JP3281968B2 - Negatively charged single-layer type electrophotographic photoreceptor - Google Patents

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 particularly to a negative charge type electrophotographic photoreceptor 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 photosensitive member.

[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, and a facsimile, an organic photosensitive member having a large degree of freedom in functional design has been used.
Organic photoreceptors include a charge generation layer (CGL) and a charge transport layer (C
And a single-layer photoconductor in which a charge generating substance is dispersed in a medium of a charge transporting substance. Laminated photoreceptors are the mainstream of organic photoreceptors that have been put to practical use. However, since the number of times of application of the photosensitive layer is three or more, productivity is poor, and a good image is obtained while maintaining a balance between sensitivity and durability. For this purpose, it is necessary to control the thickness of the CGL in the submicron range, which increases the cost. Further, when directly coated on a conductive substrate, the CGL is easily affected by irregularities of the substrate, which causes image defects. There is a disadvantage that. Thus, single-layer photoconductor dispersed in a binder resin and a charge transport material and charge generating material in the same layer has been proposed (JP 47-30330, JP-54-1633 JP ). However, since most of these are positively charged photoreceptors, the devices used for conventional 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-mentioned 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 of the present invention is to provide a charged single-layer type electrophotographic photosensitive member.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, provided a single-layer organic photoconductor on a conductive substrate directly or via an undercoat layer. , the photosensitive layer, at least a charge generating material, the following one
A hole transport material comprising a compound having a specific structure represented by the general formula (VI) , and the following general formulas (I), (II) and (II)
Compounds of specific structures represented by I), (IV) and (V)
Electron-transporting material comprising a compound selected from among the objects are dispersed in the binder, the ratio of the electron transporting material and the hole transport material 3: 2 to 50: 1 (weight ratio) It has been found that the object can be achieved by the negatively charged laminated photoreceptor characterized in that there is a certain characteristic. (1) A diphenoquinone-based compound represented by the following general formula (I)

Embedded image (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-based compounds

Embedded image (Wherein X and Y are a cyano group or an alkoxy group, A, B and W each consist of an acyl group, an alkoxycarbonyl group, a nitro group, an alkylaminocarbonyl group and derivatives thereof, and m is an integer of 0 to 2. Wherein n is an integer of 0 or 1.) (3) N-trinitrofluorenylidene-aniline derivative represented by the following general formula (III)

Embedded image (In the formula, R represents an alkyl group or a trifluoromethyl group.) (4) A naphthalenedicarbonimide compound represented by the following general formula (IV)

Embedded image (Wherein R is an alkyl group or an aralkyl group, R ′,
R '' is an alkylene group which may be the same or different,
Rc represents a cycloalkylene group or an arylene group.
A ₁ and A ₂ represent a hydrogen atom, an alkyl group, a nitro group, a cyano group, a carboxylic acid ester or a halogen atom which may be the same or different. k, m, and n are the same or different and are integers of 0 or 1, and all of k, m, and n do not become 0. (5) A naphthalenetetracarboxylic diimide compound represented by the following general formula (V).

Embedded image (Wherein R is an alkyl group or an aralkyl group, R ′,
R '' is an alkylene group which may be the same or different,
Rc represents a cycloalkylene group or an arylene group.
A ₁ and A ₂ represent a hydrogen atom, an alkyl group, a nitro group, a cyano group, a carboxylic acid ester or a halogen atom which may be the same or different. k, m, and n are the same or different and are integers of 0 or 1, and all of k, m, and n do not become 0. (6) a compound represented by the following general formula (VI)

Embedded image (Wherein, R ₁ and R _{2 each} 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 represent alkyl groups. Group, an aryl group or a heterocyclic group.)

In the present invention, since the charging system is negative, the movement of electrons generated by light irradiation in the absorption wavelength region in the charge generating material plays an important role. Since electron transfer is mainly performed by using an electron transporting substance, it is necessary to use an electron transporting substance having a large electron transfer. However, a conventionally known electron transporting material is disclosed in Japanese Patent Application Laid-Open No. 61-233750.
In the anthraquinodimethane derivative shown in Japanese Patent Publication No.
The electron mobility was not sufficient.

