JPH07191474A - Negative charge monolayer electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain such a negative charge monolayer electrophotographic photoreceptor that the coating process is simple and an image forming device used for a conventional negative laminated photoreceptor can be used. CONSTITUTION:This monolayer electrophotographic photoreceptor contains at least a charge generating material 2, electron transfer material and hole transfer material in one layer on a conductive base body 1. The weight ratio of the electron transfer material to the hole transfer material is 3:2 to 50:1. In this method, the electron transfer material is preferably a diphenoquinone compd. expressed by the formula. In the formula, R1-R6 are hydrogen atoms, alkyl groups or fluorine-substd. alkyl groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more specifically, to a negatively charged type containing a charge generating substance, an electron transporting substance having a specific structure and a hole transporting substance having a specific structure in the same layer. The present invention relates to an electrophotographic photoreceptor.

[0002]

2. Description of the Related Art In recent years, as an electrophotographic photosensitive member in an image forming apparatus such as a copying machine, a printer or a facsimile, an organic photosensitive member having a large degree of freedom in functional design has been used.
The organic photoconductor has a charge generation layer (CGL) and a charge transport layer (C
There is known a function-separated type laminated photoconductor in which TL) is laminated, and a single-layer photoconductor in which a charge generation substance is dispersed in a medium of a charge transport substance. Laminated photoreceptors are the mainstream of practically used organic photoreceptors, but productivity is poor because the number of times the photosensitive layer is applied is three or more, and a good image is obtained with a balance between sensitivity and durability. In order to sag, it is necessary to control the film thickness of CGL in the range of submicron, resulting in an increase in cost. Further, when directly coated on a conductive substrate, it is easily affected by unevenness of the substrate, which causes image defects. There is a drawback that. Therefore, a single-layer photoreceptor in which a charge generating substance and a binder resin are dispersed in the same layer has been proposed (JP-A 47-30330 and JP-A 54-1633). However, since these members are positively charged photoreceptors, the conventional apparatus used for negatively charged laminated photoreceptors cannot be used as they are, and negatively charged laminated photoreceptors have not yet been put to practical use.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, to simplify the coating process, and to use the image forming apparatus used in the conventional negatively charged laminated photoreceptor as it is. An object is to provide a charged single-layer type electrophotographic photoreceptor.

[0004]

DISCLOSURE OF THE INVENTION As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that a single-layer organic photoreceptor is provided on a conductive substrate directly or through an undercoat layer. In the photosensitive layer, at least a charge generating substance, a hole transporting substance and an electron transporting substance are dispersed in a binder, and the ratio of the electron transporting substance to the hole transporting substance is 3: 2 to 50: 1 (weight ratio).
It has been found that the object can be achieved by a negatively charged laminated photoreceptor which is characterized by At this time, the compounds represented by the following general formulas (I) to (V) are desirable as the electron transporting substance, and the compounds represented by (VI) are desirable as the hole transporting substance. (1) A diphenoquinone compound represented by the following general formula (I)

[Chemical 1] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ represent the same or different hydrogen atoms, alkyl groups or fluorine-substituted alkyl groups.) (2) The following general formula (II ) Fluorenone compounds

[Chemical 2] (In the formula, X and Y are cyano groups or alkoxy groups, A, B and W are acyl groups, alkoxycarbonyl groups, nitro groups, alkylaminocarbonyl groups and derivatives thereof, and m is an integer of 0 to 2. And n is an integer of 0 or 1.) (3) N-trinitrofluorenylidene-aniline derivative represented by the following general formula (III)

[Chemical 3] (In the formula, R represents an alkyl group or a trifluoromethyl group.) (4) Naphthalenedicarbonimide compound represented by the following general formula (IV)

[Chemical 4] (In the formula, R is an alkyl group or an aralkyl group, R ′,
R '' are the same or different alkylene groups,
Rc represents a cycloalkylene group or an arylene group.
A ₁ and A ₂ represent the same or different hydrogen atom, alkyl group, nitro group, cyano group, carboxylic acid ester or halogen atom. k, m and n are the same or different integers of 0 or 1, and k, m and n are not all 0. (5) A naphthalenetetracarboxylic acid diimide compound represented by the following general formula (V).

