JPH01302260A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance a photosensitive body in storage stability for a long period by incorporating a hydroquinone derivative and an organic phosphite compound in a photosensitive layer. CONSTITUTION:The photosensitive layer of said photosensitive body contains the hydroquinone derivative such as 2,5-di-t-butylhydroquinone as an antioxidant, and the organic phosphite compound such as tris(2,4-di-t-butylphenyl)phosphite for preventing deterioration of said hydroquinone derivative, and it is preferred to use for the photosensitive body a trisazo pigment of formula I or the like as an electric charge generating material and a compound of formula II as a charge transfer material, and in formulas I and II, A is a coupler residue having a phenolic OH group; each of R<1> and R<4> is H, alkyl or the like; each of R<2> and R<3> is H, phenyl, or the like; X is an atomic group necessary to form a desired ring; (n) is 0 or 1; and (m) is 0-3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor that has excellent charging stability even when used repeatedly over a long period of time.

[Prior art]

Inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been conventionally known as photoconductive materials for electrophotographic photoreceptors. However, these inorganic substances do not necessarily satisfy the characteristics such as photosensitivity, thermal stability, and durability required for electrophotographic photoreceptors, as well as the manufacturing conditions.For example, selenium has the characteristic of being easily crystallized by heat, dirt, etc. However, it has disadvantages such as being easily deteriorated, and requiring care in handling such as manufacturing cost, impact resistance, and toxicity.

Photoreceptors using cadmium sulfide have poor moisture resistance and durability, and also have problems such as toxicity. Zinc oxide also has the disadvantage of poor moisture resistance and durability.

For electrophotographic photoreceptors using these inorganic photoconductive materials,
Photoreceptors using organic photoconductive substances are being actively researched and developed because of their light weight, ease of film formation, manufacturing cost, and wide variation as organic compounds. For example, in the early days, photoreceptors containing polyvinylcarbazole and 2,4,7-trinitro-9-fluorenone described in Japanese Patent Publication No. 50-10496;
A photoreceptor in which polyvinylcarbazole is sensitized with a biryllium base dye, or a photoreceptor having a eutectic complex as a main component, as described in Japanese Patent No. 25658, has been proposed. However, these photoreceptors do not have sufficient sensitivity and durability.

Therefore, in recent years, a functionally separated type photoreceptor in which a charge generation layer and a charge transport layer are separated has been proposed, and
A photoreceptor comprising a combination of chlordiane blue and a hydrazone compound as described in JP-A-53-133445, JP-A-54-21728, and JP-A-54-22834 with a bisazo compound as the charge generating substance.
As described in the publication, the charge transport material is JP-A-58-198.
043 JP-A-58-199352 and the like are known.

However, these function-separated photoreceptors are still unsatisfactory, especially in terms of durability.In recent years, as demands for durability have increased more and more, ensuring charging stability has become an issue that cannot be ignored. . In other words, if the charging property decreases, it will cause a decrease in the image density of copies in copying machines, and in the case of laser printers that use a reversal development method, it will cause deterioration in image quality such as background stains. In order to solve
It has been proposed to provide an intermediate layer between the conductive substrate and the photosensitive layer. However, when a high-resistance material with high barrier properties is used for the intermediate layer in order to stabilize the charging property, although the charging property is improved, there are disadvantages in that the photosensitivity decreases and the residual potential increases. Furthermore, if a material with relatively low resistance that does not increase the residual potential is used, charging stability will be insufficient.

On the other hand, when a photoreceptor is actually used in a copying machine, the photoreceptor is exposed to ozone generated by a charger and is therefore subject to strong oxidation. Particularly in the case of organic photoreceptors, this effect is significant, and the materials constituting the photosensitive layer gradually oxidize and decompose, resulting in deterioration in the performance and durability of the photoreceptor. As a countermeasure, JP-A No. 57-122444,
JP-A-61-156052, JP-A-62-39863
The addition of an antioxidant to the photosensitive layer has been proposed, as shown in the above issue. However, since antioxidants prevent the oxidation of other substances by undergoing oxidation themselves, deterioration of the antioxidant itself over time cannot be avoided, and the rate of deterioration increases particularly at high temperatures. Therefore, even in a photoreceptor containing an antioxidant, when stored for a long period of time at high temperatures, the effect of increasing durability is drastically reduced due to deterioration of the antioxidant. That is, photoreceptors containing antioxidants in the form that has been proposed so far have the drawback that although they have sufficient durability initially, their durability significantly deteriorates after long-term storage.

〔the purpose〕

The present invention includes a photosensitive layer containing a substance that is extremely effective in increasing the durability of a photoreceptor.

Furthermore, by incorporating other additives into the photosensitive layer,
The purpose of the present invention is to provide a photoreceptor that has both characteristics of durability and storage stability. That is, an object of the present invention is to provide a photoreceptor having excellent ozone resistance, long life, high reliability, and excellent storage stability without deterioration of photoreceptor characteristics even during long-term storage.

〔composition〕

According to the present invention, in an electrophotographic photoreceptor in which a photosensitive layer containing a charge generating substance and a charge transporting substance is provided on a conductive support, the photosensitive layer contains a hydroquinone compound and an organic phosphite compound. An electrophotographic photoreceptor is provided.

Since the electrophotographic photoreceptor of the present invention contains a hydroquinone compound and an organic phosphite compound in the photosensitive layer, it has excellent ozone resistance and has a long life.

It has high reliability and does not deteriorate in photoreceptor characteristics even during long-term storage, and has extremely excellent storage stability.

In addition, in the present invention, a trisazo pigment or a disazo pigment represented by the following general formula (1) to general formula (m) is used as a charge generating substance, and/or a trisazo pigment or a disazo pigment represented by the following general formula [IV] is used as a charge transporting substance. When a compound is used, the above effects can be further enhanced.

(In the formula, ^ represents a coupler residue having a phenolic OH group.) (In the formula, A is a coupler residue having one phenolic OH group.) ) (In the above formula, ^ represents a coupler residue having a phenolic OH group. Ar is a substituted or unsubstituted carbocyclic aromatic residue or a heterocyclic aromatic residue.

R1, R, , R, and R4 represent a hydrogen atom, a substituted or unsubstituted alkyl group, an aralkyl group, or an electron-withdrawing group such as a cyano group, a halogen, or a nitro group. R4 represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, or a substituted amino group;
1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted phenyl group.

-Q is a benzene ring, a naphthalene ring, anthra' x -
' Indicates a sen ring, an indole ring, or a carbazole ring.

n is 0 or 1, ■ is an integer of 0, 1, 2, or 3)
Hydroquinone compounds that can be used in the present invention include hydroquinone, methylhydroquinone, 2,
3-dimethylhydroquinone, 2,5-dimethylhydroquinone, 2,6-dimethylhydroquinone, trimethylhydroquinone, tetramethylhydroquinone, t-
Butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,5-di-amylhydroquinone, chlorohydroquinone, 2,5-di-t-octylhydroquinone, 2-t-butyl-5-methylhydroquinone,
Examples include hydroquinone derivatives such as 1,4-diolnaphthalene and 9,1°-diolanthracene, but 2°5-di-t-butylhydroquinone is particularly preferred in view of its effectiveness.

