JP2000258935A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photoreceptor which is free of problems in solubility and compatibility in resins and solvents and has high sensitivity and ozone exposure characteristic by incorporating specific butadiene compounds into a photosensitive layer as a charge transfer material. SOLUTION: A charge transfer layer constituting the photosensitive layer is composed of the charge transfer material and a resin binder as essential components. The butadiene compounds expressed by formula I and II are used in combination as the charge transfer material. The compounding ratio of the butadiene compound expressed by the formula II is adequately 2 to 70 pts.wt. per 100 pts.wt. total of the charge transfer material. In the formula I, X1 and X2 may be respectively the same or different and denote hydrogen atoms, halogen atoms, alkyl groups, alkylamino groups or alkoxy groups. In the formula II, X3 to X6 may be respectively the same or different and denote hydrogen atoms, halogen atoms, alkyl groups, alkylamino groups or alkoxy groups and at least one piece is an alkylamino group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing an organic material on a conductive substrate and used in electrophotographic printers, copiers and the like. It relates to a photoreceptor.

[0002]

2. Description of the Related Art Conventionally, photosensitive materials for electrophotographic photosensitive members used in electrophotographic printers, facsimiles, various copying machines, etc. include inorganic photoconductive materials such as selenium or selenium alloy, zinc oxide and cadmium sulfide. Inorganic photoconductive substance such as dispersed in a resin binder, organic photoconductive substance such as poly-N-vinylcarbazole or polyvinylanthracene, organic photoconductive substance such as phthalocyanine compound or bisazo compound A material dispersed in a binder and a material deposited by vacuum deposition are used.

A photoreceptor is required to have a function of retaining surface charge in a dark place, a function of receiving light to generate a charge, and a function of receiving light and transporting a charge. A photoreceptor that combines these functions in one layer is a single-layer photoreceptor, and a photoreceptor that has been separated into a layer that contributes to charge generation and a layer that contributes to charge transport during photoreception is a function-separated laminated photoreceptor That. In recent years, function-separated laminated photoconductors have become the mainstream, among which a charge generation layer in which an organic pigment is deposited or dispersed in a resin as a charge generation material, and an organic low-molecular compound dispersed in a resin as a charge transport material Numerous negatively charged photoreceptors using a charge transport layer formed thereon have been proposed.

[0004] To form an image on the electrophotographic photosensitive member,
For example, the Carlson method is applied. Image formation in this method involves charging a photoreceptor by corona discharge in a dark place, forming an electrostatic latent image such as a character or picture of a document on the charged photoreceptor surface, and forming the formed electrostatic latent image. The development is performed by developing the image with toner and transferring the developed toner image to a support such as paper. The photoreceptor after the transfer of the toner image is subjected to charge elimination, removal of residual toner, light charge elimination, and the like, and then reused.

In recent years, electrophotographic photoreceptors using an organic material have advantages such as flexibility, thermal stability, and film-forming properties as compared with inorganic photoreceptors, and thus have been put to practical use. In.

As the charge generating substance, organic pigments such as phthalocyanine pigments, azo pigments, anthantrone pigments, perylene pigments, perinone pigments, squarylium pigments, thiapyrylium pigments and quinacridone pigments are known.

[0007] Further, as charge transport substances, pyrazoline compounds, pyralozone compounds, hydrazone compounds, oxadiazole compounds, arylamine compounds, benzidine compounds, stilbene compounds, butadiene compounds and the like are known.

[0008] Among the known charge transport materials, certain butadiene compounds are known to have excellent initial characteristics such as sensitivity and residual potential, but they have problems with ozone exposure characteristics. There is. On the other hand, although other butadiene compounds are known to have high sensitivity, they have poor solubility and compatibility with resins and solvents, and thus have problems such as deposition during film formation. Was. As described above, no charge transporting material having all the good characteristics can be present in the related art.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a photoreceptor having a photosensitive layer containing a charge transport material, which eliminates the above-mentioned disadvantages and has excellent electrophotographic characteristics. Is to provide.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, by using butadiene compounds represented by the following general formulas (I) and (II) in combination, The present inventors have found that there can be obtained a photosensitive member having no problem in solubility and compatibility with a resin and a solvent, and having high sensitivity and excellent ozone exposure characteristics, and completed the present invention.

That is, the electrophotographic photoreceptor of the present invention is an electrophotographic organic photoreceptor having a photosensitive layer on a conductive substrate, wherein the photosensitive layer contains the following general formula (I) as a charge transport material: (Wherein X ¹ and X ² may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group or an alkoxy group), and a butadiene compound represented by the following general formula: (II), (Wherein X ³ , X ⁴ , X ⁵ and X ⁶ may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group, or an alkoxy group, and at least one of them is alkylamino A butadiene compound represented by the formula:

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred examples of the compounds represented by the above general formulas (I) and (II) are the following structural formulas (I ') and (II'), respectively. It is a compound represented by these.

Hereinafter, a specific configuration of a preferred example of the photosensitive member of the present invention will be described with reference to the drawings. FIG. 1 (a),
(B) and (c) are conceptual sectional views showing one embodiment of the photoreceptor of the present invention, wherein 1 is a conductive substrate, 2 is an undercoat layer, 3 is a charge generation layer, 4 is a charge transport layer, Reference numeral 5 denotes a surface protective layer, and reference numeral 6 denotes a photosensitive layer. The photosensitive layer is a function-separated type separated into a charge generation layer and a charge transport layer, or a single layer type containing a charge generation substance and a charge transport substance. The photosensitive layer in FIG. 1A is of a negative charge type in which a charge generation layer and a charge transport layer are laminated in this order, and the photosensitive layer in FIG. 1B is opposite to that of FIG. The photosensitive layer of FIG. 1C is a single-layer type, mainly a positively-charged type.

The conductive substrate 1 serves not only as an electrode of the photoreceptor but also as a support for the other layers, and may be cylindrical, plate-like or film-like. A conductive material may be applied to metal, glass, resin, or the like.

The undercoat layer 2 comprises a layer mainly composed of a resin or an oxide film such as alumite, prevents injection of unnecessary charges from the conductive substrate to the photosensitive layer, covers defects on the surface of the substrate, and adheres the photosensitive layer. It is provided as needed for the purpose of improving the performance.
As the resin binder, polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, silicone resin, polyvinyl butyral resin, polyamide resin, and copolymers thereof, etc. They can be used in appropriate combinations. Further, metal oxide fine particles and the like may be contained in the resin binder. As metal oxide fine particles, SiO ₂ ,
TiO ₂ , In ₂ O ₃ , ZrO _2, or the like can be used.

The charge generation layer 3 is formed by vacuum-depositing an organic photoconductive substance or applying a coating liquid in which particles of the organic photoconductive substance are dispersed in a resin binder, and generates light by receiving light. I do. In addition, it is important that the charge generation efficiency is high, and at the same time, the injected property of the generated charge into the charge transport layer 4 is important. Since the charge generation layer only needs to have a charge generation function, its thickness is determined by the light absorption coefficient of the charge generation substance, and is generally 5 μm or less, preferably 1 μm or less. The charge generation layer is mainly composed of a charge generation substance, but may be used by adding a charge transport substance or the like.
Specific examples of the charge generating substance include the following specific examples (III-1) to (III).
Various phthalocyanine compounds shown in -6), azo compounds shown in the following specific examples (III-7) to (III-24), and derivatives thereof can be used. Further, polycyclic quinone pigments such as anthantrone, perylene pigments, perinone pigments, squarylium pigments, thiapyrylium pigments, quinacridone pigments and the like can be used, and these pigments may be used in combination. As the resin binder used for the charge generation layer, polycarbonate resin, polyester resin, polyamide resin, polyurethane resin, epoxy resin, polyvinyl butyral resin, polyvinyl acetal resin, vinyl chloride resin, phenoxy resin, silicone resin, methacrylate resin and These copolymers and the like can be used in appropriate combination.

[0017]

[0018]

[0019]

[0020]

The charge transport layer 4 is a film in which a charge transport material is dispersed in a resin binder. The charge transport layer 4 holds the charge of the photosensitive layer as an insulator layer in a dark place, and stores the charge injected from the charge generation layer at the time of receiving light. Exhibits the function of transport. Charge transport layer 4
Is composed of a charge transport material and a resin binder as main components. In the present invention, an antioxidant can be added for the purpose of improving stability against ozone, light, heat, or the like. In the present invention, as the charge transport material,
The butadiene compounds represented by the general formulas (I) and (II) are used in combination, and the compounding ratio of the butadiene compound represented by the general formula (II) is preferably based on 100 parts by weight of the total charge transporting substance. It is used in the range of 2 to 70 parts by weight, more preferably 5 to 50 parts by weight. It is also possible to use the butadiene compounds represented by the above general formulas (I) and (II) as a main component, and also to use other charge transport substances in combination. Examples of charge transport materials that can be used in combination include charge transport polymers such as hydrazone compounds, styryl compounds, benzidine compounds, stilbene compounds, pyrazoline compounds, pyrazolone compounds, oxadiazole compounds, other amine compounds, and polyvinyl carbazole. As the resin binder, the following specific examples (IV-1) to
Including various polycarbonate resins shown in (IV-7),
Polyester resins, polystyrene resins, polymers and copolymers of methacrylic acid esters, etc. are used, but compatibility with charge transport materials is important in addition to mechanical, chemical and electrical stability, adhesion, etc. .

[0022]

As the antioxidant in the present invention, the compounds shown in the following specific examples (V-1) to (V-45) are used, but they can be used in combination with other antioxidants. When an antioxidant is added to the charge transporting layer, it is preferable that the antioxidant be added in an amount of 0.1 to 100 parts by weight of the total of the charge transporting substance and the resin binder.
001 to 10 parts by weight, more preferably 0.005 to 5 parts by weight. In order to maintain a practically effective surface potential, the thickness of the charge transport layer is preferably in the range of 3 to 50 μm, and more preferably 10 to 40 μm.

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

The surface protective layer 5 can be provided as needed, is made of a material which is excellent in durability against mechanical stress and is chemically stable, and accepts and holds the charge of corona discharge in a dark place. It has the function of transmitting light sensitive to the charge generation layer, transmits light at the time of exposure, reaches the charge generation layer, receives the injected charge, and neutralizes the surface charge It needs a function to make it disappear. The surface protective layer 5 is made of polyvinyl butyral resin, polycarbonate resin, nylon resin, polyurethane resin, polyarylate resin, modified silicone resin such as acrylic-modified silicone resin, epoxy-modified silicone resin, alkyd-modified silicone resin, polyester-modified silicone resin, and urethane-modified silicone. A resin such as a silicone resin as a hard coat agent can be applied. These modified silicone resins can be used alone, but for the purpose of further improving the durability, this resin is combined with SiO ₂ , TiO ₂ , and In ₂ O.
₃ , a mixture with a condensate of a metal alkoxy compound capable of forming a film containing ZrO ₂ as a main component is preferable. The thickness of the surface protective layer depends on the composition of the protective layer, but can be arbitrarily set within a range that does not cause adverse effects such as an increase in residual potential when repeatedly used continuously.

The single-layer type photosensitive layer 6 is a coating film in which a charge generating substance and a charge transporting substance are dispersed in a resin binder, and the above-mentioned charge generating substance, charge transporting substance, resin binder and antioxidant are similarly used. Can be used. The thickness of the single-layer type photosensitive layer 6 is preferably in the range of 3 to 50 μm, more preferably 10 to 50 μm, in order to maintain a practically effective surface potential.
40 μm.

The photosensitive layers of the laminated and single-layered photoreceptors may contain an electron accepting substance as necessary for the purpose of improving sensitivity, reducing residual potential, or reducing characteristic fluctuation during repeated use. As the electron acceptor, succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, pyromellitic acid, trimellitic acid, Examples thereof include compounds having a large electron affinity such as trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyanoethylene, tetracyanoquinodimethane, chloranil, bromanyl, and o-nitrobenzoic acid.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below more specifically based on embodiments. In the following examples, "part" represents "part by weight" and "%" represents "% by weight". Example 1 An undercoat layer dispersion having the following composition was dip-coated on the surface of an aluminum tube and dried at 135 ° C. under normal pressure for 30 minutes to form a 4 μm-thick undercoat layer. Alcohol soluble nylon (CM8000, manufactured by Toray Industries, Inc.) 5 parts Titanium oxide fine particles treated with aminosilane 5 parts Methanol / methylene chloride mixed solvent (6/4) 90 parts

Next, a dispersion for a charge generation layer having the following composition was applied by dip coating and dried at 80 ° C. under normal pressure for 30 minutes to form a film having a thickness of 0.1 μm.
A 3 μm charge generation layer was formed. Titanyloxyphthalocyanine (Structural formula (III-3)) 1 part Vinyl chloride copolymer resin (manufactured by Zeon Corporation: MR-110) 1 part Methylene chloride 98 parts

Next, a solution for a charge transport layer having the following composition was dip-coated and dried at 90 ° C. for 30 minutes under normal pressure to obtain a film having a thickness of 28 μm.
m of the charge transport layer was formed. Butadiene compound (Structural formula (I ')) 8 parts Butadiene compound (Structural formula (II')) 2 parts Polycarbonate resin (Structural formula (IV-2)) 10 parts Methylene chloride 80 parts Electrons as described above. A photoreceptor was prepared.

