JPH0580572A - Electrophotographic sensitive material - Google Patents

Abstract

PURPOSE:To improve printing resistance against repeated use and to suppress increase in residual potential after repetition of electrification and exposure by providing an intermediate layer containing a specified proportion range of a white pigment and a binder between a base body and a photoconductive layer and further providing a base coating layer between the intermediate layer and the base body. CONSTITUTION:This electrophotographic sensitive body has a photoconductive layer provided on a conductive base body. An intermediate layer is provided between the conductive base body and the photoconductive layer. This intermediate layer essentially consists of a white pigment and a binder resin with 1/1-3/1 volume ratio of the white pigment to the binder resin. Further, a base coating layer comprising a binder resin is provided between the intermediate layer and the conductive base body. Thereby, adhesion property between the base body and the intermediate layer is improved, which improves printing resistance against repeated use and suppresses increase in residual potential after repetition of electrification and exposure.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor,
More specifically, it relates to improvement of an electrophotographic photoreceptor having an intermediate layer provided between a substrate and a photoconductive layer.

[0002]

2. Description of the Related Art Conventionally, inorganic photoconductive substances such as selenium and selenium alloys, zinc oxide, and cadmium sulfide have been mainly used as photosensitive materials for electrophotographic photoreceptors. On the other hand, recently, a material using an organic photosensitive material, which has advantages of low cost, productivity and no pollution, has begun to be used. Polyvinylcarbazole (P
VK) represented by photoconductive resin, PVK-TNF
(2,4,7-trinitrofluorenone), a charge-transfer complex type, a phthalocyanine-binder, a pigment-dispersed type, and a function-separated type photoconductor in which a charge-generating substance and a charge-transporting substance are used in combination. Is known, and in particular, a function-separated type photoconductor is drawing attention.

When such a function-separated high-sensitivity photoconductor is applied to the Carlson process, the chargeability is low, the charge retention is poor (dark decay is large), and the characteristics are deteriorated by repeated use. Large, uneven density on the image,
In the case of fog and reversal development, there is a drawback that background stains occur. In order to improve the electrical characteristics of such a photoreceptor, it is considered effective to provide an intermediate layer between the substrate and the photosensitive layer.

Generally, the purpose of providing such an intermediate layer is to improve adhesion, improve coatability of the photosensitive layer, protect the substrate, cover defects on the substrate, protect the photosensitive layer against electrical breakdown, and remove the substrate. Examples include improvement of charge injection property to the photosensitive layer.

For example, Japanese Patent Laid-Open Nos. 47-6341 and 48-35
44 and 48-12034, a cellulose nitrate resin intermediate layer is disclosed in JP-A-48-47344, 52-2563.
8, 58-30757, 58-63945, 58-953
51, 58-98739 and 60-66258, nylon resin intermediate layers; JP-A-49-69332 and 52-10138, maleic acid resin intermediate layers; and JP-A-58-105155. Each polyvinyl alcohol resin intermediate layer is disclosed.

However, since the intermediate layer of these resin single layers has a high electric resistance, a residual potential is generated and a background stain occurs in the image. Especially, under low temperature and low humidity, the electric resistance of the intermediate layer becomes particularly high, so that there is a drawback that if a thin film is used to reduce the residual potential, the charging property becomes insufficient.

Therefore, an intermediate layer has been proposed in which various conductive additives are contained in a resin in order to control the electric resistance of the intermediate layer. For example, in JP-A-51-65942, an intermediate layer in which a carbon or chalcogen-based substance is dispersed in a curable resin is used, and in JP-A-52-82238, a quaternary ammonium salt is added to use an isocyanate-based curing agent. The heat-polymer intermediate layer is the one described in JP-A-55-1130451, and the resin intermediate layer to which a resistance adjusting agent is added is JP-A-58-585.
No. 56 discloses a resin intermediate layer in which an oxide of aluminum or tin is dispersed, and JP-A No. 58-93062 discloses a resin intermediate layer in which an organic metal compound is added.
No. 3,60-97363 and 60-111255, a resin intermediate layer in which conductive particles are dispersed is disclosed in JP-A-59-17.
No. 557, a layer in which magnetite is dispersed in a resin, and further, in JP-A-59-84257, 59-93453 and 60-32054, a resin intermediate layer in which TiO ₂ and SnO ₂ powder are dispersed, JP-A-64-68762, 64
-68763, 64-73352, 64-73353,
Japanese Patent Application Laid-Open Nos. 1-118849 and 1-118848 disclose intermediate layers of resin in which powders of borides, nitrides, fluorides and oxides such as calcium, magnesium and aluminum are dispersed.

