JPH06161124A - Photosensitive body for electrophotography - Google Patents

Abstract

PURPOSE:To provide a photosensitive body for electrophotography which is excellent in the characteristics of repetition by containing a specific azulene series compound into a photosensitive layer. CONSTITUTION:This photosensitive body for electrophotography is provided with a photosensitive layer including at least an electric charge generating material and an electric charge transporting material on a conductive base, and the photosensitive layer contains an azulene series compound expressed by a formula (R1, R2, R3, R4, R5, R6, R7 and R8 respectively represent hydrogen atoms, halogen atoms, a hydroxyl group, an alkyl group, an aryl group, an amino group and an aralkyl group, where the alkyl group, the aryl group, the amino group and the aralkyl group may include a substituent).

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 used in an image forming apparatus using an electrophotographic method such as an electrostatic copying machine and a laser beam printer.

[0002]

BACKGROUND OF THE INVENTION Problems to be Solved by the Invention The electrophotographic method such as the Carlson process is
A step of uniformly charging the surface of the electrophotographic photosensitive member, an exposure step of exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image on the surface, and developing the formed electrostatic latent image. When the agent is brought into contact with the toner contained in this developer,
A developing process that visualizes the electrostatic latent image into a toner image, a transfer process that transfers the toner image to paper, a fixing process that fixes the transferred toner image, and a residual toner on the photoconductor after the transferring process. And a cleaning step for removing the toner.

Organic photoconductors (OPC), amorphous silicon (α-Si), some selenium photoconductors, etc. are known as the electrophotographic photoconductors used in the electrophotographic method, but they are not designed to function. OPCs are often used in this field from the viewpoints of total flexibility, workability, and cost.
Such an organophotoreceptor usually has a photosensitive layer containing a charge generating material that generates a charge upon exposure and a charge transporting material that has a function of transporting the generated charge.

The above-mentioned organic photoreceptor is exposed to ozone and nitrogen oxides (NOx) generated by corona discharge in the charging step and light in the exposing step by repeated use in a copying machine. At this time, the charge generation material and the charge transport material in the organic photoreceptor are ozone, N
A chemical reaction occurs due to Ox and light, and the charge generation ability and charge transport ability are lost, and the substance becomes a deep trap that inhibits electrophotographic characteristics, resulting in a decrease in charging property, an increase in residual potential, and deterioration in sensitivity. The photoconductor is deteriorated.

On the other hand, in terms of equipment, ozone and NO
There is a drawback in that a special charging system that does not generate x, a system that decomposes generated ozone, a system that exhausts ozone in the apparatus, and the like are required, and the process and system are complicated. Further, regarding the prescription of the photoreceptor, JP-A-57-122444 and JP-A-61-161
As disclosed in Japanese Patent No. 156052, a proposal has been made to prevent oxidative deterioration of the above materials by adding an antioxidant, but the present situation is that satisfactory results have not yet been obtained.

The present invention is to solve the above-mentioned conventional problems and to provide an electrophotographic photoreceptor having excellent repetitive characteristics.

[0007]

In an electrophotographic photoreceptor having a photosensitive layer containing at least a charge generating material and a charge transporting material provided on a conductive substrate, the following general formula (1):

[0008]

[Chemical 2]

(Wherein R1, R2, R3, R4, R5, R
6, R7 and R8 are a hydrogen atom, a halogen atom, a hydroxyl group,
An alkyl group, an aryl group, an amino group and an aralkyl group are shown. However, the alkyl group, the aryl group, the amino group and the aralkyl group may have a substituent. The inventors have found that it is sufficient to provide a photosensitive layer containing an azulene compound represented by (4), and have completed the present invention.

Although the effect of the addition of the azulene compound of the present invention has not been clarified, the azulene compound of the present invention has no interaction with other photoconductor materials such as charge generating materials and charge transporting materials. It is a small compound that does not adversely affect the electrophotographic properties, has the action of deactivating radical species (which causes charge trapping) generated in the photosensitive layer by external attacking substances such as light and ozone. It is inferred that the ability to prevent the occurrence of is excellent. This is because by adding an azulene compound from the results of the examples described below, the amount of decrease in surface potential after 10,000 times of repetition is suppressed, and the deterioration in sensitivity indicated by half-exposure is small, It can be seen that it is effective in improving durability.

[0011]

[Preferable Embodiment] Additive In the azulene compound represented by the general formula (1), the alkyl group corresponding to R1 to R8 is, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group or an isobutyl group. , T-butyl group, pentyl group, hexyl group and the like.

As the aryl group, for example, a phenyl group,
Examples thereof include a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group and a phenanthryl group. Examples of the aralkyl group include a benzyl group, a benzhydryl group, a trityl group and a phenethyl group. The alkyl group, aryl group, amino group and aralkyl group may each have a substituent, and examples of the substituent include an alkyl group, a halogen atom, an alkoxy group, a hydroxyl group and an amino group.

Specific examples of the compound represented by the general formula (1) include No. 1 to No. 10 shown in Table 1 below.
The items shown in are listed.

[0014]

[Table 1]

In addition to the azulene-based compound, the organic photosensitive layer may further contain a sensitizer, a fluorene-based compound, an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, and an additive such as a plasticizer. . Further, in order to improve the sensitivity of the charge generation layer, for example, terphenyl, halonaphthoquinones,
Known sensitizers such as acenaphthylene may be used in combination with the charge generating material. Charge generation material As the charge generation material, a conventionally known charge generation material can be used, and selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salt, azo pigments, perylene pigments, ansanthuron pigments, Examples thereof include phthalocyanine pigments, indigo pigments, triphenylmethane pigments, slene pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments, and pyrrolopyrrole pigments. These charge generating materials may be used alone or
You may use more than one kind. Charge Transport Material As the charge transport material, various conventionally known electron withdrawing compounds and electron donating compounds can be used.

Examples of the electron-withdrawing compound include 2,
^{6-dimethyl-2,, 6,} - di tert- dibutyl phenoxide diphenoquinone derivatives non like, malononitrile, thiopyran compounds, tetracyanoethylene, 2,
4,8-trinitrothioxanthone, 3,4,5,7-
Tetranitro-9-fluorenone, dinitrobenzene,
Examples include 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, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds,
Examples thereof include nitrogen-containing cyclic compounds such as imidazole compounds, pyrazole compounds, and triazole compounds, and condensed polycyclic compounds.

These charge transport materials are 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. Binder Resin Various resins can be used as the binder resin. For example, styrene-based polymer, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, poly Thermoplastic resins such as vinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, polyester resin, etc. , Silicone resin, epoxy resin,
Examples thereof include phenol resins, urea resins, melamine resins, other crosslinkable thermosetting resins, and photocurable resins such as epoxy acrylate and urethane-acrylate.
These binder resins can be used alone or in combination of two or more. As the conductive substrate on which the organic photosensitive layer is formed, various conductive materials can be used, such as aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium and titanium. , Single metal such as nickel, palladium, indium, stainless steel, brass,
Examples include a plastic material obtained by vapor deposition or laminating of the above metal, glass coated with aluminum iodide, tin oxide, indium oxide, or 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, it is preferable that the conductive substrate has sufficient mechanical strength when used. Structure of Photoreceptor The photoconductor of the present invention can be applied to either a single layer type or a laminated type as a photosensitive layer. However, since the effect of the combination of the charge generating material and the charge transporting material becomes more remarkable especially in the single layer type photosensitive layer in which both materials are contained in the same layer, the present invention provides a single layer type photosensitive layer. It can be said that it is more preferable to apply to an electrophotographic photosensitive member having a layer.

To obtain a single-layer type photoreceptor, a photosensitive layer containing a charge generating material, a charge transporting material, the azulene compound of the present invention, a binder resin and the like is electrically conductive by means of coating or the like. It may be formed on the flexible substrate. Further, in order to obtain a laminated type photoreceptor, a charge generation layer containing the charge generation material is formed on a conductive substrate by means such as vapor deposition or coating,
A charge transport layer containing the charge transport material and a binder resin may be formed on the charge generation layer. Alternatively, conversely to the above, the charge transport layer may be formed on the conductive substrate, and then the charge generation layer may be formed.

The azulene compound of the present invention can be contained in the above charge generation layer and / or charge transport layer. In the laminated photoreceptor, the charge generating material and the binder resin that form the charge generating layer can be used in various proportions, but the charge generating material can be used with respect to 100 parts (weight part, hereinafter the same) of the binder resin. It is preferable to use 5 to 1000 parts, especially 30 to 500 parts of the material.

The charge-transporting material constituting the charge-transporting layer and the binder resin can be used in various proportions within a range that does not hinder the transport of charge and a range that does not crystallize. The charge transport material is preferably used in a ratio of 10 to 500 parts, particularly 25 to 200 parts, based on 100 parts of the binder resin so that the charges generated in the layer can be easily transported.

The thickness of the laminated photosensitive layer is preferably 0.01 to 5 μm, particularly 0.1 to 3 μm for the charge generation layer, and 2 to 100 μm for the charge transport layer.
m, particularly preferably about 5 to 50 μm.
In a single-layer type photoreceptor, the charge generation material is 0.1 to 50 parts, particularly 0.5 to 30 parts, relative to 100 parts of the binder resin,
Suitably the charge transport material is 20 to 200 parts, especially 30 to 150 parts. The thickness of the single-layer type photosensitive layer is 5
The thickness is preferably about 100 to 100 μm, particularly about 10 to 50 μm.

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

The azulene compound of the present invention is added in an amount of 0.25 to 50 parts per 100 parts of the binder resin in the layer to be added in both single-layer type photoreceptors and laminated type photoreceptors. Is preferred. If the addition amount is 0.25 part or less, the effect of addition is not sufficient, and if it exceeds 50 parts, the film strength of the photosensitive layer is lowered and the durability is lowered. Preparation of Photoreceptor When forming each of the above layers by a coating method, the charge generation material, charge transport material, binder resin and the like exemplified above, together with a suitable solvent, in a known method, for example, a roll mill,
Prepare a coating solution by dispersing and mixing with a ball mill, attritor, paint shaker or ultrasonic disperser.
This may be applied and dried by a known means.

As the solvent for forming the coating solution, 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, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, dimethyl ether, diethyl ether and tetrahydrofuran. Examples include ethers such as 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, dimethylformaldehyde, dimethylformamide and dimethyl sulfoxide. These solvents can be used alone or in combination of two or more.

Further, in order to improve the dispersibility of the charge transport material or the charge generating material and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent, etc. may be used. Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. Examples 1 to 12 and Comparative Examples 1 to 7 (lamination
Type photoconductor) 1 part by weight of the charge generating material and 19 parts by weight of cyclohexanone were dispersed for 4 hours with a paint shaker. Further, 5 parts by weight of 10 parts by weight of vinyl chloride-vinyl acetate copolymer dissolved in 40 parts by weight of cyclohexane was added, and the dispersion was continued for 1 hour. The obtained dispersion liquid was applied to an aluminum sheet with a wire bar and dried to form a charge generation layer having a film thickness of 0.7 μm.

On the charge generation layer, a solution of a composition for charge transport layer having the following composition was coated on a wire bar,
A charge transport layer was formed by drying at 100 ° C. for 1 hour to obtain a negatively chargeable laminated electrophotographic photoreceptor having a film thickness of 25 μm. (Component) (Parts by Weight) Charge Transport Material 100 Azulene Compound The Addition Amount is Disclosed in Table 2 Bisphenol A Polycarbonate 100 Dichloromethane 700 The charge generation material and charge transport material used are specifically shown below. Charge generation material

[0029]

[Chemical 3]

[0030]

[Chemical 4]

[0031]

[Chemical 5]

[0032]

[Chemical 6]

Charge Transport Material

[0034]

[Chemical 7]

[0035]

[Chemical 8]

The charge-generating materials, charge-transporting materials, and azulene compounds used as additives in each of the above Examples and Comparative Examples are shown in Table 2 by using the above-mentioned compound numbers.

[0037]

[Table 2]

Examples 13 to 24 and Comparative Example 8 to
Comparative Example 14 (single layer type photoreceptor) 4 parts by weight of charge generating material, 100 parts by weight of charge transporting material, azulene compound (addition amount is specifically disclosed in Table 3)
Then, 100 parts by weight of bisphenol A polycarbonate and 700 parts by weight of dichloromethane were dispersed in a paint shaker for 4 hours to prepare a coating liquid for a single layer type photosensitive layer.
Then, this coating solution was applied onto an aluminum sheet using a wire bar and dried at 100 ° C. for 1 hour to give a film thickness of 2
A positive charging type single-layer type electrophotographic photoreceptor having a thickness of 5 μm was obtained.

The charge-generating materials, charge-transporting materials, and azulene compounds as additives used in the above Examples and Comparative Examples are shown in Table 3 by using the above-mentioned compound numbers.

[0040]

[Table 3]

The following tests were conducted on the electrophotographic photoreceptors of the above-mentioned respective examples and comparative examples, and the characteristics thereof were evaluated. Electric characteristics By adjusting the flow-in current value by an electrostatic copying tester (Gentec Cynthia 30M manufactured by Gentec), the surface of the sheet-shaped electrophotographic photosensitive member prepared in Examples and Comparative Examples is adjusted to about ± 800V. After measuring the initial surface potential (V) at the time of charging, the most necessary 55 for the photoconductor for PPC.
The half-exposure amount was measured using 0 nm light. That is,
550n taken out from the xenon lamp using a spectrometer
m light was exposed with an intensity of 0.2 mW / cm ² and an exposure time of 1 second to obtain a half-exposure amount (μJ / cm ² ). Further, the surface potential at the time point when 0.5 seconds passed immediately after the exposure was determined as the post-exposure potential (V). Repetitive characteristics The electrophotographic photoreceptors obtained in each of the above Examples and Comparative Examples,
After sticking on each of the aluminum cylinders using an adhesive tape, they were mounted on an electrostatic copying machine DC-1670M (manufactured by Mita Industry Co., Ltd.).

Next, copying was repeated 10,000 times, and the electrophotographic photosensitive member was peeled from the aluminum cylinder at the initial stage and after repeating 10,000 times, and the surface potential (V), half-exposure amount (μJ / cm ² ), The post-exposure potential (V) was measured in the same manner as above. (However, the flow-in current value was the same as the initial value and after repeating 10,000 times.) The above results are shown in Tables 4 and 5.

[0043]

[Table 4]

[0044]

[Table 5]

As is clear from Tables 4 and 5, the electrophotographic photosensitive member of the present invention was excellent in charging property, post-exposure potential, half-exposure amount and repetitive property. On the other hand, the electrophotographic photosensitive member of the comparative example containing no azulene-based compound was extremely inferior in charging characteristics by repeated use, and the half-exposure amount was deteriorated.

[0046]

According to the present invention, by containing the compound represented by the general formula (1) as an additive, it is possible to provide an organic photoreceptor having excellent repeating characteristics.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hiroaki Sakai 1-2-2 Tamatsukuri, Chuo-ku, Osaka City, Osaka Prefecture Mita Kogyo Co., Ltd. No. 28 Mita Industry Co., Ltd.

Claims (1)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer containing at least a charge generating material and a charge transporting material, wherein the following general formula (1): (In the formula, R1, R2, R3, R4, R5, R6, R7, R
8 is a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group,
An aryl group, an amino group and an aralkyl group are shown. However, the alkyl group, the aryl group, the amino group and the aralkyl group may have a substituent. ) An electrophotographic photoreceptor provided with a photosensitive layer containing an azulene compound represented by the formula (1).