Example 2 In Example 1, 5 parts of the butadiene compound of the structural formula (I ') and 5 parts of the butadiene compound of the structural formula (II') were used.
A photoreceptor was produced in the same manner as in Example 1 except that the above-mentioned parts were used.

Example 3 In Example 1, 3 parts of the butadiene compound of the structural formula (I ') and 7 parts of the butadiene compound of the structural formula (II') were used.
A photoreceptor was produced in the same manner as in Example 1 except that the above-mentioned parts were used.

COMPARATIVE EXAMPLE 1 The procedure of Example 1 was repeated except that 10 parts of the butadiene compound of the structural formula (I ′) was used and the butadiene compound of the structural formula (II ′) was omitted. The body was made.

COMPARATIVE EXAMPLE 2 Charge transport was performed in the same manner as in Example 1 except that 10 parts of the butadiene compound of the structural formula (II ′) were used and the butadiene compound of the structural formula (I ′) was omitted. Although a layer solution was prepared, it was not completely dissolved in methylene chloride, so that a photoconductor could not be prepared.

Evaluation of Photoreceptor The electrophotographic characteristics of the photoreceptor prepared in the above Examples were evaluated by the following methods. The electrical property evaluation and the ozone exposure property evaluation were performed using a drum test device. In a dark place, the surface potential is charged to about -650 V by corona discharge, and the surface potential V ₀ immediately after the charging is measured. Then, the corona discharge is stopped, and after leaving in a dark place for 5 seconds, the surface potential _{V 5} was measured to determine the potential retention rate _V k5 (%) of according to the following equation. Potential holding ratio V _k5 (%) = (V ₅ / V ₀ ) × 100 V ₀ : Surface potential immediately after charging V ₅ : Surface potential after standing for 5 seconds

Next, a monochromatic light of 1.0 μW / cm ² , which is obtained by dividing the light of a halogen lamp to 780 nm with a filter, is exposed for 5 seconds, and the exposure amount required for the surface potential to become −100 V is determined as the sensitivity E ₁₀₀ ( μJ / cm ² ).

Further, the drum was allowed to stand for 2 hours under an environment of ozone 100 ppm, just before, to determine the potential retention rate _{V k5} and sensitivity _{E 100} after standing immediately after and 24 hours. Table 1 below shows the electrical characteristics of the photoconductors manufactured in Examples 1 to 3 and Comparative Examples 1 and 2.

[0043]

[Table 1]

[0044]

According to the present invention, in an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, the charge transporting material contained in the photosensitive layer is represented by the formulas (I) and (II). By using the butadiene compounds to be used in combination, a photoconductor for electrophotography having good sensitivity and ozone exposure characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a photoreceptor according to the present invention, wherein FIG.
Is the configuration of a negatively-charged function-separated type electrophotographic photoreceptor,
Is the configuration of a positively charged function-separated type electrophotographic photoreceptor, (c)
Represents the configuration of a positively charged single-layer type electrophotographic photosensitive member.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 undercoat layer 3 charge generation layer 4 charge transport layer 5 surface protective layer 6 photosensitive layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirotaka Kobayashi 1-1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Naoki Ito No. 1-1 Fuji Electric Co., Ltd. F-term (reference) 2H068 AA20 BA13 FA02

Claims (1)

[Claims] 1. An organic photoreceptor for electrophotography having a photosensitive layer on a conductive substrate, wherein the charge-transporting substance in the photosensitive layer has the following general formula (I): (Wherein X ¹ and X ² may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group or an alkoxy group) and a butadiene compound represented by the following general formula: (II), (Wherein X ³ , X ⁴ , X ⁵ and X ⁶ may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group, or an alkoxy group, and at least one of them is alkylamino A butadiene compound represented by the formula: