JPH01159659A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body for use in copying machines and printers having high sensitivity and superior repetition characteristics by forming a photosensitive layer containing a specified hydrazone compound. CONSTITUTION:The photosensitive layer contains at least one of the hydrazone compounds represented by formula I in which each of R1-R7 is H, halogen, alkyl, alkoxy, hydroxy, nitro, acyl, optionally substituted aryl, or amino; R8 is optionally substituted aryl; each of l and m is 1, 2, or 3; and n is 0 or 1, thus permitting the obtained photosensitive body to be high in sensitivity in both cases of positive and negative charging and superior in repetition characteristics.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, it is characterized in that a novel hydrazone compound is contained in a photosensitive layer formed on a conductive substrate. The present invention relates to a photoreceptor for electrophotography.

[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. Dispersions, organic photoconductive materials such as poly-N-vinyl carbazole or polyvinyl anthracene, organic photoconductive materials such as phthalocyanine compounds or bisazo compounds dispersed in resin binders or vacuum evaporated. and other items are being used.

The photoreceptor also has the ability to retain surface charge in the dark.

It is necessary to have the function of receiving light and generating a charge, as well as the function of receiving light and transporting a charge, but there is a so-called single fan type photoreceptor that has both of these functions in one layer, and a function that mainly generates a charge. There is a so-called laminated photoreceptor in which functionally separated layers are laminated, including a layer that contributes to charge generation, a layer that contributes to surface charge retention in the dark, and a layer that contributes to charge transport during light reception. 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 electrostatic latent images such as letters and pictures on the document by exposing the surface of the charged photoconductor, and This is done by developing a latent image with toner and fixing the developed toner image on a support such as paper.
After the toner image has been transferred, the photoreceptor is subjected to static electricity removal, residual toner removal, optical static electricity removal, etc., and is then reused.

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-vinyl carbazole and 2
．． 4.7-)'J nitrofluorene-9-one (described in U.S. Pat. No. 3,484,237)
, Photoreceptor containing organic pigment as main component JP-A-47-375
43 (described in Japanese Patent Application Laid-Open No. 1987-10735), and a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (described in Japanese Patent Application Laid-open No. 10735/1983). Furthermore, many new hydrazone compounds have also been put into practical use.

[Problem that the invention seeks to solve]

As mentioned above, organic materials have many advantages that inorganic materials do not have, but at the same time, there is currently no material that fully satisfies all the characteristics required of electrophotographic photoreceptors. In particular, there were problems with photosensitivity and characteristics during repeated and continuous use.

The present invention has been made in view of the above points, and by using a new organic material that has never been used as a charge transport material in the photosensitive layer, a copying machine with high sensitivity and excellent repeatability can be achieved. The purpose of the present invention is to provide an electrophotographic photoreceptor for use in cameras and printers.

[Means for solving problems]

In order to achieve the above object, the present invention provides an electrophotographic photoreceptor having a photosensitive layer containing at least one type of hydrazone compound represented by the following general formula (1).

[In formula (1), R1, R2, R3, R4, R8, R1 and R1 are each a hydrogen atom, a halogen atom, an alkyl group, a hydroxy group, an alkoxy group, a nitro group, an acyl group, an optionally substituted aryl group , represents an amino group, and R6
represents an optionally substituted aryl group. Also,! and m represent any one of the three integers of 1.2 and 3, respectively, and n represents either 0 or 1. ] [Function] There is no known example in which a hydrazone compound represented by the above general formula (1) is used in a photosensitive layer. In order to achieve the above object, the present inventors conducted a number of experiments on these hydrazone compounds while conducting intensive studies on various organic materials. We have discovered that the use of a specific hydrazone compound represented by the above general formula (1) as a charge transport material 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〕

The hydrazone compound of the general formula (1) used in the present invention can be synthesized by a conventional method. That is, it can be obtained by condensing aldehydes or carbonyl compounds with hydrazines in a suitable organic solvent such as alcohol, using a small amount of acid as a condensing agent if necessary.

Specific examples of the hydrazone compound represented by the general formula (1) thus obtained are as follows.

