JPH02146552A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic sensitive body having excellent sensitivity and potential stability in durable use by using a specific disazo pigment in a photosensitive layer. CONSTITUTION:The disazo pigment expressed by the formula I is incorporated into the photosensitive layer. In the formula I, R1 denotes a hydrogen atom, alkyl group, aryl group, aralkyl group, heterocyclic group which may have a substituent or halogen group; R2, R3 denote a hydrogen atom, alkyl group, aryl group, aralkyl group, heterocyclic group which may have a substituent or halogen group; A denotes a residual coupler group having a phenolic hydroxyl group. The electrophotographic sensitive body which has the practicable high sensitivity characteristic in a visible light region and has the stable potential characteristic at the time of repetitive use and is improved in a photomemory characteristic is obtd.

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 disazo pigment having a specific molecular structure in a photosensitive layer.

[Prior Art] Electrophotography, as disclosed in U.S. Pat. No. 2,297,691, involves coating an insulating material in the dark, the electrical resistance of which changes depending on the amount of radiation received during image exposure. A photoconductive material consisting of a support is used.

The basic characteristics required of an electrophotographic photoreceptor using this photoconductive material are (1) ability to be charged to an appropriate potential in a dark place, (2) low charge dissipation in a dark place, ( 3) The ability to quickly dissipate charges by light irradiation.

Conventionally, electrophotographic photoreceptors have been made of selenium, zinc oxide, a
Inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive compound such as cadmium chloride have been widely used. However, although these satisfy the conditions (1) to (3) above,
It is not always satisfactory in terms of thermal stability, #humidity, durability, etc.0 For example, when selenium crystallizes, its properties as a photoreceptor deteriorate, making it difficult to manufacture and also susceptible to heat and fingerprints. It crystallizes and its performance as a photoreceptor deteriorates. In addition, cadmium sulfide has problems with moisture resistance and durability, and zinc oxide has problems with smoothness, hardness, and abrasion resistance.

Furthermore, most inorganic photoreceptors have a limited photosensitive wavelength range. For example, selenium has a sensitive wavelength range in the blue range and has almost no sensitivity in the red range.

For this reason, various methods have been proposed to extend photosensitivity to longer wavelength ranges, but there are many restrictions on the selection of photosensitive wavelength ranges.Even when zinc oxide or cadmium sulfide is used as a photoreceptor, the photosensitive wavelength range of the photoreceptor itself is limited. is narrow and requires the addition of various sensitizers.

In order to overcome these drawbacks of inorganic photoreceptors, electrophotographic photoreceptors containing various organic photoconductive compounds as main components have been actively developed in recent years.

For example, Japanese Patent Publication No. 50-10496, U.S. Patent No. 34
No. 84237 Mei@1 describes a photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2.4.7-) dinitrofluorenone-9-one, and a photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole with a biryllium salt dye. There are sensitized ones (Japanese Patent Publication No. 48-25858).

Although these organic electrophotographic photoreceptors have improved the drawbacks of the inorganic electrophotographic photoreceptors to some extent, they generally have low photosensitivity and are not suitable for repeated use. In order to overcome these drawbacks, various photoreceptors have been proposed as organic electrophotographic photoreceptors in recent years. , a charge generation layer), and a substance that accepts and transports the charge carriers generated by the charge generation layer (
Compared to conventional organic electrophotographic photoreceptors, the laminated photoreceptor is composed of a layer mainly containing a charge transport material (hereinafter referred to as a charge transport layer), and has a higher sensitivity to the shell than conventional organic electrophotographic photoreceptors. Some of them have been put into practical use due to their ability to improve performance.

Such organic photoconductive compounds are easier to synthesize than inorganic photoconductive compounds, and the visible light sensitivity can be changed relatively easily by molecular design, making it easy to control color sensitivity. In recent years, various companies have been competing with each other to develop semiconductors, as they are non-polluting, highly productive, and economically efficient compared to inorganic semiconductors.
There are quite a few products that have reached the level of practical use, such as durability.

However, at present, it is still inferior to inorganic photoconductive compounds such as amorphous silicon in terms of durability, especially the stability of potential after repeated use, and the presence or absence of potential changes due to environmental changes. do not have.

