JPH01100559A - 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 Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a trisazo pigment having a specific molecular structure in a photosensitive layer.

[Prior Art] Pigments and dyes exhibiting photoconductivity have been published in numerous publications.

For example, “RCA Rev ew” Vo1.23
, P, 413-F, 419 (1962, 9), the photoconductivity of phthalocyanine pigments was announced, and an electrophotographic photoreceptor using this phthalocyanine pigment was disclosed in U.S. Patent No. 3,397°086. and US Pat. No. 3,816,118. In addition, organic semiconductors used in electrophotographic photoreceptors include:
For example, U.S. Pat. No. 4,315,983, U.S. Pat. No. 3,427,189 and "Rese
a ch Disclosure”20517 (1
Pyrylium dyes shown in US Pat. No. 3,824,099, methine squaric acid dyes shown in US Pat. No. 3,824,099, US Pat.
Examples include disazo pigments shown in US Patent No. 4,251.613 and the like.

Such organic photoconductors are easier to synthesize than inorganic photoconductors, and the visible light sensitivity can be changed relatively easily in the wavelength range through molecular design, making it easy to control color sensitivity. It is highly efficient, non-polluting, and far superior in terms of productivity and economy compared to inorganic semiconductors.
In recent years, various companies have been competing with each other to speed up development, and although many products have reached the level of practical use in terms of sensitivity and durability, improvements are still required.

On the other hand, in recent years, these organic photoconductors have been
There has been a rapid increase in demand for extending the photosensitive wavelength range to around 0.00 nm (which is the most preferable in terms of economy, output, and matching with photosensitive materials), and for use as photoreceptors for digital recording such as laser printers. Considering conventional organic photoconductors from this point of view, the above-mentioned phthalocyanine pigment, an improved aluminum phthalocyanine pigment shown in U.S. Pat. No. 4,426,434, and U.S. Pat. No. 4,436 , 800, and the triphenylamine trisazo pigments shown in U.S. Pat. No. 4,439,506, and U.S. Pat. No. 4,447,
Tetrakisazo pigments, such as those shown in No. 513, have been proposed as photoconductors for semiconductor lasers.

However, when using an organic photoconductor as a photoreceptor for a semiconductor laser, firstly, the photosensitive wavelength range must extend to long wavelengths, secondly, the sensitivity and durability must be good, and depending on the usage and temperature, the semiconductor Since the wavelength of the laser changes, it is necessary to have constant sensitivity over a wide wavelength range and also to have good productivity. The organic photoconductors mentioned above do not fully satisfy these conditions.

As a result of extensive research and development, the present inventors have found that by using the trisazo pigment represented by the general formula (1) described below, it has been found that it is not only useful as an electrophotographic photoreceptor for fishing boats, but also as a near-infrared photoreceptor. We have succeeded in producing an organic photoconductor that fully satisfies the above conditions as a photoconductor.

[Problems to be Solved by the Invention] The first purpose of the present invention is to provide a new electrophotographic photoreceptor, and the second purpose is to provide a practical high sensitivity characteristic in the visible range and stability during repeated use. The second purpose is to provide a new photoconductor for near-infrared light, and the fourth purpose is to provide a photoconductor for use in digital recording such as laser copying, laser beam printers, and LED printers. An object of the present invention is to provide an electrophotographic photoreceptor that has practical high sensitivity characteristics and stable potential characteristics during repeated use in a process using the photoreceptor.

[Means for Solving Problems and Effects] The present invention comprises an electrophotographic photoreceptor characterized in that a photosensitive layer contains a trisazo pigment represented by the following general formula.

In the formula, R1 to R3 represent a hydrogen atom, an alkyl group or a halogen atom, and A represents a coupler residue having a phenolic hydroxyl group.

Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl, and halogen atoms such as chlorine, bromine, fluorine, and iodine atoms.

A represents a coupler residue having a phenolic hydroxyl group,
Examples include residues represented by the following general formulas (2) to (8).

p.