N95 Compound 7 Compound 11 Sitting 20 Compound N921 Clothes 22 to 30 Compound dust 31 Compound tooth 36 Compound 45 Compound right 51 The photoreceptor of the present invention contains the above-mentioned hydrazone compound in the photosensitive layer. Figure 1 shows how these hydrazone compounds are applied.

It can be used as shown in FIG. 2 or 3.

1 to 3 are conceptual cross-sectional views of the photoreceptor of the present invention.
20, 21 and 22 are a conductive substrate, 20, 21 and 22 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 20 (commonly referred to as a single-layer photoreceptor) in which a charge generating substance 3 and a hydrazone compound as a charge transporting substance 5 are dispersed in a resin binder on a conductive substrate 1. ) is provided.

FIG. 2 shows a photosensitive layer 2 formed by laminating a charge generation layer 4 mainly containing a charge generation substance 3 and a charge transport layer 6 containing a hydrazone compound as a charge transport substance 5 on a conductive substrate 1.
1 (a configuration commonly referred to as a laminated photoreceptor).

FIG. 3 shows an inverse layer configuration to that of FIG.

In this case, it is common to further provide a coating layer 7 to protect the charge generation layer 4.

The reason for the two types of layer configurations shown in Figures 2 and 3 is that even if the layer configuration shown in Figure 2, which is normally used for a negative charging system, is intended to be used for a positive charging system, there is no compatible charge transport material. This is because it has not been found yet, and therefore, at this stage, it is necessary to form a photoreceptor with the layer structure shown in FIG.

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 produced by vacuum-depositing a charge-generating substance on a conductive substrate, or by coating and drying a dispersion obtained by dispersing particles of a charge-generating substance in a solvent or resin binder, and then It can be produced by applying a solution containing a charge generating substance and a resin binder to the surface of the substrate and drying it.

The photoreceptor shown in Figure 3 is produced by coating a conductive substrate with a solution containing a charge transporting substance and a resin binder and drying it, and then vacuum-depositing a charge generating substance thereon, or by depositing charge generating substance particles in a solvent or a solvent. It can be produced by applying a dispersion obtained by dispersing it in a resin binder, drying it, and further forming a coating layer.

The conductive substrate l serves as an electrode for the photoreceptor and at the same time serves as a support for the other layers, and may be cylindrical, plate-shaped, or film-shaped, and may be made of aluminum, stainless steel, nickel, etc. It may also be made of metal, glass, resin, or the like, which has been subjected to conductive treatment.

The charge generation layer 4 is formed by applying a material in which charge generation substance 30 particles are dispersed in a resin binder as described above, or by a method such as vacuum deposition, and generates charges by receiving light. In addition, the charge transport layer 6 and the coating layer 7 for the generated charges at the same time have a high charge generation efficiency.
It is important to have good injection properties even in low electric fields with little dependence on electric fields. Examples of the charge generating substance include phthalocyanine compounds such as metal-free phthalocyanine and titanyl phthalocyanine, various azo, quinone, and indigo pigments, or cyanine and squarylium.

Dyes such as azulenium and pyrylium compounds, selenium or selenium compounds, and the like are used, and suitable substances can be selected depending on the light wavelength range of the exposure light source used for image formation. 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, and a charge transport substance or the like may be added thereto.

As the resin binder, polycarbonate, polyester, polyamide, polyurethane, epoxy, silicone resin, polymers and copolymers of methacrylic acid ester, etc. can be used in appropriate combinations.

The charge transport layer 6 is a coating film in which a hydrazone compound represented by formula (I) as an organic charge transport substance is dispersed in a resin binder, and serves as an insulating layer in the dark to retain the charge on the photoreceptor and to During reception, it functions to transport charges injected from the charge generation layer. As the resin binder, polycarbonate, polyester, polyamide, polyurethane, epoxy, silicone resin, polymers and copolymers of methacrylic acid ester, 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 to neutralize and eliminate the surface charges by injecting the generated charges. As the coating material, organic insulating film-forming materials such as polyester and polyamide can be used. In addition, these organic materials and glass resin, 5
It is also possible to use a mixture of inorganic materials such as i02 and materials that reduce electrical resistance such as metals and metal oxides. The coating material is not limited to organic insulating film-forming materials, and inorganic materials such as Sin, metals, metal oxides, etc. can also be formed by methods such as vapor deposition and sputtering. As mentioned above, it is desirable that the coating material be as transparent as possible in the wavelength region where the charge generating substance absorbs maximum light.

