JPH07239564A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain a photoreceptor having high sensitivity, hardly deteriorating its sensitivity, less liable to a change of potential characteristics even by a variation of the environment and ensuring superior image quality. CONSTITUTION:In this electrophotographic photoreceptor obtd. by successively laminating an intermediate layer, an electric charge generating layer and an electric charge transferring layer on an electric conductive substrate, the intermediate layer contains alcohol-soluble polyamide resin as the principal component and the electric charge generating layer contains a perylene pigment having a specified crystal form represented by formula I and/or formula II as an electric charge generating material. In the formulae I and II, Z is an org. atomic group forming a hetero ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic organic photoreceptor.

[0002]

2. Description of the Related Art Conventionally, in the Carlson method electrophotographic copying machine, after uniformly charging the surface of the photoconductor, the charge is erased imagewise by exposure to form an electrostatic latent image. The latent image is developed with toner, and then the toner is transferred and fixed on paper or the like.

On the other hand, the photoconductor has been subjected to removal of adhering toner, static elimination, and surface cleaning, and is repeatedly used for a long period of time.

Therefore, the electrophotographic photosensitive member has, of course, electrophotographic characteristics such as good charging characteristics and sensitivity and small dark decay, and in addition, printing durability, abrasion resistance, moisture resistance, etc. in repeated use. It is also required to have good physical properties and resistance (environmental resistance) to ozone generated during corona discharge and ultraviolet rays during exposure.

Conventionally, selenium has been used as an electrophotographic photoreceptor.
Inorganic photoconductors having an inorganic photoconductive substance such as zinc oxide and cadmium sulfide as a main component of a photosensitive layer have been widely used. In recent years, as a photosensitive layer of an electrophotographic photoreceptor, a carrier generating function and a carrier transporting function are shared by different substances, and substances exhibiting each function are selected from a wide range according to desired characteristics, and high sensitivity and high durability are achieved. There is a trend to put organic photoconductors into practical use.

Such a function-separated type organic photoreceptor is conventionally mainly used for negative charging. As described in JP-A-60-247647, a thin carrier generating layer is provided on a support, and a thin carrier generating layer is provided thereon. The structure is such that a relatively thick carrier transport layer is provided. However, the two-layer structure of the charge generation layer and the charge transport layer has problems such as poor charging characteristics, large dark decay, and poor image quality, and an intermediate layer is often provided between the substrate and the charge generation layer. . As the material of this intermediate layer, casein, polyvinyl alcohol resin, polyvinyl butyral resin, cellulose resin and the like are well known, but all have a high residual potential, or the electrical resistance value changes due to environmental changes and There is a problem that the surface potential changes.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photoconductor having high sensitivity, little deterioration in sensitivity, small change in potential characteristics due to environmental changes, and good image quality.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having a photosensitive layer in which an intermediate layer, a charge generating layer and a charge transport layer are sequentially laminated on a conductive substrate, and the intermediate layer is alcohol-soluble. This is achieved by an electrophotographic photoreceptor containing the polyamide resin of, and a perylene pigment represented by the following general formula [I] and / or general formula [II] having a specific crystal type in the charge generation layer.

[0009]

[Chemical 2]

(In the formula, Z is a substituted or unsubstituted organic atomic group that forms a heterocycle.) In the present invention, by containing a polyamide resin in the intermediate layer, charging potential, dark decay characteristics, residual potential, An electrophotographic photosensitive member which is excellent in image characteristics, has excellent sensitivity by containing the perylene pigment having a specific crystal type in the charge generation layer, and exhibits stable characteristics with little potential change even when repeatedly used. can get. That is, it was found that an electrophotographic photoreceptor having extremely excellent characteristics can be obtained by combining an intermediate layer containing a polyamide resin as a main component and a charge generating layer containing the perylene pigment having a specific crystal type as a charge generating substance. It was Further, by performing sublimation purification and acid paste treatment of the perylene pigment, and further forming the charge generation layer using a dispersion liquid in which a polyvinyl butyral resin is dispersed in a ketone solvent, the above-mentioned effect becomes more remarkable. I found it.

[0011]

The structure of the present invention will be described in detail below.

The intermediate layer of the present invention will be described.

The intermediate layer may have a function as an adhesive layer between the conductive substrate and the photoconductive layer, and may also serve as a barrier layer for preventing charge injection from the substrate. Therefore, it is necessary that the solvent is not easily attacked by the solvent used for coating the upper photosensitive layer.

