JPH04324449A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain high sensitivity by forming a photosensitive layer contg. a specified triphenylbenzene deriv. CONSTITUTION:A photosensitive layer contg. a compd. represented by formula I is formed on an electric conductive substrate. In the formula I, each of R1-R6 is alkyl or phenyl which may have a substituent and each of l, m and n is an integer of 0-3 but all of (l), (m) and (n) are not 0. The alkyl is straight chain or branched 1-6C alkyl such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl or hexyl. The substituent may be 1-6C lower alkyl, 1-6C alkoxy such as methoxy, ethoxy, propoxy or isopropoxy or aryl such as phenyl, naphthyl, biphenylyl or anthryl.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor.

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.
For example, JP-A-2-118666 describes the use of a triphenylbenzene derivative represented by the following general formula (20). General formula (20):

[0005]

[Case 2]

(In the formula, R11 and R12 represent R1 and R2 described in the above publication.)

[0007]

[Problems to be Solved by the Invention] However, the photoreceptor using the compound described in the above-mentioned publication as a charge transporting material had a problem of insufficient sensitivity. An object of the present invention is to solve such technical problems and provide a highly sensitive electrophotographic photoreceptor.

[0008]

[Means and effects for solving the problems] In order to achieve the above object, the electrophotographic photoreceptor of the present invention has a triphenylbenzene derivative represented by the following general formula (1) on a conductive base material. It is characterized in that it is provided with a photosensitive layer containing. General formula (1):

[0009]

[Chemical formula 3]

(In the formula, R1, R2, R3, R4
, R5 and R6 are the same or different and represent an alkyl group or a phenyl group which may have a substituent, and l
, m and n represent integers from 0 to 3. However, l, m and n are not 0 at the same time. ) The triphenylbenzene derivative of the above general formula (1) has a longer conjugated system and has a longer hole movement distance within the molecule than charge transport materials such as the triphenylbenzene derivative of the general formula (20). ,
It exhibits high hole mobility and is effective as a charge transport material, especially a hole transport material.

Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group,
Examples include straight-chain or branched alkyl groups having 1 to 6 carbon atoms such as isobutyl group, t-butyl group, pentyl group, and hexyl group. Examples of substituents that can be substituted on the phenyl group include the above-mentioned lower alkyl groups having 1 to 6 carbon atoms; methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, hexyloxy, etc. Alkoxy group having 1 to 6 carbon atoms; phenyl group, naphthyl group,
Examples include aryl groups such as biphenylyl group, anthryl group, and phenanthryl group.

Specific examples of the triphenylbenzene derivative represented by the general formula (1) include those shown below.

[0013]

[C4]

[0014]

[C5]

[0015]

[C6]

Various reaction schemes can be adopted for producing the compound represented by the above general formula (1). A method for introducing phenyl groups, in which groups are preliminarily placed at the 4-position of each of the three phenyl groups of triphenylbenzene:

001
7]

[C7]

Introducing a -CH2 CHO group via
Examples include a method of reacting this with a predetermined amine compound. The photosensitive layer in the present invention has the general formula (1)
Contains one or more compounds represented by: In addition, the photosensitive layer in the present invention may include a single-layer type in which a compound represented by the general formula (1) as a charge-generating material and a charge-transporting material and a binder resin are mixed, and a charge-generating layer and a charge-transporting layer. Although there is a laminated type photoreceptor, the photoreceptor of the present invention can be applied to either type.

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

[0020] Furthermore, the charge transport material having the general formula (1)
The triphenylbenzene compound represented by ) can be used in combination with other conventionally known charge transport materials. Conventionally known charge transport materials include, for example, 2,
Oxadiazole compounds such as 5-di(4-methylaminophenyl)-1,3,4-oxadiazole, 9-
Styryl compounds such as (4-diethylaminostyryl)anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3-(p-dimethylaminophenyl) pyrazole, triphenylamine compounds, indole compounds , oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, and other nitrogen-containing cyclic 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.

[0022] 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.

[0024] 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 generated material, especially 10 to
Preferably, it is used in a proportion of 250 parts.

[0026] 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 it be formed to a certain degree. A compound represented by the above general formula (1) constituting the charge transport layer (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 general formula (1 ) 10 to 500 parts, especially 25 parts
Preferably, it is used in a proportion of 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, and the compound represented by the above general formula (charge transporting material) is 40 to 200 parts based on 100 parts of the binder resin. , particularly from 50 to 150 parts. 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 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.

[0029]

[Examples] The present invention will be explained in detail below with reference to Examples and Comparative Examples. Examples 1 to 6 and Comparative Example 1 (Laminated photosensitive layer) The following formula (
2 parts of the charge generating material represented by A), 1 part of polyvinyl butyral resin, and 120 parts of dichloromethane were dispersed for 2 hours in a paint shaker using glass beads. 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.

On this charge generation layer, the above formulas (11) to (
16) A solution prepared by dissolving 1 part of the charge transport material represented by (Examples 1 to 6) or the following formula (21) (Comparative Example 1) and 1 part of polycarbonate resin in 120 parts of benzene was applied using a wire bar. , and dried at 150° C. for 1 hour to obtain a charge transport layer of 22 μm. Formula (A):

[0031]

[Chemical formula 8]

Formula (21):

[0033]

[Chemical formula 9]

Examples 7 to 12 and Comparative Example 2 (single-layer photosensitive layer) 1 part of the charge generating agent represented by the above formula (A) and 60 parts of dichloromethane were mixed for 2 hours in a paint shaker using stainless steel beads. Dispersed. To the obtained dispersion, 50 parts of a dichloromethane solution of polycarbonate resin with a solid content of 20% by weight and the above formulas (11) to (16) (
10 parts of the charge transport material represented by Examples 7 to 12) or formula (21) (Comparative Example 2) were added, and dispersion was continued for an additional hour. The resulting dispersion was coated onto an aluminum sheet using a wire bar, dried at 60°C for 1 hour, and coated with a 20μ
A photosensitive layer of m was obtained.

(Evaluation test) Surface potential of electrophotographic photoreceptors obtained in Examples 1 to 12 and Comparative Examples 1 to 2, half-decreased exposure amount (
E1/2) and residual potential were measured using an evaluation tester ("EPA8100" manufactured by Kawaguchi Electric Co., Ltd.). The measurement conditions are as follows.

Light intensity: 50 lux Exposure time: 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 1 to 6 and Comparative Example 1 are shown in Table 1, and the test results of Examples 7 to 12 and Comparative Example 2 are shown in Table 2.

[0038]

[Table 1]

[0039]

[Table 2]

From these test results, the electrophotographic photoreceptors of each example showed almost no difference in surface potential from the conventional photoreceptor (comparative example), but the half-reduction exposure of Comparative Examples 1 and 2 was not measurable. It can be seen that the electrophotographic photoreceptors of each example were excellent in half-life exposure and residual potential, and that the sensitivity was significantly improved.

[0041]

As described above, the electrophotographic photoreceptor of the present invention has high sensitivity because it is provided with a photosensitive layer containing a specific triphenylbenzene derivative having excellent electron transport ability.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer containing a triphenylbenzene derivative represented by the following general formula (1). General formula (1): [Formula 1] (wherein, R1, R2, R3, R4, R5 and R6 are the same or different and represent an alkyl group or a phenyl group which may have a substituent, l, m and n
represents an integer from 0 to 3. However, l, m and n are not 0 at the same time. )