JPH04288057A - Carbazole compound and electrtophotographic photoreceptor produced by using the same - Google Patents

Abstract

PURPOSE:To provide a new compound useful as an electrophotographic photoreceptor having excellent static chargeability, sensitivity and stability to repeated use. CONSTITUTION:The compound of formula I (R<1> is H, alkyl, aralkyl, aryl, condensed polycyclic group or heterocyclic group; R<2> and R<3> are H, alkyl, alkoxy, aryl, aralkyl or halogen; Ar<1> to Ar<4> are alkyl, aryl, condensed polycyclic group or heterocyclic group; Ar<1> and Ar<2> or Ar<3> and Ar<4> may together form a ring). The compound can be produced by reacting an aldehyde compound of formula II with a compound of formula III (R<4> is alkyl) in the presence of a base and reacting the obtained compound of formula IV with a hydrazine compound of formula V under acidic condition (with acetic acid, etc.) in a solvent (e.g. DMF) at a temperature between room temperature and 80 deg.C. An electrophotographic photoreceptor can be produced by applying a photosensitive layer containing the compound of formula I on an electrically conductive substrate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel carbazole compound and an electrophotographic photoreceptor using the same.

0002

BACKGROUND OF THE INVENTION In recent years, organic photoreceptors have been widely used as electrophotographic photoreceptors in image forming apparatuses such as copying machines, printers, facsimile machines, etc., as they are excellent in processability and economical efficiency and have a large degree of freedom in functional design. Further, when forming a copy image using an electrophotographic photoreceptor, the Carlson process is widely used. The Carlson process is
A charging process in which the photoconductor is uniformly charged by corona discharge, an exposure process in which the charged photoconductor is exposed to an original image to form an electrostatic latent image corresponding to the original image, and the electrostatic latent image is developed using toner. A developing process in which a toner image is formed by developing with a toner image, a transfer process in which the toner image is transferred to a base material such as paper, a fixing process in which the toner image transferred to the base material is fixed, and after the transfer process, a toner image is formed on the photoreceptor. and a cleaning step to remove residual toner. In this Carlson process,
In order to form high-quality images, an electrophotographic photoreceptor is required to have excellent charging characteristics and photosensitive characteristics, and to have a low residual potential after exposure.

Conventionally, inorganic photoconductors such as selenium and cadmium sulfide have been known as materials for electrophotographic photoreceptors.
These have the disadvantage of being toxic and having high production costs. Therefore, so-called organic electrophotographic photoreceptors using various organic substances in place of these inorganic substances have been proposed. Such an organic electrophotographic photoreceptor has a photosensitive layer composed of a charge-generating material that generates charges upon exposure to light, and a charge-transporting material that has a function of transporting the generated charges.

[0004] In order to satisfy various conditions desired for such an organic electrophotographic photoreceptor, it is necessary to appropriately select these charge generating materials and charge transporting materials. Various organic compounds have been proposed as charge transport materials.
Japanese Unexamined Patent Publication No. 58-65275, No. 57-148750
Carbazole compounds with various structures used as charge transporting materials are described in Japanese Patent Application No. 2003-120000, No. 58-140068, and the like. For example, the carbazole compound disclosed in JP-A-58-65275 has the structure of the following formula. This material is used as a hole transport material.

[0005]

[Chemical formula 3]

(wherein R1, R2, R3 and R
4 represents the group described in the above publication. )

[0007]

[Problems to be Solved by the Invention] However, the carbazole compounds described in the above-mentioned publication have a problem in that sensitivity and repeatability are insufficient. An object of the present invention is to solve these technical problems and provide an electrophotographic photoreceptor that is highly sensitive and has excellent repeatability.