In the formula, it represents a residue that forms a polycyclic aromatic ring or a heterocycle by condensing with a benzene ring, and may have a substituent.

R4 and R5 represent a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a heterocyclic group which may have a substituent, or a residue which together with a nitrogen atom forms a cyclic amine group.

R6 and R7 represent an alkyl group, an aralkyl group, or an aryl group which may have a substituent.

Y represents a divalent group of an aromatic hydrocarbon or a residue that forms a divalent heterocyclic group together with a nitrogen atom, and may have a substituent.

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

R9 and Fho are alkyl groups that may have substituents,
It represents an aralkyl group, an aryl group, a heterocyclic group, or a residue which together with the nitrogen atom forms a cyclic amino group.

Examples of the polycyclic aromatic ring or heterocycle formed by condensation with X include naphthalene, anthracene, carbazole, benzcarbazole, dibenzofuran, benzonaphthofuran, and diphenylene sulfide rings.

In R4 and R5, as an alkyl group.

Examples include groups such as methyl, ethyl, propyl, and butyl; examples of aralkyl groups include groups such as benzyl, phenethyl, and naphthylmethyl; and examples of aryl groups include phenyl, diphenyl, naphthyl,
Examples of the heterocyclic group include groups such as anthryl, and examples of the heterocyclic group include carbazole, dibenzofuran, benzimidacylone, benzthiazole, thiazole, and pyridine.

Specific examples of R, and R7 include the same groups as those exemplified for R4 and R5 above.

Specific examples of Y include monocyclic aromatic hydrocarbon groups such as 0-phenylene, 0-
naphthylene, perinaphthylene, l,2-antrylene,
Examples include fused polycyclic aromatic hydrocarbon groups such as 9.10-phenanthrylene. Also, together with the nitrogen atom, 2
Examples of valent heterocycles include 3,4-pyrazolediyl group, 2,3-pyridinediyl group, 4,5-pyrimidinediyl group, 6.7-indazolediyl group, 5.6-
Examples include 5- to 6-membered heterocyclic divalent groups such as benzimidazolediyl group and 6,7-chiralindiyl group.

Examples of the aryl group or heterocyclic group for R8 include phenyl, naphthyl, anthryl, pyrenyl, pyridyl, thienyl, furyl, carbazolyl, and the like.

Specific examples of the alkyl group, aralkyl group, and aryl group in R9 and Rlo include the same groups as mentioned above, and examples of the heterocyclic group include groups such as carbazole, dibenzofuran, benzimidacylon, benzthiazole, thiazole, and pyridine. It will be done.

Examples of substituents that the groups represented by X, R4 to RLo above may have include halogen atoms such as fluorine atom, chlorine atom, iodine atom, and bromine atom, and alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl. , methoxy,
Alkoxy groups such as ethoxy, propoxy, phenoxy, nitro groups, cyano groups, dimethylamino, dibenzylamino.

Examples include groups selected from substituted amino groups such as diphenylamino, morpholino, piperidino, and pyrrolidino.

In particular, the effect is remarkable when A is a residue represented by the following general formula (9), and the effect is greatest when RL8 is an ethyl group at the ortho position in the residue represented by the following general formula (1o).

In the formula, R11 is the same group as R4, or an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, or forms a 5- to 6-membered ring together with the carbon atoms to which it is bonded. ), R12, R13, 1
'h4 and R15 represent a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a trifluoromethyl group, a cyano group, an alkyl group, an alkoxy group, or an aryl group, an aralkyl group, or an amine group that may have a substituent; , R12
and R13, R13 and R14, and R14 and R15 may form a fused aromatic ring together with a part of the carbazole ring.

In the formula, RlB and R19 are hydrogen atoms, halogen atoms,
It represents a nitro group, trifluoromethyl group, cyan group, or an alkyl group that may have a substituent, an allyl group, an alkoxy group, and an amino group.

