JP2622752B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor in which a photosensitive layer contains a barbituric acid derivative or a thiobarbituric acid derivative having a specific structure. About the body.

[Prior Art] Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as electrophotographic photoreceptors.

On the other hand, as an electrophotographic photoreceptor using an organic photoconductive substance, a photoconductive polymer represented by poly-N-vinylcarbazole or 2,5-bis (p-diethylaminophenyl) -1,3,4- There are known those using a low-molecular organic photoconductive substance such as oxadiazole, and those combining such an organic photoconductive substance with various dyes and pigments.

An electrophotographic photoreceptor using an organic photoconductive substance has advantages in that it has good film-forming properties, can be produced by coating, and can provide an extremely high productivity and inexpensive photoreceptor. Further, there is an advantage that color sensitivity can be freely controlled by selecting a sensitizer such as a dye or a pigment to be used, and wide studies have been made so far. Particularly recently, with the development of a function-separated type photoreceptor in which a charge generation layer containing an organic photoconductive dye or pigment and a charge transport layer containing the above-mentioned photoconductive polymer or low molecular organic conductive material are laminated. Significant improvements have been made in sensitivity and durability, which have been disadvantages of conventional organic electrophotographic photosensitive members.

As such photoconductive materials, for example, azo pigments and barbituric acid derivatives or thiobarbituric acid derivatives described in JP-A-57-119355 are known.

However, electrophotographic photoreceptors using conventional disazo pigments, barbituric acid derivatives, and thiobarbituric acid derivatives are not sufficient in terms of sensitivity and potential stability during repeated use, and have been put to practical use. There are only a few materials.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel photoconductive material, and to provide an electrophotographic photoreceptor having practical high sensitivity characteristics and stable potential characteristics when repeatedly used. That is.

Means for Solving the Problems and Action The present invention relates to an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer has a barbituric acid derivative or a thiobarbituric acid derivative represented by the following general formula (1). And an electrophotographic photoreceptor characterized by containing

General formula In the formula, Y represents an oxygen atom or a sulfur atom, R ₁ represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may be bonded via a bonding group, and R ₂ and R ₃ represents a hydrogen atom, an optionally substituted alkyl group or an aryl group, m is an integer of 2 or 3, n is 1
Or an integer of 2.

Specifically, in the definition of R ₁ , as the bonding group, a group such as carbonyl, imino, and nitrile may be mentioned, and as the aromatic hydrocarbon group, a group such as naphthyl, phenanthryl, anthranyl, or pyrenyl, or an aromatic heterocyclic group pyridyl as, thienyl, carbazolyl, benzimidazolyl, benzothiazolyl, furyl, groups such as quinolyl mentioned, R _2, methyl as the alkyl group in the definition of R _3, groups such as ethyl, phenyl and the aryl group, naphthyl, Examples of substituents of the above groups include halogen atoms such as chlorine atom and bromine atom, alkyl groups such as methyl and ethyl, aryl groups such as phenyl, naphthyl and anthryl, and aralkyl such as benzyl and phenethyl. And the like.

Hereinafter, representative examples of the barbituric acid derivative and the thiobarbituric acid derivative represented by the general formula (1) used in the present invention are listed, but the material used in the present invention is not limited to these.

Compound example (1) Compound example (2) Compound example (3) Compound example (4) Compound example (5) Compound example (6) Compound example (7) The electrophotographic photoreceptor of the present invention comprises a conductive support containing a barbituric acid derivative represented by the general formula (1) or a thiobarbituric acid derivative (hereinafter abbreviated as a compound represented by the general formula (1)). With layers.

The form of the photosensitive layer may be any known form, but a photosensitive layer containing the compound represented by the general formula (1) is used as a charge generation layer, and a charge transport layer containing a charge transport substance is laminated on this. The function-separated type photosensitive layer described above is particularly preferable.

The charge generation layer can be formed by applying a coating solution obtained by dispersing the compound represented by the general formula (1) together with a binder resin in a suitable solvent onto a conductive support by a known method. The thickness is desirably a thin film layer having a thickness of, for example, 5 μm or less, preferably 0.1 to 1 μm.