However, in the intermediate layer in which the filler is dispersed as described above, it is necessary to reduce the amount of resin in order to improve the electrostatic characteristics of the electrophotographic photoreceptor. However, when the amount of the resin in the intermediate layer is low, the adhesiveness to the substrate is deteriorated, and peeling between the substrate and the intermediate layer is likely to occur due to repeated use. In particular, it has a drawback that it becomes remarkable when a flexible substrate is used.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photoreceptor having excellent printing durability in repeated use and high sensitivity, and having a small residual potential even after repeated charging and exposure. To aim.

[0010]

According to the present invention, in an electrophotographic photoreceptor having a photoconductive layer provided on a conductive substrate, a white pigment and a binder resin are provided between the conductive substrate and the photoconductive layer. Is provided as a main component, and a white pigment and a binder resin are used in an amount of 1/1 to 3/1 by volume, and an intermediate layer is provided, and a binder is provided between the conductive substrate and the intermediate layer. Provided is an electrophotographic photoreceptor, which is provided with an undercoat layer made of a resin agent.

The present inventors have earnestly studied an electrophotographic photoreceptor having excellent printing durability in repeated use and high sensitivity, and having a small residual potential even after repeated charging and exposure. An intermediate layer containing a white pigment and a binder resin as main components between the substrate and the photoconductive layer, and using the white pigment and the binder resin in a volume ratio of 1/1 to 3/1. In addition to the above, it was found that the above object can be achieved by providing an undercoat layer made of a binder resin between the conductive substrate and the intermediate layer, and completed the present invention.

The present invention will be described in detail below. As the conductive substrate, a metal such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, and stainless steel, a metal oxide such as tin oxide, indium oxide, nickel oxide, and aluminum oxide is deposited or sputtered into a film. Or cylindrical plastic (polyethylene terephthalate, polybutylene terephthalate, phenol resin, polypropylene, nylon, polystyrene, etc.)
Alternatively, a sheet coated with paper or the like, or a plate made of aluminum, an aluminum alloy, nickel, stainless steel or the like and D. I. , I. I. , Tubes that have been formed into a raw tube by a method such as extrusion or drawing, and then surface-treated by cutting, superfinishing, polishing, etc., or those made into a film or cylinder by a method such as electroplating, or conductive powder It is possible to use a film-shaped or cylindrical-shaped body obtained by dispersing and molding a body in plastic.

The undercoat layer is composed of a single binder resin layer, and an appropriate layer can be used. Examples of such a binder resin include thermoplastic resins such as polyamide, polyester, and vinyl chloride-vinyl acetate copolymer, and thermosetting resins such as active hydrogen (--OH group, --NH ₂ group, --NH group, etc.). A thermosetting resin obtained by thermally polymerizing a compound containing a plurality of hydrogen) and a compound containing a plurality of isocyanate groups and / or a compound containing a plurality of epoxy groups can also be used. In this case, as the compound containing a plurality of active hydrogens, for example, polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester, polyethylene glycol, polypropylene glycol, polybutylene glycol, acryl containing active hydrogen such as hydroxyethylmethacrylate group. Examples include resin series.
Examples of the compound having a plurality of isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate and the like and prepolymers thereof, and examples of the compound having a plurality of epoxy groups include bisphenol A type epoxy resin. can give.

Further, a thermosetting resin obtained by thermally polymerizing an oil-free alkyd resin and an amino resin, such as butylated melamine resin, and also a resin having an unsaturated bond such as polyurethane having an unsaturated bond or unsaturated polyester. A photocurable resin such as a combination of a thioxanthone compound and a photopolymerization initiator such as methylbenzyl formate can also be used as the binder resin.

The undercoat layer may have conductivity by adding a conductive polymer or an ionic resin to the above resin. Alternatively, an acceptor resin or the like may be added to have a function of suppressing charge injection from the substrate.

