JPS63158561A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body high in sensitivity and superior in durability by using a photosensitive layer containing a specified disazo pigment. CONSTITUTION:The photosensitive layer formed on a conductive substrate contains the disazo pigment represented by formula I in which R1 is H, halogen atom, nitro, cyano, optionally substituted alkyl, such aryl, such aralkyl, such alkoxy, or such aryloxy group; each of A and A' is a coupler residue having a phenolic hydroxyl group; and each of Ar1 and Ar2 is an optionally substituted aromatic carbocyclic or heterocyclic group, thus permitting the obtained electrophotographic sensitive body to be improved in one or both of carrier generating efficiency and carrier transfer efficiency, and consequently, enhanced in sensitivity and especially in potential stability during successive repeated uses.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an electrophotographic photoreceptor using a novel photoconductive material.

[Conventional technology]

Conventionally, pigments and dyes exhibiting photoconductivity have been published in numerous publications.

For example, @RCA Revlew' Vol, 23
, P, 413-P, 419 (1962, 9)
The photoconductivity of phthalocyanine pigments has been published, and electrophotographic photoreceptors using these phthalocyanine pigments have been disclosed in US Pat. No. 3,397,086 and US Pat. No. 3,816,118. Other,
Examples of organic semiconductors used in electrophotographic photoreceptors include U.S. Pat. No. 4,315,983 and U.S. Pat. No. 43,271.
Publication No. 69 and Ra5each Disclosure
pyrylium dye shown in J20517 (1981, 5), methine squaric acid dye shown in US Patent No. 3824099, US Patent No. 3898
Examples include disazo pigments disclosed in Japanese Patent No. 084, US Pat. No. 4,251,613, and the like.

It is easier to synthesize than such organic semiconductors, and it can be synthesized as a compound that has photoconductivity for light at the required wavelength. Although the electrophotographic photoreceptor formed in a relatively large size has the advantage of improved color sensitivity, only a few of them can be put to practical use in terms of sensitivity and durability.

[Problems to be solved by the invention]

The present invention has been made to solve the conventional problems and provide an electrophotographic photoreceptor having high sensitivity and excellent durability.

[Means for solving problems]

The electrophotographic photoreceptor of the present invention is characterized by having a photosensitive layer containing a disazo pigment represented by the following general formula (1) on a conductive substrate.

〔Record〕

General formula (1) R1 in general formula (1) is a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group that may have a substituent, an aryl group, an aralkyl group, an alkoxy group, or an aryloxy group represents. Examples of halogen atoms include fluorine,
Examples include chlorine, iodine, and bromine atoms. The alkyl group is preferably a linear or branched alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-7' lobil group, an imo-globil group, an n-ethyl group, a 5ee-
Examples include butyl group, t@rt-ethyl group, and the like. Examples of the aryl group include phenyl group. Examples of the aralkyl group include p-)ruyl group, benzyl group,
Examples include phenethyl group and naphthylmethyl group. Examples of the alkoxy group include methoxy, ethoxy, and pro-4oxy groups.

Examples of the aryloxy group include phenoxy group. When R1 is an alkyl group, an aryl group, an aralkyl group, an alkoxy group, or an aryloxy group, examples of substituents include halogen atoms such as fluorine, chlorine, iodine, and bromine, methyl, ethyl, propyl, Alkyl groups such as isopropyl and butyl (except when R1 is an alkyl group), alkoxy groups such as methoxy, ethoxy, and propoxy, aryloxy groups such as phenoxy (excluding when R1 is an alkoxy group or an aryloxy group) ), nitro group, cyano group, trimethylamino, dibenzylamino, diphenylamino, morpholino,
Examples include amino groups that may have substituents such as piperidino and pyrrolidino.

A and A' in general formula (1) are each phenolic OH
represents a Kabra residue having a group, and A and A' may be the same or different. Preferred specific examples of the Kabra residues represented by A and A' are as follows: General formula (If) In general formula (II), X is fused to the benzene ring in the formula, Atoms necessary to form a polyaromatic product such as a 7talene ring, anthracene ring, or a heterocycle such as a carbazole ring, benzcarbazole ring, dibenzofuran ring, nopenzona 7talene ring, diphenylene sulfide 11, etc. Indicates a group.

