JP2644925B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus such as a facsimile.

[0002]

2. Description of the Related Art In recent years, as an electrophotographic photosensitive member in an image forming apparatus such as a copying machine, an organic photosensitive member which is excellent in workability and economical efficiency and has a large degree of freedom in functional design has been widely used.

In the case where a copy image is formed using an electrophotographic photosensitive member, the Carlson process is widely used. The Carlson process includes a charging process for uniformly charging a photoconductor by corona discharge, an exposure process for exposing an original image on the charged photoconductor to form an electrostatic latent image corresponding to the original image, and a toner image forming process. A developing step of developing with a developer containing a toner image to form a toner image, a transferring step of transferring the toner image to a base material such as paper, a fixing step of fixing the toner image transferred to the base material, and after the transferring step And a cleaning step of removing the toner remaining on the photoreceptor. In the Carlson process, in order to form a high-quality image, it is required that the electrophotographic photosensitive member has excellent charging characteristics and photosensitive characteristics, and that the residual potential after exposure is low.

Conventionally, inorganic photoconductors such as selenium and cadmium sulfide have been known as electrophotographic photoreceptor materials.
They are toxic and have the disadvantage of high production costs. Therefore, so-called organic electrophotographic photoreceptors using various organic substances instead of these inorganic substances have been proposed. Such an organic electrophotographic photoreceptor has a photosensitive layer composed of a charge generation material that generates a charge upon exposure and a charge transport material having a function of transporting the generated charge.

In order to satisfy various conditions desired for such an organic electrophotographic photoreceptor, it is necessary to appropriately select these charge generation materials and charge transport materials. As the charge transport material, various organic compounds have been proposed and commercialized. For example, hydrazone compounds disclosed in JP-A-54-59143 and JP-A-2-210451 are known.

[0006]

However, the conventional charge transport material has a disadvantage that the sensitivity and the repetition characteristics are not sufficient. An object of the present invention is to solve such a technical problem and to provide an electrophotographic photosensitive member having high sensitivity and excellent repetition characteristics.

[0007]

According to the present invention, there is provided an electrophotographic photoreceptor comprising a photosensitive layer containing a compound represented by the following general formula on a conductive substrate. Electrophotographic photoreceptor.

[0008]

Embedded image

(Wherein R ¹ and R ² are the same or different and each is a hydroxyl group, a nitro group, a cyano group, a halogen atom, an alkanoyl group, an alkenyl group, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, a condensed polycyclic group) A alkanoyl group, an alkenyl group, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, a condensed polycyclic group and a heterocyclic group, each of which may have a substituent; And m are each an integer of 2 or 3;
R ³ represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a condensed polycyclic group or a heterocyclic group, and the alkyl group, aralkyl group, aryl group, condensed polycyclic group and heterocyclic group are each substituted. May have a group; Ar ¹
And Ar ² are the same or different and represent an aryl group, an alkyl group, a fused polycyclic group or a heterocyclic group, and any of the groups may have a substituent; Ar ³ and Ar ⁴ are the same or different Represents a hydrogen atom, an alkyl group, an aryl group, a condensed polycyclic group or a heterocyclic group, and the alkyl group, the aryl group, the condensed polycyclic group and the heterocyclic group each may have a substituent However, both Ar ³ and Ar ⁴ must not be hydrogen atoms, and Ar ¹ and Ar ² or Ar ³ and Ar ⁴ may form a ring together.) The alkanoyl group includes Examples include a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a pentanoyl group, and a hexanoyl group.

As the alkenyl group, for example, a vinyl group,
Examples include an allyl group, a crotyl group, a 2-pentenyl group, and a 2-hexenyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, and a hexyl group.

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

Examples of the halogen atom include fluorine, chlorine, bromine and iodine. Examples of the condensed polycyclic group include a naphthyl group and a phenanthryl group. As the heterocyclic group, for example, thienyl group, pyrrolyl group, pyrrolidinyl group, oxazolyl group, isoxazolyl group,
Thiazolyl group, isothiazolyl group, imidazolyl group, 2
H-imidazolyl group, pyrazolyl group, triazolyl group,
Examples thereof include a tetrazolyl group, a pyranyl group, a pyridyl group, a piberidyl group, a piperidino group, a 3-morpholinyl group, a morpholino group, and a thiazolyl group. Further, it may be a heterocyclic group condensed with an aromatic ring.

Examples of the substituent include a halogen atom, an amino group, a hydroxyl group, a carboxyl group which may be esterified, a cyano group, a C ₁ -C ₆ alkyl group,
Examples thereof include a C ₁ -C ₆ alkoxy group and a C ₂ -C ₆ alkenyl group which may have an aryl group. Also, A
r ¹ and Ar ² or Ar ³ and Ar ⁴ may be combined to form a ring, and examples of such a ring include carbazole.