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.

Examples of the present invention will be described below.

Example 1 A polyester resin (
A coating solution was prepared by kneading 100 parts by weight (trade name: Vylon 200: manufactured by Toyobo) with a tetrahydrofuran (THF) solvent for 3 hours in a mixer, and then coated on an aluminum-deposited polyester film (^f-PET), which is a conductive substrate. A photosensitive layer was formed by coating using a wire bar method so that the film thickness after drying was 15 μm, and a photosensitive member having the structure shown in FIG. 1 was prepared.

Example 2 First, α-type metal-free phthalocyanine was used as a starting material, and while two linear motors were placed facing each other, α-type metal-free phthalocyanine and a nonmagnetic separation body containing a Teflon-coated magnetic piece as a working piece were mixed. The powder was pulverized for 20 minutes using an electromagnetic pulverizer (trade name: LIMMAC, manufactured by Fuji Electric). 1 part by weight of this finely powdered sample c! -50 parts by weight of DMF (N,N-dimethylformamide) solvent was subjected to ultrasonic dispersion treatment. Thereafter, the sample and DMF were separated and filtered, dried, and treated for metal-free phthalocyanine.

Next, a hydrazone compound 1 represented by the above compound Nα2
00 parts by weight dissolved in 700 parts by weight of tetrahydrofuran (THF) and polymethyl methacrylate polymer (P
MMA: manufactured by Tokyo Kasei Co., Ltd.) 100 parts by weight to 700 parts by weight of toluene
A coating solution prepared by mixing parts by weight of the solution was coated onto an aluminum-deposited polyester film substrate by a wire bar method to form a charge transport layer so that the film thickness after drying was 15 μm. On the charge transport layer thus obtained, 50 parts by weight of the above-treated metal-free phthalocyanine, 5 parts of polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.),
0 parts by weight, 50 parts by weight of PMMA with THF solvent
A coating solution was prepared by kneading with a time mixer, and applied using a wire bar method to form a charge generation layer with a film thickness of 1 μm after drying. The body was created.

Example 3 The composition of the photosensitive layer of Example 1 was changed to 50% metal-free phthalocyanine.
Part by weight, hydrazone compound 10 represented by compound Nα3
0 parts by weight, polyester resin (trade name Byron 200:
A photosensitive layer was formed in the same manner as in Example 1 except that 50 parts by weight of PMMA (manufactured by Toyobo Co., Ltd.) and 50 parts by weight of PMMA were used to prepare a photoreceptor.

Example 4 In Example 3, a photosensitive layer was formed in the same manner as in Example 1 using chlorodiane blue, which is a bisazo pigment as disclosed in JP-A-47-37543, instead of metal-free phthalocyanine, to produce a photoreceptor. did.

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

The surface potential V, (volt) of the photoreceptor is +6.0kV in the dark.
This is the initial surface potential when corona discharge is performed for 10 seconds to positively charge the surface of the photoreceptor, and the surface potential V is the surface potential when the photoreceptor surface is then held in the dark for 2 seconds with corona discharge stopped.
(volts, ), and then irradiate the surface of the photoconductor with white light with an illuminance of 2 lux to find the time (seconds) until vd is halved.
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). In addition, when a phthalocyanine compound is used as a charge generating substance, high sensitivity with long wavelength light can be expected.
Electrophotographic properties using 0 nm monochromatic light were also measured at the same time. That is, measurements are made in the same manner up to Vd, then 1 μW monochromatic light (780 nm) is irradiated instead of white light to determine the half-attenuation exposure amount (μJ/cd), and this light is applied to the photoreceptor surface for 10 seconds. Residual potential V, (
Volts) were measured. The measurement results are shown in Table 1.

As seen in Table 1, Examples 1 and 2.3°4 are comparable in half-attenuation exposure and residual potential, and also exhibit good characteristics in terms of surface potential.