Further, in the present invention, two or more of the above hydroquinone compounds can be used in combination.

Examples of organic phosphite compounds that can be used in the present invention include tris(nonylphenyl)phosphite, tris(p-tart-octylphenyl)phosphite,
Tris (2,4,6-tris(α-phenylethyl))
Phosphite, tris(P-2-butenylphenyl)phosphite, bis(p-nonylphenyl)cyclohexylphosphite, tris(2,4-di-tert-butylphenyl)phosphite, di(2,4- gtert
-butylphenyl)pentaerythritol diphosphite, distearylpentaerythritol diphosphite, 4,4'-isopropylide-diphenol alkyl phosphite, tetratridecyl-4,4'-butylidene-bis(3-methyl-6- tert-butylphenol) diphosphite, tetrakis(2,4-di-tert
-butylphenyl)-4,4'-biphenylene diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphite, 2
, 6-tert-butyl-4-methylphenyl phenyl pentaerythritol diphosphite, 2.6
-tert-butyl-4-methylphenyl methyl pentaerythritol diphosphite, 2,6-sheet
rt-Butyl-4-ethylphenyl stearyl pentaerythritol diphosphite, di(2,6-ter
t-Butyl-4-methylphenyl)pentaerythritol diphosphite, 2,6-tert-amyl-4
Examples include -methylphenyl/phenylpentaerythritol diphosphite, but two or more of these compounds may be used in combination.

The reason why a photoreceptor with excellent durability and storage stability can be obtained by containing a hydroquinone compound and an organic phosphite compound in the photosensitive layer is considered to be as follows.

When a photoreceptor is used in a copying machine, a laser printer, etc., the photoreceptor undergoes an oxidation reaction due to ozone generated during corona discharge, a photochemical reaction due to exposure and neutralizing light, and an electrochemical reaction during the copying process. Therefore, these reactions cause deterioration of the charge transport material, binder, and charge generation material, resulting in a decrease in the durability of the photoreceptor.

Addition of various antioxidants has been studied for the purpose of protecting the materials constituting the photosensitive layer from these reactions.

Among these, hydroquinone compounds not only have a large antioxidant effect, but also have good compatibility with the binder in the photosensitive layer, and are adsorbed to charge transport substances that are particularly susceptible to the above chemical reactions. Excellent ability. For this reason, it has an excellent ability to protect the photosensitive layer compared to other antioxidants, and can minimize deterioration of photoreceptor characteristics even after repeated use.

However, the antioxidant contained in the photosensitive layer does not have its antioxidant effect only during the copying process. For example, even when a photoreceptor is stored, the antioxidant itself deteriorates due to thermally generated radicals and the like. especially,
When the storage environment is high temperature, the rate of deterioration increases. In other words, if the antioxidant deteriorates due to storage environment and period, the antioxidant effect will be lost and the durability will be drastically reduced. Hydroquinone compounds are no exception. The organic phosphite compound used in the present invention prevents the deterioration of hydroquinone compounds.

It has the function of significantly increasing the storage stability of photoreceptors.

That is, the hydroquinone-based compound becomes a peroxide as a result of its deterioration, and finally becomes a quinone compound as an oxidation product. This quinone compound has no antioxidant effect; the organic phosphite compound acts on peroxide during the deterioration process and has the function of reducing it to the original hydroquinone compound.

Therefore, the life of the antioxidant is greatly improved, and the storage stability of the photoreceptor is also improved. This is the optimal combination of a hydroquinone compound and an organic phosphite compound; for example, sulfur-based antioxidants have almost no effect on improving the shelf life of hydroquinone compounds. This is considered to be due to the adsorption ability for hydroquinone compounds or the difference in energy level in the oxidation-reduction process.

[n
) and the disazo pigments represented by the general formula (m) are used, but it is preferable to use those in which the coupler residue (A) is the following group.

[Coupler residue wholesaler] R2 'x) 1・Yξ, υ■ , /’Y4゜ 'zノ 'zノ Ar.

(In the formula, X is a naphthalene ring fused with a benzene ring,
Represents a residue necessary to form a polycyclic aromatic ring or a petero ring selected from anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring and diphenylene sulfide ring, R6 and R6 are hydrogen atoms, substituted or unsubstituted Represents a group selected from alkyl, aralkyl, aryl, and heterocyclic group, R,, R, may form a cyclic amino group together with the bonded nitrogen atom, R,, R, is a substituted or unsubstituted alkyl group , an aralkyl group and an aryl group, Y' is a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring, Fist
Rl. , R Engineering 1. R1□ represents a hydrogen atom, a substituted or unsubstituted alkyl group, an aralkyl group, an aryl group, and a heterocyclic group, and R□1. R1□ may form a 5- or 6-membered ring, and in this case, this 5- or 6-membered ring may have a fused aromatic ring.

2 is necessary to form a polycyclic aromatic ring or a petero ring selected from naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring and diphenylene sulfide ring condensed with a benzene ring; Residues are shown. Ar2 is an aromatic ring such as a benzene ring or a naphthalene ring, and a substituent thereof, L
(i, R14 represents hydrogen, a lower alkyl group, a carboxyl group, or an ester thereof) Specific examples of the trisazo pigment represented by the general formula [1) that can be used in the present invention are shown below.

Specific examples of the disazo pigment represented by the general formula [II] used in the present invention are shown below.

(ii) Specific examples of the disazo pigment represented by the general formula [III] used in the present invention are shown below.

〇 〇 −
″′ ″′ E＾
^
＾８ 〇
−＾ ＾
6th Ward Miya
m-! enemy ν^
^
Other charge-generating substances that can be used in the present invention include: - Perylene pigments such as perylene anhydride and perylene imide.

■Indigo pigment.

■Quinacridone pigment.

■Polycyclic quinones such as anthraquinones, birequinones, anthoanthros, and flavanthrones.

■Bisbenzimidazole pigment.

■Squaric methine pigment.

■Indathlon pigment.

(Phthalocyanine pigments such as metal phthalocyanines and metal-free phthalocyanines, such as luphthalocyanine.

Examples include azulenium salt compounds such as monoazo pigments having central skeletons such as anthraquinone and N-phenylcarbazole.

In the present invention, a compound represented by the general formula (IVI) is preferably used as the charge transport material, and specific examples thereof are shown below.

Further, other charge transport materials that can be used in the present invention include hole transport materials and electron transport materials. As the hole transport substance, for example, the following general formulas (1) to (12) are used.
Examples include the compounds shown below.

C1 [wherein R represents a methyl group, ethyl group, 2-hydroxyethyl group or 2-chloroethyl group, R2 represents a methyl group, ethyl group, benzyl group or phenyl group, R
1 represents hydrogen, chlorine, bromine, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a dialkylamino group, or a 21-ro group. ] [In the formula, Ar is naphthalene,
It represents anthracenes, styryl groups and substituted products thereof, pyridines, furans, and thiophenes, and R represents an alkyl group or a benzyl group. ] l(.

