JPH04147265A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance the sensitivity of the photosensitive body and to stabilize its potential characteristics at the time of repeated uses by incorporating a specified disazo pigment in a photosensitive layer. CONSTITUTION:This photosensitive body is obtained by forming on a conductive substrate the photosensitive layer containing the disazo pigment represented by formula I in which each of A1 and A2 is a coupler residue with a phenolic OH group, and this pigment can be embodied by substituting as A1 and A2 the groups of formula II at the 4', 3 position, and it is preferred to use the photosensitive layer containing the pigment and comprising at least 2 layers of an electric charge generating layer and charge transfer layer, and hydrazone type compounds can be used for charge transfer materials.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, an electrophotographic photoreceptor containing a disazo pigment having a specific structure, and an electrophotographic device using the photoreceptor. , concerning facsimile.

[Conventional technology]

Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as electrophotographic photoreceptors.

On the other hand, electrophotographic photoreceptors made of organic photoconductive substances include photoconductive polymers typified by poly-N-vinylcarbazole and 2,5-bis(p-diethylaminophenyl)-1,3,4- Those using low-molecular organic photoconductive substances such as oxadiazole, and those that combine such organic photoconductive substances with various dyes and pigments are known.

Electrophotographic photoreceptors using organic photoconductive substances have good film-forming properties and can be produced by coating, so they have the advantage of providing extremely highly productive and inexpensive photoreceptors. Furthermore, it has the advantage that color sensitivity can be freely controlled by selecting the dyes and pigments used, and a wide range of studies have been conducted to date. Particularly recently, a functionally separated photoreceptor has been developed in which a charge generation layer containing an organic photoconductive dye or pigment is laminated with a charge transport layer containing the aforementioned photoconductive polymer or low-molecular organic photoconductive substance. As a result, significant improvements have been made in the sensitivity and durability, which were considered to be shortcomings of conventional organic electrophotographic photoreceptors.

Azo pigments exhibit excellent photoconductivity, and compounds with various properties can be easily obtained by combining amine components and coupler components. Therefore, many compounds have been proposed to date, including JP-A-54-22834, JP-A-58-70232, JP-A-60-1
Publication No. 31539, Japanese Patent Application Laid-open No. 117553/1983,
JP-A-61-51063, JP-A-61-1210
61, JP 61-215556, JP 61-241763, and JP 63-15856.
Publication No. 1 and the like are already publicly known.

[Problem to be solved by the invention]

However, electrophotographic photoreceptors using conventional disazo pigments are not necessarily sufficient in terms of sensitivity and potential stability during repeated use, and only a few materials have been put into practical use. .

It is therefore an object of the present invention to provide new photoconductive materials.

Another object of the present invention is to provide an electrophotographic photoreceptor having practical high sensitivity characteristics and stable potential characteristics during repeated use.

[Means to solve the problem]

The object of the present invention is to provide an electrophotographic photoreceptor comprising a photosensitive layer containing a disazo pigment represented by the following general formula [1] on a conductive support.

It is solved by the general formula (wherein A1.A□ represents coupler residues having the same or different phenolic hydroxyl groups).

In the general formula (1), AI and At represent coupler residues having the same or different phenolic hydroxyl groups, and preferred examples include compounds represented by the general formulas [2] to [7].

X in the general formulas (2), (3), (4), and (5) is a naphthalene ring that is fused with a benzene ring and may have a substituent;
Represents a residue necessary to form a polycyclic aromatic ring or a heterocycle such as an anthracene ring, a carbazole ring, a benzcarbazole ring, and a dibenzofuran ring.

Y in general formula [7] represents a divalent aromatic hydrocarbon group which may have a substitution value or a divalent heterocyclic group containing a nitrogen atom in the ring. Specifically, 0-phenylene, 0-naphthylene, berinaphthylene, 1,2-antrylene, 3.
4-Pyrazolediyl, 2,3pyridinediyl, 4,5
-pyridinediyl, 6-fuindazolediyl, 6,7
- Divalent groups such as chiralediyl are mentioned.

R,,R in general formulas (2), [3], and (4).

represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, an aroyl group, or a heterocyclic group, and R, , R, both bond to a nitrogen atom to form a nitrogen atom within the ring. may form a cyclic amino group contained in R5 in the general formula [5] represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, and R4 in the general formula [6] has a substituent. represents an optional alkyl group, aryl group, aralkyl group, or heterocyclic group.