Although the present invention is not bound by theory,
Since there is almost no degree of freedom in the central part of the skeleton of the trisazo pigment represented by general formula (1), it is thought that charge transfer between molecules is considerably improved by 1, and as a result, the absorption wavelength is extended to longer wavelengths. can be expected. Therefore, the general formula (1
) By incorporating the trisazo pigment shown in the photosensitive layer, either or both of charge carrier generation efficiency and charge carrier transport efficiency become good, improving sensitivity and ensuring potential stability during long-term use. It turns out.

All of the electrophotographic photoreceptors using the trisazo pigment represented by the general formula (1) of the present invention have good sensitivity and potential stability during long-term use, and the photosensitive liquid also tends to have longer wavelengths. However, especially when A in general formula (1) is a residue represented by general formula (10), the wavelength becomes significantly longer, and most have sensitivity up to 750 nm or more, and some have sensitivity up to 800 nm.
There are many that exceed m.

By using the trisazo pigment of the present invention in an organic photoconductor, higher sensitivity and/or longer wavelength sensitivity can be achieved, resulting in applications such as high-speed copying machines, laser beam printers, LED printers, liquid crystal printers, etc. It has become possible to apply this method, and since a more stable potential is ensured, it has become possible to obtain stable and beautiful images even in a single image.

Representative examples of the trisazo pigment represented by the general formula (1) are illustrated below.

Exemplary pigment (1) Coupler residue: Exemplary pigment (2) Central skeleton: Same as above Exemplary pigment (3) Central skeleton: Same as above Coupler residue: Exemplary pigment (4) Central skeleton: Same as above Exemplary pigment (5) Central skeleton 2 Same as above coupler Residues: Exemplary pigment (6) Central skeleton: Exemplary pigment (7) as above Central skeleton: Exemplary pigment (8) as above Central skeleton: Exemplary coupler residue as above: Exemplary pigment (9) Central skeleton two as above Coupler residue: X Exemplary Pigment (10) Central skeleton: Same as above coupler residue: Exemplary pigment (11) Central skeleton: Two same as above coupler residue: Exemplary pigment (12) Central skeleton: Same as above coupler residue (13) Central skeleton: Same as above coupler residue: Example Pigment (14) Exemplary pigment (15) Central skeleton: Same as above N Exemplary pigment (16) Central skeleton: Same as above Exemplary pigment (17) Central skeleton: Same as above Coupler residue: Exemplary pigment (18) Central skeleton: Same as above Exemplary pigment (19) ) Central skeleton: Exemplified pigments as above (20) Central skeleton: Exemplified coupler residues as above: Exemplary pigments (21) Central skeleton: Exemplified pigments as above (22) Central skeleton 2 Id. coupler residues: Exemplified pigments (23) Pigment (24) Exemplified pigment with central skeleton 2 (25) Exemplified pigment with central skeleton 2 (26) Exemplified pigment with 2 central skeleton (27) Central skeleton: Residue of the above coupler: Exemplary pigment (28) Central skeleton: Remain of the above coupler Group: Exemplified Pigment (29) Central Skeleton II Illustrated Pigment (30) Central Skeleton II Illustrated Pigment (31) Central Skeleton II Illustrated Pigment (32) Central Skeleton Exemplified Pigment (33) Central Skeleton II Illustrated Pigment ( 34) Central skeleton: Same as above Exemplary pigment (35) Central skeleton: Two same as above Exemplary pigment (36) Central skeleton: Two same as above Exemplary pigment (37) Central skeleton: Same as above H Exemplary pigment (38) (]) I Exemplary pigment (39) Center Skeleton 2 Same as above UI'I Exemplary pigment (40) Central skeleton: Same as above Skeleton: Exemplified Pigment (45) Central Skeleton: Exemplified Pigment (46) Exemplified Pigment (47) Central Skeleton: Exemplified Pigment (48) Central Skeleton II Coupler Residue: Exemplified Pigment (49) Residue of Central Skeleton II Coupler Group: Central skeleton: Coupler residue nide as above These trisazo pigments represented by general formula (1) can be used alone or in combination of two or more.