The term formed by Xl in a condensed state with a benzene ring is more preferably a naphthalene ring, anthr7ane ring, a carbazole ring, or a benzcarbazole ring.

R2 and R3 each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, or form a cyclic amino group together with the nitrogen atom bonded to R2 and R3. represents the atomic group necessary for

Specific examples of alkyl groups include methyl group, ethyl group, globyl group, butyl group, etc. Specific examples of aralkyl groups include benzyl group, phenethyl group, naphthylmethyl group, etc. Specific examples of aryl groups include, for example. Examples of heterocyclic groups include phenyl group, zophenyl group, naphthyl group, anthryl group, etc., and examples of heterocyclic groups include carbazole, diynesyfurane, benzimidacilone, benzthiazole, thiazole, and pyrinone. Examples include groups that have been removed.

General formula (III) General formula (IV) General formula (1) R4 and R in (■) each represent a hydrogen atom, an alkyl group that may have a substituent, an aryl group, or an aralkyl group. Specific examples of alkyl groups, aryl groups, aralkyl groups, and substituents therefor include the above R
2, the same example as in the case of R5 can be given.

Substituents R2, R,, R4, R5 in formulas (ri) to (■)
17) The alkyl group, aryl group, aralkyl group, alkoxy group or heterocyclic group shown may further include other substituents, such as heron atoms such as fluorine, chlorine, iodine, bromine, methyl group, ethyl group, globyl group, Alkyl groups such as isoglobil group and methyl group (excluding cases where R2 etc. is an alkyl group),
Methoxy group, nidoxy group! Alkoxy groups such as lopoxy groups, aryloxy groups such as phenoxy groups (excluding cases where 82 etc. is an alkoxy group or aryloxy group), nitro groups, cyano groups, dimethylamine groups, dibenzylamino groups, diphenylamino groups, It may be substituted with an amino group which may have a substituent such as a morpholin group, a piperidino group, or a pyrrolidino group.

General formula (V), ・Yl・, H General formula (Vl) Y and Y2 are each a divalent group of an aromatic hydrocarbon or a divalent group of a heterocycle containing two nitrogen atoms in the ring in the formula. Indicates the atomic groups necessary to form a group.

Examples of divalent groups of aromatic hydrocarbons include divalent groups of monocyclic aromatic hydrocarbons such as o-7 dinilene, 0-naphthylene, perinaphthylene, 1,2-antrylene, and 9.10-7 enanthrylene. Examples include divalent groups of condensed polycyclic aromatic hydrocarbons such as y. Also, 2 of a heterocycle containing a nitrogen atom in the ring
As the valent group, 3.4-pyrazolediyl group, 2.3
-pyridinediyl group, 4,5-pyrimicindiyl group, 6
, 7-indazolediyl group, and 6,7-chiralindiyl group.

General formula Cvfi) "X2" R6 represents a diaryl group or a heterocyclic group which may have a substituent, specifically a phenyl group, a naphthyl group, etc.
It represents a heterocyclic group such as a lyl group, anthryl group, pyrenyl group, pyridyl group, chenyl group, furyl group, and carbazolyl group.

When the aryl group or heterocyclic group represented by R6 has a substituent, examples of the substituent include halodane atoms such as fluorine, chlorine, iodine, and bromine, and alkyl groups such as methyl group, ethyl group, globil group, isoglobil group, and methyl group. , an alkoxy group such as a methoxy group, an ethoxy group, an f-roxy group, a 7-aryloxy group such as a phenoxy group, a nitro group, a cyano group, a dimethylamino group, a dipenzolamino group, a diphenylamino group,
Examples include amino groups which may have substituents such as sulfolino group, piperidino group, and pyrrolidino group.

X2Fi has the same meaning as X2 in general formula (II).

