JPH03287170A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body high in sensitivity and superior in red reproduction performance by using a specified bisazo compound as an electric charge generating material and a specified hydrazone compound as a charge transfer material. CONSTITUTION:The photosensitive layer 4a comprises the lower charge generat ing layer 2 containing at least one of the bisazo compounds represented by formula I as the charge generating material and the upper charge transfer layer 3 containing at least one of the hydrazone compounds represented by formula II as the charge transfer material, and in formulae I and II, Z is a heterocyclic group; R1 is alkyl; R2 is H, cyano, carbamoyl, or the like; A is aryl or a heterocyclic group; R3 is alkyl or aryl; R4 is H, haloen, alkyl, or the like; and (n) is 0 or 1, thus permitting the obtained photosensitive body to be high in sensitivity and superior in red color reproduction performance in the case of positive charging and negatively charging.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, it is equipped with a charge generation layer and a charge transport layer containing an organic material, and is suitable for use in electrophotographic copying machines, etc. The present invention relates to a laminated electrophotographic photoreceptor that is used.

[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
Organic photoconductive substances such as J-N-vinylcarbazole, polyvinylanthracene, and phthalocyanine compounds, and organic leading conductive substances such as phthalocyanine compounds or bisazo compounds dispersed in resin binders are used.

The photoreceptor also needs to 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, but these functions can be achieved in three layers. A so-called single-layer type photoreceptor with a combination of two types of photoreceptors, and a so-called laminated photoreceptor with functionally separated layers: a layer that mainly 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. There is a type 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, transferring the developed toner image to a support such as paper, and fixing it. After the toner image has been transferred, the photoreceptor is subjected to static neutralization, removal of residual toner, photostatic static elimination, etc. Subject to reuse.

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. A typical example is a photoreceptor using a phthalocyanine compound as a charge generating substance (US Pat. No. 38161).
18), photoreceptors using azo compounds (JP-A-57-176D55, JP-A-60-4566)
4), a photoreceptor using a perylene compound (described in JP-A-63-271461), a photoreceptor using a polycyclic bovine compound (described in JP-A-6059588), etc. ing.

[Problem to be solved by the invention]

By the way, when applying these organic photoreceptors to copying machines, one of the important conditions that must be satisfied in terms of sensitivity, printing durability, and environmental resistance is the reproducibility of red images. .

For example, some phthalocyanine compounds and azo compounds have high photosensitivity to light reflected from red images, so
Red image reproducibility cannot be obtained.

In order to overcome this drawback, a method of adding a dye to the charge transport layer may be considered, but this method deteriorates the charge transport ability of the charge transport layer itself. Further, it cannot be used in a layer structure in which the charge generation layer is placed above the charge transport layer. Therefore, the development of azo compounds, perylene compounds, and polycyclic quinone compounds that are insensitive to the reflected light of red images is underway, but photoreceptors using these materials are suitable for electrophotography required for copying machines. There is no material that fully satisfies these characteristics, and with the recent increase in the speed of copying machines, there is a strong desire for materials with high sensitivity and excellent red color reproducibility.

This invention provides a charge generation layer comprising an organic material.

To provide an electrophotographic photoreceptor for a copying machine, which has a charge transport layer and has excellent electrophotographic properties, with high sensitivity and good red reproducibility, by eliminating the above-mentioned drawbacks. is the issue to be solved.

[Means to solve the problem]

According to the present invention, the above problem can be solved by using the following general formula as a charge generation substance of the charge generation layer in an electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer comprising an organic material on a conductive substrate. The solution is to provide a photoreceptor containing at least one bisazo compound represented by (I) and using at least one hydrazone compound represented by the following general formula (II) as a charge transport material in the charge transport layer. be done.

