JPS63141069A - electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing a novel azo pigment.

[Prior Art] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc sulfide as photosensitive components have been known.

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. , anthracene, pyrazolines, oxadiazoles, hydrazones, aryl alkanes, and other low-molecular organic photoconductors, phthalocyanine pigments, azo pigments, cyanine pigments,
Organic pigments and dyes such as polycyclic bovine non-pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid methine dyes are known.

In particular, photoconductive organic pigments and dyes are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has expanded, making it possible to use a large number of photoconductive compounds. Conductive organic pigments and dyes have been proposed. For example, US Pat. No. 4,123,270, US Pat. No. 4,247,614, US Pat. No. 4,251,613, US Pat.
Specification No. 21, Specification No. 4260672, Specification No. 42
An azo pigment that exhibits photoconductivity as a charge-generating substance in a photosensitive layer that is functionally separated into a charge-generating layer and a charge-transporting layer, as disclosed in Japanese Patent No. 68596, Japanese Patent No. 4278747, Japanese Patent No. 4293628, etc. Electrophotographic photoreceptors using the same are known.

Such azo pigments are generally produced by diazotizing a suitable amino compound and then coupling it with a coupler component. The coupler component includes β-oxynaphthoic acid derivatives such as naphthol AS, anthracene derivatives, Carbazole derivatives, dibenzofuran derivatives, benzocarbazole derivatives, and the like have been used in the field of electrophotographic photoreceptors.

An electrophotographic photoreceptor using such an organic photoconductor can be produced by coating by appropriately selecting a binder, so it is possible to provide an extremely highly productive and inexpensive photoreceptor.
In addition, it has the advantage that the sensitive wavelength range can be freely controlled by selecting the organic pigment, so it has been rapidly put into practical use in recent years.

However, this photoreceptor has problems in sensitivity and repeatability, so its use is limited, mostly in low-end electrophotographic copying machines.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel electrophotographic photoreceptor that has practical high sensitivity and stable potential characteristics in edge-reversing use.

[Means for Solving the Problems, Effects] The present invention provides a conductive support, in which R1 and R2 are the same or different and have a hydrogen atom, a halogen atom, a nitro group, or a cyano group as a substituent. represents an aryl group, a heterocyclic group which may have a substituent, or represents a hydrogen atom or a halogen atom)
An aromatic hydrocarbon ring or aromatic heterocycle to which the organic residue represented by may have a substituent that may be bonded via a bonding group.

The electrophotographic photoreceptor is characterized in that it has a photosensitive layer containing an azo pigment having a structure in which it is combined with an azo pigment.

To specifically explain the organic residue represented by the above general formula (I), in the formula, R1 and R2 are hydrogen atoms, phenyl having a halogen atom, nitro group or cyano group as a substituent,
Aryl groups such as diphenyl, naphthyl, anthryl,
Examples include heterocyclic groups such as pyridyl, chenyl, furyl, thiazolyl, carbazolyl, dibenzofuryl, benzimidazolyl, and benzothiazolyl, which may have a substituent.

Examples of substituents that the heterocyclic group has are 1. Examples include alkoxy groups such as methoxy and ethoxy; halogen atoms such as fluorine, chlorine, bromine and iodine; and halomethyl groups such as nitro, cyano and trifluoromethyl.

R and R2 may be the same or different, but especially R1
is a hydrogen atom, R2 is a fluorine atom, a chlorine atom, a bromine atom,
A phenyl group having an acceptor substituent such as a halogen atom such as an iodine atom, a nitro group, or a cyano group is preferred.

The reason for this is not yet clear, but by introducing a 7-ceptor substituent such as a halogen atom, nitro group, or cyano group into the pigment molecule at the same time as a carbonyl group, the π electron cloud within the pigment molecule can be charged with some charge. As a result of this bias, carrier generation efficiency and/or transportability are improved, resulting in higher sensitivity.At the same time, the oxidation potential of the pigment is increased, which reduces the ozone generated in the copying machine. It is presumed that the resistance to oxidizing substances such as NOx has increased, making it possible to maintain a stable potential even after repeated use.

Alternatively, it represents a hydrogen atom or a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom.

Examples of the aromatic hydrocarbon ring or aromatic heterocycle which may have a substituent which may be bonded via a bonding group to which the organic residue represented by general formula (I) is bonded include benzene, naphthalene, and fluorene. , hydrocarbon aromatic rings such as phenanthrene, anthracene, and pyrene, furan, thiophene, pyridine, indole, benzothiazole, carbazole,
Heteroaromatic rings such as acridone, dibenzothiophene, benzoxazole, benzotriazole, oxadiazole, thiazole, etc., and those in which the above aromatic rings are bonded directly or with an aromatic group or a non-aromatic group, such as triphenylamine, Diphenylamine, N-methyldiphenylamine, biphenyl, terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, benzophenone, stilbene, distyrylbenzene , tetraphenyl-p-phinidine diamine, tetraphenylbenzidine, and the like.

