JPH07219251A - Electrophotographic photoconductor - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Laminated type with excellent chargeability and sensitivity, stable electrostatic characteristics for long-term repeated use, and a small amount of ozone generated for positive charging process. To provide a photoconductor for electrophotography. [Structure] Charge generation layer (CGL) and charge transport layer (CT)
One or more kinds of the same binders are contained in L), and polycarbonate Z is preferably used. A compound having an acceptor compound having an electron transporting ability in CGL and having a reduction potential value larger than that of the acceptor compound contained in CTL is preferable as the acceptor compound contained in CGL. The compound represented by the general formula (I) is used as an acceptor compound to be contained in CGL.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated type electrophotographic photoreceptor used in a copying machine, a printer or the like using an electrophotographic process.

[0002]

2. Description of the Related Art The electrophotographic process is based on the visualization of a latent image by electrostatic charge. Therefore, the electrophotographic photosensitive member used in the process has good chargeability and rapid surface irradiation by light irradiation. Potential decay is required. The properties required for these processes are reduced to a high dark resistance which is an intrinsic property value of the material, a good quantum efficiency of charge carrier generation and a high charge mobility. In order to satisfy these physical property values, a photoconductor composed of an inorganic compound such as selenium, selenium-tellurium alloy, or arsenic selenium has been adopted and has been used in many copying machines. However, these materials have some environmental safety problems, and are difficult to handle because they are used in an amorphous state. Furthermore, the number 1
Since it is necessary to vacuum-deposit a film having a film thickness of 0 μm, there are drawbacks such as high cost, and it cannot be said that the requirements for the photoconductor are sufficiently satisfied. To improve these drawbacks, a photoreceptor (OPC) using an organic material
Has been actively developed and put into practical use. Most of the practically used OPCs are of a function separation type in which a layer having a charge generation function (CGL) and a layer having an electron transport function (CTL) are laminated on a conductive substrate, and the functions are separated. By doing so, the selection range of materials is expanded,
Properties such as electrophotographic sensitivity, stability against repeated use, and mechanical strength have also been improved. The laminated OPC currently in practical use uses a donor compound having a hole transfer property as the CTL, and is therefore used in the negative charging process. However, negative charging has problems such as stability of corona discharge and generation of ozone, which is a factor of environmental pollution and chemical damage, as compared with positive charging, and positive charging of OPC is required. . There are several methods for making the OPC positively charged, and typical ones are: 1) a charge generation layer (CGL) and a charge transport layer (CTL) having an electron transporting ability are sequentially laminated on a conductive substrate. (Forward layer), 2) A charge transport layer (CTL) having a hole transport ability and a charge generation layer (CGL) are sequentially laminated on a conductive substrate (reverse layer), 3)
The charge-generating substance is dispersed in a binder together with the charge-transporting substance as needed (single layer).

The above method for positively charging the OPC is
Although each has its own advantages and disadvantages, the forward layer type of 1) is advantageous for higher sensitivity and higher durability. However, the forward layer type requires high mobility, and currently has the drawbacks of low sensitivity, large residual potential, and poor practicality. For example, JP-A-60-69657 and JP-A-60-
No. 222477, JP-A-61-148159, JP-A-61-225151, JP-A-63-70257, JP-A-1-206349, and JP-A-2-97964 disclose a positive charging process. Although a forward layer laminated type electrophotographic photoreceptor to be used has been proposed, there are still problems in terms of sensitivity, stability of electrophotographic characteristics against repeated use, and the like.

[0004]

The object of the present invention is to use in a positive charging process which is excellent in charging property and sensitivity, stable in electrostatic property against repeated use for a long period of time, and has a small ozone generation amount. An object is to provide a laminated type electrophotographic photoreceptor.

According to the present invention, an electrophotographic photosensitive member is formed by sequentially stacking a charge generation layer (CGL) and a charge transport layer (CTL) containing an acceptor compound having an electron transporting ability on a conductive substrate. In the body, the CGL and the CTL
Provided is an electrophotographic photoreceptor, which contains at least one kind of the same binder. Further, according to the present invention, there is provided a photoconductor for electrophotography, wherein the same binder contained in the CGL and CTL is polycarbonate Z. Further, according to the present invention, there is provided an electrophotographic photoconductor characterized in that the CGL contains an acceptor compound having an electron transporting ability. Further, according to the present invention, an acceptor compound is contained in the CGL and CTL,
Provided is a photoreceptor for electrophotography, wherein the value of the reduction potential of the acceptor compound contained in CGL is larger than the value of the reduction potential of the acceptor compound contained in CTL. Further, according to the present invention, the acceptor compound contained in the CGL has the following general formula (I):
There is provided an electrophotographic photoreceptor, which is a compound represented by any one of (VI) to (VI). The acceptor compound is an aromatic carbonyl compound represented by the general formula (I).