Further, in the above photoreceptor, the charge generation layer contains at least one bisazo compound represented by the following general formula (I) as a charge generation substance, and the charge transport layer contains at least one bisazo compound represented by the following general formula (III) as a charge transport substance. This problem can be solved by using a photoreceptor using at least one of the stilbene compounds shown in the following.

z
'z [In formula (I), Z represents an optionally substituted heterocyclic residue, R1 represents an optionally substituted alkyl group, R2 is a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester represents either a group or an acyl group. [In formula (II), A represents any of the following optionally substituted aryl groups and heterocyclic groups, and R3 represents any of the following optionally substituted alkyl groups and aryl groups. Represents any of the following, R6 is a hydrogen atom, a halogen atom, each of the following optionally substituted alkyl groups,
Represents any aryl group, and n does not represent O or 1. [In formula (III), B represents any of the following optionally substituted aryl groups and heterocyclic groups, and R5 and R6 represent the following optionally substituted alkyl groups, aryl groups, and heterocyclic groups, respectively. It represents any of the ring groups, and m represents O or 1. ] Specific examples of the compounds represented by the above general formulas (I), (formerly and (III)) used in this invention are as follows.

Compound N9I-1 9I-7 0 Compound N91[-1 N911-2 911-3 NgII-4 911-5 Compound N911-11 N911-12 N911-13 Ht - Compound N911-6 911-7 N91[-8 911- 9 2H5 N911-10 Compound N911-16 N911-17 H3 NgII-18 N911-19 N911-20 ■ C2H5 Compound N911-21 N911-22 N911-23 [Function] As a charge generating substance, represented by the above general formula (I) Using a bisazo compound, the above general formula (■) is used as a charge transporting substance.
By using the hydrazone compound represented by the formula (I) or the stilbene compound represented by the general formula (I), it is possible to obtain a photoreceptor with high sensitivity and excellent red reproducibility.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are conceptual cross-sectional views showing different embodiments of the photoreceptor of the present invention, where ■ is a conductive substrate;
, 4b is a photosensitive layer, and 2 is a charge generation layer.

3 is a charge transport layer, 5 is a surface coating layer, and the photosensitive layer is of a functionally separated type in which a charge generation layer and a charge transport layer are separated. The photosensitive layer 4a in FIG. 1 is laminated in the order of charge generation layer 2 and charge transport layer 3, and in some cases, five surface coating layers may be provided. The photosensitive layer 4b in FIG. 2 is opposite to that in FIG. 1, and the charge transport layer 3. The charge generation layer 2 is laminated in this order.

8 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, or nickel metal. It may also be made of metal, glass, resin, or the like, which has been subjected to conductive treatment.

The charge-generating layer 2 is formed by vacuum-depositing a charge-generating substance or by applying a material in which particles of a charge-generating substance are dispersed in a resin binder, and generates charges by receiving light. . In addition to the high charge generation efficiency, the ability to inject the generated charges into the charge transport layer 4 is also important, and it is desirable that the charge is less dependent on the electric field and can be injected even in a low electric field.

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.
It is 1 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 4 is a coating film made of a material in which an organic charge transport substance is dispersed in a resin binder, and in the dark, it serves as an insulating layer to retain the charge on the photoreceptor, and when receiving light, it is injected from the charge generation layer. Demonstrates the function of transporting electric charge. As a resin binder, polycarbonate, polyester,
Polymers and copolymers of methacrylic acid esters are used, but compatibility with the charge transport substance is important in addition to mechanical, chemical, and electrical stability, adhesion, and the like.

In order to maintain a practically effective surface potential, the thickness of the charge transport layer is preferably in the range of 3 μm to 30 μm, more preferably 5 μm to 20 μm.

The surface coating layer 5 has excellent durability against mechanical stress,
Furthermore, it is composed of a chemically stable substance, has the function of accepting and retaining the charge of corona discharge in the dark, and has the ability to transmit the light to which the charge generation layer is sensitive, so that it is not exposed to light when exposed to light. It is necessary for the light to pass through, reach the charge generation layer, and receive the injection of the generated charges to neutralize and eliminate the surface charges. Furthermore, as described 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.

As coating materials for the surface coating layer, acrylic modified silicone resins, epoxy modified silicone resins, alkyd modified silicone resins, polyester modified silicone resins, urethane modified silicone resins, etc. are used as modified silicone resins, and silicone resins as hard coating agents are used. can. These modified silicone resins can be used alone, but in order to further improve durability, they can be used in combination with Sin, Tin2.
A mixed material with a condensate of a metal alkoxy compound that can form a film mainly composed of In2O3 and ZrO2 is suitable.