Specific examples of the hydrazone compound represented by the above general formula include the following.

[0015]

Embedded image

[0016]

Embedded image

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

[0020]

Embedded image

[0021]

Embedded image

The compound represented by the above general formula can be obtained by reacting a corresponding aldehyde compound with a hydrazine compound in a solvent in the presence or absence of a catalyst. The photosensitive layer in the invention contains one or more compounds represented by the above general formula.

The photosensitive layer in the present invention has a single layer type in which a charge generation material, a compound represented by the above general formula, which is a charge transport material, and a binder resin are mixed, and a charge generation layer and a charge transport layer are laminated. Although there is a laminated type, the photosensitive layer of the present invention can be applied to any of them. In order to obtain a laminated electrophotographic photoreceptor, a charge generation layer containing a charge generation material is formed on a conductive substrate, and on this charge generation layer, a charge transport material represented by the above general formula What is necessary is just to form the charge transport layer containing a compound. Also, reverse the stacking order,
A charge generation layer may be provided on the charge transport layer.

Examples of the charge generating material include selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salts, azo compounds, disazo compounds, phthalocyanine compounds, anthanthrone compounds, and perylene compounds which have been conventionally used. Compounds, indigo compounds, triphenylmethane compounds, sulene compounds, toluidine compounds, pyrazoline compounds, perylene compounds, quinacridone compounds, pyrrolopyrrole compounds and the like. These charge generation materials can be used alone or in combination of two or more.

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 polyvinyl carbazole, 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 a nitrogen-containing cyclic compound such as a system compound and a condensed polycyclic compound. In the case where a charge transporting material having a film forming property such as polyvinyl carbazole is used, a binder resin is not necessarily required.

Various resins can be used as the binder resin, for example, styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic copolymers. Coalesce, 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, Thermoplastic resins such as polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, silicone resin, epoxy resin, other crosslinkable thermosetting resins, epoxy acrylate, urethane acrylate How such photocurable resins. These binder resins can be used alone or in combination of two or more.

Examples of the solvent for dissolving the charge generating material, the charge transport material and the binder resin to form a coating solution include alcohols such as methanol, ethanol, isopropanol and butanol, n-hexane, octane and cyclohexane. Aliphatic hydrocarbons such as benzene, toluene, xylene, etc., halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc. Ethers, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide and dimethyl Sulfoxide and the like.
These solvents can be used alone or in combination of two or more.

In order to improve the sensitivity of the charge generation layer, a known sensitizer such as terphenyl, halonaphthoquinones, acenaphthylene and the like may be used together with the charge generation material. Further, a surfactant, a leveling agent, and the like may be used to improve the dispersibility, dyeing property, and the like of the charge transporting material and the charge generating material.

As the conductive substrate, for example, aluminum, copper, tin, platinum, silver, vanadium, molybdenum,
Chrome, cadmium, titanium, nickel, palladium,
Simple metals such as indium, stainless steel, brass, etc., and plastic materials on which the above metals are 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, a drum, or the like, as long as the substrate itself has conductivity or the surface of the substrate has conductivity. Also,
The substrate preferably has a sufficient mechanical strength when used. In the laminated electrophotographic photoreceptor, the charge generation material and the binder resin constituting the charge generation layer can be used in various ratios, and 100 parts of the binder resin (parts by weight,
It is preferable to use 5 to 500 parts, especially 10 to 250 parts of the charge generating material with respect to the same.

The charge generation layer may have an appropriate thickness, but may have a thickness of 0.01 to 5 μm, especially 0.1 to 3 μm.
m. The compound (charge-transporting material) represented by the above general formula and the binder resin constituting the charge-transporting layer can be used in various ratios, but the charge generated in the charge-generating layer by light irradiation is easily reduced. It is preferable to use the compound represented by the above general formula at a ratio of 10 to 500 parts, particularly 25 to 200 parts, based on 100 parts of the binder resin so that the resin can be transported.

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

When the photosensitive layer including the charge generating layer and the charge transporting layer is formed by a coating means, the charge generating material or the charge transporting material and the binder resin are prepared by a conventionally known method, for example, a roll mill, a ball mill, an attritor, A coating solution is prepared using a paint shaker, an ultrasonic disperser, or the like.

[0034]

According to the constitution of the present invention, the compound represented by the above general formula has excellent charge transporting ability. By incorporating this compound into the photosensitive layer as a charge transporting material, the compound has excellent sensitivity and charging ability. Thus, an electrophotographic photosensitive member having high repetition characteristics can be obtained.