[Chemical 1] [In the formula, R ₃ and R ₄ are each a hydrogen atom, a halogen atom,
Substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted heterocyclic group, alkoxycarbonyl group, aryloxycarbonyl group, N-
Alkylcarbamoyl group, alkylcarbonyl group, arylcarbonyl group, cyano group, nitro group, alkoxy group, aryloxy group, amino group, or the following formula (I-
a) represents a group represented by a), and n and m each represent an integer of 1 to 3.

[Chemical 2] (However, A represents a hydrogen atom or an alkyl group, and at least one of B and D represents a substituted or unsubstituted phenyl group and the other represents a hydrogen atom.)]. The acceptor compound is a dicyanomethylene compound represented by the general formula (II).

[Chemical 3] [In the formula, R ₃ and R ₄ are each a hydrogen atom, a halogen atom,
Substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted heterocyclic group, alkoxycarbonyl group, aryloxycarbonyl group, N-
Alkylcarbamoyl group, alkylcarbonyl group, arylcarbonyl group, cyano group, nitro group, alkoxy group, aryloxy group, amino group, or the following formula (II
-A), wherein n and m are 1 to 3 respectively.
Indicates an integer.

[Chemical 4] (However, A represents a hydrogen atom or an alkyl group, and at least one of B and D represents a substituted or unsubstituted phenyl group and the other represents a hydrogen atom.)]. The acceptor compound is an α-cyanostilbene compound represented by the general formula (III).

[Chemical 5] (In the formula, R₁, R₂Is a substituted or unsubstituted phenyl group,
A substituted or unsubstituted aryl group, a substituted or unsubstituted
Polycyclic aromatic group or substituted or unsubstituted heterocyclic group
Represents ) An acceptor compound is represented by the general formula (IV).
Zol compound.

[Chemical 6] (In the formula, Ar ₁ and Ar ₂ represent a substituted or unsubstituted aromatic hydrocarbon group.) The vinylidene compound represented by the general formula (V) in which the acceptor compound is represented.

[Chemical 7] (In the formula, Ar ₁ and Ar ₂ represent a substituted or unsubstituted aromatic hydrocarbon group, and X represents a cyano group or an alkoxycarbonyl group.) The quinone compound represented by the general formula (VI) is an acceptor compound.

[Chemical 8] (In the formula, R ₁ is a hydrogen atom, a halogen atom, an alkyl group,
A substituted or unsubstituted phenyl group, R ₂ is a hydrogen atom, a halogen atom, an alkoxycarbonyl group, an N-alkylcarbamoyl group, a cyano group or a nitro group, and n is 1 to 3
Indicates an integer. That is, the inventors of the present invention have made extensive studies on positive charging of OPC, paying attention to a forward layer type laminated photoreceptor having a structure advantageous for high sensitivity and high durability, and at least one or more types of CGL and CTL. Of the same binder, using at least Polycarbonate Z as the same binder, containing an acceptor compound having an electron transporting ability in CGL, and containing an acceptor in CGL and CTL. It has been found that the above-mentioned object can be achieved by using an acceptor compound having a reduction potential value larger than that of the acceptor compound contained in CTL as the acceptor compound contained in CGL at that time. Furthermore, by using the compounds represented by the above general formulas (I) to (VI) as the acceptor compound to be contained in CGL, it is a practical problem that is a major problem of positively charged OPC of the forward layer. The inventors of the present invention have found that the drawbacks such as lack of sensitivity, large residual potential, and poor stability of electrophotographic characteristics against repeated use can be solved, and the present invention has been completed.