In addition, it also exhibits sufficient characteristics for the so-called photomemory property, which is a phenomenon in which when an electrophotographic photoreceptor is left open in a place where a certain amount of light is emitted, the potential of the part that is hit by that light is attenuated. It wasn't something.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel electrophotographic photoreceptor, which has practical high sensitivity in the visible light range.4. To provide an electrophotographic photoreceptor that has stable potential characteristics and improved photomemory characteristics when used with ν properties;
An object of the present invention is to provide novel photoconductive compounds.

c. Means and Effects for Solving the Problems] The present invention comprises an electrophotographic photoreceptor characterized in that a photosensitive layer contains a disazo pigment represented by the following general formula (1).

In the general formula, R1 represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, a heterocyclic group, or a halogen group, and R2 and R3 represent a hydrogen atom or an alkyl group that may have a substituent. It represents a suitable alkyl group, aryl group, aralkyl group, heterocyclic group or halogen group, and A represents a coupler residue having a phenolic hydroxyl group.

More specifically, groups other than hydrogen atoms represented by R1, R2, and R3 include groups such as methyl, ethyl, propyl, isopropyl, butylene groups, halogen groups, cyano groups, etc. as non-stirrup substituted alkyl groups. - Groups such as HC3C1 -CHF-CH2F as substituted alkyl groups, groups such as benzyl, 7enethyl, and naphthylmethyl as aralkyl groups, groups such as phenyl, naphthyl, and anthryl as aryl groups, and benzene rings of aryl groups. Halogen group in part,
Groups substituted with alkyl groups such as methyl and ethyl, substituted alkyl groups such as chloromethyl, groups such as pyridine, thienyl, furyl, and carbazolyl as heterocyclic groups, and groups in which one or more hydrogen atoms of the heterocyclic group are halogen group,
Examples of the group substituted with a substituted or #i-substituted alkyl group and the halogen group include groups such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

More preferred specific examples of the coupler residue having a phenolic hydroxyl group represented by A include the following formulas (2) to (8):
Examples include the residues shown below.

,Y, The ring represents a residue necessary to form an aromatic ring or a heterocycle, and may have a substituent.

R4 and R5 represent a hydrogen atom, an alkyl group which may have a substituent, an aryl, an aralkyl Ti, a heterocyclic group, or a cyclic amino group containing in the ring a nitrogen atom to which R4 and R5 are bonded.

Specific examples of alkyl groups include methyl, ethyl, propyl, and butyl; specific examples of aralkyl groups include benzyl, phenethyl, and naphthylmethyl; specific examples of aryl groups include phenyl, diphenyl, naphthyl, anthryl, and aim groups. Specific examples include carbazole and dibenzo dirane.

benzimidacilone, benzthiazole, thiazole,
Examples include pyridine.

R6 represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group or an aralkyl group.

A specific example of R6 is shown by the same example as R4 and R5 described above.

Substituents in the alkyl group, aryl group, aralkyl group, alkoxy group, and heterocyclic group represented by the substituents R4 to R, and 3 in general formulas (2) to (4) include, for example, a fluorine atom, a chlorine atom, and an iodine atom. , halogen atoms such as bromine atoms, alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, methoxy, ethoxy, propoxy,
Alkoxy groups such as phenoxy, nitro groups, cyano groups,
Examples include substituted amine groups such as dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring; examples of the divalent aromatic hydrocarbon group include monocyclic aromatic carbide such as 0-phenylene; Divalent groups of hydrogen, divalent groups of condensed polycyclic aromatic hydrocarbons such as 0-naphthyleneperinaphthylene, 1,2-antrylene, 9゜10-phenanthrylene, etc. Examples of the heterocyclic divalent group include 3.4-pyrazolediyl group, 2,3-pyridinediyl group, 14°5-pyrimidinediyl group, 6.7-indazolediyl group, 6.
Divalent groups such as 7-chiralindiyl group can be mentioned.

