JPH0527470A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having high sensitivity and high durability. CONSTITUTION:A middle layer and a photosensitive layer are successively formed on an electric conductive substrate to obtain an electrophotographic sensitive body. The middle layer contains a naphthalenedicarboxylic acid imide compd. represented by the formula (where R is <=8C alkyl or aralkyl, each of R' and R'' is <=8C alkylene, R' and R'' may be different from each other, Rc is <=8C cycloalkylene or arylene, each of A1 and A2 is H, <=4C alkyl, nitro, cyano, carboxylic ester or halogen and each of k, m and n is 0 or 1 but all of k, m and n are not 0).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor,
More specifically, the present invention relates to a highly sensitive and highly durable electrophotographic photoreceptor containing a specific naphthalenedicarboxylic acid imide compound as an acceptor compound in the intermediate layer.

[0002]

2. Description of the Related Art In recent years,
The development of copying machines and printers using electrophotography is remarkable, and various forms, types, and functions of models have been developed according to the application, and a wide variety of photoconductors to be used are being developed. .. Conventionally, inorganic compounds such as cadmium sulfide and selenium alloy have been mainly used as electrophotographic photoreceptors from the viewpoint of sensitivity and durability. However, these often use harmful substances and cause pollution. Further, when using a selenium alloy having good sensitivity, it is necessary to form a thin film on a conductive support by a vapor deposition method or the like, resulting in poor productivity and high cost.

On the other hand, the organic photoconductor can be incinerated,
It has the advantage of being pollution-free, and many of them can be formed into thin films by coating and are easy to mass-produce. Therefore, it has an advantage that the cost can be significantly reduced and that it can be processed into various shapes depending on the application. As the organic photoreceptor, a charge generating layer in which a charge generating material such as an azo compound or a phthalocyanine compound is dispersed is provided on a conductive support, and a hydrazone compound, a triarylamine compound, a stilbene compound or the like is further typified by the charge generating layer. The function-separated type in which a charge transport layer containing a hole transport material is provided is mainly used.

However, if these photosensitive layers are simply provided on the conductive substrate, defects on the surface of the conductive substrate, that is, scratches, corrosion,
Surface defects such as impurities are often reflected in the image as they are, and often cause image defects such as black spots and white spots. In addition, since the adhesiveness between the conductive substrate and the photosensitive layer is poor, the entire surface may be peeled off from a slight scratch on the photosensitive layer. In order to prevent them, many photoreceptors are provided with a barrier layer and an intermediate layer (also referred to as an undercoat layer) as an adhesive layer. As the intermediate layer, an insulating organic polymer having a submicron film thickness is mainly provided in the form of a thin film, but since it has an insulating property, it has a major drawback that it causes a reduction in the sensitivity of the photoconductor. There is. In addition, space charges are accumulated at the interface between the intermediate layer and the photosensitive layer, which may cause fatigue of the photoconductor such as increase in residual potential and decrease in initial potential.

Various methods have been proposed for the purpose of preventing these problems. One is a method of dispersing an inorganic conductive filler in the intermediate layer, one is a method of using an ion conductive polymer as the intermediate layer, and one is an electron-transporting compound having an acceptor property in the intermediate layer. It is a method to include. Titanium oxide and tin oxide are used as the inorganic filler (Japanese Examined Patent Publication No. 63-19869), but since these are dispersed in the intermediate layer paint, it is technically difficult to prepare the dispersion liquid and pot life. Accompanied by. Further, image defects due to non-uniform dispersion are also caused. As the ion-conductive polymer, for example, water-soluble polymers such as soluble polyamide and cellulose, and alcohol-soluble polymers are used, but their problems have not been solved because of their low conductivity. Further, as the electron-transporting compound having an acceptor property, for example, acceptor compounds such as trinitrofluorenone and tetracyanoquinodimethane are used, but these have a problem in safety, stability, and compatibility, and when repeatedly used. It often decomposes.

As described above, even when the intermediate layer is provided, there still remains a serious problem that the sensitivity and durability are deteriorated.
There is a strong demand for high-performance photoconductors that are improved from these.
The object of the present invention is exactly at this point, and as a solution to this problem, it is to provide an electrophotographic photoreceptor containing an excellent acceptor compound in the intermediate layer.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems, and as a result, completed the present invention. That is, the present invention is an electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are sequentially provided on a conductive support, wherein the intermediate layer contains a naphthalene dicarboxylic acid imide compound represented by the general formula (1), The present invention provides an electrophotographic photosensitive member.