The trisazo pigment represented by the general formula (1) is produced by, for example, treating an amine represented by the following structural formula with a nitrite salt to form hexazonium in a conventional manner.

Then the following general formulas (11), (12), (13)% formula%
(17) Aqueous coupling of the coupler represented by "x" (wherein R4-, R10, Alternatively, once isolated in the form of zinc chloride double salt, etc., a suitable solvent such as N
, N-dimethylformamide, dimethyl sulfoxide, or the like in the presence of an alkali.

Synthesis example [Example pigment (1)] 80 mA of water and 16.6 mM of concentrated hydrochloric acid in a 500 mA beaker
(0.19 mol) and while cooling in an ice water bath, 10.67 g (0.19 mol) of amine having the above structural formula was added.

029 mol) was added thereto, and the liquid temperature was brought to 3°C while stirring.

Next, add 6.3 g (0,0915 mol) of sodium nitrite to 1 mol of water.
A solution dissolved in 0 ml of the solution was added dropwise over 10 minutes while controlling the liquid temperature to 5°C or less, and after the dropwise addition was completed, the solution was stirred for an additional 30 minutes at the same temperature. Carbon was added to the reaction solution and the mixture was filtered to obtain a hexazation solution.

Next, put 70 ml of N,N-dimethylformamide into a beaker.
79.5 g (0.80 mol) of triethylamine was added, and 34.8 g of 2-hydroxy-8-fluoro-3-benzaazirittaic acid-2'-,=c-tylanilide was added.
g (0,0915 mol) was added and dissolved. This coupler solution was cooled to 5°C, and while controlling the liquid temperature at 5 to 10°C, the above hexazidation solution was added dropwise with stirring over 30 minutes, then stirred at room temperature for 2 hours, and then left overnight. did. After filtering the reaction solution, it was washed and filtered with water to obtain a water paste containing 40.3 g of assembled pigment in terms of solid content.
Stirring and filtration were repeated four times at room temperature using Jl N,N-dimethylformamide. Thereafter, stirring and filtration were repeated twice each with 400 mA of methyl ethyl ketone, followed by drying under reduced pressure at room temperature to obtain 39.1 g of purified pigment.

Yield: 87.6%, elemental analysis above decomposition point 250°C
Calculated value (%) Experimental value (%) C74,9074,1
5 H3,903,72 N 11.83 11.31 Although the method for synthesizing one typical pigment has been described above, other trisazo pigments represented by general formula (1) can be synthesized in the same manner.

A coating containing the trisazo pigment represented by the general formula (1) exhibits photoconductivity, and therefore can be used in the photosensitive layer of an electrophotographic photoreceptor.

That is, in a specific example of the present invention, an electrophotographic photoreceptor can be prepared by dispersing and containing the trisazo pigment represented by the general formula (1) in a suitable binder on a conductive support to form a film. .

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 photoconductive trisazo pigment as possible to obtain sufficient absorbance;
In addition, 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 µl or less, preferably 0.01 to 1 µl, is used. It is preferable that

This means that most of the incident light is absorbed by the charge generation layer and generates a large number of charge carriers, and that the generated carriers must be injected into the charge transport layer without being deactivated by recombination or trapping. It is caused by something.

The charge generation layer can be formed by dispersing the trisazo pigment in a suitable binder and coating it on the conductive substrate.

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,
Examples include insulating resins such as polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, polyurethane, epoxy resin, casein, 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 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. At this time, this charge transport layer may be laminated on or under the charge generation layer.

When a charge transport layer is formed on a charge generation layer, the substance that transports charge carriers in the charge transport layer (hereinafter referred to as charge transport material) is substantially in the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. Preferably, it is insensitive. The electromagnetic waves referred to here include gamma rays, X-rays, ultraviolet rays, visible light,
Includes a broad definition of light that includes near-infrared, infrared, far-infrared, etc.

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.