A copolymer type or modified type alcohol-soluble polyamide resin is used for the intermediate layer, and examples of the copolymer type polyamide include nylon 6,
Copolymers of 8, 11, 12, 66, 610, 612 and the like, specifically, (1) Daiamide T-170 (manufactured by Daicel-Huls Co., Ltd.) Nylon 12-based copolymer (2) Alamin CM8000 (manufactured by Toray Industries, Inc.) 6/66/610/12 Copolymer Nylon (3) Ultramid 1c (manufactured by BASF Japan Ltd.)
6/66/610 Copolymer Nylon (4) Elbamide 8061 (manufactured by DuPont Japan Ltd.)
6/66/610 copolymer nylon and the like are preferably used.

Examples of the modified type polyamides include Nyl-methyl modified nylon 6, Nylon 6 modified with methoxymethyl, Nylon 8 modified with N-ethyl and Nylon 8 modified with ethoxymethyl. In particular, the methoxymethyl-modified polyamide resin of nylon 6 is preferable, and specifically, (1) Lucca Mide 5003 (manufactured by Dainippon Chemical Industry Co., Ltd.) (2) Lucca Mide 5216 (Dainippon Chemical Industry Co., Ltd.) (3) Toresin F30 (manufactured by Teikoku Sangyo Kagaku Co., Ltd.) (4) Toresin EF-20T (manufactured by Teikoku Sangyo Kagaku Co., Ltd.) and the like are used.

Examples of the solvent used include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol and the like.

Although the film thickness of the intermediate layer is arbitrarily set, it is 10 μm.
It is preferably m or less, particularly 1 μm or less.

The intermediate layer can be formed by a suitable method such as spray coating, dip coating, knife coating or roll coating.

The effect of chargeability due to the formation of the intermediate layer is particularly remarkable when the conductive base material is a metal such as Al or Ni.

Next, the charge generation layer will be described.

In the present invention, by containing the perylene pigment according to the present invention in the charge generation layer, an electrophotographic photosensitive member having high sensitivity and excellent stability of repetitive potential can be obtained. In the charge generation layer, for example, the charge generation substance is made into fine particles (preferably a particle size of 5 μm or less, more preferably 1 μm or less) in a dispersion medium using a ball mill, a sand grinder, etc., and if necessary, a binder resin and / or a charge. It can be formed by providing an intermediate layer on a conductive support using a dispersion liquid in which a transport substance is added and mixed and dispersed, and applying the intermediate layer thereon.

As another method, it can be formed by providing an intermediate layer on a conductive support and depositing a pigment in a thin film thereon in vacuum. However, as a result of the investigations by the present inventors, when the charge generation layer is formed by the vacuum deposition method, defects such as pinholes and abnormal deposits are often generated in the charge generation layer film, and the charge generation is caused by coating. It has been found that the image quality is better when the generating layer film is formed.

The charge generating material of the present invention will be described in detail below.

The charge-generating substance used in the photoreceptor of the present invention has a Bragg angle (2θ ± 0.2 °) of 2θ = 6.3 °, 12.4 °, 25.3 ° in Cu-Kα ray X-ray diffraction measurement.
It has a peak at 27.1 °, the peak intensity at 12.4 ° is the maximum, the half width of the peak is 0.65 ° or more, and 11.5 °.
Is a perylene pigment having a specific crystal form that does not show a clear peak in the above formula and having a structure defined by the above general formula [I] and / or general formula [II].

The above general formula [I] and / or general formula [II]
Preferred examples of Z in the structural formula defined by are benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyridine ring, pyrimidine ring, pyrazole ring, anthraquinone ring, and the like. Preferably there is. The aromatic ring represented by Z may be substituted, and as the substituent, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an asyl group, an acyloxy group, an amino group, a carbamoyl group, a halogen atom. , Nitro group, cyano group and the like.

Furthermore, it is preferable that the perylene pigment according to the present invention is subjected to sublimation purification treatment and acid paste treatment.

Specific examples of compounds of the perylene pigment according to the present invention are shown below, but the present invention is not limited thereto.

[0028]

[Chemical 3]

These exemplified compounds are disclosed in, for example, JP-A
It is synthesized by the method described in JP-A-49-128734 and JP-A-59-59686.

In general, in order to obtain high-sensitivity photoconductor characteristics, it is first necessary to obtain a uniform coating film in which charge generating substances are atomized. That is, in the dispersion atomization step, the first important thing is to atomize the charge generating substance. However, as a result of the study by the present inventors, the perylene pigment of the general formula [I] of the present invention is crystallized by a strong shearing force applied for particle pulverization depending on the sensitizing effect by atomization, depending on the method of atomization. In some cases, physical damage to the inside or the surface may occur, resulting in a desensitizing effect, and as a result, the sensitivity characteristics may rather show a marked decrease tendency. Therefore, it is preferable that the atomization of the pigment proceeds with a shear force as small as possible. In the present invention,
It is preferable to use an acid paste treatment to use a pigment having a small particle size and a uniform size.

As the solvent or dispersion medium used for forming the charge generation layer of the present invention, n-butylamine, diethylamine, ethylenediamine, isopropanolamine,
Triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone,
Methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,
2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cellosolve and the like can be mentioned. The present invention is not limited to these, but when a ketone solvent is used, the sensitivity, potential change during repeated use and the like are further improved. Further, these solvents may be used alone or as a mixed solvent of two or more kinds.

As the binder resin used in the charge generation layer, polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral,
Polyvinyl formal, polystyrene and the like are used.
The present invention is not limited to these, but when a polyvinyl butyral resin is used, the sensitivity, potential change during repeated use and the like are further excellent. These binder resins are
They can be used alone or as a mixture of two or more kinds.

In the charge generation layer formed as described above, the weight ratio of the charge generation substance to the binder is preferably 100: 0 to 1: 100.

If the content ratio of the charge generating substance is less than this range, the photosensitivity is low and the residual potential is increased. If it is more than this range, the dark decay is increased and the receptive potential is lowered.

When the charge-generating layer contains a charge-transporting substance, the weight ratio of the charge-generating substance to the charge-transporting substance is preferably 10:10 to 10: 1000, and particularly preferably 10 : 0 to 10: 100.

The thickness of the charge generation layer formed is preferably 0.01 to 10 μm.

As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method or a bead coating method can be used.

The charge transport layer in the present invention will be described.

The charge transport layer is formed of a charge generating substance and a binder resin.

The charge-transporting substance used in the present invention is not particularly limited, but for example, oxazole derivative, oxadiazole derivative, thiazole derivative, thiadiazole derivative, triazole derivative, imidazole derivative, imidazolone derivative, imidazolidine derivative, bisimidazole. Lysine derivative, styryl compound, hydrazone compound, benzidine compound, pyrazoline derivative, stilbene compound, amine derivative, oxazolone derivative, benzothiazole derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative,
Phenazine derivative, aminostilbene derivative, poly-N-
Examples thereof include vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene and the like.

The binder resin used in the charge transport layer can be appropriately selected and used from a wide range of insulating resins. Preferred binder resins include polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polycarbonate resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers. , Vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin,
Examples of the insulating resin include phenol-formaldehyde resin, poly-N-vinylcarbazole, and polysilane, but are not limited thereto. These binder resins may be used alone or in combination of two or more.

Further, as the solvent used for forming the charge transport layer, aromatic hydrocarbons such as benzene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, methylene chloride, chloroform, ethylene chloride and the like. Ordinary organic solvents such as halogenated aliphatic hydrocarbons, cyclic or linear ethers such as tetrahydrofuran and ethyl ether may be used alone or in combination of two or more.

The compounding ratio of the binder resin and the charge transport material is 1:10.
˜500, and more preferably 1:20 to 150. The thickness of the charge transport layer is set to 1 to 100 μm, more preferably 5 to 50 μm.

As the coating method, the same method as that for the charge generation layer can be used.

Further, various additives may be incorporated for the purpose of improving the function of the charge transport layer.

[0046]

EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited thereto.

(Synthesis Example) Perylene-3,4,9,10-tetracarboxylic dianhydride 39.2 g, o-phenylenediamine 32.4 g,
800 ml of α-chlornaphthalene was mixed and reacted at 260 ° C for 6 hours. After cooling, the precipitated crystals were collected by filtration and repeatedly washed with methanol. Exemplified compound A-1 was synthesized by heating and drying.

(Sublimation Example) The Exemplified Compound A-1 obtained by the above Synthesis Example was purified by sublimation under heating conditions of 500 ° C. under a pressure of 5 × 10 ^{−4 to} 5 × 10 ⁻³ torr. Volatile impurities were removed using a shutter. The obtained purified crystals were subjected to the same sublimation treatment once more to be further purified. The product that has undergone the sublimation operation twice in this way is referred to as a sublimated product (SUB product) of Exemplified Compound A-1.