[0008]

[Chemical 2]

(Wherein R is an alkyl group or aralkyl group having 8 or less carbon atoms, R'and R "are the same or different and are alkylene groups having 8 or less carbon atoms, and Rc is a cycloalkylene group having 8 or less carbon atoms or Represents an arylene group, A ₁ and A ₂ are the same or different and each represents a hydrogen atom, an alkyl group having 4 or less carbon atoms, a nitro group, a cyano group, a carboxylic acid ester group or a halogen atom, and k, m and n are They are the same or different and are integers of 0 or 1, and k, m and n are not all 0.) In the general formula (1), R ′ and R ″ are the same or different and have 8 or less carbon atoms. A linear or branched alkylene group of, for example, methylene, ethylene, propylene, trimethylene, butylene, isobutylene, tetramethylene, n-pentylene, isopenylene, neopentylene, n-hexylene, - it may be mentioned groups such as octylene, preferably methylene group, ethylene group. Rc represents a cycloalkylene group having 8 or less carbon atoms or an arylene group, and examples of the cycloalkylene group include:
Examples thereof include groups such as cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene and cyclooctylene, and a cyclohexylene group is preferable.
Further, examples of the arylene group include a phenylene group and a naphthylene group. R represents an alkyl group having 8 or less carbon atoms or an aralkyl group, such as methyl, ethyl,
Examples thereof include groups such as n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-heptyl and n-octyl. A benzyl group can be mentioned as the aralkyl group. k, m, and n are the same or different and are integers of 0 or 1, and all are not 0.

In the general formula (1), A ₁ and A ₂ are the same or different and each independently represent a hydrogen atom, an alkyl group having 4 or less carbon atoms, a nitro group, a cyano group, a carboxylic acid ester group or a halogen atom. Examples of the alkyl group having the number of 4 or less include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and the like. Examples of the halogen atom include chlorine atom, fluorine atom and bromine atom.

The naphthalenedicarboxylic acid imide compound represented by the general formula (1) used in the present invention can be synthesized according to a known method used for synthesizing ordinary carboxylic acid imides. For example, the general formula (2) H ₂ N- (R ") _n- (Rc) _m- (R ') _k -COOR (2) (wherein R, R', R", Rc, k, m, n is the same as formula (1))
It can be obtained by condensing the ω-amino acid ester represented by and naphthalene dicarboxylic acid anhydride.
As another method, first, the general formula (3) H ₂ N- (R ") _n- (Rc) _m- (R ') _k -COOH (3) (wherein R, R', R", Rc, k, m and n are the same as in formula (1))
The target compound can be obtained in high yield by condensing the ω-amino acid represented by and the naphthalene dicarboxylic acid anhydride and then esterifying.

The N-substituted alkyl group of the naphthalene dicarboxylic acid imide compound represented by the general formula (1) thus produced is substituted with a carboxylic acid ester group.
By doing so, a naphthalenedicarboxylic acid imide compound having an electron-donating group, which has been known as a photoconductive compound in addition to exhibiting a high acceptor property (for example, Journal of the American Chemical Society, Vol. 89). , No. 23, pp. 5925 (1967
)) And the fluorenone-based acceptor compound are much more stable, and the compatibility with solvents and binders has been greatly improved. In addition, there was almost no crystallinity, the amorphous state was maintained at room temperature, and no deterioration was observed during use. Particularly, those having m = 1 in the general formula (1) and having a bulky cycloalkylene group or arylene group in the carboxylic acid ester group exhibit high performance and are preferable.

Typical examples of the naphthalenedicarboxylic acid imide compound represented by the general formula (1) used in the present invention include the following compounds (compounds (4) to (46)). The invention is not limited to these.

[0014]

[Chemical 3]

[0015]

[Chemical 4]

[0016]

[Chemical 5]

[0017]

[Chemical 6]

[0018]

[Chemical 7]

[0019]

[Chemical 8]

[0020]

[Chemical 9]

These compounds are soluble in many solvents, for example, aromatic solvents such as benzene, toluene, xylene, tetralin and chlorobenzene; halogen compounds such as dichloromethane, chloroform, trichloroethylene, tetrachloroethylene and carbon tetrachloride. Solvents; ester solvents such as methyl acetate, ethyl acetate, propyl acetate, methyl formate, ethyl formate; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone; ether solvents such as diethyl ether, dipropyl ether, dioxane, tetrahydrofuran; methanol ,ethanol,
It is soluble in alcohol solvents such as isopropyl alcohol; dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like.

