JPH01152467A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and repetition characteristics by forming a photosensitive layer containing at least one of specified hydrazone compounds. CONSTITUTION:The photosensitive layer formed on a conductive substrate contains as an electric charge transfer material at least one of the hydrazone compounds represented by formula I and II in which each of R1, R2, R3 and R6 is H, halogen, alkyl, alkoxy, hydroxy, allyl, nitro, optionally substituted aryl, or amino; each of R4 and R5 is optionally substituted aryl; n is 1 or 2, and m is an integer of 2-5, thus permitting the obtained photosensitive body to the high in sensitivity and superior in repetion characteristics in cases of positive and negative chargings.

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. Dispersed, Po I
JN- Organic photoconductive substances such as vinyl carbazole or polyvinyl anthracene, organic photoconductive substances such as phthalocyanine compounds or bisazo compounds dispersed in a resin binder or vacuum-deposited are used. There is.

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. 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, Po'J-N-vinylcarbazole and 2.4.7-)! A photoreceptor comprising J nitrofluoren-9-one (described in U.S. Pat. No. 3,484,237), a photoreceptor comprising an organic pigment as a main component, JP-A-47-37
543), 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]

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 (I) or (II).

[In formulas (I) and (II), R1, R2, R3 and R6 are each a hydrogen atom, a halogen atom, an alkyl group,
Alkoxy group, hydroxy group, allyl group, nitro group.

Represents an optionally substituted aryl group or amino group, R
4, Rs represents an optionally substituted aryl group. Moreover, n represents 1 or 22m represents an integer of 2 to 5 degrees. ] [Function] There is no known example in which a hydrazone compound represented by the above general formula (I) or (If) is used in a photosensitive layer.

In order to achieve the above objective, 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 (I) or (II) as a charge transport material is extremely effective in improving electrophotographic properties, and the use of a specific hydrazone compound represented by the above general formula (I) or (II) as a charge transport material has been found to be extremely effective in improving electrophotographic properties. As a result, we were able to obtain a photoreceptor with a unique structure.

〔Example〕

The hydrazone compound of the general formula (1) or (n) 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) or (n) thus obtained are as follows.

Compound No. I No. 2 No. 3 No. 4 No. 5 Compound No. 6 No. 7 No. 8 No. 9 Compound No. 11 No. 12 No. 13 No. 14 Compound No. 16 No. 18 Compound No. 21 No22 No, 23 No, 24 Compound No, 26 No, 27 No, 28 No, 29 No, 34 No, 37 No, 38 The photoreceptor of the present invention contains the above-mentioned hydrazone compound in the photosensitive layer. However, depending on how these hydrazone compounds are applied, Figure 1.

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

Figures 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 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 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 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. Examples of the charge generating substance include phthalocyanine compounds such as metal-free phthalocyanine and chichnylphthalocyanine, 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 the above-mentioned (I) or (I[) as an organic charge transport substance is dispersed in a resin binder, and in the dark, it acts as an insulating layer and absorbs the charge of the photoreceptor. It also functions to transport charges injected from the charge generation layer during light reception. As a resin binder, polycarbonate, polyester,
polyamide.

Polyurethane, epoxy, 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 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 5in2, metals, metal oxides, etc. can also be formed by vapor deposition, sputtering, etc.). As mentioned above, it is desirable that the material be as transparent as possible in the wavelength region where the light absorption of the charge generating material 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.

Examples of the present invention will be described below.

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

Example 2 First, α-type metal-free phthalocyanine is used as a starting material, and while two linear motors are placed facing each other, α-type metal-free phthalocyanine and a non-magnetic separation body containing a Teflon piece as a working piece are placed and pulverized. Electromagnetic pulverizer (product name L)
IMMAC (manufactured by Fuji Electric) was subjected to Fuji Electric frame treatment for 20 minutes to be pulverized. 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. After that, the sample and DM
F was separated by filtration and dried to obtain 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 thus obtained charge transport layer, 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 PMMA were mixed together with THF solvent for 3 hours. A coating solution was prepared by kneading it with a machine, and it was applied using a wire bar method to form a charge generation layer with a thickness of 1 μm after drying. Created.

Example 3 The composition of the photosensitive layer of Example 1 was changed to 50% metal-free phthalocyanine.
Parts by weight, hydrazone compound 1 represented by compound N023
00 parts by weight, polyester resin (trade name Byron 200
: manufactured by Toyobo Co., Ltd.) and 50 parts by weight of PMMA5Q, a photosensitive layer was formed in the same manner as in Example 1, and a photoreceptor was produced.

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 Vs (volts) of the photoreceptor is +6. Ok
This is the initial surface potential when corona discharge of V is performed for 10 seconds to positively charge the surface of the photoreceptor, and then the surface potential is V when held in the dark for 2 seconds with corona discharge stopped.
, (volts), and then irradiate the surface of the photoreceptor with white light with an illuminance of 2 lux to find the time (seconds) it takes for Vd to be halved, and calculate the half-attenuation exposure amount E1/2 (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 Vr (volt). In addition, when a phthalocyanine compound is used as a charge generating substance, high sensitivity with long wavelength light can be expected.
At the same time, the gauntlet photographic characteristics were measured using 0 nm monochromatic light. That is, measure up to Vd in the same way, then irradiate 1 μW monochromatic light (780 nm) instead of white light to find the half-attenuation exposure amount (μJ/cn), and
The residual potential Vr (volts) when the surface of the photoreceptor was irradiated for 0 seconds 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 an aluminum plate marked with a thickness of 500μ.
．． 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. Then, a photoreceptor having the configuration shown in FIG. 2 was manufactured.

When this photoreceptor was corona charged at -5,QkV for 0.2 seconds, the result was Vs--610V.

Good results were obtained with Vr=-60V and E1/2=5.2 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 No. 5, a polycarbonate resin (
Panlite L-1250'') 100 parts by weight, 0.1 part by weight of silicone oil, 700 parts by weight of THF and 70 parts by weight of toluene.
They were mixed at 0 parts by weight and coated on the charge generation layer to a thickness of about 15 μm to form a charge transport layer.

The photoreceptor thus obtained was subjected to -6:0 kV corona charging for 0.2 seconds in the same manner as in Example 5, Vs = 630V, E l/2 = 6.4.
A good result of lux·sec was obtained.

Example 7 Photosensitive layers were prepared in the same manner as in Example 4 for each of Compounds No. 6 to No. 40, and the results were measured using rSP-428J, and the results are shown in Table 2. This result is + in the dark.
5. It is expressed as half-attenuation exposure amount E1/2 (lux seconds) when corona discharge of QkV is performed for 10 seconds to positively charge and white light with an illuminance of 2 lux is irradiated.

Table 2 As seen in Table 2, the hydrazone compound No.
The half-attenuation exposure amount E +, 2 was also good for the photoconductors using No. 6 to No. 40 as the charge transport material.

〔Effect of the invention〕

According to the present invention, since the hydrazone compound represented by (I) or (II) above is used as a charge transport substance on a conductive substrate, it is highly sensitive even in positive and negative charging, and has excellent repeatability. An excellent photoreceptor 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 DESCRIPTION OF THE DRAWINGS 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 hydrazone compound represented by the following general formula (I) or (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・( I
) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(II) [In formulas (I) and (II), R_1, R_2, R_3 and R_4 are hydrogen atoms, halogen atoms, alkyl groups, and alkoxy, respectively. group, hydroxy group, allyl group, nitro group. Represents an optionally substituted aryl group or amino group, R
_4 and R_5 represent an optionally substituted aryl group. Further, n represents 1 or 2, and m represents an integer of 2 to 5. ]