Examples of substituents that may be present on the aromatic hydrocarbon or aromatic heterocycle that may be present through the bonding group include alkyl groups such as methyl, ethyl, propyl, butyl, alkoxy groups such as methoxy and ethoxy, dimethylamino, diethylamino, etc. dialkylamino groups such as fluorine atoms, chlorine atoms, bromine atoms, etc., hydroxyl groups, nitro groups, cyano groups, halomethyl groups, and general formula -N-N-Cp
Examples include a substituted azo group represented by (m), and Cp in the above formula represents a coupler residue having a phenolic OH group, and examples include those having the structure described below in detail.

゛・Z″.

7Z+.

OHOH In the above formula, Zl is fused with a benzene ring to form an aromatic carbonized ring such as a naphthalene ring, anthracene ring, carbazole ring, benzocarbazole ring, dibenzofuran ring, benzonaphthofuran ring, or fluorenone ring, which may have a substituent. Indicates the organic residue necessary to form a hydrogen ring or an aromatic heterocycle.

Z2 is fused with a benzene ring to form a naphthalene ring, anthracene ring, carbazole ring, benzocarbazole ring, dibenzofuran ring, benzonaphthofuran ring, diphenylene sulfide ring, quinoline ring, isoquinoline ring, or acridine which may have a substituent. Indicates an organic residue necessary to form an aromatic hydrocarbon ring or an aromatic heterocycle such as a ring.

R4 and R5 are the same or different and are a hydrogen atom, an alkyl group that may have 3 substituents, an aralkyl group, an aryl group, a heterocyclic group, or a cyclic amine group containing in the ring the nitrogen atom to which R4 and R5 are bonded. shows.

R6 and R7 are the same or different and represent a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group, or a heterocyclic group.

R8 represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent.

Y represents a divalent hydrocarbon group or a heterocyclic group which may have a substituent.

Y2 represents a divalent aromatic hydrocarbon ring group which may have a substituent, and examples thereof include O-phenylene, 0-naphthylene, perinaphthylene, 1,2-antrylene, and 9,10-phenanthrylene groups.

Y3 represents a divalent aromatic hydrocarbon ring group which may have a substituent or a divalent heterocyclic group containing a nitrogen atom in the ring,
As the divalent aromatic hydrocarbon ring group, O-phenylene, 0
-Naphthylene, perinaphthylene, l,2-antrylene, 9,10-phenanthrylene groups, etc., and divalent heterocyclic groups containing a nitrogen atom in the ring include 3,4-pyrazolediyl, 2,3-pyridinediyl , 4.5-pyrimidinediyl, 6.7-indazolediyl, 5.6-
Examples include benzimidazolediyl and 6,7-chiralindiyl groups.

B represents an oxygen atom, a sulfur atom, or an N-substituted or unsubstituted imino group, and the substituent for N is an alkyl group, an aralkyl group, or an aryl group that may have a substituent.

Examples of the alkyl group in the above expression include methyl, ethyl, propyl, butyl, etc., aralkyl groups include benzyl, phenethyl, naphthylmethyl, etc., and aryl groups include phenyl, diphenyl, naphthyl, anthryl, etc. The heterocyclic groups include pyridyl, chenyl, furyl, thiazolyl, and carbazolyl.

Examples include groups such as dibenzofuryl, benzimidazolyl, and benzothiazolyl. Examples of cyclic amine groups containing a nitrogen atom in the ring include pyrrole, pyrroline, pyrrolidine, pyrrolidone, indole, indoline, isoindole, carbazole, benzindole, imidazole, pyrazole, and pyrazoline. , oxazine, phenoxazine, benzocarbazole, and the like.

Substituents include alkyl groups such as methyl, ethyl, and propyl, alkoxy groups such as methoxy and ethoxy, halogen atoms such as fluorine, chlorine, bromine, and iodine, fulkylamino groups such as dimethylamino and diethylamino, and phenylcarbamoyl. group, nitro group, cyano group, etc.

Representative examples of azo pigments used in the present invention are listed below.

The basic type is an azo pigment of the type represented by the general formula (■) or (rV).

They were classified by the number of n, and the organic residue moiety represented by the general formula (I) was expressed as A.

Note that the above basic type is a type where n=1.

They are classified and listed as n=2 type, n=3 type, and n=4 type.

n″11 A Exemplary pigment (1)-1 Pigment (1)-2 Exemplary pigment (1)-3 Exemplary pigment (1)-4 Exemplary pigment (1)-5 Exemplary pigment (t)-e Exemplary pigment (1)-7 Exemplary pigment (1)-8 r@ Exemplary pigment (1)-10 Exemplary pigment (1)-41 Exemplary pigment (1)-12 Exemplary pigment (+)-14 Exemplary pigment (1)-15 Exemplary pigment (1)-18 Exemplary pigment (1)-17 Exemplary pigment (1)-t.

