JP3054777B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a surface protective layer in which a metal oxide powder is dispersed in a binder resin. About.

[Conventional technology]

Conventionally, as a photoreceptor for electrophotography, one provided with a photoconductive layer mainly composed of selenium or a selenium alloy on a conductive support, zinc oxide, an inorganic photoconductive material such as cadmium oxide dispersed in a binder. And those using organic photoconductive materials such as poly-N-vinylcarbazole and trinitrofluorenone or azo pigment, and those using amorphous silicon.

The demand for reliability for maintaining high image quality for these photoconductors for a long time is increasing year by year. However, when the photoconductive layer is exposed, damage due to corona discharge during the charging process and physical or chemical damage due to contact with other members during the copying process have reduced the life of the photoreceptor.

As a method for solving such a defect, a technique of providing a protective layer on the surface of a photoreceptor is known. Specifically, a method of providing an organic film on the surface of a photosensitive layer (Japanese Patent Publication No. 38-1544)
6), a method of providing an inorganic oxide (Japanese Patent Publication No. 43-14517), a method of providing an adhesive layer and then laminating an insulating layer (Japanese Patent Publication No. 43-2759)
1) or a-S by plasma CVD or photo CVD
A method of laminating an i-layer, an a-Si: N: H layer, an a-Si: O: H layer, and the like (JP-A-57-179859 and JP-A-59-58437) is disclosed.

However, the protective layer has an electrophotographic high resistance (10 ¹⁴ Ω)
(Cm or more), there is a problem of an increase in residual potential and accumulation of charged potential during repetition, which is not practical.

As a technique for compensating for the above-mentioned drawbacks, a method in which a protective layer is used as a photoconductive layer (Japanese Patent Publication Nos. 48-38427, 43-16198, and 49-10
258, USP-2901348), a method of adding a transfer agent typified by a dye or a Lewis acid to the protective layer (Japanese Patent Publication No. 44-834, Japanese Patent Application Laid-Open No. 53-133444), or a method of adding fine particles of metal or metal oxide. Method for controlling resistance of protective layer (JP-A-53-3338)
Etc. have been proposed.

However, in such a case, light is absorbed by the protective layer and the amount of light reaching the photoconductive layer is reduced, resulting in a problem that the sensitivity of the electrophotographic photosensitive member is reduced.

From this point of view, as disclosed in JP-A-57-30846, by dispersing metal oxide fine particles having an average particle diameter of 0.3 μm or less in a surface protective layer as a resistance control agent, the material is substantially exposed to visible light. There is a method to make it transparent. The electrophotographic photoreceptor having this surface protective layer has a small decrease in sensitivity,
The mechanical strength of the surface protective layer also increases, and the durability improves.

However, when this photoreceptor is incorporated in an actual copying machine, there is a drawback that a residual potential is generated and a background stain is generated on an image. It has been found that this residual potential is generated by residual charges accumulated on the surface protective layer, and increases remarkably as the copying speed increases.

[Problems to be solved by the invention]

The present invention has been made in view of such circumstances, and reduces the residual charge of an electrophotographic photosensitive member having a protective layer in which a metal oxide is dispersed in a binder resin, and can be used in a high-speed copying machine. An object of the present invention is to provide a highly reliable electrophotographic photoreceptor capable of obtaining a good-quality image without causing background stain on the image.

[Means for solving the problem]

The inventors of the present invention have been conducting research to solve the above-described problems, and as a result, have obtained an electron-emitting device in which a photoconductive layer and a surface protective layer in which a metal oxide is dispersed in a binder resin are sequentially laminated on a conductive support. In the photographic photoreceptor, it has been found that charges are trapped on the surface of the protective layer to generate a residual potential. As a result of further research, we improved the charge injection from the protective layer surface,
In order to lower the residual potential, it has been found that it is effective to expose the metal oxide on the surface of the protective layer and reduce the contact angle with water to 80 ° or less. The present invention has been made based on these findings.

That is, in the electrophotographic photoreceptor of the present invention, a photoconductive layer and a surface protective layer in which metal oxide particles are dispersed in a binder resin are sequentially laminated on a conductive support. Is exposed to the surface, and the contact angle with water is 80 ° or less.

 Hereinafter, the present invention will be described in more detail.

The configuration of the electrophotographic photoreceptor used in the present invention is as follows. In an electrophotographic photoreceptor in which a photoconductive layer and a surface protective layer are sequentially laminated on a conductive support, the surface protective layer is formed by bonding a metal oxide powder to a binder resin. Consists of layers dispersed therein.

The metal oxide fine powder used in the present invention includes tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, tin-doped indium oxide and the like. Can be used. Two or more of these metal or metal oxide fine powders may be mixed. The average particle size of these fine powders is preferably 0.3 μm or less, more preferably 0.1 μm or less, from the viewpoint of the transmittance of the protective layer.

