JPH03179360A - Electrophotographic sensitive body - 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 an azo pigment having a coupler component having a specific structure.

[Conventional technology] Conventionally, 1! Inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as secondary photographic photoreceptors.

On the other hand, electrophotographic photoreceptors using organic photoconductive substances include photoconductive polymers typified by poly-N-vinylcarbazole and 2,5-bis(p-diethylaminophenyl)-1,3,4- Those using a low-molecular organic photoconductive substance such as oxadiazole, and those using a combination of such an organic photoconductive substance and 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 being extremely productive and providing inexpensive photoreceptors. In addition, it has the advantage that color sensitivity can be freely controlled by selecting the sensitizers used, such as dyes and pigments, and has been extensively studied. In particular, recent developments have led to the development of functionally separated photoreceptors 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 conductive substance. 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 pigment compounds with various properties can be easily obtained depending on the combination of the azo component and the coupler component, so a large number of pigment compounds have been proposed so far.

Couplers used in such azo pigments include naphthol AS compounds described in JP-A-47-375438, benzcarbazole-based compounds described in JP-A-53-95033, etc. Kaisho 54
Naphthalimide compounds described in JP-A-79632 and perinone compounds described in JP-A-57-176055 are already known.

However, electrophotographic photoreceptors using conventional azo 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.

[Problem to be solved by the invention] The purpose of the present invention is to provide a novel photoconductive material;
An object of the present invention is to provide an electrophotographic photoreceptor having practical high sensitivity characteristics and stable potential characteristics during repeated use.

[Means for Solving the Problems, Effects] The present invention provides an electrophotographic photoreceptor having a photosensitive layer containing an azo pigment on a conductive support, wherein the azo pigment is an azo pigment represented by the following general formula (1). It consists of an electrophotographic photoreceptor characterized by:

In the general formula, Ar represents an aromatic hydrocarbon group or a heterocyclic group which may have a substituent which may be bonded via a bonding group, and X represents a substituent which is integrated with a benzene ring. represents a residue necessary to form an aromatic hydrocarbon ring or an aromatic heterocycle which may be present, m is an integer of O or 1, and n is an integer of 1, 2 or 3.

In the azo pigment represented by the general formula (1), specific examples of Ar include aromatic hydrocarbon groups such as benzene, naphthalene, fluorene, phenanthrene, anthracene, and hyrene, furan, thiophene, pyridine, indole, benzothiazole, and cal/chloride. Heterocyclic groups such as zole, acridone, dibenzothiophene, benzoxazole, oxadiazole, thiazole, etc., and those in which the above aromatic hydrocarbon groups or heterocyclic groups are bonded directly or with an aromatic group or a non-aromatic group. , such as biphenylbinaphthyl, diphenylamine, triphenylamine, N-methyldiphenylamine, fluorenone, phenanthrequinone, anthraquinone, benzanthrone, terphenyl,
Diphenyloxazole, stilbene, distyrylbenzene, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, benzophenone, tetraphenyl-p-pyridylamine, tetraphenylbenzidine, N-phenyl-2-pyridylamine, N,N- Examples include groups such as diphenyl-2-pyridylamine.

Specific examples of X include aromatic hydrocarbon rings such as benzene and naphthalene, indole, carbazole, and benzcarbazole rings.

Examples of substituents for the above aromatic hydrocarbon group or heterocyclic group include alkyl groups such as methyl, ethyl, propyl, and butyl, flukoxy groups such as methoxy, ethoxy, and propoxy, fluorine atoms, chlorine atoms, Examples include halogen atoms such as bromine atoms, dialkylamino groups such as dimethylamino and diethylamine 7, hydroxy groups, nitro groups, cyano groups, and halomethyl groups.

Representative examples of the azo pigment represented by the general formula (1) are listed below, but the azo pigment is not limited to these.

In addition, How to write: Showing the basic type, to the basic type By describing only the changed parts.

Basic type 1 Exemplary pigment (1-1) m=0 Exemplary pigment (1 -2) m=　　0゜ Exemplary pigment (l -3) m=0, Exemplary pigment (l -4) A: +CH-CH (c arrow m=1 n=2 Exemplary pigment (1-5) m=0 n=3 Exemplary pigment (1-6) A: i1c-cn-@- m=1.

n=2 Exemplary pigment (1-7) m=0 n=2 Exemplary pigment (1-8) m=0.

n=2 Basic type 2 Example llI fee (2-1) A: ? N -@-C-CH-@- m=　0゜ n=2 Example face u (2-2) m=　0゜ n=2 Exemplary pigment (2-3) m=1, n=2 Exemplary pigment (2-4) m=0.