[Chemical 5] (In the formula, R is an alkyl group or an aralkyl group, R ′,
R '' are the same or different alkylene groups,
Rc represents a cycloalkylene group or an arylene group.
A ₁ and A ₂ represent the same or different hydrogen atom, alkyl group, nitro group, cyano group, carboxylic acid ester or halogen atom. k, m and n are the same or different integers of 0 or 1, and k, m and n are not all 0. ) (6) Compound represented by the following general formula (VI)

[Chemical 6] (In the formula, R ₁ and R ₂ represent a hydrogen atom, an alkyl group or an aryl group, and may form a ring. Ar ₁ represents an arylene group or a heterocyclic group, and Ar ₂ and Ar ₃ are alkyl. Represents a group, an aryl group or a heterocyclic group.)

In the present invention, since the charging method is negative, the movement of the electrons generated by light irradiation in the absorption wavelength region in the charge generating substance plays an important role. Since electron transfer is mainly performed by an electron transport material, it is necessary to use an electron transport material having a large electron transfer. However, a conventionally known electron-transporting substance is disclosed in JP-A-61-233750.
In the anthraquinodimethane derivative shown in the publication,
Its electron mobility was not sufficient.

As the electron-transporting substance, it is impossible to achieve the object of the present invention even if anthraquinodimethane is used as the electron-transporting substance, as will be apparent from the comparative example described later. That is,
The object of the present invention is achieved by using an electron transport material having a specific structure. Hereinafter, specific examples of the electron transport materials represented by the general formulas (I) to (VI) that are preferably used in the present invention are shown in Tables 1 to 6. The electron-transporting substance below has a relatively large electron transfer as compared with the anthraquinodimethane derivative of the comparative example described below, and thus it is considered that the object of the present invention can be achieved. When the ratio is less than 3: 2 to 50: 1 (weight ratio) with respect to the amount of the transport material, the chargeability is poor and the sensitivity is low as will be apparent from the comparative examples described below, and the object of the present invention can be achieved. Can not.

[0007]

[Table 1]

[0008]

[Table 2]

[0009]

[Table 3]

[0010]

[Table 4- (1)]

[0011]

[Table 4- (2)]

[0012]

[Table 5- (1)]

[0013]

[Table 5- (2)]

[0014]

[Table 6- (1)]

[0015]

[Table 6- (2)]

[0016]

[Table 6- (3)]

A typical constitution of the negatively charged single-layer type electrophotographic photosensitive member of the present invention is shown in FIG. The photosensitive layer is composed of a charge generating substance 2 and a matrix 3 in which an electron transporting substance and a hole transporting substance are molecularly dispersed in a binder resin. In addition, 1 is a conductive substrate. The role of the binder in the photoconductor is not only good dispersion of the charge generating substance and molecular dispersion of the electron transfer substance and hole transfer substance, but also the mechanical strength of the photoconductor required in the copying process. There is. Therefore, when the composition of the binder is low, these various properties are impaired. Therefore, the composition of the binder cannot be lowered unreasonably. Usually, the binder is designed to occupy about 50 wt% in the photosensitive layer structure.

The binder which can be used in the present invention is polyethylene, polypropylene, acrylic resin, methacrylic resin, polystyrene, vinyl chloride resin, vinyl acetate resin, polycarbonate resin, polyester resin, phenoxy resin, polyurethane resin, vinylidene fluoride. Resin, silicone resin, melamine resin, alkyd resin,
Addition polymerization type resin such as phenol resin, polyaddition type resin,
Examples thereof include polycondensation type resins and copolymer resins containing two or more of these repeating units, such as vinyl chloride-vinyl acetate resin copolymers and vinylidene fluoride-trifluoroethylene copolymers. The composition of these is preferably 30 to 70 wt%. In the photoreceptor of the present invention, an undercoat layer may be provided between the photosensitive layer and the conductive support for the purpose of improving the charging property. As these materials, in addition to the above-mentioned binder, polyamide resin, polyvinyl alcohol, casein, polyvinylpyrrolidone, etc. can be used. Examples of the charge generating substance that can be used in the present invention include bisazo pigments, trisazo pigments, phthalocyanine pigments, perylene pigments, quinacridone pigments, indigo pigments, and polycyclic quinone pigments. Among these, the central skeleton of the azo pigment is preferably an electron donating group such as a carbazole group, a styryl group, a diphenylamine group, or a triphenylamine group.