In the formula, R7 represents an aryl group or a heterocyclic group which may have a substituent; specifically, the aryl group is phenyl, naphthyl, anthryl, pyrenyl, and the heterocyclic group is pyridyl, thienyl, furyl, carbazolyl. Indicates the group.

Furthermore, substituents for aryl groups and heterocyclic groups include halogen atoms such as fluorine, chlorine, iodine, and bromine, alkyl groups such as methyl, ethyl, propylisopropyl, and butyl, and methoxy, ethoxy, propoxy, and phenoxy. Alkoxy group, nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino,
Examples include substituted amine 7 groups such as morpholino, piperidino, and pyrrolidino.

R8 and R9 represent an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent; specifically, the alkyl group is methylethyl, propyl, butyl, and the aralkyl group is benzyl, phenethyl. , naphthylmethyl, aryl groups include phenyl, diphenyl, naphthyl, anthryl, heterocyclic groups include carbazolylthienyl, pyridyl, furyl, etc. Substitution of alkyl groups, aralkyl groups, aryl groups, and heterocyclic groups Examples of groups include halogen atoms such as fluorine, chlorine, iodine, and bromine atoms; alkyl groups such as methyl, ethyl, propyl, and isopropyl; butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy; nitro groups; and cyano groups. , dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino and other substituted amino groups.

Specific examples of the disazo pigment represented by the general formula (1) are listed below.

As a method of description, A, which is a coupler residue having a central skeleton of a disazo pigment and a phenolic hydroxyl group, is described.

