JP3150003B2 - Manufacturing method of electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to an electrophotographic photosensitive member used for a copying machine, a printer, and the like, and more particularly, to an electrophotographic photosensitive member which does not increase in residual potential and has excellent charge stability even when used repeatedly for a long period of time. .

[0002]

2. Description of the Related Art Inorganic substances such as selenium, cadmium sulfide, and zinc oxide are known as photoconductive materials for electrophotographic photosensitive members. However, these inorganic substances are not necessarily satisfactory in characteristics such as photosensitivity, heat stability, durability and the like, and manufacturing conditions required for the electrophotographic photosensitive member. For example, selenium is easily crystallized due to heat, dirt, and the like, and its characteristics are easily deteriorated. In addition, there are drawbacks such as manufacturing costs, impact resistance, toxicity, and the like, requiring care in handling. A photoreceptor using cadmium sulfide has poor moisture resistance and durability, and has problems such as toxicity. Zinc oxide also has the drawback of poor moisture resistance and durability.

On the other hand, in contrast to electrophotographic photoreceptors using these inorganic photoconductive materials, photoreceptors using an organic photoconductive material are lighter in weight, easier to form a film, more expensive to manufacture, or have a wider variety of organic compounds. Since then, research has been actively conducted. For example, in the early days,
No. 0496, polyvinyl carbazole and 2,
A photoreceptor containing 4,7-trinitro-9-fluorenone, a photoreceptor sensitized with polyvinyl carbazole described in JP-B-48-25658 with a pyrylium salt dye, or a photoreceptor containing a eutectic complex as a main component Was proposed. However, these photoconductors are not sufficient in sensitivity and durability.

In recent years, a function-separated type photoconductor in which a charge generation layer and a charge transport layer are separated has been proposed.
JP-A-53-133445 discloses a photoreceptor comprising a combination of chlordiane blue and a hydrazone compound described in JP-A-5-42380.
JP-A-4-21728, JP-A-54-22834, and JP-A-58-198043 as a charge transport material.
And JP-A-58-199352 are known. However, these functionally separated photoconductors are not particularly satisfactory in terms of durability, and in recent years, while demands for durability have been further increased, securing charging stability has become a problem that cannot be ignored. . That is, when the charging property is reduced, the image density of a copy is reduced in a copying machine, and in a laser printer using a reversal development method, image quality is reduced such as generation of background stain. In order to solve these problems, it has been proposed to provide an intermediate layer between the conductive substrate and the photosensitive layer. However, when a high resistance material having a high barrier property is used as the intermediate layer to stabilize the chargeability, the chargeability is improved, but the photosensitivity is reduced and the residual potential is increased. In addition, when a material having a relatively low resistance that does not increase the residual potential is used, the chargeability becomes insufficient.

On the other hand, when the photoconductor is actually used in a copying machine, the photoconductor is exposed to ozone generated from a corona charger. Then, the ozone oxidizes the charge transporting material and the like in the photosensitive layer, causing a decrease in sensitivity, an increase in residual potential, or a decrease in charge potential. In order to solve these problems, a stabilizer such as an antioxidant is added to a photoreceptor as disclosed in JP-A-57-122444 and JP-A-61-156052. 1988
Proposals have been made to provide a gas barrier resin layer on a charge transport layer as seen in JP-A-135595.
However, the above-described countermeasures also increase the residual potential. There are drawbacks such as detrimental effects such as reduced sensitivity and insufficient improvement in durability, and a satisfactory photoconductor has not yet been obtained.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art. Specifically, the present invention is excellent in ozone resistance, excellent in charging stability even when used repeatedly, and has a low residual potential. It is an object of the present invention to provide an electrophotographic photoreceptor which does not increase, that is, provides a good image without lowering of image density or background contamination.

