JPS63167370A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain high sensitivity and superior characteristics against repeated uses by incorporating a specified hydrazone compound as an essential component in an electric charge transfer material. CONSTITUTION:The hydrazone compound represented by formula I is incorporated in a photosensitive layer 2 as a charge transfer material 5 in which R1 is H, alkyl, halogen, or the like, and each of R2 and R3 is optionally substituted alkyl, aralkyl, or aryl or the like. This hydrazone compound can be synthesized by the ordinary method, that is by condensing aldehydes and hydrazines in a proper organic solvent, such as alcohols, as necessary, in the presence of a small amount of acid, as a condensing agent, thus permitting the obtained photosensitive body to be high in sensitivity even in the case of positive charging and negative charging, and superior in characteristics against repeated uses.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor comprising a photosensitive layer formed on a conductive substrate, and particularly relates to a novel hydrazone as a charge transport substance in the photosensitive layer. The present invention relates to an electrophotographic photoreceptor that contains a compound and has high sensitivity and excellent repeatability, and is mainly used in copying machines or printers.

[Conventional technology]

2. Description of the Related Art Electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) used in copiers or printers are constructed by forming a photosensitive layer on a conductive substrate. Such photoreceptors generally require a function to retain surface charge in the dark, a function to receive light and generate a charge, a function to similarly receive light and transport charge, etc. There are so-called single-layer type photoreceptors that have both of these functions, and so-called laminated type photoreceptors that are functionally separated into a layer that mainly contributes to charge generation and a layer that contributes to surface charge in the dark and 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 of a document on the surface of the charged photoconductor, and discharging the formed electrostatic latent image. This phenomenon is caused by toner, and the resulting toner image is fixed 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.

Conventionally, the photosensitive layer of the photoreceptor mentioned above has been made of inorganic photoconductive substances such as selenium or selenium alloys, zinc oxide, and cadmium sulfide, or organic photoconductive substances such as poly-N-vinyl carbazole, polyvinyl anthracene, phthalocyanine compounds, and bisazo compounds. There are known materials in which a chemical substance is dispersed in a resin binder or vacuum-deposited.

In recent years, electrophotographic photoreceptors using organic photoconductive materials have been put into practical use due to their advantages such as flexibility, thermal stability, and film-forming properties. For example, a photoreceptor using poly-N-vinyl carbazole and 2,4,7-1-linitrofluoren-9-one (see U.S. Pat. No. 3,484,237), containing an organic pigment as a main component. (see JP-A-47-37543), a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (JP-A-47-107)
(See Publication No. 53).

[Problem that the invention seeks to solve]

However, although the above-mentioned organic photoconductive materials have many advantages that inorganic photoconductive materials do not have, at the same time, they have not yet been able to fully satisfy all the characteristics required for electrophotographic photoreceptors. At present, a photoreceptor with high sensitivity and excellent repeatability is strongly desired.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor which has high sensitivity and excellent repeatability by incorporating a novel hydrazone compound in the photosensitive layer, and which improves the drawbacks of the above-mentioned known techniques.

[Means for solving problems]

In order to achieve the above object, the present invention provides an electrophotographic photoreceptor comprising a photosensitive layer formed on a conductive substrate, wherein the photosensitive layer contains a charge transporting substance represented by the following general formula. It is characterized by containing a hydrazone compound as an essential component.

General formula: In the formula, R1 is hydrogen, halogen, alkyl group, alkoxy group, nitro group, amino group, R2 and R3 are each substituted or unsubstituted alkyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted Represents a group.

The hydrazone compound of the above general formula used in the present invention is synthesized by a conventional method. That is, it is synthesized by condensing aldehydes and hydrazines in a suitable organic solvent such as alcohol, if necessary in the presence of a small amount of acid as a condensing agent. Specific examples of such hydrazone compounds are as follows.