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.

1 Examples of the present invention will be described below.

Example 1 1 part by weight of the bisazo compound represented by Compound No. I-1 above as a charge generating substance, and diallyl phthalate resin (trade name: DAP, manufactured by Osaka Soda Co., Ltd.) as a binder resin.
1 part by weight was mixed with 100 parts by weight of methyl ethyl ketone, and kneaded for 3 hours using a mixer to prepare a coating solution for the charge generation layer. Next, 1 part by weight of the hydrazone compound represented by Compound No. 1l-2 was added as a charge transport material, and polycarbonate resin (trade name Panrai L-1225 manufactured by Teijin Kabo) was used as a binder resin.
1 part by weight was dissolved in 6 parts by weight of dichloromethane to prepare a coating liquid for a charge transport layer. Next, a charge generation layer (I μm) and a charge transport layer (I 7 μm) were coated with the prepared coating liquids in this order on a polyester terephthalate film on which aluminum had been vapor-deposited, and a negatively charged photoreceptor having the configuration shown in FIG. 1 was formed. was created.

Example 2 The charge transport material of Example 1 was converted into the compound No. II -
32 except for the hydrazone compound shown in Example 1.
A photoreceptor was produced in the same manner as described above.

Example 3 The charge transport material of Example 1 was used as the compound No., If −
A photoreceptor was produced in the same manner as in Example 1 except that the hydrazone compound represented by No. 5 was used.

Example 4 The charge transport material of Example 1 was used as the compound No. U-8.
except for the hydrazone compound shown in Example 1.
A photoreceptor was produced in the same manner as described above.

Example 5 The charge transport material of Example 1 was converted into the compound No. II -
A photoreceptor was produced in the same manner as in Example 1 except that the hydrazone compound represented by No. 9 was used.

Comparative Example 1 The charge transport substance in Example 1 was changed to 1-phenyl-3(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-2-pyrazoline (ASPP>), and the other conditions were the same as in Example 1. A photoreceptor was produced.

Comparative Example 2 The charge transport material in Example 1 was changed to p-diethylaminobenzaldehyde-diphenylhydrazone (ABPH),
A photoreceptor was produced in the same manner as in Example 1 in other respects.

Comparative Example 3 A photoreceptor was produced in the same manner as in Comparative Example 2, except that the charge generating substance in Comparative Example 2 was changed to a bisazo compound represented by the following formula (i).

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 of the photoreceptor (volts) is -6.0 kV in the dark.
This is the initial surface potential when the photoreceptor surface is negatively charged by performing corona discharge for 10 seconds, and the surface potential when the photoreceptor surface is then held in the dark for 2 seconds with corona discharge stopped, V, (
volts), and then apply an illuminance of 2L to the photoreceptor surface.
The time it takes for V to be halved after being irradiated with ux white light (
seconds) was determined, and the half-attenuation exposure amount E was determined as 2 (Lux·seconds). Further, the surface potential when the surface of the photoreceptor was irradiated with white light of 21 μχ for 10 seconds was defined as the residual potential Vr (volt). Furthermore, the half-attenuation exposure amount of monochromatic light of 550 nm E 1y2
(550) and the half-attenuation exposure amount E of monochromatic light of 650 nm,
/2 (650) ratio is red reproducibility E, 72 (650)
/ E , y2 (550). El, □ (65
The larger the value of 0)/EI72 (550), the better the red color reproducibility.

The measurement results are shown in Table 1.

5 Table 1 As seen in Table 1, Examples 1 to 5 are the same as Comparative Examples 1 to 3.
Although the surface potential is the same compared to that of , the residual potential and half-attenuation exposure amount are clearly improved, and the red color reproducibility is also good. Cheerful.