The electrophotographic photosensitive member of the present invention has the structure shown in FIG. 1, and comprises a charge generation layer (CG) on the conductive substrate 1.
L) 2 and charge transport layer (CTL) 3 can be sequentially laminated. At this time, as described above, CG
As an essential component of L, a charge generating substance and, if necessary, C
It is necessary to include at least one acceptor compound having a reduction potential higher than that of the acceptor compound used for the TL, and at least one binder identical to the binder used for the CTL. Polycarbonate Z is desirable as the same binder. Further, as an essential component of CTL, an acceptor compound having a reduction potential smaller than that of the acceptor compound in CGL having an electron transporting property, and at least CG
It is necessary to include the same binder as that used in L. In recent years, various electron transport materials have been proposed with the aim of developing positively charged OPC, but when a forward layer type laminated photoreceptor is used, the initial light decay is relatively fast, but the residual potential is very large and not practical. . It is said that one of the reasons is that the electron mobility of the electron-transporting material that has been announced depends largely on the electric field strength, and it is difficult to move in a low electric field (for example, Tanaka et al .; Polymer Prepri).
nts Japan 37 No. 3 1988). This is due to the molecular structure of the electron transport material, which is an essential problem of the material. In addition, it is considered that many electron transporting materials have a poor phase solubility with a binder as compared with the hole transporting material (for example, Kobayashi et al .; Ja.
pan Hardcopy '92 papers). According to the present invention, since the conduction carriers (electrons) generated in the CGL are effectively injected into the CTL and the generation efficiency of the conduction carriers in the CGL is improved, the conventional forward layer type The disadvantages of the positively charged photoreceptor, such as low sensitivity, high residual potential, and poor stability of electrophotographic characteristics against repeated use, can be solved. That is, in the forward layer structure of the present invention, CGL
The charge generating substance in the inside and the electron transporting substance in the CTL are CGL
By creating a situation where it is easy to contact at the / CTL interface, CT
By smoothly injecting conductive carriers (electrons) into L, and further by containing an acceptor compound in CGL as necessary, electrons are extracted from the conductive carriers generated in the charge generation substance. Promote
The number of effective free electrons can be increased to solve the above-mentioned problems. The conductivity σ of a substance is represented by Equation (1). σ = ne μ (1) where n is the number of conduction carriers, e is the elementary charge, and μ is the mobility. Among them, the mobility μ largely depends on the molecular structure of the electron transport material, the dispersion state in the CTL, and the like. The molecular structure of the electron transport material is a problem associated with molecular design and synthesis technology, but it can be achieved by appropriately selecting a binder to disperse the electron transport material in the CTL in a molecular state. Can be improved. Further, the number of conduction carriers n is basically the extinction coefficient of the charge generating substance,
Although depending on the state of aggregation, the number of traps, and the like, the n number can be increased by allowing an acceptor compound having an action of extracting an electron to exist in the vicinity of the charge generating substance.

The present invention is basically based on the findings described above. Many known electron-transporting materials have poor compatibility with the binder as described above, so that only a small amount can be added to the CTL, or the electron-transporting material often precipitates as crystals in the CTL. Further, among the binders, the present inventors have found that the polycarbonate Z is particularly compatible with many electron transport materials, and the use of the polycarbonate Z as a binder for the electron transport material solves the above problems. I found what I could do. Polycarbonate Z is bis (p-hydroxyphenyl) represented by the following general formula (VII).
Resin containing bisphenol A
It is distinguished from the polycarbonate A which is a resin containing [ester of 2,2-bis (p-hydroxyphenyl)] as a constituent unit.

[Chemical 9] Probably, since this polycarbonate Z is an amorphous polymer, it is considered that it has good compatibility with the electron transport material. Furthermore, the effect is further improved by including the polycarbonate Z in CGL. After coating CGL containing Polycarbonate Z and drying, Polycarbonate Z
When the CTL with the binder as a binder is laminated on the CGL, a part of the electron-transporting substance in the CTL is transferred to the CGL because of good compatibility, and the charge-generating substance and the electron-transporting material come into good contact with each other, so that the charge It is presumed that conduction electrons generated in the generated substance are smoothly injected into the electron transport material, CTL.
Further, it is also a preferred embodiment of the present invention to further contain an acceptor compound (electron transport material) in CGL, if necessary. The acceptor compound originally has a function of withdrawing electrons, and withdraws conduction electrons generated in the charge generating substance before recombination with holes, thereby increasing the number of conduction electrons. At this time, it is preferable that the value of the reduction potential of the acceptor compound contained in CGL is larger than the reduction potential of the electron transport substance (acceptor compound) in CTL (electron affinity is weak). When the value of the reduction potential of the acceptor compound contained in CGL is smaller than the value of the reduction potential of the acceptor compound contained in CTL (the electron affinity is strong), the electrons extracted from the charge generation substance are It is considered that the compound becomes trapped by the acceptor compound and becomes difficult to be injected into the CTL, resulting in poor sensitivity and increased residual potential.

