer 21 is provided for the purpose of protecting the surface of the photoreceptor, and materials used for this include ABS resin, AC5 resin, olefin rubinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, Polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone,
Examples of resins include polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin. It will be done. The protective layer also includes:
For the purpose of improving wear resistance, fluororesins such as polytetrafluoroethylene, silicone resins, and inorganic materials such as titanium oxide, tin oxide, potassium titanate, etc. dispersed in these resins can be added. A normal coating method is adopted as a method for forming the protective layer. Note that the thickness of the protective layer is suitably about 0.5 to 10 pm.

In the present invention, another intermediate layer (
(not shown) may also be provided.

Further, in the present invention, an antioxidant can be added in order to improve environmental resistance, particularly for the purpose of preventing a decrease in sensitivity and an increase in residual potential.

The antioxidant may be added to any layer containing an organic substance, but good results are obtained when it is added to a layer containing a charge transport substance.

The following are listed as antioxidants that can be used in the present invention.

Monophenolic 2,6-di-t-butyl-P-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stialyl-β-(3,5-di-t-
Butyl-4-hydroxyphenyl) propionate, etc.

Bisphenol compounds 2.2I-methylene-bis-(4-methyl-6-t-butylphenol), 2,2'-methylene-bis-(4-
ethyl-6-t-butylphenol), 4,4'-thiobis-(3-methyl-6-t-butylphenol), 4
, 4'-butylidenebis-(3-methyl-6-t-butylphenol) and the like.

Polymeric phenolic compound 1.1.3-tris-(2-methyl-4-hydroxy-
5-t-butylphenyl)butane, 1,3.5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[
Methylene-3-(3',5'-di-t-butyl-4'-
hydroxyphenyl)propionate comethane, bis[
3,3'-bis(4'-hydroxy-3'-t-butylphenyl)butyric acid coglycol ester,
such as tocopherols.

Paraphenylenediamines N-phenyl-N'-isopropyl-P-phenylenediamine, N,N'-di5ec-butyl-P-phenylenediamine, N-phenyl-N-sec-butyl-P-
phenylenediamine, N,N'-diisopropyl-P-
phenylenediamine, N,N'-dimethyl-N,N'-
di-t-butyl-P-phenylenediamine and the like.

Hydroquinones 2.5-di-t-octylhydroquinone, 2,6-sidodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-
Octyl-5-methylhydroquinone, 2-(2-octadecenyl)-5-methylhydroquinone, etc.

Organic sulfur compounds dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate, etc.

Organic phosphorus compounds triphenylphosphine, tri(nonylphenyl)phosphine, tri(dinonylphenyl)phosphine, tricresylphosphine, tri(2,4-dibutylphenoxy)phosphine, etc.

These compounds are known as antioxidants for rubber, plastics, oils and fats, and are easily available commercially.

In the present invention, the amount of the antioxidant added is 10 parts of the charge transport substance.
0.1 to 100 parts by weight, preferably
2 to 30 parts by weight of 6 (blank below) [Example] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by the following Examples. It should be noted that all parts used in the examples represent parts by weight.

Example 1 On a polyethylene terephthalate film on which aluminum was vapor-deposited, an intermediate layer, a charge generation layer coating liquid, and a charge transport layer coating liquid having the following compositions were sequentially laminated to form an intermediate layer of 0.3 Ijs and a coating liquid of 0.2 Ijs, respectively. A charge generation layer of part m and a charge transport layer of 22IJs were formed to prepare an electrophotographic photoreceptor of the present invention.

[Middle layer]

A film of lithium tantalate was formed by sputtering.