Exemplary pigment (1)-1! ] Exemplary pigment (1)-20 Exemplary pigment (1)-21 n=2 1
A Exemplary Pigment (2)-1 Exemplary Pigment (2)-2 Exemplary Pigment (2)-3 Exemplary Pigment (2)-4 Exemplary Pigment (2)-5 Exemplary Pigment (2)-8 Exemplary Pigment (2)-7 Exemplary pigment (2)-8 Exemplary pigment (2)-9 Exemplary pigment (2)-10 Exemplary pigment (2)-11 A -N -N -@-c )I -CH-@-CH-
CH-@)-N-N-A Exemplary Pigment (2)-15 Exemplary Pigment (2)-16 Exemplary Pigment (2)-1? Exemplary Pigment (2)-18 Exemplary Pigment (2)-18 Exemplary Pigment (2)-20 Exemplary Pigment (2)-23 Exemplary Pigment (2)-25 Exemplary Pigment (2)-27 Exemplary Pigment (2)-28 Exemplary Pigment Pigment (2)-2! ] N Exemplary pigment (2)-30 Exemplary pigment (2)-31 Exemplary pigment (2)-32 Exemplary pigment (2)-33 Exemplary pigment (2)-35 Exemplary pigment (2)-38 Exemplary pigment (2)- 37 " Exemplified Pigment (2)-39 Exemplified Pigment (2)-40 Exemplified Pigment (2)-41 Exemplified Pigment (2)-44 Exemplified Pigment (2)-45 Exemplified Pigment (2)-49 Exemplified Pigment (2)- 50 Exemplified Pigment (2)-52 Exemplified Pigment (2)-53 Exemplified Pigment (2)-55 Exemplified Pigment (2)-58 Exemplified Pigment (2)-57 Exemplified Pigment (2)-58 Exemplified Pigment (2)-80 Exemplary Pigment (2)-61 Exemplary Pigment (2)-82 Exemplary Pigment (2)-[14 Exemplary Pigment (2)-85 Exemplary Pigment (2)-88 Exemplary Pigment (2)-87 Exemplary Pigment (2)-88 Exemplary pigment (2)-70 Exemplary pigment (2)-71 Exemplary pigment (2)-72 Exemplary pigment (2)-73 Exemplary pigment (2)-74 Exemplary pigment (2)-75 Exemplary pigment (2)-77 Exemplary pigment Pigment (2)-78 Exemplary pigment (2)-80 Exemplary pigment (2)-81 Exemplary pigment (2)-82 Exemplary pigment (2)-83 Exemplary pigment (2)-84 Exemplary pigment (2)-85 Exemplary pigment (2)-88 Exemplary Pigment (2)-87 Exemplary Pigment (2)-88 Exemplary Pigment (2)-89 Exemplary Pigment (2)-90 Exemplary Pigment (2)-92 Exemplary Pigment (2)-93 Exemplary Pigment ( 2)-94 Exemplified Pigment (2)-95 Exemplified Pigment (2)-98 Exemplified Pigment (2)-97 Exemplified Pigment (2)-99 Exemplified Pigment (2)-100 Exemplified Pigment (2)-101 Exemplified Pigment (2) )-102 Exemplary pigment (2)-103 Exemplary pigment (2)-104 Exemplary pigment (2)-105 Exemplary pigment (2)-108 Exemplary pigment (2)-107 Exemplary pigment (2)-108 Listed below An example of a disazo pigment having an organic residue selected from the organic residues represented by the general formula (I) and an organic residue corresponding to the general formula (m) that is different from the selected organic residue. It is.

Exemplary pigment (2)-110 Exemplary pigment (2)-111 Exemplary pigment (2)-112 Exemplary pigment (2)-113 Exemplary pigment (2)-114 Exemplary pigment (2)-118 Exemplary pigment (2)-117 Exemplary pigment Pigment (2)-119 Exemplary pigment (3)-1 Exemplary pigment (3)-2 Exemplary pigment (3)-3 Exemplary pigment (3)-4 Exemplary pigment (3)-5 Exemplary pigment (3)-13 Exemplary pigment (3)-8 Exemplary Pigment (3)-9 Exemplary Pigment (0-1 Exemplary Pigment (0-2) Exemplary Pigment (0-3 Exemplary Pigment (4)-4) The azo pigment used in the present invention is first Journal of the Department of Organic Synthetic Chemistry, Volume 16, No. 1 (1958)
After obtaining 3-oxyfluorenone-2-carboxylic acid by the method described on page 34, it was synthesized by condensation with the corresponding amino compound by the method described in Yutaka Hosoda, Dye Kagaku, page 644. Use the coupler obtained by washing.

The corresponding amine compound was diazotized by a conventional method.

After carrying out an aqueous coupling reaction in the presence of an alkali, or once isolating the diazonium salt of the amino compound in the form of a salt such as a borofluoride salt or a zinc chloride double salt, a suitable solvent such as N,N-dimethylformamide, N, N
- It can be produced by an organic solvent coupling reaction in an organic solvent such as dimethylacetamide or dimethyl sulfoxide in the presence of a base such as sodium acetate, pyridine, trimethylamine, or triethylamine.

Further, the azo pigment used in the present invention (in the case of the type where n=2, 3.4) only needs to contain one or more organic residues represented by the general formula (1) in the same molecule.