The binder resin used at this time is selected from a wide range of insulating resins or organic photoconductive polymers, but polyvinyl butyral, polyvinyl benzal, polyarylate, polycarbonate, polyester, phenoxy resin, cellulose resin, acrylic resin, urethane Resins and the like are preferable, and the amount used is determined by the content in the charge generation layer.
It is at most 80% by weight, preferably at most 40% by weight.

The solvent used is preferably selected from those which dissolve the resin and do not dissolve the charge transport layer and the undercoat layer described below.

Specifically, tetrahydrofuran, ethers such as 1,4-dioxane, cyclohexane, ketones such as methyl ethyl ketone, amides such as N, N-dimethylformamide, methyl acetate, esters such as ethyl acetate,
Aromatic compounds such as toluene, xylene, and chlorobenzene; alcohols such as methanol, ethanol, and 2-propanol; and aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene. .

The charge transport layer is stacked on or below the charge generation layer, and has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting the charge carriers to the surface.

The charge transporting layer is formed by dissolving a charge transporting material in a solvent together with a suitable binder resin if necessary, and applying the solution. The thickness of the charge transporting layer is generally 5 to 40 μm.
-30 μm is preferred.

The charge transporting substance includes an electron transporting substance and a hole transporting substance. Examples of the electron transporting substance include 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, chloranil, and tetralane. Examples thereof include electron-withdrawing substances such as cyanoquinodimethane, and those obtained by polymerizing these electron-withdrawing substances.

Examples of the hole transporting substance include polycyclic aromatic compounds such as pyrene and anthracene, carbazole-based, indole-based, imidazole-based, oxazole-based, thiazole-based, oxadiazole-based, pyrazole-based, pyrazoline-based, thiadiazole-based, and triazole-based compounds. Heterocyclic compounds such as
Hydrazone compounds such as p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, N, N-diphenylhydrazone-3-methylidene-9-ethylcarbazole, α-phenyl-4′-N, N-diphenylaminostilbene, 5- A styryl-based compound such as [4- (di-p-tolylamino) benzylidene] -5H-dibenzo [a, b] cycloheptene, a benzidine-based compound, a triarylmethane-based compound, triphenylamine, or a group composed of these compounds. Polymers having a main chain or a side chain (for example, poly-N-vinylcarbazole, polyvinylanthracene, and the like) can be given.

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can be used.

These charge transport materials can be used alone or in combination of two or more.

When the charge transport material does not have a film-forming property, a suitable binder resin can be used.Specifically, acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile styrene copolymer, polyacrylamide, polyamide, Examples thereof include insulating resins such as chlorinated rubber and organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

As the conductive support, for example, a metal such as aluminum, an aluminum alloy, and stainless steel can be used.

Further, a support or conductive particles obtained by coating such a metal on a plastic or metal support with a plastic or conductive particles (eg, carbon black, silver particles, etc.) formed by coating with a suitable binder resin. And a support body impregnated with plastic or paper.

An undercoat layer having a barrier function and an adhesive function may be provided between the conductive support and the photosensitive layer.

The undercoat layer can be formed of casein, polyvinyl alcohol, nitrocellulose, polyamide (nylon 6, nylon 66, nylon 610, copolymer nylon, alkoxymethylated nylon, etc.), polyurethane, aluminum oxide, or the like.

The thickness of the undercoat layer is 5 μm or less, preferably 0.1 to 3 μm.
m is appropriate.

As another specific example of the present invention, an electrophotographic photosensitive member in which the compound represented by the general formula (1) and the charge transporting substance are contained in the same layer can be mentioned. At this time, a charge transfer complex composed of poly-N-vinylcarbazole and trinitrofluorenone can be used as the charge transport material.

The electrophotographic photoreceptor of this embodiment can be formed by applying and drying a liquid in which a compound represented by the general formula (1) and a charge transporting substance are dispersed in an appropriate resin solution.

The crystal form of the compound represented by the general formula (1) used in any of the electrophotographic photoreceptors may be amorphous or crystalline, and if necessary, the compound represented by the general formula (1) May be used in combination of two or more, or in combination with a known charge generating substance.

The electrophotographic photoreceptor of the present invention can be widely used not only for electrophotographic copying machines but also for electrophotographic applications such as laser beam printers, CRT printers, LED printers, crystal printers, and laser plate making.

