JP2623663B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member having a layer configuration in which a charge generation layer and a charge transport layer are functionally separated.

2. Description of the Related Art Conventionally, electrophotographic photoreceptors include a photoconductive layer having a single layer and a stacked type. In recent years, an organic photoconductive substance has been bound with a resin or the like as a photoconductive layer, and a charge transporting layer has been formed. Various proposals have been made for an organic electrophotographic photoreceptor having a layer configuration separated from the charge generation layer by function, and various charge generation materials and charge transport materials have been proposed. For example, as the charge generation material, a polycyclic quinone pigment,
Perylene pigments, indigo pigments, bisbenzimidazole pigments, quinacridone pigments, phthalocyanine pigments, monoazo pigments, bisazo pigments, trisazo or polyazo pigments and the like are known, and as the charge transport material, amine compounds, hydrazone compounds, pyrazoline compounds, Oxazole compounds, oxadiazole compounds, stilbene compounds, carbazole compounds and the like are known. Various proposals have been made to use these charge generation materials and charge transport materials in combination. (For example, see JP-A-54-22
No. 834, No. 57-205742 to 205747, No. 57-204042 to 20405
No. 3, 57-197544-197551, 58-122544-122551
JP-A-61-67865, JP-A-61-124949, and 6
No. 1-132953, No. 61-129653, No. 61-221751,
Problems to be Solved by the Invention By the way, in order to obtain satisfactory electrophotographic characteristics in a laminated electrophotographic photoreceptor in which the function is separated into a charge generation layer and a charge transport layer, 1. It is necessary that the condition that the charge generation material efficiently generates charge with respect to the absorbed light, and 2. The condition that the generated charge is efficiently injected and transported into the charge transport material is satisfied. . That is, 1
If the condition (2) is not satisfied, a satisfactory optical response cannot be obtained even if the condition (2) is satisfied.

Further, when the electrophotographic photoreceptor has a charge generating layer and a charge transporting layer laminated in this order, and the light irradiation is performed from the charge transporting layer side, as a condition to be provided in order to obtain high sensitivity, a charge must be satisfied. It is necessary that the transport layer is sufficiently transparent to light active in the charge generation layer.

In order to prepare an electrophotographic photoreceptor using a charge generation material and a charge transport material, the photoreceptor satisfies the above-described conditions, and has sensitivity, an accepting potential, a potential holding property, a potential stability,
Materials that must be satisfied in all respects, such as electrophotographic characteristics such as residual potential and spectral characteristics, use characteristics such as strength, durability, and stain resistance, and manufacturing stability and quality stability when manufacturing by coating. Must choose. However, it is very difficult to select a combination of materials that satisfies all of these points, and the above-mentioned conditions are not sufficiently satisfied for the combination of the charge generation material and the charge transport material that has been conventionally proposed. Satisfaction has not been obtained.

The present invention has been made in view of the above circumstances, and by finding a combination of materials that satisfies all of the items required for an electrophotographic photosensitive member, an excellent electrophotographic photosensitive member has been developed. It is intended to provide.

Means and Solution for Solving the Problems The object of the present invention is to provide a charge generation material for a charge generation layer having the following general formula (I) [Wherein A is the following general formula (1), (2), (3),
(4) or (5) (Wherein, X represents an atomic group necessary for forming a polynuclear aromatic ring or heterocyclic ring by condensing with a benzene ring, and R ₆ and R ₇ represent
Each represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group or a heterocyclic group, or a group which forms a cyclic amino group by bonding together with a nitrogen atom; R ₈ and R ₉ represents an alkyl group, an aralkyl group or an aryl group each of which may be substituted, Y represents a divalent hydrocarbon group), and _one of R ₁ and R ₂ is A hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group or a nitro group, and the other represents an alkyl group, an alkoxy group, a halogen atom, a cyano group or a nitro group]. The following general formula (II) is used as the charge transport material of the transport layer. (In the formula, R ₃ represents a hydrogen atom, an alkyl group or an alkoxy group, and R ₄ and R ₅ are, when R ₃ represents a hydrogen atom,
Each represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group or a substituted amino group, and when R ₃ represents an alkyl group or an alkoxy group, a hydrogen atom, a methyl group, an alkoxy group, a halogen atom, Which represents an alkoxycarbonyl group or a substituted amino group).

That is, the electrophotographic photoreceptor of the present invention, on a conductive substrate,
A photosensitive layer comprising a charge generation layer and a charge transport layer, wherein the charge generation layer contains the bisazo pigment represented by the general formula (I), and the charge transport layer is a compound represented by the general formula (II)
Characterized by containing a benzidine compound represented by the formula:

 Hereinafter, the present invention will be described in detail.

In the present invention, the bisazo pigment contained in the charge generation layer is represented by the above general formula (I).
Is a group represented by the following general formula (1), (2), (3), (4) or (5).

(Wherein, X represents an atomic group necessary for forming a polynuclear aromatic ring or heterocyclic ring by condensing with a benzene ring, and R ₆ and R ₇ represent
Each represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group or a heterocyclic group, or a group which forms a cyclic amino group by bonding together with a nitrogen atom; R ₈ and R ₉ represents an alkyl group, an aralkyl group or an aryl group which may be substituted, and Y represents a divalent hydrocarbon group. Specific examples of these bisazo pigments include the following compounds.

In the present invention, the particle size of these bisazo pigments is 2 μm.
m or less.

Examples of the binder resin for dispersing the bisazo pigment include well-known binder resins such as polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylate polymer or copolymer, vinyl acetate polymer or copolymer, cellulose ester or ether, and polybutadiene. , Polyurethane, epoxy resin and the like are used.

On the other hand, as the charge transporting material in the charge transporting layer, a benzidine compound represented by the general formula (II) is used. Specific examples of the compound represented by the general formula (II) include the following. Can be

Since these compounds have no film forming property by themselves, they are used in combination with a resin having good film forming property. Examples of the resin that can be used include polycarbonate, polyacrylate, polyester, polyarylate, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylate, and styrene-methacrylate copolymer. Of these, polycarbonate is preferred.

The method for preparing the electrophotographic photoreceptor of the present invention will be described in more detail. First, the charge generation layer is formed by dispersing a bisazo pigment in a binder resin solution and applying the solution. As the dispersing means, those usually used such as a ball mill, a roll mill, a sand mill, and an attritor can be used. The compounding ratio of the bisazo pigment and the binder resin is 40: 1 to
1: 4, preferably 20: 1 to 1: 2. If the ratio of the bisazo pigment is too high, the stability of the coating solution will decrease, and if it is too low, the sensitivity will decrease. As a solvent for the binder resin, any solvent can be used as long as it has solubility, but it is desirable to select a solvent having good pigment dispersibility. Further, a plurality of solvents may be used in combination.

The charge transport layer is formed by dissolving a benzidine compound represented by the general formula (II) and a film-forming resin in a solvent that dissolves both, and applying the same. The mixing ratio of the former and the latter is 5: 1 to 1: 5, preferably 3: 1 to 1: 3. If the former ratio is too high, the mechanical strength of the charge transporting layer will decrease, and if it is too low, the sensitivity will decrease.

In the electrophotographic photoreceptor of the present invention, the layer configuration of the photosensitive layer formed on the conductive substrate may be such that a charge transport layer may be provided on the charge generation layer, or the charge transport layer may be provided on the charge transport layer. A generating layer may be provided. The thickness of the charge generation layer is 0.05 to 5 μm, and the thickness of the charge transport layer is 5 to 50 μm.
In the electrophotographic photoreceptor of the present invention, it is preferable to provide a charge injection blocking layer between the photosensitive layer and the conductive substrate.

Examples Next, the present invention will be described with reference to Examples and Comparative Examples.

Example 1 1 part by weight of a polyvinyl butyral resin (trade name: BLX, manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 40 parts by weight of cyclohexanone, and 3 parts of Exemplified Compound I-10 as a charge generating material were dissolved therein.
Parts by weight were added and then well dispersed in a paint shaker. The resulting dispersion was applied on an aluminum sheet using an applicator and dried to form a charge generation layer. The film thickness after drying was 0.2 μm.

Next, on this charge generation layer, 1 part by weight of Exemplified Compound II-3 as a charge transport material and 1 part of a polycarbonate resin (trade name: Lexan 145, manufactured by GE, molecular weight: 35,000 to 40,000)
Parts by weight, a homogeneous solution consisting of 15 parts by weight of dichloromethane
It was applied by an applicator and dried to form a charge transport layer. The film pressure after drying was 20 μm.