As the conductive support used in the present invention, a metal plate such as aluminum, nickel, copper or stainless steel, a metal drum or a metal foil, a plastic film coated with a thin film of aluminum, tin oxide or copper iodide. Alternatively, glass or the like can be used. The film thickness of the photosensitive layer of the present invention is 5 to 100 μm, preferably 10 to 40 μm.
m is suitable. If it is thinner than 5 μm, the charging property is lowered, and if it is thicker than 100 μm, the sensitivity is lowered. The photoreceptor of the present invention is prepared by dissolving a predetermined material in an organic solvent, or coating a coating solution dispersed by a ball mill, ultrasonic wave, homomixer or the like on a conductive support by dipping, blade, spraying or the like. It

[0020]

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

Example 1 Ball milling was performed with 0.25 g of X-type metal-free phthalocyanine and 6.25 g of a polycarbonate Z (Pc-Z) solution represented by the following structural formula (1) (dissolved in tetrahydrofuran at 2 wt%). Then, the composition of the charge generating substance was 2 wt%, the composition of Pc-Z was 50 wt%, and the charge transporting substance of No. 1 in Table 1 was added to this liquid. A-1 is 30 wt%, F-
20 composition is 18 wt% so that 10 wt% Pc-
A Z solution, an electron transporting substance, a hole transporting substance, and tetrahydrofuran were added to prepare a coating liquid for the photoreceptor. This coating solution is coated on an aluminum substrate and dried by heating to about 20 μm.
A single-layer type photoconductor was prepared.

[Chemical 7]

Examples 2, 3 and Comparative Example 1 A single layer type photoreceptor was prepared in the same manner as in Example 1 except that the composition amounts of the electron transporting material and the hole transporting material were changed as shown in Table 7. .

Example 4 No. 2 in Table 2 was selected as the electron transporting substance. A single-layer type photoreceptor was prepared in the same manner as in Example 1 except that B-1 was used.

Examples 5, 6 and Comparative Example 2 A single layer type photoreceptor was prepared in the same manner as in Example 4 except that the composition amounts of the electron transporting material and the hole transporting material were changed as shown in Table 7. .

Example 7 As the electron transporting substance, No. 3 in Table 3 was used. A single-layer type photoreceptor was prepared in the same manner as in Example 1 except that C-4 was used.

Examples 8 and 9, Comparative Example 3 A single-layer type photoreceptor was prepared in the same manner as in Example 7 except that the composition amounts of the electron transporting material and the hole transporting material were changed as shown in Table 7. .

Example 10 Nos. 4 to (1) shown in Tables 4 to 1 as electron transporting substances A single-layer type photoreceptor was prepared in the same manner as in Example 1 except that D-8 was used.

Examples 11 and 12, Comparative Example 4 A single-layer type photoreceptor was prepared in the same manner as in Example 10 except that the composition amounts of the electron transporting material and the hole transporting material were changed as shown in Table 7. .

Example 13 As the electron-transporting substance, Nos. A single-layer type photoreceptor was prepared in the same manner as in Example 1 except that E-11 was used.

Examples 14 and 15 and Comparative Example 5 Single layer type photoreceptors were prepared in the same manner as in Example 13 except that the composition amounts of the electron transporting material and the hole transporting material were changed as shown in Table 7. .

Comparative Example 6 A single-layer type photoreceptor was prepared in the same manner as in Example 1 except that the anthraquinodimethane derivative represented by the following structural formula (2) was used as the electron transport material.

[Chemical 8]

Comparative Examples 7 to 9 Single layer type photoreceptors were prepared in the same manner as in Example 6 except that the composition amounts of the electron transporting material and the hole transporting material were changed as shown in Table 7. The electrophotographic photoreceptors produced according to Examples 1 to 15 and Comparative Examples 1 to 9 were evaluated using a copying paper test apparatus (SP-428) manufactured by Kawaguchi Denki KK.