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,
5.7-tetranitro-9-fluorenone, 2,4,5
．． Examples include electron-withdrawing substances such as 7-titranitroxanthone and 2,4.8-trinidrothioxanthone, and polymerized versions of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, and N,N-diphenylhydrazino-3-methylidene-10-ditylphenothiazine. , p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-pyrrolidinobenzaldehyde-N.

Hydrazones such as N-diphenylhydrazone, p-diethylhenzaldehyde 3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1- Phenyl-3-(p-chloroethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(
p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(3)]-
3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2
)] -3-(p-diethylaminostyryl)-4-
Methyl-5-(p-diethylaminophenyl)pyrazoline, l-phenyl-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)
Pyrazolines such as pyrazoline and spiropyrazoline, 2
-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(P-dimethylaminophenyl)-5-(
Oxazole compounds such as 2-chlorophenyl)oxazole, 2-(P-diethylaminostyryl)-6-
Thiazole compounds such as dinithylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1.1bis(4-N.

N-diethylamino-2-methylphenyl)hebutane,
Polyarylalkanes such as 1,1,2.2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, stilbene derivatives,
Poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinyl acridine, poly-
Examples include 9-vinylphecoanthracene, 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 materials 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,
polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer,
Examples include insulating resins such as acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, and organic photoconductive polymers such as polyN-vinyllunobesol, 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. -For boat fishing, 5 to 30 units are required, but the preferred range is 8 to 207 L.
It is. When forming the charge transport layer by coating, an appropriate coating method 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. Examples of the substrate having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc,
Stainless steel, nickel, molybdenum, chromium, titanium, nickel, indium, gold and platinum can be used, and in addition, aluminum, aluminum alloys, indium oxide, tin oxide, indium oxide-tin oxide alloys, etc. can be used by vacuum evaporation method. plastics (e.g. polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.), conductive particles (e.g. aluminum powder, titanium oxide, carbon black, silver particles, etc.) A substrate coated on a plastic or conductive substrate together with a suitable binder, a substrate obtained by impregnating a plastic or paper with conductive particles, a plastic containing a conductive polymer, etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive substrate and the photosensitive layer.

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

It can be formed from aluminum oxide, etc. The appropriate thickness of the undercoat layer is 0.1 to 5 JL, preferably 0.5 to 3 JL.

When using a photoreceptor in which a conductive substrate, a charge generation layer, and a charge transport layer are laminated in this order, and 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 charges, resulting in attenuation of the surface potential.
Electrostatic contrast occurs between the exposed area and the unexposed area.

A visible image is 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 or plastic film 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 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 charge, 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 when an electron transporting substance is used.

When using an electrophotographic photoreceptor in which a conductive substrate, a charge transport layer, and a charge generation layer are laminated in this order, when the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged. When exposed to light after charging, the electrons generated in the charge generation layer in the exposed area are injected into the charge transport layer and then reach the substrate. On the other hand, holes generated in the charge generation layer reach the surface, attenuation of the surface potential occurs, and electrostatic contrast occurs between the layer and the unexposed area. A visible image is 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 or plastic film 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 transport material consists of a hole transport material, it is necessary to charge the surface of the charge generation layer positively, 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 substrate. On the other hand, electrons generated in the charge generation layer reach the surface, resulting in attenuation of the surface potential and electrostatic contrast between the charge generation layer and 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.

Furthermore, as another specific example of the present invention, the above general formula (1)
Examples include an electrophotographic photoreceptor containing a trisazo pigment represented by the following in the same layer together with a charge transporting substance. At this time, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used in addition to the above-mentioned charge transport substance.

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

The pigment used in any electrophotographic photoreceptor is at least one selected from trisazo pigments represented by general formula (1).
Contains different types of pigments. In addition, if necessary, pigments with different light absorptions 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 two or more types of trisazo pigments shown in the formula below, 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, and other near-infrared light sources. It can also be widely used in many electrophotographic applications of digital recording systems.