[0007]

Means for Solving the Problems As a result of investigations to solve the above problems, the present inventors have found that at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, In an electrophotographic photoreceptor containing an agent, if the expansion rate of the thickness of the charge generation layer before and after coating the charge transport layer of the photoreceptor is 250% or less, the charge stability is excellent even after repeated use, and the residual potential increases No, therefore, it has a long life and high reliability without image density reduction and background contamination,
We have found that the above-mentioned problems lead to a solution.

According to the present invention, the following inventions are provided.
You. (1) In a method for producing a function-separated electrophotographic photoreceptor comprising a charge generating layer and a charge transporting layer sequentially laminated on a conductive support and containing a stabilizer, the charge transporting layer of the photoreceptor is the provided by a spray coating method, and process for producing an electrophotographic photoreceptor, wherein the coating expansion ratio before and after the charge generation layer thickness is in the range of below formula (I). DG0: Thickness of charge generation layer before coating of charge transport layer (μm) DG1: Thickness of charge generation layer after coating of charge transport layer (μm) (2) Degree of butyralization of binder resin of charge generation layer is 6
The method for producing an electrophotographic photoreceptor as described in 1 above, wherein the polyvinyl butyral is at least 8 mol%. (3) The method for producing an electrophotographic photosensitive member according to the above , wherein the ratio of the charge generating substance (P) to the binder resin (R) in the charge generating layer is P / R = 2/1 or less by weight.

According to the electrophotographic photoreceptor of the present invention, in a function-separated type electrophotographic photoreceptor containing a stabilizer in the photosensitive layer, the coefficient of expansion of the charge generating layer by coating the charge transport layer is 250.
%, The increase in the residual potential and the fluctuation in sensitivity, which are side effects of the stabilizer, are suppressed, and the durability becomes excellent. The coefficient of expansion of the charge generation layer is the ratio of the type of solvent used when coating the charge transport layer and the ratio thereof when they are used as a mixed solvent,
The solid content of the liquid can be controlled, and for example, the expansion rate can be reduced by using a low boiling point solvent or by increasing the ratio, or by increasing the solid content.

In addition, the present inventors further studied on this point and found that polyvinyl butyral having a butyralization degree of 68 mol% or more was used as the binder resin in the charge generation layer, and the charge generation material (P) was used. It has been found that by setting the ratio of the binder resin (R) to P / R = 2/1 or less by weight, it is possible to further suppress the increase in the residual potential and the sensitivity deterioration.

Although the reason for this has not been sufficiently clarified at present, the charge trapping site in the function-separated type electrophotographic photoreceptor containing a stabilizer has a charge generating layer or a charge generating layer and a charge transporting layer. It is considered that these are caused by controlling or optimizing these sites due to the layer interface.

The butyral resin according to the present invention is synthesized by reacting polyvinyl alcohol with butyraldehyde. However, the following general formula (II) (Formula 1) )).

Embedded image (L, m, and n each represent the degree of polymerization of polyvinyl butyral, vinyl acetate, and polyvinyl alcohol components.)

In general, a butyral resin changes its physical and chemical properties depending on its composition, and also changes its thermal properties, mechanical properties and solution viscosity depending on its degree of polymerization. The butyral resin that can be used in the present invention is a polyvinyl butyral component in the general formula (II) (polymerization degree l).
) Are contained in an amount of 68 mol% or more. Preferably, the polyvinyl alcohol component in formula (II) (sliding component indicating the degree of polymerization n) contains less than 30 mol%. The degree of butyralization is JIS
It can be determined from K6728-5.5, IR absorption spectral absorbance ratio and the like.

Examples of the conductive support used in the electrophotographic photoreceptor of the present invention include aluminum, brass, stainless steel, nickel and other metal drums and sheets, polyethylene terephthalate, polypropylene, nylon, paper, and other materials made of aluminum and nickel. Such as metal deposited,
Laminated or coated with a conductive paint, plastic drums and sheets in which a conductive pigment such as carbon is dispersed, and the like can be mentioned.