The alkyl group in the above expression is a group such as methyl, ethyl, propyl, etc., the aralkyl group is a group such as benzyl, phenethyl, etc., the aroyl group is a group such as benzoyl, the aryl group is a group such as phenyl, naphthyl, allylyl, etc.
Examples of the heterocyclic group include pyridyl, thienyl, thiazolyl, carbazolyl, benzimidazolyl, and benzothiazolyl, and examples of the cyclic amino group containing a nitrogen atom in the ring include pyrrole, viroline, pyrrolidine, pyrrolidone, indole, indoline, carbazole, Examples include imidazole, pyrazole, pyrazoline, oxazine, and phenoxazine.

Examples of substituents include alkyl groups such as methyl, ethyl, and propyl; alkoxy groups such as methoxy and ethoxy; halogen atoms such as fluorine, chlorine, and bromine; alkylamino groups such as dimethylamino and diethylamino; phenylcarbamoyl groups; group, a cyano group, and a halomethyl group such as trifluoromethyl.

Z in the general formula [2] represents an oxygen atom or a sulfur atom, and l represents 0 or 1.

In addition, in general formula [1], A, , A are general formula [2] (3)
. It is also suitable as a charge generating material for lasers.

Representative examples of the disazo pigment used in the present invention are listed below, but the disazo pigment used in the present invention is not limited to these.

The disazo bait used in the present invention is produced by tetrazotizing the corresponding diamine by a conventional method and coupling it with a coupler in an aqueous system in the presence of an alkali, or by converting the tetrazonium salt into a fluoroborate salt, zinc chloride double salt, etc. It can be easily synthesized by coupling with a coupler in an organic solvent such as N-dimethylformamide or dimethylsulfoxide in the presence of a base such as sodium acetate, triethylamine, or N-methylmorpholine.

A1 in general formula [1]. When synthesizing a disazo pigment in which Ax is a different coupler, the above-mentioned tetrazonium salt 11aol is first coupled with 1 mole of one coupler, and then 1 mo1 of the other coupler is synthesized, or diamine One of the amino groups of is protected with an acetyl group, etc., this is diazotized, one coupler is coupled, the protecting group is hydrolyzed with hydrochloric acid, etc., this is diazotized again, and the other coupler is coupled. Can be combined by ringing.

Next, a synthesis example of the disazo pigment used in the present invention will be given.

Synthesis example (synthesis of the above-mentioned exemplified disazo drug grade 1) 300-
150 ml of water in 1 beaker 1. Concentrated hydrochloric acid 20 mole 1 (0,
Add 23 mol) and (0,032 sof), cool to 0°C, and add 4.6 g (0,067 moj) of sodium nitrite to 10 ml of water.
A solution dissolved in A was dropped into the solution over 10 minutes while keeping the temperature of the solution below 5°C. After stirring for 15 minutes, carbon filtration was performed, and 10.5 g of sodium borofluoride (0,
A solution prepared by dissolving 096 powder in 90 l of water was stirred, and the precipitated borofluoride salt was collected by filtration, washed with cold water, washed with isopropyl ether, and dried under reduced pressure at room temperature. Yield 14.3g, yield 92%, then 1! N, N- in the beaker
Add 500 ml of dimethylformamide (DMF) and dissolve the following. After cooling the liquid temperature to 5°C, dissolve 9.7 g (0,020 sof) of the borofluoride salt obtained earlier, and then add 5.1 g (0,020 sof) of triethylamine. 0,050 sof) was added dropwise over 5 minutes. After stirring for 2 hours, the precipitated pigment was collected by filtration, washed four times with DMF and three times with water, and then freeze-dried. Yield 17.6 g, yield 97% Elemental analysis calculated value (%) Actual value (%) C70,2870,31 H3,783,76 N 9.28 9.27 The electrophotographic photoreceptor of the present invention has a conductive support. A photosensitive layer containing a disazo pigment represented by the above general formula [1] is provided on the body. The form of the photosensitive layer may be any known form, but a photosensitive layer containing a disazo pigment represented by the general formula [1] is used as a charge generation layer, and a charge transport layer containing a charge transport substance therein. Particularly preferred is a functionally separated type photosensitive layer in which the following layers are laminated.

The charge generation layer can be formed by coating a coating liquid in which the above-mentioned disazu pigment is dispersed together with a binder resin in a suitable solvent on a conductive support by a known method, and the film thickness is, for example, 5 μI. Preferably 0.1-1μ
It is desirable to use a thin film layer of seaweed.

The binder resin used in this case is selected from a wide range of insulating resins or organic photoconductive polymers, including polyvinyl butyral, polyvinylbenzal, polyarylate, polycarbonate, polyester, phenoxy resin, cellulose resin, acrylic resin, urethane resin. , etc., and the amount used is 8% in terms of content in the charge generation layer.
It is 0% by weight or less, preferably 40% by weight or less.