(Example of Acid Paste Treatment) A solution prepared by dissolving 20 g of the sublimated product of Exemplified Compound A-1 in 600 ml of concentrated sulfuric acid was filtered through a glass filter and then dropped into 1200 ml of pure water for precipitation. This was collected by filtration, washed thoroughly with pure water, and then dried. The thus obtained product is exemplified compound A-1.
It is referred to as an acid paste treated product (AP product).

(Production of Photoreceptor 1) Copolymerized polyamide resin CM8000 (Toray Industries, Inc.) 30 g was put into a mixed solvent of methanol 900 ml and 1-butanol 100 ml and dissolved. This solution was applied by dip coating on an aluminum drum having an outer diameter of 80 mm and a length of 355.5 mm to form an intermediate layer having a thickness of 0.5 μm. Subsequently, 6 g of polyvinyl butyral resin S-REC BLS (Sekisui Chemical Co., Ltd.) was added to methyl ethyl ketone (Kanto Chemical Co., Ltd.).
Co., Ltd.), dissolved in 1000 ml, and further mixed with 28 g of AP product of Exemplified Compound A-1 obtained by the above-mentioned method, and then dispersed with 2000 g of glass beads having a diameter of 1 mm for 15 hours using a sand mill to obtain a dispersion liquid. Got 1. Using this solution, a charge generation layer having a thickness of 0.5 μm was formed by dip coating on the intermediate layer.

At this time, the obtained dispersion liquid was applied onto a glass plate a plurality of times and dried to form a dry solid film having a thickness of about 200 μm, which was then subjected to X-ray diffraction using Cu-Kα rays. When the spectrum was measured, the Bragg angle (2θ ±
0.2 °) has 2θ = 6.3 °, 12.4 °, 25.3 °, 27.1 °, the peak intensity at 12.4 ° is maximum, and at the same time the half width of the peak is 0.86 ° and a clear peak at 11.5 °. It was found that the crystals did not show.

Then, 200 g of the following compound T and polymer B 2
00 g was dissolved in 1000 ml of dichloromethane (Kanto Chemical Co., Inc.). Using this solution, a charge transport layer having a thickness of 20 μm was formed on the charge generation layer by dip coating.

Finally, it was heated and dried at 100 ° C. for 1 hour to prepare a photoreceptor 1 in which an intermediate layer, a charge generation layer and a charge transport layer were sequentially laminated. The X-ray diffraction spectrum is shown in FIG.

[0054]

[Chemical 4]

(Preparation of Photoreceptor 2) 1,2-dichloroethane was used in place of the solvent methyl ethyl ketone in the dispersion 1 and the dispersion sand mill had 2500 g of glass beads, and the dispersion 2 was obtained by dispersing for 20 hours. Was used to form a charge generation layer, and as shown in Table 2, the polyamide resin CM-8000 in the intermediate layer was replaced with a modified polyamide resin lucamide 50.
Photoconductor 1 except that 03 (Dainippon Ink and Chemicals Co., Ltd.) was used
Photoreceptor 2 was prepared in the same manner as in.

When the X-ray diffraction spectrum of the dispersion 2 was measured, as shown in Table 1, the peak intensity at 12.4 ° was the maximum, the half width of the peak was 0.94, and a clear peak was found at 11.5 °. It turned out not to show.

(Preparation of Photoreceptor 3) Tetrahydrofuran was used in place of the solvent methyl ethyl ketone in the dispersion 1, and the amount of glass beads in the dispersion sand mill was 1500.
A photoconductor 3 was prepared in the same manner as the photoconductor 1 except that the charge generation layer was formed by using the dispersion liquid 3 obtained by dispersing for 10 hours. When the X-ray diffraction spectrum of the dispersion 3 was measured, it was found that the peak intensity at 12.4 ° was the maximum, the half-value width of the peak was 0.68 °, and there was no clear peak at 11.5 °.

(Preparation of Photoreceptor 4) As shown in Table 2, a polyvinyl butyral resin S-REC BH-3 (manufactured by Sekisui Chemical Co., Ltd.) was used in place of the resin CM-8000 of the intermediate layer of the photoreceptor 1 described above. Photoconductor 4 (for Comparative Example 1) in the same manner as photoconductor 1
Was produced.

(Production of Photoreceptor 5) Photoreceptor 1 except that Dispersion 4 containing Perylene Pigment G2 having the following structure was used in place of the AP product of Exemplified Compound A-1 contained in Dispersion 1 above.
Photoreceptor 5 (for Comparative Example 2) was prepared in the same manner as in.