As the acceptor compound used in CGL in the present invention, the compounds represented by the above-mentioned general formulas (I) to (VI) are used, and specifically, there are the following compounds. Examples of the compound represented by the general formula (I) are aromatic carbonyl compounds such as butyl m-benzylbenzoate and m-nitrobenzophenone. Examples of the compound represented by the general formula (II) include dicyanomethylene compounds such as α-nitrophenyl-β-dicyanostyrene and 9-dicyanomethylene-4-butoxycarbonylfluorenone, and general formula (I
The compounds represented by II) include α-cyanostilbene compounds as shown in Table 1, the compounds represented by the general formula (IV) include oxazole compounds as shown in Table 2, and the general formula (IV). Examples of the compound represented by V) include vinylidene compounds as shown in Table 3. Further, as shown by the general formula (VI), 2
-P-butylphenyl-p-benzoquinone and the like.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

[Table 3]

Examples of the charge generating substance used in the present invention include bisazo dyes, trisazo dyes, phthalocyanine dyes, quinacridone dyes, perylene dyes, polycyclic quinone dyes, indigo dyes, cyanine dyes, pyrylium dyes, bisbenzimidazole dyes, indus. Organic compounds such as len dyes, triarylmethane dyes, thiazine dyes, oxazine dyes, squarylium dyes, anthraquinone dyes, xanthene dyes, and amorphous selenium, trigonal selenium, selenium-arsenic alloys, selenium-tellurium alloys, cadmium sulfide, Examples thereof include inorganic compounds such as cadmium selenide, zinc oxide, and amorphous silicon. As the electron transport material used in the present invention, a quinone compound, a vinylidene dinitrile compound of a quinone compound, a fluorenone compound, a vinylidene dinitrile compound of a fluorenone compound, an α-cyanostilbene compound, a π electron system having a nitrile group Examples thereof include compounds and π-electron compounds having a nitro group. Polycarbonate Z is particularly preferable as the binder used in the present invention, and in addition, for example, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polystyrene, vinyl chloride resin,
Addition polymerization type of vinyl acetate resin, bisphenol A type polycarbonate, polyester resin, phenoxy resin, polyurethane resin, polyvinyl butyral resin, vinylidene chloride resin, silicone resin, fibrous resin, phenol resin, melamine resin, alkyd resin, epoxy resin, etc. Examples thereof include resins, polyaddition type resins, polycondensation type resins, and copolymer resins containing two or more of these repeating units. Examples of the conductive substrate used in the present invention include metal plates such as aluminum, nickel, copper, and stainless steel, metal drums or metal foils, plastic films coated with thin films of aluminum, tin oxide, copper iodide, or glass. To be

In the present invention, the composition of CGL is 10 to 400 parts by weight, preferably 25 to 100 parts by weight, and the acceptor compound is 0 to 200 parts by weight, based on 100 parts by weight of the charge generating substance. , Preferably 100 parts by weight. The film thickness of CGL is 0.05 to 10 μm, preferably 0.1 to 2 μm. Further, the composition of CTL is 25 to 400 parts by weight, preferably 50 to 200 parts by weight, based on 100 parts by weight of the electron transporting substance (acceptor compound). The thickness of the CTL is 5 to 60 μm, preferably 10 to 30 μm. Further, in the electrophotographic photoreceptor of the present invention, an undercoat layer may be provided between the conductive substrate and CGL for the purpose of improving charging property or adhesiveness. As these materials, polyamide resin, polyvinyl alcohol, polyvinylpyrrolidone, casein, polyimide and the like can be used in addition to the binder material. Furthermore, for the purpose of improving the surface properties and coating properties of the CTL, silicon oil such as phenylmethylsiloxane and dimethylsiloxane can be contained in the CTL. The electrophotographic photoreceptor of the present invention, each predetermined material is dissolved in an organic solvent, or a coating solution dispersed by a ball mill, ultrasonic waves, a homomixer, etc.,
It can be easily manufactured by applying it on a conductive substrate with a blade, a spray or the like and drying it.

[0014]

EXAMPLES The present invention will be described below with reference to examples, but the embodiments of the present invention are not limited thereby.