[Charge generation layer]

Charge generating substance having the following structural formula 5 parts cyclohexanone cyclohexane [Charge transport layer coating liquid] Charge transporting substance having the following structural formula 200 parts 150 parts 7 parts Methylene chloride 80 parts Example 2 On the same support as in Example 1, the following Intermediate layer coating liquid of composition,
A charge generation layer coating liquid and a charge transport layer coating liquid were sequentially applied and dried to form a 0.3 tone intermediate layer, a 0.2 tone charge generation layer, and a charge generation layer 20. A charge transport layer was formed to produce an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

Water methanol Sodium tantalate [Charge generation layer coating solution] Charge generation substance having the following structural formula: 150 parts 200 parts 50 parts 2 parts Cyclohexanone 2-butanone [Charge transport layer coating solution] Charge transporting substance having the following structural formula: 100 parts 70 parts parts 10 parts methylene chloride 100 parts Example 3 On a polyethylene terephthalate film provided with a Hastelloy conductive layer, an intermediate layer coating liquid, a charge generation layer coating liquid, and a charge transport layer coating liquid having the following compositions were sequentially applied and dried. and an intermediate layer of 2 mm, a charge generation layer of 0.3 II m, and a charge generating layer of 18 m, respectively.
A charge transport layer of - was formed to produce an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

Potassium tantalate 10 parts Toluylene-2,4-diisocyanate 0.2 parts 2-butanone 100 parts 4-methyl-2-pentanone 70 parts [Charge generation layer coating liquid] Charge generation substance having the following structural formula 3 parts Cyclohexanone tetrahydrofuran [ Charge Transport Layer Coating Solution] A charge transport layer was formed using 100 parts, 100 parts, and 9 parts of a charge transport material having the following structural formula to prepare an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

A film of rubinium tantalate was formed by sputtering.

[Charge generation layer] A film of arsenic selenium was formed by vacuum evaporation.

[Charge transport layer coating liquid]

Charge transport material having the following structural formula: 10 parts Tetrahydrofuran 81 parts Example 4 An intermediate layer, a charge generation layer, and a charge transport layer having the following compositions were sequentially laminated on an aluminum plate having a thickness of 0.14 mm.
Intermediate layer of 1-, charge generation layer of 1-, 75 parts of electro-tetrahydrofuran of 17- Example 5 On an electroformed nickel plate with a thickness of 0.1 m, an intermediate layer coating liquid of the following composition and a charge-'' transport chamber were applied. Coating liquid The charge generation layer coating liquid and the protective layer coating liquid were applied and dried one after another, each with a coating liquid of 0.34.
middle layer of 0.2. A charge generation layer of 18, a charge transport layer of 18 and a protective layer of 3 were formed to prepare an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

Water, methanol, cesium tantalate [Charge generation layer coating solution] β-type copper phthalocyanine polysulfone (Nissan Chemical: P-1700) Cyclohexanone [Charge transport layer coating solution] Charge transport material with the following structural formula: 100 parts 100 parts 4 parts 5 parts 1 part 500 parts 9 parts Tin oxide 80 parts Toluene 170 parts 2-butanone 100 parts Example 6 On the same support as in Example 4, an intermediate layer, a charge transport layer, and a charge generation layer having the following compositions were sequentially laminated. 5 middle class, 2
A four-tone charge transport layer and a 0.5R charge generation layer were formed to produce an electrophotographic photoreceptor of the present invention.

[Middle layer]

A film of strontium tantalate was formed by sputtering.

[Charge transport layer coating liquid]

Charge transport material having the following structural formula: 8 parts Methylene chloride [Protective layer coating solution] 80 parts Tetrahydrofuran 82 parts [Charge generating material] τ-type titanyl phthalocyanine was formed into a film by a vacuum evaporation method.

Example 7 On the same support as in Example 4, an intermediate layer coating solution having the following composition,
A charge transport layer coating solution, a charge generation layer coating solution and a protective layer coating solution were sequentially applied and dried to form an intermediate layer of IIZm, 20
A charge transport layer of -, a charge generation layer of 0.3 pm, and a protective layer of 5 IIm were formed to prepare an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

Magnesium tantalate 5 parts Methanol butanol [Charge transport layer coating liquid] 200 parts of charge transport substance with the following structural formula 100 parts 10 parts Methylene chloride 1,2-dichloroethane [Charge generation layer coating liquid] Charge generating substance with the following structural formula 70 parts 30 parts 2 parts U cyclohexanone 4-methyl-2-pentanone [protective layer coating liquid] 100 parts 0.2 parts Conductive titanium oxide Toluene 90 parts 220 parts n-butanol 60 parts Comparative Example 1 In Example 1 An electrophotographic photoreceptor of a comparative example was prepared in the same manner except that no intermediate layer was provided.