General formula (1) R, , R, in the formula (Eki) represents an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group having a substituent. Specifically, a methyl group, an ethyl group, a globil group, etc. groups, alkyl groups such as methyl groups, pennol groups, 7enether groups, aralkyl groups such as naphthylmethyl groups, 7-aryl groups such as phenyl groups, naphthyl groups, anthryl, diphenyl groups, carbazole, dipenzofuran, benzimidasilone, benz A heterocyclic group obtained by removing one hydrogen atom from a heterocyclic ring such as thiazole, thiazole, and pyridine.

When the alkyl group, ar+7-al group, aralkyl group, or heterocyclic group represented by R, R, in formula (4) has a substituent, examples of the substituent include halo such as fluorine, chlorine, iodine, and bromine.
'y atom, methyl group, ethyl group, globyl group, isoglobyl group, alkyl group such as methyl group (excluding cases where R, etc. is an alkyl group), alkoxy group such as methoxy group, ethoxy group, f-lopoxy group, Examples include amino groups having four substituents such as a 7-aryloxy group such as a phenoxy group, a nitro group, a cyano group, a dimethylamino group, a dipenzolamino group, a diphenylamino group, a morpholino group, a piperidino group, and a pyrrolidino group. .

Ar and I Ar2 in the general formula (1) represent a carbocyclic aromatic ring group or a heterocyclic aromatic ring group which may have a substituent, specifically benzene, naphthalene/, anthracene, etc. Ar11 When the carbocyclic aromatic ring group or heterocyclic aromatic ring group represented by Ar2 has an It substituent, examples of this substituent include a norogon atom such as fluorine, chlorine, iodine, and bromine, a methyl group, an ethyl group, a 7'' Alkyl groups such as o-vir group, isoglobil group, butyl group, alkoxy groups such as methoxy group, ethoxy group, pro-4xy group, phenoxy group, aryl group such as phenoxy group, nitro group, cyano group, dimethylamine group , dipenzolamino group, diphenylamino group, morpholino group, piperidino group,
Examples include amine groups which may have substituents such as pyrrolidino groups.

A general method for producing the disazo pigment of general formula (1) used in the present invention will be described. General formula [! ] When A and A' are the same in the disazo pigment represented by the following general formula (N)
The diamine represented by is converted into a tetrazonium salt using a conventional method using sodium nitrite or nitrosyl sulfuric acid, and either aqueous coupling is performed with the coupler components A and A', or the resulting tetrazonium salt is converted into a stable salt such as a borofluoride salt. It can be obtained by extracting it as a salt and then coupling it in an organic solvent such as dimethylformamide.

If A and A' are different, in the coupling reaction, first couple with the first coupler component to form a monoazo pigment, and then couple with the second coupler component to form a disano pigment, or force fir-
It can be obtained by mixing the components and carrying out a coupling reaction, but in order to reliably obtain an asymmetric pigment with respect to A and A', the former two-step coupling method is preferred.

General formula (IX) R1 Next, specific examples of the disazo pigment of general formula (1) used in the present invention are shown below.

C.N.
eT) A coating containing the disazo pigment of the general formula (1) shown above exhibits photoconductivity and can therefore be used in the photosensitive layer of an electrophotographic photoreceptor.

That is, in the present invention, an electrophotographic photoreceptor is prepared by forming a film of the disano pigment of the general formula (1) on a conductive substrate by vacuum evaporation, or by forming a film by dispersing it in a suitable binder. Can be configured.

In a preferred embodiment of the present invention, the above-mentioned film exhibiting photoconductivity may be applied as a charge generation layer in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. can.

In order to obtain sufficient absorbance, the charge generation layer should be as thin as possible.
A thin film layer containing many of the above-mentioned photoconductive compounds and having a thickness of 5 μm or less, preferably 0,01 to 1 cotton, in order to shorten the range of the generated charge carriers. It is preferable that This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are transported by recombination or trapping without being deactivated. This is due to the need to inject into the layer.

The charge generation layer can be formed in the manner described above, for example, by dispersing the cis-azo pigment of general formula (1) in a suitable binder and coating it on the substrate. It can be obtained by forming Binders that can be used to form the charge generating layer by coating can be selected from a wide range of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthra7ane, and polyvinylpyrene. . Preferably, polyvinyl butyral, I realylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycargenate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide 0, polyvinylpyrinone, cellulose type Examples include insulating resins such as resin, urethane resin, epoxy resin, casein, polyvinyl 7K-A/, and polyvinylpyrrolidone. The resin contained in the charge generation layer is 80% by weight or less, preferably 40% by weight.
The following are suitable.