The solvent used is preferably selected from those that dissolve the resin described above but do not dissolve the charge transport layer or undercoat layer, which will be described later. Specifically, ethers such as tetrahydrofuran and 1,4-dioxane; ketones II such as cyclohexanone and methyl ethyl ketone; amides such as N,N-dimethylformamide; esters such as methyl acetate and ethyl acetate; toluene and xylene. , aromatics such as monochlorobenzene; alcohols such as methanol, ethanol, and 2-propatol; and aliphatic halogenated hydrocarbons such as chloroform and methylene chloride.

The charge transport layer is laminated above or below the charge generation layer, and has the function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transport layer is formed by dissolving a charge transport material in a solvent together with a suitable binder resin if necessary and coating the layer, and the thickness thereof is generally 5 to 40 .mu.m, preferably 15 to 30 .mu.m.

Charge transport substances include electron transport substances and hole transport substances, and examples of electron transport substances include 2,4,7-trinitrofluorenone, 2,4,5,7-titranitrofluorenone, chloranil, and tetracyanoquinodimethane. Examples include electron-withdrawing substances such as , and polymerization of these electron-withdrawing substances.

Examples of hole transport substances include polycyclic aromatic compounds such as pyrene and anthracene; carbazole, indole, imidazole, oxazole, thiazole, oxadiazole,
Heterocyclic compounds such as pyrazole, pyrazoline, thiadiazole, triazole; hydrazone compounds such as p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole; α-phenyl -4'
-N,N-diphenylaminostilbene, 5- (4
Styryl compounds such as -(dip-)lylamino)benzylidene]-5H-dibenzo(a,d)cycloheptene; benzidine compounds; triarylmethane compounds;
Polymers having triphenylamine or a group consisting of these compounds in the main chain or side chain (e.g. poly-N
-vinylcarbazole, polyvinylanthracene, etc.)
can be mentioned.

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, an appropriate binder resin can be used, and specifically, acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, polysulfone, polyacrylamide, Examples include insulating resins such as polyamide and chlorinated rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

Examples of the conductive support on which the photosensitive layer is formed include aluminum, aluminum alloy, copper, zinc, stainless steel,
Titanium, nickel, indium, gold, platinum, etc. can be used. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, boreethylene terephthalate, acrylic resin, etc.) and conductive particles (e.g., carbon black, silver particles, etc.) are coated with these metals or alloys by vacuum deposition. A material coated on a plastic or metal substrate with a binder, or a material obtained by impregnating conductive particles into plastic or paper can be used.

An undercoat layer having barrier and adhesive functions can also be provided between the conductive support and the photosensitive layer.

The thickness of the undercoat layer is 5 μm or less, preferably 0.1 to 3 μm.
- is appropriate. The undercoat layer is casein, polyvinyl alcohol, nitrocellulose, polyamide (nylon 6,
Nylon 66, nylon 610, copolymerized nylon, N-
(alkoxymethylated nylon, etc.), polyurethane, aluminum oxide, etc.

Another specific example of the present invention is an electrophotographic photoreceptor containing the above-mentioned disazo pigment and charge transport material in the same layer. At this time, a charge transfer complex consisting of poly-N-vinylcarbazole and trinitrofluorenone can also be used as the charge transport substance.

The electrophotographic photoreceptor of this example can be formed by coating and drying a solution in which the above-mentioned disazo pigment and charge transporting substance are dispersed in a suitable resin solution.

General formula used in any electrophotographic photoreceptor [
The crystal form of the disazo pigment represented by the formula [1] may be crystalline or amorphous, and if necessary, the crystal form of the disazo pigment represented by the general formula [1] may be crystalline or amorphous.
] It is also possible to use a combination of two or more kinds of disazo pigments shown in the following, or to use them in combination with a known charge-generating substance.

FIG. 1 shows a schematic configuration example of a general transfer type electrophotographic apparatus using the electrophotographic photoreceptor of the present invention.

In the figure, reference numeral 1 denotes a drum-type photoreceptor of the present invention as an image carrier, which is rotated at a predetermined circumferential speed in the direction of the arrow around an axis 1a. The photoreceptor 1 is charged by charging means 2 during its rotation process.
The peripheral surface is uniformly charged with a predetermined positive or negative potential, and then exposed to light image L (slit exposure, laser beam scanning exposure, etc.) by an image exposure means (not shown) in the exposure section 3.
receive. As a result, electrostatic latent images corresponding to the exposed images are sequentially formed on the circumferential surface of the photoreceptor.

