JPH0822134A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic photoreceptor having stable electrification ability even in repetitive use over a long period of time, hardly increasing residual potential and excellent in durability. CONSTITUTION:When at least an electric charge generating layer and an electric charge transferring layer are formed on an electrically conductive substrate to obtain an electrophotographic photoreceptor, the electric charge transferring layer is composed of two layers and an antioxidant is incorporated into one of the electric charge transferring layers brought into contact with the electric charge generating layer, or the electric charge generating layer is composed of two layers and an antioxidant is incorporated into one of the electric charge generating layers brought into contact with the electric charge transferring layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor using a charge generating substance and a charge transporting substance.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member (also simply referred to as a photosensitive member) having a photosensitive layer containing a charge-generating substance and a charge-transporting substance on a conductive substrate is long when it is actually used in a copying machine. It is strongly oxidized by repeated use for a long period. As a result, the charging property of the photoconductor is deteriorated and the durability is lowered. As measures against it, in JP-A-2-254466 and JP-A-1-97964, it is proposed to add an antioxidant such as tocopherol or hindered phenol to a photosensitive layer containing a charge generating substance. Proposed. However, in addition to the problem that the residual potential rises due to the addition of the antioxidant, it was not always sufficient to prevent the deterioration of the charging property.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and has a stable charging property even when it is repeatedly used for a long time in an electrophotographic copying machine, and further, the residual potential is increased. The purpose is to obtain an electrophotographic photosensitive member having less durability and excellent durability.

[0004]

According to the present invention, firstly, in an electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer provided on a conductive substrate, the charge transport layer comprises two layers. Further, there is provided an electrophotographic photosensitive member characterized by containing an antioxidant in a layer of the charge transport layer which is in contact with the charge generation layer.

Secondly, in the electrophotographic photosensitive member described in the first aspect, the thickness ratio of the charge transport layer containing an antioxidant to the charge transport layer containing no antioxidant is 1/5 or less. An electrophotographic photosensitive member characterized by the above is provided. Thirdly, the product of the film thickness ratio of the two layers of the charge transport layer of the electrophotographic photoreceptor described in the second item and the content (% by weight) of the antioxidant in the layer containing the antioxidant layer with respect to the resin is 2 There is provided an electrophotographic photosensitive member characterized by having a value of 0.0 or more and 4.0 or less. Fourthly, in an electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer provided on a conductive substrate,
Provided is an electrophotographic photosensitive member, characterized in that the charge generation layer is composed of two layers, and an antioxidant is contained in a layer of the charge generation layer which is in contact with the charge transport layer. Fifth, in the electrophotographic photosensitive member described in the fourth, the thickness ratio of the charge generation layer containing an antioxidant to the charge generation layer not containing an antioxidant is 2/5 or less. An electrophotographic photoreceptor is provided. Sixth, the product of the film thickness ratio of the two charge generation layers of the electrophotographic photosensitive member described in the fifth and the content (% by weight) of the antioxidant in the layer containing the antioxidant layer with respect to the resin is 12 Provided is an electrophotographic photosensitive member characterized by being 16 or less.

The present invention will be described in detail below. As a result of various studies on the above-mentioned problems, the present inventors have found that when an antioxidant is added to the photosensitive layer, it is stable by making the antioxidant abundant near the interface between the charge generation layer and the charge transport layer. The present invention has been accomplished by finding that the above-mentioned chargeability can be obtained.

That is, it has been found that a durable electrophotographic photoreceptor can be obtained by forming the charge transport layer into a two-layer structure and adding the antioxidant only to the layer in contact with the charge generation layer. Further, in the above structure, the film thickness ratio between the charge transport layer containing the antioxidant and the charge transport layer not containing the antioxidant and the relationship between the film thickness ratio and the content of the antioxidant are defined within a certain range. It has also been found that further excellent durability can be obtained.