[In the formula, R is an alkyl group, a benzyl group, a phenyl group,
Represents a naphthyl group, R2 represents hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group, a dialkylamino group, or a diarylamino group, and n represents an integer of 1 to 4. When n is 2 or more, R2 may be the same or different. R1 represents hydrogen or a methoxy group. ] [In the formula, R1 has 1 to 1 carbon atoms
11 alkyl group, substituted or unsubstituted phenyl group, or heterocyclic group, R2 and R3 may be the same or different, and hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a chloroalkyl group, It represents a substituted or unsubstituted aralkyl group, and R2 and R3 may be bonded to each other to form a nitrogen-containing heterocycle. R4 may be the same or different and represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a halogen. [In the formula, R represents hydrogen or a halogen atom, and Ar represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group, or carbazolyl group. [In the formula, R represents hydrogen, halogen, a cyano group, an alkoxy group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms, and Ar and Ro represent an alkyl group having 1 to 4 carbon atoms, R2, R,
represents hydrogen, halogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a dialkylamino group, and n is 1 or 2, and when n is 2, R1 is the same or different. R4 and R9 each represent hydrogen, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted benzyl group, [wherein R is a carbazolyl group, a pyridine group, a thienyl group, an indolyl group] base,
A furyl group or a substituted or unsubstituted phenyl group, styryl group, naphthyl group or anthryl group, in which the substituent is a dialkylamino group, an alkyl group, an alkoxy group, a carboxy group or an ester thereof, or a halogen atom.

Represents a group selected from the group consisting of cyano group, aralkylamino group, N-alkyl-N-aralkyl amino group, amino group, nitro group and acetylamino group] R3 [wherein R1 is a lower alkyl group or benzyl group] group or a substituted or unsubstituted aryl group, R2 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a halogen atom, a nitro group, an amino group, or an amino group substituted with a lower alkyl group or a benzyl group, and n represents an integer of 1 or 2. [In the formula, R represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and R2
and R1 represents an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group;
4 represents a hydrogen atom or a substituted or unsubstituted phenyl group, and Ar represents a phenyl group or a naphthyl group. [In the formula, n is O or an integer of 1, R represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted phenyl group, and A represents a 9-anthryl group or a substituted or unsubstituted N-alkylcarbazolyte. R4 represents a hydrogen atom,
Alkyl group, alkoxy group, halogen atom alkyl group,
represents a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, R9 and R6 may form a ring), n+ is an integer of 0, 1.2 or 3, and m is When 2 or more, R4 may be the same or different.] [In the formula, R1, R, and R1 represent hydrogen, a lower alkyl group, a lower alkoxy group, a dialkylamino group, or a halogen atom, and n is 0 or 1. represents. ] [During the ceremony,
R1 represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and R1 and R1 may be the same or different and represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom. ] The compound represented by the general formula (1) includes, for example, 9-ethylcarbazole-3-aldehyde-1-methyl-1-
Phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1-benzyl-1-phenylhydrazone, 9
-ethylcarbazole-3-aldehyde-1,1-diphenylhydrazone and the like.

The compound represented by the general formula (2) includes, for example, 4-diethylaminostyrene-β-aldehyde-1-methyl-
1-phenylhydrazone, 4-methoxynaphthalene-1
-Aldehyde-1-benzyl-1-phenylhydrazone and the like.

Examples of the compound represented by general formula (3) include 4-medoxybenzaldehyde-1-methyl-1-phenylhydrazone, 2,4-dimethoxybenzaldehyde-1-
Benzyl-1-phenylhydrazone, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone,
4-methoxybenzaldehyde-1-benzyl-1-(
Examples include 4-methoxy)phenylhydrazone, 4-diphenylaminobenzaldehyde-1-benzyl-1-phenylhydrazone, and 4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone.

The compound represented by general formula (4) includes, for example, 1.1
-Bis(4-dibenzylaminophenyl)propane, tris(4-diethylaminophenyl)methane, 1.1-
Bis(4-dibenzylaminophenyl)propane, 2.
2'-dimethyl-4,4'-bis(diethylamino)-
Examples include triphenylmethane.

The compound represented by general formula (5) includes, for example, 9-(
Examples include 4-diethylaminostyryl)anthracene, 9-promo-1O-(4-diethylaminostyryl)anthracene, and the like.

The compound represented by general formula (6) includes, for example, 9-(
4-dimethylaminobenzylidene) fluorene, 3-(
Examples include 9-fluorenylidene)-9-ethylcarbazole.

The compound represented by general formula (7) includes, for example, 1.2
-bis(4-diethylaminostyryl)benzene.

1.2-bis(2,4-dimethoxystyryl)benzene.

Examples of the compound represented by the general formula (8) include 3-styryl-9-ethylcarbazole and 3-(4-methoxystyryl)-9-ethylcarbazole.

Examples of the compound represented by the general formula (9) include 4-diphenylaminostilbene, 4-dibenzylaminostilbene, 4-ditolylaminostilbene, ■-(4-diphenylaminostyryl)naphthalene, 1-(4-diethylaminostilbene), and 1-(4-diethylaminostilbene). styryl) naphthylene, etc.

The compound represented by the general formula (10) includes, for example, 4'
-diphenylamino-α-phenylstilbene, 4'-
Examples include methylphenylamino-α-phenylstilbene.

The compound represented by the general formula (11) includes, for example, 1-
Phenyl-3-(4-diethylaminostyryl)-5-
(4-diethylaminophenyl)pyrazoline, 1-phenyl-3-(4-dimethylaminostyryl)-5-(4
-dimethylaminophenyl)pyrazoline, etc.

The compound represented by general formula (12) includes N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(
1,1'-bisphenyl)-4,4'-diamine, N
, N'diphenyl-N,N'-bis(chlorophenyl)
-(1,1'-biphenyl]-4,4'-diamine, 3
, 3'-dimethylbenzidine, etc.

Other hole transport substances include, for example, 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole, 2,5-bis(4-(4-diethylaminostyryl)phenyl)- 1,3,4-oxydiazole, 2-(9-ethylcarbazolyl-3-)-5-(4
oxadiazole compounds such as -diethylaminophenyl)-1,3,4-oxadiazole, 2-vinyl-4
There are low molecular weight compounds such as oxazole compounds such as -(2-chlorophenyl)-5-(4-diethylaminophenyl)oxazole and 2-(4-diethylaminophenyl)-4-phenyloxazole. Also, poly-N-
Polymer compounds such as vinyl carbazole, halogenated poly-N-vinyl carbazole, polyvinyl pyrene, polyvinylanthracene, pyrene formaldehyde resin, and ethyl carbazole formaldehyde resin can also be used.

Examples of the electron transport substance include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-dolinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone,
2,4,5.7-titranitroxanthone, 2,4°8
-trinidrothioxanthone, 2,6.8-trinitro-4H-indeno(1,2-b)thiophen-4-one, 1,3.7-dolinitrodibenzothiophene-5,5
- Dioxide, etc.