[0008]

[Means and effects for solving the problems] The carbazole compound of the present invention for achieving the above object has the general formula (1):

[0009]

[C4]

(In the formula, R1 is a hydrogen atom, an alkyl group,
Represents an aralkyl group, an aryl group, a fused polycyclic group, or a heterocyclic group, and each of the alkyl group, aralkyl group, aryl group, fused polycyclic group, and heterocyclic group may have a substituent; R2 and R3 are the same or different and represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom, and each of the alkyl group, alkoxy group, aralkyl group, and aryl group may have a substituent. ;Ar1, Ar2, Ar3
and Ar4 are the same or different and represent an alkyl group, an aryl group, a fused polycyclic group, or a heterocyclic group, and any of these groups may have a substituent, and Ar1 and Ar2 and Ar3 and Ar4 are Each may form a ring. ).

The carbazole compound of the present invention is effective as a charge transport material, especially a hole transport material,
It has higher hole mobility than conventional charge transport materials such as carbazole compounds. Furthermore, the carbazole compound of the present invention has excellent compatibility with the binder resin and can form a uniform photosensitive layer, and the resulting photosensitive layer is also highly flexible.

Therefore, the electrophotographic photoreceptor of the present invention is characterized in that a photosensitive layer containing a carbazole compound represented by the above general formula (1) is provided on a conductive substrate. As a result, the electrophotographic photoreceptor of the present invention has excellent sensitivity and charging ability, and has high repeatability.Furthermore, the carbazole compound has excellent flexibility, so it can be used in the form of a small-diameter photoreceptor drum or belt. Even when used in the photosensitive layer, problems such as cracks do not occur in the photosensitive layer.

Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group,
Examples include isobutyl group, t-butyl group, pentyl group, and hexyl group. Examples of the aryl group include phenyl group, naphthyl group, biphenylyl group, anthryl group, and phenanthryl group.

Examples of the aralkyl group include benzyl group, α-phenethyl group, β-phenethyl group, 3-phenylpropyl group, benzhydryl group, and trityl group. Examples of the alkoxy group include methoxy group,
Examples include ethoxy group, isopropoxy group, butoxy group, t-butoxy group, and hexyloxy group.

Examples of halogen atoms include chlorine, iodine, bromine, and fluorine. As the fused polycyclic group, various fused polycyclic compounds such as triphenylene, pyrene,
Chrysene, naphthacene, picene, perylene, benzo [α
] Examples include residues such as pyrene, rubycene, coronene, and obalene. Examples of the heterocyclic group include thienyl group, pyrrolyl group, pyrrolidinyl group, oxazolyl group, isoxazolyl group, thiazolyl group, isothiazolyl group, imidazolyl group, 2H-imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyranyl group, and pyridyl group. group, piveridyl group, piperidino group, 3-morpholinyl group,
Examples include morpholino group and thiazolyl group.

[0016] Examples of substituents that may be substituted on the above groups include halogen atoms, amino groups that may have substituents (alkyl, etc.), hydroxyl groups, carboxyl groups that may be esterified, and cyano groups. , a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C6 alkenyl group that may have an aryl group, and the like. There may be two or more substituents, and two substituents may form a ring.

Furthermore, Ar1 and Ar2 and/or Ar3 and Ar4 may form a ring, and examples of such a ring include carbazole. Specific examples of the hydrazone compound represented by the general formula (1) include the following.

[0018]

[C5]

[0019]

[C6]

The compound represented by the general formula (1) is:
For example, it can be produced using the following reaction formula. Reaction formula:

[0021]

[C7]

(In the formula, R1, R2, R3, Ar1
, Ar2, Ar3 and Ar4 are the same as above,
R4 is an alkyl group. ) That is, by reacting an aldehyde compound represented by formula (a) with a compound represented by formula (b) in the presence of a base (sodium hydroxide, potassium hydroxide, etc.), formula (c) is obtained. The intermediate represented is obtained. The reaction is carried out in a solvent at a temperature of 10-80°C. As the solvent, for example, dimethylformamide, dimethyl sulfoxide, etc. can be used. Then, this intermediate compound (c) is reacted with a hydrazine compound represented by the formula (d) under acidic conditions with the addition of acetic acid or the like to obtain the compound (1) of the present invention. This reaction takes place between room temperature and 80°C.
The reaction can be carried out in the same solvent as above at a temperature of .