On the other hand, the durability can be obtained by forming the charge generation layer into a two-layer structure and adding the antioxidant only to the layer in contact with the charge transport layer. It has been found that the durability can be further improved by defining the film thickness ratio of the layers and the relationship between the film thickness ratio and the content of the antioxidant in a specific range.

The antioxidant which can be used in the present invention includes:
Examples thereof include phosphorus-based antioxidants, sulfur-based antioxidants, phenol-based antioxidants and hindered amine-based antioxidants. The specific examples are shown below.

<Phosphorus Antioxidant> Tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, diphenylmono (tridecyl) phosphite, tetraphenyldipropylene glycol diphosphite , Tetraphenyl tetra (tridecyl) pentaerythritol tetraphosphite, 4,4
-Butylidene-bis (3-methyl-6-t-butylphenyl-di-tridecyl) phosphite, tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylenephosphite, triphenylphosphite, Aromatic phosphite esters such as tetra (tridecyl) -4,4'-isopropylidene diphenyldiphosphite, trimethyl phosphite, triethyl phosphite, tri-n-butyl phosphite, trioctyl phosphite, Triisodecyl phosphite, tridecyl phosphite, tristridecyl phosphite, trioleyl phosphite, tris (2
-Bromethyl) and other phosphite aliphatic esters, triphenylphosphine, trilauryl thiophosphite, tris (2-chloroethyl) phosphite, distearyl pentaerythritol diphosphite and the like.

Examples of sulfur-based antioxidants include the following compounds. 3,3'-thiodipropionic acid-di-n-dodecyl, 3,3'-thiodipropionic acid-di-myristyl, 3,3'-thiodipropionic acid-di-n-octadecyl, 2-mercaptobenzo Imidazole, pentaerythritol-tetrakis- (β-laurylthiopropionate), ditridecyl-3,3 '
-Thiodipropionate, dimethyl 3,3'-thiodipropionate, octadecyl thioglycolate, phenothiazine, β, β'-thiodipropionic acid, thioglycolic acid-n-butyl, ethyl thioglycolate, thioglycolic acid -2-ethylhexyl, isooctyl thioglycolate, -n-octyl thioglycolate, di-t-
Dodecyl-disulfide, n-butyl sulfide,
Di-n-amyl disulfide, n-dodecyl sulfide, n-octadecyl sulfide, p-thiocresol,

Embedded image

Further, as the phenolic antioxidant,
For example, the following compounds may be mentioned. 2,6-di-
t-butyl-p-cresol (BHT), 2,6-di-
t-butylphenol, 2,4-di-methyl-6-t-
Butylphenol, Butylhydroxyphenol, 2,
2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-t-)
Butylphenol), bisphenol A, DL-α-tocopherol, styrenated phenol, styrenated cresol, 3,5-di-t-butylhydroxybenzaldehyde, 2,6-di-t-butyl-4-hydroxymethylphenol, 2, 6-di-s-butylphenol,
2,4-di-t-butylphenol, 3,5-di-t-
Butylphenol, on-butoxyphenol, o-
t-butylphenol, m-t-butylphenol, p
-T-butylphenol, o-isobutoxyphenol, on-propoxyphenol, o-cresol,
4,6-di-t-butyl-3-methylphenol, 2,
6-dimethylphenol, 2,3,5,6-tetramethylphenol, 3- (3 ', 5'-di-t-butyl-
4'-hydroxyphenyl) propionic acid stearyl ester, 2,4,6-tri-t-butylphenol, 2,4,6-trimethylphenol, 2,4,6-
Tris (3 ', 5'-di-t-butyl-4'-hydroxybenzyl) mesitylene, 1,6-hexanediol-
Bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate], 2,2-thiobis (4
-Methyl-6-t-butylphenol), 3,5-di-
t-Butyl-4-hydroxy-benzyl phosphate-diethyl ester, 1,3,5-trimethyl-2,
4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene,

Embedded image n-octadecyl-3- (3 ', 5-di-t-butyl-
4-hydroxyphenyl) propionate, 2-t-butyl-6 (3'-t-butyl-5'-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate,
4,4'-butylidene-bis (3-methyl-6-t-butylphenol), hydroquinone, 2,5-di-t-
Butylhydroquinone, tetramethylhydroquinone, etc.

