JP3115346B2 - 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 an electrophotographic photosensitive member suitably used for an image forming apparatus such as a copying machine.

[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, a printer, a facsimile, etc., an organic electrophotographic photosensitive member having excellent workability and economy and a large degree of freedom in functional design has been widely used. I have. When a copy image is formed using an electrophotographic photosensitive member, the Carlson process is widely used. The Carlson process includes a charging step of uniformly charging the photosensitive layer by corona discharge, an exposure step of exposing a document image to the charged photosensitive layer to form an electrostatic latent image corresponding to the document image, and a toner image forming step. A developing step of developing with a developer containing a to form a toner image, and a transfer step of transferring the toner image to a base material such as paper,
The method includes a fixing step of fixing the toner image transferred to the base material, and a cleaning step of removing toner remaining on the photosensitive layer after the transfer step. 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. A so-called organic electrophotographic photoreceptor using various organic substances instead of these inorganic substances has been proposed. Such an organic electrophotographic photoreceptor has a photosensitive layer including a charge generating material that generates a charge by exposure and a charge transporting 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 the charge generation material and the charge transport material.

As the charge transporting material, various organic compounds have been proposed, for example, as disclosed in Japanese Patent Application Laid-Open No. 57-67940.

[0005]

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(Wherein R ₁ , R ₂ , R ₃ and R ₄ represent the groups described in the above publication), and the compound represented by the general formula: And an electrophotographic photoreceptor having excellent carrier transportability. Also, disclosed in Japanese Patent Application Laid-Open No. 61-228451,

[0007]

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(Wherein R ₁ , R ₂ , R ₃ and Ar ₂ represent the groups described in the above-mentioned publications).

[0009]

However, the electrophotographic photoreceptor using the compound described in the above publication has a drawback that the sensitivity, charging ability, residual potential and repetition characteristics are not sufficient. An object of the present invention is to solve such technical problems and to provide an electrophotographic photoreceptor excellent in sensitivity, charging ability and residual potential and having high repetition characteristics.

[0010]

In order to achieve the above object, the electrophotographic photoreceptor of the present invention has a general formula (1) on a conductive substrate.

[0011]

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Wherein Ar ¹ , Ar ² , Ar ³ and A
r ⁴ is the same or different and represents a hydrogen atom, an aryl group, an aralkyl group or a heterocyclic group, and any of the aryl group, the aralkyl group and the heterocyclic group may have a substituent; provided that Ar ³ and Ar ⁴ must not be hydrogen atoms at the same time; Ar ⁵ and Ar ⁶ may be the same or different and represent an alkyl group, an aryl group, an aralkyl group or a heterocyclic group; May have a substituent, or may form a ring together with the nitrogen atom to which it is bonded. An electrophotographic photosensitive member comprising a photosensitive layer containing a hydrazone compound represented by the formula (1).

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

As the aryl group, for example, a phenyl group,
Examples include a naphthyl group, a biphenylyl group, an anthryl group and a phenanthryl group. 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.

The heterocyclic group includes, for example, 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 , A pyridyl group, a piperidyl group, a piperidino group, a 3-morpholinyl group, and a morpholino group.

The substituents which may be substituted on the above groups include, for example, an amino group which may have a substituent such as a halogen atom or an alkyl, a hydroxyl group, a carboxyl group which may be esterified, a cyano group, Examples thereof include a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkoxy group, and a C ₂ -C ₆ alkenyl group which may have an aryl group. The substituent may be two or more, and two substituents may form a ring.

Ar ⁵ and Ar ⁶ may form a ring together with the nitrogen atom to which they are bonded. Examples of such a ring include pyrrole, 2H-pyrrole, 2-dipyrroline,
Piperidine, pyrrolidine, oxazole, isoxazole, thiazole, isothiazole, imidazole,
H-imidazole, 2-imidazoline, imidazolidin, pyrazole, triazole, tetrazole, pyridine, pyrimidine, pyrazine, piperazine and the like.

Specific examples of the hydrazone compound represented by the general formula (1) include the following.

[0019]

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[0020]

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[0021]

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[0022]

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[0023]

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The electrophotographic photoreceptor of the present invention comprises one or two of the hydrazone compounds represented by the general formula (1).
Contains more than one species. The compound represented by the formula (7) can be produced, for example, by the following reaction formula. Reaction formula:

[0025]

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That is, the compound represented by the formula (a) is sulfonated in the presence of sulfuric acid to obtain an intermediate represented by the formula (b), and this intermediate is converted to a hydrazone compound (c) and formaldehyde ( d) to give a compound of formula (e). Then, the intermediate of this formula (e) is referred to as Y. Sprinzak J.
Obtaining Am.Chem.Soc 80 .5449 (1958) was carbonylated according to the method shown in carbonyl compounds represented by the formula (f). Then, the intermediate of formula (f) is subjected to Wittig reaction with the compound of formula (g) to obtain the compound of formula (7) contained in the electrophotographic photoreceptor of the present invention. .

The photosensitive layer according to the present invention includes a single layer type in which a hydrazone compound represented by the above general formula (1), which is a charge generating material and a charge transporting material, and a binder resin are mixed. Although there is a laminated type in which a transport layer is laminated, the electrophotographic photoreceptor of the present invention can be applied to any of them. To obtain a laminated 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 the charge generation layer. What is necessary is just to form the charge transport layer containing a hydrazone compound. Alternatively, the charge generation layer may be provided on the charge transport layer by reversing the stacking order.

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.

