JPH01170946A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve sensitivity and repetitive characteristics by incorporating a specific hydrazone compd. into a photosensitive layer. CONSTITUTION:The hydrazone compd. expressed by formula (I) is incorporated as a charge transfer material into the photosensitive layer. In formula, R1-R4 denote any of a hydrogen atom., halogen, atom., alkyl group, hydroxy group, alkoxy group, allyl group, aryl group, acyl group or nitro group; (m), (n) denote either of 0 and 1. The photosensitive body which has the high sensitivity in both positive and negative electrostatic charge and the excellent repetitive characteristics is thereby obtd.

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) include 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-vinylcarbazole or polyvinylanthracene, organic photoconductive materials such as phthalocyanine compounds or bisazo compounds dispersed in a resin binder or vacuum deposited. etc. are used.

In addition, a photoreceptor must 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, all of which can be achieved in one layer. A so-called single-layer photoreceptor with the following functions is laminated with functionally separated layers: a layer that mainly contributes to charge generation, and a layer that contributes to surface charge retention in the dark and charge transport during light reception. There is a so-called laminated photoreceptor. 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 is transferred, the photoreceptor is subjected to static neutralization, residual toner removal, photostatic static elimination, etc., and then it is reused. served.

In recent years, flexibility 1. Electrophotographic photoreceptors using organic materials have been put into practical use due to their advantages such as thermal stability and film-forming properties. For example, poly-N-vinylcarbazole and 2
．． 4.7-) dinitrofluorene-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 hydrazone compounds have also been put into practical use.

[Problem that the invention seeks to solve]

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.

An object of the present invention is to provide an electrophotographic photoreceptor for copying machines and printers that has high sensitivity and excellent repeatability.

[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), R+, R2, R3 and R1 each represent a hydrogen atom, a halogen atom, an alkyl group, a hydroxy group, an alkoxy group, an allyl group, an aryl group, an acyl group or a nitro group, m, n represents either 0 or 1, respectively. [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. It has been 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 a photoreceptor with high sensitivity and excellent repeatability has been developed. I was able to obtain this.

〔Example〕

The hydrazone compound of general formula (I) used in the present invention can be synthesized by a conventional method. That is, it can be obtained by condensing aldehydes and 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 (I) thus obtained are as follows.

H3 The photoreceptor of the present invention contains the above-described hydrazone compound in the photosensitive layer.

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 (usually 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. configuration) 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 in 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 you try to use the layer configuration in Figure 2, which is normally used for a negative charging system, in 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 create 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 transporting substance and a resin binder to the surface of the substrate and drying the solution.

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 1 serves as an electrode of 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 aluminum, stainless steel, nickel (D) 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 particles of the charge generation substance 3 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. As the charge generating substance, metal-free phthalocyanine, phthalocyanine compounds such as titanyl phthalocyanine, various azo, quinone, indigo pigments, or cyanine 1-squarylium.

Dyes such as azulenium and biryllium 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 the maximum (I) above is dispersed as an organic charge transport substance in a resin binder, and serves as an insulating layer in the dark to retain the charge on the photoreceptor and prevent light from entering. 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 an inorganic material such as in2, or a material that reduces electrical resistance such as a metal or metal oxide. The coating material is not limited to organic insulating film forming materials (inorganic materials such as Sin, metals, metal oxides, etc. can also be formed by methods such as vapor deposition and sputtering.Coating materials As mentioned above, it is desirable that ε be as transparent as possible in the wavelength range of maximum light absorption of the charge generating material.

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 50 parts by weight of metal-free phthalocyanine (Tokyo Kasei! 11) ground for 150 hours in a ball mill and 100 parts by weight of the hydrazone compound represented by Compound No. 1 were mixed into a polyester resin (trade name Byron 200: Toyobo! II) 100 parts by weight
3 parts by weight with tetrahydrofuran (THF) solvent
A coating solution was prepared by kneading with a time mixer, and aluminum-deposited polyester film (A J-P
A photosensitive layer was formed on E T ) by a wire bar method so that the film thickness after drying was 15 μm, thereby producing a photoreceptor having the structure shown in FIG. 1.

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 mixture was pulverized for 20 minutes using an electromagnetic pulverizer (trade name: LIMMAC, manufactured by Fuji Electric) for pulverization. 1 part by weight of this finely powdered sample and 50 parts by weight of DMF ('N,N-dimethylformamide) solvent were subjected to ultrasonic dispersion treatment. Thereafter, the sample and DMF were separated and filtered, dried, and treated for metal-free phthalocyanine.