Fan, % CxHy bend λ? Further, the above-mentioned conductive substrate according to the present invention serves as an electrode for the photoreceptor and at the same time serves as a support for each of the other layers described below, and may be cylindrical, plate-shaped, or film-shaped, and the material may be In particular, it may be made of metal such as aluminum, stainless steel, or nickel, or it may be made of glass resin or the like subjected to conductive treatment.

The photoreceptor of the present invention is one in which a photosensitive layer is formed on the above-mentioned conductive substrate, and the above-mentioned hydrazone compound is contained in this photosensitive layer. There are three forms.

FIG. 1 shows a structure in which a photosensitive layer 2 is formed on a conductive substrate 1, which is usually referred to as a single-layer photosensitive member. It is formed by dispersing a hydrazone compound in a resin binder. This type of photoreceptor is formed by dispersing a charge generating material 3 in a solution containing a charge transporting material 5 and a resin binder, and applying this dispersion onto a conductive substrate 1.

FIG. 2 shows a photosensitive layer 2' consisting of a laminate of 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. The charge generating material 3 is vacuum-deposited on the conductive substrate 1, or particles of the charge generating material 3 are dispersed in a solvent or a resin binder. It is formed by applying and drying a dispersion liquid, and then applying a solution in which the charge transport material 5 and a resin binder are dissolved thereon and drying it.

FIG. 3 shows the reverse layer formation of FIG. 2, in which a solution containing a charge transporting material 5 and a resin binder is applied onto a conductive substrate 1 and dried, and a charge generating material 3 is vacuum-evaporated thereon. Alternatively, a dispersion obtained by dispersing particles of the charge generating substance 3 in a solvent or a resin binder is coated and dried, and a coating layer 7 is further formed thereon.

In FIGS. 2 and 3, the charge generation N4 has a function of receiving light and generating charges, and has a high charge generation rate, and at the same time, the charge transport layer 6 and the coating in FIG. It is necessary to have good injection properties into the layer 7, and it is desirable that there is little dependence on electric field and that injection is good even in a low electric field.

The charge generating substance 3 is metal-free phthalocyanine,
Phthalocyanine compounds such as titanyl phthalocyanine,
Various azo, quinone, indigo pigments, selenium or selenium compounds are used, and a suitable substance can be selected depending on the light wavelength range of the exposure light source used for image formation. Since the charge generation layer 4 only needs to have a charge generation function, its thickness is determined by the light absorption coefficient of the charge generation substance 3.
Generally it is 5μ or less, preferably 1μ or less.

This charge generation layer 4 may be mainly composed of the charge generation substance 3 and may be used by adding a charge transport substance or the like thereto. As the resin binder for this layer, polycarbonate, polyester, polyamide, polyurethane, epoxy resin, silicone resin, methacrylic acid ester polymer or copolymer, etc. are used, or an appropriate combination of these is used.

The charge transport layer 6 is a coating film in which the above-mentioned hydrazone compound 5 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 of the photoreceptor, and when receiving light, it acts as the charge generating layer 4. It functions to transport charges injected from the The resin binder of this layer is the same as that of the charge generation layer 4 described above.

The coating layer 7 has the function of receiving and retaining the charges of corona discharge in a dark place, and has the ability to transmit the light to which the charge generation layer N4 is sensitive. It is necessary to neutralize and eliminate the surface charges by injecting the generated charges. This covering material is polyester.

Organic insulating film forming materials such as polyamide can be applied. Also these organic materials and glass resins.

It is also possible to use a mixture of inorganic materials such as Stow, and materials that reduce electrical resistance such as metals and metal oxides. Note that this coating material is not limited to organic insulating film forming materials, but may include inorganic materials such as 5iO7,
Furthermore, metals, metal oxides, etc. can also be used 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 3 absorbs maximum light. Covering layer 7
Although the film thickness depends on the composition, 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.