The electrostatic latent image is then developed with toner by the developing means 4, and the toner developed image is transferred by the transfer means 5 from a paper feed section (not shown) between the photoreceptor l and the transfer means 5 in synchronization with the rotation of the photoreceptor l. The images are sequentially transferred onto the surface of the transfer material P that is fed.

The transfer material P that has undergone the image transfer is separated from the photoreceptor surface and introduced into the image fixing means 8, where the image is fixed and a copy is produced.
will be printed out on the outside of the aircraft.

After the image has been transferred, the surface of the photoreceptor 1 is cleaned by a cleaning means 6 to remove residual toner, and is further subjected to a charge removal process by a pre-exposure means 7, and is used repeatedly for image formation.

As the uniform charging means 2 for the photoreceptor 1, a corona charging device is generally widely used. Further, for the transfer device 5, corona transfer means is generally widely used.

An electrophotographic apparatus is constructed by combining a plurality of components such as the above-mentioned photoreceptor, developing means, and cleaning means into an apparatus unit, and this unit is configured to be detachable from the apparatus main body. For example, the photoreceptor 1 and the cleaning means 6 may be integrated into one apparatus unit, and may be configured to be detachable using a guide means such as a rail of the apparatus main body. At this time, the above-mentioned device unit may include a charging means and/or a developing means.

When using an electrophotographic device as a copying machine or printer, light image exposure involves scanning the reflected light or transmitted light from the original, or reading the original into a signal, and using this signal to scan the laser beam and drive the LED array. , or by driving a liquid crystal shutter array.

When used as a facsimile printer, the optical image exposure is exposure for printing received data. FIG. 2 is a block diagram showing an example of this case.

The controller 11 controls the image reading section 10 and the printer 19. The entire controller 11 is controlled by a CPU 17. The read data from the image reading unit 10 is
The signal is transmitted to the other station through the transmission circuit 13. Data received from the partner station is sent to the printer 19 through the receiving circuit 12. Predetermined image data is stored in the image memory 16.

A printer controller 18 controls a printer 19. 14 is a telephone.

Image information received from the line 15 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 12, decoded by the CPU 17, and sequentially stored in the image memory 16. .

Then, when at least one page of image information is stored in the memory 16, the CPU performs image recording of that page.
17 reads one page of image information from the memory 16 and sends the decoded one page of image information to the printer controller 18 .

When the printer controller 18 receives one page of image information from the CPUI 7, it controls the printer 19 to record the image information of that page.

Note that the CPU 17 is receiving the next page while the printer 19 is recording.

Images are received and recorded using the keyaki described above.

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

〔Example〕

The present invention will be explained below using examples.

5 g of methoxymethylated nylon resin (average molecular weight: 45,000) and 10 g of alcohol-soluble copolymerized nylon resin (average molecular weight: 65,000) were placed on the upper aluminum substrate of the back panel.
was dissolved in 95 g of methanol and coated with a Mayer bar to form an undercoat layer having a thickness of 1 μm after drying.

Next, 25 g of the above-exemplified disazo pigment was added to a solution prepared by melting 2 g of butyral resin (butyralization degree: 65 mol %) in 95 g of cyclohexanone, and dispersed in a sand mill for 10 hours. This dispersion was applied onto the previously formed undercoat layer using a Mayer bar to form a charge generation layer so that the film thickness after drying was 0.18 μm.

Next, 5 g of a hydrazone compound represented by the following structural formula and a polymethyl methacrylate resin (number average molecular weight 8000
0) Dissolve 5 g in 80 g of monochlorobenzene,
Apply this on the charge generation layer with a Mayer bar and dry.
A charge transport layer of 16 μm was formed to produce a photoreceptor of Example 1.

Photoreceptors corresponding to Examples 2 to 15 were similarly prepared using other exemplary pigments shown in Table 1 in place of disazo pigment Grade 2.

The electrophotographic photoreceptor thus prepared was negatively charged with a -5kV corona discharge using an electrostatic copying paper tester (Model 5P-428) manufactured by Kawaguchi Electric, and after being left in the dark for 1 second, a halogen lamp was turned on. The charging characteristics were evaluated by exposing to light with an illuminance of 1 flux. As for charging characteristics, surface potential ■. Then, the exposure amount E1/2 required for the surface potential to attenuate to 172 after being left in a dark place was measured. The results are shown in Table 1.

Table 1 Kono J! [1el] Exactly the same electrophotographic photoreceptor was prepared, except that the disazo pigment used in Example 1 was replaced with a disazo pigment represented by the following structural formula, and the charging characteristics were evaluated in the same manner. The results are shown in Table 2.

From these results, it can be seen that the electrophotographic photoreceptors of the present invention all have sufficient charging ability and excellent sensitivity.

The electrophotographic photoreceptor prepared in Example 1 was equipped with a -6.5 kV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner. It was attached to the cylinder of an electrophotographic copying machine.

The initial dark potential V0 and light potential ■1 are each -700
V, was set at around -200V, and the amount of variation in dark area potential (ΔV,) and the amount of variation in light area potential (ΔVL) when used repeatedly 5000 times were measured.

The photoreceptors prepared in Examples 2 to 15 were similarly evaluated, and the results are shown in Table 3.

Note that a negative sign in the amount of potential variation represents a decrease in the absolute value of the potential, and a positive sign represents an increase in the absolute value of the potential.

The amount of potential fluctuation during repeated use of the photoreceptors prepared in Comparative Examples 1 to 3 was measured in the same manner as in Example 16. The results are shown in Table 4.

Table 4 From Examples 16 to 30 and Comparative Examples 4 to 6, it can be seen that the electrophotographic photoreceptor of the present invention has little potential fluctuation during repeated use.

Actual Difference 11 A subbing layer of polyvinyl alcohol having a thickness of 0.5 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. On top of this, the dispersion of the disazo pigment used in Example 3 was applied with a Mayer bar and dried, resulting in a film thickness of 0.2
A μ-charge generation layer was formed.

Next, a styryl compound Log shown by the following structural formula and a polycarbonate resin (number average molecular weight 65,000) 8
g dissolved in 70 g of tetrahydrofuran was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 17 μm. The charging characteristics and durability characteristics of the photoreceptor thus prepared were measured in the same manner as in Examples 1 and 16. The results are shown below.

Vo: 700 (-V) E 1/2: 0
．． 85 (lux, 5ec) △V,: +3m ΔVL
:1(V) Husband's home owner I A photoreceptor was prepared by applying the charge generation layer and charge transport layer of the photoreceptor prepared in Example 13 in the reverse order, and the charging characteristics were evaluated in the same manner as in Example 1. did. However, the charging was set to positive It.

Vo: 697 (-V) E 1/2: 1
．． 07 (Iux, 5ec), lll Host On the charge generation layer prepared in Example 15, 5 g of 2.4.7 trinitro-9-fluorenone and poly-4,4'dioxydiphenyl-22'-propane carbonate (molecular weight 300,000 ) 5 g dissolved in 50 g of tetrahydrofuran was coated with a Mayer bar and dried to a film thickness of 8 months.
A μ-charge transport layer was formed.

The charging characteristics of the electrophotographic photoreceptor thus prepared were evaluated in the same manner as in Example 1. However, the charging was positive.

Vo: 697 (+V) E 1/2: i
, 5 (lux, 5ec) Hutamanuki ↓ 60.5 g of the above-mentioned disazo pigment was dispersed in a paint shaker for 5 hours together with 9.5 g of cyclohexanone. A solution prepared by dissolving 5 g of the charge transport material used in Example 1 and 5 g of polycarbonate resin in 40 g of tetrahydrofuran was added to the mixture, and the mixture was further shaken for 1 hour. The coating solution thus prepared was applied onto an aluminum substrate using a Mayer bar and dried to form a photosensitive layer having a thickness of 15 μm.

The electrophotographic photoreceptor thus produced was evaluated for charging characteristics in the same manner as in Example 1. However, the charging was positive.

Vo: 698 (+V) E 1/2: 5
．． 3 (lux, 5ec) [Effects of the Invention] As described above, the electrophotographic photoreceptor of the present invention uses a disazo pigment having a specific structure in the photosensitive layer, thereby improving the generation efficiency or injection of charge carriers inside the photosensitive layer. Either or both of the efficiencies are improved, and characteristics excellent in sensitivity and potential stability during repeated use can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a general transfer type electrophotographic apparatus. FIG. 2 is a block diagram of a facsimile machine using an electrophotographic device as a printer. : Photoreceptor, : Exposure section, : Transfer means, : Pre-exposure means, 2: Charging means, 4: Developing means, 6: Cleaning means, 8: Image fixing means.

Claims (4)

[Claims] (1) An electrophotographic photoreceptor characterized by having a photosensitive layer containing a disazo pigment represented by the following general formula [1] on a conductive support. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ 1] (wherein A_1 and A_2 represent coupler residues having the same or different phenolic hydroxyl groups). (2) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer comprises at least two layers: a charge generation layer containing a disazo pigment represented by the general formula [1], and a charge transport layer. (3) An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim (1). (4) A facsimile machine comprising the electrophotographic photoreceptor according to claim (1) and receiving means for receiving image information from a remote terminal.