JPH04328566A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain excellent sensitivity and high repetitive characteristics by forming a photosensitive layer contg. a specified hydrazone compd. on an electric conductive substrate. CONSTITUTION:A photosensitive layer contg. a hydrazone compd. represented by formula I is formed on an electric conductive substrate. In the formula I, each of Ar<1>-Ar<4> is H, alkyl, aryl, aralkyl or a heterocyclic group and this alkyl, aryl, aralkyl or heterocyclic group may have a substituent but Ar<3> and Ar<4> are not simultaneously H. The photosensitive layer is a single layer type one made of a mixture of an electric charge generating material with the hydrazone compd. represented by the formula I as an electric charge transferring material and a binding resin or a laminate type one formed by laminating an electric charge generating layer and an electric charge transferring layer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor suitable for use in image forming apparatuses such as copying machines.

0002

[Prior Art] In recent years, organic electrophotographic photoreceptors have been widely used as electrophotographic photoreceptors in image forming devices such as copying machines, printers, and facsimile machines, as they have excellent processability and economic efficiency, and have a large degree of freedom in functional design. There is. Further, when forming a copy image using an electrophotographic photoreceptor, the Carlson process is widely used. The Carlson process consists of a charging process in which a photosensitive layer is uniformly charged by corona discharge, an exposure process in which an original image is exposed to the charged photosensitive layer to form an electrostatic latent image corresponding to the original image, and an electrostatic latent image is transferred to a toner. A developing step of developing with a developer containing a toner image to form a toner image, a transfer step of transferring the toner image to a base material such as paper,
The method includes a fixing step for fixing the toner image transferred to the base material, and a cleaning step for removing toner remaining on the photosensitive layer after the transfer step. In this Carlson process, in order to form a high quality image, the electrophotographic photoreceptor is required to have excellent charging characteristics and photosensitivity 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. In addition, 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 that includes 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. In order to satisfy various conditions desired for such an organic electrophotographic photoreceptor, it is necessary to appropriately select the charge generating material and the charge transporting material.

[0004] Various organic compounds have been proposed as charge transport materials.
6, Japanese Unexamined Patent Publication No. 2-93466, etc. are known.

[0005]

[Problems to be Solved by the Invention] However, all of the electrophotographic photoreceptors using the compounds described in the above-mentioned publications have the drawbacks of insufficient sensitivity and poor repeatability. Therefore, an object of the present invention is to solve such technical problems and provide an electrophotographic photoreceptor having excellent sensitivity and high repeatability.

[0006]

[Means for Solving the Problems and Effects] In order to achieve the above object, the electrophotographic photoreceptor of the present invention has the general formula (1):

[0007]

[Case 2]

(In the formula, Ar1, Ar2, Ar3 and Ar4 are the same or different and represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group or a heterocyclic group, and the alkyl group, aryl group, aralkyl group and heterocyclic group are Both may have a substituent; however, Ar1 and Ar2 must not be hydrogen atoms at the same time.)
This is an electrophotographic photoreceptor characterized by being provided with a photosensitive layer containing a hydrazone compound represented by:

The compound of the present invention is effective as a charge transporting material, particularly as a hole transporting material, and has higher hole mobility than conventionally known charge transporting materials. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group,
Examples include t-butyl group, pentyl group, and hexyl group.

[0010] Examples of the aryl group include phenyl group,
Examples include 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 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, and pyranyl group. , pyridyl group, piperidyl group, piperidino group, 3-morpholinyl group,
Examples include morpholino group.

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

[0013] As specific hydrazone compounds represented by the general formula (1), the following can be exemplified.

[0014]

[Chemical formula 3]

[0015]

[C4]

[0016]

[C5]

[0017]

[C6]

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

[0019]

[Chemical 7]

(In the formula, Ar1, Ar2, Ar3 and Ar4 are the same as above, and X represents a halogen atom.)
That is, the compound represented by the general formula (1) is the compound represented by the formula (a) and the formula (b). Ul
lmann, Ber. , 36.2382 (1903) and F. Ullmann, Ber. ,38.2211(
It is synthesized according to the synthesis method shown in 1905).

The electrophotographic photoreceptor of the present invention contains one or more hydrazone compounds represented by the above general formula (1). In the present invention, the photosensitive layer includes a single layer type in which a hydrazone compound represented by the general formula (1) as a charge generation material and a charge transport material and a binder resin are mixed, and a charge generation layer and a charge transport layer. Although there is a laminated type, the electrophotographic photoreceptor of the present invention can be applied to either type.

In order to obtain a laminated type photosensitive layer, a charge generation layer containing a charge generation material is formed on a conductive substrate, and a charge transport material represented by the general formula (1) is formed on this charge generation layer.
What is necessary is to form a charge transport layer containing a hydrazone compound represented by: 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, perylene compounds, indigo compounds, triphenylmethane compounds, threne compounds, toluidine compounds, pyrazoline compounds, perylene compounds, Examples include quinacridone compounds and pyrrolopyrrole compounds. These charge generating materials can be used alone or in combination of two or more.

[0023] Furthermore, the charge transporting material having the general formula (1)
The hydrazone compound represented by ) can be used in combination with other conventionally known charge transport materials. Conventionally known charge transport materials include, for example, 2,5-di(4
Oxadiazole compounds such as -methylaminophenyl)-1,3,4-oxadiazole, styryl compounds such as 9-(4-diethylaminostyryl)anthracene, carbazole compounds such as polyvinylcarbazole, 1-phenyl- 3-(p-dimethylaminophenyl)
Pyrazoline compounds such as pyrazole, triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds,
Examples include nitrogen-containing cyclic compounds and fused polycyclic compounds such as thiadiazole compounds, imidazole compounds, pyrazole compounds, and triazole 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 resin, polyurethane resin, polycarbonate resin , thermoplastic resins such as polyarylate resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyether resins, silicone resins, epoxy resins, and other crosslinkable thermosetting resins, as well as epoxy acrylate resins, Examples include photocurable resins such as urethane-acrylate resins. These binder resins are 1
A species or a mixture of two or more kinds can be used.

[0025] 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 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.

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 photosensitive layer, the charge generating material and the binder resin constituting the charge generating layer can be used in various ratios. 5 to 500 parts of materials, especially 10 to 500 parts
Preferably, it is used in a proportion of 250 parts.

[0029] The charge generation layer may have an appropriate thickness, but it may have a thickness of 0.01 to 5 μm, particularly 0.1 to 3 μm.
It is preferable that the diameter is about m. A hydrazone compound represented by the above general formula (1) constituting the charge transport layer (
The charge transport material) and the binder resin can be used in various ratios, but in order to easily transport the charges generated in the charge generation layer by light irradiation, the charge transport material) and the binder resin may be used in proportions of 100 parts of the binder resin. It is preferable to use the hydrazone compound represented by the general formula (1) in an amount of 10 to 500 parts, particularly 25 to 200 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 photosensitive layer, the charge generating material is 2 to 20 parts, particularly 3 to 15 parts, based on 100 parts of the binder resin, and the amount of the charge generating material is 2 to 20 parts, particularly 3 to 15 parts, based on the general formula (
1) Hydrazone compound (charge transport material) represented by
is suitably 40 to 200 parts, particularly 50 to 150 parts. In addition, the thickness of the single-layer type photosensitive layer is 10 to 50 μm.
m, particularly preferably about 15 to 30 μm.

When a photoreceptor 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.

[0032]

[Examples] The present invention will be explained in detail below with reference to Examples and Comparative Examples. Examples 1 to 5 and Comparative Examples 1 to 3 (laminated photosensitive layer) 2 parts of charge generating material, 1 part of polyvinyl butyral resin, and 120 parts of tetrahydrofuran were dispersed for 2 hours in a paint shaker using zirconia beads (2 mm diameter). I let it happen. The resulting dispersion was applied onto an aluminum sheet using a wire bar, dried at 100°C for 1 hour, and coated with a 0.5μ
A charge generation layer of m was obtained. The charge generating materials used are shown in Table 1. In Table 1, charge generating materials A, B and C mean compounds represented by the following formulas (A), (B) and (C), respectively.