The solvent that dissolves these resins varies depending on the type of resin, and it is preferable to select a solvent that does not dissolve the underlying charge transport layer or subbing layer. Specific organic solvents include alcohols such as methanol, ethanol, isoprono and alcohol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfonate. Sulfoxides such as Nakasito, ethers such as dihydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform, methylene chloride,
Aliphatic halodanized hydrocarbons such as dichloroethylene, carbon tetrachloride, trichlorethylene, etc. or benzene,
Aromatic compounds such as toluene, xylene, ligroin, monochlorobenzene, and sochlorobenzene can be used.

Coating methods include dip coating method, spray coating method, spinner coating method, male coating method,
This can be carried out using a coating method such as a Mayer coating method, a blade coating method, a roller coating method, or a curtain coating method. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying at a temperature of 30°C to 200°C for 5 minutes to 2
It can be carried out stationary or under blown air for a period of time within a range of hours.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. have. In this case, the charge transport layer may be located on the side farther from the charge generation layer when viewed from the conductive substrate, or may be located between the conductive substrate and the charge generation layer.

When the charge transport layer is formed far from the charge generation layer,
The substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport material 5) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The term "electromagnetic waves" used herein includes a broad definition of "light rays" that includes gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers trap each other, resulting in a decrease in sensitivity.

Examples of charge transporting substances include electron transporting substances and hole transporting substances; examples of electron transporting substances include chloranil, bromoanil, tetracyanoethylene, tetracyanomethane, 2.4.7-) dinitro-9- Fluorenone, 2,4,5.7-tetranitro-9-fluorenone,
2.4.7-) Electron-withdrawing substances such as dinitro-9-zocyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinidrothioxanthone, and these electron-withdrawing substances There are polymerized ones.

Examples of hole-transporting substances include pyrene, N-ethyl force, /l
/ /4 Sole, N-isopropylcarpazole,
N-methyl-N-7enylhydrazino-3-methylten-9-ethylcarbazole, N,N-diphenylhydrazino-3-methyliso/-9-ethylcarbazole, N,
N-diphenylhydrano-3-methylidene-10-ethylphenothiazine, p-
Diethylaminobenzaldehyde-N, N-diphenylhydrazino, p-noethylaminobenzaldehyde N
-α-su7thi-N-phenylhydrazone, p-pyrrolidinobenzaldehyde-N,N-diphenylhydrazino, 1,3.3-1'limethylindoreni/-ω-aldehyde-N,N-diphenylhydrazino , p-diethylbenzaldehyde-3-methylpe/zthiazolinone-2-
Hydrazones such as hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1-phenyl-3-(p-diethylaminostyryl)
-5-(p-diethylaminophenyl)pyrazoline, 1
-[quinolyl(2)] -3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)) -3-(p-diethylaminostyryl)-5-(p- diethylaminophenyl)pyrazoli/,1-(6-medoxypyridyl(2)
) ) -3-(p-diethylaminostyryl)-5-
(p-diethylaminophenyl)pyrazoline, 1-[pyrinol(3))-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[revidyl(2))-3-(p- diethylaminostyryl)-5-(p-diethylaminophenyl)
Pyrazoline, 1-[pyrinol(2)]-]3-p-diethylaminostyryl-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-[pyrinol(2)
] -3-(α-methyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-(p-diethylaminostyryl)
-4-Methyl-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-(α-bear J Roux
p-diethylaminostyryl)-5-(p-noethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, 2-(p-diethylaminostyryl)-6
-Noethylaminope/, foimasashi-k, 2-(p--
) ethylaminophenyl)-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole and other oxazole compounds; 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole and other thiazole compounds; Compound, bis(4-diethylamino-2-
triarylmethane compounds such as (methylphenyl)-phenylmethane, 1,1-bis(4-N,N-diethylamino-2-methylphenylene)hegetane, 1.1,2.
I-aryl alkanes such as 2-tetrakis(4-N,N-dimethylamine-2-methylphenyl)ethane, triphenylamine, f! +)-N-vinylcarbazole, I-rivinylpyrene, polyvinylanthracene, ? Rivinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde stm, ethylcal i4
Examples include sol formaldehyde resin.