[0035]

The present invention will be described below in detail with reference to examples and comparative examples. Examples 1 to 9 and Comparative Examples 1 to 5 (laminated photosensitive layer) 2 parts of a charge generating material, 1 part of a polyvinyl butyral resin (“S-lecBM-5” manufactured by Sekisui Chemical Co., Ltd.), and 120 parts of tetrahydrofuran were mixed with zirconia. The mixture was dispersed for 2 hours with a paint shaker using beads (2 mm diameter). The obtained dispersion was applied on an aluminum sheet using a wire bar, and dried at 100 ° C. for 1 hour to obtain a 0.5 μm charge generation layer. The charge generation materials used are shown in Tables 1 and 2. In these tables, the charge generating materials A, B and C mean compounds represented by the following formulas (A), (B) and (C), respectively.

[0036]

Embedded image

On this charge generation layer, 1 part of a charge transport material and a polycarbonate resin (“Z-30” manufactured by Mitsubishi Gas Chemical Company, Inc.)
0 ") A solution prepared by dissolving 1 part in 9 parts of toluene was applied by a wire bar, and dried at 100 ° C. for 1 hour to obtain a 22 μm charge transport layer. The charge transport materials used in Examples 1 to 9 are shown in Tables 1 and 2 by the numbers of the compounds shown in the above specific examples. In addition, the charge transport materials IV used in Comparative Examples 1 to 5 mean compounds represented by the following formulas (I) to (V), respectively.

[0038]

Embedded image

Examples 10 to 14 and Comparative Examples 6 to 10
(Single-layer type photosensitive layer) One part of a charge generating agent and 60 parts of tetrahydrofuran were dispersed in a paint shaker using zirconia beads (2 mm diameter) for 2 hours. To the obtained dispersion, 50 parts of a tetrahydrofuran solution of a polycarbonate resin (“Z-300” manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a solid content of 20% by weight and 10 parts of a charge transport material were added.
Time dispersion continued. The obtained dispersion was applied on an aluminum sheet using a wire bar, and dried at 100 ° C. for 1 hour to obtain a photosensitive layer having a thickness of 20 μm. The charge generating materials and the charge transporting materials used are represented by the numbers of the respective chemical structural formulas in Tables 1 and 2, as in the above Examples.

(Evaluation Test) The surface potential, half-exposure (E _1/2 ) and residual potential of the photoreceptors obtained in each of the examples and comparative examples were evaluated using a tester (“EPA8100” manufactured by Kawaguchi Electric Co., Ltd.).
Was measured. The measurement conditions are as follows. Light intensity: 50 lux Exposure intensity: 1/15 sec Surface potential: (±) The flowing current was adjusted so as to be around 700 V.

Light source: tungsten lamp Static elimination: 200 lux Residual potential measurement: Measurement was started 0.2 seconds after the start of exposure. Table 1 shows the test results of Examples 1 to 14, and Table 2 shows the test results of Comparative Examples 1 to 10.

[0042]

[Table 1]

[0043]

[Table 2]

From these test results, the photosensitive layer of each example has almost no difference in surface potential from the conventional photosensitive member (comparative example), but is excellent in half-exposure amount and residual potential, and has remarkable sensitivity. It can be seen that it has been improved.

[0045]

As described above, according to the electrophotographic photoreceptor of the present invention, since a specific compound having excellent charge transporting ability is used as a charge transporting material, the sensitivity is excellent in addition to the charging ability. This has the effect.

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing a compound represented by the following general formula on a conductive substrate. Embedded image (Wherein R ¹ and R ² are the same or different and each represents a hydroxyl group,
Nitro group, cyano group, halogen atom, alkanoyl group,
An alkenyl group, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, a condensed polycyclic group or a heterocyclic group; The group and the heterocyclic group each may have a substituent;
n and m each represent an integer of 2 or 3; R ³ represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a condensed polycyclic group or a heterocyclic group, and is an alkyl group, an aralkyl group, an aryl group, a condensed polycyclic group; The cyclic group and the heterocyclic group may each have a substituent; Ar ¹ and Ar ² may be the same or different and represent an aryl group, an alkyl group, a condensed polycyclic group or a heterocyclic group; May also have a substituent; Ar ³ and Ar ⁴ may be the same or different and represent a hydrogen atom, an alkyl group, an aryl group, a condensed polycyclic group or a heterocyclic group, and an alkyl group, an aryl group And the condensed polycyclic group and the heterocyclic group each may have a substituent; provided that Ar ³ and Ar ⁴ must not both be hydrogen atoms, and Ar ¹ and Ar ² or Ar ³
And Ar ⁴ may together form a ring)