The thickness of the undercoat layer is 0.01 to 1 μm.
m, preferably about 0.03 to 3 μm. When the undercoat layer becomes thick, the residual potential increases remarkably at low temperature and low humidity due to repeated charging and exposure, and when the film thickness is too thin, the effect of adhesiveness disappears, and the undercoat layer has conductivity. If it is, the thickness is about 0.01 to 100 μm.

If necessary, chemicals, solvents, additives, curing accelerators, etc. necessary for curing (crosslinking) are added to the undercoat layer, and blade coating, dip coating, spraying are carried out by a conventional method. It is formed on the substrate by a coat, beat coat, nozzle coat method or the like. After coating, it is dried or heated and cured by light or the like to be dried or cured.

The intermediate layer is composed of at least a white pigment and a binder resin, and the use ratio of the white pigment and the binder is regulated to 1/1 to 3/1 in volume ratio. If the volume ratio of the white pigment to the binder resin is less than 1/1, the residual potential increases and the sensitivity decreases remarkably after repeated use. If the volume ratio exceeds 3/1, air bubbles form in the photoconductive layer. May occur, which lowers the chargeability of the photoconductive layer, resulting in deterioration of the quality of the copied image.

Examples of the white pigment used in the intermediate layer include titanium oxide, calcium fluoride, calcium oxide, silicon oxide, magnesium oxide, zirconium oxide, aluminum oxide, etc., which may be used alone or in combination of two or more. be able to.

Any appropriate binder resin can be used, and the same binder resin as that used for the undercoat layer can be used. However, it is necessary to select so as not to be affected by the photosensitive layer. The thickness of the intermediate layer is 0.3 to 10 μm, preferably 0.5 to 5 μm. If the film thickness is less than 0.3 μm, the effect expression is small, and if it exceeds 10 μm, residual potential is accumulated, which is not desirable.

The white pigment is dispersed together with a solvent and a binder resin by a conventional method, for example, by a ball mill, a sand mill, an attriler, etc., and if necessary, a chemical agent, a solvent, an additive and a curing accelerator necessary for curing (crosslinking). An agent or the like is added, and the composition is formed on the substrate by a conventional method such as blade coating, dip coating, spray coating, beat coating, or nozzle coating. After coating, it is dried or heated and cured by light or the like to be dried or cured.

As the photoconductive layer used in the present invention,
(1) A compound in which a charge transfer complex is formed by a combination of an electron-donating compound and an electron-accepting compound (USP34842)
37), (2) sensitized by adding a dye to an organic photoconductor (described in JP-B-48-25658),
(3) Pigment dispersed in a hole or electron active matrix (JP-A 47-30328, JP-A 47-1)
No. 8545), and (4) a functionally separated charge generation layer and charge transport layer (JP-A-49-1055).
No. 37), (5) containing a eutectic complex composed of a dye and a resin as a main component (described in JP-A-47-10785), and (6) an organic pigment or an inorganic charge in the charge transfer complex. Those to which a generating material is added (JP-A-49-916)
It may be formed of any conventionally known organic photoconductor such as the one described in Japanese Patent Laid-Open No. 48).

However, among these, the laminated type photoreceptor of the type (4) is particularly advantageous because it has high sensitivity and various materials can be selected according to the function.

Next, the charge generation layer will be described. The charge generating layer is a layer containing a charge generating substance 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.

As the charge generating substance, for example, CI Pigment Blue 25 [Color Index (CI) 21
180], CI Pigment Red 41 (CI 21
200), CI Acid Red 52 (CI 4510
0), CI Basic Red 3 (CI 4521
0), and further, a phthalocyanine-based pigment having a porphyrin skeleton, an azurenium salt pigment, a squalic salt pigment,
Azo pigments having a carbazole skeleton (JP-A-53-95)
No. 033), an azo pigment having a stilstilbene skeleton (described in JP-A-53-138229), and an azo pigment having a triphenylamine skeleton (JP-A-53-53).
No. 132547), an azo pigment having a dibenzothiophene skeleton (described in JP-A No. 54-21728), an azo pigment having an oxadiazole skeleton (JP-A No.
4-12742), an azo pigment having a fluorenone skeleton (described in JP-A-54-22834),
Azo pigments having a bisstilbene skeleton (JP-A-54-1)
7733), an azo pigment having a distyryl oxadiazole skeleton (described in JP-A No. 54-2129), an azo pigment having a distyryl carbazole skeleton.
(Described in JP-A-54-17734), triazo pigment having a carbazole skeleton (JP-A-57-195767).
No. 57-195768, etc.) and CI Pigment Blue 16 (CI 7410).
0) and other phthalocyanine-based pigments, CIVAT BROWN 5 (CI 73410), CIVAT Die (CI
73030) and other indigo pigments, Argos Scarlet B (manufactured by Violet), Induslen Scarlet R
Organic pigments such as perylene pigments (such as Bayer Co.) 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. Table 1 shows specific examples of the azo pigment.