Comparative Example 2 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 2 except that sodium tantalate in the intermediate layer was not used.

Comparative Example 3 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 3 except that potassium tantalate was not used in the intermediate layer.

Comparative Example 4 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 4 except that the intermediate layer was not provided.

Comparative Example 5 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 5 except that cesium tantalate was not used in the intermediate layer.

Comparative Example 6 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 6 except that the intermediate layer was not provided.

Comparative Example 7 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 7 except that magnesium tantalate was not used in the intermediate layer.

The characteristics of each photoreceptor described above were evaluated as follows using an electrostatic copying tester (new model 5P-428 manufactured by Kawaguchi Electric).

First, apply -6,0KV (or) +6,0KV (7) discharge pressure and corona charging for 20 seconds, then dark decay and when the surface potential reaches 1800V or +800■, 5Qux tungsten light is applied. Irradiated.

At this time, the surface potential V1 (
V), ■2° (V) or when irradiated with light, the surface potential is -4
Exposure amount E4 required to reach 00V or +400■
゜.

(Qux-sec) was measured.

Further, this photoreceptor was irradiated with 10,000 fiux-sec of tungsten light having a color temperature of 2,856° to cause optical fatigue, and then V□, V21+, E4. , was measured.

The evaluation results are shown in Table-1.

Table 1 *Measurement not possible due to 800V charging Example 8 An intermediate layer, a charge generation layer coating liquid, and a charge transport layer coating liquid having the following compositions were sequentially laminated on a polyethylene terephthalate film on which aluminum was deposited. An intermediate layer of 0.3IIa, a charge generation layer of 0.2/a11, and a charge transport layer of 22741 were formed to prepare an electrophotographic photoreceptor of the present invention.

[Middle layer]

A film of strontium titanate was formed by sputtering.

[Charge generation layer]

2 parts of a charge generating substance having the following structural formula [Charge transport layer coating liquid] 7 parts of a charge transporting substance having the following structural formula 80 parts of methylene chloride Example 9 Coating an intermediate layer having the following composition on the same support as in Example 8. liquid,
A charge generation layer coating liquid and a charge transport layer coating liquid were sequentially applied and dried to form an intermediate layer of 0.3 parts, a charge generation layer of 0.2 parts m, and a charge transport layer of 20 μs, respectively. An electrophotographic photoreceptor of the invention was produced.

[Charge generation layer coating liquid]

5 parts of a charge generating substance having the following structural formula cyclohexanone 2-butanone [Charge transport layer coating liquid] 70 parts of a charge transporting substance having the following structural formula 30 parts 10 parts Forming a main layer and a charge transport layer of 18 ps, 1 part of an electron of the present invention A photographic photoreceptor was created.

[Intermediate layer coating liquid]

Lithium titanate 10 parts Polyester (Toyobo Byron 200) Toluylene-2,4-diisocyanate 2-butanone 4-methyl-2-pentanone [Charge generation layer coating liquid] Charge generation substance with the following structural formula 1 part 0.2 Parts 100 parts 70 parts 5 parts Methylene chloride 100 parts Example 10 On a polyethylene terephthalate film provided with a Hastelloy conductive layer, an intermediate layer coating liquid, a charge generation layer coating liquid, and a charge transport layer coating liquid having the following compositions were sequentially applied. , coated and dried to form 2 intermediate layers, 0.3 parts m of charge-generating cyclohexanone tetrahydrofuran [Charge transport layer coating solution] 150 parts of charge transport material having the following structural formula: 100 parts 9 parts Tetrahydrofuran 81 parts Example 11 An intermediate layer, a charge generation layer, and a charge transport layer having the following compositions were sequentially laminated on an aluminum plate with a thickness of 0.2 mm, and each layer had a thickness of 0.1 mm.
An electrophotographic photoreceptor of the present invention was prepared by forming an intermediate layer, an IPM charge generation layer, and a 17 charge transport layer.