The photosensitive layer of the electrophotographic photoreceptor of the present invention can be of a dispersed type or a functionally separated type by combining a charge generating substance and a charge transporting substance.

In the case of a dispersed layer structure, a photosensitive layer in which a charge generating substance and a charge transporting substance are dispersed in a binder is provided on a conductive substrate.

In the case of a functionally separated type, a charge generation layer containing a charge generation substance and a binder is formed on the substrate, and a charge transport layer containing a charge transport substance and a binder is formed on top of the charge generation layer. charge generation layer if applicable.

The charge transport layer may be laminated in the reverse manner. In the case of a functionally separated type, a charge transport substance may be contained in the charge generation layer. In particular, in the case of a positively charged structure, the sensitivity is improved.

Furthermore, an intermediate layer may be provided between the photosensitive layer and the substrate in order to improve adhesion and charge blocking properties. Furthermore, a protective layer may be provided on the photosensitive layer in order to improve mechanical durability such as abrasion resistance. Binders used in forming the charge generation layer, charge transport layer and dispersed photosensitive layer include polycarbonate (bisphenol A type, bisphenol A type), polyester, methacrylic resin, acrylic resin,
Polyethylene, vinyl chloride, vinyl acetate, polystyrene, phenolic resin, epoxy resin, polyurethane, vinylidene chloride, alkyd resin, silicone resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyarylate, polyacrylamide, polyamide, phenoxy resin, etc. are used. . These binders can be used alone or as a mixture of two or more.

When producing a photoreceptor using the above-mentioned layer structure and materials, there are preferable ranges for the film thickness and the proportions of the materials.

In the case of a negatively charged type (laminated substrate/charge generation layer/charge transport layer), in the charge generation layer, the ratio of the charge generation substance to the binder is preferably 20 to 500 mm by weight, and the film thickness is preferably 0.1 to 57 mm. . In the charge transport layer, the ratio of the charge transport substance to the binder is 20 to 200% by weight, and the film thickness is 5 to 50% by weight.
- is preferable.

In the case of a positively charged type (substrate/charge transport ft!J/stack of charge generation layer), in the charge transport layer, the ratio of the charge transport substance to the binder is 20 to 200% by weight, and the film thickness is 5 to 5% by weight.
It is preferable to use 0 voice. In the charge generation layer, the charge generation substance is preferably contained in an amount of 10 to 100% by weight based on the binder. Furthermore, it is preferable to include a charge transporting substance in the charge generation layer, which has the effect of suppressing residual potential and improving sensitivity. In this case, the charge transport material is preferably contained in an amount of 20 to 200% by weight based on the binder.

In addition, the amount of the hydroquinone compound of the present invention to be added to the photosensitive layer is 0.01 to 5.0 parts by weight based on the charge transport material in the case of a functionally separated type and when added to the charge transport layer. Preferably, when added to the charge generation layer, the amount is preferably 0.1 to 20.0% by weight2 relative to the charge generating material.0 In the case of a dispersed type, the amount is preferably 0.01 to 20.0% by weight relative to the charge transporting material.
-5.0% by weight is preferably added.

If the amount of the hydroquinone compound added is less than the lower limit, the effect of increasing durability cannot be obtained, and if it is more than the upper limit, adverse effects such as decreased sensitivity may occur.

On the other hand, the amount of the organic phosphite compound of the present invention added is 25 to 100% of the amount of the hydroquinone compound added.
It is preferably 0% by weight, more preferably 50 to 800% by weight. If it is less than this, the effect of improving storage stability cannot be obtained, and if it is more than this, it will precipitate due to compatibility with the photosensitive layer. There is a risk.

Hydroquinone compounds and organic phosphite compounds are
In the case of a functionally separated photoreceptor, it may be added to either the charge generation layer or the charge transport layer.This is done when coating the photosensitive layer by dispersing the hydroquinone compound or organic phosphite compound using the coating liquid dispersion medium or solvent. This is thought to be due to active diffusion to other layers.

However, preferably, the hydroquinone compound and the organic phosphite compound are added to the coating solution of the same layer, and in this case, the storage stability of the prepared coating solution is greatly improved.

Generally, the intermediate layer provided as needed is mainly composed of resin, but considering that the photosensitive layer is coated on top of it with a solvent, these resins have a high solvent resistance to general organic solvents. It is desirable that the resin has high properties. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate; alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon; and three-dimensional resins such as polyurethane, melamine resin, phenolic resin, and epoxy resin. Examples include curable resins that form a network structure.

Further, fine powder pigments of metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the intermediate layer to prevent moire and reduce residual potential.

Examples of the solvent or dispersion medium used in forming the charge generation layer and the charge transport layer include N,N'-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, 1,2-dichloroethane, Dichloromethane, monochlorobenzene, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate,
Examples include butyl acetate, dimethyl sulfoxide, and the like.

The photosensitive layer can be formed by immersing the substrate in a coating solution for the charge generation layer or charge transport layer, or by spraying the coating solution onto the substrate.

Substrates used in the electrophotographic photoreceptor of the present invention include metal drums and sheets made of aluminum, brass, stainless steel, nickel, etc., materials such as polyethylene terephthalate, polypropylene, nylon, paper, etc., on which metals such as aluminum and nickel are vapor-deposited. , or titanium oxide,
Examples include sheet-like or cylindrical substrates such as plastics and paper that are coated with a conductive substance such as tin oxide or carbon black together with a suitable binder to conductivity treatment.

〔effect〕

Since the electrophotographic photoreceptor of the present invention has the above-mentioned structure, the photoreceptor characteristics such as charging properties do not deteriorate even after repeated use over a long period of time, and the storage stability is good, so that it has extremely high practical value. be.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Alcohol-soluble polyamide (Amilan CM-8000
; manufactured by Toshisha Co., Ltd.) was dissolved in a mixed solvent of 8 parts by weight of methanol and 5 parts by weight of n-butanol. 3 parts by weight of titanium oxide powder (Tybake A-100, manufactured by Ishihara Sangyo Co., Ltd.) was added to this and dispersed in a ball mill for 12 hours to prepare a coating liquid for an intermediate layer. This has a major diameter of φ40m+n and a length of 255II.
It was coated on an I+ aluminum drum by dip coating and dried to form an intermediate layer with two thicknesses.

Next, polyvinyl butyral resin (S-LEC BL-8;
(manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 125 parts by weight of 1,2-dichloroethane, and 1 part by weight of X-type metal-free phthalocyanine prepared in the same manner as described in Japanese Patent Publication No. 49-4338 was added. , ultrasonic dispersion was performed using an ultrasonic dispersion machine. The charge generation layer coating solution thus obtained was applied onto the intermediate layer by dip coating and dried to a film thickness of 0.5.
A charge generation layer of pm was formed.

Furthermore, 8 parts by weight of a charge transport substance represented by the following structural formula (1), C, H.