[Example] Examples 1 to 21 Ammonia aqueous solution of casein (casein 1
1.2 g of aqueous ammonia, 1 g of aqueous ammonia, 222 mJL of water) was applied using a Mayer bar so that the film thickness after drying was 1.0 L, and then dried.

Next, 5 g of the exemplified pigment (1) was added to 9 g of cyclohexanone.
5mM butyral resin (butyralization degree 63 mol%)
2 g was added to the dissolved liquid and dispersed with 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 was 0.5#L, and dried to form a charge generation layer.

5 g of hydrazone compound and 5 g of polycarbonate (number average molecular weight 40,000) were dissolved in 70 mu of benzene, and this was applied onto the charge generation layer using a Mayer bar so that the film thickness after drying was 20 mm, and dried. A charge transport layer was formed to produce an electrophotographic photoreceptor of Example 1.

Example 2 using the exemplified pigment described below in place of exemplified pigment (1)
Electrophotographic photoreceptors corresponding to Examples 1 to 21 were prepared in exactly the same manner.

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Model 5P-428, manufactured by Kawaguchi Denki ■).
Using a static method, corona charging was carried out at 15 KV, and after holding it for 1 second in a dark place, it was exposed to light with an illuminance of 2 lux,
The charging characteristics were investigated.

The charging characteristics include the surface potential (Vo) and the amount of exposure required to attenuate the potential to 1/2 (El/
2) was measured. The results will be described later.

Comparative Examples 1 to 5 In place of the pigment used in Example 1, electrophotographic photoreceptors were prepared in the same manner using an azo pigment having the structure shown below and synthesized in advance, and evaluated in the same manner. The results will be described later.

Comparative pigment (1) (Pigment described in JP-A-57-195767) Coupler residue: Comparative pigment (2) (Pigment described in JP-A-61-272754) Coupler residue: Comparative pigment (3) ( Pigment described in JP-A-61-43662) Central skeleton: -N-N-@-GOO-S- Comparative pigment (4) (Pigment described in JP-A-56-167759) Comparative pigment (5 ) (Pigment described in JP-A-55-69148) 1
(1) 700 1.52
(2) 710 1.43
(4) 710 1.64
(5) 710 1.7
5 (6) 705 1.
86 (9) 700 1
．． 97 (to) 680 1
．． 9g (12) 695 2
．． 09 (15) 7oo
2.010 (18) 705,
1.811 (19) 695
,． 2.312 (21) 715
2.113 (23) 700
1.914 (24) 70
5- 1.915 (25) 7
00 2.216 (30)
700 2.717 (31)
695 2.118 (32
) 885 2.219
(35) 705 2.120
(39) 710 2.0
21 (40) 695
1.81 (1) 700
2.02 (2) 705
3.73 (3) 700
2.24 (4) 700
2.75 (5) 700
6.2 From the above results, it is recognized that all the electrophotographic photoreceptors of the present invention have sufficient charging ability and sufficient sensitivity.

Comparative Example 1.3.5 and Examples 1 to 11 and Comparative Example 2.4
As can be seen from the comparison of Examples 12 to 15, the electrophotographic photoreceptor of the present invention has better results when the coupler residues represented by general formula (9) and general formula (2) are used. Shows sensitivity.

In particular, Comparative Example 1.3 and Example 1.2 are examples in which the couplers are the same and only the central skeleton is changed. Comparative Example 2.4 and Example 12
Comparing Comparative Example 3 and Example 3, it is clear that the electrophotographic photoreceptor of the present invention is superior in sensitivity.

Examples 22 to 32 5 g of exemplified pigment (3) was mixed with 95 m of methyl isobutyl ketone.
The mixture was added to a solution obtained by dissolving 2 g of benzal resin (synthesized from benzal and poval having a polymerization degree of 500, with a benzalization degree of 70 mol) in Jl and dispersed in a sand mill for 4 hours. This dispersion was applied onto an aluminum plate using a Mayer bar so that the film thickness after drying was 0.5 JL, and dried to form a charge generation layer.