[0027]

[Table 1- (1)]

[0028]

[Table 1- (2)]

[0029]

[Table 1- (3)]

[0030]

[Table 1- (4)]

[0031]

[Table 1- (5)]

[0032]

[Table 1- (6)]

[0033]

[Table 1- (7)]

[0034]

[Table 1- (8)]

[0035]

[Table 1- (9)]

[0036]

[Table 1- (10)]

[0037]

[Table 1- (11)]

[0038]

[Table 1- (12)]

[0039]

[Table 1- (13)]

[0040]

[Table 1- (14)]

[0041]

[Table 1- (15)]

These charge generating substances may be used alone or
Used 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.

In the charge generation layer, the charge generation substance is dispersed together with a binder resin if necessary using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, etc. by a ball mill, an attritor, a sand mill or the like, and the dispersion is appropriately diluted. It can be formed by applying. The coating can be performed by using a dip coating method, a spray coating method, a bead coating method, or the like. The thickness of the charge generation layer is appropriately 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer comprises a charge transport material and a binder resin used as necessary. The charge transporting layer can be formed by dissolving or dispersing the above substances in a suitable solvent and coating and drying them. 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, oxazole derivative, oxadiazole derivative, imidazole derivative, triphenylamine derivative, 9- (p-diethylaminostyryl) anthracene, 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyra Examples thereof include electron-donating substances such as zoline, phenylhydrazones, and α-phenylstilbene derivatives.

Examples of the electron transporting substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-trinitro-9-fluorenone and 2,4,5,7-tetranitro-9-fluorenone. , 2,4,5,7
-Tetranitroxanthone, 2,4,8-Trinitrothioxanthone, 2,6,8-Trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-Trinitrodibenzothiophenone An electron-accepting substance such as -5,5-dioxide can be used. These charge transport substances may be used alone or in combination of two or more.

Further, as the binder resin used in the present invention as required, 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, polyvinyl butyral, polyvinyl formal, polyvinyl toluene,
Poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin,
Examples include thermoplastic or thermosetting resins such as phenolic resins and alkyd resins. As the solvent, tetrahydrofuran, dioxane, toluene, monochlorobenzene,
Dichloroethane, methylene chloride, etc. are used.

A suitable thickness of the charge transport layer is about 5 to 100 μm. Further, in the present invention, a plasticizer or a leveling agent may be added to the charge transport layer. As the plasticizer, those used as a plasticizer for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount thereof is 0 to 30% by weight with respect to the binder resin.
The degree is appropriate. Silicone oils such as dimethyl silicone oil and methylphenyl silicone oil are used as the leveling agent, and the amount of the oil used is appropriately about 0 to 1% by weight based on the binder resin. In the present invention, it is possible to further provide an insulating layer or a protective layer on the photosensitive layer.

[0049]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Example 1 Copolyamide resin (trade name: Alamin CM-800
No. 0, manufactured by Toray Industries, Inc., 150 parts was dissolved in 3395 parts of methanol and 1455 parts of butanol to obtain an undercoat layer coating solution. This undercoat layer coating solution is dip-coated on a nickel cylinder having a diameter of 146 mm, a length of 340 mm and a thickness of about 30 μm, which is prepared by electroplating. An undercoat layer was formed.