General formula CCH3CNH+-A r-fNH2)J
(X ■).

(In the formula, Ar is the same as above, 1m is an integer of 1, 2 or 3, and !L is an integer of 3.2 or 1) is diazotized by a conventional method, and the resulting diazonium salt is After coupling with the coupler component in the presence of Flukali, 1 is hydrolyzed with a mineral acid such as hydrochloric acid to obtain a reaction product whose structural formula corresponds to 1. After diazotization of this product again by a conventional method, another phenolic It may be produced by sequential coupling reaction with a coupler component having an OH group, or by adding a diazonium salt obtained by a conventional method to a mixed coupler solution containing at least one coupler component,
It may be produced by a coupling reaction in the presence of an alkali.

Typical synthesis examples are shown below.

Synthesis Example 1 (Exemplary Pigment (2)-1) 80 m of water in a 500 m beaker, 25.3 mJ of concentrated hydrochloric acid
Add L (0.29 mol), cool in an ice water bath, and then add O.
- 7.1 g (0,029 mol) of dianisidine was added, and the liquid temperature was brought to 3°C while stirring.

Next, add 4.2 g (0,061 mol) of sodium nitrite to 7 m of water.
1 was added dropwise over 10 minutes while controlling the temperature of the solution to below 5°C. After the dropwise addition was completed, the solution was stirred for another 30 minutes at the same temperature. Carbon was added to the 0 reaction solution and filtered to obtain a tetrazotized solution. .

Next, put 700 ml of dimethylformamide into a two-liter beaker, add 53.0 g (0.53 mol) of triethylamine, and add 3-hydroxyfluorenone-2-carboxylic acid.
20.3 g (0,061 mol) of 0-fluoroanilide was added and dissolved.

Cool this coupler solution to 5℃ and adjust the liquid temperature to 5-10℃.
The above-mentioned tetrazotization solution was added dropwise with stirring over 10 minutes while controlling the temperature, then stirred for 2 hours, and then left overnight at room temperature. After filtering, washing and filtering with water, A water paste of 24.7 g of crude pigment was obtained.

Next, stirring and filtration was repeated four times at room temperature using 400 ml of N,N-dimethylformamide.

Then, 2 in each case with 400 ml of methyl ethyl ketone.
After filtration with stirring was repeated, the mixture was dried under reduced pressure at room temperature to obtain 23.8 g of purified pigment.

Yield 88.0%, melting point 〉250℃ Elemental analysis Calculated value (%) Experimental value (%) C69,76
9,4 H3,473,46 N 9.03 9.09 Synthesis Example 2 (Mixture of Exemplary Pigment (2)-1, (2)-119, (2)-120) Pour 700 m of dimethylformamide into a 2-m beaker. Add 53.0 g (0.53 mol) of triethylamine,
15 g (0,031 mol) of 2-hydroxyfluorenone-2-carboxylic acid-〇-fluoroanilide and 3-
10.84 g (0,031 mol) of hydroxyfluorenone-2-carboxylic acid-〇-chloroanilide was added and dissolved.

This mixed coupler solution was cooled to 5℃, and the liquid temperature was 5 to 1
While controlling the temperature at 0°C, the tetrazotized solution obtained in the same manner as in Synthesis Example 1 was added dropwise with stirring over 30 minutes.
The reaction mixture was stirred for several hours and left overnight at room temperature, then filtered, washed with water, and filtered to obtain a water paste containing 25.6 g of crude pigment in terms of solid content. Thereafter, in the same manner as in Synthesis Example 1, 23.2 g of purified pigment was obtained. Melting point >250° C. The coatings containing the azo pigments described above exhibit photoconductivity and can therefore be used in photosensitive layers of subsequent electrophotographic photoreceptors.

That is, in a specific example of the present invention, an electrophotographic photoreceptor can be prepared by forming a film on a conductive support by dispersing the azo pigment described above in a suitable binder.

In a preferred embodiment of the present invention, the photoconductive coating described above can 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.

The charge generating layer contains as much of the aforementioned photoconductive azo pigment as possible in order to obtain sufficient absorbance, and
In order to efficiently transport the generated charge carriers to the interface with the charge transport layer or the interface with the conductive substrate, a thin film layer, for example, a thin film layer having a thickness of 5 IL or less, preferably 0.01 to 1 L, is used. It is desirable to do so.

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 must be injected into the charge transport layer without being deactivated by recombination or trapping. This is due to the fact that

The charge generating layer can be formed by dispersing the azo pigment described above in a suitable binder and applying it onto the substrate using a trowel. The binder that can be used to form the charge generating layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably polyvinyl butyral, polyvinyl benzal, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose type. resin, urethane resin, casein,
Examples include insulating resins such as polyvinyl alcohol and polyvinylpyrrolidone. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the underlying charge transport layer or undercoat layer.

Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and dichlorohexanone, and N,N-dimethylformamide and N,N-dimethylacetamide. Amides, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene oxide, dichloroethylene, carbon tetrachloride, trichloroethylene, etc. aliphatic halogenated hydrocarbons or benzene, toluene,
Aromatics such as xylene, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating is done by dip coating method, spray coating method,
spinner coating method, bead coach ink method, Meyer bar coating method, blade coating method,
This can be carried out using a coating method such as 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 is performed at a temperature of 30 to 200°C for 5 minutes to 2 minutes.
It can be carried out stationary or under ventilation for 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 receiving charge carriers injected from the charge generation layer in the presence of an electric field, and transporting these charge carriers to the surface. have. At this time, the charge transport layer may be laminated on or below the charge generation layer.

Charge transport substances include electron transport substances and hole transport substances, and electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4.7-)dinitro-9-fluorenone, 2,
．． 4,5,7-tetranitro-9-fluorenone,
2,4.7-)nitro-9-dicyanomethylenefluorenone, 2゜4.5.7-titranitroxanthone, 2
, 4°8-trinidrothioxanthone, and polymers of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole, and N-methyl-N-
7enylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ditylphenothiazine, N,N-diphenylhydrazino-3-methylidene-10-ditylphenoxazine, p-pyrrolidinobenzaldehyde-N,N
Hydrazones such as -diphenylhydrazone, 1.33-)dimethylindolenine-ω-aldehyde-1N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 1-
[Pyridyl (2)] -3-(α-Methyl-P-diethyl 7-minostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-diphenyl-3-(p-diethyl 7-minostyryl)-4-methyl-5 -(P-diethylaminophenyl)pyrazoline, 1-phenyl-3-(α-
benzyl-P-diethylaminostyryl)-5-(p-
pyrazolines such as diethylaminophenyl)pyrazoline and spiropyrazoline, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-
Oxazole compounds such as (p-diethylaminophenyl)-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, thiazole compounds such as 2-(p-diethylaminostyryl)-6-diethylaminopenzothiazole compounds, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N,N
-diethylamino-2-methylphenyl)hebutane, 1
．． L, polyarylalkanes such as 2,2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, Examples include poly-9-vinylanthracene, pyrene-formaldehyde resin, and ethylcarbazole 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 film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include acrylic resin,
Insulating resins such as polyarylate, polyester, polycarbonate polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N-vinylcarbazole, polyvinylanthracene , organic photoconductive polymers such as polyvinylpyrene, and the like.

The charge transport layer has a limit in its ability to transport charge carriers, so it cannot be made thicker than necessary. Generally, the thickness is 5 to 307T, but the preferred range is 10 to 2T.
It is 5 ru. When forming the charge transport layer by coating, an appropriate coating method as 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 substrate having a conductive layer. As the base having a conductive layer, the base itself has conductivity,
For example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium,
Nickel, indium, gold, platinum, etc. can be used, and other materials include plastics having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluorinated ethylene, etc.), conductive particles (e.g., aluminum powder, titanium oxide, tin oxide, zinc oxide, carbon black, silver particles, etc.) together with a suitable binder. Plastic or a substrate coated on the conductive substrate, a substrate in which plastic or paper is impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used.

A subbing layer having a barrier function and an adhesive function can also be provided between the conductive layer and the photosensitive layer.

The subbing layer is formed from casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. can.

The thickness of the subbing layer is 0.1 to 10 μl, preferably 0.5 to 10 μl.
5IL is appropriate.

When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, if the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and after charging When exposed to light, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface and neutralize the positive charge, resulting in attenuation of the surface potential and an electrostatic contrast between the exposed area and the unexposed area. occurs.

A visible image is obtained by developing the electrostatic latent image thus formed with a negatively charged toner. Fix this directly or
Alternatively, the toner image can be transferred to paper or plastic film, developed, and fixed.

After transferring the electrostatic latent image on the photoreceptor to the insulating layer of transfer paper,
A method of developing and fixing can also be used. The type of developer, developing method, and fixing method may be any known developer or known method, and are not limited to a specific one.

On the other hand, when the charge transport material is a hole transport material, the surface of the charge transport layer must be negatively charged, and 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 an attenuation of the surface potential and an electrostatic contrast with 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 a conductive layer, a charge transport layer, and a charge generation layer are laminated in this order, if the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged, and after charging, When exposed to light, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed portion, and then reach the substrate.

On the other hand, holes generated in the charge generation layer reach the surface and the surface potential is attenuated, creating electrostatic contrast with the unexposed area.

A visible image is obtained by developing the electrostatic latent image thus formed with a positively charged toner. Fix this directly or
Alternatively, the toner image can be transferred to paper or plastic film, developed, and fixed.

After transferring the electrostatic latent image on the photoreceptor to the insulating layer of transfer paper,
A method of developing and fixing can also be used. The type of developer, developing method, and fixing method may be any known developer or known method, and are not limited to a specific one.

For a trowel, when the charge transport layer is made of a hole transporting substance, it is necessary to positively charge the surface of the charge generation layer, and when exposed to light after charging, the holes generated in the charge generation layer are released in the exposed area. It is injected into the charge transport layer and then reaches the substrate.