Example 6 1 part by weight of the bisazo compound represented by Compound No. I-1 as a charge-generating substance and 2 parts by weight of diallyl chloride resin (trade name: DAP, manufactured by Osaka Soda) as a binder resin. , and 150 parts by weight of methyl ethyl ketone, and kneaded for 3 hours using a mixer to prepare a coating solution to prepare a coating solution for the charge generation layer. Next, 1 part by weight of the hydrazone compound represented by Compound No. II2 was used as a charge transport substance, and polyarylate resin (trade name: U Polymer P-5001, manufactured by Unitika) was used as a binder resin.
．． A coating liquid for a charge transport layer was prepared by dissolving 5 parts by weight of the 5 parts by weight in 9 parts by weight of dichloromethane. Next, the prepared coating liquids were applied in the order of a charge transport layer (I 8 μm) and a charge generation layer (I μm) onto a polyester telescrate film on which aluminum had been vapor-deposited, and a surface coating layer was further formed thereon. A positively charging photoreceptor having the configuration shown in FIG. 2 was prepared.

Example 7 The charge transport material of Example 6 was converted into the compound No. II -
A photoreceptor was produced in the same manner as in Example 6 except that the hydrazone compound shown in No. 3 was used.

Example 8 The charge transport material of Example 6 was used as the compound No. 1l-5.
except for the hydrazone compound shown in Example 6.
A photoreceptor was produced in the same manner as described above.

Example 9 The charge transport material of Example 6 was converted into the compound No. II -
A photoreceptor was produced in the same manner as in Example 6 except that the hydrazone compound represented by No. 8 was used.

Example 10 The charge transport material of Example 6 was converted into the compound No. II -
A photoreceptor was produced in the same manner as in Example 6 except that the hydrazone compound represented by No. 9 was used.

Comparative Example 4 The charge transport substance in Example 6 was changed to 1-phenyl-3(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-2-pyrazoline (ASPP), and the other conditions were the same as in Example 6. A photoreceptor was produced.

Comparative Example 5 The charge transport material in Example 6 was changed to p-diethylaminobenzaldehyde-diphenylhydrazone (ABPH),
A photoreceptor was produced in the same manner as in Example 6 in other respects.

Comparative Example 6 A photoreceptor was produced in the same manner as in Comparative Example 5, except that the charge generating substance in Comparative Example 5 was changed to the bisazo compound shown in formula (i) above.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester r SP -4'28° 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 the surface potential is Vd when the photoreceptor surface is then held in the dark for 2 seconds with corona discharge stopped.
(volts), and then the illuminance 2 on the photoreceptor surface.
Calculate the time (seconds) required for Vd to be halved after irradiating Luχ white light.Half-attenuation exposure amount E l/2 (Luχ・sec)
And so. Further, the surface potential when the surface of the photoreceptor was irradiated with white light of 2 Luχ for 10 seconds was defined as the residual potential vr (volt). Furthermore, the half-attenuation exposure amount E l of monochromatic light of 550 nm
/2 (550) and the 9 half-attenuation exposure amount E1/2 (650) of monochromatic light of 650 nm was defined as the red color reproducibility E172 (650) /E, 2 (550). E, y2 (650) / E l/2 (550)
The larger the value, the better the red color reproducibility.

The measurement results are shown in Table 2.

Table 2 As seen in Table 2, Examples 6 to 10 are compared to Comparative Examples 4 to 10.
Although the surface potential is the same compared to No. 6, the residual potential and half-attenuation exposure amount are clearly improved, and red color reproducibility is also good. The gender is obvious.

Example 11 The charge transport material of Example 1 was combined with the compound No. III
A photoreceptor was produced in the same manner as in Example 1 except that the stilbene compound represented by -6 was used.

Example 12 The charge transport material of Example 1 was combined with the compound No. III
A photoreceptor was produced in the same manner as in Example 1 except that the stilbene compound represented by -7 was used.

Example 13 The charge transport material of Example 1 was converted into the compound No. III -
A photoreceptor was produced in the same manner as in Example 1 except that the stilbene compound represented by No. 11 was used.

Example 14 The charge transport material of Example 1 was used as the compound No. 1ll-1.
A photoreceptor was produced in the same manner as in Example 1 except that the stilbene compound represented by No. 4 was used.

The electrophotographic properties of the photoreceptor thus obtained were measured in the same manner as in Examples 1 to 5 using an electrostatic recording paper tester rSP-428J manufactured by Kawaguchi Electric.

The measurement results are shown in Table 3. In Table 3, the measurement results of Comparative Examples 1 to 3 are also listed for comparison.

Table 3 As seen in Table 3, Examples 11 to 14 are compared to Comparative Example 1.
Although the surface potential is the same as in 3., the residual potential and half-attenuation exposure amount are clearly improved, and the red color reproducibility is also good, demonstrating the advantages of combining the bisazo compound and stilbene compound of this invention. The gender is obvious.

Example 15 The charge transport material of Example 6 was used as the compound No. nI −
A photoreceptor was produced in the same manner as in Example 6 except that the stilbene compound represented by No. 6 was used.

Example 16 The charge transport material of Example 6 was used as the compound No. m-7.
The stilbene compound represented by
A photoreceptor was produced in the same manner as described above.

Example 17 The charge transport material of Example 6 was used as the compound No. III-
A photoreceptor was produced in the same manner as in Example 6 except that the stilbene compound represented by No. 11 was used.

Example 18 The charge transport material of Example 6 was used as the compound No. III-
A photoreceptor was produced in the same manner as in Example 6 except that the stilbene compound represented by No. 14 was used.

The electrophotographic properties of the photoreceptors thus obtained were measured in the same manner as in Examples 6 to 1o using an electrostatic recording paper tester RSP-428J manufactured by Kawaguchi Electric.

The measurement results are shown in Table 4. In addition, Table 4 shows 3 also reposted the measurement results of Comparative Examples 4 to 6 for comparison.

Table 4 As seen in Table 4, Examples 15 to 18 are compared to Comparative Example 4.
The surface potential is the same as that of 6 to 6, but the residual potential and half-attenuation exposure amount are clearly improved, and the red color reproducibility is also good, demonstrating the advantages of combining the bisazo compound and stilbene compound of this invention. The gender is obvious.

〔Effect of the invention〕

According to this invention, the bisazo compound represented by the general formula (I) is used as the charge generating substance, and the hydrazone compound represented by the general formula (II) or the bisazo compound represented by the general formula (I) is used as the charge transport substance. By using the stilbene compound shown above, it is possible to obtain a photoreceptor for electrophotography for copying machines that has high sensitivity even when charged positively and negatively and has excellent red reproducibility.

[Brief explanation of drawings]

1 and 2 are conceptual sectional views showing different embodiments of the photoreceptor of the present invention. 1 conductive substrate, 2 charge generation layer, 3 charge transport layer, 4
a, 4b photosensitive layer, 5 surface coating layer. Shoe size field □ Very old hat

Claims (1)

[Claims] 1) a charge generation layer comprising an organic material on a conductive substrate;
In an electrophotographic photoreceptor equipped with a charge transport layer, the charge generation layer contains at least one bisazo compound represented by the following general formula (I) as a charge generation substance, and the charge transport layer contains at least one of the bisazo compounds represented by the following general formula (I). A photoreceptor for electrophotography, characterized in that it uses at least one kind of hydrazone compound represented by general formula (II). 2) a charge generation layer comprising an organic material on a conductive substrate;
In an electrophotographic photoreceptor equipped with a charge transport layer, the charge generation layer contains at least one bisazo compound represented by the following general formula (I) as a charge generation substance, and the charge transport layer contains at least one of the bisazo compounds represented by the following general formula (I). An electrophotographic photoreceptor comprising at least one stilbene compound represented by general formula (III). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) [In formula (I), Z represents an optionally substituted heterocyclic residue, R_1 represents an optionally substituted alkyl group, and R_
2 represents any one of a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester group, and an acyl group. ] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) [In formula (II), A represents any of the following optionally substituted aryl groups or heterocyclic groups, and R_3 is each of the following Represents either an alkyl group or an aryl group that may be substituted, R_4 represents a hydrogen atom, a halogen atom, or any of the following optionally substituted alkyl or aryl groups, and n represents 0 or 1
represents. ] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (III) [In formula (III), B represents any of the following optionally substituted aryl groups and heterocyclic groups, and R_5
and R_6 represents any of the following optionally substituted alkyl groups, aryl groups, and heterocyclic groups,
m represents 0 or 1. ]