Examples of the binder resin used in the present invention include a silicone resin, a polyurethane resin, an acrylic resin, a polyester resin, a polycarbonate resin, a polystyrene resin, and an epoxy resin.

The protective layer of the present invention is obtained by dispersing a metal oxide fine powder in a binder resin solution, coating and drying the photoconductive layer on the photoconductive layer, and then exposing the surface of the metal oxide to the surface by means such as polishing. May be set to be equal to or less than 80 °. In this case, the polishing means includes, for example, a liquid honing, a super-finishing method, a buff polishing method, a polishing tape rubbing method and the like.
If the contact angle between the protective layer and water exceeds 80 °, the residual potential rises markedly, resulting in poor durability.

Various additives may be added to the protective layer for the purpose of improving dispersibility, adhesiveness, or smoothness.

As the photoconductive layer used in the present invention, Se, Se-Te, As
An Se alloy such as ₂ Se ₃ , a dispersion of particles of a II-VI compound such as Zn0, CdS, and CdSe in a resin, an organic photoconductive material such as polyvinyl carbazole, or a-Si is used.

The configuration of the photoconductive layer is not particularly limited, and may be a single layer or a laminate of the charge generation layer and the charge transport layer.

Further, an electrical barrier layer may be provided between the protective layer and the photoconductive layer to prevent charge injection and an adhesive layer for enhancing adhesion.

As the conductive support, a conductor or an insulator subjected to a conductive treatment is used. For example, Al, Ag, Au on a metal or alloy such as Al, Ni, Fe, Cu, Au, or an insulating substrate such as polyester, polycarbonate, polyimide, or glass.
And a thin film of a conductive material such as In ₂ O ₃ , SnO ₂ or the like, or a paper subjected to a conductive treatment.

The shape of the conductive support is not particularly limited, and a plate, a drum, or a belt may be used as needed.

〔Example〕

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

Example 1 After pretreatment (washing) of an aluminum tube (120 mmφX480 mmL), the aluminum tube was set in a vacuum evaporation apparatus, and the resistance of the As ₂ Se ₃ alloy was adjusted to 60 μm on the support under the following conditions. Heat evaporation was performed to produce a photoconductive layer.

Deposition conditions Vacuum 3 × 10 ^-6 Torr Support temperature 200 ° C Boat temperature 450 ° C Next, a ligroin solution of silicone resin (AY42-441, manufactured by Toray Silicone Co., Ltd.) was dried on this photoconductive layer to a thickness of 0.2 μm. Thus, an intermediate layer was prepared.

Further, styrene / methacrylate / acrylic acid / N-methylolacrylamide resin liquid (solid content 40 wt.
%) 30 parts by weight, 18 parts by weight of tin oxide and an appropriate amount of a solvent were added, and a dispersion liquid dispersed in a ball mill for 100 hours was dip-coated, dried at 120 ° C. for 30 minutes, and a 5 μm protective layer was further provided. The surface of the protective layer was buff-polished under the following conditions to obtain an electrophotographic photosensitive member of the present invention.

[Buff polishing conditions]

Buff open cotton buff No.1 (manufactured by Koyosha) Buffing abrasive Liquid buffing abrasive No.132 (manufactured by Koyosha) Buffing peripheral speed 100m / min Rotating peripheral speed of photoconductor 30m / min Buffing cloth feed speed 1m / min Number of times of polishing 2 Example 2 An electrophotographic photoreceptor was produced in exactly the same manner as in Example 1 except that hub polishing was changed to superfinishing under the following processing conditions.

[Super finishing conditions]

Grinding wheel particle size # 5000 Vibration frequency of grinding wheel 1500C / min Pressure force of grinding wheel 0.05kg / cm ² Rotational peripheral speed of photoconductor 30m / min Feeding speed of grinding wheel 1m / min Polishing frequency 1 time Comparative example Polishing frequency was changed to 1 time A photoconductor for comparison was prepared in the same manner as in Example 1 except for the above.

Photoconductor of the present invention obtained as described above (Examples 1 and 2)
The contact angle with water was measured using a photoreceptor and a comparative photoconductor, and the residual potential was evaluated using a RICOH copier FT6550. Table 1 shows the results.

The results show that the photoreceptor of the present invention has a small residual potential and is excellent in durability.

[Effects] According to the present invention, a photosensitive member having lower residual potential and higher durability than a photosensitive member having a conventional protective layer can be obtained.

────────────────────────────────────────────────── (5) References JP-A-59-228252 (JP, A) JP-A-63-43162 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/00

Claims (1)

(57) [Claims] 1. A laminated photoreceptor comprising: a photoconductive layer on a conductive support; and a surface protective layer in which metal oxide particles are dispersed in a binder resin. The surface protective layer exposes the metal oxide on the surface. An electrophotographic photosensitive member having a contact angle with water of 80 ° or less.