As apparent from the comparative examples described below, the object of the present invention cannot be achieved even if anthraquinodimethane is used as the electron transporting material. 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 formulas (I) to (V) used in the present invention are shown in Table 1.
Table 6 shows specific examples of the hole transporting substance represented by the general formula (VI). The following electron transport materials are considered to be able to achieve the object of the present invention because the electron transfer is relatively large as compared with the anthraquinodimethane derivative of Comparative Example described later. When the ratio is less than 3: 2 to 50: 1 (weight ratio) with respect to the amount of the transporting substance, the chargeability is poor, the sensitivity is low, and the object of the present invention can be achieved, as is apparent from the comparative examples described later. 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)]

FIG. 1 shows a typical configuration of the negatively charged single-layer type electrophotographic photoreceptor of the present invention. 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 dispersed in a binder resin in a molecular state. In addition, 1 is a conductive substrate. The role of the binder in the photoreceptor plays a role not only in the good dispersion of the charge generating substance and the molecular dispersion of the electron transfer substance and the hole transfer substance, but also in the mechanical strength of the photoreceptor required in the copying process. I have. Therefore, when the composition of the binder is low, these various properties are impaired. Therefore, the composition of the binder cannot be lowered unnecessarily. Usually, the binder is designed so as to account for about 50 wt% in the photosensitive layer configuration.

Examples of the binder usable in the present invention include polyethylene, polypropylene, acrylic resin, methacrylic resin, polystyrene, vinyl chloride resin, vinyl acetate resin, polycarbonate resin, polyester resin, phenoxy resin, polyurethane resin, and vinylidene fluoride. Resin, silicone resin, melamine resin, alkyd resin,
Addition polymerization type resin such as phenolic resin, polyaddition type resin,
Polycondensation resins and copolymer resins containing two or more of these repeating units, for example, vinyl chloride-vinyl acetate resin copolymers, vinylidene fluoride-trifluoroethylene copolymers, and the like can be given. These compositions preferably have a content of 30 to 70% by weight. In the photoreceptor of the present invention, an undercoat layer can be provided between the photosensitive layer and the conductive support for the purpose of improving the chargeability. As these materials, a polyamide resin, polyvinyl alcohol, casein, polyvinyl pyrrolidone, or the like can be used in addition to the above-mentioned binder. 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 them, the central skeleton of the azo pigment is preferably an electron donating group such as a carbazole group, a styryl group, a diphenylamine group, and a triphenylamine group.

The conductive support used in the present invention may be a metal plate such as aluminum, nickel, copper or stainless steel, a metal drum or 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 thickness of the photosensitive layer of the present invention is 5 to 100 μm, preferably 10 to 40 μm.
About m is appropriate. When the thickness is less than 5 μm, the chargeability decreases, and when the thickness is more than 100 μm, the sensitivity decreases. The photoreceptor of the present invention is prepared by dissolving a predetermined material in an organic solvent, or applying a coating solution dispersed by a ball mill, ultrasonic wave, a homomixer or the like on a conductive support by dipping, blade, spray, or the like. You.

[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 thereto.

Example 1 Ball milling was performed together 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 at 2 wt% in tetrahydrofuran). Thereafter, this liquid was charged with the composition of 2% by weight of the charge generating substance, the composition of 50% by weight of the Pc-Z, and the charge transporting substance of No. 1 in Table 1. A-1 is 30wt%, F-
20 wt% Pc- so that the composition becomes 18 wt%.
A Z solution, an electron transport material, a hole transport material, and tetrahydrofuran were added to prepare a photoconductor coating solution. This coating solution is applied on an aluminum substrate, dried by heating, and
Was prepared.

Embedded image

Examples 2 and 3, 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 substance and the hole transporting substance were changed as shown in Table 7. .

Example 4 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 and 6, 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 substance and the hole transporting substance were changed as shown in Table 7. .

Example 7 As an electron transporting substance, 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 substance and the hole transporting substance were changed as shown in Table 7. .

Example 10 As an electron transporting substance, No. 4 in Tables 4 to (1). 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 and 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 substance and the hole transporting substance were changed as shown in Table 7. .

Example 13 As an electron transport material, No. 5 in Tables 5- (1) A single-layer 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 A single-layer type photoreceptor was prepared in the same manner as in Example 13 except that the composition amounts of the electron transporting substance and the hole transporting substance 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 an anthraquinodimethane derivative represented by the following structural formula (2) was used as an electron transporting substance.