The electrophotographic photoreceptor sheet prepared in this manner is used as an electrostatic copying paper tester (SP-428, Kawaguchi Electric Works Co., Ltd.)
) Was used to evaluate the characteristics as follows. First,-
After a negative charge by applying a corona discharge of 6 KV, the device is left in a dark place for 2 seconds, the surface potential Vo (volt) at that time is measured, and then a light is applied using a tungsten lamp so that the illuminance of the surface becomes 5 lux. Irradiation was performed to determine the time required for the surface potential to become 1/2 of Vo, and the exposure amount E1 / 2 (lux · sec) was calculated. Vo = -1030 V and E 1/2 = 1.5 lux · sec.

Examples 2 to 12 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the materials shown in Table 1 were used instead of the charge generation material and the charge transport material in Example 1. Was evaluated. The results are shown in Table 1.

Comparative Example 1 Example 1 was repeated except that the compound represented by the following structural formula (III) was used as the charge transporting material.
An electrophotographic photoreceptor was prepared in the same manner as in 1. and evaluated in the same manner.

Comparative Example 2 Example 4 was repeated except that the compound represented by the structural formula (III) was used as the charge transporting material.
An electrophotographic photoreceptor was prepared in the same manner as in 1. and evaluated in the same manner.

Comparative Example 3 Example 7 was repeated except that the compound represented by the above structural formula (III) was used as the charge transporting material.
An electrophotographic photoreceptor was prepared in the same manner as in 1. and evaluated in the same manner.

Comparative Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 9 except that the compound represented by the following structural formula was used as the charge transport material, and the evaluation was performed in the same manner.

Table 2 shows the results.

Effect of the Invention In the present invention, by combining the charge generation layer containing the bisazo pigment and the charge transport layer containing the benzidine compound, the chargeability is good, the potential decay due to light irradiation is fast, and the sensitivity is high. The electrophotographic photoreceptor has a high potential, has little electric field dependence of potential decay, and is easily light attenuated even at a relatively low potential. That is, an electrophotographic photosensitive member having no trailing potential and having almost no residual potential can be obtained. Further, the electrophotographic photoreceptor of the present invention has good potential stability, little dependence on temperature and humidity, furthermore, extremely little light fatigue, has no reduction in chargeability by light, so-called optical memory effect, and is very usable. It has the property of being easy.

The electrophotographic photoreceptor of the present invention is effectively used in an electrophotographic copying machine, but is also applicable to various printers, microfilm readers, electrophotographic plate making systems and the like to which xerography technology is applied.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumiaki Taho 1600 Takematsu, Fuji Xerox Co., Ltd., Fuji Xerox Co., Ltd. In-house (56) References JP-A-63-113467 (JP, A) JP-A-61-132955 (JP, A) JP-A-63-80261 (JP, A) JP-A-1-197759 (JP, A) JP-A-1-257957 (JP, A)

Claims (1)

(57) [Claims] 1. A laminated electrophotographic photosensitive member having a photosensitive layer comprising a charge generation layer and a charge transport layer on a conductive substrate, wherein the charge generation layer has the following general formula (I): [Wherein A is the following general formula (1), (2), (3),
(4) or (5) (Wherein, X represents an atomic group necessary for forming a polynuclear aromatic ring or heterocyclic ring by condensing with a benzene ring, and R ₆ and R ₇ represent
Each represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group or a heterocyclic group, or a group which forms a cyclic amino group by bonding together with a nitrogen atom; R ₈ and R ₉ represents an alkyl group, an aralkyl group or an aryl group each of which may be substituted, Y represents a divalent hydrocarbon group), and _one of R ₁ and R ₂ is A hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group or a nitro group, and the other represents an alkyl group, an alkoxy group, a halogen atom, a cyano group or a nitro group]. The transport layer has the following general formula (II) (In the formula, R ₃ represents a hydrogen atom, an alkyl group or an alkoxy group, and R ₄ and R ₅ are, when R ₃ represents a hydrogen atom,
Each represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group or a substituted amino group, and when R ₃ represents an alkyl group or an alkoxy group, a hydrogen atom, a methyl group, an alkoxy group, a halogen atom, (Indicating an alkoxycarbonyl group or a substituted amino group).