JPH10153869A - Electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a photoconductor excellent in both initial characteristics and durability against deterioration in mechanical and electrical characteristics. SOLUTION: In an electrophotographic photosensitive member having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, at least the following general formula (1) is used as the charge generating substance.
And a resin having a unit having a structure represented by the following general formula (2) as a binder resin. A carbon atom to which the azo group is bonded, represents a divalent group which is a SP ² type carbon atoms forming the double bond, R represents an alkyl group which may have a substituent. Y is a hydrogen atom,
Represents a halogen atom, an alkyl group or an alkoxy group. ) (R _1-10 each independently represents a hydrogen atom, an alkyl group, a halogen atom or an aryl group, and R ₅ and R ₆ may form a ring with each other.)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photosensitive member. More specifically, the present invention relates to an electrophotographic photoreceptor having a good image.

[0002]

2. Description of the Related Art Selenium,
Inorganic photoconductive substances such as cadmium sulfide and zinc oxide have been widely used. However, selenium and cadmium sulfide need to be recovered as poisons, selenium crystallizes by heat, and therefore has poor heat resistance, cadmium sulfide and zinc oxide have poor moisture resistance, and zinc oxide has no printing durability. Therefore, efforts have been made to develop new photoconductors.

[0003] On the other hand, studies have been made on the use of an organic photoconductive substance for a photosensitive layer of an electrophotographic photosensitive member, and some of them have been put to practical use. Organic photoconductive materials have advantages over inorganic ones, such as being lighter, easier to form films, easier to manufacture photoconductors, and capable of manufacturing transparent photoconductors depending on the type. Have. While having many advantages in this way,
Organic photoconductive materials have not been widely used as electrophotographic photoreceptors because of problems in sensitivity and durability.

[0004] Recently, a so-called laminated (separated function) type photoreceptor in which charge carrier generation and transfer functions are shared by different compounds is effective for increasing sensitivity, and thus has become the mainstream of development. Therefore, an organic photoconductor of this type has been put to practical use. Among them, an electrophotographic photoreceptor using a specific azo compound as a charge generating substance has high sensitivity and a wide spectral sensitivity in a white light region, and is practically used. On the other hand, various factors can be cited as main factors that determine the durability of the laminated photoreceptor. That is, there are mechanical deterioration such as abrasion and surface scratches caused by development with toner, friction with paper, friction with a cleaning member, and the like, and deterioration due to electrical characteristics due to active gas generated during corona discharge. .

[0005]

In recent years, photoconductors typified by laminated photoconductors have made great progress in terms of sensitivity and the like due to improvements in charge generation materials and the like. However, when such a photoreceptor is used in a copying machine or the like, satisfactory durability is often not obtained due to mechanical deterioration or deterioration in electrical characteristics.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on an electrophotographic photosensitive member having high sensitivity and excellent durability, and have found that a specific charge-generating substance and a specific binder resin are used to improve the sensitivity. It has been found that a photoreceptor excellent in both initial characteristics, such as deterioration in mechanical and electrical characteristics, can be obtained. That is, the gist of the present invention is to provide an electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, at least as a charge generating substance represented by the following general formula (1)
And an electrophotographic photoreceptor comprising a resin having a unit having a structure represented by the following general formula (2) as a binder resin.

[0007]

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A represents a divalent group in which the carbon atom to which the azo group is bonded is an SP ² type carbon atom forming a double bond, and R represents an alkyl group which may have a substituent. Represent. Y
Represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group. )

[0009]

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(R _1-10 are each independently a hydrogen atom,
R ₅ represents an alkyl group, a halogen atom or an aryl group;
And R ₆ may form a ring with each other. Where R _1-4 , R
Excluding homopolymers in which _7-10 is a hydrogen atom and R _5,6 is a methyl group. )

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The electrophotographic photoreceptor of the present invention has a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support. Examples of the conductive support include metal materials such as aluminum, stainless steel, copper, and nickel; insulating films such as paper and polyester films provided with a conductive layer such as aluminum, copper, palladium, tin oxide, and indium oxide on the surface; A support or the like is used.