Example 1 X-type metal-free phthalocyanine (Fastogen Blu)
8120BS; manufactured by Dainippon Ink and Chemicals, Inc.) 0.6 g of a 10 wt% tetrahydrofuran solution 6 of polycarbonate Z
g, and 5.4 g of tetrahydrofuran, followed by ball milling, adding 48 g of tetrahydrofuran and stirring to 2
We prepared a coating solution of wt% and applied aluminum with a doctor blade onto a 75 μm thick polyester film vapor-deposited to a thickness of 1000 Å, and the film thickness after drying was 0.5 μm.
m CGLs were provided. Next, as an acceptor compound,
6 g of the electron transport material (B-1) having the following structural formula, 9 g of polycarbonate Z, and 0.009 g of silicon oil (KF50; manufactured by Shin-Etsu Chemical Co., Ltd.) were dissolved in 85 g of tetrahydrofuran to prepare a coating solution, and the coating solution was prepared on CGL with a doctor blade. A CTL having a thickness of 20 μm after coating and drying was laminated on the CGL to prepare an electrophotographic photoreceptor.

[Chemical 10]

Example 2 An electrophotographic photoreceptor was prepared under the same conditions as in Example 1 except that the electron transporting material (B-1) was replaced with the following compound (B-2). .

[Chemical 11]

Example 3 An electrophotographic photoreceptor under the same conditions as in Example 1 except that the electron transport material (B-1) in Example 1 was replaced with an electron transfer material (B-3) having the following structure. Was produced.

[Chemical 12]

Example 4 An electrophotographic photoreceptor under the same conditions as in Example 1 except that the electron transport material (B-1) in Example 1 was replaced by the electron transfer material (B-4) having the following structure. Was produced.

[Chemical 13]

Example 5 X-type metal-free phthalocyanine (Fastogen Blu)
8120BS; manufactured by Dainippon Ink and Chemicals, Inc.) 0.6 g of a 10 wt% tetrahydrofuran solution 6 of polycarbonate Z
g is an acceptor compound having the following structural formula (A-
1) After ball milling with 0.3 g and 5.4 g of tetrahydrofuran, 62.7 g of tetrahydrofuran
The mixture was added and stirred to prepare a coating solution of 2 wt%, and aluminum was applied onto a 75 μm thick polyester film vapor-deposited to a thickness of 1000 Å by a doctor blade to provide CGL having a film thickness after drying of 0.5 μm.

[Chemical 14] Next, the electron transport material (B-2) 6 used in Example 2 was used.
g, polycarbonate Z9g, silicone oil (KF5
(0; manufactured by Shin-Etsu Chemical Co., Ltd.) 0.009 g is dissolved in 85 g of tetrahydrofuran, a coating solution is prepared, coated on a CGL with a doctor blade, and a CTL having a film thickness of 20 μm after drying is laminated to obtain an electrophotographic photoreceptor. It was made. (A-1) and (B-2) were each dissolved in acetonitrile, and the reduction potential Ered was measured with respect to the reference electrode SCE,
(A-1) is -1.03V, (B-2) is -0.43V
It can be seen that (A-1) has a weaker electron affinity.

Example 6 An electrophotographic photoreceptor was prepared under the same conditions as in Example 5, except that the compound (A-2) represented by the following structural formula was used instead of (A-1). did.

[Chemical 15] When (A-2) was dissolved in acetonitrile and the reduction potential was measured, it was -0.90 V (vs SCE).
(B-2) is -0.43 V, which shows that (A-2) has a weaker electron affinity.

Example 7 A doctor blade was formed on a polyester film under the same conditions as in Example 5, except that the compound (A-3) represented by the following structural formula was used instead of (A-1). CGL having a thickness of 0.5 μm after coating and drying was provided.

[Chemical 16] Next, in Example 5, except that (B-2) was replaced with the compound (B-3) having the structural formula in Example 2 described above,
Under the same conditions as above, a CTL having a film thickness of 20 μm after being coated on the CGL with a doctor blade and being dried was laminated to prepare an electrophotographic photoreceptor. When (A-3) and (B-3) were each dissolved in acetonitrile and the reduction potential Ered was measured with respect to the reference electrode SCE, (A-3) was −.
0.94V, (B-3) is -0.59V, and (A-
It can be seen that 3) has a weaker electron affinity.

Example 8 An electrophotographic photoreceptor was prepared under the same conditions as in Example 7, except that the compound (A-4) in Example 7 was replaced with the compound (A-4) represented by the structural formula shown below. did.

[Chemical 17] When (A-5) was dissolved in acetonitrile and the reduction potential was measured, it was -0.78 V (vs SCE).
It can be seen from Example 7 that the reduction potential of (B-2) is -0.59 V, and (A-4) has a weaker electron affinity.