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium amorphous silicon, and cadmium sulfide can also be used.

Further, these charge transport substances can be used alone or in combination of two or more.

When the charge transport material does not have film-forming properties, a wave film can be formed by selecting an appropriate material. Examples of resins that can be used as binders include acrylic resins, polyarylates, I-lyesters, polycarnates,
Polystyrene, acrylonitrile-styrene copo')
r-17ri') Ronitrilutazoene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, ? Examples include insulating resins such as lyacrylamide, I-lyamide, and chlorinated rubber, and organic photoconductive polymers such as poly-IJ-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, it is 5 to 30 μm, but the preferred range is 8 to 20 μm.
I'm lazy. When forming a charge transport layer by coating,
Any suitable coating method, such as those described above, can be used.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive substrate having, for example, a conductive layer. Examples of substrates having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, and moly!
De/, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide 9-tin oxide alloy, etc. can be used to form a film by vacuum evaporation. plastics (e.g. polyethylene, polypropylene, polyvinyl vinyl, polyethylene terephthalate, acrylic resin, polyethylene fluoride, etc.),
Conductive particles (e.g. carbon black, silver particles, etc.)
A base material obtained by coating a glass material with a suitable binder on a glass material, a material material obtained by impregnating plastic or paper with conductive particles, a material material containing a conductive polymer, etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. Subbing layer, casein,
I-rivinyl alcohol, nitrocellulose, ethylene-
Acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), poly9-rethane, gelati/,
It can be formed from aluminum oxide, etc.

The thickness of the undercoat layer is 0.1 to 5NL, preferably 0.5 to 5NL.
3 μm is appropriate.

When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are arranged in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged. When exposed to light, chemotactic electrons are generated in the charge generation layer in the exposed area and injected into the charge transport layer, then reach the surface and neutralize the positive charges, causing a decrease in surface potential and creating an electrostatic contrast between the exposed area and the unexposed area. occurs. A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed.

Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones.

On the other hand, when the charge transport material consists of a hole transport material, it is necessary to charge the surface of the charge transport layer negatively. When exposed to light after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. After that, it reaches the surface and neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area.

During development, it is necessary to use a positively charged toner, contrary to the case where an electron transporting substance is used.

When using a photoreceptor in which the conductive layer, charge transport layer, and charge generation layer have JI When exposed to light after charging, electrons generated in the charge generation layer in the exposed area are injected into the charge transport layer and then reach the conductive substrate.

On the other hand, the holes generated in the charge generation layer cause the surface potential to attenuate, creating an electrostatic contrast with the unexposed area. A visible image can be obtained by developing the electrostatic latent image thus formed with a positively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones.

On the other hand, when the charge generation layer is made of a hole transporting substance, it is necessary to charge the surface of the charge generation layer positively υ, and when exposed to light after charging, the holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. and then reaches the conductive substrate. On the other hand, the electrons generated in the charge generation layer reach the surface and the electrostatic potential is attenuated, creating an electrostatic contrast with the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to the case where an electron transporting substance is used.

Further, in another specific example of the present invention, the above-mentioned hydrazones,
Direct photoconductive substances such as pyrazolines, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamines, and Vori-N-vinylcarbazoles, and inorganic photoconductive substances such as zinc oxide, cadmium sulfide, and selenium. The photosensitive coating may contain the disazo pigment of the general formula (1) described above as a sensitizer for a chemical substance.

This photosensitive film is formed by coating these photoconductive substances and the above-mentioned general formula (H) cis-sazo pigment together with a binder.

Another specific example of the present invention is an electrophotographic photoreceptor in which the above-mentioned disazo pigment of general formula (1) is contained in the same layer together with a charge transport substance.

At this time, in addition to the above-mentioned charge transport substance, a charge transfer complex compound consisting of polyJ-N-vinylcarbazole and trinitrofluorenone can be used.