5 g of a stilbene type compound and 5 g of polymethyl methacrylate (number average molecular weight 100,000) were dissolved in 70 mJl of benzene, and this was applied onto the charge generation layer using a Meyer bar so that the film thickness after drying was 18 mm. A charge transport layer was formed by drying, and an electrophotographic photoreceptor of Example 22 was prepared.

Example 2 Using the exemplified pigment described below in place of exemplified pigment (3)
Electrophotographic photoreceptors corresponding to Nos. 3 to 32 were prepared in exactly the same manner.

The electrophotographic photoreceptor produced in this way was
An interference filter is installed on the exposure axis, and the light source is set to 200W.
Electrostatic copying paper testing device (Mo
Del 5P-428, manufactured by Kawaguchi Denki ■) was used to statically corona charge the sample at 15 KV, hold it in a dark place for 1 second, and then expose it to laser light to examine the charging characteristics.

The charging characteristics include the surface potential (Vo) and the exposure amount (E11) required to attenuate the potential to 115 when attenuated for 1 second.
5) was measured. The results will be described later.

In addition, the spectral absorption rate of the photoreceptor was measured using an instantaneous multi-measurement detector MCPD-100 manufactured by Union Giken,
The ratio of the wavelength d that shows a steep fall in the spectral absorption waveform and the wave height at 800 nm and the wave height at 760 nm, that is, (Hλ800/Hλ760)X100
The photosensitive liquid Great Wall was evaluated based on the value of =F (flatness). Incidentally, the measured waveform of MCPD-Zoo and the above Mod'elSr- before modification while replacing the filter.
It shows very good agreement with the photosensitive waveform obtained using 428.

The above potential characteristics and the results of photosensitive liquid Great Wall measurement will be described later.

Comparative Examples 6 to 11 In place of the pigment used in Example 22, the comparative pigments (1) to
(5) and ε-type copper phthalocyanine [comparative pigment (6)]
A photoreceptor was prepared in the same manner using the same method, and evaluated in the same manner. The results will be described later.

22 (3) 890 1.20 811
0 4523 (1) 875 3.8
700 3524 (2) 880 3.5
710 482B (8) 875 2
．． 7 700 4827 (9) 1 (8
53,7E185 4530 (1B)
fl185 42 890 4531
(31) 890 23.1
835 032 (10) 88
0 4.4 8B5 45Et
(1) DO1,2578080?
(2) 885-580
08 (3) 880 9.8
f140 151] (4)
875-830 510
(5) 880 5.8
720 2511 (El) 8
80 8.5 770 40 From the above results, it can be seen that electrophotographic photoreceptors made of various pigments having coupler residues represented by general formula (9) have a wavelength of 760 to 800 nm, and the ε-type copper, which is currently commonly used in laser beam printers. It can be seen that it has practically flat sensitivity, comparable to that of phthalocyanine. Also Example 31 and Comparative Example 7.9
It has been shown that pigments that do not have the residue represented by general formula (9), such as It is clear that the area will become a trillion sect. In particular, as can be seen by comparing Example 23 and Comparative Example 6 and Example 25 and Comparative Example 8, it is recognized that the electrophotographic photoreceptor of the present invention exhibits higher sensitivity even when similar couplers are used.

Examples 33 to 40 Using the electrophotographic photoreceptors prepared in Examples 1.2.12.15.22.23.24.30, fluctuations in bright area potential and dark area potential during repeated use were measured.

The measurement was carried out by modifying a Canon NP3525 electrophotographic copying machine and attaching the above photoreceptor to its cylinder.

The photoreceptors prepared in Examples 22, 23, 24, and 30 were measured using a modified Canon LBP-Cx printer using a 778 nm semiconductor laser as an exposure optical system.

This installation machine has a structure that allows an image to be obtained on the transfer paper as the cylinder is driven.

Using this installation machine, we set the initial bright area potential (VL) and dark area potential (VD) to around -100V and -600V, respectively, measured the initial vD and vL, and after using it 5,000 times. vD and vL were measured. Show the results.