n=3 Exemplary pigment (2-5) m=1 n=2 Basic type 3 Exemplary pigment (3-1) m=0, n=1 Exemplary pigment (3-2) m=0.

n=2 Exemplary pigment (3-3) m=0 n=2 Exemplary pigment (3-4) m=o.

n=3 Basic type 4 Exemplary pigment (4-1) m = O.

n=2 R: hydrogen atom Exemplary class H (4-2) m=0, n+=2 :Chlorine atom Exemplary pigment (4-3) m=o, n=3 R: fluorine atom Exemplary pigment (4-4) Ar: 4 bats m=1.　n=2 R: hydrogen atom Exemplary pigment (4-5) A r: +N4t m=0. n=2 R: hydrogen atom Exemplary pigment (4-6) A r: -@-N-N-@- m=O1n=2 R: chlorine atom Exemplary pigment (4-7) A: m=o.

n=2 R: fluorine atom exemplified class N(4-8) m=0. n=2 R: methyl group exemplified pigment (4-9) m=o, n=2 R nibrome atom exemplified pigment (4-10) m=o, n=2 R: chlorine atom basic type 5 exemplified lIR pigment (5 -1) m=1, n=1 Exemplary Pigment (5-2) m=o, n=2 The coupler used in the synthesis of the azo pigment represented by the general formula (1) is, for example, 3-formyl-2-naphthol (the following It can be easily synthesized by a dehydration condensation reaction between a dicyanobarbituric acid derivative (a) and a dishanobarbituric acid derivative (a below) in the presence (or absence) of a base such as piperidine.

3 Coupler synthesis example (synthesis of the above coupler) 500mJ
3-formyl-2-naphthol (1) in 1 flask
．． 0 g (0,029 mol), 5.3 g (0,030 mol) of 2,2-dicyanobarbylic acid (produced by Nippon Steel) and 300 ml of ethanol were added, and the mixture was heated under reflux for about 1 hour.

After cooling, it was collected by filtration and heated and washed with ethanol four times. Yield 8.8g, yield 92% Azo pigment combination example (synthesis of exemplified pigment (1-1)) 300m
l In a beaker, add 150 mJ1 of water and 20 m J1 of concentrated hydrochloric acid (0.2
3 mol) and 6.7 g of 2,7-diamifluorenone (
0,032 mol), cooled to 0℃, and poured a solution of 4.6g (0,067 mol) of sodium nitrite dissolved in 10mM water into the liquid over 10 minutes while keeping the temperature below 5℃. dripped.

After stirring for 15 minutes, carbon filtration was performed, and in this solution, 5 g (0,096 mol) of sodium fluoride was added to 90 ml of water.
The precipitated boron fluoride salt was collected by filtration, washed with cold water, washed with acetonitrile, and dried under reduced pressure at room temperature.

Yield: 9.3 g, yield: 71.4% Next, add N,N-dimethylformamide (D
MF) Add 500 m of water, dissolve 6.6 g (0,020 mol) of the coupler powder produced in the above coupler synthesis example, cool the liquid temperature to 5°C, and then dissolve 4.1 g of the previously obtained borofluoride salt.
(0,010 mol) was dissolved, and then 2.6 g (0,026 mol) of triethylamine was added dropwise over 5 minutes. After stirring for 2 hours, the precipitated pigment was collected by filtration and diluted with DMF four times.

After washing three times with water, it was freeze-dried.

Yield: 5.6 g, Yield: 64.8% The electrophotographic photoreceptor of the present invention has the general formula (
It has a photosensitive layer containing the azo pigment shown in 1).

The form of the photosensitive layer may be any known form and L/1, but the photosensitive layer containing the azo pigment represented by the general formula (1) is used as a charge generation layer, and the charge generation layer contains a charge transport substance. A functionally separated type photosensitive layer in which a transport layer is laminated is particularly preferred.

In this case, the charge generation layer can be formed by coating a coating solution in which the above-mentioned azo pigment as a charge generation substance is dispersed together with a binder resin in an appropriate solvent onto the conductive support by a known method. It is desirable that the film thickness is, for example, 5 pm or less, preferably 0.01 to IBm.

The binder resins used here are selected from a wide range of insulating flanks or organic photoconductive polymers, including polyvinyl butyral, polyvinylbenzal, polyarylates, polycarbonates.

Polyester, phenoxy resin, cellulose resin, acrylic resin, polyurethane, etc. are preferable, and the content thereof in the charge generation layer is 80% by weight or less, preferably 4%.
The amount of Oi is % 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 such as cyclohexanone and methyl ethyl ketone, amides such as N,N-dimethylformamide, esters such as methyl acetate and ethyl acetate, toluene, xylene, Examples include aromatics such as chlorobenzene, alcohols such as methanol, ethanol, and 2-propanol, and aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichlorethylene.