[0033]

[Chemical formula 8]

A solution prepared by dissolving 1 part of charge transporting material and 1 part of polycarbonate resin in 9 parts of toluene was applied onto this charge generation layer using a wire bar, and dried at 100°C for 1 hour.
A charge transport layer of 22 μm was obtained. In Table 1, Example 1
The charge transport materials used in ~5 are indicated by the compound numbers shown in the above-mentioned specific examples, and the charge transport materials I, II, and III used in Comparative Examples 1 to 3 have the following formulas (I),
It means compounds represented by (II) and (III).

[0035]

[Chemical formula 9]

[0036] Formula (I) is described in the above-mentioned Japanese Patent Application Laid-open No. 2-280.
168, formula (II) is disclosed in JP-A-1-237665, and formula (III) is disclosed in JP-A-2-93466. Examples 6 to 8 and Comparative Examples 4 to 6 (single-layer photosensitive layer) 1 part of a charge generating agent and 60 parts of tetrahydrofuran were dispersed for 2 hours in a paint shaker using zirconia beads (2 mm diameter). The resulting dispersion has a solid content of 2
Add 50 parts of a 0% by weight solution of polycarbonate resin in tetrahydrofuran and 10 parts of charge transport material;
Continued time distribution. The resulting dispersion was applied onto an aluminum sheet using a wire bar and dried at 100° C. for 1 hour to obtain a 20 μm photoreceptor. The charge-generating materials and charge-transporting materials used are shown in Table 2 by numbers attached to their respective chemical structural formulas, as in Table 1 of the above-mentioned Examples.

[Evaluation test of surface potential, residual potential, and half-life exposure amount] The surface potential, residual potential, and half-life exposure amount (E1/2) of the photoreceptors obtained in each example and comparative example were evaluated using an evaluation tester (Kawaguchi Electric Co., Ltd.). It was measured using "EPA8100" manufactured by 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 above measurement results are shown in Table 1 for Examples 1 to 5 and Comparative Examples 1 to 3, and Table 2 for Examples 6 to 8 and Comparative Examples 4 to 6, respectively.

[0039]

[Table 1]

[0040]

[Table 2]

[Evaluation test for repeated characteristics] The photoreceptors obtained in Examples 1 to 3 and Comparative Examples 1 and 2 above were tested using a copying machine (DC-111 manufactured by Sanda Kogyo Co., Ltd. modified to be negatively charged). Copying was performed for 1000 cycles, and the surface potential and blank paper potential before and after copying were measured. The measurement conditions (light intensity, exposure intensity, surface potential, light source and static elimination) are as follows:
Same as above.

[0042] These Examples 1 to 3 and Comparative Examples 1 and 2
Table 3 shows the above measurement results.

[0043]

[Table 3]

Regarding these test results, from Tables 1 and 2, the photoreceptors of Examples 1 to 8 have almost no difference in surface potential from conventional photoreceptors (Comparative Examples 1 to 6), but the residual potential and half-decreased Excellent in exposure amount (E1/2),
It can be seen that the sensitivity has been significantly improved. Also, Table 3
The photoreceptors of Examples 1 to 3 were compared to the conventional photoreceptor (Comparative Example 1).
, 2), both the surface potential and the white paper potential show smaller potential changes even when used repeatedly. In other words, it can be seen that the photoreceptor has excellent repeatability.

[0045]

As described above, according to the electrophotographic photoreceptor of the present invention, since a hydrazone compound having excellent charge transport ability is used as a charge transport material, it has excellent sensitivity and
It has the effect of having high repeatability.

Claims (1)

[Claims] [Claim 1] On a conductive substrate, compounds of the general formula (1): [Formula 1] (wherein Ar1 , Ar2 , Ar3 and Ar4
are the same or different and represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group;
All of the aryl group, aralkyl group, and heterocyclic group may have a substituent; however, Ar1 and Ar2
must not be hydrogen atoms at the same time. ) An electrophotographic photoreceptor comprising a photosensitive layer containing a hydrazone compound represented by: