JP2591168B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoconductor, and more particularly, to an electrophotographic photoconductor using a novel charge generating substance.

[Conventional technology]

Conventionally, photoconductors for electrophotography (hereinafter also referred to as photoconductors)
Examples of the photosensitive material include inorganic photoconductive substances such as selenium or a selenium alloy, inorganic photoconductive substances such as zinc oxide and cadmium sulfide dispersed in a resin binder, poly-N-vinylcarbazole or polyvinylanthracene. And organic photoconductive substances such as phthalocyanine compounds and bisazo compounds, etc. dispersed in a resin binder or vacuum-deposited.

The photoreceptor must have the function of retaining surface charges in the dark, the function of receiving light to generate charges, and the function of receiving light and transporting charges. A so-called single-layer type photoreceptor that combines functions, a layer that mainly contributes to charge generation, and a layer that separates functions into a layer that contributes to the retention of surface charges in a dark place and the charge transport during photoreception. There is a laminated photoreceptor. For image formation by electrophotography using these photoconductors, for example, the Carlson method is applied. Image formation by this method involves charging a photoreceptor by corona discharge in a dark place, forming an electrostatic latent image such as a character or picture of an original on the charged photoreceptor surface, and forming the electrostatic latent image After the toner image is transferred, the photoreceptor is subjected to charge elimination, removal of residual toner, light charge elimination, etc., and then reused. Is done.

In recent years, electrophotographic photoreceptors using organic materials have been put to practical use due to advantages such as flexibility, thermal stability, and film forming properties. For example, poly-N-vinylcarbazole and 2,2
A photoreceptor comprising 4,7-trinitrofluoren-9-one (described in U.S. Pat. No. 3,484,237), a photoreceptor containing an organic pigment as a main component (described in JP-A-47-37543), And a photoreceptor having a eutectic complex comprising a dye and a resin as a main component (described in JP-A-47-10785). Furthermore, many hydrazone compounds, bisazo compounds and the like have been put to practical use.

[Problems to be solved by the invention]

As described above, organic materials have many advantages over inorganic materials, but at the same time, at the same time, those that sufficiently satisfy all the characteristics required for electrophotographic photoreceptors have not yet been obtained. In particular, there was a problem in light sensitivity and characteristics in repeated continuous use.

The present invention has been made in view of the above points,
By using a new organic material that has never been used as a charge generating material in the photosensitive layer, the purpose is to provide a photoreceptor for copying machines and printers with high sensitivity and excellent repetition characteristics. I do.

[Means for solving the problem]

According to the present invention, the above-described object has photosensitive layers 20, 21, and 22 containing at least one of the azo compounds represented by the following general formula (I): [In the formula (I), A is a coupler residue represented by the general formulas (II) to (VII), and R ₁ and R ₆ are a hydrogen atom, a halogen atom, a nitro group or an alkyl group which may be substituted, An alkoxy group, R ₂ and R ₅ are a hydrogen atom, a halogen atom, or an optionally substituted alkyl group or an alkoxy group, and R ₃ and R ₄ are a hydrogen atom or an optionally substituted alkyl group or an aryl group, respectively. .

In the formulas (II) to (VII), Z is a residue condensed with a benzene ring to form an aromatic polycyclic or heterocyclic ring, X ₁ is a hydrogen atom or COOR ₇ or CONR ₈ R ₉ (R ₇ , R ₈ And R
₉ represents a hydrogen atom, an optionally substituted alkyl or aryl group or a heterocyclic group), X ₂ and
X ₅ are each an optionally substituted alkyl group, an aryl group or a heterocyclic group, X ₃ and X ₆ represents a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester group or an acyl group, X ₄ and X ₁₁ represents a hydrogen atom, an optionally substituted alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group, an aryl group or a heterocyclic group,
X ₇ and X ₈ each represent a hydrogen atom, a halogen atom, a nitro group or an optionally substituted alkyl group or an alkoxy group, and X ₉ represents an optionally substituted alkyl group, an aryl group, a carboxyl group or an ester group. , X ₁₀ represents an optionally substituted aryl group or a heterocyclic group, Y represents a residue forming an aromatic heterocyclic ring. ] Is achieved.

The compound represented by the general formula (I) can be prepared by diazotizing an amino compound represented by the following general formula (VIII) by a conventional method, and a corresponding solvent and an appropriate solvent (for example, N, N dimethylformamide, By performing a coupling reaction in dimethyl sulfoxide or the like, the compound can be easily synthesized.

[In the formula (VIII), R ₁ and R ₆ represent a hydrogen atom, a halogen atom, a nitro group or an optionally substituted alkyl group or an alkoxy group, and R ₂ and R ₅ represent a hydrogen atom, a halogen atom or a substituted each. And R ₃ and R ₄ represent a hydrogen atom or an optionally substituted alkyl or aryl group, respectively. The compound represented by the general formula (I) is as follows.

[Action] There is no known example of using the azo compound represented by the general formula (I) in a photosensitive layer. The present inventors have conducted intensive studies on various organic materials in order to achieve the above object, and as a result of conducting a number of experiments on these azo compounds, the technical elucidation has not yet been sufficiently completed. It has been found that the use of a specific azo compound represented by the above general formula (I) as a charge generating material is extremely effective in improving electrophotographic characteristics, and a photoconductor having high sensitivity and excellent repetition characteristics is obtained. It was reached.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

The photoreceptor of the present invention contains the compound represented by the general formula (I) in the photosensitive layer. Depending on how these compounds are applied, the photoreceptor shown in FIG. 1, FIG.
It can be used as shown in the figure.

1 to 3 are conceptual sectional views of the photoreceptor of the present invention.
1 is a conductive substrate, 20, 21 and 22 are photosensitive layers, 3 is a charge generation material, 4 is a charge generation layer, 5 is a charge transport material, 6 is a charge transport layer, and 7 is a coating layer.

FIG. 1 shows a photosensitive layer 20 (usually referred to as a single-layer type photoreceptor) in which a compound of the general formula (I), which is a charge generating substance 3, and a charge transporting substance 5 are dispersed in a resin binder on a conductive substrate 1. Configuration) is provided.

FIG. 2 shows a laminate of a charge generation layer 4 containing a compound of the general formula (I), which is a charge generation substance 3, on a conductive substrate 1 and a charge transport layer 6 mainly composed of a charge transport substance 5. (Usually referred to as a laminated photoreceptor).

FIG. 3 shows the reverse layer configuration of FIG. In this case, it is general to further provide a coating layer 7 to protect the charge generation layer 4.

The reason why the two types of layer constitutions shown in FIGS. 2 and 3 are adopted is that even if the layer constitution shown in FIG. This has not been found, and therefore, the layer configuration shown in FIG. 3 is required at this stage as a positive charging type photoconductor.

The photoreceptor shown in FIG. 1 can be produced by dispersing a charge generating substance in a solution in which a charge transporting substance and a resin binder are dissolved, and applying this dispersion to a conductive substrate.

In the photoreceptor shown in FIG. 2, a dispersion obtained by dispersing particles of a charge generating substance in a solvent or a resin binder on a conductive substrate was applied and dried, and the charge transporting substance and the resin binder were dissolved thereon. It can be produced by applying and drying a solution.

The photoreceptor shown in FIG. 3 is obtained by applying a solution in which a charge transporting substance and a resin binder are dissolved on a conductive substrate, drying the solution, and then dispersing the particles of the charge generating substance in a solvent or a resin binder. It can be produced by applying and drying a liquid and further forming a coating layer.

The conductive substrate 1 serves as an electrode of the photoreceptor and serves as a support for the other layers, and may be cylindrical, plate-like, film-like, or made of aluminum, stainless steel, nickel, or the like. A conductive material may be applied to metal, glass, resin, or the like.

The charge generation layer 4 is formed by applying a material in which particles of the charge generation material 3 represented by the compound represented by the general formula (I) are dispersed in a resin binder, and generates light by receiving light. In addition, it is important that the charge generation efficiency is high and at the same time, the generated charge is injected into the charge transporting layer 6 and the coating layer 7. The charge generation amount can be a charge generation material as a main component, to which a charge transport material or the like is added. As the resin binder, polycarbonate, polyester, polyamide, polyurethane, vinyl chloride, epoxy, silicone resin, diallyl phthalate resin, butyral resin, polymers and copolymers of methacrylic acid esters can be used in appropriate combination. .

The charge transport layer 6 is formed by applying a material in which a hydrazone compound, a pyrazoline compound, a stilbene compound, a triphenylamine compound, an oxazole compound, an oxadiazole compound, or the like is dissolved and dispersed as an organic charge transport material in a resin binder. In a dark place, it functions as an insulator layer to retain the charge of the photoreceptor, and at the time of receiving light, exhibits a function of transporting charge injected from the charge generation layer. Examples of the resin binder include polycarbonate, polyester, polyamide, polyurethane, epoxy, silicone resin, and methacrylate polymers and copolymers.

The coating layer 7 has a function of receiving and holding the charge of the corona discharge in a dark place, and has a performance of transmitting light which the charge generation layer is sensitive to. It is necessary that the surface charge is neutralized and eliminated by receiving the generated charge. As the coating material, an organic insulating film forming material such as polyester and polyamide can be applied. In addition, these organic materials and glass resin, SiO
It is also possible to use a mixture of an inorganic material such as ₂ , a metal alkoxy compound having a film-forming ability, and further a material such as a metal or a metal oxide that reduces electric resistance. The coating material is not limited to an organic insulating film forming material, but may be an inorganic material such as SiO _2, or a metal, a metal oxide, or the like, formed by a method such as evaporation or sputtering. As described above, it is desirable that the coating material is as transparent as possible in the wavelength region where the light absorption of the charge generating substance is maximum.

Although the thickness of the coating layer itself depends on the composition of the coating layer, it can be set arbitrarily within a range where adverse effects such as an increase in residual potential do not occur when repeatedly used continuously.

 Hereinafter, examples of the present invention will be described.

Example 1 100 parts by weight of a polyester resin (trade name: Byron 200: manufactured by Toyobo) was mixed with 50 parts by weight of the compound represented by Compound No. 1 and 1-phenyl-3- (p-diethylaminostyryl)-
100 parts by weight of 5- (p-diethylaminophenyl) -2-pyrazoline (ASPP) and a solvent of tetrahydrofuran (THF) were kneaded with a mixer for 3 hours to prepare a coating solution, and an aluminum-evaporated polyester film (Al −
A photoreceptor was prepared by applying the solution on a PET) by a wire bar method so that the film thickness after drying was 15 μm.

Example 2 First, 100 parts by weight of p-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) and 100 parts by weight of a polycarbonate resin (trade name: Panlite L-1250: manufactured by Teijin) were dissolved in methylene chloride, and a coating solution formed by aluminum deposition was used. It was applied on a polyester film substrate by a wire bar method, and a charge transport layer was formed so that the film thickness after drying was 15 μm. On the thus obtained charge transport layer, the compound
50 parts by weight of the compound represented by No. 2 and 50 parts by weight of a polyester resin (trade name: Byron 200, manufactured by Toyobo) and a THF solvent were kneaded with a mixer for 3 hours to prepare a coating solution, which was applied by a wire bar method. The charge generation layer was formed such that the film thickness after drying was 0.5 μm.

Example 3 In Example 2, the charge transport material was changed to ABPH,
Α-phenyl-4′-N, N- which is a stilbene compound
A charge transport layer was formed in the same manner as in Example 2 using dimethylaminostilbene, and a charge generation layer was further formed to prepare a photoreceptor.

Example 4 In Example 2, the charge transport material was changed to ABPH,
Tri (p-tolyl) which is a triphenylamine compound
A charge transport layer was formed in the same manner as in Example 2 using an amine, and a charge generation layer was further formed to prepare a photoreceptor.

Example 5 In Example 2, the charge transport material was changed to ABPH,
Using 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, which is an oxadiazole compound, a charge transport layer was formed in the same manner as in Example 2, and a charge generation layer was further formed. A photoreceptor was produced.

The electrophotographic characteristics of the photoreceptor thus obtained were measured using an electrostatic recording paper tester “SP-428” manufactured by Kawaguchi Electric.

The photoreceptor surface potential V _S (volts) is the initial surface potential when the surface of the photoreceptor is positively charged by performing +6.0 kV corona discharge for 10 seconds in a dark place. Then, the corona discharge is stopped. , The surface potential V _d (volts) when kept in a dark place for 2 seconds is measured, and then the time until the V _d is halved by irradiating the surface of the photoreceptor with white light having an illuminance of 2 lux (seconds)
Was determined and defined as a half-attenuation exposure amount E _1/2 (looks / second). The surface potential when white light having an illuminance of 2 lux was irradiated for 10 seconds was defined as a residual potential V _r (volt).