On the other hand, the electrons generated in the charge generation layer reach the surface and the surface 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, as the electrophotographic photoreceptor of the present invention, there can be mentioned an electrophotographic photoreceptor containing the above-mentioned azo pigment and a charge transporting substance in the same layer.

In this case, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used in addition to the charge transport substance.

The electrophotographic photoreceptor of this example can be prepared by dispersing the above-mentioned azo pigment and charge transfer complex compound in a polyester solution dissolved in tetrahydrofuran, and then forming a film thereon.

The pigment used in any of the electrophotographic photoreceptors contains at least one type of pigment selected from azo pigments having an organic residue represented by the general formula (I), and its crystal form can be amorphous, crystalline, etc. Either is fine.

In addition, if necessary, pigments having different light absorptions may be used in combination to increase the sensitivity of the photoreceptor or to obtain a panchromatic photoreceptor, etc. It is also possible to use a combination of two or more types of azo pigments, or a combination with 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 digital electrophotographic copying machines, laser beam printers, CRT printers, LED printers, liquid crystal printers, laser plate making, etc. The recording system can also be widely used in many electrophotographic applications.

[Example] Examples 1 to 15 Ammonia aqueous solution of casein (casein 1
1.2% ammonia water, 1 g of ammonia water, 222 mJL of water) was dried with a Mayer bar, and the film thickness was 1.2%. It was applied as OIL and dried.

Next, 5 g of the exemplary pigment (2)-1 was added to 95 m of ethanol.
Butyral resin (butyralization degree 61 mol%) 2 for J1
g was added to the dissolved liquid and dispersed in a sand mill for 2 hours. This dispersion was applied onto the previously formed casein layer using a Mayer bar so that the film thickness after drying would be 0.5 JL, and dried to form a charge generation layer.

Next, p-diethylaminobenzaldehyde-N-α-
5 g of naphthyl-N-phenylhydrazone and 5 g of polymethyl methacrylate (number average molecular weight 10,000) were added to 7 g of benzene.
This liquid was applied onto the charge generation layer using a Mayer bar so that the film thickness after drying was 19 layers, and dried to form a charge transport layer. Created.

Electrophotographic photoreceptors corresponding to Examples 2 to 15 were prepared by replacing the azo pigment with Exemplary Pigment (2)-1 and using the following exemplified pigment, and with the other conditions being the same as in Example 1. .

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Kawaguchi Electric Co., Ltd. Model SP-).
428) in a static manner at -5.5 KV, held in a dark place for 1 second, and then exposed to light at an illuminance of 2 lux to examine charging characteristics.

The charging characteristics include the surface potential (Vo) and the amount of light exposure (El) required to attenuate the potential to 172 when dark decaying for 1 second
/2) was measured. Show the results.

, V −V El/2 1uxsea
=1 (2)-17002,0 2(1)-116803,8 3 Synthesis Example 2 Pigment 700 1.8 4 (2)-27102,0 5(2)-87002,5 6(2)-156901,8 7(2)-256802,0 8(2)-277002,2 9(2)-306702,0 10(2)-826101,9 11(2)-386002,3 12(2)-486201,8 13( 3)-16102,0 14(3)-77303,4 15(4)-27103,8 Comparative Example Completely the same method as Example 1 except that the azo pigment in Example 1 was replaced with an azo pigment having the following structural formula. A photoreceptor was prepared and the measurement results are shown in □.

Pigments used in comparative examples Comparative example 2 Comparative example 4 Comparative example 5 CO Comparative example 6 1 720 6.6 2 600 2.5 3 680 7°5 4 360 18.0 5 500 15.0 6 680 5.2 Above From the results, it is recognized that all the electrophotographic photoreceptors of the present invention have sufficient charging ability and sensitivity.

Further, using the electrophotographic photosensitive pairs prepared in Examples 1.4, 6, 7.12.13, variations in bright area potential and dark area potential during repeated use were measured.

In the measurement method, a photoreceptor was fogged in the cylinder of an electrophotographic copying machine equipped with a -5.5 KV corona charger, an exposure optical system, a developer, a transfer charger, an auxiliary exposure optical system, and a cleaner. This copying machine is configured to produce an image on transfer paper as a cylinder is driven.

Using this copier, the initial bright area potential (VL) and dark area potential (Vo) were set to around 100V and -700V, respectively, and the bright area potential (VL) after 5,000 uses was set.
) and dark potential (Vo) were measured. Show the results.

Example 1 700 110/l 6
700 11.0// l 2
700 110 Example 1
710 125/l 6
720 130tt 7
700 110/lL2
730 115 Regarding the photoconductor prepared in Comparative Example 6, the potential characteristics were repeatedly evaluated in the same manner as above, and the potential characteristics varied as shown below.

Initial potential VD: -700V, VL knee 100V after 5,000 cycles VD knee 500V, VL knee 200V From the above results, the electrophotographic photoreceptor of the present invention has excellent potential stability during repeated use. was recognized.