10 parts by weight of polycarbonate resin (Panlite 1300; manufactured by Teijin Kasei Co., Ltd.), 0.002 parts by weight of silicone oil (NiF-50; manufactured by Shin-Etsu Chemical Co., Ltd.), 2,5-GTE
0.04 parts by weight of rt-butylhydroquinone, Tris(
A charge transport layer coating solution was prepared by dissolving 0.08 parts by weight of 2,4-di-tert-butylphenyl) phosphite in 85 parts by weight of methylene chloride. This was coated on the charge generation layer by dip coating and dried to form a charge transport layer with a film JI'A of 20 μm.

In this manner, the electrophotographic photoreceptor of the present invention was produced.

Examples 2 to 8 The same procedure as in Example 1 was carried out except that 2,5-di-tart-butylhydroquinone and tris(2,4-di-tart-butylphenyl) phosphite in Example 1 were changed as shown in Table-1. Each electrophotographic photoreceptor of the present invention was prepared.

Table-1 Structural formula (n) Structural formula (m) Comparative examples 1 to 4 The same procedures as in Examples 1, 3, and 5.7 were performed except that the organic phosphite compound was removed. Electrophotographic photoreceptors of Comparative Examples 1 to 4 were prepared.

Comparative Example 5 An electrophotographic photoreceptor of Comparative Example 5 was prepared in the same manner as in Example 1 except that distearyl thiodipropionate was added instead of tris(2,4-di-tert-butylphenyl)phosphite in Example 1. It was created.

Example 9 The charge generation layer of Example 1 was coated with 0.03 parts of 2,5-di-tart-butylhydroquinone and tris(2,4
-di-tart-butylphenyl) phosphite at 0.
06 parts by weight of 2.5-di-tart-butylhydroquinone, 1 to lith(2,4-
Electrophotography 1 (photoreceptor) was prepared in the same manner as in Example 1 except that the di-tart-butylphenyl) phosphite was removed.

The electrophotographic photoreceptor obtained as described above was installed in a laser printer (PC-LASIEI+-6000; manufactured by Ricoh) and evaluated. Evaluation is after photoreceptor production, 24
The surface potentials of the electrophotographic photoreceptor that had been left in the dark at 1111 hours and the electrophotographic photoreceptor that had been stored in a constant temperature bath at 60° C. for 2 months after the photoreceptor was prepared were measured at the initial stage and after 20,000 copies had been copied. The surface potential can be determined by removing the developing device and attaching a surface electrometer probe to the developing position.
I did 11 tests. The results obtained are shown in Table-2.

Table 2 Example 10 An intermediate layer was formed on an aluminum 11 drum in the same manner as in Example 1, and the charge transport layer coating solution shown in Example 1 was applied to the intermediate layer by dip coating. , and dried to form a charge transport layer having a thickness of 20 μm.

Next, polycarbonate resin (Panrai 1-L-1250
; manufactured by Teijin Chemicals) 117 parts of 4 parts and 200 parts of 1,2-dichloroethane! +(part, 1,1.2-h rikuuuxtan 2
To this was added 1 part of X-ray-free metal phthalocyanine II shown in Example 1, and the dispersion was carried out using an ultrasonic dispersion machine. A coating solution for charge generation 1t11 was prepared by adding 3 parts by weight of a charge transporting substance represented by +1:i structure 41 formula (1) to the solution. The electrophotographic photoreceptor of the present invention was prepared by spray coating and drying to form a charge generation layer approximately 3-3 times thick.

Comparative Example 6 Charge transport from Example 1O to Lis (2,4-La
An electrophotographic photoreceptor of Comparative Example 6 was prepared in the same manner as in Example 1O except that rt-butylphenyl) phosphite was omitted.

Example 11 Intermediate) P was placed on an aluminum drum in the same manner as in Example 1.
Next, 20 parts by weight of polycarbonate resin (Panlite -1300; manufactured by Teijin Kasei Co., Ltd.) was added to 1.2 parts by weight.
Example 1 was dissolved in 250 parts by weight of dichloroethane.
5 weight parts of type "F-wave dispersion was performed. Furthermore, 15 parts by weight of the charge transport substance represented by the structural formula (1) and 0.5 parts by weight of 2.5-di-amylhydroquinone were added to the 1-117 dispersion.
08 parts by weight and 0.15 parts by weight of 1-lith(2,4-di-tart-butylphenyl) phosphite were added and dissolved to prepare a photosensitive coating solution. A photoreceptor having a film thickness of 16 μm was applied to the intermediate layer by a coating method and dried to prepare a photoreceptor of the present invention.

Comparative Example 7 Tris (2,4-tert) was added from the photosensitive layer of Example 11.
An electrophotographic photoreceptor was prepared in the same manner as in Example 11 except that -butylphenyl)phosphite 1- was removed.

The electrophotographic photoreceptors obtained in Example 1O111 and Comparative Example 6.7 were processed using a laser printer (PC-1, AsL:R-6).
The evaluation was carried out using a modified version of 000;

The modifications included reversing the polarity of the charger and various biases, and making the charger, static elimination lamp, and laser writing system work even without paper being passed through. Furthermore, the developing device was removed so that a surface electrometer probe could be attached to the developing position. The evaluation was performed by measuring the initial surface potential and after 20,000 copies of an electrophotographic photoreceptor that was left in the dark for 24 hours after photoreceptor production, and an electrophotographic photoreceptor that was stored in a constant temperature bath at 60°C for two months after photoreceptor production. I went there. The results obtained are shown in Table 3.

Table-3 Example [2 Alcohol-soluble polyamide (Amilan CM-8000
; manufactured by Toshisha Co., Ltd.) was dissolved in a mixed solvent of 8 parts by weight of methanol and 5 parts by weight of n-butanol. Add 3 titanium oxide powder (Tiebake A-100, Ishihara Sangyo Co., Ltd.'l5) to this.
Parts by weight were added, and a coating solution for an intermediate layer was prepared using a ball mill for 12 hours. This has a major axis of φ40nto and a length of 2
It was coated on a 55 m aluminum tram using a dip coating method and dried to form an intermediate layer with a thickness of 2 IJm.

Next, polyvinyl butyral resin (S-LEC BL-8:
Sekisui Chemical Co., Ltd.) 5 parts by weight were dissolved in 150 parts by weight of cyclohexanone, 10 parts by weight of the trisazo pigment of Exemplary Compound No. (42) was added thereto, dispersed for 48 hours in a ball mill, and further 210 parts by weight of cyclohexanone was added. Dispersion was carried out for 3 hours. This was taken out into a container and diluted with cyclohexanone so that the solid content was 1.5% by weight. The charge generation layer coating liquid thus obtained was applied onto the intermediate layer by dip coating and dried to form a charge generation layer having a thickness of 0.2 m.

Furthermore, 8 parts by weight of a charge transport substance shown in the following formula [IV], 10 parts by weight of polycarbonate resin (Panlite-1300; manufactured by Teijin Kasei Co., Ltd.), and silicone oil (KF-50;
Shin-Etsu Chemical Co., Ltd.) 0.002 parts by weight, 2,5-Gt
0.04 parts by weight of ert-butylhydroquinone and 0.08 parts by weight of tris(2,4-di-tart-butylphenyl) phosphite were dissolved in 85 parts by weight of methylene chloride,
A charge transport layer coating solution was prepared. This was coated on the charge generation layer by dip coating and dried to form a charge transport layer having a thickness of 20 coats.