Embedded image

Comparative Examples 7 to 9 Single-layer photosensitive members were prepared in the same manner as in Example 6, except that the composition amounts of the electron transporting substance and the hole transporting substance were changed as shown in Table 7. The electrophotographic photosensitive members prepared according to Examples 1 to 15 and Comparative Examples 1 to 9 were evaluated using a copy paper test device (SP-428) manufactured by Kawaguchi Electric Co., Ltd.

In the evaluation, the surface was charged by a corona discharge of -6 KV first, and the surface potential Vo after standing for 20 seconds was determined. continue,
Exposure (tungsten lamp) was performed so that the surface illuminance became 20 lux, and the exposure amount (E1 / 2) required for the surface potential to attenuate to １ ／ was measured. Table 7 shows the results.

[0034]

[Table 7]

[0035]

As is apparent from the above results, the ratio of the electron transporting material to the hole transporting material dispersed in the binder resin in the negatively charged single-layer type electrophotographic photoreceptor of the present invention is 3: 2
By using an electron transporting material having a specific structure and a hole transporting material having a specific structure, a photoreceptor having good chargeability and high sensitivity can be obtained.

[Brief description of the drawings]

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

[Explanation of symbols]

Reference Signs List 1 conductive substrate 2 charge generating substance 3 matrix in which electron transporting substance and hole transporting substance are dispersed in a binder resin in a molecular state.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akio Kojima 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP 5-150479 (JP, A) JP JP-A-5-150481 (JP, A) JP-A-5-150491 (JP, A) JP-A-4-295853 (JP, A) JP-A-3-144573 (JP, A) JP-A-60-69657 (JP, A A) JP-A-5-279582 (JP, A) JP-A-5-19511 (JP, A) JP-A-5-19505 (JP, A) JP-A-5-142812 (JP, A) JP-A-5 JP-A-127405 (JP, A) JP-A-63-188149 (JP, A) JP-A-59-216853 (JP, A) JP-A-5-72751 (JP, A) (58) Fields investigated (Int. . ^7, DB name) G03G 5/00

Claims (1)

(57) [Claims] 1. A least a charge generating material on a conductive substrate, the single-layer type electrophotographic photoreceptor and an electron transport material and hole transport material is contained in the same layer, the electron transporting
A diphenoquinone-based substance represented by the following general formula (I)
Fluorenone compound represented by the following general formula (II)
Compound, N-trinitro represented by the following general formula (III)
A fluorenylidene-aniline derivative represented by the following general formula (I
V) a fluorenone-based compound represented by the following general formula:
Naphthalenetetracarboxylic diimide represented by (V)
One compound selected from the group consisting of compounds,
The hole transport material is a compound represented by the following general formula (VI)
There, and the ratio of the electron transporting material and hole transporting material 3: 2 to 50: 1 negatively charged monolayer type electrophotographic photoreceptor, characterized in that the (weight ratio). Embedded image (Wherein, 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). (Wherein X and Y are a cyano group or an alkoxy group, A, B and W each consist of an acyl group, an alkoxycarbonyl group, a nitro group, an alkylaminocarbonyl group and derivatives thereof, and m is an integer of 0 to 2. And n is an integer of 0 or 1.) (In the formula, R represents an alkyl group or a trifluoromethyl group.) (Wherein R is an alkyl group or an aralkyl group, R ′,
R '' is an alkylene group which may be the same or different,
Rc represents a cycloalkylene group or an arylene group.
A ₁ and A ₂ represent a hydrogen atom, an alkyl group, a nitro group, a cyano group, a carboxylic acid ester or a halogen atom which may be the same or different. k, m, and n are the same or different and are integers of 0 or 1, and all of k, m, and n do not become 0. ) (Wherein R is an alkyl group or an aralkyl group, R ′,
R '' is an alkylene group which may be the same or different,
Rc represents a cycloalkylene group or an arylene group.
A ₁ and A ₂ represent a hydrogen atom, an alkyl group, a nitro group, a cyano group, a carboxylic acid ester or a halogen atom which may be the same or different. k, m, and n are the same or different and are integers of 0 or 1, and all of k, m, and n do not become 0. ) (Wherein, R ₁ and R _{2 each} 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 represent alkyl groups. Group, an aryl group or a heterocyclic group.)