Examples 16-24 5 g of the above exemplary pigment (2)-45 was added to 95 mJl of methyl isobutyl ketone with benzal resin (synthesized from benzal and poval with a degree of polymerization of 500, degree of benzalization 70%) 2
g was added to the dissolved liquid and dispersed in a sand mill for 6 hours. After drying this dispersion on an aluminum plate, the film thickness was 0.5. A charge generation layer was formed by coating with a Mayer bar and drying.

5 g of a stilbene-based compound and 5 g of polymethyl methacrylate (number average molecular weight: 100,000) were dissolved in 70 rnl of benzene, and this solution was applied onto the charge generation layer so that the film thickness after drying was 19%.
The electrophotographic photoreceptor of Example 16 was prepared by coating with a Mayer bar and drying to form a charge transport layer.

Electrophotographic photoreceptors corresponding to Examples 17 to 24 were prepared in the same manner as in Example 16, except that the azo pigment was replaced with Exemplified Pigment (2)-45 and the following exemplified pigment was used.

The electrophotographic photoreceptor produced in this way was
The semiconductor laser and its scanning unit were replaced with a tungsten light source, and corona charging was performed statically at -5.5 KV using an electrostatic copying paper tester (modified model of the 5P-428 mentioned above), and the test was carried out in the dark. After holding it for 1 second, it was exposed to laser light and the charging characteristics were examined.

The charging characteristics include the surface potential (Vo) and the exposure amount (E1) required to attenuate the potential to 175 after dark decaying for 1 second.
15) was measured. Show the results.

Examples Illustrative pigment Vo (-V) E115 (g
J/c♂)16 (2)-457007,0 17(2)-577208,1 18(2)-886807,4 19(2)-937007,8 20(2)-986707,6 21(3)- 27108,2 22(3)-77007,4 23(4)-17107,2 24(4)-46808,0 From the above results, 1. The electrophotographic photoreceptor of the present invention has a practically sufficient resistance to laser light. It is clear that it has excellent sensitivity and potential characteristics.

Example 25 5 g of 2,4.7-dolinitro-9-fluorenone and poly-4,4°-dioxydiphenyl-2,2-propane carbonate (molecular weight: 300,000) were placed on the charge generation layer prepared in Example 1. The coating amount after drying the coating solution prepared by dissolving 5g in 70mJl of tetrahydrofuran is 10g7m2
It was applied and dried.

The charging characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1.

The charging polarity at this time was set to 10. Show the results.

vO: +680V.

El/2: 4.5uux, sec Example 26 Ammonia aqueous solution of casein (casein 1142%, aqueous ammonia Ig, water 222%) was placed on an aluminum cylinder.
M) was applied using a dip coating method and dried to form a subbing layer with a coating weight of 1.0 g/m2.

Next, 1 part by weight of Exemplary Pigment (2)-41, 1 part by weight of butyral resin (trade name: Eslec BM-2,9 manufactured by Mizu Kagaku 2), and 30 parts by weight of isopropyl alcohol were dispersed in a ball mill for 4 hours.

This dispersion was applied onto the previously formed subbing layer by a dip coating method and dried to form a charge generating layer. The film thickness is 0.3. Met.

Next, 1 part by weight of 4-diphenylamino-4''-methoxystilbene, polysulfone (trade name PI700, UCC
Company-made) 1! l! parts by weight and 6 parts by weight of monochlorobenzene were mixed and stirred and dissolved using a stirrer.

This liquid was applied onto the electrogenerating layer by a dip coating method and dried to form a charge transport layer. The film thickness was lap.

The thus prepared electrophotographic photoreceptor was subjected to corona discharge of −5, 2 and 3. The surface potential at this time was measured (initial potential Vo), and the surface potential after the photoreceptor was left in the dark for 5 seconds was measured (dark decay VK).

Sensitivity was evaluated by measuring the exposure amount (El/2#LJ/cm 2 ) required to attenuate the potential vK to 1/2 after dark decay.

At this time, the light source was a three-element semiconductor laser of gallium/aluminum/silicon (output 5 mW, oscillation wavelength 780 nm).
) was used. Show the results.

Vony 700V, potential retention rate = 94%, E L / 2: 8, 4 g J / cm
2. Next, the above photoreceptor was replaced with an LBP-CX photoreceptor and set in a laser beam printer (trade name: LBP-CX, manufactured by Canon ■), which is a reversal development type electrophotographic printer equipped with the above semiconductor laser. , through real image format testing.

The conditions were: -700V surface potential after secondary charging, -150V surface potential after image exposure (exposure amount 1.21LJ/cm2),
Transfer potential +700V, developer polarity negative, process speed 50mm/sec, development conditions (development bias) -
450V, image exposure scanning method is image scan, -
Next pre-charging exposure: Full red exposure at 50 Jlux, sec. Image format was line scanning of a laser beam in accordance with character and image signals, and good prints of both characters and images were obtained.