If necessary, an intermediate layer containing a resin or a resin and a pigment may be provided between the conductive support and the photosensitive layer. The pigment dispersed in the intermediate layer may be a commonly used powder, but a white color having almost no absorption in near-infrared light or a color close to this is desirable in view of increasing sensitivity. Such pigments include, for example, titanium oxide, zinc oxide,
Examples thereof include metal oxides represented by tin oxide, indium oxide, zirconium oxide, alumina, and silica, and those having no hygroscopicity and little environmental change are desirable. In particular, in the case of a photoreceptor used for a laser printer or the like that writes an image with coherent light such as laser light, it is better to use a white pigment having a large bending ratio in order to prevent the occurrence of moire.

As the binder resin for the intermediate layer used in the present invention, an appropriate one can be used. Considering that a photosensitive layer is coated thereon with a solvent,
Resins having high solvent resistance to general organic solvents are desirable. Such a resin forms a three-dimensional network structure such as a water-soluble resin such as polyvinyl alcohol, casein and sodium polyacrylate, an alcohol-soluble resin such as copolymerized nylon and methoxymethylated nylon, a polyurethane, a melamine resin, and an epoxy resin. Curable resin. The thickness of the intermediate layer is preferably about 0.1 to 50 μm, particularly preferably 0.3 to 20 μm. Further, the ratio of the pigment (F) and the binder resin (R) in the intermediate layer is preferably in the range of 1/1 to 3/1 by volume ratio.
When R is less than 1/1, the intermediate layer tends to be affected by the properties of the binder resin, and when R exceeds 3/1, the space in the intermediate layer is increased, and air bubbles are liable to be generated when the upper photosensitive layer is formed.

The function-separated type photoreceptor has a charge generation layer containing a charge generation substance and a binder resin on a support, and a charge transport layer containing a charge transport substance and a binder resin formed thereon. In the case of forming, there are preferable ranges for the film thickness and the ratio of the substance. In the charge generation layer,
The ratio of the charge-generating substance (P) to the binder resin (R) is P / R = 1/0 to 1/4 by weight, and especially considering the stability of sensitivity at the time of repeated use, P / R = 2/1 to 1. The thickness is preferably 1/2, and the thickness is preferably 0.1 to 5 μm. In the charge transport layer, the ratio of the charge transport material (D) to the binder resin (R) is a weight ratio, D / R = 1/5 to 2/1, and the film thickness is 5%.
It is preferable to set it to 50 μm. Stabilizers include antioxidants such as quinones, phenols, hindered phenols, hindered amines, phosphorus, sulfur, benzofurans, chromans and derivatives thereof, benzophenones, benzotriazoles, salicylates and the like. Examples include commercially available products such as ultraviolet absorbers such as derivatives, and products synthesized by various conventionally known methods, depending on the charge generating substance used, the charge transporting substance, and the desired charge stability. To select as appropriate. In the case of a function-separated type, the addition to the charge generation layer and the charge transport layer is effective because the solvent diffuses to other layers due to the solvent at the time of application. When added to the layer, the charge transport material may be added in an amount of 0.01 to 1
When added to the charge generation layer in an amount of 0.0% by weight, it is preferable to add 0.1 to 20.0% by weight based on the charge generation substance.

As the charge generating material that can be used in the electrophotographic photoreceptor of the present invention, any of inorganic substances and organic substances can be used as long as they absorb light to generate charge carriers.

Examples of the inorganic substance include amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, zinc oxide, amorphous silicon and the like.