The electrophotographic photoreceptor of this example can be prepared by dispersing the disazo pigment of general formula (I) and the charge transfer complex compound in a solution of polyester dissolved in tetrahydrofuran, and then forming a film thereon.

The pigment used in any of the photoreceptors contains at least one type of pigment selected from disazo pigments represented by the general formula (R), and its crystal form may be amorphous or crystalline. If necessary, two types of disazo pigments represented by the general formula (1) may be used in combination to increase the sensitivity of the photoreceptor or to obtain a panchromatic photoreceptor. It is also possible to use a combination of the above combinations or a charge generating substance selected from known dyes and pigments.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in a wide range of electrophotographic applications such as laser printers, CRT printers, LED printers, liquid crystal printers, and digital plate making. can.

〔Example〕

The present invention will be explained below with reference to Examples.

Examples 1 to 25 Ammonia aqueous solution of casein (casein 1
1.2ts, ammonia water 1? , 222 d of water) was applied using Mayer Parr so that the film thickness after drying was 1.0 μm, and then dried.

Next, the above-mentioned disazo pigment Al 5iP was added to 95% ethanol and tutilal resin (degree of tutilalization 63 mol%).
)2? was added to the dissolved solution and dispersed for 2 hours using a sand mill. This dispersion was applied onto the previously formed casein layer using a Mayer Par so that the film thickness after drying would be 0.5 μm, and dried to form a charge generation layer.

Next, the structural formula of hydrazone compound 5? and polymethyl methacrylate resin (number average molecular weight 100,000) 5/- were dissolved in 10 ml of benzene, and this was coated on the charge generation layer using a Mayer Par so that the film thickness after drying was 12 μm, and dried to form the charge transport layer. A photoreceptor of Example 1 was prepared by forming a photoconductor. Photoreceptors corresponding to Examples 2 to 25 were prepared in exactly the same manner using other exemplary pigments shown in Table 1 in place of disazo pigment AI.

The electrophotographic photoreceptor produced in this way was manufactured by Kawaguchi Electric Co., Ltd.
Using an electrostatic copying paper tester Model 5P-428, corona charging was carried out statically at -5 KV and 1
After holding the sample for a second, it was exposed to light at an illuminance of 21 ux to examine the charging characteristics. As for the charging characteristics, the surface potential (■) and the amount of exposure (Eμ) required to attenuate the potential to A when dark decayed for 1 second were measured. The results are shown in Table 1.

Table 1 Examples 26 to 30 Using the photoreceptors used in Examples 1, 2, 9, and 14, and 25, fluctuations in bright area potential and dark area potential during repeated use were measured.

The method is to attach the photoreceptor to the cylinder of an electrophotographic copying machine equipped with a -5.6kV corona charger, exposure optical system, developer, transfer charger, static elimination exposure optical system, and cleaner. The structure is such that an image is obtained on the transfer paper as the transfer unit is driven. Using this copier, the initial light potential (ML) and dark potential (VD) were set to around -100V and -600V, respectively, and the light potential (ML) and dark potential (Vo) were measured after 5000 uses. did. The results are shown in Table 2.

Example 31 On the charge generation layer prepared in Example 1, 2.4.7-dolinitro-9-fluoreno-15 and poly-4,4'-dioxydiphenyl-2,2'-glopancargenate (
Molecular weight 300,000)! M' is tetrahydrofuran 70! The coating amount after drying of the coating solution prepared by dissolving RIK is 10? /m'' and dried.

The electrostatic charge of the electrophotographic photoreceptor thus prepared was measured in the same manner as in Example 1. At this time, the charging polarity was set to ten. The results are shown below.

vo:■650? Example 32 A polyvinyl alcohol film having a thickness of 0.5 μm was formed on the aluminum surface of an aluminum-deposited polyethylene terephthalate film. Next, the dispersion of the cis-sazo pigment used in Example 2 was applied onto the polyvinyl alcohol cloud previously formed using a Mayer par so that the film thickness after drying would be 0.5μ, and dried to form a charge generation layer. 0 then structural formula of birazoline compound 5? and polyarylate resin (condensation polymer of bisphenol and terephthalic acid-isophthalic acid)
5? A solution obtained by dissolving the above in 70 TIL of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying was 10 islands, and dried to form a charge transport layer. The charging characteristics and durability characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 26, and the results are shown in Table 3.

vo: e580 gelt EH: 2.5 Lux・m*e According to the results in Table 3, the sensitivity is good and the potential stability during long-term use is also good.

Example 33 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 100 μm and dried to form a subbing layer with a thickness of 0.5 μm.

Then 2.4.7-) dinitro-9-fluorenone 5? and polyJ-N-vinylcart4 sol (number average molecular weight 30
0000) 5iP was dissolved in 70% tetrahydrofuran to form a charge transfer complex compound. This charge transfer complex compound and the above-mentioned disazo pigment A11? was added to a solution prepared by dissolving polyester resin (5iP, manufactured by Toyobo Co., Ltd.) in tetrahydrofuran 70+nj and dispersed therein. This dispersion was applied onto the undercoat layer and dried to prepare a 12μ photoreceptor.

The charging characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. The results are shown below. However, the charging polarity was set to ■.

vo: ■ 550v Ey2: 3.7 1ux-mee Example 34 The charge transport layer and charge generation layer of Example 1 were sequentially laminated on the casein layer of the aluminum base coated with the casein layer used in Example 33. A photoreceptor was formed in exactly the same manner as in Example 1, except that the difference was made, and the charging characteristics were measured in the same manner as in Example 1.

However, the charging polarity was O. The results are shown below.

vo: ■ 600 V Eye, : 4. [Effects of the Invention] According to the present invention, by using a specific disazo pigment in the photosensitive layer, either one or both of the carrier generation efficiency and the carrier transport efficiency inside the photosensitive layer can be improved. As a result, an electrophotographic photoreceptor with high sensitivity, durability, and excellent potential stability during long-term use is constructed.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising a photosensitive layer containing a disazo pigment represented by the following general formula [I] on a conductive substrate. [Note] General formula [I] ▲Mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 is a hydrogen atom, a halogen atom, a nitro group,
Represents a cyano group, an alkyl group that may have a substituent, an aryl group, an aralkyl group, an alkoxy group, or an aryloxy group. A and A' each represent a coupler residue having a phenolic OH group. Ar_1 and Ar_2 each represent a carbocyclic aromatic group or a heterocyclic aromatic group which may have a substituent. ) (2) A or/and A' in general formula [I] is the following general formula [II], general formula [III], general formula [IV], general formula [V]
, the electrophotographic photoreceptor according to claim 1, which is a coupler residue represented by general formula [VI], general formula [VII], or general formula [VIII]. [Note] General formula [II] ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ In the formula, X_1 represents the atomic group necessary to form a polycyclic aromatic ring or a heterocycle condensed with the benzene ring in the formula. show. R_2 and R_3 each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, or form a cyclic amino group with the nitrogen atom bonded to R_2 and R_3. represents the atomic group necessary to General formula [III] ▲ Numerical formulas, chemical formulas, tables, etc. are included▼ In the formula, R_4 represents an alkyl group, an aryl group, or an aralkyl group that may have a substituent. General formula [IV] ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ In the formula, R_5 represents an alkyl group, an aryl group, or an aralkyl group that may have a substituent. General formula [V] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, Y_1 is a divalent group of an aromatic hydrocarbon or a divalent group of a heterocyclic ring containing two nitrogen atoms in the formula. Indicates the atomic groups necessary to form. General formula [VI] ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ Y_2 in the formula represents a divalent group of aromatic hydrocarbon or a divalent group of heterocycle containing a nitrogen atom in the ring. General formula [VII] ▲There are numerical formulas, chemical formulas, tables, etc.▼ In the formula, R_6 represents an aryl group or a heterocyclic group that may have a substituent, and X_2 has the same meaning as X_2 in general formula [II]. have General formula [VIII] ▲ Numerical formulas, chemical formulas, tables, etc. are included▼ In the formula, R_7 and R_8 represent an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group that may have a substituent. X_3 represents the same meaning as X_1 in general formula [III].