Further, it can be seen that Examples 1.2.3 in which a phthalocyanine compound was used as the charge generating substance showed high sensitivity even with long wavelength light of 780 nm, and could be sufficiently used for semiconductor laser printers.

Example 5 Selenium was deposited to a thickness of 1 on a 500 μm thick aluminum plate.
．． A charge generating layer was formed by vacuum evaporation on 5μ..., and then a solution obtained by dissolving 100 parts by weight of a hydrazone compound represented by compound Nα4 in 700 parts by weight of tetrahydrofuran (THF) and polymethyl methacrylate polymer (PMMA:
A coating liquid made by mixing 100 parts by weight of 100 parts by weight (manufactured by Tokyo Kasei) in 700 parts by weight of toluene is applied using the wire bar method to form a charge transport layer so that the film thickness after drying is 20 μm. Then, a photoreceptor having the configuration shown in FIG. 2 was produced.

When this photoreceptor was corona charged at -6.0 kV for 0.2 seconds, V = -630V.

Good results were obtained with Vr''-50V and EIy*=5.3 lux·sec.

Example 6 50 parts by weight of the metal-free phthalocyanine treated in Example 1, 50 parts by weight of polyester resin (trade name Byron 200, manufactured by Toyobo), and 50 parts by weight of PMMA were kneaded with a THF solvent in a mixer for 3 hours to prepare a coating solution. The mixture was adjusted and coated on an aluminum support to a thickness of about 1 μm to form a charge generation layer. Next, 100 parts by weight of a hydrazone compound represented by compound Nα5, 100 parts by weight of polycarbonate resin (Panlite L-1250), and 0 parts by weight of silicone oil were added.
．． 1 part by weight was mixed with 700 parts by weight of THF and 700 parts by weight of toluene, and the mixture was applied onto the charge generation layer in an amount of about 15 μl to form a charge transport layer.

The photoreceptor thus obtained was corona charged at -6,0kV for 0.2 seconds in the same manner as in Example 5, Vm = -660V, El/2 = 4.9 Lua.
Good results were obtained.

Example 7 Photosensitive layers were prepared in the same manner as in Example 4 for each of the compounds Nα6 to Nα60 and measured using rSP-4284. The results are shown in Table 2. This result is +5. Q
Perform kV corona discharge for 10 seconds to make it positively charged, and set the illumination intensity to 2.
Half-attenuation exposure amount E+/ when irradiated with Lux white light
It is expressed as 2 (looks/second).

Table 2 (Part 1) Table 2 (Part 2) As seen in Table 2, the hydrazone compound Nα6
The half-attenuation exposure amount E1/2 was also good for the photoreceptor using ~MO,60 as the charge transport material.

〔Effect of the invention〕

According to the present invention, since the hydrazone compound represented by the general formula (I) is used as a charge transport material on the conductive substrate, the photoreceptor is highly sensitive even when positively charged and negatively charged, and has excellent repeatability. can be obtained. In addition, a suitable charge-generating substance can be selected depending on the type of exposure light source; for example, by using phthalocyanine compounds and certain bisazo compounds, a photoreceptor that can be used in semiconductor laser printers can be obtained. be able to. Furthermore, if necessary, it is possible to provide a coating layer on the surface to improve durability.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are conceptual sectional views showing different embodiments of the photoreceptor of the present invention. 1 conductive substrate, 3 charge generation substance, 4 charge generation layer,
5 charge transport material, 6 charge transport layer, 7 coating layer, 20.
21.22 Photosensitive layer. ] 2nd Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1) An electrophotographic photoreceptor comprising a photosensitive layer containing at least one type of hydrazone compound represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・・・
...(I) [In formula (I), R_1, R_2, R_3, R_4, R
_5, R_6 and R_7 each represent a hydrogen atom, a halogen atom, an alkyl group, a hydroxy group, an alkoxy group, a nitro group, an acyl group, an optionally substituted aryl group, or an amino group, and R_8 is an optionally substituted aryl group represents. Furthermore, l and m each represent any one of three integers, 1, 2, and 3, and n represents either 0 or 1. ]