Example 9 A doctor film was formed on a polyester film under the same conditions as in Example 5, except that the acceptor compound (A-1) was replaced with the compound (A-5) represented by the following structural formula. CGL having a thickness of 0.5 μm after coating with a blade and drying was provided.

[Chemical 18] Next, in Example 5, the electron transfer material (B-
The CTL solution was applied onto the CGL with a doctor blade under the same conditions as in Example 5, except that 2) was replaced with the compound (B-5) represented by the following structural formula, and the film thickness after drying was 20 μm. The above CTLs were laminated to prepare a photoconductor for electrophotography.

[Chemical 19] When (A-5) and (B-5) were dissolved in acetonitrile and the reduction potential Ered was measured with respect to the reference electrode SCE, (A-5) was -0.875 V, (B-
5) is -0.47V, and it can be seen that (A-5) has a weaker electron affinity.

Example 10 A doctor film was formed on a polyester film under the same conditions as in Example 9 except that the acceptor compound (A-5) in Example 9 was replaced with the compound (A-6) represented by the following structural formula. CGL having a thickness of 0.5 μm after coating with a blade and drying was provided.

[Chemical 20] Next, in Example 5, the electron transfer material (B-
2) is the compound of the structural formula (B-
C) under the same conditions as in Example 5, except that 5) was used.
The CTL liquid was applied onto the GL with a doctor blade, and the dried CTL having a film thickness of 20 μm was laminated to prepare an electrophotographic photoreceptor. (A-6) is dissolved in acetonitrile,
When the reduction potential was measured, it was -0.885 V (vs S
CE). The reduction potential of the electron transfer material (B-5) used for CTL was −0.47 V, and (A−
It can be seen that 6) has a weaker electron affinity.

Example 11 A doctor film was formed on a polyester film under the same conditions as in Example 5, except that the acceptor compound (A-1) was replaced with the compound (A-7) represented by the following structural formula. C coated with a blade and having a thickness of 0.5 μm after drying
GL was provided.

[Chemical 21] Next, in Example 5, under the same conditions as in Example 5, except that the compound (B-4) having the structural formula shown in Example 4 was used instead of the electron transfer material (B-2) used in CTL. A CTL solution was applied onto the CGL with a doctor blade, and CTL having a film thickness of 20 μm after drying was laminated to produce an electrophotographic photoreceptor. When (A-7) and (B-4) were each dissolved in acetonitrile and the reduction potential Ered was measured with respect to the reference electrode SCE, (A-7) was-.
0.95V, (B-4) is -0.55V, (A-
It can be seen that 7) has a weaker electron affinity.

Example 12 Example 12 was repeated except that the acceptor compound (A-1) was replaced with the compound (A-8) represented by the following structural formula.
An electrophotographic photosensitive member was produced in the same manner as in Example 11.

[Chemical formula 22] When (A-8) was dissolved in acetonitrile and the reduction potential was measured, it was -1.05 V (vs SCE).
The reduction potential of the electron transfer material (B-4) used for CTL was -0.55 V, and it was found that (A-8) had a weaker electron affinity.

Example 13 Electrophotographic sensitization under the same conditions as in Example 5 except that the acceptor compound (A-1) in Example 5 was replaced with the compound (A-9) represented by the following structural formula. The body was made.

[Chemical formula 23] (A-9) is dissolved in acetonitrile to reduce the reduction potential Ere.
When d was measured with respect to the reference electrode SCE, it was -0.9.
It was 25V. The reduction potential of the electron transfer material (B-2) used for CTL was -0.43V, and (A-
It can be seen that 9) has a weaker electron affinity.

Example 14 Under the same conditions as in Example 13 except that the acceptor compound (A-9) in Example 13 was replaced with the compound (A-10) represented by the following structural formula, a photosensitive material for electrophotography was obtained. Created the body.

[Chemical formula 24] (A-10) is dissolved in acetonitrile and reduction potential Er
ed was measured with respect to the reference electrode SCE, and it was −0.
It was 87V. The reduction potential of the electron transfer material (B-2) used for CTL was −0.43V, and (A-1
It can be seen that 0) has a weaker electron affinity.

Example 15 Example 15 was repeated except that the acceptor compound (A-1) was replaced with the compound (A-11) represented by the following structural formula.
The polyester film was coated with a doctor blade under the same conditions as in Example 5, and the film thickness after drying was 0.5 μm.
CGL was installed.