In this manner, the electrophotographic photoreceptor of the present invention was produced.

Examples 13 to 19 The same procedure as in Example 12 was carried out except that 2,5-di-tart-butylhydroquinone and tris(2,4-di-tert-butylphenyl)phosphite in Example 12 were changed as shown in Table-1. Each electrophotographic photoreceptor of the present invention was prepared.

Table 4 Structural Formula (n) Structural Formula (III) Comparative Examples 8 to 11 Examples 12, 14, 16, and 18 except that the organic phosphite compound was removed, respectively. ．． 1
Electrophotographic photoreceptors of Comparative Examples 8 to 11 were prepared in the same manner as in 6.18.

Comparative Example 12 Electrophotographic photoreceptor of Comparative Example 12 was produced in the same manner as in Example 12 except that distearylthiodipropionate was added instead of tris(2,4-d-tert-butylphenyl)phosphite. It was created.

Example 20 In the charge generation layer of Example 12, 0.03 parts by weight of 2,5-di-tert-butylhydroquinone and tris(2,4-
Di-tart-butylphenyl) phosphite 0.0
6 parts by weight, and further 2,5-T from the charge transport layer.
An electrophotographic photoreceptor was prepared in the same manner as in Example 12 except that ert-butylhydroquinone and tris(2,4-di-tart-butylphenyl) phosphite were removed.

Example 21 In Example 12, the charge generating substance was exemplified by the compound 58
) An electrophotographic photoreceptor was produced in the same manner as in Example 12 except that

The electrophotographic photoreceptor obtained as described above was printed on a laser printer (PC-LASER-6000: ■ manufactured by Ricoh).
was installed and evaluated. The evaluation was performed on an electrophotographic photoreceptor that was left in a dark place for 24 hours after photoreceptor production, and an electrophotographic photoreceptor that was stored for two months in a thermostat at 60°C after photoreceptor production.
This was done by measuring the surface potential after copying oooo sheets. For the first surface mold position, the developing device was removed and the measurement was carried out by attaching a surface electrometer probe to the developing position.

The results obtained are shown in Table-5.

Table 5 Example 22 An intermediate layer was formed on an aluminum drum in the same manner as in Example 12, and the charge transport layer coating solution shown in Example 12 was applied onto the intermediate layer by dip coating and dried to form a film. A charge transport layer with a thickness of 20 μm was created.

Next, polycarbonate resin (Panlite L-1250;
(manufactured by Teijin Chemicals) 10 parts by weight of 1,2-dichloroethane 7
It was dissolved in a mixed solvent of 5 parts by weight and 75 parts by weight of 1,1.2-trichloroethane, and 3 parts by weight of the triazo pigment of Exemplified Compound (42) was added thereto, followed by dispersion in a ball mill for 48 hours. Further, this dispersion was added with 3 parts by weight of a charge transporting substance represented by the above structural formula (1), and 150 parts by weight of l,2-dichloroethane.
ffiIS and 150 parts of 1,1,2-trichloroethane were added and dispersed and dissolved in a ball mill for 24 hours to prepare a charge generation layer coating solution. This was spray-coated on the charge transport layer and dried to form a charge generation layer with a thickness of 3IJa,
An electrophotographic photoreceptor was created.

Comparative Example 13 Tris (2,4-dite) was added from the charge transport layer of Example 22.
An electrophotographic photoreceptor of Comparative Example 13 was prepared in the same manner as in Example 22 except that rt-butylphenyl) phosphite was removed.

Example 23 First, an intermediate layer was formed on an aluminum drum in the same manner as in Example 12, and then 20 parts by weight of polycarbonate resin (Panlite -1300: manufactured by Konjin Kasei Co., Ltd.) was dissolved in 100 parts by weight of tetrahydrofuran, and then 50 parts by weight of alane and 6 parts by weight of the trisazo pigment of exemplified compound Nα (42) were added, followed by dispersion in a ball mill for 48 hours. Further, in the dispersion, 15 parts by weight of the charge transport substance represented by the structural formula [IV], 0.08 parts by weight of 2.5-tert-butylhydroquinone, and 0 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite 15 parts by weight and 50 parts by weight of cyclohexanone were added and dissolved to prepare a photosensitive layer coating solution. This coating solution was applied onto the intermediate layer by a coating method and dried to form a photosensitive layer having a thickness of 16 μm, thereby producing an electrophotographic photoreceptor of the present invention.

Comparative Example 14 Tris (2,4-tert) was added from the photosensitive layer of Example 23.
An electrophotographic photoreceptor was prepared in the same manner as in Example 12 except that the (butylphenyl) phosphite was omitted.

The electrophotographic photoreceptors obtained in Example 22.23 and Comparative Example 13.14 were processed using a laser printer (PC-LASER-6).
Evaluation was carried out using a modified version of Ricoh fIB). The modifications included reversing the polarity of the charger and various biases, and making the charger, static elimination lamp, and laser writing system work even without paper being passed through. Furthermore, the developing device was removed so that a surface electrometer probe could be attached to the developing position. For evaluation, the surface potential of the electrophotographic photoreceptor that was left in the dark for 24 hours after photoreceptor production and the electrophotographic photoreceptor that was stored for two months in a constant temperature bath at 60°C after photoreceptor production was measured at the initial stage and after 500 copies were copied. I went there. The results obtained are shown in Table-6.

Table-6 Example 24 Alcohol-soluble polyamide (Amilan CM-8000
; manufactured by Toshisha) was dissolved in a mixed solvent of 8 parts by weight of methanol and 5 parts by weight of 7-butanol. 3 parts by weight of titanium oxide powder (Tybake A-100, manufactured by Ishihara Sangyo Co., Ltd.) was added to this and dispersed in a ball mill for 12 hours to prepare a coating liquid for an intermediate layer. This has a major diameter of φ40mm and a length of 255+++
It was coated on a +n aluminum drum by a dip coating method and dried to form a two-tone intermediate layer.

Next, polyvinyl butyral resin (S-LEC BL-8;
(manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 125 parts by weight of 1,2-dichloroethane, and 1 part by weight of X-type metal-free phthalocyanine prepared in the same manner as described in Japanese Patent Publication No. 49-4338 was added. Ultrasonic dispersion was performed using an ultrasonic disperser. The charge generation layer coating solution thus obtained is applied onto the intermediate layer by dip coating.

Drying was performed to form a charge generation layer with a thickness of 0.5 μl.

Furthermore, 8 parts by weight of a charge transport substance represented by the following structural formula (1), 10 parts by weight of H, polycarbonate resin (Panlite-1300; manufactured by Teijin Chemicals), and silicone oil (KF-50;
Shin-Etsu Chemical Co., Ltd.) 0.002 parts by weight, 2,5-Gt
0.04 parts by weight of art-butylhydroquinone and 0.08 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite were dissolved in 85 parts by weight of methylene chloride,
A charge transport layer coating solution was prepared. This was applied onto the charge generation layer by dip coating and dried to a film thickness of 20. A charge transport layer was formed.

In this manner, the electrophotographic photoreceptor of the present invention was produced.

Examples 25 to 31 The same procedure as in Example 24 was carried out except that 2,5-di-tert-butylhydroquinone and tris(2,4-di-tert-butylphenyl)phosphite in Example 24 were changed as shown in Table-1. Each electrophotographic photoreceptor of the present invention was prepared.

Structural formula (II) Structural formula (m, ) Comparative examples 15 to 18 Examples 24, 26, and 28 except that the organic phosphite compound was removed in Examples 24, 26, and 28.30, respectively.
．． Electrophotographic photoreceptors of Comparative Examples 15 to 18 were prepared in the same manner as Example 30.

Comparative Example 19 Electrophotographic photoreceptor of Comparative Example 19 was produced in the same manner as in Example 24 except that distearylthiodipropionate was added instead of tris(2,4-di-tert-butylphenyl)phosphite. It was created.

Example 32 In the charge generation layer of Example 24, 0.03 parts by weight of 2,5-di-tert-butylhydroquinone and tris(2,4-
(di-tert-butylphenyl) phosphite 0.0
6 parts by weight, and further 2,5-T from the charge transport layer.
An electrophotographic photoreceptor was prepared in the same manner as in Example 24 except that ert-butylhydroquinone and tris(2,4-di-tert-butylphenyl) phosphite were removed.

The electrophotographic photoreceptor obtained as described above was printed on a laser printer (PC-LASER-6000; manufactured by Ricoh).
was installed and evaluated. Evaluation was performed by measuring the surface potential of an electrophotographic photoreceptor that was left in a dark place for 24 hours after the photoreceptor was prepared, and an electrophotographic photoreceptor that was stored for two months in a constant temperature bath at 60° C. after the photoreceptor was prepared. Note that the surface potential was measured by removing the developing device and attaching a surface electrometer probe to the developing position.

The results obtained are shown in Table 8.

Table 8 Example 33 An intermediate layer was formed on an aluminum drum in the same manner as in Example 24, and the charge transport layer coating solution shown in Example 24 was applied onto the intermediate layer by dip coating and dried to form a film. A charge transport layer having a thickness of 20 μm was prepared.

Next, polycarbonate resin (Panlite L-1250;
Teijin Kasei Co., Ltd. W) 4 parts by weight of 1,2-dichloroethane 20
The mixture was dissolved in a mixed solvent of 0 parts by weight and 200 parts by weight of 1,1.2-trichloroethane, and 1 part by weight of the X-type metal-free phthalocyanine shown in Example 1 was added thereto, followed by ultrasonic dispersion using an ultrasonic dispersion machine. Furthermore, this dispersion liquid is added to the structural formula (rV
3 parts by weight of a charge transport substance shown in ) was added and dissolved to prepare a coating liquid for a charge generation layer. This was spray coated on the charge transport layer and dried to form a charge generation layer having a thickness of 3 μm, thereby producing an electrophotographic photoreceptor of the present invention.

Comparative Example 20 Tris (2,4-tert
An electrophotographic photoreceptor of Comparative Example 20 was prepared in the same manner as in Example 33 except that the (butylphenyl) phosphite was omitted.

Example 34 An intermediate layer was formed on an aluminum drum in the same manner as in Example 24. 20 parts by weight of polycarbonate resin (Panlite -1300; manufactured by Konjin Kasei Co., Ltd.) was added to 250 parts by weight of 1,2-dichloroethane. Example 24
5 parts by weight of type X metal-free phthalocyanine shown in Figure 1 was added and ultrasonic dispersion was carried out using an ultrasonic dispersion machine. Further, in the dispersion, 15 parts by weight of the charge transport substance represented by the structural formula [IV], 0.08 parts by weight of 2,5-di-amylhydroquinone,
0.15 parts by weight of tris(2,4-di-tart-butylphenyl) phosphite was added and dissolved to prepare a photosensitive layer coating solution. This coating solution was applied onto the intermediate layer by a coating method and dried to form a photosensitive layer having a thickness of 16 mm, thereby producing an electrophotographic photoreceptor of the present invention.

Comparative Example 21 Tris (2,4-tert) was added from the photosensitive layer of Example 34.
An electrophotographic photoreceptor was prepared in the same manner as in Example 34 except that the (butylphenyl) phosphite was omitted.

The electrophotographic photoreceptors obtained in Examples 33 and 34 and Comparative Examples 20 and 21 were processed using a laser printer (PC-LASER-6).
Evaluation was conducted using a modified version of 000:■ (manufactured by Ricoh). The modifications include reversing the polarity of the charger and various biases, and adding a charger and a static eliminator lamp that can be used without paper passing.

The laser writing system now works. Furthermore, the developing device was removed so that a surface electrometer probe could be attached to the developing position. Evaluations were made of the surface potential of the electrophotographic photoreceptor that was left in the dark for 24 hours after the photoreceptor was made, and the surface potential of the electrophotographic photoreceptor that was stored for two months in a thermostat at 60°C after the photoreceptor was made and after 30,000 copies were made. This was done by measuring. The results obtained are shown in Table-9.

Table-9 Example 35 Alcohol-soluble polyamide (Amilan CM-8000
; Toshisha 31) 10 parts by weight, 190 parts by weight of ethyl alcohol
It was dissolved in parts by weight to prepare a coating solution for an intermediate layer. This is φ
801. The coating was applied by dip coating onto an aluminum drum having a length of φ340+am and dried at 120° C. for 10 minutes to form an intermediate layer having a thickness of 0.2 tones.

Next, 4 parts by weight of polyvinyl butyral resin (XY)IL (manufactured by Union Carbide) was dissolved in 150 parts by weight of cyclohexanone, and 10 parts by weight of the disazo pigment of exemplified compound N11 (129) was added thereto and dispersed in a ball mill for 48 hours. Further, 210 parts by weight of cyclohexanone was added, and ball mill dispersion was performed for 3 hours. This was taken out into a container and diluted with cyclohexanone while stirring so that the solid content was 1.0% by weight. The charge generation layer coating solution thus obtained was dip coated onto the intermediate layer and dried at 120°C for 10 minutes to a thickness of 0.2. 8 parts by weight of a charge transporting substance represented by the following structural formula ('I), polycarbonate resin (Panlite-1300; manufactured by Konjin Kasei Co., Ltd.), silicone oil (KF-50; Shin-Etsu Co., Ltd.), and a charge-generating layer provided thereon. (manufactured by chemical industry) 0
．． 002 parts by weight, 0.04 parts by weight of 2,5-di-tart-butylhydroquinone, Tris (2,4-di-tert-butylhydroquinone)
A charge transport layer coating solution was prepared by dissolving 0.08 parts by weight of t-butylphenyl) phosphite in 85 parts by weight of methylene chloride.

This was applied by dip coating onto the charge generation layer and dried to a film thickness of 20 μm.
A charge transport layer of m was formed. In this manner, the electrophotographic photoreceptor of the present invention was produced.

Examples 36-46 Disazo material in Example 35, 2,5-diter
t-Butylhydroquinone, tris(2,4-te
Examples 36 to 46 were prepared in the same manner as in Example 35 except that rt-butylphenyl) phosphite was changed as shown in Table IO.
Electrophotographic photoreceptors were prepared.

Table-10 Structural formula (II) Structural formula (III) Comparative examples 22 to 27 Example 35 except that the organic phosphite compound was removed in Examples 35, 37, 39, 41, 43, and 45.
, 37° 39. Comparative example 2 in the same manner as 41, 43, 45
Electrophotographic photoreceptors Nos. 2 to 27 were produced.

Comparative Example 28.29 In Example 35.41, tris(2,4-diter)
Example 35 except that distearylthiodipropionate was added instead of t-butylphenyl) phosphite.
Electrophotographic photoreceptors of Comparative Examples 28 and 29 were prepared in the same manner as in Example 41.

Example 47.48 2,5-Tart in the charge generation layer of Example 35.41
- 0.03 parts by weight of butylhydroquinone, Tris (2 parts by weight)
, 4-di-tart-butylphenyl) phosphite is added, and further 2,5-
Di-tert-butylhydroquinone, tris(2,4
An electrophotographic photoreceptor was prepared in the same manner as in Example 35.41, except that the (di-tart-butylphenyl) phosphite was removed.

F obtained by modifying the electrophotographic photoreceptor obtained as described above
It was attached to T-5510 (manufactured by WIA+) and evaluated.

The modifications included making each process capable of evaluating negatively charged photoreceptors, such as reversing the polarity of the charger and various biases. Additionally, the developing device was removed to allow a surface electrometer probe to be attached to it for potential evaluation. Evaluation was carried out by measuring the surface potential of the electrophotographic photoreceptor left in a dark place for 24 hours after preparation, and the initial and after 40,000 copies of the electrophotography photoreceptor stored in a constant temperature bath at 60°C for 2 months after preparation. Ta. The results obtained are shown in Table-11.

Table 11 Example 49 An intermediate layer was formed on an aluminum drum in the same manner as in Example 35, and the charge transport layer coating solution shown in Example 35 was applied onto the intermediate layer by dip coating and dried to form a film. A charge transport layer having a thickness of 20 mm was prepared.

Next, polycarbonate resin (Panlite L-1250;
(manufactured by Teijin Chemicals) 10 parts by weight of 1,2-dichloroethane 7
It was dissolved in a mixed solvent of 5 parts by weight and 75 parts by weight of 1,1.2-trichloroethane, and 3 parts by weight of the disazo pigment of Exemplified Compound (129) was added thereto, followed by dispersion in a ball mill for 48 hours. Further, this dispersion was added with 3 parts by weight of the charge transporting substance represented by the structural formula (1) and 150 parts by weight of 1,2-dichloroethane.
150 parts by weight of 1,1.2-trichloroethane were added, and the mixture was dispersed and dissolved in a ball mill for 24 hours to prepare a charge generation layer coating solution. This was spray coated on the charge transport layer and dried to form a charge generation layer having a thickness of 3 μl, thereby producing an electrophotographic photoreceptor.

Comparative Example 30 Tris (2,4-dite) was added from the charge transport layer of Example 49.
An electrophotographic photoreceptor of Comparative Example 30 was prepared in the same manner as in Example 49 except that rt-butylphenyl) phosphite was omitted.

Example 50 In Example 49, the disazo pigment was used as the exemplified compound Nα15
An electrophotographic photoreceptor was produced in the same manner as in Example 49 except that Example 49 was changed to Example 49.

Comparative Example 31 In Example 50, tris(2,4-
An electrophotographic photoreceptor was prepared in the same manner as in Example 50 except that di-tert-butylphenyl) phosphite was removed.

The photoconductors obtained in Examples 49 and 50 and Comparative Examples 30 and 31 had their developing sections removed, and were evaluated using FF5510 (manufactured by Ricoh) which had been modified to be equipped with a surface electrometer probe. The evaluation was performed by measuring the surface potential of an electrophotographic photoreceptor that was left in the dark for 24 hours after photoreceptor production, and of an electrophotographic photoreceptor that was stored in a constant temperature bath at 60°C for two months after photoreceptor production, both initially and after 20,000 copies were copied. It was done by doing. The results are shown in Table-12.

Table 12 From the results obtained above, by adding an organic phosphite compound to an electrophotographic photoreceptor containing a hydroquinone compound, it is possible to maintain the stability after long-term storage without deteriorating the initial photoreceptor characteristics and durability. It can be seen that an electrophotographic photoreceptor can be obtained which exhibits photoreceptor characteristics equivalent to those of the initial state and whose storage stability is greatly improved. Furthermore, these effects work similarly in the photosensitive layer coating solution, and when the same photosensitive layer coating solution contains a hydroquinone compound and an organic phosphite compound, it prevents the photosensitive layer coating solution from deteriorating and stabilizes it over a long period of time. It also has the effect of being able to obtain a coating liquid with a high temperature.

Further, as a charge generating substance, the general formula [1] to - general formula (
It can be seen that the above effects are further enhanced when the trisazo pigment or disazo pigment represented by m) is used and/or when the compound represented by the general formula [IV] is used as the charge transport material.

Claims (5)

[Claims] (1) An electrophotographic photoreceptor comprising a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support, characterized in that the photosensitive layer contains a hydroquinone compound and an organic phosphite compound. An electrophotographic photoreceptor. (2) The electrophotographic photoreceptor according to claim (1), wherein the charge generating substance is a trisazo pigment represented by the following general formula [I]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (In the formula, A represents a coupler residue having a phenolic OH group.) (3) The electrophotographic photoreceptor according to claim (1), wherein the charge generating substance is a disazo pigment represented by the following general formula [II]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [II] (In the formula, A is a coupler residue having a phenolic OH group.) (4) The electrophotographic photoreceptor according to claim (1), wherein the charge generating substance is a disazo pigment represented by the following general formula [III]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [III] (In the formula, Ar_1, Ar_2 and Ar_3 are substituted or unsubstituted carbocyclic aromatic residues or heterocyclic aromatic residues, and A is phenolic OH A coupler residue having a group,
R_1, R_2, R_3 and R_4 represent a hydrogen atom, a substituted or unsubstituted alkyl group, an aralkyl group, or an electron-withdrawing group such as a cyano group, halogen, or nitro group. ) (5) The electrophotographic photoreceptor according to claim (1), wherein the charge transport material is a compound represented by the following general formula [IV]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [IV] (In the formula, R^1 and R^4 are hydrogen atoms, alkyl groups, alkoxy groups, halogen atoms, or substituted amino groups, R^2
and R^3 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted phenyl group. ▲There are mathematical formulas, chemical formulas, tables, etc. ▼ indicates a benzene ring, naphthalene ring, anthracene ring, indole ring, or carbazole ring. n represents an integer of 0 or 1, and m represents an integer of 0, 1, 2 or 3. )