33 (1) Boo 100 575
12034 (2) Boo 100
580 13535 (12) 8.00
100 585 1403? (22) 6
00 105 575 13539 (24)
Eloo 105 580 135 Comparative Example 12
~13 The potential durability characteristics of the photoreceptors prepared in Comparative Examples 6 and 8 were evaluated in the same manner as in Example 37. Comparative Examples 12 and 13, respectively.

In all evaluations, a 780 nm semiconductor laser was used as the exposure optical system.

12 Comparative Example 8 590 150 430 155
13 Comparative example 8 800 200 830 350
From the above results, it is fully recognized that the photoreceptor of the present invention has good potential stability.

Example 41 On a charge generating layer formed in the same manner as in Example 1, 2,4.7-1linitro-9-fluorenone 5 was added.
g and poly-4,4'-dioxydiphenyl-2,2-propane carbonate (number average molecular weight 300,000) 5g dissolved in 70ml of tetrahydrofuran to prepare a coating solution with a coating weight of 10g/cm2 after drying. It was applied and dried.

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.

vo: +570V El/2: 6.8fLux, sec Example 42 A polyvinyl alcohol film having a thickness of 0.5IL was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

Next, the dispersion of the trisazo pigment used in Example 1 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying would be 0.51 L, and it was dried to generate a charge. formed a layer.

5 g of pyrazoline compound and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid)
A solution obtained by dissolving the above in 70 mJl of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying was 15p, 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 in Examples 1 and 33. Show the results.

vo knee 655V El/2: 4. IKLux, see durability characteristics Initial VD Knee 600V VL Knee 100V After 5,000 sheets durability VD Knee 560V Vt Knee 145V From the above results, the sensitivity is no problem in practical use, and the potential stability during durable use is also good.

Example 43 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 100 hi and dried to form a subbing layer with a thickness of 0.5p.

Next, 5 g of 2,4.7-dolinitro-9-fluorenone
and poly N-vinylcarnoxole (number average molecular weight 30
A charge-transfer complex compound was prepared by dissolving 5 g of 1,000 ml of tetrahydrofuran in 704 m of tetrahydrofuran.

This charge transfer complex compound and 1 g of Exemplary Pigment (7) were added to a solution in which 5 g of polyester (trade name: Pylon, manufactured by Toyobo Co., Ltd.) was dissolved in 70 ml of tetrahydrofuran, and dispersed. This dispersion was applied onto the undercoat layer and dried to form a layer No. 12 to prepare an electrophotographic photoreceptor.

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

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

vo: +600V El/2 near, 2uux, sec Example 44 On the casein layer of the aluminum plate on which the casein layer used in Example 1 was formed, the baking soda transport layer and charge generation layer of Example 1 were sequentially laminated to form a layer. An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except that the structure was different, and the charging characteristics were measured in the same manner as in Example 1. However, the charging polarity was set to 10. Show the results.

vo: +630V El/2: 4.8uux, see Further, durability stability was evaluated in the same manner as in Example 33 except that the charging polarity was set to ten.

Show the results.

Initial VD: +600V Vt: +100V VD after 5,000 sheets durability: +500V VL: +65V [Effects of the Invention] The electrophotographic photoreceptor of the present invention has a specific trisazo pigment in the photosensitive layer. Either or both of the charge carrier generation efficiency and the charge carrier transport efficiency within the layer is improved, resulting in excellent sensitivity and potential stability during long-term use, as well as sensitivity to long wavelengths.

Claims (1)

[Claims] (1) An electrophotographic photoreceptor characterized by containing a trisazo pigment represented by the following general formula in a photosensitive layer. General formula ▲ Numerical formula, chemical formula, table, etc. are available▼ In the formula, R_1 to R_3 represent a hydrogen atom, an alkyl group, or a halogen atom, and A represents a coupler residue having a phenolic hydroxyl group.