[Middle layer]

A film of manganese titanate was formed by sputtering.

[Charge generation layer]

A film of arsenic selenium was formed by vacuum evaporation.

[Charge transport layer coating liquid]

Charge transport material having the following structural formula: 10 parts Tetrahydrofuran 75 parts Example 12 An intermediate layer coating liquid, a charge transport layer coating liquid, and a charge generation layer coating liquid having the following compositions were coated on an electroformed nickel plate having a thickness of 0.1 m. and a protective layer coating solution were sequentially applied and dried to form an intermediate layer with a threshold of 0.3, a charge generation layer with a threshold of 0.2, a charge transport layer with a thickness of 18 and a protective layer with a thickness of 3T, respectively. An electrophotographic photoreceptor was prepared.

[Intermediate layer coating liquid]

Water methanol Calcium titanate [Charge generation layer coating solution] β-type copper phthalocyanine 100 parts 100 parts 6 parts 2 parts Polysulfone (8san Kagaku: P-1700) Cyclohexanone [Charge transport layer coating solution] Charge transport of the following structural formula 4 parts of substance 400 parts 9 parts.

[Middle layer]

A film of barium titanate was formed by sputtering.

[Charge transport layer coating liquid]

Charge transport material with the following structural formula: 8 parts Methylene chloride [protective layer coating solution] 80 parts Tin oxide 80 parts Toluene 170 parts 2-butanone 100 parts Example 13 An intermediate layer having the following composition was formed on the same support as in Example 11. , a charge transport layer, and a charge generation layer were sequentially laminated to form an intermediate layer of 500 parts, a charge transport layer of 24 parts, and a charge generation layer of 0.5 parts m to produce an electrophotographic photoreceptor of the present invention. Tetrahydrofuran 82 parts [Charge generation layer] A metal-free phthalocyanine film was formed by vacuum evaporation.

Example 14 On the same support as in Example 11, an intermediate layer coating solution, a charge transport layer coating solution, a charge generation layer coating solution, and a protective layer coating solution having the following compositions were sequentially applied and dried. IIZa middle layer, 2
0- charge transport layer, 0.3 Ils charge generation layer, 5.
A protective layer having a thickness of cm was formed to prepare an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

Nickel titanate 5 parts Cyclohexanone 4-methyl-2-pentanone [Protective layer coating solution] 200 parts 100 parts Methanol butanol [Charge transport layer coating solution] Charge transport substance ioo of the following structural formula 100 parts 10 parts Chloride Methylene 1,2-dichloroethane [Charge generation layer coating liquid] Charge generation material having the following structural formula: 70 parts 30 parts 2 parts Conductive titanium oxide 90 parts Toluene 220 parts n-butanol 60 parts Comparative example 8 In Example 8, intermediate A comparative electrophotographic photoreceptor was prepared in the same manner except that no layer was provided.

Comparative Example 9 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 9 except that magnesium titanate in the intermediate layer was not used.

Comparative Example 10 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 10 except that lithium titanate was not used in the intermediate layer.

Comparative Example 11 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 11 except that the intermediate layer was not provided.

Comparative Example 12 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 12 except that calcium titanate was not used in the intermediate layer.

Comparative Example 13 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 13 except that the intermediate layer was not provided.

Comparative Example 14 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 14 except that nickel titanate was not used in the intermediate layer.

The characteristics of each photoreceptor described above were evaluated as follows using an electrostatic copying tester (new model 5P-428 manufactured by Kawaguchi Electric).

First, -5,8KV (or) +5.6KV (71 discharge voltage), corona charging is performed for 15 seconds, then dark decay is performed, and when the surface potential reaches 1800V or +800V, 4,5Qx tungsten light is applied. was irradiated.

At this time, the surface potential V at 1 second and 15 seconds after the start of charging, (
V), V, S (V) or the amount of exposure E necessary for the surface potential to become -400V or +400V during light irradiation
,. .

