JPH03109554A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and repeated uses enduring characteristics by forming a photosensitive layer containing a specified compound. CONSTITUTION:The photosensitive layer 20 to be formed on a conductive substrate 1 contains an electric charge generating material 3 and as a charge transfer material 5 at least one of the compounds represented by formula I and II, and in formula I each of R1 and R2 is H, halogen, alkyl, or aryl, and A is an aryl or heterocyclic group each optionally substituted, and in formula II, R1 is H, halogen, or alkyl; each of R2 and R3 is H, an alkyl, aryl, or heterocyclic group; and A is an aryl or heterocyclic group each optionally substituted, thus permitting sensitivity and repeated enduring characteristics even in the case of both of positive and negative charging to be enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor characterized by containing a novel compound in a photosensitive layer formed on a conductive substrate. Related to photographic photoreceptors.

[Conventional technology]

Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) have been made of inorganic photoconductive substances such as selenium or selenium alloys, or inorganic photoconductive substances such as zinc oxide or cadmium sulfide in a resin binder. organic photoconductive substances such as poly-N-vinylcarbazole or polyvinylanthracene, organic photoconductive substances such as phthalocyanine compounds or bisazo compounds dispersed in a resin binder or vacuum-deposited. and other items are being 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 the latent image with toner, transferring the developed toner image to a support such as paper, and fixing it. After the toner image is transferred, the photoreceptor is charged, the residual toner is removed,
After photostatic charge removal, etc., it is reused.

In recent years, many applications of photoconductive organic compounds with excellent charge transport ability to photoreceptors have been proposed due to their advantages such as flexibility, thermal stability, and film-forming properties. For example, as oxadiazole compounds, US Pat. No. 3,189,447;
For pyrazoline compounds, see Japanese Patent Publication No. 59-2023, and for hydrazone compounds, see Japanese Patent Publication No. 55-423.
Various charge transport materials are known from Japanese Patent Application Laid-open No. 80, JP-A-57-101844, JP-A-54-150128, and as a stilbene compound, JP-A-58-198043.

[Problem to be solved by the invention]

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. There were problems with photosensitivity and characteristics during repeated and continuous use.

This invention was 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, we provide electrophotographic photoreceptors for copiers and printers that have excellent responsiveness, high sensitivity, and excellent repeatability. The task is to do so.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, there is provided a photosensitive layer for electrophotography comprising at least one compound represented by the following general formula (I) or (II). Use as a photoreceptor.

[In formula (I), R5 and R2 are each a hydrogen atom.

It represents any one of a halogen atom, an alkyl group, and an aryl group, and A represents either a substituted or unsubstituted aryl group or a heterocyclic group. [1] [In formula (n), R1 represents any one of a hydrogen atom, a halogen atom, and an alkyl group, and R2 and R3 are a hydrogen atom, an alkyl group, and an aryl group, respectively.

It represents any of the heterocyclic groups, and A represents either a substituted or unsubstituted aryl group or a heterocyclic group.

] The compound represented by the general formula (I) or (II) is
For example, aldehydes represented by the following general formula (III) or (rV) and, for example, the following general formula (V) or (Vl
) and a known Wittig reagent.
It can be synthesized by a reaction.

A -(HO-(nl) [A in formulas (III) and (rV) represents either a substituted or unsubstituted aryl group or a heterocyclic group,
RI and R2 in formula (V) each represent a hydrogen atom, a halogen atom, a halogen atom, an alkyl group, or an aryl group, and R2 and R3 in formula (Vl) each represent a hydrogen atom, an alkyl group, or an aryl group. group or a heterocyclic group, and R1 represents a lower alkyl group. ] Specific examples of the compound represented by the general formula (I) or (II) are as follows.

(2H5 L, M1 C2H5 [Function] There is no known example of using a compound represented by the above general formula (I) or (II) in a photosensitive layer.The present inventors have developed various methods to solve the above problems. As a result of conducting a number of experiments on these compounds while intensively studying organic materials, we found that although the technical elucidation of these compounds has not yet been fully elucidated, the compounds represented by the above-mentioned general formula (I) or (II) The use of certain compounds as charge transport materials
discovered that it is extremely effective in improving electrophotographic properties,
This led to the creation of a photoreceptor with high sensitivity and excellent repeatability.

〔Example〕

The photoreceptor of this invention contains the above-mentioned compounds in the photosensitive layer, but depending on the application of these compounds, it can be used as shown in FIG. 1, FIG. 2, or FIG. 3. I can do it.