In producing the electrophotographic photosensitive member,
First, an intermediate layer containing a naphthalenedicarboxylic acid imide compound represented by the general formula (1) is formed into a thin film on a conductive support. As the base material of the conductive support, a metal such as aluminum or nickel, a metal vapor-deposited polymer film, a metal laminated polymer film, or the like can be used, and the conductive support is in a drum shape, a sheet shape, or a belt shape. To form.

The intermediate layer comprises a naphthalenedicarboxylic acid imide compound represented by the general formula (1) and a binder, and these are dissolved in a solvent to prepare a coating material, which is formed into a thin film by coating. The binder used is not particularly limited, and examples thereof include condensation polymers such as polycarbonate, polyarylate, polyester, and polyamide; polyethylene, polystyrene, styrene-acrylic copolymers; polyacrylate, polymethacrylate, polyvinyl alcohol, Polyvinyl butyral, polyvinyl formal,
Addition polymers such as polyacrylonitrile, polyacrylamide, acrylonitrile-butadiene copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer; natural polymers such as cellulose, amylose, amylopectin; polysulfone, polyether sulfone, silicone resin Etc. are appropriately used, and one kind or a mixture of two or more kinds can be used. Among these, polyamide resin,
Polyvinyl alcohol is preferred.

The amount of the naphthalene dicarboxylic acid imide compound represented by the general formula (1) is 5% by weight to 100% by weight, preferably 10% by weight to 70% by weight, based on the binder.
Is. If the amount is more than 100% by weight, the quality of the film as the intermediate layer becomes very poor, which is not preferable. On the other hand, if it is less than 5% by weight, the concentration of the naphthalenedicarboxylic acid diimide compound represented by the general formula (1) becomes too low, and the effect cannot be expected. The naphthalene dicarboxylic acid imide compound represented by the general formula (1) can be used alone or in combination of two or more kinds, and other conventionally known acceptor compounds can be used at the same time.

In the thin film forming method, first, the naphthalene dicarboxylic acid imide compound represented by the general formula (1) and the binder are dissolved in a solvent. The solvent used is not particularly limited, and examples thereof include aromatic solvents such as benzene, toluene, xylene, tetralin, and chlorobenzene; halogen solvents such as dichloromethane, chloroform, trichloroethylene, tetrachloroethylene, carbon tetrachloride; methyl acetate, acetic acid. Ester-based solvents such as ethyl, propyl acetate, methyl formate, ethyl formate; ketone-based solvents such as acetone, methyl ethyl ketone, cyclohexanone; ether-based solvents such as diethyl ether, dipropyl ether, dioxane, tetrahydrofuran; methanol, ethanol,
Alcohol-based solvents such as isopropyl alcohol; solvents such as dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like can be used.

The means for coating the intermediate layer is not particularly limited, and for example, a dip coater, bar coater, calendar coater, gravure coater, spin coater or the like can be used as appropriate, and electrodeposition coating, spraying Coating and the like are also possible. The thickness of the intermediate layer thus provided is 0.1 μm to 2 μm, and if it is thinner than this, the effect as the intermediate layer cannot be expected, and if it is thicker than this, the sensitivity of the photoreceptor is lowered.

A photosensitive layer is provided on the intermediate layer produced as described above. As the photosensitive layer, either a single layer type containing a charge generating material and a charge transporting material in the same layer, or a function separation type consisting of a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material may be adopted. Although possible, the latter will be described in detail below. The charge generation layer is composed of a charge generation material and, if necessary, a binder and an additive.
It can be prepared by a method such as D method or coating method. The charge generating material is not particularly limited, and any organic material or inorganic material can be suitably used as long as it absorbs light having a specific wavelength to be irradiated and efficiently generates charges. Examples of the organic charge generating material include perylene pigments, polycyclic quinone pigments, metal-free phthalocyanine pigments, metal phthalocyanine pigments, bisazo pigments, trisazo pigments, thiapyrylium salts, squarium salts, and azurenium pigments. Examples of the inorganic charge generating material include zinc oxide, cadmium sulfide, selenium, selenium alloy, amorphous silicon, and amorphous silicon carbide. The organic charge generating material can be dispersed mainly in a solvent and a binder to prepare a coating liquid, and the charge generating layer can be formed by coating. The thickness of the formed charge generation layer is preferably 0.1 to 2.0 μm, more preferably 0.1 to 1.0 μm.

The binder used if necessary is not particularly limited as long as it is an insulating resin, and the same binders as those exemplified for the intermediate layer can be used. The amount of the binder used is 0.1 to 3% by weight, preferably 0.1 to 2% by weight, based on the charge generating material. In addition, examples of additives that can be used as needed include antioxidants, quenchers, dispersants, adhesion aids, and sensitizers. The coating means for the charge generation layer is not particularly limited, and for example, a dip coater, a bar coater, a calendar coater, a gravure coater, a spin coater or the like can be used as appropriate, and electrodeposition coating or spray coating is also possible. Etc. are also possible.

Next, a charge transport layer is formed in a thin film on the charge generation layer. As a thin film forming method, a coating method is mainly used.The charge transport material is dissolved in a solvent together with a binder and an additive used if necessary, and then applied on the charge generation layer and then dried. Just do it. The solvent used is not particularly limited as long as it is a solvent in which the charge transport material and the binder used as necessary are dissolved and the charge generation layer is not dissolved. The charge transport material used is not particularly limited, and a charge transport material that is normally used is preferably used. Hydrazone compounds,
Examples thereof include stilbene compounds, triarylamine compounds, pyrazoline compounds, oxadiazole compounds, oxazole compounds, polyvinylcarbazole compounds and triphenylmethane compounds.

The binder used if necessary is an intermediate layer,
The same materials as those used for the charge generation layer can be used. The amount of the binder used is 0.1 to 3% by weight, preferably 0.1 to 2% by weight, based on the charge transport material. If the amount of the binder used is larger than 3% by weight, the concentration of the charge transport material in the charge transport layer becomes small and the sensitivity becomes poor. On the other hand, if it is less than 0.1 weight ratio, the effect as a binder will not be exhibited. Further, as additives used as necessary, antioxidants, quenchers, dispersants,
Adhesion aids, sensitizers, etc. may be mentioned. The coating means for the charge transport layer may be the same as for the intermediate layer and the charge generation layer. The thickness of the charge transport layer thus formed is 10 to 50 μm, more preferably 10 to 50 μm.
30 μm. If the film thickness is larger than 50 μm, it takes a long time to transport the charge, which causes a decrease in sensitivity.
On the other hand, if it is less than 10 μm, the mechanical strength is lowered and the life of the photoreceptor is shortened, which is not preferable.

As described above, an electrophotographic photoreceptor containing the naphthalenedicarboxylic acid imide compound represented by the general formula (1) in the intermediate layer can be prepared. In the present invention, an overcoat layer is further formed on the photosensitive layer. Can be provided.

When the electrophotographic photosensitive member thus obtained is used, first the surface of the photosensitive member is negatively charged by a corona charger or the like. After charging, by exposing, charge is generated in the charge generation layer, and positive charges are injected into the charge transport layer,
This is transported to the surface through the charge transport layer, and the surface negative charges are neutralized. The negative charge in the charge generation layer is injected into the intermediate layer to neutralize the positive charge of the conductive support. On the other hand, negative charges remain in the unexposed areas. In the case of regular development, positive toner is used, and toner adheres to the portion where this positive charge remains, and development is performed. In the case of reversal development, a negative toner is used, and the toner is attached to the portion where the charge is neutralized, and development is performed. The electrophotographic photosensitive member of the present invention can be used in any developing method and can provide high image quality.

[0033]

EXAMPLES The present invention will now be specifically illustrated with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 Polyamide resin (Amilan CM-8000, manufactured by Toray Industries, Inc.)
1 g, naphthalene dicarboxylic acid imide compound (compound (2
0)) 0.5 g with methanol / n-butanol (2/1) 20 ml
And was coated on an aluminum plate with a bar coater so that the film thickness after drying was 0.2 μm, and dried to form an intermediate layer. Next, 5 g of X-type metal-free phthalocyanine, butyral resin (S-REC BM-2, manufactured by Sekisui Chemical Co., Ltd.)
Is dissolved and dispersed in 90 ml of cyclohexanone, and in a ball mill.
Kneaded for 24 hours. The resulting dispersion was applied onto the intermediate layer with a bar coater so that the film thickness after drying was 0.15 μm, and dried to form a charge generation layer. Furthermore, the following formula (4
5 g of diethylaminobenzaldehyde diphenylhydrazone shown in 7), polycarbonate resin (Lexane 131
-111, manufactured by Engineering Plastics Co., Ltd. 5
g was dissolved in 90 ml of dichloroethane, and this was coated on the charge generation layer with a blade coater so that the film thickness after drying was 25 μm, and dried to form a charge transport layer.

[0035]

[Chemical 10]

The electrophotographic photosensitive member produced in this manner was manufactured by Kawaguchi Electric Co., Ltd., an electrostatic copying paper test apparatus EPA-
When charged with a corona voltage of −5.5 kV using 8100, the initial surface potential V ₀ was −780 V. 2 in the dark
The surface potential V ₂ after standing for ₂ seconds became −750V. Then, a semiconductor laser with an oscillation wavelength of 780 nm is irradiated to halve the exposure amount E.
_{When 1/2} was obtained, it was 0.29 μJ / cm ² , and the residual potential V
_R was -3.7V. Next, after repeating the above operation 5000 times and measuring V ₀ , V ₂ , E _1/2 and V _R ,
The voltages were -770V, -760V, 0.30 µJ / cm ² and -8.6V, respectively. In this way, the performance of the photoconductor has not deteriorated,
It showed high sensitivity and high durability.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1 except that the naphthalene dicarboxylic acid imide compound was omitted, and the performance was evaluated. As a result, initial V ₀ , V ₂ , E _1/2 , V
_R is -830V, -820V, 0.75μJ / cm ² , -47.8, respectively.
It was V. Next, after repeating the operation 5000 times, V ₀ , V
_2, E _1/2, was measured for V _R, respectively -800
V, -780V, 0.93μJ / cm ² , -103V, sensitivity,
The durability was poor.

Examples 2 to 10 Photosensitive members were prepared in the same manner as in Example 1 except that the naphthalenedicarboxylic acid imide compounds having the numbers shown in Table 1 were used, and their performances were evaluated. The results are shown in Table 1, and like the results of Example 1, high sensitivity and high durability were exhibited.

[0039]

[Table 1]

Example 11 A photoreceptor was prepared in the same manner as in Example 1 except that a polyvinyl alcohol resin (B-05, manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as the binder for the intermediate layer instead of the polyamide resin. It was produced and the performance was evaluated. As a result, the initial V
_{0, V 2, E 1/2,} V R , respectively -770V, -760
V, 0.30 μJ / cm ² , and −5.5 V. Next, after repeating the operation 5000 times, V ₀ , V ₂ , E _1/2 and V _R were measured and found to be −770 V, −750 V, 0.30 μJ / cm ² , −, respectively.
It was 10.8 V, which was excellent in both sensitivity and durability.

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 11 except that the naphthalene dicarboxylic acid imide compound was omitted, and the performance was evaluated. As a result, the initial V ₀ , V ₂ , E _1/2 ,
V _R respectively ^{-820V, -800V, 0.69μJ / cm 2} , -3
It was 0.4V. Then after repeating the operation 5000 times,
When V ₀ , V ₂ , E _1/2 and V _R were measured, they were −850 V, −840 V, 0.98 μJ / cm ² and −145.6 V, respectively, and both sensitivity and durability were poor.

Comparative Example 3 A photoconductor was prepared in the same manner as in Example 1 except that trinitrofluorenone represented by the following formula (48) was used in place of the naphthalene dicarboxylic acid imide compound, and the performance was evaluated. As a result, initial V ₀ , V ₂ , E _1/2 and V _R were -760V, -740V, 0.32 µJ / cm ² and -6.2V, respectively. Next, after repeating the operation 5000 times, V ₀ , V ₂ ,
E _1/2, was measured for V _R, respectively -530V, -42
It was 0 V, 0.97 μJ / cm ² , and −113.8 V, and was inferior in durability.

[0043]

[Chemical 11]

Claims (1)

Claim: What is claimed is: 1. An electrophotographic photosensitive member comprising a conductive support and an intermediate layer and a photosensitive layer sequentially provided on the conductive support.
An electrophotographic photoreceptor comprising the naphthalene dicarboxylic acid imide compound represented by (1). [Chemical 1] (In the formula, R is an alkyl group or aralkyl group having 8 or less carbon atoms, R ′ and R ″ are the same or different and are alkylene groups having 8 or less carbon atoms, and Rc is a cycloalkylene group or arylene group having 8 or less carbon atoms. A ₁ and A ₂ are the same or different and each represents a hydrogen atom, an alkyl group having 4 or less carbon atoms, a nitro group,
A cyano group, a carboxylic acid ester group or a halogen atom is shown. k, m, and n are the same or different and are integers of 0 or 1, and k, m, and n are not all 0. )