As the organic substance, for example, CI Pigment Blue 25 [Color Index (CI) 211]
80], C.I. Pigment Red 41 (CI 212
00), CI Acid Red 52 (CI 4510
0), CI Basic Red 3 (CI4521)
0), further, a phthalocyanine-based pigment having a porphyrin skeleton, an azulenium salt pigment, a squaric salt pigment,
Azo pigments having a carbazole skeleton (JP-A-53-95)
033), an azo pigment having a stilstilbene skeleton (described in JP-A-53-138229), and an azo pigment having a triphenylamine skeleton (described in JP-A-53-1).
32547), an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728),
Azo pigments having an oxadiazole skeleton (JP-A-54-1979)
No. 12742), an azo pigment having a fluorenone skeleton (described in JP-A-54-22834), and an azo pigment having a bisstilbene skeleton (described in JP-A-54-1773)
No. 3), an azo pigment having a distyryloxadiazole skeleton (described in JP-A-54-2129), and an azo pigment having a distyrylcarbazole skeleton (described in JP-A-5-2129).
4-17734), a trisazo pigment having a carbazole skeleton (JP-A-57-195767,
Phthalocyanine pigments such as C.I. Pigment Blue 16 (CI 74100), C.I.
73410), a sea butt die (CI7303)
0) and the like; perylene pigments such as Argoscarlet B (manufactured by Violet) and Indus Scarlet R (manufactured by Bayer); anthraquinone or polycyclic quinone pigments; quinone imine pigments; diphenylmethane and triphenylmethane Pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments,
Bisbenzimidazole pigments and the like can be mentioned. These charge generating substances are used alone or in combination of two or more.

The binder resin used for the charge generation layer includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and vinyl chloride. Vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyalate resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin And a thermoplastic or thermosetting resin such as melamine resin, urethane resin, phenol resin and alkyd resin. Above all, as a binder resin for the charge generation layer, polyvinyl butyral is superior to other resins in terms of dispersion stability of a coating solution and charge stability and sensitivity deterioration upon repeated use, and particularly contains a stabilizer. Among electrophotographic photoreceptors, those having a butyral degree of 68 mol% or more are excellent.

The charge transport material includes a hole transport material and an electron transport material. Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylfebatrene, oxazole derivatives, and oxazole. Diazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (P-diethylaminostyryl) anthracene, 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazolin, phenylhydrazones, α Electron-donating substances such as -phenylstilbene derivatives. Examples of the electron transporting substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinonedimethane, 2,4,7-trinitro-9-fluorenone,
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-trinitrodibenzothiophene-5,
An electron accepting substance such as 5-dioxide is exemplified.

These charge transport materials are used alone or in combination of two or more. Further, as the binder resin used for the charge transport layer, 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, polycarbonate, Thermoplastic or thermosetting of cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, etc. Resin.

In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer. As a plasticizer,
Those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are.
A suitable amount is about weight%. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil are used, and the amount of the silicone oil is suitably about 0 to 1% by weight based on the binder resin. In the present invention, it is possible to further provide an insulating layer and a protective layer on the photoreceptor. As a method for forming the auxiliary layer such as the photosensitive layer and the intermediate layer and the protective layer as described above, a dip coating method, a spray coat method, a bead coat method, or the like can be used. In particular, as a method for coating the charge transport layer, a spray coating method having a large margin in film forming properties and other points with respect to changes in the type of coating solvent, mixed solvent ratio, solid content, and the like is preferable.

[0025]

Next, the present invention will be described in more detail with reference to examples.

Example 1 10 parts by weight of an alkyd resin [Beccosol TD-50-30 (manufactured by Dainippon Ink and Chemicals)] and a melamine resin [Beckamine P-138 (manufactured by Dainippon Ink and Chemicals)] 7
Was dissolved in 30 parts by weight of methyl ethyl ketone, 60 parts by weight of titanium oxide fine powder [TP-2 (manufactured by Fuji Titanium Industry Co., Ltd.)] was added thereto, dispersed by a ball mill for 24 hours, and 30 parts by weight of methyl ethyl ketone was further added. After dilution, a solution for an intermediate layer was prepared. This was dip-coated on a 0.2 mm-thick aluminum plate [A1080 (manufactured by Sumitomo Light Metal Co., Ltd.)] and dried at 150 ° C. for 20 minutes to form an intermediate layer having a thickness of 2 μm. Next, 1 part by weight of a polyester resin [Vylon 200 (manufactured by Toyobo)] was dissolved in 50 parts by weight of cyclohexanone, and trisazo pigment of the following structural formula (III) was added thereto.