(Ωux-8ec) was measured.

Furthermore, after irradiating this photoreceptor with 8000 Qux-5ec of tungsten light with a color temperature of 2856° to cause optical fatigue,
Again in the same manner as above, V□, ■18E, . was measured.

The evaluation results are shown in Table-2.

Table 2 Example 15 An intermediate layer having the following composition, a charge generation layer coating solution, and a charge transport layer coating solution were sequentially laminated on a polyethylene terephthalate film on which aluminum was vapor-deposited to form an intermediate layer with a pitch of 0.3 each. , a 0.2-tone charge generation layer, and a 22-tone charge transport layer to prepare an electrophotographic photoreceptor of the present invention.

[Middle layer]

A film of barium niobate was formed by sputtering.

[Charge generation layer]

Charge generating substance with the following structural formula 5 copies 800
■No charge and cannot be measured Cyclohexanone cyclohexane [Charge transport layer coating liquid] 200 parts of a charge transport substance having the following structural formula.

100 parts 7 parts Methanol Potassium niobate [Charge generation layer coating solution] 200 parts of charge generating substance with the following structural formula 75 parts 2 parts Methylene chloride 80 parts Example 16 On the same support as in Example 15, an intermediate having the following composition was prepared. A layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution were sequentially applied and dried to a coating composition of 0.3. an intermediate layer of 0.2 μs, a charge generation layer of 20. A charge transport layer was formed to produce an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

150 parts of water Cyclohexanone 2-butanone [Charge transport layer coating liquid] 250 parts of charge transport substance having the following structural formula 100 parts 10 parts Polycarbonate (Lexan-141 manufactured by GE) 1
0 parts Methylene chloride 100 parts Example 17 On a polyethylene terephthalate film provided with a Hastelloy conductive layer, an intermediate layer coating liquid, a charge generation layer coating liquid, and a charge transport layer coating liquid having the following compositions were sequentially applied and dried. 2-m intermediate layer, 0.3 IIm charge generation layer and 18
A charge transport layer of - was formed to produce an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

Lithium niobate 1 part Toluylene-2,4-diisocyanate 0.2 parts 2-butanone 100 parts 4-methyl-2-pentanone 70 parts [Charge generation layer coating liquid] Charge generation substance having the following structural formula 4 parts Cyclohexanone 200 parts Tetrahydrofuran [Charge Transport Layer Coating Solution] 100 parts of charge transport substance having the following structural formula 9 parts Tetrahydrofuran 81 parts Example 18 An intermediate layer having the following composition, a charge generation layer, a charge transport layer were coated on an aluminum plate having a thickness of 0.2 cm. Layers are laminated sequentially, each with a thickness of 0.1-
an intermediate layer of 11 parts M, a charge generation layer of 17. A charge transport layer was formed to produce an electrophotographic photoreceptor of the present invention.

[Intermediate layer coating liquid]

A film of sodium niobate was formed by sputtering.

[Charge generation layer]

A film of arsenic selenium was formed by vacuum evaporation.

[Charge transport layer coating liquid]

10 parts of charge transport substance having the following structural formula 75 parts of tetrahydrofuran Example 19 On an electroformed nickel plate having a thickness of 0.1 m, an intermediate layer coating liquid, a charge transport layer coating liquid, and a charge generation layer coating liquid having the following compositions were applied. and a protective layer coating solution were sequentially applied and dried to 0.3% each. An electrophotographic photoreceptor of the present invention was prepared by forming an intermediate layer of 0.2 IJa, a charge generation layer of 0.2 IJa, a charge transport layer of 18 IJa, and a protective layer of 3 μs.