Exemplified Pigment (1) Exemplified Pigment (3) Central Skeleton 2 Same as Above Exemplified Pigment (4) Central Skeleton 2 Same as Above Exemplified Pigment (2) Exemplified Pigment (5) Central Skeleton, Same as Above Central Skeleton: Same as Above Exemplified Pigment Central Skeleton: Same as Above Exemplified Pigment Center Skeleton - Central skeleton of the above-mentioned exemplary pigment: Same as above-mentioned exemplary pigment (12) Central skeleton: Same as above-mentioned exemplary pigment (13) Central skeleton: Same as above-mentioned exemplary pigment (14) Central skeleton; Same as above-mentioned exemplary pigment (15) Exemplary pigment central skeleton: Same as above-mentioned exemplary pigment (l O) Central skeleton: Same as above Exemplary pigment (11) Central skeleton: Same as above Central skeleton: Same as above N Exemplary pigment (1) Central skeleton: Same as above Exemplary pigment (17) Central skeleton: Same as above Exemplary pigment (18) Central skeleton: Exemplified pigment (19) as above Central skeleton: Exemplified pigment (20) as above Central skeleton: Exemplified pigment (25) as above Central skeleton: Exemplified pigment as above (26) Central skeleton: Exemplified pigment as above (27) Central skeleton: Exemplified Pigment (28) Same as above Central skeleton: Same as above C-cross exemplary pigment (22) Central skeleton: Exemplary #4 (23) Same as above Central skeleton: Exemplified pigment (24) Same as above Central skeleton: Exemplary pigment (29) Same as above Central skeleton: Same as above Exemplary Pigment (30) Central Skeleton #5: Same as above Exemplary Pigment (31) Central Skeleton Exemplary Pigment (32) Same as above Central Skeleton: Same as above Exemplary Pigment (33) Central skeleton: Same as above O Exemplary Pigment Central Skeleton 2 Same as above n Exemplary Pigment (35) Central skeleton: Same as above Exemplified pigment (39) Central skeleton: Same as above H Exemplified pigment (40) Central skeleton: Same as above Exemplified pigment (41) Exemplified pigment (36) Central skeleton: Same as above H3 H Exemplified pigment (37) Central skeleton: Same as above H Exemplified pigment (38) Central skeleton: Exemplified pigments as above (42) Central skeleton: Exemplified pigments as above (43) Central skeleton: Exemplified pigments as above (44) Central skeleton: Exemplified pigments as above (45) Central skeleton: Exemplified pigments as above (49) Exemplary pigment (46) Exemplary pigment (50) Exemplary pigment (47) Central skeleton: Exemplary pigment (48) Same as above Exemplary pigment (51) Exemplary pigment (55) Central skeleton: Same as above Exemplary pigment (52) Exemplary pigment (56) Central skeleton : Same as above A: 0IIH CH H I2 k Exemplary M material (53) Central skeleton 2 Same as above H A : COW) I Exemplary pigment (57) Central skeleton: Same as above Exemplary pigment (54) Central skeleton: Same as above O 0NI-1 Exemplary pigment + (S8) Central Skeleton Exemplified Pigment Same as Above (60) Central Skeleton: Exemplified Pigment Same as Above (61) C to H Te C Tech H5 Exemplified Pigment (65) Exemplified Pigment (66) Exemplified Pigment (67) Central Skeleton Exemplified Pigment Same as Above (62) Central skeleton: Same as above Exemplary face $4 (63) Exemplary pigment (64) Central skeleton: Same as above Exemplary pigment (68) Exemplary pigment (69) Central skeleton: Same as above Exemplary pigment (70) Exemplary pigment (71) Exemplary pigment (72) Center Skeleton: Exemplified Pigment Same as Above (73) Central Skeleton II Exemplified Pigment (78) H2F / Exemplified Pigment (79) Central Skeleton: Exemplified Pigment Same as Above (80) Central Skeleton: Exemplified Pigment Same as Above (74) Central Skeleton: Exemplified Pigment Same as Above (75) ) Central skeleton: Same as above Exemplary pigment (76) Exemplary face $4 (77) Exemplary pigment ( Exemplary pigment (82) Central skeleton: Same as above Exemplary face #4 (83) Central skeleton: Same as above Exemplary pigment (84) Central skeleton: Same as above example Pigment (85) Central skeleton: Same as above Exemplified pigment (86) Central skeleton: Same as above (Also exemplary face N (90) Central skeleton: Same as above Exemplary pigment (91) Central skeleton: Same as above Exemplary pigment (92) Central skeleton: Same as above Exemplary pigment ( 87) Central skeleton: Same as above Exemplified pigment (88) Central skeleton: Same as above Exemplified pigment (89) Central skeleton: Same as above Exemplified pigment (93) Central skeleton: Same as above Exemplified R material Central skeleton: Same as above Exemplified pigment (95) Central skeleton: Same as above Exemplified Pigment (96) Central Skeleton: Exemplified Pigment (97) Central Skeleton: Exemplified Pigment (98) Central Skeleton: Exemplified Pigment (98) Central Skeleton: Exemplified Pigment (1) : Exemplified Pigment Same as Above (99) Central Skeleton Exemplified Pigment Same as Above (1) Central Skeleton: Exemplified Pigment Same as Above (1 Of) Central Skeleton: Exemplified Pigment Same as Above (1) Central skeleton: Exemplified pigment as above (1 Central skeleton: Exemplified pigment as above (1) Central skeleton: Exemplified pigment as above (1) Central skeleton: Exemplified pigment as above (1 Central skeleton: Exemplified pigment as above (1 Central skeleton: Exemplified pigment as above) Exemplary pigment (1 Central skeleton: Same as above H Exemplary pigment (1 Central skeleton: Same as above) Exemplary pigment (1 Central skeleton: Same as above) Same as above H Exemplary pigment (1 Central skeleton: Same as above b) The disazo pigment of the general formula (1) used in the present invention is, for example, treated with nitrous acid to tetrazotize the amine represented by the following structural formula (■), and then - a formula (2) to (8
) is subjected to aqueous coupling in the presence of an alkali, or the tetrazonium salt of the amine is once isolated in the form of a borofluoride salt or zinc chloride double salt, and then a suitable solvent, For example, N, N-
It can be produced by coupling with the above coupler in a solvent such as dimethylformamide or dimethyl sulfoxide in the presence of an alkali.

Synthesis Example (Synthesis of Exemplary Pigment (21)) Water in a 500m beaker at 80°C, concentrated hydrochloric acid 16.6mJ
l (0.19 mol) and while cooling in an ice water bath,
6.475 g of amine represented by the above structural formula (0,02
9 mol) was added thereto, and the liquid temperature was brought to -2°C while stirring.