Embedded image 2.5 parts by weight were added and dispersed in a ball mill for 72 hours. Further, 50 parts by weight of cyclohexanone was added and dispersed for 12 hours, and this was diluted with cyclohexanone while stirring to obtain a solid content of 1.0% by weight. The thus obtained coating solution for a charge generation layer is spray-coated on the intermediate layer,
After drying at 20 ° C. for 10 minutes, a charge generation layer was formed. At this time, the thickness of the charge generation layer formed under the same coating conditions was measured by a transmission electron microscope and found to be 0.20 μm. Next, an α-phenylstilbene compound represented by the following structural formula (IV) is used as a charge transporting substance.

Embedded image 8 parts by weight, polycarbonate resin [Panlite L-12
50 (manufactured by Teijin Chemicals Limited)], 10 parts by weight, silicone oil [KF-50 (manufactured by Shin-Etsu Chemical Co., Ltd.)] 0.001 part by weight, and 2,5-di-t-Bu-hydroquinone [Tokyo Chemical Was dissolved in a mixed solvent of 108 parts by weight of tetrahydrofuran and 72 parts by weight of cyclohexanone. The coating liquid for a charge transport layer thus obtained was spray-coated on the charge generation layer,
Dried for 0 minutes to form a 25 μm thick charge transport layer,
An electrophotographic photosensitive member of Example 1 was prepared. The thickness of the charge generation layer after the formation of the photosensitive layer of the electrophotographic photoreceptor of Example 1 thus prepared was 0.50 μm when measured in the same manner as before the charge transport layer was coated. The expansion rate was 250% compared to before.

Example 2 The electrophotographic photosensitive member of Example 2 was prepared in the same manner as in Example 1 except that the solvent of the coating solution for the charge transport layer was changed to 120 parts by weight of tetrahydrofuran and 60 parts by weight of cyclohexanone. Created. The film thickness of the charge generation layer of the electrophotographic photosensitive member of Example 2 thus formed after the formation of the photosensitive layer was 0.40 μm, and the expansion rate was 200% as compared with before the charge transport layer was coated. Was.

Comparative Example 1 The electrophotographic photosensitive member of Comparative Example 1 was prepared in the same manner as in Example 1, except that the solvent for the coating solution for the charge transport layer was changed to 86 parts by weight of tetrahydrofuran and 94 parts by weight of cyclohexanone. Created. The thickness of the charge generation layer after the formation of the photosensitive layer of the electrophotographic photosensitive member of Comparative Example 1 thus formed was 0.60 μm, and the expansion rate was 300% as compared with that before the application of the charge transport layer. Was.

Comparative Example 2 The electrophotographic photosensitive member of Comparative Example 2 was prepared in the same manner as in Example 1 except that the solvent of the coating solution for the charge transport layer was changed to 64 parts by weight of tetrahydrofuran and 116 parts by weight of cyclohexanone. Created. The thickness of the charge generation layer of the electrophotographic photosensitive member of Comparative Example 2 thus formed after the formation of the photosensitive layer was 0.75 μm, and the expansion rate was 375% as compared with that before the application of the charge transport layer. Was.

Example 3 The electrophotographic photosensitive member of Example 3 was prepared in the same manner as in Example 1 except that the solvent for the coating solution for the charge transport layer was changed to 81 parts by weight of tetrahydrofuran and 54 parts by weight of cyclohexanone. Created. The film thickness of the charge generation layer of the electrophotographic photosensitive member of Example 3 thus formed after the formation of the photosensitive layer was 0.37 μm, and the expansion rate was 185% as compared with that before the application of the charge transport layer. Was.

Comparative Examples 3 to 6 The stabilizers 2,5 were obtained from Examples 1 and 2 and Comparative Examples 1 and 2.
An electrophotographic photoreceptor excluding -di-t-butylhydroquinone was prepared. The change in the charge generation layer was almost the same as in Comparative Examples 1 and 2.

Comparative Example 7 The electrophotographic photosensitive member of Comparative Example 3 was prepared in the same manner as in Example 1 except that the solvent of the coating solution for the charge transport layer was changed to 144 parts by weight of tetrahydrofuran and 96 parts by weight of cyclohexanone. Created. The thickness of the charge generation layer of the electrophotographic photosensitive member of Comparative Example 3 thus formed after the formation of the photosensitive layer was 0.60 μm, and the expansion rate was 300% as compared with that before the application of the charge transport layer. Was.

Example 4 8 parts by weight of the charge-transporting substance of the structural formula (IV) (formula 3), 10 parts by weight of a Z-type polycarbonate resin having a molecular weight of about 60,000, silicone oil [KF-50 (manufactured by Shin-Etsu Chemical Co., Ltd.)] 0.0
01 parts by weight and 0.08 parts by weight of 2,5-di-t-Bu-hydroquinone (manufactured by Tokyo Chemical Industry) as a stabilizer were dissolved in 60 parts by weight of tetrahydrofuran and 30 parts by weight of a mixed solvent of methylene chloride. The thus obtained coating solution for a charge transport layer was applied onto the charge generation layer of Example 1 by dip coating, and dried at 110 ° C. for 10 minutes to form a charge transport layer having a thickness of 18 μm. Created body. The film thickness of the charge generating layer of the electrophotographic photosensitive member of Example 4 thus formed after the formation of the photosensitive layer was 0.45 μm, and the expansion rate was 225% as compared with before the charge transport layer was coated. Was.

Comparative Example 8 An electrophotographic photosensitive member of Comparative Example 8 was prepared in the same manner as in Example 4, except that the solvent of the coating solution for the charge transport layer was changed to 90 parts by weight of tetrahydrofuran. The thickness of the charge generation layer after the formation of the photosensitive layer of the electrophotographic photosensitive member of Comparative Example 8 thus formed was 0.55 μm, and the expansion rate was 275% as compared with that before the application of the charge transport layer. Was.

Examples 5 and 6 and Comparative Examples 9 and 10 In Examples 1 and 2 and Comparative Examples 1 and 2, polyester resin, Vylon 2 which is a binder resin of the charge generation layer was used.
Example 5 was carried out in the same manner as in Examples 1 and 2 and Comparative Examples 1 and 2, except that 00 was changed to a vinyl chloride / vinyl acetate / maleic anhydride copolymer [MF-10 (manufactured by Sekisui Chemical Co., Ltd.)]. , 6 and Comparative Examples 9 and 10 were prepared. The film thicknesses of the charge generation layers of the electrophotographic photoreceptors of Examples 5 and 6 and Comparative Examples 9 and 10 thus formed after the formation of the photosensitive layers were 0.50 μm (250%) and 0.5 μm, respectively.
45 μm (225%), 0.55 μm (275%),
It was 0.70 μm (350%).

Examples 7 and 8 and Comparative Examples 11 and 12 In Examples 1 and 2 and Comparative Examples 1 and 2, polyester resin as a binder resin for the charge generation layer, Vylon 2 was used.
Examples 7, 8, and Comparative Examples were performed in the same manner as in Examples 1 and 2 and Comparative Examples 1 and 2, except that 00 was changed to polyvinyl butyral [XYHL (manufactured by Union Carbide)] having a butyralization degree of 56 mol%. 11 and 12 electrophotographic photosensitive members were prepared. The film thicknesses of the charge generation layers of the electrophotographic photoreceptors of Examples 7 and 8 and Comparative Examples 11 and 12 thus formed after the formation of the photosensitive layers were 0.45 μm (225 μm, respectively).
%), 0.40 μm (200%), 0.55 μm (27
5%) and 0.65 μm (325%).

