JPH02220063A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body to be used for a copying machine, high in sensitivity and superior in characteristics in repeated uses by using a specified bisazo compound as the electric charge generating material of a photosensitive layer. CONSTITUTION:The charge generating layer 4 is formed by coating with a material prepared by dispersing into a binder resin the particles of the charge generating material 3 of the bisazo compound represented by general formula I in which A is an aromatic heterocyclic group; B is absent or aryl, a heterocyclic group, or a combination of them; n is 0, 1, or 2; and Cp is a coupler residue represented by general formula II, III, IV, or V. This compound receives light and generates charge, and it is important for the compound to have high charge generating efficiency and good injectability of the generated charge to a charge transfer layer 6 and a covering layer 7, and it is preferred to be low in electric field dependency and good in injectability even at the time of low electric field. The charge generating layer can be formed by adding a charge transfer material and the like to the main component of the charge generating material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor using a novel charge-generating substance.

[Conventional technology]

Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) have been made using inorganic photoconductive substances such as selenium or selenium alloys, or inorganic photoconductive substances such as zinc oxide or cadmium sulfide in a resin binder. What is dispersed, po'
Organic photoconductive substances such as J-N-vinylcarbazole or polyvinylanthracene, phthalocyanine compounds, or bisazo compounds dispersed in a resin binder or vacuum-deposited are used. ing.

The photoreceptor also needs to have the function of retaining surface charge in the dark, the function of receiving light and generating charge, and the function of receiving light and transporting charge, but these functions can be achieved in three layers. The so-called single-layer type photoreceptor has both a so-called single-layer type photoreceptor, and the so-called laminated type photoreceptor that has two functionally separated layers: a layer that mainly contributes to charge generation, a layer that contributes to surface charge in the dark, and a layer that contributes to charge transport during light reception. I have a body. For example, the Carlson method is applied to image formation by electrophotography using these photoreceptors. Image formation in this method involves charging the photoconductor in a dark place by corona discharge, forming an electrostatic latent image such as text or pictures on the original on the surface of the charged photoconductor, and forming an electrostatic latent image on the surface of the charged photoconductor. After the toner image has been transferred, the photoreceptor is subjected to static electricity removal, removal of residual toner, photostatic static removal, etc. before being reused. be done.

In recent years, electrophotographic photoreceptors using organic materials have been put into practical use due to their advantages such as flexibility, thermal stability, and film-forming properties. For example, 'poly N-vinylcarbazole and 2
．． 4.7-) dinitrofluoren-9-one (described in U.S. Pat. No. 3,484,237),
Photoreceptor containing organic pigment as main component (Japanese Patent Application Laid-Open No. 47-3754
3), and a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (described in JP-A-47-10735). Furthermore, many new azo compounds and perylene compounds have been put into practical use.

[Problem to be solved by the invention]

However, although organic materials have many advantages that inorganic materials do not have, the current situation is that organic materials that fully satisfy all of the characteristics required for electrophotographic photoreceptors have not been obtained, such as high sensitivity and A photoreceptor with excellent repeatability is strongly desired.

The present invention has been made in view of the above-mentioned points, and its object is to provide electrophotography for copying machines with high sensitivity and excellent repeatability by using a new organic material that has never been used as a charge-generating substance in the photosensitive layer. The purpose of the present invention is to provide a photoreceptor for use in the manufacturing industry.

[Means to solve the problem]

As a result of intensive studies to achieve the above object, the present inventors found that a specific bisazo compound is effective, and based on this knowledge, the present invention was accomplished.

According to the present invention, the above-mentioned object is achieved by forming a photosensitive layer 2 containing at least one of the bisazo compounds represented by the general formula (1).
Having A, 2B, 2C, Cp-N=N-person+C)
1=C)1+-rC)I=N-B-N=CII(CH=
C) IhA-N=N-Cp・CI) [In general formula (1), A is an aromatic heterocyclic group, B is a single bond, an aryl group, a heterocyclic group, or a bond thereof, and n is 0
．． 1 or 2, cp is a general formula (old.

It is a coupler residue represented by (111), (■) or (V).

In formulas (11) to (V), Z is a residue that is fused with a benzene ring to form a polycyclic aromatic ring or a heterocycle;
R+l again;! NR, L (R,, R2 and R, hydrogen atom, each representing an optionally substituted alkyl group, aryl group or aromatic heterocyclic group), X2 and X,
each represents an optionally substituted alkyl group, aryl group, or aromatic heterocyclic group, x3 and X@ represent a hydrogen atom, cyano group, carbamoyl group, carboxyl group, ester group, or acyl group, and Indicates a hydrogen atom, an optionally substituted alkyl group, cycloalkyl group, alkenyl group, aryl group, or aromatic heterocyclic group,
X and X are a hydrogen atom and a halogen atom, respectively.

represents a nitro group, an optionally substituted alkyl group, or an alkoxy group, Xs represents an alkyl group, an aryl group, or a carboxyl group, and Xll represents an optionally substituted aryl group or an aromatic heterocyclic group. ] is achieved.

The bisazo compound represented by formula (1) is synthesized as follows. Amine H2N-B-N)1. and aldehyde O,N-^+CH=CH), C8 are condensed according to the reaction formula (Vl), and the obtained dinitro compound is reduced to form a diamine as a raw material according to the reaction formula (■))1. N-B-Nil, + 202N-^(
C) l=cH), CHO-O, NA-4CI=CH
)-vcH=N-B-N=CH+CH=CH)rA-N
mouth.

(Vl) OJ-A4C)1=cHhcH=N-8-N=C)l(
CH=C)IhA-NO*→H,N-A4C)1=c)
1h['H=N-B-N=CH4C)I=CH)-A-
Nll.

(■) The obtained diamine is diluted with nitrous acid using a conventional method.
2-A4CIl=C)l)tcH=N -B-N=C
H+Cl1=CH)i-A-N2 ] ” 2 Cj
F-1 (■) The obtained tetrazonium salt is mixed with a coupler and a suitable solvent,
For example, the bisazo compound of general formula (1) can be obtained by a coupling reaction in N,N-dimethylformamide (DMF) with a base (such as acetate).

Shown in the table.

・(IX) R4 in the above formula.

R3゜ R@T n.

cp is as below be.

(X) In the above formula R0~Rl 3 + n.

Cp is as follows.

・　　　(XI) In the above formula, R14 to R8°.

n.

Cp is as follows.

In the above formula R2+-R23+ n.

cp is as follows.

(XI) In the above formula R + s + R2゜.

n.

Cp is as follows.

(shop) In the above formula, R24 to R□.

n.

Cp is as follows.

(Xff) The photoreceptor of the present invention contains a bisazo compound represented by the general formula (1) in the photosensitive layer. Alternatively, it can be used as shown in FIG.

1 to 3 are conceptual cross-sectional views of the photoreceptor of the present invention.
2A, 2B, and 2C are photosensitive layers; 3 is a charge-generating material; 4 is a charge-generating layer; 5 is a charge-transporting material; 6 is a charge-transporting layer; and 7 is a coating layer.

FIG. 1 shows a photosensitive layer 2A in which a bisazo compound as a charge generating substance 3 and a charge transporting substance 5 are dispersed in a resin binder on a conductive substrate 1 (a structure usually referred to as a single-layer photoconductor).
is provided.

FIG. 2 shows a charge generation layer 4 containing a bisazo compound as a charge generation substance 3 and a charge transport substance 5 on a conductive substrate 1.
A photosensitive layer 2B consisting of a laminated layer with a charge transport layer 6 mainly composed of
(a configuration commonly referred to as a laminated photoreceptor).

FIG. 3 shows a layer structure opposite to that of FIG. 2 (photosensitive layer 2).
C).

The reason for the layer configurations shown in FIGS. 2 and 3 is that the layer configuration shown in FIG. 2 is usually used as a negative charging system. Second
Even if an attempt is made to use the layer structure shown in the figure in a positive charging system, the current situation is that no charge transport material compatible with this has been found. Therefore, the layer structure shown in FIG. 3 can be used as a positive charging type photoreceptor, as already proposed by the present inventors.

The photoreceptor shown in FIG. 1 can be produced by dispersing a charge generating material in a solution containing a charge transporting material and a resin binder, and applying this dispersion onto a conductive substrate.

The photoreceptor shown in Figure 2 is made by coating a conductive substrate with a dispersion obtained by dispersing particles of a charge-generating substance in a solvent or a resin binder, drying it, and then dissolving a charge-transporting substance and a resin binder thereon. Apply solution.

It can be produced by drying.

The photoreceptor shown in Figure 3 is made by coating a conductive substrate with a solution containing a charge transport substance and a resin binder.

After drying, a dispersion obtained by dispersing charge-generating substance particles in a solvent or resin binder is applied on top.

It can be produced by drying.

The conductive substrate 1 serves as an electrode for the photoreceptor and at the same time serves as a support for other layers, and may be cylindrical, plate-shaped, or film-shaped, and may be made of metal such as aluminum, stainless steel, or nickel. Alternatively, it may be made of glass, resin, or the like and subjected to conductive treatment.