<Hindered amine antioxidant> Specific examples are shown in Table 1- (1) to Table 1- (2).

[0014]

[Table 1- (1)]

[0015]

[Table 1- (2)]

These antioxidants may be used alone or in admixture of two or more.

Next, the photosensitive layer will be described. First, the charge generation layer is a layer containing a charge generation material as a main material, and a binder resin may be used if necessary.

As the binder resin, polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide and the like are used. To be

As the charge generating substance, for example, CI Pigment Blue 25 [Color Index (CI) 2
1180], CI Pigment Red 41 (CI 2
1200), CI Acid Red 52 (CI 45
100), CI Basic Red 3 (CI 452
10), further, a phthalocyanine-based pigment having a polyfin skeleton, an azurenium salt pigment, a squalic salt pigment,
Azo pigments having a carbazole skeleton (JP-A-53-95)
033), azo pigments having a stilbene skeleton (see JP-A-53-138229), and azo pigments having a triphenylamine skeleton (JP-A-53-1325).
47), azo pigments having a dibenzothiophene skeleton (see JP-A-54-21728), and azo pigments having an oxadiazole skeleton (JP-A-54-127).
42), an azo pigment having a fluorenone skeleton (see JP-A-54-22834), an azo pigment having a bisstilbene skeleton (see JP-A-54-17733), and a distyryl oxadiazole skeleton. Azo pigments (see JP-A-54-2129) and azo pigments having a distyrylcarbazole skeleton (JP-A-54-1).
7734), and trisazo pigments having a carbazole skeleton (JP-A-57-195767 and 57).
No. 195768), and phthalocyanine pigments such as CI Pigment Blue 16 (CI 74100), CI Eye Brown 5 (CI 734).
10), organic pigments such as indigo-based pigments such as CI Avatar Dye (CI 73030), perylene-based pigments such as Argos Scarlet B (manufactured by Violet), and Indense Scarlet R (manufactured by Bayer) can be used. .

Among these charge generating substances, azo pigments are particularly preferable, and among the azo pigments, the disazo pigments and trisazo pigments shown below are most preferable. Specific examples of the azo pigment are shown below. (Below margin)

[0021]

[Table 2- (1)]

[0022]

[Table 2- (2)]

[0023]

[Table 3- (1)]

[0024]

[Table 3- (2)]

[0025]

[Table 3- (3)]

[0026]

[Table 4- (1)]

[0027]

[Table 4- (2)]

[0028]

[Table 4- (3)]

These charge generating substances may be used alone or in combination of two or more. The binder resin is appropriately used in an amount of 0 to 100 parts by weight, preferably 0 to 50 parts by weight, based on 100 parts by weight of the charge generating substance. The charge generation layer is formed by dispersing the charge generation substance together with a binder resin, if necessary, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, etc. by a ball mill, attritor, sand mill, etc., and diluting the dispersion liquid appropriately. It can be formed by

Next, the charge-transporting layer comprises a charge-transporting substance and a binder resin which is optionally used. These substances are dissolved or decomposed in a suitable solvent and applied to form the charge-transporting layer. be able to. The charge transport material includes a hole transport material and an electron transport material.

As the hole-transporting substance, poly-N-vinylcarbazole and its derivative, poly-γ-carbazolylethylglutamate and its derivative, pyrene-formaldehyde condensate and its derivative, polyvinylpyrene, polyvinylphenanthrene and oxazole derivative. ,
Oxadiazole derivative, imidazole derivative, triphenylamine derivative, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazone, α Electron-donating substances such as phenylstilbene derivatives.

