JPH0754405B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member that is preferably used in an image forming apparatus such as a copying machine.

(Prior Art) In recent years, as an electrophotographic photosensitive member in an image forming apparatus such as a copying machine, an organic photosensitive member has been used which has good processability and is advantageous in terms of manufacturing cost and has a large degree of freedom in functional design. Among them, a photosensitive layer containing a charge generating material that generates a charge by light irradiation and a charge transporting material that transports the generated charge, for example, a single layer type in which the charge generating material and the charge transporting material are contained in a binder resin. A function-separated electrophotographic photosensitive member has been proposed which includes a photosensitive layer and a laminated photosensitive layer in which a charge generating layer containing the above charge generating material and a charge transporting layer containing the above charge transporting material are laminated. .

When forming a copied image using an electrophotographic photosensitive member, the Carlson process includes a charging step of uniformly charging the photosensitive member by corona discharge, and exposing the charged photosensitive member with an original image to correspond to the original image. An exposure step of forming an electrostatic latent image, a developing step of developing the electrostatic latent image with a developer containing toner to form a toner image, and a transfer step of transferring the toner image to a substrate such as paper, The basic process includes a fixing process for fixing the toner image transferred to the base material and a cleaning process for removing the toner remaining on the photoconductor after the transfer process. In order to form, the electrophotographic photosensitive member is required to have excellent photosensitivity.

(Problems to be Solved by the Invention) However, in the above-mentioned function-separated electrophotographic photoreceptor, the characteristics of the materials used such as the charge generating material, the charge transporting material, and the additive are related to the electrical characteristics and the photosensitive characteristics of the photoreceptor. Despite the fact that various substances have been studied and proposed since they have a great influence, an organic photoconductor having sufficient photosensitivity has not been obtained yet. Therefore, an object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity by using a biphenyl derivative having excellent sensitizing action and repeating characteristics.

(Means and Action for Solving Problems) The present invention relates to the following formula [I] together with a charge transport material. The object was achieved by comprising an electrophotographic photoreceptor having a layer containing a biphenyl derivative represented by the formula (wherein R represents an aralkyl group) in a binder resin.

As a result of intensive studies, the present inventors have found that a biphenyl derivative is an extremely good additive.

(Preferred Embodiment of the Invention) An important feature of the present invention is to provide an electrophotographic photoreceptor having a layer containing a biphenyl derivative in a binder resin together with a charge transport material.

The biphenyl derivative used in the present invention has the following formula [I] (In the formula, R represents an aralkyl group), and the aralkyl group is at a side end portion of a lower alkyl group having 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and isobutyl. It has a benzene ring, and the benzene ring may have a substituent, and the substituent has 1 carbon atom such as methyl, ethyl, n-propyl, isopropyl, n-butyl and isobutyl. Examples thereof include lower alkyl groups of 4 to 4, halogen atoms such as fluorine, chlorine, bromine and iodine atoms, and lower alkoxyl groups such as methoxy and ethoxy groups.

Among them, parabenzyl biphenyl, in which R is a benzyl group having a benzene ring at the side end of the methyl group, is particularly preferable.

The compound represented by the above formula [I] can be applied to so-called single-layer type or multi-layer type electrophotographic photoreceptors as long as it is used together with the charge transport material.

In order to obtain a single-layer type electrophotographic photoreceptor, a biphenyl derivative represented by the above formula [I] as an additive, a charge generating material and a charge transporting material are contained in a binder resin to form a photosensitive layer as a conductive substrate. It may be formed on top.

In order to obtain a laminated type electrophotographic photoreceptor, a charge generation layer containing the above charge generation material is formed on a conductive substrate by means such as vapor deposition or coating, and the above formula [ [I] to form a charge transport layer containing a biphenyl derivative, a charge transport material and a binder resin, or conversely to the above structure, a charge transport layer similar to the above is formed on a conductive substrate. Then, a charge generating layer containing the charge generating material may be formed by means such as vapor deposition or coating.