[0060]

[Chemical 5]

(Preparation of Photoreceptor 6) Photoreceptor 6 was prepared in the same manner as in Photoreceptor 1 except that the intermediate layer of Photoreceptor 1 was omitted as shown in Table 2.
(For Comparative Example 3) was produced.

(Preparation of Photoreceptor 7) Same as Photoreceptor 1 except that Dispersion 5 obtained by carrying out dispersion for 5 hours using ultrasonic dispersion is used instead of the sand mill which is the dispersion means of Dispersion 1. Then, a photoconductor 7 (for Comparative Example 4) was produced.

When the X-ray diffraction spectrum of the dispersion 5 was measured, as shown in Table 1, the peak intensity at 12.4 ° was the maximum, and the full width at half maximum of the peak was 0.60 ° and 11.5 °.
It was found that there is a clear peak at.

(Preparation of Photoreceptor 8) Exemplified Compound A-instead of AP Product of Exemplified Compound A-1 contained in Dispersion 1
A photoconductor 8 (for Comparative Example 5) was prepared in the same manner as the photoconductor 1 except that the dispersion liquid 6 containing the sublimated product (SUB) of No. 1 was used.

The X-ray diffraction spectrum of the dispersion 6 was measured, and as shown in Table 1, it did not have a maximum peak intensity at 12.4 °, had a maximum peak intensity at 27.1 °, and had a maximum peak intensity of 12.4 °. The half-value width of the peak was 0.68 °, and it was found that there was no clear peak at 11.5 °. The X-ray diffraction spectrum is shown in FIG.

(Preparation of Photoreceptor 9) Exemplified Compound A-1 was used in place of the AP product of Exemplified Compound A-1 contained in the dispersion.
Sublimation product (SUB) of the present invention, and instead of methyl ethyl ketone as a dispersion medium, toluene-isopropyl alcohol (1:
A photoconductor 9 (for Comparative Example 6) was prepared in the same manner as the photoconductor 1 except that the dispersion liquid 7 containing 1) was used.

When the X-ray diffraction spectrum of the dispersion 7 was measured, it had a maximum peak intensity at 27.1 ° as shown in Table 1, a half value width of the peak at 12.4 ° of 0.52 °, and a peak of 11.5. It was found to have a clear peak at °.

[0068]

[Table 1]

[0069]

[Table 2]

(2) Evaluation Photoreceptors 1 to 9 were mounted on U-BIX 4155 manufactured by Konica Corp.
Image evaluation was performed on 100,000 sheets in an environment of ℃ and 60% relative humidity. Also, 33 ℃, relative humidity 80% and 10 ℃, relative humidity
The surface potential of the photoconductor was measured in a 20% environment, and the fluctuation range of the surface potential due to the environment was evaluated.

[0071]

[Table 3]

In the table, V _b and V _W are reflection densities of 1.
The surface potential of the photoconductor corresponding to a document of 3, 0.00 is shown.

[0073]

According to the present invention, it is possible to provide a photoconductor having high sensitivity, little deterioration in sensitivity, small change in potential characteristics due to environmental changes, and good image quality.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction spectrum diagram in the present invention.

FIG. 2 is an X-ray diffraction spectrum diagram outside the present invention.

Claims (3)

[Claims] 1. An intermediate layer, a charge generation layer, and
In an electrophotographic photoreceptor in which charge transport layers are sequentially laminated, the intermediate layer contains an alcohol-soluble polyamide resin as a main component, and the charge generation layer has a Bragg angle (2θ of 2θ in an X-ray diffraction measurement with respect to Cu-Kα rays. ± 0.2 °) is 2
Has peaks at θ = 6.3 °, 12.4 °, 25.3 °, 27.1 ° 12.
The peak intensity at 4 ° is the maximum, and the full width at half maximum of the peak is 0.6.
Dispersion in which a perylene pigment represented by the following general formula [I] and / or general formula [II] which is 5 ° or more and does not show a clear peak at 11.5 ° is dispersed in an organic solvent together with a polymer binder resin. An electrophotographic photosensitive member characterized by being formed using a liquid. [Chemical 1] (In the formula, Z is a substituted or unsubstituted organic atomic group forming a heterocycle.) 2. The electrophotographic photosensitive member according to claim 1, wherein the pigment has been subjected to sublimation purification and acid paste treatment. 3. The electrophotographic photoreceptor according to claim 1, wherein the organic solvent is a ketone solvent and the polymer binder resin is a polyvinyl butyral resin.