Examples of the electron-transporting substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-. Fluorenone, 2,4,5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone, 2,4,8-
Examples thereof include electron-accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one and 1,3,7-trinitrodibenzothiophenone-5,5-dioxide.

These charge transport materials may be used alone or in admixture of two or more. Further, as the binder resin used in the present invention as necessary, polystyrene, styrene-acrylonitrile copolymer, styrene-
Butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, Ethyl cellulose resin,
Examples thereof include thermoplastic or thermosetting resins such as polyvinyl butyral, polyvinyl formal, polyvinyltoluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

As the solvent, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride or the like is used. Further, in the present invention, a plasticizer or a leveling agent may be added to the charge transport layer.

As the plasticizer, those which have been used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount thereof is preferably about 0 to 30% by weight based on the binder resin. is there. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil are used, and the amount thereof is preferably 0 to 1% by weight based on the binder resin.

In the present invention, the charge transport layer composed of these substances has a two-layer structure, or the charge generation layer has a two-layer structure. In the former structure, only the layer in contact with the charge generation layer is In the latter configuration, the antioxidant is added only to the layer in contact with the charge transport layer. This creates a state in which a large amount of the antioxidant is present in the vicinity of the interface between the charge generation layer and the charge transport layer, so that a photoreceptor is obtained in which both chargeability deterioration and increase in residual potential are small.

Further, among the two charge transport layers in the former structure, the charge transport is performed so that the ratio of the thickness of the layer containing the antioxidant to the layer not containing the antioxidant is 1/5 or less. A layer is formed, or the thickness ratio of the layer containing an antioxidant to the layer not containing an antioxidant in the two-layer charge generation layer in the latter structure is 2/5 or less. When the charge transport layer is formed, the above-mentioned effects are further enhanced. If this film thickness ratio is larger than 1/5 in the former structure and larger than 2/5 in the latter structure, the proportion of the antioxidant present near the interface between the charge transport layer and the charge generation layer is small. Therefore, the effect of the present invention is reduced.

Furthermore, in the former constitution, the product of the film thickness ratio of the two layers of the charge transport layer and the content (wt%) of the antioxidant in the charge transport layer containing the antioxidant with respect to the resin is 2.0. In the latter configuration, the product of the film thickness ratio of the two layers of the charge generation layer and the content (% by weight) of the antioxidant in the charge generation layer containing the antioxidant with respect to the resin is 12 or more. If it is 16 or more, more excellent effects can be obtained.

That is, this product is 2.0 in the former configuration.
When the ratio is smaller, the proportion of the antioxidant in the entire charge transport layer is smaller, and in the latter configuration, when the product is smaller than 12, the proportion of the antioxidant in the entire charge generation layer is small. If the product is larger than 4.0 in the former structure and the product is larger than 16 in the latter structure, the proportion of the antioxidant is large, and the residual potential of the antioxidant is large. The increase is rather large.

When the two charge transport layers are provided in the present invention, the total thickness of the two layers is 5 to 1
It is suitable to be 00 μm, and preferably 10 to 50 μm. When the two charge generation layers are provided in the present invention, the total thickness of the two layers is appropriately 0.1 to 5 μm, preferably 0.1 to 2 μm.
If it is μm, it is preferable.

As the coating method of the charge transport layer and the charge generating layer in the present invention, any coating method such as dip coating method, spray coating method and bead coating method may be used.
Among them, the spray coating method is preferable. This is because when the second charge transport layer is applied on the first charge transport layer, the first charge transport layer may dissolve into the second charge transport layer coating liquid except by the spray coating method. Is. Similarly, when coating the second charge generation layer on the first charge generation layer,
This is because the first charge generating layer may melt into the second charge generating layer coating liquid other than the spray coating method.