The biphenyl derivative as the above-mentioned additive can be used in various proportions within a range that does not hinder charge transport, but the biphenyl derivative represented by the above formula [I] is added to 100 parts by weight of the binder resin. It is preferable to use 5 to 60 parts by weight, particularly 5 to 40 parts by weight. When the content of the biphenyl derivative with respect to 100 parts by weight of the binder resin is less than 5 parts by weight, the sensitizing effect and the repeating property are deteriorated, and when it exceeds 60 parts by weight,
The charging ability tends to decrease. In particular, when it is used within the range of 5 to 40 parts by weight, it is possible to obtain the electric characteristics excellent in the sensitizing effect, the repeating characteristics and the charging ability.

Regarding the photoreceptor using the above-mentioned biphenyl derivative in the present invention, as a basic constituent material such as a charge generating material, a charge transporting material and a binder resin, materials known per se can be appropriately used.

Examples of the charge generation material include selenium, selenium-tellurium, amorphous silicon, pyrylium salt, azo pigments, disazo pigments, anthanthrone pigments, phthalocyanine pigments, indigo pigments, triphenylmethane pigments, and slene pigments. , Toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments, etc., and they may be used singly or in combination of two or more so as to have an absorption wavelength region in a desired region.

Further, as the charge transport material, a nitro group, a nitroso group,
Electron-accepting substances such as cyano group, for example, tetracyanoethylene, fluorenone compounds such as 2,4,7-trinitro-9-fluorenone, dinitroanthracene, 2,4,8-
Nitrated compounds such as trinitrothioxanthone; electron-donating compounds such as N, N, N ', N'-tetrakis (3-
Tolyl) -1,3-phenylenediamine and other meta-phenylenediamine compounds, N, N-diethylaminobenzaldehyde N, N-diphenylhydrazone, N-methyl-3
-Carbazolylaldehyde N, N-diphenylhydrazones and other hydrazone compounds, oxadiazole compounds,
Nitrogen-containing cyclic compounds such as styryl compounds, pyrazoline compounds, oxazole compounds, isoxazole compounds, thiazole compounds, imidazole compounds, pyrazole compounds, indole compounds, driazole compounds, anthracenes, pyrenes, phenanthrenes, etc. Examples of the condensed polycyclic compound, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, ethylcarbazole-formaldehyde resin, and the like. The charge transport material may be used alone or in combination of two or more.

Further, as the binder resin in the photosensitive layer, the charge generation layer, and the charge transport layer, various resins can be used, and examples thereof include a styrene-based polymer, a styrene-butadiene copolymer, a styrene-acrylonitrile copolymer, Styrene
Maleic acid copolymer, acrylic polymer, styrene-acrylic copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, Thermoplastic resin such as alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallylphthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, silicone resin, urea resin, melanin resin, and other crosslinkable thermosetting resin Examples thereof include various polymers such as a photosensitive resin and a photocurable resin such as epoxy acrylate and urethane-acrylate. These binder resins may be used alone or in combination of two or more.

A solvent is used when the charge generation layer and the charge transport layer are formed by the coating means. As the solvent, various organic solvents can be used, alcohols such as methanol, ethanol, isopropanol and butanol, alcohols such as n-hexane, octane and cyclohexane,
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, tetrahydrofuran, Examples include ethers such as ethylene glycol dimethyl ether and ethylene glycol diethyl ether, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and methyl acetate, and various solvents such as dimethylformaldehyde and dimethyl sulfoxide. Used as a mixture of two or more species.

In addition, when an antioxidant is used in combination, it is possible to preferably prevent deterioration of a charge transport material having a structure susceptible to oxidation due to oxidation.

As the above-mentioned antioxidant, 2,6-di-tert-butyl-p
-Cresol, triethylene glycol- [3- (3-
tert-butyl-5-methyl-4-hydroxyphenyl)
Propionate], 1,6-hexanediol-bis [3
-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2 -Thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2-thiobis [4-methyl-6-tert-butylphenol), N, N'-hexa Methylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-
Examples thereof include phenolic antioxidants such as tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, and among them, 2,6-di-tert-butyl-p
-Cresol is preferred.

As the conductive substrate, various materials having conductivity can be used, and examples thereof include aluminum, copper, tin, platinum, gold,
Coated with silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless copper, brass metal simple substance, plastic material in which the above metal is vapor-deposited or laminated, aluminum iodide, tin oxide, indium oxide, etc. Illustrated are, for example, the formed glass. The conductive substrate may be in the shape of a sheath or a drum, and it is preferable that the substrate itself is conductive or the surface of the substrate is conductive and has sufficient mechanical strength when used.

In the multilayer photoreceptor, when the charge transport material is used together with the binder resin, the charge transport material and the binder resin can be used in various ratios.
It is preferable to use 10 to 500 parts by weight, especially 25 to 200 parts by weight of the charge transport material per 100 parts by weight. In addition, the charge transport layer containing the compound represented by the formula [I] is 2 to
The layer thickness is preferably 100 μm, particularly 5 to 30 μm.

When the charge generating material is used with the binder resin,
The charge generating material and the binder resin can be used in various ratios, but it is preferable to use 5 to 200 parts by weight, particularly 10 to 250 parts by weight of the charge generating material with respect to 100 parts by weight of the binder resin. preferable. The charge generation layer may have an appropriate layer thickness, but it is preferably formed to have a thickness of 0.01 to 3 μm, particularly 0.1 to 2 μm.

On the other hand, in the single-layer type electrophotographic photoreceptor, the charge generating material, the charge transporting material and the binder resin can be used in various proportions. Generating material 2 to 20 parts by weight, charge transport material 40 to 200
It is preferable to use parts by weight. Further, the photosensitive layer is 5 to
The layer thickness is preferably 60 μm, particularly about 10 to 30 μm.

In order to form each of the photosensitive layers by a coating means, each material such as the binder resin is adjusted by a conventionally known method, for example, a roll mill, a ball mill, an attritor, a paint shaker or an ultrasonic disperser. It may be applied and dried by a conventionally known applying means.

(Example) Hereinafter, the present invention will be described in more detail based on examples.

Example 1 100 parts by weight of poly- (4,4′-cyclohexylidenediphenyl) carbonate (trade name Polycarbonate Z, manufactured by Mitsubishi Gas Chemical Co., Inc.), N, N′-di (3,5-dimethylphenyl)
Perylene-3,4,9,10-tetracarboxydiimide 8 parts by weight, X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals, Inc.) 0.2 parts by weight, 3,3'-dimethyl-N, N, N ', N'- Tetrakis-4-methylphenyl (1,1'-biphenyl)-
80 parts by weight of 4,4'-diamine, 8 parabenzyl biphenyl
Parts by weight, antioxidant (manufactured by Kawaguchi Chemical Co., Ltd., trade name Antage)
BHT) 5 parts by weight, polydimethylsiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.01 parts by weight, and a predetermined amount of tetrahydrofuran,
A single layer type photosensitive layer dispersion liquid is prepared by mixing and dispersing with an ultrasonic disperser, and is applied on an alumite-treated aluminum base tube to form a photosensitive layer with a thickness of about 23 μm, and heat treated at about 100 ° C. By doing so, an electrophotographic photosensitive member was prepared.

Example 2 A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 20 parts by weight of parabenzyl biphenyl used in Example 1 was used in place of 8 parts by weight.

Example 3 A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 30 parts by weight of parabenzyl biphenyl used in Example 1 was used in place of 8 parts by weight.

Example 4 A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 40 parts by weight of parabenzyl biphenyl used in Example 1 was used in place of 8 parts by weight.

