JPH0592937A - Quinone compound and photosensitizer using the same - Google Patents

Abstract

PURPOSE:To provide a quinone compound having a high carriertransferring ability, having excellent compatibility with binding resins composing photosensitizers, suitably used as an electric charge transferring material because of its having a low sublimating property, and capable of giving the highly sensitive photosensitizers. CONSTITUTION:A quinone compound of formula I (R<1>-R<10> are H, halogen, NO., CN, alkyl, alkoxy, aryl, halogen-substituted alkyl), e.g. a compound of formula 2. The compound can be produced by reacting a compound of formula (a) with a compound of formula (b) in the presence of an oxidizing agent in an organic solvent. The compound has a high carrier-transferring ability because of its having a wide conjugation system in comparison with conventional diphenoquinone compounds, and has a low sublimating property because of its having a large mol.wt. The compound having the halogen-substituted alkyl has especially a low sublimation property. Thereby, Photosensitizers having pho tosensitizing layers containing the compound and formed on conductive substrates have small residual potentials and excellent sensitivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quinone compound suitable as a charge transport material in a photoconductor and a photoconductor using the same.

[0002]

2. Description of the Related Art In recent years, organic photoconductors are widely used as photoconductors in image forming apparatuses such as copying machines because they are excellent in processability and economy and have a high degree of freedom in functional design. The Carlson process is widely used to form a copied image using a photoconductor. The Carlson process consists of a charging process that uniformly charges the photoconductor by corona discharge, an exposure process that exposes the document image on the charged photoconductor to form an electrostatic latent image corresponding to the document image, and an electrostatic latent image. After development with a developer containing toner, a developing step of forming a toner image, a transfer step of transferring the toner image to paper, a fixing step of fixing the transferred toner image, and a transfer step,
And a cleaning step for removing the toner remaining on the photoconductor. In order to form a high-quality image in the Carlson process, the photoconductor is required to have excellent charging properties and photosensitivity, and to have a low residual potential after exposure.

Conventionally, inorganic photoconductors such as selenium and cadmium sulfide have been known as photosensitive materials, but they have the drawbacks of toxicity and high production cost. Therefore, so-called organic photoconductors using various organic substances in place of these inorganic substances have been proposed. Such an organophotoreceptor has a photosensitive layer composed of a charge generating material that generates a charge upon exposure and a charge transporting material that has a function of transporting the generated charge.

In order to satisfy various conditions desired for such an organic photoreceptor, it is necessary to appropriately select these charge generating material and charge transporting material. As a charge transport material, various organic compounds have been studied so far.
Polyvinylcarbazole, oxadiazole-based compound,
Many substances such as pyrazoline compounds and hydrazone compounds have been proposed. Since these charge-transporting materials are hole-transporting materials, the function-separated type photoreceptor, which is currently the mainstream of organic photoreceptors, inevitably requires a negative charging process. However, the negative corona discharge is inherently unstable, and there are problems such as deterioration of the photoconductor due to generation of ozone and pollution of the use environment. In order to solve these problems, it is sufficient to adopt an organic photoreceptor that operates by positive charging using an electron transport material as the charge transport material,
As the electron transport material, for example, JP-A-1-206349 is available.
The compound having a diphenoquinone structure represented by the following general formula (20) described in the publication is excellent in electron transport performance. This compound is an electron acceptor having a delocalized π electron system, and can transport electrons by an electron transfer reaction involving an anion radical state.

[0005]

[Chemical 3]

(Wherein Ar ¹ , Ar ² , Ar ³ and A
r ⁴ , Ar ⁵ , Ar ⁶ , Ar ⁷ and Ar ⁸ each represent the substituents R ^{1 to} R ⁸ described in the above publication. )

[0007]

However, the diphenoquinone-based compound has a low compatibility with the binder resin constituting the photoconductor and a large amount of the diphenoquinone-based compound, for example, in the constitution of the substituent represented by the following formula (B): Since the compound cannot be contained in the photoconductor, when the diphenoquinone compound is used, there is a problem that the sensitivity is insufficient and only a photoconductor having a high residual potential can be obtained.

[0008]

[Chemical 4]

Further, since the diphenoquinone compound represented by the above general formula (20) has a sublimation property, the sensitivity may be lowered with time. That is, the characteristics of the diphenoquinone-based compound are greatly influenced by the substitution position of the substituent and its type. It is an object of the present invention to solve such technical problems and provide a highly sensitive photoconductor.

[0010]

Means and Actions for Solving the Problems The quinone compound of the present invention has the following general formula (1):

[0011]

[Chemical 5]

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ ,
R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are the same or different and each represents a hydrogen atom, a nitro group, a cyano group, a halogen atom, an alkyl group, an alkoxy group, an aryl group or a halogen-substituted alkyl group. ) Is represented by. The photoreceptor of the present invention for achieving the above object is characterized by having a photosensitive layer containing a quinone compound represented by the general formula (1) on a conductive substrate.