[Chemical 25] Next, in Example 5, the electron transfer material (B-
2) is a compound of the structural formula (B-
C) under the same conditions as in Example 5, except that 5) was used.
The CTL liquid was applied onto the GL with a doctor blade, and the dried CTL having a film thickness of 20 μm was laminated to prepare an electrophotographic photoreceptor. When (A-11) was dissolved in acetonitrile and the reduction potential Ered was measured with respect to the reference electrode SCE, it was -0.53V. The reduction potential of the electron transfer material (B-5) used for CTL was -0.47 V, and it was found that (A-11) had a weaker electron affinity.

Comparative Example 1 For electrophotography under the same conditions as in Example 1 except that butyral resin (Elex BLS; manufactured by Sekisui Chemical Co., Ltd.) was used in place of the polycarbonate Z as the binder of CGL. A photoconductor was prepared.

Comparative Example 2 For electrophotography under the same conditions as in Example 2 except that butyral resin (Elex BLS; manufactured by Sekisui Chemical Co., Ltd.) was used in place of the polycarbonate Z as the binder of CGL. A photoconductor was prepared.

Comparative Example 3 For electrophotography under the same conditions as in Example 3, except that butyral resin (Elex BLS; manufactured by Sekisui Chemical Co., Ltd.) was used instead of the polycarbonate Z in the binder of CGL. A photoconductor was prepared.

Comparative Example 4 For electrophotography under the same conditions as in Example 3, except that butyral resin (Elex BLS; manufactured by Sekisui Chemical Co., Ltd.) was used in place of the polycarbonate Z as the binder of CGL. A photoconductor was prepared.

Comparative Example 5 For electrophotography under the same conditions as in Example 5, except that 2,4,5,7-tetranitrofluorenone was used in place of the acceptor compound (A-1) in Example 5. A photoconductor was prepared. When 2,4,5,7-tetranitrofluorenone was dissolved in acetonitrile and the reduction potential was measured, it was -0.155 V (vs SCE). Note that C
The reduction potential of the electron transfer material (B-2) used for TL is −
It is 0.43 V, and it can be seen that 2,4,5,7-tetranitrofluorenone has a stronger electron affinity.

Comparative Example 6 For electrophotography under the same conditions as in Example 7 except that 2,4,5,7-tetranitrofluorenone was used in place of the acceptor compound (A-3) in Example 7. A photoconductor was prepared. The reduction potential of 2,4,5,7-tetranitrofluorenone is -0.155V (vs SCE), CT
The reduction potential of the electron transfer material (B-3) used for L was −0.
It is 59 V, and it can be seen that 2,4,5,7-tetranitrofluorenone has a stronger electron affinity.

Comparative Example 7 For electrophotography under the same conditions as in Example 9 except that 2,4,5,7-tetranitrofluorenone was used in place of the acceptor compound (A-5) in Example 9. A photoconductor was prepared. The reduction potential of 2,4,5,7-tetranitrofluorenone is -0.155V (vs SCE), CT
The reduction potential of the electron transfer material (B-5) used for L was −0.
It is 47 V, and it can be seen that 2,4,5,7-tetranitrofluorenone has a stronger electron affinity.

Comparative Example 8 For electrophotography under the same conditions as in Example 9 except that 2,4,5,7-tetranitrofluorenone was used in place of the acceptor compound (A-5) in Example 9. A photoconductor was prepared. The reduction potential of 2,4,5,7-tetranitrofluorenone is -0.155V (vs SCE), CT
The reduction potential of the electron transfer material (B-4) used for L was −0.
It is 55 V, and it can be seen that 2,4,5,7-tetranitrofluorenone has a stronger electron affinity. The electrophotographic photoconductors of Examples and Comparative Examples thus produced were charged by applying +6 kV corona discharge for 20 seconds using an electrostatic copying paper tester (SP-428) manufactured by Kawaguchi Electric Co., Ltd. Surface potential Vs (V), the surface potential Vo (V) after dark decay for 20 seconds, and the exposure amount 1/2, the light required for the surface potential to decay to 1/2 after irradiation with 20 lux tungsten light. The surface potential V ₂₀ (V) after 30 seconds of irradiation was measured and the electrophotographic characteristics were evaluated. The results of the examples are shown in Table 4 (1).
Table 4 (2) shows the results of the comparative example.