A known barrier layer, which is usually used, may be provided between the conductive support and the photosensitive layer.
As the barrier layer, for example, an anodized aluminum film, aluminum oxide, an inorganic layer such as aluminum hydroxide, an organic layer such as polyvinyl alcohol, casein, polyacrylic acid, polyurethane, polyimide, polyamide, and nylon are used. A conductive fine powder such as carbon black, aluminum, copper, tin oxide, zinc oxide, and titanium oxide may be contained.

The layer structure of the photosensitive layer includes a charge generating substance,
A single layer type in which a charge transporting material is dispersed, a layered type in which a charge generation layer and a charge transporting layer are stacked in this order, and a layered type in which the charge transporting layer is stacked in the reverse order are known, and any of these layer configurations may be adopted. As the charge generating substance, an azo compound represented by the following general formula (1) is used.

[0014]

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In the above general formula (1),

[0016]

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Y represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, specifically, for example, a halogen atom such as a fluorine atom, a chlorine atom, an iodine atom; a methyl group, an ethyl group, an n-propyl group, an iso- Propyl group,
alkyl groups such as n-butyl group, iso-butyl group and n-hexyl group; methoxy group, ethoxy group, propoxy group,
Examples include an alkoxy group such as a butoxy group. Among them, a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, a methoxy group and the like are preferable.

In the general formula (1), A represents a divalent group in which the carbon atom to which the azo group is bonded is a carbon atom of the SP ² type forming a double bond, and specifically, is an aromatic group. A divalent group of a hydrocarbon ring or an aromatic heterocyclic ring, or a directly-bonded or condensed condensed ring thereof, or a linking group, an aromatic hydrocarbon ring, or an aliphatic hydrocarbon ring And a divalent group linked by a heterocyclic ring. A typical example is an aromatic hydrocarbon ring 2
Examples of the divalent group include divalent groups derived from benzene, naphthalene, anthracene, pyrene, fluorenone, anthraquinone, phenanthrene, biphenylene, triphenylene, perylene, and the like.Examples of the aromatic heterocyclic divalent group include carbazole, Acridine, acridone,
Examples include divalent groups derived from xanthone, phenazine, dibenzothiophene, dibenzofuran, benzimidazole, benzothiazole, and the like. Further, Table 1 below shows some specific examples of divalent groups derived from those in which divalent groups of these aromatic hydrocarbon rings or aromatic heterocycles are directly bonded or form a condensed ring.

[0019]

[Table 1]

Examples of the linking group include -O-, -S-,-
S-S-, -SO-, -SO_Two-, -SO_TwoNH-,-
CH _Two-, -NH-,

[0021]

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[0022] and so on.

Examples of the aromatic hydrocarbon ring, aliphatic hydrocarbon ring and heterocyclic ring include benzene, naphthalene, acenaphthene, anthracene, pyrene, fluorene, fluorenone, phenanthrene, naphthoquinone, anthraquinone, cyclohexane, cyclohexanone, piperazine, and the like.
Examples include pyrrole, furan, thiophene, oxazole, isoxazole, thiazole, pyrazole, pyrazoline, imidazole, imidazolidine, oxadiazole, thiadiazole, triazole, pyridine, indole, quinoline, carbazole, xanthene, xanthone, coumarin, and phenothiazine. A is obtained by combining these hydrocarbon rings or heterocyclic rings with the above-mentioned bonding groups. These bonding groups, hydrocarbon rings and heterocycles may have a substituent. Some of these specific examples are shown in Table 2 below.

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

In the general formula (1), R represents an alkyl group which may have a substituent. Among them, a linear or branched alkyl group having 3 to 8 carbon atoms which may have a substituent or a cycloalkyl group which may have a substituent is preferable.
Specifically, for example, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, neopentyl group, tert- Pentyl group, 1
-Methylbutyl group, 1-ethylpropyl group, n-hexyl group, iso-hexyl group, 1-methylpentyl group, 1
-Ethylbutyl group, 2-ethylbutyl group, 2-methylpentyl group, 3-methylpentyl group, n-heptyl group, i
so-heptyl group, 1-methylhexyl group, 1-propylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclobutylmethyl group, cyclopropylmethyl group, n-octyl group, iso- Examples thereof include an octyl group and a 2-ethylhexyl group.