The quinone-based compound of the present invention has a wide carrier system as compared with the conventional diphenoquinone-based compound and thus has a high carrier transport ability. Further, since this quinone compound has an asymmetric structure, it has excellent compatibility with the resin. Furthermore, since the molecular weight is larger than that of the diphenoquinone compound, the sublimation property is low. Also,
Those having a halogen-substituted alkyl group as a substituent,
Especially low sublimation.

The alkyl group is, for example, a straight chain having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group and hexyl group. Examples include branched lower alkyl groups. As the alkoxy group, for example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a t-butoxy group, a pentyloxy group, a hexyloxy group, or the like having a carbon number of 1 to 6 is directly present. Examples include chained or branched alkoxy groups.

As the aryl group, for example, a phenyl group,
Examples thereof include biphenyl group, naphthyl group, anthryl group and phenanthryl group. As a halogen atom, fluorine,
Examples include chlorine, bromine, and iodine. Examples of the halogen-substituted alkyl group include a straight-chain or branched alkyl group having 1 to 6 carbon atoms substituted with 1 to 2 halogen atoms.

Specific examples of the quinone compound represented by the general formula (1) include those represented by the following formulas (11) to (12).

[0017]

[Chemical 6]

Of these, the quinone compound represented by the formula (12) has a trifluoromethyl group, which is a halogen-substituted alkyl group, as a substituent, and therefore has a particularly low sublimation property. The quinone compound of the present invention can be synthesized by various methods and can be obtained, for example, by the following reaction formula.

[0019]

[Chemical 7]

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ ,
R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are the same as above. ) In this reaction formula, a phenolic compound represented by the general formula (a) and a naphthol compound represented by the general formula (b) are dissolved in an organic solvent and reacted in the presence of an oxidizing agent. Thus, the quinone compound (1) of the present invention is obtained.

Examples of the organic solvent include chloroform,
Dichloromethane or the like can be used, and as the oxidizing agent, for example, potassium permanganate, potassium ferricyanide, or the like can be used. Further, this reaction is carried out at a temperature of about 50 to 55 ° C., and the amount of the oxidizing agent used is 1
The ratio is preferably 4 mol or more with respect to mol.

The photosensitive layer according to the present invention contains, as a charge transport material, one or more of the quinone compounds represented by the general formula (1). The photosensitive layer in the present invention includes a charge generating material and the above general formula (1) which is a charge transporting material.
A single layer type in which a compound represented by and a binder resin are mixed,
There is a laminated type in which a charge generation layer and a charge transport layer are laminated, but the photosensitive layer of the present invention is applicable to both.

In order to obtain a single-layer type photoreceptor, a photosensitive layer containing a compound represented by the general formula (1), which is a charge transport material, a charge generating material, a binder resin and the like is provided on a conductive substrate. It may be formed in. To obtain a laminated type photoreceptor, a charge generation layer containing a charge generation material is formed on a conductive substrate by means such as vapor deposition or coating, and a charge transport material is formed on the charge generation layer. A charge transport layer containing a compound represented by the general formula (1) and a binder resin may be formed. Alternatively, contrary to the above, a charge transport layer similar to the above may be formed on the conductive substrate, and then the charge generation layer containing the charge generation material may be formed by means such as vapor deposition or coating. Further, the charge generation layer may be formed by dispersing the charge generation material and the charge transport material in a binder resin and applying the dispersion.

As the charge generating material, conventionally used selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salt, azo compounds, disazo compounds, phthalocyanine compounds, anthanthrone compounds, perylene compounds. Examples thereof include compounds, indigo compounds, triphenylmethane compounds, slene compounds, toluidine compounds, pyrazoline compounds, perylene compounds, quinacridone compounds, and pyrrolopyrrole compounds. These charge generation materials can be used alone or in combination of two or more so that they have an absorption wavelength region in a desired region.

The quinone compound represented by the general formula (1), which is a charge transporting material, can be used alone or in combination with other conventionally known charge transporting materials. As the conventionally known charge transport material, various electron-withdrawing compounds and electron-donating compounds can be used. Examples of the electron-withdrawing compound include diphenoquinone derivatives such as 2,6-dimethyl-2 ′, 6′-ditert-dibutyldiphenoquinone, malononitrile, thiopyran compounds, tetracyanoethylene, 2,4,8- Examples include trinitrothioxanthone, 3,4,5,7-tetranitro-9-fluorenone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride and dibromomaleic anhydride. ..