Next, in a hard glass pot of 15 cmφ, 1/2 volume of 1 cm alumina sintered balls, titanium oxide (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) fine powder 414 gr, and oil having a solid content concentration of 50% by weight. Free alkyd resin (Beckolite M6401-50, Dainippon Ink and Chemicals, Inc.)
(Produced by Mitsui Chemicals Co., Ltd.) and 83 g of butylated melamine resin (Super Beckamine G821-60, manufactured by Dainippon Ink and Chemicals, Inc.) having a solid content of 60% by weight were added for 48 hours and methyl ethyl ketone 345 gr, followed by milling for 24 hours. Was diluted with to obtain a 50% by weight intermediate layer coating solution. Five pots of this were prepared. In addition,
Since the specific gravity of the resin used in the intermediate layer is 1.4 and the specific gravity of titanium oxide is 4.2, the titanium oxide / resin in the intermediate layer has a volume ratio of 2/1. The intermediate layer coating solution was applied onto the undercoat layer by dip coating and dried and cured at 130 ° C. for 20 minutes to form an intermediate layer having a thickness of 2 μm.

Next, the disazo pigment of the following structural formula 1 was used.
8 copies

[Chemical 1] 1.38 parts of polyvinyl butyral (trade name: XYHL, Union Carbide Plastic Co., Ltd.) and 276 parts of methyl ethyl ketone were dispersed in a ball mill for 120 hours, and 414 parts of cyclohexanone and 690 parts of methyl ethyl ketone were added to the dispersion liquid as a diluent. It was used as the coating liquid for the charge generation layer. Five pots of this were prepared. This coating solution was applied onto the above intermediate layer by dip coating and dried by heating at 120 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.3 μm.

450 parts of the compound of the following structural formula 2 on the charge generation layer

[Chemical 2] Polycarbonate resin (Panlite C-1400, Teijin Chemical Co., Ltd.) 500 parts Silicone oil (KF-50, Shin-Etsu Silicone Co., Ltd.) 0.1 part Methylene chloride 4325 parts Dip coating of charge transport layer coating liquid Worked at 130 ℃, 2
The charge transport layer having a film thickness of 20 μm was formed by drying for 0 minutes to prepare an electrophotographic photosensitive member of Example 1.

Example 2 150 parts of a polycarbonate resin (Panlite K-1300, manufactured by Teijin Chemical Co., Ltd.) was dissolved in 4850 parts of methylene chloride to prepare an undercoat layer coating solution. This undercoat layer coating liquid was vacuum-deposited with Al to have a diameter of 146 mm and a length of 340 mm.
It is dip coated on a biaxially stretched polyester cylinder having a thickness of about 75 μm, heated and dried at 110 ° C. for 10 minutes to give a thickness of 0.1
An undercoat layer of 1 μm was formed. Next, in a hard glass pot of 15 cmφ, 1/2 volume of 1 cm alumina sintered balls and titanium oxide (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) fine powder 414 gr and copolyamide resin (Alamine CM-).
8000, manufactured by Toray Industries, Inc., 54 gr, methanol 275 gr and butanol 117 gr were put therein, milled for 24 hours, and then diluted with methanol 53.2 gr and butanol 22.8 gr to obtain a 50 wt% intermediate layer coating solution. .. Five pots of this were prepared. The specific gravity of the resin used for the intermediate layer is 1.1, and the specific gravity of titanium oxide is 4,
2, the titanium oxide / resin of the intermediate layer has a volume ratio of 2
It becomes / 1. The intermediate layer coating solution was applied onto the undercoat layer by dip coating and dried by heating at 110 ° C. for 30 minutes to form an intermediate layer having a thickness of 2 μm.

Next, a glass pot of 15 cmφ is filled with 1 volume.
/ 2 amount of 1 cm φ PSZ balls and 300 g of 2.7 wt% cyclohexanone solution of polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) and the azo pigment No. 39 and then milled for 72 hours. Further, 500 g of methyl ethyl ketone was additionally charged and milling was carried out for another 24 hours to obtain a charge generation layer coating solution. Five pots of this were prepared. This coating solution is applied onto the above intermediate layer by dip coating, and 120
It was heated and dried at 0 ° C. for 20 minutes to form a charge generation layer having a film thickness of 0.3 μm.

Next, (charge transfer layer coating liquid) 450 parts of the compound of the following structural formula 3

[Chemical 3] Polycarbonate (Brand name Panlite C1400: Teijin Chemical Co., Ltd.) 500 parts Silicone oil (Brand name KF50: Shin-Etsu Silicone Co., Ltd.) 0.1 part Tetrahydrofuran 4000 parts Dip coating of charge transport layer coating liquid And 130 ℃, 2
A charge transport layer having a film thickness of 20 μm was formed by drying for 0 minutes to prepare an electrophotographic photosensitive member of Example 2.