Next, add 6.3 g (0,0915 mol) of sodium nitrite to 1 mol of water.
A solution dissolved at 0 mM was added dropwise over 20 minutes while controlling the liquid temperature to 2° C. or lower, and after the addition was completed, the solution was stirred at the same temperature for an additional 15 minutes.

Carbon was added to the reaction solution and filtered to obtain a tetrazotized solution.

Next, add 700 m of dimethylformamide to a 2 fL beaker.
19.9 g (0.20 mol) of triethylamine was added, and 27.24 g (0.0915 mol) of 2-hydroxy-3-naphthoic acid-2"-chloroanilide was added and dissolved.

Cool this coupler solution to 10°C and bring the liquid temperature to 5-10°C.
The above-mentioned tetrazotized solution was added dropwise with stirring over 30 minutes while controlling the temperature, and then stirred at room temperature for 2 hours. The reaction solution was filtered, washed with water, and filtered to give a crude pigment of 39.9% in terms of solid content.
5g of water paste was obtained.

Next, using 400 ml of N,N-dimethylformamide, the mixture was filtered with stirring at room temperature and turned over four times.

Then, each was treated with 400 mM methyl ethyl ketone
After repeating stirring and filtration, dry explosion was carried out under reduced pressure at room temperature to obtain 18.8 g of purified pigment.

Yield 80%, decomposition point 250℃ or above Elemental analysis Calculated value (%) Experimental value (%) C74,
474,I H3,83°6 N 9.0 8.2 Although the method for synthesizing one typical pigment has been described above, other disazo pigments can be synthesized in a similar manner.

The electrophotographic photoreceptor of the present invention has a conductive support of the general formula (
It has a photosensitive layer containing the disazo pigment shown in 1). The form of the photosensitive layer may be any known form, but - a photosensitive layer containing a disazo pigment represented by formula (1) is used as a charge generation layer, and a charge transport layer containing a charge transport substance is added thereto. Laminated functionally separated photosensitive layers are particularly preferred.

The charge generation layer can be formed by coating a coating solution in which the disazo pigment described above is dispersed together with a binder resin in a suitable solvent on a conductive support by a known method, and the film thickness thereof is, for example, 5 pm. Below, preferably 0
．． A thin film layer of 1 to lpm is desirable.

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, polyurethane. etc., and the amount used is preferably 80% in terms of content in the charge generation layer.
It is not more than 40% by weight, preferably not more than 40% by weight.

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 described later.

Specifically, ethers such as tetrahydrofuran and 1,4-dioxane, ketones such as cyclohexanone methyl ethyl ketone, amides such as N,N-dimethylformamide, esters such as methyl acetate and ethyl acetate, toluene, xylene, and chlorobenzene. Examples include aromatics such as methanol, ethanol, alcohols such as 2-propanol, and aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichlorethylene.

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 substance in a solvent together with an appropriate binder resin as necessary and coating the layer, and the film thickness is generally 5 to 40 μm, but 1
5 to 30 gm is preferred.

Charge transport substances include electron transport substances and hole transport substances. Examples of electron transport substances include 2°4.7-1linitrofluorenone, 2,4,5°7-titranitrofluorenone, chloranil, Examples include electron-withdrawing substances such as tetracyanoquinodimethane and polymerized materials of these electron-withdrawing substances.

Hole-transporting substances include polycyclic aromatic compounds such as pyrene and anthracene, carbazole-based, indole-based, imidazole-based, oxazole-based 1 thiazole-based, oxadiazole-based, pyrazole-based, pyrazoline-based, thiadiazole-based, and triazole-based compounds. Heterocyclic compounds such as
p-diethylaminobenzaldehyde-N,N-diphenylhydrazone, N,N-diphenylhydrazino-3-
Hydrazone compounds such as methylidene-9-ethylcarbazole, α-phenyl-4′-N,N-diphenylaminostilbene, 5-[4-(di-p-tolylamino)benzylidene]-5H-dibenzo[a, d]
A polymer having a styryl compound such as cycloheptene, a benzidine compound, a triarylmethane compound, triphenylamine, or a group consisting of these compounds in its main chain or side chain (for example, poly-N-vinylcarbazole).

polyvinylanthracene, etc.).