The electron donating compound is 2,5
-Oxadiazole compounds such as di (4-methylaminophenyl) and 1,3,4-oxadiazole, 9- (4
-Styryl compounds such as diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, triphenylamine compounds, indole compounds Examples thereof include nitrogen-containing cyclic compounds such as compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and triazole compounds, and condensed polycyclic compounds.

These charge transport materials may be used alone or in combination of two or more. When a charge transporting material having film-forming property such as polyvinylcarbazole is used,
The binder resin is not always necessary. Various resins can be used as the binder resin in the photosensitive layer, charge generation layer and charge transport layer. For example, styrene polymer, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer,
Acrylic copolymer, 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, polysulfone, diallyl phthalate resin, ketone resin, polyvinylvinyl butyral resin, polyether resin and other thermoplastic resins, silicone resin, epoxy resin, phenol resin, urea resin, melamine resin and other crosslinkable heat Examples thereof include curable resins, and photocurable resins such as epoxy acrylate and urethane-acrylate. These binder resins may be used alone or in combination of two or more.

When the charge generating layer and the charge transporting layer are formed by the coating means, a solvent is used to prepare the coating solution. As this solvent, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane,
Benzene, toluene, aromatic hydrocarbons such as xylene, dichloromethane, dichloroethane, carbon tetrachloride, halogenated hydrocarbons such as chlorobenzene, dimethyl ether, diethyl ether, tetrahydrofuran, ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, Examples thereof include ketones such as cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide, dimethylsulfoxide and the like. These solvents may be used alone or in combination of two or more.

Further, in order to improve the sensitivity of the charge generating layer, known sensitizers such as terphenyl, halonaphthoquinones and acenaphthylene may be used together with the above charge generating material. Further, a surfactant, a leveling agent, etc. may be used in order to improve the dispersibility of the charge transporting material or the charge generating material and the dyeing property.

As the conductive substrate, various conductive materials can be used. For example, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium. Examples include simple metals such as stainless steel and brass, plastic materials obtained by vapor-depositing or laminating the above metals, and 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. Further, the conductive substrate is preferably one having sufficient mechanical strength when used. In the multi-layer type photoreceptor, the charge generating material and the binder resin which form the charge generating layer can be used in various ratios, but the charge can be changed with respect to 100 parts of the binder resin (weight part, the same applies hereinafter). 5 to 500 parts of generating material, especially 1
It is preferably used in a ratio of 0 to 250 parts. The charge generation layer may have an appropriate film thickness, but 0.01
The thickness is preferably about 5 to 5 μm, and more preferably about 0.1 to 3 μm.

The quinone compound (charge-transporting material) represented by the general formula (1) constituting the charge-transporting layer and the binder resin may be mixed in various amounts within a range that does not hinder the transport of charges and a range that does not crystallize. The quinone-based compound represented by the above general formula (1) can be used with respect to 100 parts of the binder resin so that the charge generated in the charge generation layer by light irradiation can be easily transported. 25-200 parts, especially 50-15
It is preferably used in a ratio of 0 part. Further, the charge transport layer is preferably formed to have a thickness of 2 to 100 μm, particularly 5 to 30 μm.

In the single-layer type photoreceptor, the binder resin 10
2 to 20 parts, especially 3 to 15 parts of charge generation material to 0 parts
The amount of the quinone compound (charge transport material) represented by the general formula (1) is 40 to 200 parts, and preferably 50 to 150 parts. The thickness of the single-layer type photosensitive layer is 10 to 10.
It is preferably 50 μm, particularly about 15 to 30 μm.

In the case of a single-layer type electrophotographic photosensitive member, it is between the conductive substrate and the photosensitive layer, and in the laminated type photosensitive member, it is between the conductive substrate and the charge generating layer. Alternatively, a barrier layer may be formed between the conductive substrate and the charge transport layer and between the charge generation layer and the charge transport layer to the extent that the characteristics of the photoreceptor are not impaired. A protective layer may be formed.

When the charge generating layer and the charge transporting layer are formed by a coating method, the charge generating material and the binder resin may be formed by a known method such as roll mill, ball mill, attritor, paint shaker or ultrasonic wave. A coating solution may be prepared by dispersing and mixing using a disperser or the like, and the coating solution may be coated and dried by a known means. As described above, the charge generation layer may be formed by depositing the above charge generation material.

[0036]

The present invention will be described in detail below with reference to Examples and Comparative Examples. Example 1 <Synthesis of quinone compound represented by the above formula (11)> 2, 6
-1.83 g (15 mmol) of dimethylphenol and 2
--Methyl-1-Naphthol 2.37 g (15 mmo
1) and were dissolved in 65 ml of chloroform, 19 g (120 mmol) of potassium permanganate was further added, and the mixture was stirred at 55 ° C. for 2 hours. After the insoluble matter was filtered off, the solvent was distilled off.