In addition, the above-mentioned general formula (1) which is a charge transport material
The hydrazone compound represented by can be used in combination with other conventionally known charge transport materials. Conventionally known charge transporting materials include, for example, oxadiazole compounds such as 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole, 9- (4-diethylaminostyryl) anthracene, and the like. Styryl compounds,
Carbazole compounds such as polyvinyl carbazole, 1
Pyrazoline compounds such as -phenyl-3- (p-dimethylaminophenyl) pyrazole, triphenylamine compounds, indole compounds, oxazole compounds,
Examples include nitrogen-containing cyclic compounds such as isoxazole-based compounds, thiazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, pyrazole-based compounds, and triazole-based compounds, and condensed polycyclic compounds. 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 resin, polyurethane resin, Thermoplastic resins such as polycarbonate resin, polyarylate resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, silicone resin, epoxy resin, other crosslinkable thermosetting resins, and epoxy acrylate resin Urethane - like photocurable resin such as acrylate resin. 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 liquid 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.

Further, 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 photosensitive layer, the charge generation material and the binder resin constituting the charge generation layer can be used in various ratios, but the charge generation material is used for 100 parts (weight part, the same applies hereinafter) of the binder resin. 5 to 500 parts of material, especially 10
It is preferably used in a proportion of up to 250 parts.

The charge generation layer may have an appropriate thickness, but is preferably 0.01 to 5 μm, particularly 0.1 to 3 μm.
m. The hydrazone-based compound (charge transport material) represented by the above general formula (1) and the binder resin constituting the charge transport layer can be used in various ratios. To 100 parts of the binder resin so that the
The hydrazone compound represented by the general formula (1) is
It is preferable to use 500 parts, especially 25 to 200 parts.

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 photosensitive layer, 2 to 20 parts, particularly 3 to 15 parts, of the charge generating material is used per 100 parts of the binder resin,
The amount of the hydrazone-based compound (charge transport material) represented by (1) is suitably from 40 to 200 parts, particularly preferably from 50 to 150 parts. The thickness of the single-layer type photosensitive layer is 10 to 50 μm.
m, particularly preferably about 15 to 30 μm.

When the photoreceptor including the charge generation layer and the charge transport layer is formed by a coating means, the charge generation material or the charge transport material and the binder resin are mixed with 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.

[0038]

The present invention will be described below in detail with reference to examples and comparative examples. Examples 1 to 5 and Comparative Examples 1 and 2 (laminated photosensitive layer) 2 parts of charge generating material, 1 part of polyvinyl butyral resin, 120 parts of tetrahydrofuran were mixed with zirconia beads (2 mm diameter).
And dispersed for 2 hours with a paint shaker. 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 Table 1. In these Tables 1, the charge generating materials A, B and C mean compounds represented by the following formulas (A), (B) and (C), respectively.

[0039]

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A solution prepared by dissolving 1 part of a charge transport material and 1 part of a polycarbonate resin in 9 parts of toluene was applied on the charge generation layer by 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 Comparative Examples 1 and 2 are represented by the numbers of the compounds shown in the specific examples of the aforementioned general formula (1). ),
(II).

[0041]

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The formula (I) is based on the above-mentioned JP-A-57-67940.
In the publication, formula (II) is a compound disclosed in JP-A-61-228451. Examples 6 to 8 and Comparative Examples 3 and 4 (single-layer type photosensitive layer) 1 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 having a solid content of 20% by weight and 10 parts of a charge transport material were added, and the dispersion was further continued for 1 hour. The obtained dispersion was applied on an aluminum sheet using a wire bar, and dried at 100 ° C. for 1 hour to obtain a photoconductor of 20 μm. The charge generation materials and charge transport materials used are shown in Table 2 by the numbers assigned to the respective chemical structural formulas in the same manner as in Table 1 described above.

[Evaluation Test] The surface potential, residual potential and half-exposure (E _1/2 ) of the photoreceptor obtained in each of Examples and Comparative Examples were evaluated using an evaluation tester (“EPA81” manufactured by Kawaguchi Electric Co., Ltd.).
00 ”). The measurement conditions are as follows.
Light intensity: 50 lux Exposure intensity: 1/15 second Surface potential:
The flowing current value 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. Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1, and Examples 6 to 8 and Comparative Examples 3 and 4 are shown in Table 2.

[0045]

[Table 1]

[0046]

[Table 2]

From these test results, the photoreceptors of the respective examples have almost no difference in surface potential from the conventional photoreceptors (Comparative Examples 1 to 4), but the residual potential and half-exposure (E).
_1/2 ), indicating that the sensitivity was significantly improved.

[0048]

As described above, according to the electrophotographic photoreceptor of the present invention, since a hydrazone compound having excellent charge transporting ability is used as a charge transporting material, it is excellent in charging ability, sensitivity and residual potential. This has the effect of having high repetition characteristics.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 5/06 322 C07C 251/86

Claims (1)

(57) [Claims] 1. A method according to claim 1, wherein the conductive substrate has the general formula (1): (Wherein, Ar ¹ , Ar ² , Ar ³ and Ar ⁴ are the same or different and each represent a hydrogen atom, an aryl group, an aralkyl group or a heterocyclic group, and each of the aryl group, aralkyl group or heterocyclic group represents a substituent. May have; provided that A
r ³ and Ar ⁴ must not be simultaneously hydrogen atoms; Ar ⁵ and Ar ⁶ may be the same or different and represent an alkyl group, an aryl group, an aralkyl group or a heterocyclic group;
Each of the alkyl group, the aryl group, the aralkyl group, and the heterocyclic group may have a substituent, or may form a ring together with the nitrogen atom to which it is bonded. An electrophotographic photosensitive member comprising a photosensitive layer containing a hydrazone compound represented by the formula (1).