〔Example〕

50 parts by weight of metal-free phthalocyanine (manufactured by Tokyo Kasei Co., Ltd.) milled for 150 hours in a Taish soil ball mill and 100 parts by weight of a hydrazone compound represented by Compound 1 above were mixed into a polyester resin (Vylon; manufactured by Toyobo Co., Ltd.). ) and a tetrahydrofuran (THF) solvent for 3 hours in a mixer to prepare a coating solution.The coating solution was applied to an aluminum-deposited polyester film (A 1-
A photoreceptor was manufactured by applying the photoreceptor onto PET) by a wire bar method so that the film thickness after drying was 15 μm.

First, α-type metal-free phthalocyanine is used as a starting material, and this starting material is transferred between two linear motors arranged opposite to each other. Place the magnetic case and LIMMAC (
Linear Induction Motor Mi
-Xingand Crashing (manufactured by Fuji Electric Co., Ltd.) for 20 minutes to form a fine powder. Next, 1 part by weight of this finely powdered sample was added to DMF (N, N
Ultrasonic dispersion treatment was performed together with 50 parts by weight of a solvent (dimethylformamide). Thereafter, the sample and DMF were separated, filtered, and dried to obtain a treated metal-free phthalocyanine.

Furthermore, a hydrazone compound 1 represented by the compound magnetic 1
00 parts by weight was dissolved in 700 parts by weight of tetrahydrofuran (THF), and this solution was mixed with a solution prepared by dissolving 100 parts by weight of polymethyl methacrylate polymer (pMMA: manufactured by Songkyo Kasei Co., Ltd.) in 700 parts by weight of toluene. The resulting coating solution was applied onto an aluminum-deposited polyester film substrate using a wire bar so that the film thickness after drying was 15 μm, and after drying, a charge transport layer was formed.

Next, 50 parts by weight of the metal-free phthalocyanine 2 Polyester resin (trade name Vylon 200; manufactured by Toyobo Co., Ltd.) 5
0 parts by weight and 50 parts by weight of PMMA were kneaded with a THF solvent in a mixer for 3 hours to prepare a coating solution, and this coating solution was coated on the charge transport layer with a wire so that the film thickness after drying was 1μ. After coating with a bar and drying, a charge generation layer was obtained.

The coating solution of Example 1 was superimposed on 50 parts of hot metal phthalocyanine, and the compound! Same as Example 1 except that the coating liquid was changed to have a composition of 100 parts by weight of a hydrazone compound represented by 1h1, 50 parts by weight of a polyester resin (trade name Vipin 200; manufactured by Toyobo Co., Ltd.), and 50 parts by weight of PMMA. A photoreceptor was manufactured.

Large seed plate ↓ Example 3 except that the metal-free phthalocyanine in Example 3 was changed to chlorodia ampule, which is a bisazo dye.
A photoreceptor was manufactured in the same manner as above.

The electrophotographic characteristics of the photoreceptors according to each example obtained as described above were measured using an electrostatic recording paper tester rSP-4 manufactured by Kawaguchi Electric.
28".

The surface potential Vs (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 then the surface potential Vd (volt) is measured when the photoreceptor surface is held in the dark for 2 seconds with corona discharge stopped. Furthermore, the time it takes for Vd to be halved by irradiating white light with an illuminance of 2 lux onto the surface of the photoreceptor (
The half-attenuation exposure amount El/2 (lux/second) was determined. 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,
Since high sensitivity can be expected with long wavelength light, the wavelength of 780n
Electrophotography and characteristics using m monochromatic light were also measured at the same time. That is, measurements are made in the same way up to Vd, then 1 μW monochromatic light (780 nm) is irradiated instead of white light to obtain the half-attenuation exposure it (μJ/cal), and this light is applied to the photoreceptor surface for 10 seconds. The residual potential Vr (volts) when irradiated was measured. The measurement results are shown in Table 1.