[Examples] Examples 1 to 7 5 g of methoxymethylated nylon (number average molecular weight: 32,000) and 10 g of alcohol-soluble copolymerized nylon (number average molecular weight: 29,000) on 95 g of methanol on an aluminum support.
Is applied with a Meyer bar, and the film thickness after drying is
An undercoat layer of 1.0 μm was provided.

Next, 5 g of the pigment of the compound example (1) was added to 95 g of cyclohexanone and 2 g of butyral resin (butyralization degree: 63 mol%).
Was added to the solution, and dispersed by a sand mill for 20 hours. The thickness of this dispersion after drying on the undercoat layer formed earlier is
The resultant was coated with a Meyer bar and dried to a thickness of 0.2 μm to form a charge generation layer.

Then, 5 g of a hydrazone compound having the following structure 5 g of polymethyl methacrylate (number average molecular weight 100,000) was dissolved in 40 g of chlorobenzene, and this was coated on a charge generation layer with a Meyer bar and dried to form a 20 μm charge transport layer. It was created.

Electrophotographic photoreceptors corresponding to Examples 2 to 7 were prepared in exactly the same manner, except that the compounds of other compound examples were used instead of the pigment of compound example (1).

The electrophotographic photoreceptor thus prepared was negatively charged by corona discharge at −5 KV using an electrostatic copying paper tester (Model SP-428, manufactured by Kawaguchi Electric Co., Ltd.) and left in a dark place for 1 second. Thereafter, exposure was performed with an illuminance of 10 lux using a halogen lamp, and charging characteristics were evaluated.

As the charging characteristics, the surface potential (V ₀ ) and the exposure amount (E1 / 2) required for the surface potential after being left in a dark place to attenuate to half were measured. The results are shown.

Comparative Example 1 An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except that the compound of Compound Example (1) was replaced with a compound having the following structure, and the charging characteristics were evaluated in the same manner.

V ₀ : −850 V E1 / 2: 19.8 lux.sec From the examples and comparative examples, it can be seen that the electrophotographic photoreceptor of the present invention has sufficient chargeability and excellent sensitivity.

Example 8 Using the electrophotographic photoreceptor prepared in Example 3, fluctuations in the light portion potential and the dark portion potential during repeated use were measured.

As a method, the above-mentioned photoreceptor was attached to a cylinder of an electrophotographic copying machine equipped with a corona charger of -6.5 KV, an exposure optical system, a developing device, a transfer charger, a charge removing exposure optical system and a cleaner.

The initial dark potential (V _D ) and bright potential (V _L ) were set to around -700 V and -200 V, respectively, and the amount of change in the dark potential (ΔV _D ) and the bright potential when using 5,000 times repeatedly were used. The variation (ΔV _L ) was measured.

Note that a negative sign in the fluctuation amount of the potential indicates a decrease in the absolute value of the potential, and a positive sign indicates an increase in the absolute value of the potential.

ΔV _D : 0V ΔV _L : + 5V Comparative Example 2 The electrophotographic photoreceptor used in Comparative Example 1 was used in Example 8.
Potential fluctuations during repeated use were measured in the same manner as described above. The results are shown.

ΔV _D : −215 V ΔV _L : +105 V From the above results, it can be seen that the electrophotographic photoreceptor of the present invention has little potential fluctuation when repeatedly used.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention has high sensitivity and a stable electric potential when repeatedly used by using the barbituric acid derivative or thiobarbituric acid derivative represented by the general formula (1) in the charge generation layer. It has a remarkable effect that it has excellent properties.

Continuation of the front page (72) Inventor Toshie Miyachi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-57-212454 (JP, A) JP-A-57-119355 ( JP, A)

Claims (2)

(57) [Claims] 1. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a barbituric acid derivative or a thiobarbituric acid derivative represented by the following general formula (1). Electrophotographic photoreceptor. General formula In the formula, Y represents an oxygen atom or a sulfur atom, R ₁ represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may be bonded via a bonding group, and R ₂ and R ₃ represents a hydrogen atom, an optionally substituted alkyl group or an aryl group, m is an integer of 2 or 3, n is 1
Or an integer of 2. 2. The electrophotographic photosensitive material according to claim 1, wherein the photosensitive layer comprises at least two layers of a charge generating layer containing a barbituric acid derivative or a thiobarbituric acid derivative represented by the general formula (1) and a charge transporting layer. body.