The conductive substrate in the present invention has conductivity with a volume resistance of 10 ¹⁶ Ωcm or less, for example,
Aluminum, nickel, chrome, nichrome, copper, silver,
Metals such as gold and platinum, metal oxides such as tin oxide and indium oxide, which are coated on film or cylindrical plastic, paper, etc. by vapor deposition or sputtering, or plates of aluminum, aluminum alloy, nickel, stainless steel, etc. And D. I, I. I,
It is possible to use a tube or the like which is made into a raw tube by a method such as extrusion or drawing and then surface-treated by cutting, superfinishing, polishing or the like.

The layer structure of the electrophotographic photosensitive member of the present invention is not limited to the structure of conductive substrate / charge generating layer / charge transporting layer, but may be a conductive substrate / charge transporting layer / charge generating layer. The order of stacking the generation layer and the charge transport layer may be reversed. An intermediate layer may be provided between the conductive substrate and the photosensitive layer, and a protective layer may be provided on the surface of the photosensitive layer.

[0044]

EXAMPLES The present invention will be described in more detail with reference to examples.

[Example 1] Pigment No. 10 parts by weight of the disazo pigment of 1 were mixed with 150 parts by weight of cyclohexanone,
Disperse with a ball mill for 120 hours. To this dispersion was added a solution prepared by dissolving 4 parts by weight of butyral resin (XYHL manufactured by Union Carbide Co., Ltd.) in 150 parts by weight of cyclohexanone, and then diluted with cyclohexanone so that the solid content was 1.0%. The charge generation layer coating solution thus obtained was used to prepare
It was applied by dipping onto an aluminum drum having a length of 0 mm and a length of 340 mm and dried at 120 ° C. for 10 minutes to form a charge generation layer having a film thickness of 0.2 μm. Next, 10 parts by weight of a polycarbonate resin (Panlite K-1400 manufactured by Teijin Chemicals Co., Ltd.) was dissolved in 85 parts by weight of tetrahydrofuran, and 9 parts by weight of a charge transport substance represented by the following structural formula (a) was dissolved therein. Further, 2 parts by weight of a phenolic antioxidant 2,6-di-t-butyl-p-cresol (BHT) was added to this solution to obtain a charge transport layer coating solution (I). This was spray-coated on the charge generation layer and dried at 100 ° C. for 20 minutes to form a first charge transport layer having a film thickness of 4 μm. Next, in the charge transport layer coating liquid (I), a liquid was prepared in the same manner except that BHT was not added to obtain a charge transport layer coating liquid (II). This was spray-coated on the first charge transport layer and dried at 130 ° C. for 20 minutes to provide a second charge transport layer having a film thickness of 20 μm, and the electrophotographic photosensitive member of the present invention was produced.

Embedded image

Example 2 A photoconductor was prepared in the same manner as in Example 1 except that the amount of BHT added was changed to 1 part by weight.

Example 3 A photoconductor was prepared in the same manner as in Example 1 except that the thickness of the first charge transport layer was changed to 3 μm.

Example 4 A photoconductor was prepared in the same manner as in Example 1 except that the amount of BHT added was changed to 4 parts by weight and the thickness of the first charge transport layer was changed to 2 μm. It was made.

Example 5 A photoconductor was obtained in the same manner as in Example 1, except that the phosphorus antioxidant tristearyl phosphite (TSP) was used in place of BHT.

Example 6 Photosensitization was carried out in the same manner as in Example 1 except that the sulfur antioxidant 3,3'-thiodipropionate-di-n-dodecyl was used in place of BHT. The body was made.

Example 7 A photoconductor was prepared in the same manner as in Example 1 except that the amount of BHT added was 1 part by weight and the thickness of the first charge transport layer was 5 μm. It was made.

Example 8 A photoconductor was prepared in the same manner as in Example 1 except that the amount of BHT added was 2.5 parts by weight.

Example 9 A photoreceptor was prepared in the same manner as in Example 1 except that the amount of BHT added was 1 part by weight and the thickness of the first charge transport layer was 3 μm. It was made.

Comparative Example 1 Photosensitization was carried out in the same manner as in Example 1 except that only one charge transport layer was provided by using the charge transport layer coating liquid (I) and the film thickness was 24 μm. The body was made.

Comparative Example 2 In Example 1, the charge transport layer coating liquid (II) was used to form a first charge transport layer having a thickness of 20 μm, and then the charge transport layer coating liquid (I) was used. Film thickness 4
A photoconductor was prepared in the same manner as in Example 1 except that the second charge transport layer having a thickness of μm was provided.

[Example 10] Pigment No. 25 parts by weight of the disazo pigment of 1 was mixed with 300 parts by weight of cyclohexanone, and dispersed by a ball mill for 120 hours. Butyral resin (XYHL manufactured by Union Carbide Co.) 10 was added to this dispersion.
A solution prepared by dissolving 300 parts by weight of cyclohexanone in 300 parts by weight was added, and then diluted with cyclohexanone so that the solid content was 1.0% to obtain a charge generation layer coating solution (I). This is spray-coated on an aluminum drum having a diameter of 80 mm and a length of 340 mm, and dried at 120 ° C. for 10 minutes to obtain a film thickness of 1.0
A first charge generation layer of μm was provided. Next, a solution was prepared in the same manner as the charge generation layer coating solution (I), and 4 parts by weight of a phenolic antioxidant 2,6-di-t-butyl-p-cresol (BHT) was added to the solution. Then, a charge transport layer coating solution (II) was obtained. This was spray-coated on the charge generation layer and dried at 120 ° C. for 10 minutes to form a second charge generation layer having a thickness of 0.4 μm. Next, 10 parts by weight of a polycarbonate resin (Panlite K-1400 manufactured by Teijin Chemicals Ltd.) was dissolved in 85 parts by weight of tetrahydrofuran, and 9 parts by weight of the charge transport material having the structural formula (a) was dissolved therein. The charge transport layer coating solution thus obtained is spray coated on the second charge generation layer and dried at 130 ° C. for 20 minutes to give a film thickness of 24 μm.
A charge transport layer of m was provided to prepare an electrophotographic photoreceptor of the present invention.

[Embodiment 11] In the tenth embodiment, BH
A photoconductor was produced in the same manner as in Example 10 except that the addition amount of T was 3 parts by weight.

[Embodiment 12] Embodiment 1 is different from Embodiment 10 except that the film thickness of the second charge generation layer is 0.3 μm.
A photoconductor was prepared in the same manner as in No. 0.

[Embodiment 13] In the tenth embodiment, BH
A photoconductor was prepared in the same manner as in Example 10 except that the addition amount of T was 8 parts by weight and the thickness of the charge generation layer was 0.2 μm.

[Embodiment 14] In the tenth embodiment, BH
A photoconductor was prepared in the same manner as in Example 10 except that the phosphorus antioxidant tristearyl phosphite (TSP) was used in place of T.

[Embodiment 15] In Embodiment 10, BH
Example 10 except that the sulfur antioxidant 3,3′-thiodipropionate-di-n-dodecyl was used in place of T.
A photoconductor was prepared in the same manner as in.

[Example 16] In Example 10, BH
A photoconductor was produced in the same manner as in Example 10 except that the addition amount of T was 3 parts by weight and the thickness of the second charge generation layer was 0.5 μm.

[Embodiment 17] In the tenth embodiment, BH
A photoconductor was produced in the same manner as in Example 10 except that the addition amount of T was 4.5 parts by weight.

[Embodiment 18] In the tenth embodiment, BH
A photoconductor was produced in the same manner as in Example 10 except that the addition amount of T was 2.5 parts by weight.

[Comparative Example 3] In Example 10, only one charge generation layer was provided using the charge generation layer coating liquid (II).
A photoconductor was prepared in the same manner as in Example 10 except that the film thickness was 1.4 μm.

Comparative Example 4 In Example 10, the charge transport layer coating liquid (II) was used to form a first charge generation layer having a thickness of 0.4 μm, and then the charge generation layer coating liquid (I) was added. A photoconductor was prepared in the same manner as in Example 10 except that the second charge generation layer having a thickness of 1.0 μm was provided.

The above photoconductors were mounted in an electrophotographic copying machine (FT-3300, manufactured by Ricoh Co., Ltd.), and the surface potential (VD) of the non-exposed portion at the initial stage and after copying 20,000 sheets,
The exposed surface potential (VL) and the residual potential (VR) were evaluated. The potential was evaluated by removing the developing device and attaching a surface electrometer thereto. The results are shown in Table 5 and Table 6.
Shown in

[0068]

[Table 5]

[0069]

[Table 6]

[0070]

As described above, the charge transport layer is composed of two layers, and the antioxidant is contained only in the layer in contact with the charge generation layer, or the charge generation layer is composed of two layers. According to the electrophotographic photosensitive member of the present invention in which the antioxidant is contained only in the layer in contact with, the chargeability is not lowered and the residual potential is not increased even when it is repeatedly used for a long period of time. Further, in the former constitution, the film thickness ratio between the layer containing the antioxidant and the layer not containing the antioxidant is 1/5.
The following are more effective than the ones larger than 1/5. Similarly, in the latter constitution, the film thickness ratio of the layer containing the antioxidant to the layer not containing the antioxidant is 2/5.
The following are more effective than the ones larger than 2/5. Furthermore, when the product of the film thickness ratio and the content of the antioxidant is 2.0 or more and 4.0 or less in the former configuration, even if the film thickness ratio is ⅕ or less, it falls outside the range of the product. As compared with the above, the deterioration of the charging property and the increase of the residual potential are less, and excellent durability can be obtained. Similarly, in the latter configuration, the product of the film thickness ratio and the content of the antioxidant is 1
When it is 2 or more and 16 or less, even if the film thickness ratio is 2/5 or less, the deterioration of the charging property and the increase of the residual potential are smaller and excellent durability can be obtained as compared with the case where the product ratio is out of the range. .

[Brief description of drawings]

1A to 1D are cross-sectional views each showing an example of a typical layer structure in an electrophotographic photosensitive member of the present invention.

2A to 2D are cross-sectional views each showing an example of a typical layer structure in the electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive substrate 2 Charge generating layer containing no antioxidant 2a Charge generating layer containing antioxidant 3 Charge transporting layer containing no antioxidant 3a Charge transporting layer containing antioxidant 4 Intermediate layer 5 Protective layer

Claims (6)

[Claims] 1. An electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer provided on a conductive substrate, wherein the charge transport layer comprises two layers, and a charge generation layer of the charge transport layer is included. An electrophotographic photosensitive member characterized in that a layer on the side in contact with it contains an antioxidant. 2. The charge transport layer has a thickness ratio of 1 between the layer containing an antioxidant and the layer not containing an antioxidant.
The electrophotographic photoconductor according to claim 1, wherein the electrophotographic photoconductor is / 5 or less. 3. The product of the film thickness ratio and the content (% by weight) of the antioxidant in the layer containing the antioxidant with respect to the resin is 2.0 or more and 4.0 or less. The electrophotographic photosensitive member according to claim 2. 4. An electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer provided on a conductive substrate, wherein the charge generation layer comprises two layers, and a charge transport layer of the charge generation layer is included. An electrophotographic photosensitive member characterized in that a layer on the side in contact with it contains an antioxidant. 5. The charge generation layer has a thickness ratio of 2 between a layer containing an antioxidant and a layer not containing an antioxidant.
5. The electrophotographic photosensitive member according to claim 4, which is / 5 or less. 6. The product of the film thickness ratio and the content (% by weight) of the antioxidant in the layer containing the antioxidant with respect to the resin is 12 or more and 16 or less.
The electrophotographic photosensitive member described.