Examples 9 and 10 and Comparative Examples 13 and 14 In Examples 1 and 2 and Comparative Examples 1 and 2, polyester resin as a binder resin for the charge generation layer, Vylon 2 was used.
Examples 9 and 10 were carried out in the same manner as in Examples 1 and 2 and Comparative Examples 1 and 2, except that 00 was changed to polyvinyl butyral having a degree of butyralization of 65 mol% (S-lec BM-1 (manufactured by Sekisui Chemical Co., Ltd.)). In addition, electrophotographic photosensitive members of Comparative Examples 13 and 14 were prepared. Example 9 created in this way,
The thickness of the charge generation layer after the formation of the photosensitive layer of each of the electrophotographic photoreceptors of Comparative Examples 13 and 14 was 0.50 μm.
(250%), 0.45 μm (225%), 0.60 μm
m (300%) and 0.70 μm (355%).

Examples 11 and 12 and Comparative Examples 15 and 16 In Examples 1 and 2 and Comparative Examples 1 and 2, polyester resin as a binder resin for the charge generation layer,
Examples 11 and 12 were carried out in the same manner as in Examples 1 and 2 and Comparative Examples 1 and 2, except that 00 was changed to polyvinyl butyral having a degree of butyralization of 68 mol% (S-lec BM-2 (manufactured by Sekisui Chemical Co., Ltd.)). In addition, electrophotographic photosensitive members of Comparative Examples 15 and 16 were prepared. Example 1 created in this way
The film thicknesses of the charge generation layers of the electrophotographic photoreceptors of Examples 1 and 12 and Comparative Examples 15 and 16 after the formation of the photosensitive layers were 0.50, respectively.
μm (250%), 0.45 μm (225%), 0.6
0 μm (300%) and 0.75 μm (375%).

Examples 13 and 14 and Comparative Examples 17 and 18 In Examples 1 and 2 and Comparative Examples 1 and 2, polyester resin as a binder resin of the charge generation layer, and Byron 2 were used.
Examples 13 and 14 were carried out in the same manner as in Examples 1 and 2 and Comparative Examples 1 and 2, except that 00 was changed to polyvinyl butyral having a degree of butyralization of 70 mol% (S-lec BM-S (manufactured by Sekisui Chemical Co., Ltd.)). In addition, electrophotographic photosensitive members of Comparative Examples 17 and 18 were prepared. Example 1 created in this way
The thicknesses of the charge generation layers of the electrophotographic photoreceptors of Comparative Examples 3 and 14 and Comparative Examples 17 and 18 after the photosensitive layer formation were 0.50, respectively.
μm (250%), 0.45 μm (225%), 0.6
0 μm (300%) and 0.75 μm (375%).

Examples 15 to 17 In Example 13, the stabilizers were respectively hindered amine-based Sanol LS-770 (manufactured by Sankyo) and hindered phenol and sanol LS-2626 having both hindered amine structures (manufactured by Sankyo). Example 13 except that Vitamin E (manufactured by Tokyo Chemical Industry) having a chroman skeleton was used.
The electrophotographic photoreceptors of Examples 15 to 17 were prepared in the same manner as described above. The film thickness of the charge generation layer after the formation of the photosensitive layer of the electrophotographic photosensitive members of Examples 15 to 17 thus formed was the same as that of Example 13.

Comparative Examples 19 to 21 In Example 13, the stabilizers were respectively hindered amine-based Sanol LS-770 (manufactured by Sankyo), and hanol phenol and sanol LS-2626 having both hindered amine structures (manufactured by Sankyo). Example 13 except that Vitamin E (manufactured by Tokyo Chemical Industry) having a chroman skeleton was used.
The electrophotographic photoreceptors of Comparative Examples 19 to 21 were prepared in the same manner as described above.