Example 5 A single-layer type electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 55 parts by weight of parabenzyl biphenyl used in Example 1 was used in place of 8 parts by weight.

Example 6 100 parts by weight of oxotitanyl phthalocyanine, 100 parts by weight of polyvinyl butyral (Denka Butyral # 500-A manufactured by Denki Kagaku Kogyo Co., Ltd.) and a predetermined tetrahydrofuran were used to prepare a charge generation layer coating solution. Is applied on the anodized aluminum tube,
A heat generation process was performed at 0 ° C. to form a charge generation layer having a thickness of about 0.2 μm. Then, 3,3'-dimethyl-N, N, N ',
100 parts by weight of N'-tetrakis-4-methylphenyl (1,1'-biphenyl) -4,4'-diamine, poly- (4,4'-
100 parts by weight of cyclohexylidene diphenyl) carbonate (trade name polycarbonate Z, manufactured by Mitsubishi Gas Chemical Co., Inc.),
A coating solution for charge transport consisting of 20 parts by weight of parabenzyl biphenyl and predetermined benzene was prepared, and the coating solution was applied on the charge generation layer and dried by heating to obtain a thickness of about
A 20 μm-thick charge transport layer was formed to prepare a laminated electrophotographic photoreceptor.

Comparative Example 1 A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the parabenzyl biphenyl used in Example 1 was not added.

Comparative Example 2 2,2 in place of the parabenzyl biphenyl used in Example 1
A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 20 parts by weight of -dichloro-1,4-naphthoquinone was used.

Comparative Example 3 2,2 in place of the parabenzyl biphenyl used in Example 6
A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 6 except that 20 parts by weight of -dichloro-1,4-naphthoquinone was used.

[Evaluation of electrophotographic photoreceptor]

The electrophotographic photoreceptors obtained in each of the above Examples and Comparative Examples were positively or negatively charged using a tram sensitivity tester (Gentec Co., Ltd., Gentec Cynthia 30M), and the photosensitivity was measured under the following conditions. And the surface potential were measured, and the results are shown in Table 1.

Exposure time: 60 msec Light source: Halogen lamp Exposure intensity: 0.92 mW In the table, V _sp (V) indicates the initial surface potential of the photoconductor when the photoconductor is charged under the above conditions, and E1 / 2 (ΜJ /
cm ² ) indicates the exposure dose required for the surface potential to become half of the initial surface potential V _sp (V). The surface potential after 0.4 seconds from the start of exposure was measured as the residual potential V _rp (V).
Further, the above electrophotographic photoconductors were mounted on an electrophotographic copying machine (manufactured by Mita Kogyo Co., Ltd., trade name DC-111), and the surface potential V _1500SP (V) and residual potential after repeating the electrophotographic process 1500 times. V _1500RP (V) was measured. In the table, ΔV _rp
(V) is a value calculated by the following formula V = V _rp (V) -V _{1500 RP} (V).

As is clear from Table 1, the electrophotographic photoreceptors of Examples 1 to 6 in which the biphenyl derivative was used in combination had a higher sensitivity than the electrophotographic photoreceptor of Comparative Example 1 containing no biphenyl derivative. It was high and the residual potential was low in the repeating characteristics. Further, the electrophotographic photoreceptors of Comparative Examples 2 to 3 using 2,3-dichloro-1,4-naphthoquinone as a sensitizer had extremely high residual potential in terms of repetitive characteristics.

(Effects of the Invention) The electrophotographic photosensitive member of the present invention is configured as described above, has a high sensitizing effect, and is excellent in the action of preventing the residual potential from rising when the image process is repeated.

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Claims (2)

[Claims] 1. A compound of the following formula [I] together with a triphenyldiamine compound. An electrophotographic photoreceptor having a layer containing a biphenyl derivative represented by the formula (wherein R represents an aralkyl group) in a binder resin. 2. The electrophotographic photosensitive member according to claim 1, wherein the biphenyl derivative is parabenzylphenyl.