The charge transport layer is arranged 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 as required and applying the solution. The film thickness is generally 5 to 40 pm, particularly 15 pm.
~30 ILm 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, thiazole-based, oxadiazole-based, pyrazole-based pyrazoline-based, thiadiazole-based, triazole-based compounds, etc. heterocyclic compound, p-
Hydrazone-based compounds such as diethylaminobenzaldehyde-N,N-diphenylhydrazone, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, α-phenyl-4'-N,N-diphenylaminostilbene, 5-[ 4-(di-p-tolylamino)benzylidene]-58-dibenzo[a, d] Styryl compounds such as cycloheptene, benzidine compounds, triarylmethane compounds, triphenylamine, or groups consisting mainly of these compounds Examples include polymers having it in the chain or side chain (eg, 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, an appropriate binder resin can be used, and specifically, acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, polyacrylamide, polyamide, Examples include insulating resins such as chlorinated rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

Examples of the conductive support 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, polyethylene terephthalate, acrylic resin, etc.) or conductive particles (e.g., carbon black, silver particles, etc.) coated with these metals or alloys by vacuum evaporation can be coated with a suitable binder resin. In addition, a material coated on a plastic or metal support, 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 Bm or less, preferably 0.11 to 3 g.
m is appropriate. The undercoat layer is casein, polyvinyl alcohol, nitrocellulose, polyamide (nylon 6,
Nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, aluminum oxide, etc.

Another specific example of the present invention is an electrophotographic photoreceptor containing an azo pigment represented by formula (1) and a charge transport material in the same layer. At this time, a charge transfer complex consisting of poly-N-vinylcarbazole and trifluorofluorenone 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 an azo pigment represented by the general formula (1) and a charge transporting substance are dispersed in a suitable resin solution.

The general formula used in any electrophotographic photoreceptor (
The crystal form of the azo pigment represented by formula (1) may be amorphous or crystalline, and if necessary, two or more types of azo pigments represented by general formula (1) may be combined, or a known charge type may be used. It is also possible to use it in combination with generated 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.

Examples 1 to 20 5 g of methoxymethylated nylon (average molecular weight 32,000) and 10 g of alcohol-soluble copolymerized nylon (average molecular weight 29,000) were placed on an aluminum support in methanol 95°C.
A liquid solution dissolved in 10 g was applied with a Mayer bar, and a layer with a film thickness of Igm after drying was provided.

Next, 5 g of exemplified pigment (1-1) 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 20 hours. This dispersion was applied onto the previously formed undercoat layer using a Mayer bar so that the film thickness after drying was 0.2 gm.
It was dried to form a charge generation layer.

Next, 5 g of a hydrazone compound with the following structural formula and 5 g of polymethyl methacrylate (number average molecular weight 10,000) were dissolved in 40 m of chlorobenzene, and this was poured onto the charge generation layer so that the film thickness after drying was 20 gm. The electrophotographic photoreceptor of Example 1 was prepared by coating with a bar and drying to form a charge transport layer. The following exemplified pigment was used in place of exemplified class 1t(1-1), and the other conditions were the same as in Example 1.

Electrophotographic photoreceptors corresponding to Examples 2 to 20 were produced.

The electrophotographic photoreceptor produced in this way was tested using an electrostatic copying paper tester (Kawaguchi Electric Co., Ltd. Model 5P-428).
) was used to negatively charge the sample with a corona discharge of 13 KV, and after being held in a dark place for 1 second, the sample was exposed to light using a halogen lamp at an illuminance of 10 lux to evaluate the charging characteristics.

As for the charging characteristics, the surface potential (■0) and the exposure amount (El/2) required for the surface potential to attenuate to 1/2 after being left in a dark place were measured. Show the results.

V −V El/2 lux* 5ec1
(1-1) 705 2.42 (1-2
) 695 2.73 (1-4)
690 3.64 (1-5)' 700
2゜65 (1-6) 710
3.46 (1-7) 705
2.57 (1-8) 705
2.48 (2-2) 695
3.29 (2-3) 70
0 2.810 (3-2)
705 2.111 (3-3)
695 4.612 (3-4)
700 3.613 (4-1)
700 2.414 (4-2
) 705 2.215 (4
-4) 705 3.516 (
4-6) 700 2.217
(4-9) 710 3.418
(4-10) 710 2.31
9 (5-1) 695 4.
120 (5-2) 695
3.8 Comparative Examples 1 and 2 Electrophotographic photoreceptors corresponding to Comparative Examples 1 and 2 were produced in the same manner as in Example 1, except that Azoface Nene 4 having the following structural formula was used. Charging characteristics were evaluated in the same manner. Show the results.