The obtained residue was divided into an ethanol-soluble portion and an ethanol-insoluble portion, the former was recrystallized from ethanol / chloroform, and purified by column chromatography.
A quinone compound represented by the formula (11) was obtained. The yield of this quinone compound was 0.72 g, and the yield was 17.4%. Moreover, the following results were obtained when the elemental analysis was performed.

Elemental analysis value: Calculated value (%) as C ₁₉ H ₁₆ O ₂ C82.58 H5.84 Measured value (%) C82.68 H5.93 Example 2 <Quinone represented by the above formula (12) Of 2-based compounds> 2-trifluoromethyl-1 in place of 2-methylnaphthol
-A quinone compound represented by the above formula (12) was obtained in the same manner as in Example 1 except that 3.18 g (15 mmol) of naphthol was used.

When the elemental analysis of this compound was performed, the following results were obtained. Elemental analysis value: C ₁₉ H ₁₃ O ₂ F ₃ Calculated value (%) C69.09 H3.97 Measured value (%) C69.22 H4.06 Examples 3 to 4 (multilayer photoreceptor) As charge generation material Metal-free phthalocyanine (X-type H ₂
1 part of Pc), 1 part of polyvinyl butyral resin (charge generating material: resin = 1: 1), and 120 parts of tetrahydrofuran were dispersed for 2 hours with a paint shaker using zirconia beads (2 mm diameter). The obtained dispersion liquid was applied onto an aluminum sheet using a wire bar, and 10
It was dried at 0 ° C. for 1 hour to obtain a 0.5 μm charge generation layer.

On this charge generating layer, 75 parts of the quinone compound obtained in Example 1 (Example 3) or Example 2 (Example 4) as a charge transport material, 100 parts of a polycarbonate resin (charge transport material) : Resin = 0.75: 1) dissolved in toluene and applied with a wire bar to give 100
The film was dried at 0 ° C. for 1 hour to form a charge transport layer having a thickness of 22 μm to obtain a laminated type photoreceptor.

Comparative Example 1 (Layered Photoreceptor) A laminated photoreceptor was obtained in the same manner as in Example 3 except that the compound represented by the above formula (B) was used as the charge transport material. Examples 5 to 6 (single-layer type photoreceptor) 1 part of metal-free phthalocyanine, 100 parts of polycarbonate resin, 500 parts of tetrahydrofuran, 4-methyl-m-phenylenediamine 50 as hole transport material
Example 1 (Example 5) as parts and charge transport material
Alternatively, the dispersion containing 40 parts of the quinone compound obtained in Example 2 (Example 6) is applied onto an aluminum sheet and dried to form a photosensitive layer having a film thickness of 20 μm, and a single layer type photosensitive layer is formed. Got the body

Comparative Example 2 (Single Layer Type Photoreceptor) A laminated type photoreceptor was obtained in the same manner as in Example 5 except that the compound represented by the above formula (B) was used as the charge transport material. (Evaluation Test) The surface potentials, residual potentials, and half-exposure amounts (E _1/2 ) of the photoconductors obtained in the respective examples and comparative examples were measured by “EPA8100” manufactured by Kawaguchi Electric Co., Ltd. Is a xenon lamp, 650 nm with a monochromator, 10 μW
The light of / cm ² was taken out and irradiated on the photoconductor.

The measurement conditions are as follows. Light: 650 nm, 10 μW / cm ² Dark decay: 1 sec Light decay: 10 sec Surface potential: (±) The inflow current value was adjusted to be near 700 V.

Measurement of residual potential: Measurement was started 5 seconds after the start of exposure. Table 1 shows the test results of the laminated photoreceptors (Examples 3 to 4 and Comparative Example 1), and Table 2 shows the test results of the single-layer photoreceptors (Examples 5 to 6 and Comparative Example 2).

[0045]

[Table 1]

[0046]

[Table 2]

From these test results, it is understood that the photoconductors of Examples 3 to 6 have a smaller residual potential and excellent sensitivity as compared with the photoconductors of Comparative Examples 1 and 2.

[0048]

INDUSTRIAL APPLICABILITY As described above, the quinone compound of the present invention is suitably used as a charge transporting material, and a highly sensitive photoreceptor can be obtained.

Claims (2)

[Claims] 1. The following general formula (1): (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ ,
R ⁸ , R ⁹ and R ¹⁰ are the same or different and each represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group,
An alkoxy group, an aryl group or a halogen-substituted alkyl group is shown. ) A quinone compound represented by. 2. A photoconductor comprising a conductive substrate and a photosensitive layer containing a quinone compound represented by the following general formula (1). [Chemical 2] (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ ,
R ⁸ , R ⁹ and R ¹⁰ are the same or different and each represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group,
An aryl group or a halogen-substituted alkyl group is shown. )