Comparative Examples 19 to 21 prepared in this way
The film thickness of the charge generation layer after the formation of the photosensitive layer of the electrophotographic photoreceptor was the same as that of Comparative Example 13. The electrostatic characteristics of the electrophotographic photosensitive member obtained as described above were measured by a dynamic method using EPA-8100 (manufactured by Kawaguchi Electric Works) in a high temperature and high humidity environment of 30 ° C./80% RH. First, the surface potential immediately after charging at an applied voltage of −6 KV for 20 seconds is V
m, the surface potential after dark decay is performed for 20 seconds in the dark as it is, and the dark decay rate Vo / Vm is determined. Further, the surface potential is exposed to monochromatic light of 780 nm (surface illuminance 5 μw / cm ² ). Was measured to determine the exposure amount E1 / 5 (μJ / cm ² ) required to make 1/5 of the surface potential immediately before exposure.
The surface potential after the exposure for 30 seconds was used as the residual potential V30 (−V). Thereafter, irradiation of 5lux of tungsten light with a color temperature of 2856K and repetition of charging at −6 KV were repeated 50,000 times, and the electrostatic characteristics—dark decay rate Vo / Vm ′, sensitivity E1 / 5 ′ (μJ / cm ² ), The residual potential V30 '(-V)-was measured as before. Table 1 shows the results.

Example 18 The procedure of Example 16 was repeated except that the charge generating substance (III) (Chem. 3) was changed to 1.5 parts by weight, and the thickness of the charge generating layer before coating the charge transport layer was 0.3 μm. In the same manner as in Example 16, an electrophotographic photosensitive member of Example 18 was prepared. The film thickness of the charge generation layer after the formation of the photosensitive layer of the electrophotographic photosensitive member of Example 18 thus formed was 0.75 μm (250%). With respect to the electrophotographic photoreceptors of Example 16 and Example 18 thus obtained, the sensitivity E1 / 5 was determined in the same manner as described above under the environment of 23 ° C./55% RH at normal temperature and normal humidity.
Thereafter, the same band ← → exposure of 50,000 times as described above was repeated 10 times, and the change of E1 / 5 was measured. FIG. 1 shows the results.

[Table 1]

[0044]

As described above, the electrophotographic photoreceptor according to the present invention has little stability such as chargeability and residual potential due to repeated fatigue, and has excellent stability.
It has a long life.

[Brief description of the drawings]

FIG. 1 is a graph showing the correlation between the sensitivity of the electrophotographic photosensitive member obtained in Examples 16 and 18 and the number of repetitions.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Satoshi Kurimoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-2-296251 (JP, A) JP-A-Hei 1-315767 (JP, A) JP-A-1-136161 (JP, A) JP-A-1-136159 (JP, A) JP-A-1-136160 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/00-5/16

Claims (3)

(57) [Claims] 1. A least a charge generation layer on a conductive support and formed by laminating a charge transporting layer successively, and, in the method for producing a functional separation type electrophotographic photoreceptor containing a stabilizer, the charge of the photosensitive member A transport layer is provided by a spray coating method, and
One charge transport layer electrophotographic photoreceptor coating before and after the charge generation layer thickness of the expansion rate is characterized by a range of the following formula (I)
Manufacturing method . DG0: Thickness of charge generation layer before coating of charge transport layer (μm) DG1: Thickness of charge generation layer after coating of charge transport layer (μm) 2. A method for producing an electrophotographic photosensitive member according to claim 1 binder resin of the charge generation layer is polyvinyl butyral or butyralization degree 68 mol%. 3. A charge generating substance (P) in a charge generating layer,
The ratio of the binder resin (R) is P / R = 2/1 by weight.
2. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the method is as follows.