Table 1 White light 7BOr+m wavelength light V
s Vr E+zz Vs
Vr E, 7゜volt volt lux second volt volt μJ/crA Example 1475
25 3.1 460 40 1.1 Example 2680 50 3.5 660
35 1.0 Example 3620 65 3.8
600 30 0.8 Example 4640 6
0 3.5 - --As seen in Table 1; Examples 1, 2, and 3゜4 were all comparable in half-attenuation exposure and residual potential, and also showed good characteristics in terms of residual potential. There is.

1. Selenium is applied to a thickness of 1.5 mm on an aluminum plate with a thickness of 500 μm.
A charge generation layer was formed by vacuum evaporation on a 5μ film, and then a solution obtained by dissolving 100 parts by weight of the hydrazone compound shown in Compound No. 15 in 700 parts by weight of tetrahydrofuran (THF) and polymethyl methacrylate polymer (PMMA: Tokyo Kasei) were added. Co., Ltd.) dissolved in 700 parts by weight of toluene to prepare a coating solution, and apply this coating solution to the charge generation layer using a wire bar so that the film thickness after drying becomes 20 μm. After coating and drying, a charge transport layer was formed. When this photoreceptor was corona charged at -6, ORV for 0.2 seconds, VS = -830V, V r =
50. El/2 = 4.5 lux·sec, which was a good result.

50 parts by weight of the metal-free fluorocyanine of Example 1 of Otoshi Coal Works, 50 parts by weight of polyester resin (trade name Byron 200: Toyobo Co., Ltd.'!), and 50 parts by weight of PMMA were kneaded with a THF solvent in a mixer for 3 hours. A coating solution was prepared by tIjl,
This 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 Magnetic 20, 100 parts by weight of polycarbonate resin (Panlite L-1250), and 0.1 parts by weight of silicone oil were mixed with 700 parts by weight of THF and 700 parts by weight of toluene to generate a charge. A charge transport layer was formed by coating the layer to a thickness of approximately 1.5 μm.

The thus obtained photoreceptor was corona charged with -6, OKVK for 0.2 seconds in the same manner as in Example 4, resulting in Vs = -740, V, El/2 = 2.5)
Lt socks seconds, and good results were obtained.

Large construction Example 2 The aluminum thinly bonded polyester film (A/-PUT) as the conductive substrate was used with an outer diameter of 60 mm.
The drum was replaced with an At drum having a length of 320 mm, and a charge transport layer (15 μm) and a charge generation layer (2 μm) were coated on the outer peripheral surface of this drum by dip coating to form a photoreceptor.

This photoreceptor was installed in a Carlson type copying machine, and 100
The illustrations were evaluated on consecutive sheets. Good image quality was achieved with no deterioration in image quality or background smearing. Furthermore, the photoreceptor of Example 7 was installed in the same copying machine, the image area was removed, and a surface electrometer was installed to measure potential changes during the copying process.

The results are shown in Table 2.

Table 2 Potential of dark area Potential of bright area (volts) (volts) 1st 100th 1st 100th Example 7
640 620 100 110 As is clear from Table 2, the above photoreceptor exhibited good repeatability.

〔Effect of the invention〕

According to the above-described present invention, since the hydrazone compound represented by the above-mentioned general formula is used as a charge transport substance on a conductive substrate, a photoreceptor with high sensitivity and excellent repeatability even in positive and negative charging 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 form a coating layer on the surface to improve durability.

[Brief explanation of the drawing]

1 to 3 are conceptual cross-sectional views showing embodiments of the photoreceptor of the present invention.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising a photoreceptor layer formed on a conductive substrate, wherein the photoreceptor layer contains a hydrazone compound represented by the following general formula as a charge transport substance as an essential component. An electrophotographic photoreceptor comprising: General formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, R_1 is hydrogen, halogen, alkyl group, alkoxy group, nitro group, amino group, R_2 and R_3 are substituted or unsubstituted alkyl groups, substituted or unsubstituted, respectively. Represents a substituted aralkyl group or a substituted or unsubstituted aryl group.