[0038]

[Table 4 (1)]

[0039]

[Table 4 (2)]

[0040]

The positive charging type forward layer photoreceptor of the present invention is CGL,
By using at least the same binder as CTL, particularly polycarbonate Z, and by incorporating in CGL an acceptor compound having a larger reduction potential value (weak electron affinity) than the acceptor compound used in CTL. In addition, it is possible to obtain a laminated electrophotographic photosensitive member which is excellent in charging property and sensitivity, has excellent stability of electrostatic characteristics against repeated use for a long period of time, and has a small ozone generation amount, and which is used in a positive charging process.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a forward layer type laminated photoreceptor of the present invention. 1 conductive substrate 2 charge generation layer 3 charge transport layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masao Yoshikawa 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Kaoru Teramura 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Inside Ricoh Company (72) Inventor Yumi Ichikawa 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (10)

[Claims] 1. A charge generation layer (CGL) on a conductive substrate,
In a photoreceptor for electrophotography, which is formed by sequentially stacking a charge transport layer (CTL) containing an acceptor compound having an electron transport ability, in the CGL and the CTL, at least one kind of the same binder is added. An electrophotographic photosensitive member characterized by being contained. 2. The electrophotographic photoreceptor according to claim 1, wherein the same binder contained in CGL and CTL is polycarbonate Z. 3. The electrophotographic photoreceptor according to claim 1, wherein the CGL contains an acceptor compound having an electron transporting ability. 4. An acceptor compound is contained in CGL and CTL, and a reduction potential value of the acceptor compound contained in CGL is larger than a reduction potential value of the acceptor compound contained in CTL. The electrophotographic photosensitive member according to claim 1. 5. The electrophotographic photosensitive member according to claim 1, wherein the acceptor compound contained in CGL is an aromatic carbonyl compound represented by the general formula (I). [Chemical 1] [In the formula, R ₃ and R ₄ are each a hydrogen atom, a halogen atom,
Substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted heterocyclic group, alkoxycarbonyl group, aryloxycarbonyl group, N-
Alkylcarbamoyl group, alkylcarbonyl group, arylcarbonyl group, cyano group, nitro group, alkoxy group, aryloxy group, amino group, or the following formula (I-
a) represents a group represented by a), and n and m each represent an integer of 1 to 3. [Chemical 2] (However, A represents a hydrogen atom or an alkyl group, and at least one of B and D represents a substituted or unsubstituted phenyl group and the other represents a hydrogen atom.)]. 6. The photoreceptor for electrophotography according to claim 1, wherein the acceptor compound contained in CGL is a dicyanomethylene compound represented by the general formula (II). [Chemical 3] [In the formula, R ₃ and R ₄ are each a hydrogen atom, a halogen atom,
Substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted heterocyclic group, alkoxycarbonyl group, aryloxycarbonyl group, N-
Alkylcarbamoyl group, alkylcarbonyl group, arylcarbonyl group, cyano group, nitro group, alkoxy group, aryloxy group, amino group, or the following formula (II
-A), wherein n and m are 1 to 3 respectively.
Indicates an integer. [Chemical 4] (However, A represents a hydrogen atom or an alkyl group, and at least one of B and D represents a substituted or unsubstituted phenyl group and the other represents a hydrogen atom.)]. 7. An acceptor compound to be contained in CGL
The product is an α-cyanostilbe represented by the general formula (III).
2. An electron according to claim 1, which is a compound
Photoreceptor for photography. [Chemical 5] (In the formula, R₁, R₂Is a substituted or unsubstituted phenyl group,
Substituted or unsubstituted aryl group, substituted or unsubstituted
Polycyclic aromatic groups, or substituted or unsubstituted heterocycles
Represents a group. ) 8. The electrophotographic photoreceptor according to claim 1, wherein the acceptor compound contained in CGL is an oxazole compound represented by the general formula (IV). [Chemical 6] (In the formula, Ar ₁ and Ar ₂ represent a substituted or unsubstituted aromatic hydrocarbon group.) 9. The photoreceptor for electrophotography according to claim 1, wherein the acceptor compound contained in CGL is a vinylidene compound represented by the general formula (V). [Chemical 7] (In the formula, Ar ₁ and Ar ₂ represent a substituted or unsubstituted aromatic hydrocarbon group, and X represents a cyano group or an alkoxycarbonyl group.) 10. The electrophotographic photoreceptor according to claim 1, wherein the acceptor compound contained in CGL is a quinone compound represented by the general formula (VI). [Chemical 8] (In the formula, R ₁ is a hydrogen atom, a halogen atom, an alkyl group,
A substituted or unsubstituted phenyl group, R ₂ is a hydrogen atom, a halogen atom, an alkoxycarbonyl group, an N-alkylcarbamoyl group, a cyano group or a nitro group, and n is 1 to 3
Indicates an integer. )