The charge generation layer 4 is formed by applying a material in which particles of the charge generation substance 3 made of a bisazo compound represented by the general formula (I) are dispersed in a resin binder, and generates charges by receiving light. do. In addition to the high charge generation efficiency, the ability to inject the generated charges into the charge transport layer 6 and the coating layer 7 is also important, and it is desirable that the charge is less dependent on the electric field and can be easily injected even in a low electric field. The charge generation layer is mainly composed of a charge generation substance, and a charge transport substance or the like may be added thereto. Resin binders include polycarbonate, polyester, and polyamide.

Polyurethane, epoxy 1 silicone resin, methacrylic acid ester polymers, copolymers, and the like can be used in appropriate combinations.

The charge transport layer 6 is formed by applying a material in which a hydrazone compound, a pyrazoline compound, a styryl compound, a triphenylamine compound, an oxazole compound, an oxadiazole compound, etc. are dissolved and dispersed as an organic charge transport substance in a resin binder. In the dark, it functions as an insulating layer to hold the charge on the photoreceptor, and when receiving light, it functions to transport the charge injected from the charge generation layer. As a resin binder, polycarbonate, polyester, polyamide,
Polyurethane, epoxy resin, silicone resin, methacrylic acid ester polymers and copolymers, etc. can be used.

The coating layer 7 has the function of receiving and retaining the charge of corona discharge in a dark place, and has the ability to transmit the light to which the charge generation layer is sensitive, and transmits the light upon exposure, and the charge generation layer It is necessary for the surface charge to be neutralized and annihilated by the injection of the generated charge. As the coating material, organic insulating film-forming materials such as polyester and polyamide can be used. In addition, these materials and glass resin, 5i
It is also possible to use a mixture of inorganic materials such as 02 and materials that reduce electrical resistance such as metals and metal oxides. The coating material is not limited to organic insulating film forming materials (it is also possible to form inorganic materials such as 5i02, metals, metal oxides, etc. by methods such as vapor deposition and sputtering. As described above, it is desirable that the charge generating material be as transparent as possible in the wavelength region where the light absorption is maximum.

The thickness of the coating layer itself depends on the composition of the coating layer, but
It can be set arbitrarily within a range that does not cause adverse effects such as an increase in residual potential when used repeatedly and continuously.

[Effect]

There is no known example in which a bisazo compound represented by the general formula (1) is used in a photosensitive layer. In order to achieve the above objective, the present inventors conducted numerous experiments on these bisazo compounds while conducting intensive studies on various organic materials. We have discovered that the use of a specific bisazo compound represented by formula (1) above as a charge-generating substance is extremely effective in improving electrophotographic properties, and we have developed a photoreceptor with high sensitivity and excellent repeatability. I ended up getting it.

〔Example〕

Examples of the present invention will be described below.

Example 1 50 parts by weight of the bisazo compound represented by Compound 1 was added to a polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.)
100 parts by weight and 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-
A coating solution was prepared by kneading 100 parts by weight of 2-pyrazoline (A S P P) and a tetrahydrofuran (THF) solvent in a mixer for 3 hours, and the coating solution was coated on an aluminum-deposited polyester film (^J-PET) as a conductive substrate. A photoreceptor was prepared by coating the film using a wire bar method so that the film thickness after drying was 15 μm.

Example 2 First, a solution prepared by dissolving 100 parts by weight of p-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) in 700 parts by weight of tetrahydrofuran (THF) and a polycarbonate resin (trade name Panlite L-1) were prepared.
A coating solution prepared by mixing 100 parts by weight of 250 (manufactured by Ondai) with a solution obtained by dissolving 700 parts by weight of a 1:1 mixed solvent of THF and dichloromethane was applied onto an aluminum-deposited polyester film substrate using a wire bar method. The film thickness after drying is 15
A charge transport layer was formed to have a width of μ. On the thus obtained charge transport layer, 50 parts by weight of the bisazo compound represented by the compound Nα1, 50 parts by weight of polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.), and 50 parts by weight of PMMA
Parts by weight and a THF solvent were kneaded in a mixer for 3 hours to prepare a coating solution, which was coated by a wire bar method to form a charge generation layer so that the film thickness after drying was 0.5 μm.

Example 3 In Example 2, the charge transport substance was changed to ABPH, and the styryl compound α-phenyl-4°-N,N
A charge transport layer was formed using -dimethylaminostilbene in the same manner as in Example 2, and a charge generation layer was further formed to produce a photoreceptor.

Example 4 In Example 2, the charge transport substance was changed to ABPH and was replaced with a triphenylamine compound, TO! A charge transport layer was formed using J(p-tolyl)amine in the same manner as in Example 2, and a charge generation layer was further formed to produce a photoreceptor.