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 suitable binder can be used. Specifically, insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, polyacrylamide, polyamide, and chlorinated rubber, or organic photoconductive resins such as poly-N-vinylcarbazole and polyvinylanthracene. Polymers and the like can be mentioned.

Examples of the conductive support on which the photosensitive layer is formed include aluminum, aluminum alloy, copper, zinc stainless steel, vanadium, molybdenum, chromium titanium, nickel, indium, gold, and platinum. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, etc.) in which such metals or alloys are coated by vacuum deposition, or conductive particles (e.g., carbon black, silver particles, etc.) are coated with a suitable binder resin. In addition, a support coated on a plastic or metal substrate, or a support made of plastic or paper impregnated with conductive particles can be used.

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

The subbing layer can be formed of casein, polyvinyl alcohol, nitrocellulose, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, aluminum oxide, or the like.

The thickness of the subbing layer is 5 g, m or less, preferably 0.1 to 3 I
Lm is appropriate.

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, poly-N-
Charge transfer complexes consisting of vinylcarbashield trinitrofluorenone can also be used.

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

The pigment used in any electrophotographic photoreceptor is a combination of two or more types of disazo pigments represented by formula (1),
It is also possible to use it in combination with known charge generating substances.

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

[Example] Examples 1 to 27 Ammonia aqueous solution of casein (casein 1
1.2% ammonia water, 1 g of ammonia water, 222 ml of water) was applied using a Mayer bar so that the film thickness after drying was 1.0 pm, and dried.

Next, 5 g of the above-mentioned exemplary pigment (21) was added to a pot prepared by dissolving 2 g of butyral resin (degree of butyralization: 63 mol %) in 95 mJl of cyclohexanone, 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 was 0.5 pm, and dried to form a charge generation layer.

Next, 5 g of a hydrazone compound with the following structural formula, 5 g of a hydrazone compound, and polycarbonate (number average molecular weight 40,000)
5 g of chlorobenzene was dissolved in 80 ml of chlorobenzene, and this solution was applied onto the charge generation layer using a Mayer bar so that the film thickness after drying would be 291 Lm, and dried to form a charge transport layer. created a body.

Examples 2 to 27 using the following exemplified pigment in place of exemplified pigment (21) for the azo pigment, and using the same conditions as in Example 1 except for the following exemplified pigment.
An electrophotographic photoreceptor corresponding to the above was created.

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Kawaguchi Denki M Od 8 sentence EPA-810).
0) in a static manner at 15 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
/2) was measured.

Furthermore, the same measurement is performed 150 times in a row, the 150th VQ is measured, and the value of the difference from the initial Vo [Vo (initial) - v, ) (tso time)] is calculated as the falling value ΔVo
It was measured as

Furthermore, the surface potential (
After measuring Vo ), the photoreceptor was left under a daylight type fluorescent lamp for 3 minutes.

The amount of light at this time was 1,000 lux.

Next, leave it in the dark for 3 minutes, and use the same measurement method as before.
Vo was measured, and 0 after exposure to light was taken as vo 2, and the change in chargeability, VO-Vo2, was used as a photo memory.

The measurement results will be described later.

Comparative Examples 1 to 5 Electrophotographic photoreceptors were prepared in the same manner as in Example 1, except that an azo pigment having the following structural formula was used, and the characteristics were measured in the same manner as in Example 1.

Show the results.

(Comparative example 1) Comparative pigment (described in JP-A-57-195767) (Comparative example 2) Comparative pigment (described in JP-A-61-272754) (Comparative example 3) Comparative pigment (described in JP-A-61-43662) (Comparative example 4) Comparative pigment (Example 6 described in JP-A-58-16775967759) Comparative pigment (Described in JP-A-61-151547) (Comparative example 5
) Comparative pigment (described in JP-A-55-69148) (Comparative Example 7) Comparative pigment (described in JP-A-61-107250) 1.5 1.4 1.8 2.1 1.7 1.8 2.1 2 , 4 1.3 1 , 4 1.9 2.6 1.7 2.1 2.2 (10B) (t t 1) v-■ 2 , 3 1 , 3 1.6 1 , 8 1.5 1.3 1 , 4 1.5 1 , 8 1.9 2.1 2.2 E l/2 lux 5ec 2.0 5 , 8 6 , 81 1.6 6 , 2 2.9 4. 0 Δvv 〇〇 = 5 + 5 〇 = l O Tomemory - ■ 〇〇〇〇〇 Δvv +20 +15 +15 Foot memory - It has sufficient sensitivity to suppress potential fluctuations (
It can be seen that ΔVo) and photo memory are also small.