Among them, iso-propyl, iso-butyl, iso-pentyl, iso-hexyl, 2-
Preferred are an ethylbutyl group, an n-pentyl group, an n-hexyl group, a cyclohexylmethyl group, a 2-ethylhexyl group and the like. As the charge transport substance, for example, a known compound such as a high molecular compound such as polyvinyl carbazole or polyvinyl pyrene or a low molecular compound such as an arylamine, benzidine, pyrazoline, oxazole, hydrazone, or stilbene derivative can be used. For the photosensitive layer, a binder resin having a unit having a structure represented by the following general formula (2) is used.

[0030]

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R _1-10 represents a hydrogen atom, a methyl group, an ethyl group,
It represents an alkyl group such as a propyl group, a halogen atom such as a chlorine atom or a bromine atom, or an aryl group such as a phenyl group or a naphthyl group, and R ₅ and R ₆ may mutually form a ring such as a cyclohexane ring. Of these, a hydrogen atom, a methyl group, a bromine atom, a phenyl group, or R ₅ and R ₆ preferably form a cyclohexane ring.

Provided that R _1-4 and R _7-10 are a hydrogen atom, R _5,6
Is a homopolymer in which is a methyl group. As the binder resin used for the photosensitive layer, a homopolymer composed of a unit represented by the general formula (2), a copolymer composed of a plurality of units represented by the general formula (2), and other units represented by the general formula (2) Any of copolymers with the unit represented by The other unit may be any unit capable of forming a copolymer with polycarbonate, but is preferably a unit represented by the following general formula (5) or (6).

[0033]

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R _11-18 represents a hydrogen atom, an alkyl group such as a methyl group, an ethyl group or a propyl group, a halogen atom such as a chlorine atom or a bromine atom, or an aryl group such as a phenyl group or a naphthyl group, and a hydrogen atom is preferable. .

[0035]

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R _19-26 represents a hydrogen atom, an alkyl group such as a methyl group, an ethyl group or a propyl group, a halogen atom such as a chlorine atom or a bromine atom, or an aryl group such as a phenyl group or a naphthyl group, and a hydrogen atom is preferable. . Specific examples of these binder resins are shown in Table 3 below, but are not limited thereto.

[0037]

[Table 6]

[0038]

[Table 7]

[0039]

[Table 8]

[0040]

[Table 9]

[0041]

[Table 10]

These binder resins may be contained in any of the charge transport layer, the charge generation layer and the single layer type photoreceptor in the case of a laminated type, but are contained in the charge transport layer and the single layer type photoreceptor. Is preferred. Along with these binder resins,
Vinyl resins such as polymethyl methacrylate, polystyrene, polyvinyl chloride, and copolymers thereof, polyesters, polysulfones, other polycarbonates, other polyarylates, polyethers, polyketones, phenoxy resins, epoxy resins, and various types of polyvinyl acetal Known resins can be used in combination.

The range which does not inhibit the effect of the present invention is usually
It is 50% by weight or less of the whole binder resin. In the case of a laminated photoreceptor, the content of the charge generating substance in the charge generating layer is usually 20 to 500 parts by weight, preferably 50 to 30 parts by weight, based on 100 parts by weight of the binder resin.
It is used in the range of 0 parts by weight. The content of the charge transporting substance in the charge transporting layer is usually 20 to 200 parts by weight of the charge transporting substance, preferably 100 parts by weight of the binder resin,
It is used in the range of 50 to 150 parts by weight.

In the case of a single-layer type photoreceptor, 1 to 50 parts by weight of a charge generating substance is added to 100 parts by weight of a binder resin.
Preferably, the amount of the charge transport material 2 is in the range of 3 to 30 parts by weight.
It is used in the range of 0 to 200 parts by weight, preferably 50 to 150 parts by weight. Various additives such as a leveling agent, an antioxidant, and a sensitizer may be added to the photosensitive layer for the purpose of improving film formability, flexibility, durability, and the like. In the case of a laminated type photoreceptor, the film thickness of the photosensitive layer is not more than 0.
In the range of from 0.5 to 3 μm, preferably from 0.1 to 1 μm, the charge transport layer is from 10 to 50 μm, preferably from 10 to 40 μm.
Used in the range. 10 to 5 for a single-layer type photoreceptor
It is used in the range of 0 μm, preferably 10 to 40 μm. If necessary, a protective layer may be provided on the photosensitive layer.