(Comparative Example 1) Comparative Pigment (1) vo knee 700V El/2: 6.29. ux・(Comparative Example 2) Comparative Pigment (2) e C vo knee 680V El/2: 7. 41 ux-sec From these results, it can be seen that all the electrophotographic photoreceptors of the present invention have sufficient charging ability and excellent sensitivity.

Examples 21 to 23 Using the electrophotographic photoreceptors prepared in Examples 1, 2 and 3, fluctuations in dark area potential and bright area potential during repeated use were measured.

The method involves placing an electrophotographic photoreceptor in the cylinder of an electrophotographic copying machine equipped with a -6.5 KV corona charger, an exposure optical system, a developing device, a transfer charger, a Tl'i'A light optical system, and a cleaner. Pasted.

This copying machine is configured to produce an image on transfer paper as the cylinder is driven.

Using this copying machine, the initial dark area potential vD and bright area potential VL are
were set at around -7O0V and -2O0V, respectively, and the amount of variation ΔVD in the dark potential and the amount ΔvLt of variation in the bright potential when used repeatedly 5,000 times were measured. Show the results.

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

21 1 -15
+1522 2 -15
+2023 3 -
20 +15 Comparative Examples 3 and 4 The electrophotographic photoreceptors prepared in Comparative Examples 1 and 2 were carried out g4
The amount of potential fluctuation during repeated use was measured using the same method as No. 21. Show the results.

3 1 -30 +7
04 2 -45 +
85 From the results of Examples 21 to 23 and Comparative Examples 3 and 4,
It can be seen that the electrophotographic photoreceptor of the present invention has little potential fluctuation during repeated use.

Example 24 A subbing layer of polyvinyl alcohol having a thickness of 0.5 ILm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

A pigment dispersion of the exemplary pigment (1-1) used in Example 1 was applied onto this using a Mayer bar and dried to give a film thickness of 0.2 pm.
A charge generation layer was formed.

Next, a solution prepared by dissolving 5 g of a styryl compound of the following structural formula and 5 g of polycarbonate (average molecular weight 55,000) in 40 mjL of tetrahydrofuran was applied onto the charge generation layer and dried to form a charge transport layer with a film thickness of 20 gm. did.

The charging characteristics and durability characteristics of the electrophotographic photoreceptor thus prepared were evaluated by the same methods as in Examples 1 and 21. Show the results.

vo knee 705V El/2 two 2, 6jLux* secΔ
VO knee 10V ΔyL: +20V Example 25 An electrophotographic photoreceptor was prepared by applying the charge generation layer and charge transport layer of the electrophotographic photoreceptor prepared in Example 24 in the reverse order, and charged in the same manner as in Example 1. Characteristics were evaluated. however,
The charging was positive.

Show the results.

V, ): +680V El/2: 5.21ux-see Example 26 On the charge generation layer prepared in Example 1, 2, 4, 7-
) IJ nitro-9-fluorenone 5g and poly-4,4
°-Dioxydiphenyl-2,2-propane carbonate (molecular weight 300,000) 5g with 50mf of tetrahydrone
The film thickness after drying the coating solution prepared by dissolving it in L is 18gm.
A charge transport layer was formed by coating and drying.

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

However, the charging was positive. Show the results.

VO: +695V El/2: 6.0Jlux @ sec Example 27 0.5g of exemplified pigment (4-2) was mixed with 9.5g of cyclohexanone
The mixture was dispersed in a paint shaker with g for 5 hours. A solution prepared by dissolving 5 g of the charge transport material used in Example 1 and 5 g of polycarbonate in 40 g of tetrahydrofuran was added to this.
It was further shaken for 1 hour. The coating solution thus prepared was applied onto an aluminum support using a Mayer bar and dried to form a photosensitive layer having a thickness of 20 μm.

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

V, ): +705V El/2: 4.6Mux@sec [Effects of the Invention] The electrophotographic photoreceptor of the present invention uses an azo pigment having a specific structure in the photosensitive layer, thereby reducing charge carriers inside the photosensitive layer. Either or both of the generation efficiency and the injection efficiency are improved, and it has characteristics that are excellent in sensitivity and potential stability during repeated use.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a photosensitive layer containing an azo pigment on a conductive support, the azo pigment has the following general formula (1
) An electrophotographic photoreceptor characterized by being an azo pigment. General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼ (1) In the formula, Ar represents an aromatic hydrocarbon group that may have a substituent that may be bonded via a bonding group, or a heterocyclic group. where X represents a residue necessary to form an aromatic hydrocarbon ring or aromatic heterocycle which may have a substituent by condensation with a benzene ring, m is an integer of 0 or 1, n is an integer of 1, 2 or 3.