Example 3 Copolyamide resin (trade name: Alamin CM-800)
No. 0, manufactured by Toray Industries, Inc., 150 parts was dissolved in 3395 parts of methanol and 1455 parts of butanol to obtain an undercoat layer coating solution. This undercoat layer coating solution was vacuum-deposited with Al and had a diameter of 1
Dip-coat on a biaxially stretched polyester cylinder of 46 mm, length 340 mm and thickness about 75 μm, 110 ° C., 1
It was heated and dried for 0 minutes to form an undercoat layer having a thickness of 0.1 μm.

Next, in a hard glass pot of 15 cmφ, 1/2 volume of 1 cm alumina sintered balls and calcium oxide (Furuuchi Chemical Co., Ltd .: purity 99.99%) fine powder 3
35 gr and 50 wt% oil-free alkyd resin (Beckolite M6401-50, Dainippon Ink and Chemicals, Inc.)
(Produced by Mitsui Chemical Co., Ltd.) and 83 g of butylated melamine resin (Super Beckamine G821-60, manufactured by Dainippon Ink and Chemicals, Inc.) having a solid content concentration of 60% by weight and 48 g of methyl ethyl ketone and 280 gr are milled for 24 hours and then 65 gr of methyl ethyl ketone. Was diluted with to obtain a 50% by weight intermediate layer coating solution. Five pots of this were prepared.

The specific gravity of the resin used for the intermediate layer is 1.
4, and since the specific gravity of calcium oxide is 3.4, the calcium oxide / resin in the intermediate layer has a volume ratio of 2/1. The intermediate layer coating solution is dip-coated on the undercoat layer,
It was dried and cured at 20 ° C. for 20 minutes to form an intermediate layer having a thickness of 2 μm. The charge generation layer and the charge transport layer were formed in the same manner as in Example 1 to prepare the electrophotographic photosensitive member of Example 3.

Example 4 18% of 50% by weight of oil-free alkyd resin (Beckolite M6401-50, manufactured by Dainippon Ink and Chemicals, Inc.)
Butyl melamine resin (Super Beckamine G821-60, manufactured by Dainippon Ink and Chemicals, Inc.) having 0 gr and a solid content concentration of 60% by weight was used as 100 gr of methyl ethyl ketone 472.
It was dissolved in 0 gr to give an undercoat layer coating solution. This undercoat layer coating solution was electroplated to a diameter of 146 m.
m, a length of 340 mm, and a thickness of about 30 μm were applied onto a nickel cylinder by dip coating, and dried and heated at 130 ° C. for 15 minutes to form an undercoat layer having a thickness of 0.1 μm. Then 15 cmφ
½ volume of 1 cm alumina sintered ball and calcium fluoride (Furuuchi Chemical Co., Ltd .: 9)
(99%) fine powder 315gr and solid content concentration 50% by weight
Oil-free alkyd resin (Beckolite M6401
-50, Dainippon Ink and Chemicals Co., Ltd. 83 gr, 48 g of butylated melamine resin (Super Beckamine G821-60, Dainippon Ink and Chemicals Co., Ltd.) having a solid content of 60% by weight, and methyl ethyl ketone 262 gr. Milling for 24 hours and then methyl ethyl ketone 63
It was diluted with gr to obtain a 50 wt% intermediate layer coating solution. Five pots of this were prepared.

The specific gravity of the resin used for the intermediate layer is 1.
4 and the specific gravity of calcium fluoride is 3.2, the volume ratio of calcium fluoride / resin in the intermediate layer is 2/1. The intermediate layer coating solution is dip-coated on the undercoat layer,
It was dried and cured at 20 ° C. for 20 minutes to form an intermediate layer having a thickness of 2 μm. The electrophotographic photoreceptor of Example 4 was prepared in the same manner as in Example 1 except that the charge generation layer and the charge transport layer were formed.

Example 5 Copolymerized polyamide resin (trade name: Alamine CM-800
No. 0, manufactured by Toray Industries, Inc., 150 parts was dissolved in 3395 parts of methanol and 1455 parts of butanol to obtain an undercoat layer coating solution. This undercoat layer coating solution is dip-coated on a nickel cylinder having a diameter of 146 mm, a length of 340 mm and a thickness of about 30 μm, which is prepared by electroplating, and dried by heating at 110 ° C. for 10 minutes to give a thickness of 0.1 μm. An undercoat layer was formed.

Next, in a hard glass pot of 15 cmφ, ½ of the volume of 1 cm alumina sintered balls and silicon oxide (manufactured by Kojundo Chemical Co., Ltd .: purity 99.9%) fine powder 221.
gr and oil-free alkyd resin having a solid content of 50% by weight (Beckolite M6401-50, manufactured by Dainippon Ink and Chemicals, Inc.) 83 gr and butylated melamine resin having a solid content of 60% by weight (Super Beckamine G821-60, 48 gr of Dainippon Ink and Chemicals, Inc. and 183 gr of methyl ethyl ketone were added and milled for 24 hours, and then diluted with 48 gr of methyl ethyl ketone to obtain a 50 wt% intermediate layer coating solution. Five pots of this were prepared.

The specific gravity of the resin used for the intermediate layer is 1.
4, and since the specific gravity of silicon oxide is 2.2, the volume ratio of silicon oxide / resin in the intermediate layer is 2/1. The intermediate layer coating solution is applied by dip coating on the undercoat layer at 130 ° C. for 2
It was dried and cured for 0 minutes to form an intermediate layer having a thickness of 2 μm. The electrophotographic photoreceptor of Example 5 was prepared in the same manner as in Example 1 except that the charge generation layer and the charge transport layer were formed.

Comparative Example 1 An electrophotographic photosensitive member of Comparative Example 1 was prepared in the same manner as in Example 1 except that the intermediate layer was not provided.

Comparative Example 2 Comparative Example 2 is the same as Example 1 except that the intermediate layer is not provided and the thickness of the undercoat layer is 1.5 μm.
An electrophotographic photoconductor of was prepared.

Comparative Example 3 An electrophotographic photosensitive member of Comparative Example 3 was prepared in the same manner as in Example 1 except that the undercoat layer was not provided.

Each electrophotographic photosensitive member prepared as described above was subjected to an electrostatic copying paper test apparatus (Kawaguchi Denki Seisakusho SP-428).
Was used to perform corona discharge at −6 KV for 20 seconds for charging, and the surface potential (V ₂ ) 2 seconds after the start of charging was measured. Further, after the charging is finished, the potential is held in a dark place for 20 seconds to reduce the potential holding ratio (Vk) (= potential after 20 seconds of dark decay / charge 20).
The potential after 2 seconds) was determined. After the dark decay for 20 seconds is completed, the tungsten lamp with a color temperature of 2856 ° k is heated to 150 ° C.
surface potential Vr (residual potential) after irradiation with lux · sec
Was measured. Then, the surface potential of −800 V was charged again, and then the exposure amount S required for the surface potential to be attenuated to −400 V was measured by exposing the tungsten lamp at 5 lux. This measurement was performed in an environment of 22 ° C./50% and 10 ° C./15%.

Further, in order to know the repeated fatigue characteristics under low temperature and low humidity (10 ° C./15%), the photoconductor was irradiated with 45 lux of light by a tungsten lamp, and the current flowing through the photoconductor was set to −9.6 μA. Charging and exposure were alternately repeated for 10 minutes while adjusting the applied voltage so that the characteristics after fatigue were measured in the same manner as above. Further, in order to evaluate the adhesiveness between the photosensitive layer and the substrate, the appearance of the photoreceptor after 500,000 rotations was observed with a belt transport tester in which each electrophotographic photoreceptor was modified from FT2070 (manufactured by Ricoh Co., Ltd.). .. The results are shown in Table 2.

[Table 2]

Examples 6 to 7 Electrophotographic photosensitive members of Examples 6 to 7 were prepared in the same manner as in Example 1 except that the thickness of the undercoat layer was changed to 0.25 μm and 0.05 μm. Created.

Examples 8 to 9 Electrophotographic photosensitive members of Examples 8 to 9 were prepared in the same manner as in Example 3 except that the thickness of the undercoat layer was changed to 0.25 μm and 0.05 μm. Created.