[Intermediate layer coating liquid]

Water methanol Lead niobate [Charge generation layer coating solution] 100 parts 100 parts 6 parts β-type copper phthalocyanine polysulfone (8 San Kagaku: P-1700) Cyclohexanone [Charge transport layer coating solution] Charge transport substance 3 with the following structural formula Part 1 part 100 parts 9 parts Methylene chloride [protective layer coating liquid] 80 parts Tin oxide 80 parts Toluene 170 parts 2-butanone 100 parts Example 2
0 On the same support as in Example 18, an intermediate layer, a charge transport layer, and a charge generation layer having the following compositions were sequentially laminated, each having 500 parts of the intermediate layer, 24 parts of the charge transport layer, and 0.5 parts of the charge transport layer. A charge generation layer was formed to prepare an electrophotographic photoreceptor of the present invention.

[Middle layer]

A film of strontium niobate was formed by sputtering.

[Charge transport layer coating liquid]

Charge transport substance with the following structural formula 8 parts Coating liquid,
A charge transport layer coating solution, a charge generation layer coating solution and a protective layer coating solution were sequentially applied and dried to form an intermediate layer of 1/Jl each, 20
An electrophotographic photoreceptor of the present invention was prepared by forming a charge transport layer of 0.3, a charge generation layer of 0.3, and a protective layer of 5.

[Intermediate layer coating liquid]

Magnesium niobate 3 parts Methanol 300 parts Butanol 100 parts [Charge transport layer coating liquid] Charge transport substance having the following structural formula 10 parts Tetrahydrofuran 82 parts [Charge generation delivery chamber] Copper phthalocyanine chloride was formed into a film by a vacuum evaporation method.

Example 21 On the same support as in Example 18, an intermediate layer having the following composition of methylene chloride 1,2-dichloroethane [charge generation layer coating liquid] 70 parts 30 parts charge generation substance having the following structural formula 3 parts cyclohexanone 4-methyl -2-Pentanone [Protective layer coating liquid] 130 parts 70 parts Conductive titanium oxide 90 parts Toluene 220 parts n-butanol 60 parts Comparative example 15 A comparative example was made in the same manner as in Example 15 except that no intermediate layer was provided. An electrophotographic photoreceptor was created.

Comparative Example 16 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 16 except that potassium niobate was not used in the intermediate layer.

Comparative Example 17 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 17 except that lithium niobate was not used in the intermediate layer.

Comparative Example 18 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 18 except that the intermediate layer was not provided.

Comparative Example 19 An electrophotographic photoreceptor of Comparative Example was prepared in the same manner as in Example 19 except that zinc niobate was not used in the intermediate layer.6 Comparative Example 20 All the procedures in Example 20 were repeated except that the intermediate layer was not provided. An electrophotographic photoreceptor as a comparative example was prepared in the same manner.

Comparative Example 21 An electrophotographic photoreceptor of a comparative example was prepared in the same manner as in Example 21 except that magnesium niobate was not used in the intermediate layer.

The characteristics of each photoreceptor described above were evaluated as follows using an electrostatic copying tester (new model 5P-428 manufactured by Kawaguchi Electric).

First, -5,5KV (or) +6. OKV was discharged and corona charged for 20 seconds, and then dark decayed and when the surface potential reached 1800 V or +800 V, tungsten light of 5 Qux was irradiated.

At this time, the surface potential V2 (
V), v2° (V) or when irradiated with light, the surface potential is -4
Exposure amount E4 required to reach 00V or +400■
゜.

(Qux-sec) was measured.

Further, this photoreceptor was irradiated with tungsten light having a color temperature of 2856 @ for 13000 Qux-sec to cause optical fatigue, and then the same procedure as above was carried out again to obtain 2, v2°, E. . was measured.

The evaluation results are shown in Table-3.

Table 3 *Measurement not possible due to no charging at 800V [Effects of the Invention] According to the present invention, it is possible to prevent deterioration of charging characteristics of a photoreceptor after repeated use.

That is, good images without background stains can be obtained during image density reduction, image density unevenness, fog, or reversal development in copying machines, printers, etc.

[Brief explanation of drawings]

1 to 6 are schematic cross-sectional views of an electrophotographic photoreceptor according to the present invention. Figure 3

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are sequentially provided on a conductive support, the intermediate layer contains at least one compound selected from tantalates, titanates, and niobate. An electrophotographic photoreceptor characterized by: