JP2000242014A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic photoreceptor having good mechanical durability and wear resistance of the surface while retaining satisfactory electric charge transferring ability by incorporating at least one high molecular compound having specified constituent units and a specified copolymerization ratio as an electric charge transferring material into a photosensitive layer. SOLUTION: This electrophotographic photoreceptor has a photosensitive layer containing at least one high molecular compound having constituent units of formulae I and II and a copolymerization ratio of 0.01-1 represented by the relational expression m/(m+n) on the integers (m) and (n) in the formulae as an electric charge transferring material. In the formula I, R3 and R4 are each H, a halogen or alkyl and R5-R8 are each H, a halogen, alkoxy, amino, alkyl or aryl which may have a substituent. In the formula II, R11 and R12 are each H, a halogen alkoxy or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-layer type and a laminated type electrophotographic photoreceptor having a photosensitive layer containing an organic material and used for an electrophotographic printer, a copying machine and the like.

[0002]

2. Description of the Related Art A photoreceptor for electrophotography (hereinafter, also simply referred to as a "photoreceptor") has a structure in which a photosensitive layer having photoconductivity is laminated on a conductive substrate, and has functions of charge generation and charge transport. A single-layer photoreceptor having a single-layer photosensitive layer,
A function-separated laminated photoconductor having a photosensitive layer whose function is separated into a layer contributing to charge generation and a layer contributing to surface charge retention and charge transport is generally used. In recent years, electrophotographic photoreceptors using an organic material have been put into practical use due to advantages such as thermal stability and film forming property. However, these electrophotographic photoreceptors have a problem of charge generation and charge transport. Since it is difficult to form a mechanically stable photosensitive layer using only the functional material that bears it, an electrophotographic photosensitive member that can be put to practical use is realized by forming a photosensitive layer together with a resin binder.

[0003] In recent years, a function-separated laminated photoreceptor in which a photosensitive layer is composed of a laminated layer composed of a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance has become mainstream. Among them, a layer formed by depositing an organic pigment as a charge generating substance or dispersing in a resin binder to form a film was used as a charge generating layer, and an organic low-molecular compound having a charge transport function was dispersed in a resin binder as a charge transport substance. Many negatively charged photoreceptors using a layer as a charge transport layer have been proposed.

As the resin binder for the charge transport layer, transparency and mechanical strength are required, and further, the charging characteristics and sensitivity when a photosensitive layer is formed by dispersing a low-molecular charge transport material as an electrophotographic photosensitive member. Bisphenol A polycarbonate resins and bisphenol Z polycarbonate resins as well as modified polycarbonate resins having bisphenol A polycarbonate as a main repeating structural unit have been put to practical use as substances having good properties.

[0005]

When an electrophotographic photosensitive member is used by the Carlson process, toner, paper, blades, etc. are directly mechanically applied to the surface layer of the photosensitive member in each of charging, developing, transferring, and cleaning processes. Because of the contact process, mechanical durability and wear resistance are required. However, even when the outermost layer is formed using a high-molecular weight binder having high abrasion resistance, a low-molecular weight charge transport material is mixed to provide a charge transport function. Even had limitations. In addition, studies have been made on the improvement of abrasion resistance by using a polymer charge transport material, but a sufficient charge transport ability cannot be obtained with a polymer charge transport material used so far.

Further, in the past, charging and transferring processes of corona discharge of scorotron or corotron type have been mainly used, but recently, a charging roller or a charging brush which does not require a high voltage and does not generate ozone is used. The charging and transfer processes have become popular, and there has been a demand for improved abrasion resistance more than ever.

Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor having excellent mechanical durability and abrasion resistance on the outermost surface while maintaining a sufficient charge transport ability of the electrophotographic photoreceptor. It is in.

[0008]

In order to solve the above-mentioned problems, an electrophotographic photoreceptor of the present invention comprises an electrophotographic photosensitive member having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate. In the photoreceptor, (A) the following general formula (I): [In the formula, m is an integer, and R ¹ and R ² are each independently a hydrogen atom, a halogen atom, an alkoxy group, an amino group,
Represents an alkyl group or an aryl group which may have a substituent, and Y represents the following structural formula (I-1): In the formula, R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom or an alkyl group, and R ^{5 to} R ⁸ each independently represent a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkyl group or a substituent X represents an aryl group which may have the following four structural formulas: (Wherein R ⁹ and R ¹⁰ are each independently selected from the group consisting of groups represented by a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkyl group or an aryl group which may have a substituent). Group｝ or the following structural formula (I-2), 中 In the formula, R ^{3 to} R ⁸ and X are the same as those described above. And a structural unit represented by the following general formula (II): Wherein n is an integer, R ¹¹ and R ¹² each independently represent a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkyl group or an aryl group which may have a substituent; Structural formula (II-1), (Wherein, R ¹³ and R ¹⁴ are each independently a hydrogen atom,
A halogen atom, an alkoxy group, an amino group, an alkyl group or an aryl group which may have a substituent) or the following structural formula (II-2): (Wherein, R ¹⁵ is a halogen atom, an alkoxy group, an amino group, an alkyl group, or an aryl group which may have a substituent). It is characterized in that at least one polymer compound having a copolymerization ratio represented by a relational expression m / (m + n) of integers m and n of 0.01 to 1 is contained as a charge transport material. Things.

Further, another electrophotographic photoreceptor of the present invention comprises:
The photosensitive layer is a laminated type including a charge generation layer and a charge transport layer, and the charge transport layer contains at least one of the polymer compounds as a charge transport material.

Still another electrophotographic photoreceptor of the present invention contains, as a charge transporting substance, a low molecular weight charge transporting substance together with the above-mentioned polymer compound.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the photoreceptor of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the configuration of the laminated photoconductor of the present invention, in which an undercoat layer 2, a charge generation layer 3 and a charge transport layer 4 are sequentially laminated on a conductive substrate 1. FIGS. 2 and 3 show a single-layer type photoreceptor having a structure in which a photosensitive layer 5 is formed on a conductive substrate 1, respectively. In FIG. 2, an undercoat layer 2 is further provided. In the photoreceptor of the present invention, as illustrated in FIGS. 1 to 3, the photosensitive layer may be of a laminated type or a single layer type, but is preferably of a laminated type. Hereinafter, the photoconductor of the present invention will be described in detail by taking the laminated photoconductor of FIG. 1 as an example.

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, film-like, aluminum, stainless steel, nickel or the like. A conductive material may be applied to metal, glass, resin, or the like.

The undercoat layer 2 is made of a layer mainly composed of a resin or an oxide film such as alumite. The undercoat layer 2 prevents unnecessary charge injection from the conductive substrate to the photosensitive layer, covers a defect on the substrate surface, and adheres the photosensitive layer. It is provided as needed for the purpose of improving the performance.
Examples of resin binders include polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, silicone resin, polybutyral resin, polyamide resin, and copolymers thereof. Can be used in combination as appropriate. Further, metal oxide fine particles may be contained in the resin binder. Examples of the metal oxide fine particles include SiO ₂ and TiO ₂ .
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. Let it. In addition, the charge generation layer is required to have high charge generation efficiency and at the same time to have the ability to inject generated charges into the charge transport layer 4. It is desired that the charge generation layer has low electric field dependence and high injection efficiency even at a low electric field. In some cases, a charge generating substance is mainly used and a charge transporting substance is added thereto. As the charge-generating substance, metal-free phthalocyanine, titanyl phthalocyanine, phthalocyanine-based pigments such as tin phthalocyanine, azo pigment, anthantrone pigment, perylene pigment, perinone pigment, squarylium pigment, thiapyrylium pigment, quinacridone pigment, and the like can be used. These pigments may be used in combination.

The resin binder used for the charge generation layer includes polycarbonate resin, polyester resin, polyamide resin, polyurethane resin, epoxy resin, polyvinyl butyral resin, polyvinyl acetal resin, vinyl chloride resin, phenoxy resin, silicone resin, methacrylic acid ester. Resins and their copolymers can be used in appropriate combination.

The charge transport layer 4 contains, as a main component, the polymer charge transport material according to the present invention. Specific examples of such a polymer charge transport material include the following formulas (IV-1) to
Polymer charge transport materials having a repeating unit as shown in (IV-12) can be mentioned.

[0017]

[0018]

[0019]

[0020]

Further, in the present invention, in addition to the polymer charge transport material, a low molecular charge transport material or a resin binder, or both a low molecular charge transport material and a resin binder can be contained. Yes,
This makes it possible to complement the characteristics. in particular,
It is preferable to include a low molecular charge transport material together.
Examples of such low molecular charge transport materials include charge transport materials such as hydrazone compounds, styryl compounds, pyrazoline compounds, pyrazolone compounds, oxadiazole compounds, arylamine compounds, benzidine compounds, stilbene compounds, butadiene compounds, and polyvinylcarbazole. It is possible to use. Specifically, it is preferable to include a low-molecular-weight charge transport material represented by the following formulas (V-1) to (V-6).

[0022]

Examples of the resin binder for the charge transport layer that can be used in combination include polycarbonate resins, polyester resins, polystyrene resins, and polymers and copolymers of methacrylic acid esters. The charge transport layer is formed in such a combination that the compatibility with the charge transport material is good and that the mechanical, chemical and electrical stability and adhesion are secured. The thickness of the charge transport layer is preferably in the range of 10 to 50 μm in order to maintain a practically effective surface potential.

In the case of the single-layer type photosensitive layer 5 as well, the above-mentioned charge generating substance, charge transporting substance and the like can be dispersed in the polymer charge transporting substance according to the present invention and used together with another resin binder. Preferably, the low molecular charge transport material is contained.

In addition, an antioxidant can be appropriately contained in the photosensitive layers of the above-mentioned laminated type and single-layer type photoreceptors for the purpose of improving stability against heat, ozone and the like. Compounds used for such purposes include chromanol derivatives such as tocopherol or etherified compounds or esterified compounds, polyarylalkane compounds, hydroquinone derivatives and monoetherified or dietherified compounds thereof, benzophenone derivatives, benzotriazole derivatives, Examples include thioether compounds, phenylenediamine derivatives, phosphonic acid esters, phosphite esters, phenol compounds, hindered phenol compounds, linear amine compounds, cyclic amine compounds, hindered amine compounds, and the like.

Further, in order to improve the sensitivity, reduce the residual potential, or reduce the characteristic fluctuation during repeated use, the electron acceptor may be added to the photosensitive layers of the above-mentioned laminated and single-layer photosensitive members. A substance can be included. As the electron acceptor, succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride,
Pyromellitic acid, trimellitic acid, trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyanoethylene, tetracyanoquinodimethane, chloranyl, bromanyl, compounds having a high electron affinity such as o-nitrobenzoic acid may be mentioned. it can.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. Example 1 On an aluminum cylindrical substrate, 5 parts by weight of a polyamide resin and 5 parts by weight of titanium oxide fine particles treated with aminosilane were mixed with 45 parts by weight of dichloroethane, 30 parts by weight of methanol, and n-
UCL dissolved in a mixed solvent of 15 parts by weight of butanol
(Undercoat layer) The coating liquid was applied to a 4 μm by dip method.
After coating m, the coating was dried at 120 ° C. for 30 minutes. afterwards,
The upper layer was coated by a dip method with a 0.1 μm coating liquid for a charge generation layer in which titanyl phthalocyanine as a charge generation substance and a resin binder of a vinyl chloride-vinyl acetate copolymer were dispersed in dichloroethane. Further, as the charge transport layer, the average molecular weight is 30,000, and the copolymerization ratio is m /.
After dissolving 10 parts by weight of the polymer charge transport material of the above formula (IV-1) in which (m + n) = 0.3 with 80 parts by weight of a dichloromethane solvent, and coating and forming a film having a thickness of 20 μm by a dipping method. And dried at 100 ° C. for 30 minutes to produce a photoconductor for electrophotography.

Example 2 Instead of the polymer charge transporting substance used in Example 1, an average molecular weight of 30,000 and a copolymerization ratio m / (m + n) =
An electrophotographic photoconductor was prepared in the same manner as in Example 1, except that the polymer charge transport material of the formula (IV-2) of 0.2 was used.

Example 3 Instead of the polymer charge transporting substance used in Example 1, an average molecular weight of 30,000 and a copolymerization ratio m / (m + n) =
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the polymer charge transport material of the above formula (IV-3), which was 0.4, was used.

Example 4 Instead of the polymer charge transporting substance used in Example 1, an average molecular weight of 30,000 and a copolymerization ratio m / (m + n) =
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the polymer charge transport material of the above formula (IV-4) of 0.4 was used.

Example 5 In Example 1, the polymer charge transporting material in the charge transporting layer was changed to 8 parts by weight, and further 2 parts by weight of the distyryl compound of the formula (V-5) was added, and 70 parts by weight of a dichloromethane solvent was added. A photoconductor for electrophotography was prepared in the same manner as in Example 1 except that the photoconductor was dissolved by the method described in Example 1.

Example 6 Instead of the polymer charge transporting substance used in Example 1, the average molecular weight was 30,000 and the copolymerization ratio m / (m + n) =
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the polymer charge transport material of the above formula (IV-5) of 0.5 was used.

Example 7 Instead of the polymer charge transporting substance used in Example 1, an average molecular weight of 30,000 and a copolymerization ratio m / (m + n) =
An electrophotographic photoconductor was prepared in the same manner as in Example 1, except that the polymer charge transport material of the above formula (IV-8), which was 0.4, was used.

Example 8 Instead of the polymer charge transporting substance used in Example 1, an average molecular weight of 30,000 and a copolymerization ratio m / (m + n) =
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the polymer charge transport material of the above formula (IV-12), which was 0.4, was used.

Example 9 In Example 7, 8 parts by weight of the polymer charge transporting material in the charge transporting layer was mixed with 2 parts by weight of the distyryl compound of the formula (V-6), and the mixture was mixed with 70 parts by weight of a dichloromethane solvent. A photoconductor for electrophotography was prepared in the same manner as in Example 7, except that it was dissolved.