Examples 10 to 11 Electrophotographic photoreceptors of Examples 10 to 11 were prepared in the same manner as in Example 4 except that the thickness of the undercoat layer was changed to 0.25 μm and 0.05 μm. Created.

Examples 12 to 13 Electrophotographic photoreceptors of Examples 12 to 13 were prepared in the same manner as in Example 1 except that the thickness of the undercoat layer was changed to 0.5 μm and 0.02 μm. Created.

Examples 14 to 15 Electrophotographic photoreceptors of Examples 14 to 15 were prepared in the same manner as in Example 3 except that the thickness of the undercoat layer was changed to 0.5 μm and 0.02 μm. Created.

Examples 16 to 17 Electrophotographic photosensitive members of Examples 16 to 17 were prepared in the same manner as in Example 4 except that the thickness of the undercoat layer was changed to 0.5 μm and 0.02 μm. Created. Next, each electrophotographic photoreceptor prepared as described above was evaluated in the same manner as in Example 1. The results are shown in Table 3.

[Table 3]

Examples 18 to 19 Example 18 was carried out in the same manner as in Example 1 except that the titanium oxide / resin capacity ratio of the intermediate layer was changed to 1.3 / 1 and 2.7 / 1. .About.19 electrophotographic photoconductors were prepared.

Examples 20 to 21 Example 3 was repeated except that the volume ratio of calcium oxide / resin in the intermediate layer was changed to 1.3 / 1 and 2.7 / 1.
The electrophotographic photoreceptors of Examples 20 to 21 were prepared in the same manner as in.

Examples 22 to 23 Example 4 was repeated except that the intermediate layer calcium fluoride / resin capacity ratio was changed to 1.3 / 1 and 2.7 / 1.
Electrophotographic photoreceptors of Examples 22 to 23 were prepared in the same manner as in.

Comparative Examples 4 to 5 Comparative Example 4 was carried out in the same manner as in Example 1 except that the capacity ratio of titanium oxide / resin in the intermediate layer was changed to 0.9 / 1 and 3.6 / 1. .About.5 electrophotographic photoconductors were prepared.

Comparative Examples 6 to 7 Example 3 is different from Example 3 except that the volume ratio of calcium oxide / resin in the intermediate layer is changed to 0.9 / 1 and 3.6 / 1.
The electrophotographic photosensitive members of Comparative Examples 6 to 7 were prepared in the same manner as in.

Comparative Examples 8 to 9 Example 4 was repeated except that the calcium fluoride / resin capacity ratio of the intermediate layer was changed to 0.9 / 1 and 3.6 / 1.
Electrophotographic photoreceptors of Comparative Examples 8 to 9 were prepared in the same manner as in. Next, each electrophotographic photoreceptor prepared as described above was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[Table 4] Comparative Examples 11, 13, and 15 were not characterized because air bubbles contained in the charge transport layer caused a large number of bubbles due to air contained in the intermediate layer during coating and drying of the charge transport layer.

[0081]

The electrophotographic photoreceptor of the present invention has the above-mentioned constitution, and since the undercoating layer made of a resin and the intermediate layer of the specific composition are provided between the conductive substrate and the photoconductive layer, the substrate and the intermediate layer are provided. The adhesiveness of the layer is improved, so that the printing durability by repeated use is improved, and further, the increase in residual potential is small even after repeated charging and exposure, which is a remarkable effect. Further, according to the electrophotographic photoreceptor of the present invention, it is possible to prevent the occurrence of an abnormal image due to optical interference even in exposure using a coherent light such as a laser printer.

Claims (3)

[Claims] 1. An electrophotographic photosensitive member having a photoconductive layer provided on a conductive substrate, wherein a white pigment and a binder resin are main components between the conductive substrate and the photoconductive layer, and the white pigment is bound to the photoconductive layer. An intermediate layer having a volume ratio of the binder resin in the range of 1/1 to 3/1 was provided, and an undercoat layer made of a binder resin was provided between the conductive substrate and the intermediate layer. An electrophotographic photosensitive member. 2. The electrophotographic photosensitive member according to claim 1, wherein the white pigment is titanium oxide, calcium oxide or calcium fluoride. 3. The undercoat layer has a film thickness of 0.03 μm or more.
The electrophotographic photosensitive member according to claim 1, which has a thickness of 3 μm or less.