[0045]

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. In the following examples, “parts” means “parts by weight”. Example 1 10 parts of an azo compound having the following structure (S) was added to 150 parts of 4-methoxy-4-methyl-2-pentanone, and pulverized and dispersed by a sand grind mill.

[0046]

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The pigment dispersion obtained here was treated with polyvinyl butyral (trade name # 6000-, manufactured by Denki Kagaku Kogyo KK).
C) to a mixture of 100 parts of a 5% dimethoxyethane solution and 100 parts of a 5% dimethoxyethane solution of a phenoxy resin (trade name: PKHH, manufactured by Union Carbide Co.), and finally a dispersion having a solid content of 4.0%. A liquid was prepared. This dispersion was applied on a PET film having aluminum evaporated on the surface, and a charge generation layer was provided so that the dry film thickness was 0.4 μm. Next, 110 parts of an arylamine compound represented by the following structural formula

[0048]

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0.5 parts of a cyano compound having the following structure

[0050]

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A coating solution was prepared by dissolving 100 parts of the binder resin exemplified in 3-1 of Table 3 and 8 parts of 2,6-ditert-butylhydroxytoluene in a mixed solvent of 164 parts of dioxane and 305 parts of tetrahydrofuran. did. This coating solution was applied on the charge generation layer, and a charge transfer layer was provided so that the film thickness after drying was 35 μm, to obtain a photoreceptor. The photoconductor thus obtained is referred to as Sample 1-A.

Next, 3-6, 3-7, and 3-10 in Table 3 (unit ratio: 40: 6) were used as the binder resin for the charge transport layer.
0), 3-13 (unit ratio 52:48), 3-19
(Sample ratio 1-B, 1-C, 1-C) in the same manner as Sample 1-A except that the resins exemplified in (Unit ratio 42:38:20) and 3-22 (Unit ratio 80:20) were used.
D, 1-E, 1-F and 1-G were prepared (unit ratio;
Molar ratio).

Comparative Example 1 Comparative sample 1-H was prepared in the same manner as sample 1-A, except that a polycarbonate resin having the following structure (A) was used as the binder resin for the charge transport layer.

[0054]

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Example 2 A sample 2-A was prepared in the same manner as in the sample 1-C, except that a compound having the following structure (T) was used as the charge generating substance.

[0056]

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Next, samples 2-B and 2-B were prepared in the same manner as in sample 2-A, except that the resins exemplified in 3-10 and 3-13 of Table 3 were used as the binder resin for the charge transport layer.
C was created. Comparative Example 2 Comparative sample 2-D was made in the same manner as sample 2-A, except that the polycarbonate resin used in comparative sample 1-H was used as the binder resin for the charge transport layer. Comparative Example 3 Comparative sample 3-A was prepared in the same manner as in Sample 1-C, except that a compound having the following structure (U) was used as the charge generating substance.
It was created.

[0058]

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Next, Comparative Sample 3-B was prepared in the same manner as Sample Comparative Sample 3-A, except that the resin exemplified in 3-10 of Table 3 was used as the binder resin for the charge transport layer.
It was created. The chargeability (V ₀ ), white light sensitivity (half-exposure amount E _1/2 ), and residual potential (Vr) of the photoreceptor prepared as described above were measured using a photoreceptor characteristic measuring device (EP manufactured by Kawaguchi Electric Co., Ltd.).
A8100). Table 4 shows the results.

A photoreceptor film is wound around an alumina cylinder having an outer diameter of 80 mm and a length of 348 mm, and charge-exposure-discharge elimination corresponding to 300,000 A4 transverse feeds is repeated by a commercially available copying machine at a copy speed of 50 sheets / min. went. At this time, changes in black background potential (initial about -700 V): Vd, exposure potential (initial about -300 V): VL, and residual potential: Vr are shown in Table.
It is shown in FIG. Table 5 shows the stability over time of the charge transport layer coating solution used for preparing each sample. As is evident from these results, the photoreceptor using the charge generating substance of the present invention and the binder resin exhibits extremely excellent sensitivity, durability, and stability of the coating solution, while the comparative sample shows satisfactory results. It turns out that it cannot be obtained.