1 to 3 are conceptual cross-sectional views of the photoreceptor of the present invention,
1 is a conductive substrate, 20, 21, 22 is a photosensitive layer, 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 charge-transporting substance 5 are dispersed in a resin binder (binder) is provided on a conductive substrate 1. It is something that

FIG. 2 shows a photosensitive layer 21 (usually a laminated type photoreceptor) consisting of a charge generation layer 4 mainly containing a charge generation substance 3 and a charge transport layer 6 containing a charge transport substance 5 on a conductive substrate 1. It is equipped with a configuration called .

In FIG. 3, a photosensitive layer 22 having a layer structure opposite to that in FIG. 2 is provided. 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 the current stage, it is necessary to have the layer structure shown in FIG. 3 as a positive charging type photoreceptor.

The photoreceptor shown in FIG. 1 can be produced by dispersing or dissolving a charge generating substance in a solution containing a charge transporting substance and a resin binder, and coating this coating liquid on a conductive substrate.

The photoreceptor shown in FIG. 2 is produced by vacuum-depositing a charge-generating substance on a conductive substrate, or by applying a coating solution obtained by dispersing or dissolving particles of a charge-generating substance in a solvent or a resin binder, and drying it. It can be produced by applying a solution containing a charge transport substance and a resin binder thereon 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 coating liquid obtained by dispersing or dissolving 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 or dissolved in a solvent or a resin binder as described above, or by a method such as vacuum deposition, and is formed by receiving light. Generates electric charge. 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. As charge generating substances, phthalocyanine compounds such as metal-free phthalocyanine and titanyl phthalocyanine, various azo,
Pigments such as quinone and indigo, or cyanine, squaryllium, and azulenium.

Dyes such as biryllium compounds, selenium or selenium compounds 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 5μ.
m 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. Resin binders include polycarbonate, polyester, polyamide, polyurethane, vinyl chloride, and epoxy.

Diaryl phthalate resins, silicone resins, polymers and copolymers of methacrylic acid esters, etc. can be used in appropriate combinations.

The charge transport layer 6 is a coating film in which a compound represented by the general formula (I) or (II) as an organic charge transport substance is dispersed in a resin binder, and serves as an insulating layer to retain the charge of the photoreceptor in a dark place. However, when receiving light, 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 inorganic polymer resins.

It is also possible to use a mixture of inorganic materials such as 5i02 and materials that reduce electrical resistance such as metals and metal oxides. The coating material is not limited to organic insulating film-forming materials (inorganic materials such as 5i02, as well as metals, metal oxides, etc., can be vapor-deposited).

It is also possible to form by a method such as 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 50 parts by weight of X-type metal-free phthalocyanine (82PC) and 100 parts by weight of the compound represented by the compound Nα1 were mixed into a polyester resin (trade name: Vylon 200, manufactured by Toyobo) 1
00 parts by weight and a tetrahydrofuran (THF) solvent for 3 hours in a mixer to prepare a coating solution, and coated with aluminum vapor-deposited polyester film (AJ-P) as a conductive substrate.
ET) by a wire bar method to form a photosensitive layer having a dry film thickness of 15 μm, thereby producing a photoreceptor having the structure shown in FIG. 1.

Example 2 A coating solution prepared by dissolving 80 parts by weight of the compound represented by the compound Nα2 and 100 parts by weight of polycarbonate resin (trade name Panlite L-1225, manufactured by Ondai) in methylene chloride was applied to an aluminum-deposited polyester film substrate. A charge transport layer was formed by coating on top by a wire bar method so that the film thickness after drying was 15 μm. On the charge transport layer thus obtained, 50 parts by weight of titanyl phthalocyanine (TiOPc), which had been pulverized by a ball mill for 150 hours, and 50 parts by weight of a polyester resin (trade name: Vylon 200, manufactured by Toyobo) were mixed with a THF solvent for 3 hours. A coating solution was prepared by kneading it with a mixer, and it was applied using a wire bar method to form a charge generation layer so that the film thickness after drying was 1 μm, and a photoreceptor corresponding to the structure shown in FIG. 3 was prepared. was created.

However, a coating layer not directly related to this invention was not provided.

Example 3 In fact, a photoreceptor was produced in the same manner as in Example 2, except that Ti0Pc in Example 2 was changed to a squarylium compound represented by the following structural formula, and the charge transport material was changed to a compound represented by the compound N13. did.