Next, 100 parts by weight of the hydrazone compound represented by Compound No. 2 was added to 700 parts by weight of tetrahydrofuran (THF).
7 parts by weight of the solution and 100 parts by weight of polymethyl methacrylate polymer (PMMA: manufactured by Tokyo Kasei) were mixed with 7 parts by weight of toluene.
A coating solution prepared by mixing a solution of 0.00 parts by weight was applied onto an aluminum vapor-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, 50 parts by weight of polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.), and 50 parts by weight of PMM A were added together with a THF solvent. A coating solution was prepared by kneading with a mixer for 3 hours,
A charge generation layer was formed by coating using a wire bar method so that the film thickness after drying was 1 μm, and a photoreceptor having the structure shown in FIG. 3 was prepared.

Example 3 The composition of the photosensitive layer of Example 1 was changed to 50% metal-free phthalocyanine.
Parts by weight, Compound No. 100 parts by weight of a hydrazone compound represented by 3, Polyester resin (trade name: Vylon 20)
A photosensitive layer was formed in the same manner as in Example 1 except that 50 parts by weight of PMMA 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, for example, a chlorodiapolymer, which is a bisazo pigment as disclosed in JP-A-47-37543, instead of metal-free phthalocyanine, and a photoreceptor was formed. Created.

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 (volts) of the photoreceptor is +6. OkV
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 Vd is then maintained in the dark for 2 seconds with corona discharge stopped.
(volts), and then the illuminance 2 on the photoreceptor surface.
Calculate the time (seconds) it takes for V to be halved after irradiating the lux white light, and find the half-attenuation exposure amount E1/2 (lux seconds)
And so. Also, the surface potential when irradiated with white light with an illuminance of 2 lux for 10 seconds is the residual potential V? (volt).

In addition, when a phthalocyanine compound is used as a charge generating substance, high sensitivity can be expected with long wavelength light, so the wavelength is 780 nm.
At the same time, electrophotographic characteristics were measured using m monochromatic light. That is, measurements are carried out in the same manner up to ■, then 1 μW monochromatic light (780 nm) is irradiated instead of white light to determine the half-attenuation exposure amount (μJ/crl), and this light is
The residual potential V, (volt) when the surface of the photoreceptor was irradiated for a second was measured. The measurement results are shown in Table 1.

As seen in Table 1, Examples 1, 2, and 3°4 are comparable in half-attenuation exposure and residual potential, and also exhibit good characteristics in terms of surface potential. Furthermore, Examples 1 and 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 it was found that they 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 generation layer was formed by vacuum evaporation to a thickness of 5 μm, and then a solution prepared by dissolving 100 parts by weight of a hydrazone compound represented by Compound No. 4 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. and is shown in Figure 2.

A photoreceptor with the following configuration was manufactured. When this photoreceptor was corona charged at -6, OkV for 0.2 seconds, V, = -60
0V.

Good results were obtained with Vr=-60V and El/2=4Jlux·sec.

Example 6 50 parts by weight of metal-free phthalocyanine treated in Example 1, polyester resin (trade name Byron 200: Toyobo!)
A coating solution was prepared by kneading 50 parts by weight of No. 11 and 50 parts by weight of PMMA with a THF solvent in a mixer for 3 hours, and the coating solution was 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 and a polycarbonate resin (
Panlite L-1250) 100 parts by weight, 0.1 parts by weight of silicone oil, 700 parts by weight of THF and 700 parts by weight of toluene.
They were mixed in parts by weight and coated on the charge generation layer to a thickness of about 15 μm to form a charge transport layer.

When the photoreceptor thus obtained was corona charged at -6.0 kV for 0.2 seconds in the same manner as in Example 5, V- = -620 V, E l/2 = 5.9 Lux. Good results were obtained in seconds.

Example 7 Example 4 for each of compounds Nα6 to No. 18
In the same manner as above, a photosensitive layer was formed, a photoreceptor was prepared, and rSP-42
Table 2 shows the results of the measurements using ``No. 8''. This result was expressed as a half-attenuation exposure amount E 1/2 (lux seconds) when the sample was positively charged by performing corona discharge at +6.0 kV for 10 seconds in a dark place and then irradiated with white light at an illuminance of 2 lux.

Table 2 (Part 1) As seen in Table 2, the hydrazone compound No.
The half-attenuation exposure 'IE1y2 was also good for the photoreceptors using 5 to Nα18 as charge transport materials.

〔Effect of the invention〕

According to the present invention, since the hydrazone compound represented by -maximum (I) is used as a charge transport material on a conductive substrate, a photoreceptor with high sensitivity and excellent repeatability even in positive and negative charging can be obtained. 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.

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 and R_4
each represents a hydrogen atom, a halogen atom, an alkyl group, a hydroxy group, an alkoxy group, an allyl group, an aryl group, an acyl group, or a nitro group, and m and n each represent either 0 or 1. ]