COMPARATIVE EXAMPLE 1 Instead of the polymer charge transporting substance used in Example 1, 5 parts by weight of the distyryl compound of the above formula (V-5) as the charge transporting substance and an average molecular weight of 30,000 as the resin binder were used. An electrophotographic photoconductor was prepared in the same manner as in Example 1, except that 5 parts by weight of a bisphenol Z-type polycarbonate resin was mixed.

Comparative Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Comparative Example 1, except that the distyryl compound of the formula (V-6) was used instead of the charge transporting substance used in Comparative Example 1.

The electrophotographic photosensitive members obtained in Examples 1 to 9 and Comparative Examples 1 and 2 were evaluated for electrical characteristics using a photosensitive drum electrical characteristic evaluation apparatus. In corona charging Introduction scorotron, and charged so that charged potential V ₀ photoreceptor surface in the dark of about -650V to measure the charge potential V ₀ which, followed by 5 seconds in the dark and discontinue corona discharge the surface potential V _D were measured after standing was determined potential retention rate V _K5 from the following formula _(%). Potential holding ratio V _K5 (%) = V _D / V ₀ × 100

[0039] Similarly, charges the photoconductor to approximately -650 V, 780 nm, upon exposure of 1 .mu.W / cm ^2, the surface potential was measured exposure _{E 100} required to decay to -100V from -600 V. Furthermore, the residual potential _VR5 after 5 seconds of exposure irradiation was measured.

Next, the photoreceptors for electrophotography obtained in Examples 1 to 9 and Comparative Examples 1 and 2 were evaluated for printing durability of 20,000 sheets using a nonmagnetic one-component developing type laser printer. . The above results are shown in Table 1 below.

[0041]

[Table 1]

From the above results, it was clarified that the photoreceptors of the examples had mechanical durability and abrasion resistance while maintaining sufficient charge transport ability.

[0043]

According to the present invention, it has become possible to provide an organic electrophotographic photoreceptor having a long life by obtaining good abrasion resistance and improving filming resistance.

[Brief description of the drawings]

FIG. 1 is a conceptual cross-sectional view showing one configuration example of a negatively-charged laminated photoreceptor according to the present invention.

FIG. 2 is a conceptual cross-sectional view showing one configuration example of a positively charged single-layer type photoconductor according to the present invention.

FIG. 3 is a conceptual cross-sectional view illustrating a configuration example of another single-layer type photoreceptor according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 undercoat layer 3 charge generation layer 4 charge transport layer 5 single-layer type photosensitive layer

Claims (3)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer containing a charge-generating substance and a charge-transporting substance on a conductive substrate, wherein the photosensitive layer comprises (A) a compound represented by the following general formula (I): [In the formula, m is an integer, and R ¹ and R ² are each independently a hydrogen atom, a halogen atom, an alkoxy group, an amino group,
Represents an alkyl group or an aryl group which may have a substituent, and Y represents the following structural formula (I-1): In the formula, R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom or an alkyl group, and R ^{5 to} R ⁸ each independently represent a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkyl group or a substituent X represents an aryl group which may have the following four structural formulas: (Wherein R ⁹ and R ¹⁰ are each independently selected from the group consisting of groups represented by a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkyl group or an aryl group which may have a substituent). Group｝ or the following structural formula (I-2), 中 In the formula, R ^{3 to} R ⁸ and X are the same as those described above. And a structural unit represented by the following general formula (II): Wherein n is an integer, R ¹¹ and R ¹² each independently represent a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkyl group or an aryl group which may have a substituent; Structural formula (II-1), (Wherein, R ¹³ and R ¹⁴ are each independently a hydrogen atom,
A halogen atom, an alkoxy group, an amino group, an alkyl group or an aryl group which may have a substituent) or the following structural formula (II-2): (Wherein, R ¹⁵ is a halogen atom, an alkoxy group, an amino group, an alkyl group or an aryl group which may have a substituent) represented by a group｝ represented by the following formula: Characterized in that at least one polymer compound having a copolymerization ratio represented by the relational expression m / (m + n) of the integers m and n of 0.01 to 1 is contained as a charge transport material. Photoconductor for electrophotography. 2. The photosensitive layer according to claim 1, wherein the photosensitive layer is a laminated type including a charge generation layer and a charge transport layer, and the charge transport layer contains at least one of the polymer compounds as a charge transport material. 2. The electrophotographic photosensitive member according to 1. 3. The charge transporting material according to claim 1, which further comprises a low molecular weight charge transporting material together with the polymer compound.
The photoconductor for electrophotography according to the above.