Example 27 A polyvinyl alcohol film having a thickness of 0.5 pL was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

Next, the azo pigment dispersion used in Example 1 was placed on the polyvinyl alcohol layer formed previously so that the film thickness after drying was 0.5.
A charge generating layer was formed by coating with a Mayer bar and drying to form a charge generating layer.

Next, 5 g of 1-[pyridyl(2)]-3-(,α-methyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline and polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) were added. ) was dissolved in 70 mM of tetrahydrofuran and applied onto the charge generation layer so that the film thickness after dry MI would be 15%, and dried to form a charge transport layer.

The charging characteristics and durability characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as described in Example 1.

Show the results.

vow-690, El/2: 4.01ux, see Durability characteristics Initial Vo: -700, VL: -100
VD knee 680 after 5,000 cycles. VL knee 130V From the above results, it was recognized that both sensitivity and potential stability during long-term use were good.

Example 28 An ammonia aqueous solution of casein (described above) was applied onto a 100 mm thick aluminum plate and dried to form a subbing layer with a thickness of 0.5 mm.

Next, 5 g of 2,4.7-dolinitro-9-fluorenone
and 5 g of poly-N-vinylcarbazole (number average molecular weight: 300,000) were dissolved in 70 ml of tetrahydrofuran to form a charge transfer complex compound.

This charge transfer complex compound and exemplary pigment (2)-45-1
5g of polyester (product name Byron, manufactured by Toyobo ■)
was added to a solution of 70ml of tetrahydrofuran and dispersed. The film thickness after drying this dispersion liquid on the undercoat layer is 14.
I applied it in a river pattern and let it dry. The charging characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1.

However, the charging polarity was set to 10. Show the results.

V□: +680°El/2: 4.01ux, sec Example 29 The same charge transport layer and charge generation layer as in Example 1 were placed on the casein layer of the casein layer-coated aluminum substrate used in Example 1. A photosensitive layer was formed in the same manner as in Example 1 except that the layers were sequentially laminated and the structure of one layer was different, thereby producing an electrophotographic photoreceptor.

Charging characteristics were measured in the same manner as in Example 1.

However, the charging polarity was set to 10. Show the results.

vo: +680° El/2: 4.2uux, sec.

Further, potential stability during durable use was evaluated in the same manner as in Example 27 except that the charging polarity was changed to 10. Initial durability Vo: +700. VL: +110V After 5,000 cycles of durability, Vo: +685, VL: +120V.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention uses a specific azo pigment in the photosensitive layer, so that either or both of carrier generation efficiency and carrier transport efficiency within the photosensitive layer containing the azo pigment is improved. It exhibits remarkable effects such as improved sensitivity and potential stability during long-term use, and sensitivity even in the long wavelength range.

Claims (6)

[Claims] (1) On the conductive support, there is a general formula▲mathematical formula, chemical formula, table, etc.▼(I) (In the formula, R_1 and R_2 are the same or different,
Hydrogen atom, a halogen atom, a aryl group having a nitro group or cyano group as a substituent, a heterocyclic group which may have a substituent, and X represents a hydrogen atom or a halogen atom). is characterized by having a photosensitive layer containing an azo pigment having a structure bonded to an aromatic hydrocarbon ring or aromatic heterocycle which may have a substituent which may be bonded via a bonding group. Electrophotographic photoreceptor. (2) The azo pigment has the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (II) (In the formula, R_1, R_2 and X have the same meaning as R_1, R_2 and X in the general formula (I), and Ar is a bond. An azo pigment represented by an aromatic hydrocarbon ring or an aromatic heterocycle which may have a substituent which may be bonded via a group, n is an integer of 1, 2, 3 or 4. An electrophotographic photoreceptor according to claim 1. (3) The azo pigment has at least one organic residue selected from the organic residues represented by the general formula (I) and the general formula -H=N-Cp(III ) (wherein, Cp is phenolic O
An aromatic hydrocarbon ring which may have a substituent which may be bonded via a bonding group in the same molecule to at least one of the organic residues represented by ), which represents a coupler residue having an H group. The electrophotographic photoreceptor according to claim 1 or 2, which is an azo pigment having a structure bonded to an aromatic heterocycle. (4) Azo pigment has the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (IV) (In the formula, R_1, R_2 and X are synonymous with R_1, R_2 and X in general formula (I), Ar and n is synonymous with Ar and n in general formula (II), R_3 represents a halogen atom, nitro group, or cyano group, and m is 1 to 5
3. The electrophotographic photoreceptor according to claim 1 or 2, which is an azo pigment represented by the following integer (integer up to, but not necessarily the same substituent when it is 2 or more). (5) Claims in which the photosensitive layer contains at least one azo pigment represented by general formula (II) or (IV) and at least one azo pigment according to claim 3. 2. The electrophotographic photoreceptor according to item 1. (6) The conductive layer and the organic residue represented by the general formula (I) are
At least three of a charge generation layer and a charge transport layer containing an azo pigment having a structure bonded to an aromatic hydrocarbon ring or an aromatic heterocycle which may have a substituent which may be bonded via a bonding group. The electrophotographic photoreceptor according to claim 1, which comprises a layer.