For example, Comparative Example 2.4 and Example 13.14.16.21 are examples in which the coupler components are the same but the central skeleton is changed.
In this case, as is clear from comparing Comparative Example 1 and Example 9.19, the electrophotographic photoreceptor of the present invention is often superior in sensitivity to the electrophotographic photoreceptor of the comparative example. , and even with the same sensitivity, there is less potential fluctuation and less photomemory.

Example 28 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. A coating solution prepared by dissolving 5 g in 70 ml of tetrahydrofuran was applied and dried so that the coating amount after drying was 10 g/m 2 .

The band "rrL characteristics of the electrophotographic photoreceptor thus prepared was measured in the same manner as in Example 1.

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

V□:+510V El/2:4. flux, sec ΔVO knee 20V Photomemory knee 15V Example 29 A polyvinyl alcohol film having a thickness of 0.5 pm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

Next, the dispersion of the disazo pigment used in Example 1 was placed on the polyvinyl alcohol layer formed previously so that the film thickness after drying was 0.
．． It was coated with a Mayer bar to a thickness of 5 μm and dried to form a charge generation layer.

Next, 5 g of a pyrazoline compound with the structural formula and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid)
was dissolved in 70 mJl of tetrahydrofuran and applied onto the charge generation layer so that the film thickness after drying was 15 lm.
It was dried to form a charge transport layer.

The electrophotographic photoreceptor thus produced was evaluated in the same manner as in Example 1. Show the results.

Vony 650V El/2: 2.11ux, sec Δ: +15V Photomemory, -1ov Example 30 An ammonia aqueous solution of casein (described above) was applied onto a 100 gm thick aluminum plate and dried to a film thickness of 0. A subbing layer of 5#Lm was formed.

Next, 5 g of 2,4.7-dolinitro-9-fluorenone
A charge transfer complex was prepared by dissolving 5 g of poly-N-vinylcarbazole (number average molecular weight: 300,000) in 70 m of tetrahydrofuran.

This charge transfer complex and exemplified pigment (9) Ig were added to a solution in which 5 g of polyester (trade name: Vylon, manufactured by Toyobo Co., Ltd.) was dissolved in 70 mfL of tetrahydrofuran, and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 12 gm, and dried to prepare an electrophotographic photoreceptor.

The charging characteristics were measured in the same manner as in Example 1.

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

V, ): +880V El/2: 3.9uux, see Example 31 The same charge transport layer and charge generation layer as in Example 1 were sequentially laminated on the casein layer of the casein layer-coated aluminum plate used in Example 1. An electrophotographic photoreceptor was prepared in exactly the same manner as in the example except that it had a one-layer structure, and its charging characteristics were measured in the same manner. The charging polarity at this time was set to 10. Show the results.

VQ: +595V El/2: 1.981ux, sec [Effects of the Invention] The electrophotographic photoreceptor of the present invention uses a specific disazo pigment in the photosensitive layer, thereby reducing carrier generation inside the photosensitive layer containing the disazo pigment. The electrophotographic photoreceptor has improved efficiency, carrier transport efficiency, or both, and has excellent sensitivity and potential stability during long-term use.

Claims (1)

[Claims] (1) An electrophotographic photoreceptor characterized by containing a disazo pigment represented by the following general formula (1) in a photosensitive layer. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) In the formula, R_1 represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, a heterocyclic group, or a halogen group, and R_2 and R_3 represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, a heterocyclic group, or a halogen group which may have a substituent, and A represents a coupler residue having a phenolic hydroxyl group.