Example 5 In Example 2, the charge transport substance was replaced with ABPH and an oxadiazole compound, 2°5-bis(p-
A charge transport layer was formed using (diethylaminophenyl)-1,3°4-oxadiazole in the same manner as in Example 2, and a charge generation layer was further formed to prepare a photoreceptor.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester [r SP-428J manufactured by Kawaguchi Electric. The results are shown in Table 1.

The surface potential V s (volts) of the photoreceptor is +6.
This is the initial surface potential when QkV corona discharge is performed for 10 seconds to positively charge the surface of the photoreceptor, and the surface potential Vd (volts) when the photoreceptor surface is then held in the dark for 2 seconds with corona discharge stopped. The photoreceptor surface was then irradiated with white light with an illuminance of 2 lux, and the time (seconds) required for V to be halved was determined to be the half-attenuation exposure amount EI/2 (lux seconds). Further, the surface potential when white light with an illuminance of 2 lux was irradiated for 10 seconds was defined as the residual potential V (volt).

As seen in Table 1, Examples 1, 2, 3, 4 and 5 had good half-attenuation exposure and residual potential.

Example 6 100 parts by weight of the above compound N (bisazo compound represented by 12 to Na70) was kneaded with 100 parts by weight of a polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.) and a THF solvent for 3 hours using a blender to form a coating solution. Prepare,
Each charge generation layer was formed by coating on an aluminum support to a thickness of about 0.5 μm.

A coating liquid containing ASPP as a charge transport substance obtained by the same method as in Example 2 was applied onto this to a thickness of about 15 μm to prepare a photoreceptor.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester RSP-428J manufactured by Kawaguchi Electric. The results are shown in Table 2.

A corona discharge of -5.9 kV was applied to the surface of the photoreceptor in a dark place for 10 minutes.
The surface potential VD (volts) was measured when the photoreceptor surface was negatively charged for 2 seconds, then maintained in the dark for 2 seconds with corona discharge stopped, and then white light with an illuminance of 2 lux was irradiated onto the surface of the photoreceptor. time until Vd becomes half (seconds)
was determined, and the half-attenuation exposure amount was determined as El/2 (lux/second).

Further, the surface potential when white light with an illuminance of 2 lux was irradiated for 10 seconds was defined as the residual potential V, (volt). The results are shown in Table 2.

Table 2 (Part 2) Table 2 (Part 3) Table (Part 4) 1 Conductive substrate, 2A, 2B, 2C photosensitive layer 3 Charge generation substance, 4 Charge generation layer, 5 Charge transport substance, 6 Charge transport Layer, 7 Covering layer.

Table (No. 5) [Effects of the Invention] According to the present invention, since the bisazo compound represented by formula (1) is used as a charge generating substance on a conductive substrate, the bisazo compound represented by formula (1) can be easily charged even in positive and negative charging. A photoreceptor with high sensitivity and excellent repeatability can be obtained.

Furthermore, if necessary, a coating layer can be provided on the surface to improve durability.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are conceptual cross-sectional views showing different embodiments of the photoreceptor of the present invention. Figure Figure Figure

Claims (1)

[Scope of Claims] 1) An electrophotographic photoreceptor comprising a photosensitive layer containing at least one bisazo compound represented by general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(I) [In the general formula (I), A is an aromatic heterocyclic group, B is a single bond, an aryl group, a heterocyclic group, or a bond thereof, and n is 0, 1 or 2, Cp is a general formula (II), (III), (IV
) or (V). ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (III) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (IV) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( V) In formulas (II) to (V), Z is a residue that is fused with a benzene ring to form a polycyclic aromatic or heterocycle, and X_1 is O
R_1 or NR_2R_3 (R_1, R_2 and R
_3 represents a hydrogen atom, each optionally substituted alkyl group, aryl group or aromatic heterocyclic group), X_
2 and X_5 each represent an optionally substituted alkyl group, aryl group or aromatic heterocyclic group, and X_3
and X_5 is a hydrogen atom, a cyano group, a carbamoyl group,
Represents a carboxyl group, ester group or acyl group, X
_4 represents a hydrogen atom, an optionally substituted alkyl group, cycloalkyl group, alkenyl group, aryl group, or aromatic heterocyclic group, and X_7 and X_8 each represent a hydrogen atom, a halogen atom, a nitro group, or an unsubstituted X_9 represents an alkyl group, an aryl group, or a carboxyl group, and X_1_
0 represents an optionally substituted aryl group or aromatic heterocyclic group. ]