The photosensitive layer in the present invention has the general formula (1).
) Contains one or more compounds represented by: The photosensitive layer in the present invention includes a single-layer type in which a charge-generating material, a charge-transporting material, which is a compound represented by the general formula (1) and a binder resin, and a charge-generating layer and a charge-transporting layer are laminated. Although there is a laminated type, the photosensitive layer of the present invention can be applied to either type.

In order to obtain a laminated type electrophotographic photoreceptor, a charge generation layer containing a charge generation material is formed on a conductive base material, and a charge transport material having the above general formula is formed on this charge generation layer. A charge transport layer containing the represented compound may be formed. Furthermore, the stacking order may be reversed and the charge generation layer may be provided on the charge transport layer.

As charge generating materials, conventionally used selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salts, azo compounds, disazo compounds, phthalocyanine compounds, anthanthrone compounds, and perylene compounds are used. compounds, indigo-based compounds, triphenylmethane-based compounds, threne-based compounds, toluidine-based compounds, pyrazoline-based compounds, perylene-based compounds, quinacridone-based compounds, pyrrolopyrrole-based compounds, and the like. These charge generating materials can be used alone or in combination of two or more.

[0026] Furthermore, the compound represented by the above general formula, which is a charge transporting material, can be used in combination with other conventionally known charge transporting materials. Conventionally known charge transport materials include, for example, oxadiazole compounds such as 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazole, and 9-(4-diethylaminostyryl).
Styryl compounds such as anthracene, carbazole compounds such as polyvinylcarbazole, 1-phenyl-3-
Pyrazoline compounds such as (p-dimethylaminophenyl) pyrazole, triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazoles Examples include nitrogen-containing cyclic compounds such as system compounds, and fused polycyclic compounds. Note that a binder resin is not necessarily required when a charge transporting material having film-forming properties such as polyvinylcarbazole is used.

Various resins can be used as the binder resin, such as styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, and acrylic copolymers. Union,
Styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate , thermoplastic resins such as polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, silicone resin, epoxy resin, and other crosslinkable thermosetting resins, as well as photosensitive resins such as epoxy acrylate and urethane-acrylate. Examples include curable resins. These binder resins can be used alone or in combination of two or more.

[0028] Examples of the solvent for dissolving the charge generating material, charge transporting material and binder resin to prepare a coating solution include methanol, ethanol, isopropanol,
Alcohols such as butanol, aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene, and dimethyl ether. , ethers such as diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethyl formaldehyde, dimethyl formamide, and dimethyl sulfoxide. These solvents can be used alone or in combination of two or more.

Further, in order to improve the sensitivity of the charge generation layer, a known sensitizer such as terphenyl, halonaphthoquinones, acenaphthylene, etc. may be used together with the above charge generation material. Furthermore, a surfactant, a leveling agent, etc. may be used to improve the dispersibility, dyeability, etc. of the charge transport material and charge generation material.

[0030] Examples of the conductive substrate include aluminum, copper, tin, platinum, silver, vanadium, molybdenum,
Chromium, cadmium, titanium, nickel, palladium,
Single metals such as indium, stainless steel, and brass, and plastic materials on which the above metals are vapor-deposited or laminated;
Examples include glass coated with aluminum iodide, tin oxide, indium oxide, and the like.

The conductive substrate may be in the form of a sheet or a drum, as long as the substrate itself is conductive or the surface of the substrate is conductive. Also,
The substrate preferably has sufficient mechanical strength during use. In the laminated electrophotographic photoreceptor, the charge generation material and the binder resin constituting the charge generation layer can be used in various ratios, but 100 parts of the binder resin (parts by weight,
It is preferable to use 5 to 500 parts, particularly 10 to 250 parts, of the charge generating material (the same applies hereinafter).

[0032] The charge generation layer may have an appropriate thickness, but the thickness is 0.01 to 5 μm, particularly 0.1 to 3 μm.
It is preferable that the diameter is about m. The compound represented by the above general formula (1) (charge transport material) constituting the charge transport layer and the binder resin can be used in various ratios, but the charge generated in the charge generation layer by light irradiation can be 10 to 500 parts, especially 25 to 2 parts, of the compound represented by the above general formula is added to 100 parts of the binder resin so that it can be easily transported.
Preferably, it is used in a proportion of 0.00 parts.

The charge transport layer is preferably formed to have a thickness of about 2 to 100 μm, particularly about 5 to 30 μm. In a single-layer type electrophotographic photoreceptor, the amount of the charge generating material is 2 to 20 parts, especially 3 to 15 parts, and the amount of the compound represented by the above general formula (charge transporting material) is 40 to 40 parts per 100 parts of the binder resin. 2
00 parts, especially 50 to 150 parts is suitable. Further, the thickness of the single-layer type photosensitive layer is preferably about 10 to 50 μm, particularly about 15 to 30 μm.

When a photosensitive layer including a charge generation layer and a charge transport layer is formed by a coating method, the charge generation material or the charge transport material and the binder resin are coated by a conventionally known method such as a roll mill, a ball mill, an attritor, or a binder resin. Prepare the coating solution using a paint shaker, ultrasonic disperser, etc.

[0035]

[Examples] The present invention will be explained in detail below with reference to Examples and Comparative Examples. Example 1 <Synthesis of the compound represented by the above formula (2)> The following formula (1
To 30 g of 2,7-diformyl-N-phenylcarbazole represented by 2), 28 g of the compound represented by the following formula (13) was added in dimethylformamide at 50°C for 3 hours in the presence of sodium hydroxide. Made it react.

[0036]

[Chemical formula 8]

After isolation and purification of the product by conventional methods,
The mixture was reacted with 10 g of diphenylhydrazine (C6H5)2N-NH2 in ethyl alcohol under acidic conditions with stirring at room temperature to obtain a compound represented by the above formula (2). Elemental analysis value: Calculated value (%) as C45H33N3
C87.78 H5.40 N6.8
2 Actual value (%) C87.67 H5.45
Each compound was produced in the same manner as in Example 1 using appropriate starting materials with N of 6.88 or less. The obtained compounds are as follows. Example 2 <Compound represented by formula (3)> Elemental analysis value: Calculated value (%) as C48H39N3
C87.63 H5.98 N6.3
9 Actual value (%) C87.75 H5.91
N6.34 Example 3 <Compound represented by formula (4)> Elemental analysis value: Calculated value (%) as C37H33N3
C85.51 H6.40 N8.0
9 Actual value (%) C85.45 H6.43
N8.12 Example 4 <Compound represented by formula (5)> Elemental analysis value: Calculated value (%) as C52H36N3
C88.86 H5.16 N5.9
8 Actual value (%) C88.96 H5.15
N5.89 Example 5 <Compound represented by formula (6)> Elemental analysis value: Calculated value as C45H34N3 Cl (%
) C82.87 H5.25 N6
．． 44 Actual value (%) C82.89 H5.
26 N6.41 Examples 6 to 10 and Comparative Example 1
~3 (Laminated photosensitive layer) 2 parts of charge generating material, polyvinyl butyral resin (S-lecBM- manufactured by Sekisui Chemical Co., Ltd.)
5) and 120 parts of tetrahydrofuran were dispersed for 2 hours in a paint shaker using zirconia beads (2 mm diameter). The resulting dispersion was coated onto an aluminum sheet using a wire bar and heated at 100°C for 1
After drying for a period of time, a charge generation layer of 0.5 μm was obtained. The charge generating materials used are shown in Tables 1 and 2. In these tables, charge generating materials A, B and C in each example mean compounds represented by the following formulas (A), (B) and (C), respectively.

[0038]

[Chemical formula 9]

[0039] On this charge generation layer, one part of a charge transporting material and a polycarbonate resin ("Z-300" manufactured by Mitsubishi Gas Chemical Co., Ltd.
A solution prepared by dissolving 1 part of '') in 9 parts of toluene was applied using a wire bar and dried at 100°C for 1 hour to obtain a charge transport layer of 22 μm. The charge transport materials used in Examples 6 to 10 are represented by the compound numbers shown in the above-mentioned specific examples in Tables 1 and 2. In addition, the charge transport materials I to III used in Comparative Examples 1 to 3 have the following formulas (I) to (II), respectively.
It means a compound represented by I).

[0040]

[Chemical formula 10]

Examples 11 to 13 and Comparative Examples 4 to 6 (single layer type photosensitive layer) 1 part of charge generating material and 60 parts of tetrahydrofuran,
Dispersion was carried out for 2 hours using a paint shaker using zirconia beads (2 mm diameter). A tetrahydrofuran solution 5 of polycarbonate resin (“Z-300” manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a solid content of 20% by weight was added to the obtained dispersion.
0 parts and 10 parts of charge transport material were added and dispersion continued for an additional hour. The resulting dispersion was coated onto an aluminum sheet using a wire bar and dried at 100° C. for 1 hour to obtain a 20 μm photosensitive layer. In Tables 1 and 2, the charge-generating materials and charge-transporting materials used are represented by their respective chemical structural formula numbers, as in the above examples.

(Evaluation test) The surface potential, half-decreased exposure (E1/2) and residual potential of the photoreceptor obtained in each example and comparative example were measured using an evaluation tester ("EPA8100" manufactured by Kawaguchi Electric Co., Ltd.).
”). The measurement conditions are as follows. Light intensity: 50 lux Exposure intensity: 1/15 seconds Surface potential: The inflow current value was adjusted so as to be around (±)700V.

Light source: Tungsten lamp Static elimination: 200 lux Residual potential measurement: Measurement was started 0.2 seconds after the start of exposure. The test results of Examples 6 to 13 are shown in Table 1, and the test results of Comparative Examples 1 to 6 are shown in Table 2.

[0044]

[Table 1]

[0045]

[Table 2]

From these test results, the photosensitive layers of each example showed almost no difference in surface potential from the conventional photoconductor (comparative example), but were superior in half-life exposure and residual potential, and the sensitivity was significantly lower. You can see that it has been improved.

[0047]

As described above, the electrophotographic photoreceptor using the carbazole compound of the present invention has excellent sensitivity and repeatability.

Claims (2)

[Claims] Claim 1: General formula (1): [Formula 1] (wherein, R1 represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a fused polycyclic group, or a heterocyclic group; , the aryl group, the fused polycyclic group, and the heterocyclic group may each have a substituent; R
2 and R3 are the same or different and represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom, and the alkyl group, alkoxy group, aralkyl group, and aryl group may each have a substituent. Good; Ar1, Ar2, Ar3 and Ar
4 are the same or different and represent an alkyl group, an aryl group, a fused polycyclic group, or a heterocyclic group, and any of these groups may have a substituent, and Ar1 and Ar2 and Ar3 and Ar4 are each It may form a ring. ) A carbazole compound represented by 2. An electrophotographic photoreceptor characterized in that a photosensitive layer containing a carbazole compound represented by the following general formula (1) is provided on a conductive substrate. [Formula 2] (wherein, R1 represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a fused polycyclic group, or a heterocyclic group; Any of the ring groups may have a substituent; R
2 and R3 are the same or different and represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom, and the alkyl group, alkoxy group, aralkyl group, and aryl group may each have a substituent. Good; Ar1, Ar2, Ar3 and Ar
4 are the same or different and represent an alkyl group, an aryl group, a fused polycyclic group, or a heterocyclic group, and any of these groups may have a substituent, and Ar1 and Ar2 and Ar3 and Ar4 are each It may form a ring. )