As can be seen from Table 1, Examples 1, 2, 3, 4, and 5 exhibited good half-attenuation exposure and residual potential.

Example 6 100 parts by weight of the compounds represented by the compounds No. 3 to No. 49 were kneaded with 100 parts by weight of a polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.) and a THF solvent by a mixer for 3 hours to prepare a coating solution. Prepared, approximately 0.
It was applied so as to have a thickness of 5 μm to form a charge generation layer. A coating solution of ABPH obtained by the same method as that prepared in Example 2 was applied thereon so as to have a thickness of about 15 μm to prepare a photoreceptor.

The electrophotographic characteristics of the photoreceptor thus obtained were measured using an electrostatic recording paper tester “SP-428” manufactured by Kawaguchi Electric. Table 2 shows the results.

The surface potential V _S of the photosensitive member (volts) is the initial surface potential when the corona discharge of -6.0kV was allowed negatively charged surface of the photosensitive member conducted for 10 seconds in the dark, followed by the state was discontinued corona discharge , The surface potential V _d (volts) when kept in a dark place for 2 seconds is measured, and then the time until the V _d is halved by irradiating the surface of the photoreceptor with white light having an illuminance of 2 lux (seconds)
Was determined and defined as a half-attenuation exposure amount E _1/2 (looks / second).

As can be seen from Table 2, the photoreceptors using the azo compounds Nos. 3 to 49 as the charge generating materials also exhibited good half-attenuation exposure amounts E1 _{/ 2} .

〔The invention's effect〕

According to the present invention, since the compound represented by the general formula (I) is used as a charge generating substance on a conductive substrate, a photosensitive member having high sensitivity and excellent repetition characteristics even in positive charging and negative charging can be obtained. Obtainable. Furthermore, if necessary, a coating layer can be provided on the surface to improve the durability.

[Brief description of the drawings]

1, 2 and 3 are conceptual sectional views showing different embodiments of the photoconductor of the present invention. DESCRIPTION OF SYMBOLS 1 ... Conductive base, 3 ... Charge generating substance, 4 ... Charge generating layer, 5 ... Charge transporting substance, 6 ... Charge transporting layer, 7 ...
Coating layer, 20, 21, 22 ... photosensitive layer.

Continuation of the front page (56) References JP-A-1-230573 (JP, A) JP-A-1-159661 (JP, A) JP-A-64-72166 (JP, A) JP-A-61-254948 (JP) , A) JP-A-64-96658 (JP, A)

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member having a photosensitive layer containing at least one of the azo compounds represented by the general formula (I). [In the formula (I), A is a coupler residue represented by the general formulas (II) to (VII), and R ₁ and R ₆ are a hydrogen atom, a halogen atom, a nitro group or an alkyl group which may be substituted, An alkoxy group, R ₂ and R ₅ are a hydrogen atom, a halogen atom, or an optionally substituted alkyl group or an alkoxy group, and R ₃ and R ₄ are a hydrogen atom or an optionally substituted alkyl group or an aryl group, respectively. . In the formulas (II) to (VII), Z is a residue condensed with a benzene ring to form an aromatic polycyclic or heterocyclic ring, X ₁ is a hydrogen atom or COOR ₇ or CONR ₈ R ₉ (R ₇ , R ₈ And R ₉ are
Each represents a hydrogen atom, an optionally substituted alkyl group or an aryl group or a heterocyclic group), X ₂ and X ₅ represent an optionally substituted alkyl group, an aryl group or a heterocyclic group, and X ₃ and X ₆ represents a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester group or an acyl group, and X ₄ and X ₁₁ represent a hydrogen atom, an optionally substituted alkyl group, cycloalkyl group, alkenyl group, aralkyl group, aryl Represents a group or a heterocyclic group, X ₇ and
X ₈ are each a hydrogen atom, a halogen atom, a nitro group or an optionally substituted alkyl or alkoxy group, X ₉ represents an optionally substituted alkyl group, an aryl group, a carboxyl group, an ester group, X ₁₀ Represents an aryl group or a heterocyclic group which may be substituted, and Y represents a residue forming an aromatic heterocyclic ring. ]