The evaluation was carried out by first charging the surface with a corona discharge of -6 KV and determining the surface potential Vo after standing for 20 seconds. continue,
The exposure (tungsten lamp) was performed so that the surface illuminance was 20 lux, and the exposure amount (E1 / 2) required for the surface potential to be attenuated to 1/2 was measured. The results are shown in Table 7.

[0034]

[Table 7]

[0035]

As is apparent from the above results, in the negatively charged single-layer type electrophotographic photoreceptor of the present invention, the ratio of the electron transporting substance and the hole transporting substance dispersed in the binder resin is 3: Two
By using an electron-transporting substance having a specific structure and a hole-transporting substance having a specific structure at a ratio of ˜50: 1 (weight ratio), it is possible to obtain a photoreceptor having good charging property and high sensitivity.

[Brief description of drawings]

FIG. 1 is a diagram showing a typical layer structure of a negatively charged single-layer type electrophotographic photosensitive member.

[Explanation of symbols]

1 Conductive Substrate 2 Charge Generating Material 3 Binder A matrix in which an electron transporting material and a hole transporting material are molecularly dispersed in a resin.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Kojima 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (7)

[Claims] 1. A single-layer type electrophotographic photoreceptor in which at least a charge-generating substance, a charge-generating substance, and a hole-transporting substance are contained in the same layer on a conductive substrate. A negatively charged single-layer type electrophotographic photosensitive member characterized in that the ratio with the transport substance is 3: 2 to 50: 1 (weight ratio). 2. The electron transporting material is represented by the following general formula (I):
The negatively charged single-layer type electrophotographic photoconductor according to claim 1, which is a diphenoquinone compound represented by [Chemical 1] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ represent the same or different hydrogen atoms, alkyl groups or fluorine-substituted alkyl groups.) 3. The electron transporting material is represented by the following general formula (II):
The negatively charged single-layer type electrophotographic photosensitive member according to claim 1, which is a fluorenone-based compound represented by: [Chemical 2] (In the formula, X and Y are cyano groups or alkoxy groups, A, B and W are acyl groups, alkoxycarbonyl groups, nitro groups, alkylaminocarbonyl groups and derivatives thereof, and m is an integer of 0 to 2. And n is an integer of 0 or 1.) 4. The electron transporting material is represented by the following general formula (II
The negatively charged single-layer type electrophotographic photoreceptor according to claim 1, which is an N-trinitrofluorenylidene-aniline derivative represented by I). [Chemical 3] (In the formula, R represents an alkyl group or a trifluoromethyl group.) 5. The electron transporting material is represented by the following general formula (IV):
The negatively charged single-layer type electrophotographic photosensitive member according to claim 1, which is a fluorenone-based compound represented by: [Chemical 4] (In the formula, R is an alkyl group or an aralkyl group, R ′,
R '' are the same or different alkylene groups,
Rc represents a cycloalkylene group or an arylene group.
A ₁ and A ₂ represent the same or different hydrogen atom, alkyl group, nitro group, cyano group, carboxylic acid ester or halogen atom. k, m and n are the same or different integers of 0 or 1, and k, m and n are not all 0. ) 6. The electron transporting material is represented by the following general formula (V):
The negatively-charged single-layer type electrophotographic photoreceptor according to claim 1, which is a naphthalenetetracarboxylic acid diimide compound represented by: [Chemical 5] (In the formula, R is an alkyl group or an aralkyl group, R ′,
R '' are the same or different alkylene groups,
Rc represents a cycloalkylene group or an arylene group.
A ₁ and A ₂ represent the same or different hydrogen atom, alkyl group, nitro group, cyano group, carboxylic acid ester or halogen atom. k, m and n are the same or different integers of 0 or 1, and k, m and n are not all 0. ) 7. The hole transport material is represented by the following general formula (VI):
The negatively charged single-layer type electrophotographic photoconductor according to claim 1, which is a compound represented by: [Chemical 6] (In the formula, R ₁ and R ₂ represent a hydrogen atom, an alkyl group or an aryl group, and may form a ring. Ar ₁ represents an arylene group or a heterocyclic group, and Ar ₂ and Ar ₃ are alkyl. Represents a group, an aryl group or a heterocyclic group.)