Example 4 Ti0Pc in Example 2 was prepared using, for example, JP-A-47-37.
The procedure of Example 2 was changed to Chlorodiane Blue, a bisazo pigment as shown in Japanese Patent No. 543, and the charge transport substance was changed to the compound represented by the compound Nα4.
A photoreceptor was produced in the same manner as described above.

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 is Vd (
Next, the photoreceptor surface was irradiated with white light with an illuminance of 2 lux, and the time (seconds) until Vd was halved was determined, and the half-attenuation exposure amount El, □ (lux seconds) 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 V (volt). Further, for Examples 1 to 3, since high sensitivity with long wavelength light can be expected, the electrophotographic characteristics when using monochromatic light with a wavelength of 780 nm were also measured at the same time. That is, measurements were made in the same way up to Vd, and then 1 μW monochromatic light (
The half-attenuation exposure amount (μJ/am) was determined by irradiating the photoreceptor with 780 weight m), and the residual potential V, (volt) when the surface of the photoreceptor was irradiated with this light for 10 seconds was measured.

The measurement results are shown in Table 1.

Table 1 As seen in Table 1, Examples 1, 2.3 and 4 are comparable in half-attenuation exposure and residual potential, and also exhibit good characteristics in terms of surface potential. In addition, Example 1
~Wavelength in 3? It can be seen that it shows high sensitivity even with long wavelength light of 3Qnm, and can be used satisfactorily 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 compound represented by compound Nα5 (100×1111) and polycarbonate resin (PC2200: manufactured by Mitsubishi Gas Chemical Co., Ltd.) 100
A coating liquid prepared by dissolving parts of The body was created. For this photoreceptor, the corona discharge voltage is −
The electrophotographic characteristics were measured in the same manner as in Examples 1 to 4 above, except that the voltage was 6.0 kV.
-680V, V, = -50V.

A good result was obtained, E,/2=1.9 lux·sec.

Example 6 50 parts by weight of X-type metal-free phthalocyanine and 51 parts by weight of vinyl chloride copolymer (trade name MR-41f, manufactured by Nippon Zeon) were kneaded together with methylene chloride in a mixer for 3 hours to prepare a coating liquid. prepared and deposited approximately 1 μm on an aluminum support.
A charge generation layer was formed. Next, 100 parts by weight of a compound represented by compound Nα6 and a polycarbonate resin (trade name Panlite L-1250: Music University M)
100 parts by weight of silicone oil and 0.1 parts by weight of silicone oil were mixed with methylene chloride, and the mixture was coated on the charge generation layer to a thickness of about 15 μm to form a charge transport layer, thereby producing a photoreceptor.

The electrophotographic properties of the thus obtained photoreceptor were measured in the same manner as in Example 5.V.

=-650V, E l/2 =2.3 ru/x.
seconds (!: Good results were obtained.

Example 7 A photoreceptor was produced in the same manner as in Example 6, except that the metal-free phthalocyanine in Example 6 was changed to a bisazo pigment represented by the following structural formula, and the charge transport substance was changed to a compound represented by compound Nα7. .

When the electrophotographic characteristics of the thus obtained photoreceptor were measured in the same manner as in Example 5, V-=-650V,
A good result of E l/2-2.1 lux·sec was obtained.

Example 8 Photoreceptors were prepared in the same manner as in Example 4 for each of the compounds Nα8 to N[L42, and the electrophotographic properties were measured in the same manner as in Examples 1 to 4.

Among them, the measurement results of the half-attenuation exposure amount El/l (lux/second) are shown in Table 2.

Table 2 (Part 2) As seen in Table 2, the compounds Nα8 to Nα42
The half-attenuation exposure amount El/□ of the photoreceptor using as a charge transport material was also good in all cases.

〔Effect of the invention〕

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

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are conceptual cross-sectional views showing different embodiments of the photoreceptor of the present invention. 1. Conductive substrate, 3. Charge generating substance, 4. Charge generating 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 photosensitive layer comprising a photosensitive layer containing at least one compound represented by the following general formula (I) or (II): body. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・( I
) [In formula (I), R_1 and R_2 each represent a hydrogen atom, a halogen atom, an alkyl group, or an aryl group, and A is a substituted or unsubstituted aryl group,
Represents any heterocyclic group. 〕▲Mathematical formula, chemical formula,
There are tables, etc.▼・・・・・・(II) [In formula (II), R_1 represents a hydrogen atom, a halogen atom, or an alkyl group, and R_2 and R_3 represent a hydrogen atom, an alkyl group, or an alkyl group, respectively. It represents either an aryl group or a heterocyclic group, and A represents either a substituted or unsubstituted aryl group or a heterocyclic group. ]