[0061]

[Table 11]

[0062]

[Table 12] Table-5 State of coating solution for charge transport layer Sample resin after preparation of binder solution 0 day 7 days after 60 days Example 1-A 3-1 good good good good good 1-B 3-6 １− 1-C 3-7 〃 〃 1-D 3-10 〃 〃 1-E 3-13 〃 〃 1-F 3-19 〃 〃 1-G 3-22 〃 比較 Comparative Example 1 H (A) ゲ ル Gelation Solidification

[0063]

The electrophotographic photoreceptor using the specific charge generating substance according to the present invention and the specific binder resin is excellent in both initial characteristics such as sensitivity and durability against mechanical and electrical deterioration. I have.

Claims (14)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, wherein at least the charge generating substance is represented by the following general formula (1):
An electrophotographic photoreceptor comprising an azo compound represented by the formula: and a resin having a unit having a structure represented by the following general formula (2) as a binder resin. Embedded image A carbon atom to which the azo group is bonded, represents a divalent group which is a SP ² type carbon atoms forming the double bond, R represents an alkyl group which may have a substituent. Y is a hydrogen atom,
Represents a halogen atom, an alkyl group or an alkoxy group. ) (R _1-10 each independently represents a hydrogen atom, an alkyl group, a halogen atom or an aryl group, and R ₅ and R ₆ may form a ring with each other, provided that R _1-4 and R _7-10 Is a hydrogen atom and a homopolymer in which R _5,6 is a methyl group is excluded.) 2. The electrophotographic photosensitive member according to claim 1, wherein R _{1-4 and 7-10 in the} general formula (2) are each independently a hydrogen atom or an optionally substituted alkyl group. . 3. The compound according to claim 1, wherein R _{1-4 and 7-10 in the} general formula (2) are each independently a hydrogen atom or an optionally substituted C _1-3 alkyl group. Electrophotographic photoreceptor. 4. The electrophotographic photosensitive member according to claim 1, wherein R _{1-4 and 7-10 in the} general formula (2) are each independently a hydrogen atom or a methyl group. 5. R _{5-6 in the} formula (2) are each independently a hydrogen atom or an optionally substituted alkyl group, aryl group, or R ₅ and R ₆ which form a ring with each other. 5. The electrophotographic photoreceptor according to claim 1, wherein: 6. R _{5-6 in the} general formula (2) are each independently a hydrogen atom or an optionally substituted C _1-3 alkyl group, phenyl group, or R ₅ and R ₆ are bonded to each other. C
_5. The electrophotographic photoreceptor according to claim 1, wherein said electrophotographic photoreceptor is a ring of _3-6 . 7. The compound according to claim 2, wherein R _{5-6 in the} general formula (2) are each independently a hydrogen atom or a methyl group, a phenyl group, or a cyclohexane ring in which R ₅ and R ₆ are bonded to each other. 5. The electrophotographic photosensitive member according to any one of items 1 to 4. 8. The electron according to claim 1, wherein the binder resin comprises a copolymer having at least a unit represented by the general formula (2) and a unit represented by the following structure (3). Photoreceptor. Embedded image 9. The electron according to claim 1, wherein the binder resin contains a copolymer having at least a unit represented by the general formula (2) and a unit represented by the following structure (4). Photoreceptor. Embedded image 10. The electron according to claim 1, wherein the binder resin contains a copolymer having at least a unit represented by the general formula (2) and a unit represented by the following structure (5). Photoreceptor. Embedded image R _11-18 each independently represent a hydrogen atom, an alkyl group,
Represents a halogen atom or an aryl group. 11. The electrophotographic photosensitive member according to claim 10, wherein R _{11-18 in the} general formula (5) are each independently a hydrogen atom or an optionally substituted alkyl group. 12. The electron according to claim 1, wherein the binder resin contains a copolymer having at least a unit represented by the general formula (2) and a unit represented by the following structure (6). Photoreceptor. Embedded image R _19-26 each independently represent a hydrogen atom, an alkyl group,
Represents a halogen atom or an aryl group. 13. The electrophotographic photoreceptor according to claim 12, wherein R _{19-26 in the} general formula (6) are each independently a hydrogen atom or an optionally substituted alkyl group. 14. The electrophotographic photosensitive member according to claim 1, wherein the ratio of the unit represented by the general formula (2) is 5 to 90 mol%.