JPH0728267A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To improve the lubricity of a surface layer and to improve the cleanability and wear resistance by adding a diamond fine particle to the surfae layer. CONSTITUTION:An org. photoconductive layer is provided on a substrate directly or through an intermediate layer, and further an org. protective layer is provided, if necessary, to constitute an electrophotographic photoreceptor. A diamond fine particle is dispersedly incorporated into the surface layer part of the outermost surface. When the conductive diamond fine particle is added into a protective layer, the particle acts as a lubricant and an electric resistance regulating agent. Since even a trace amt. of the diamond particle improves lubricity, the particle can be used in the charge transfer layer of a laminated photoreceptor without any protective layer, the lubricity is increased as the average diameter of the particles decreases. Besides, the fine particle is obtained by exploding trinitrotoluene in an inert gas atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in copying machines, printers and the like.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors used in copying machines, printers and the like are required to have durability against long-term use, especially abrasion resistance of the photoreceptor surface. Japanese Patent Laid-Open No. 61-116
Japanese Patent Laid-Open No. 362 proposes to improve the surface property by including a fluorine-containing block copolymer in the surface layer to improve the cleaning property and the abrasion resistance of the surface of the photoconductor. However, when it is attempted to include the fluorine-containing block copolymer in the surface layer, the fluorine-containing block copolymer migrates to the vicinity of the surface and concentrates near the surface during the surface layer formation process. The effect of the wear of the layer prematurely diminishes.

Japanese Patent Laid-Open No. 2-143257 proposes to incorporate polyethylene powder into the surface layer to lower the friction coefficient of the surface layer to improve the cleaning property and the abrasion resistance of the photoreceptor. . In addition, JP-A-2-14455
Japanese Unexamined Patent Publication No. 0 (1994) proposes to add fluorine-containing resin powder to the surface layer to improve the lubricity of the surface layer, improve the cleaning property, and improve the abrasion resistance of the photoconductor. However, when the resin powder is dispersed in the surface layer in this way to improve the abrasion resistance of the photosensitive layer surface, abnormal defects such as black spots and white spots may occur during image formation due to poor dispersion of the resin powder. Often occurs. Further, since the resin powder easily becomes a trap for the carrier at the time of forming a latent image, there arises a problem that the residual potential rises during repeated use and scumming occurs.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member which is free from the above-mentioned inconvenience, has improved surface properties of the surface layer portion, and is excellent in cleaning property and abrasion resistance. To provide.

[0005]

According to the present invention, an electrophotography comprising an organic photoconductive layer provided on a support directly or via an intermediate layer and, if necessary, further provided with an organic protective layer. There is proposed an electrophotographic photosensitive member characterized by including fine diamond particles dispersedly contained in the outermost surface layer of the photosensitive member.

As a result of various studies on the problem of surface abrasion of the electrophotographic photoreceptor, the present inventors have found that the addition of diamond fine particles to the surface layer improves the lubricity of the surface layer, thus improving the cleaning property and abrasion resistance. I found that it improved.
The diamond fine particles are a conductive substance, and when added to the protective layer, the diamond fine particles alone can serve as both the lubricity and the electric resistance adjusting agent. Further, since the diamond fine particles have the effect of improving the lubricity even in a very small amount, they can be used also in the charge transport layer of a laminated photoreceptor having no protective layer.

The smaller the average particle size of diamond fine particles, the greater the effect of improving the lubricity, and preferably 500 Å
The following is more preferable and 250 Å or less is preferable. If it exceeds 500 Å, lubricity becomes poor and cleaning failure is likely to occur.

The fine diamond particles can be obtained by exploding trinitrotoluene or the like in an inert gas atmosphere. When the content of the fine diamond particles is contained in the protective layer, the content thereof is 50 with respect to the binder resin of the protective layer.
Is preferably 130 to 130% by weight, more preferably 70 to 10%.
0 wt% is good. If it is less than 50% by weight, the residual potential is apt to rise and the background stain is liable to occur. On the other hand, when it exceeds 130% by weight, the electric resistance becomes small and the gradation becomes poor. When it is contained in the charge transport layer, it is preferably 0.05 to 1% by weight, more preferably 0.1 to 0.5% by weight, based on the binder resin of the charge transport layer. If it is less than 0.05% by weight, lubricity is poor and cleaning failure is likely to occur. On the other hand, if it exceeds 1% by weight, the charging property is deteriorated and the image density becomes insufficient.

The constituent materials other than diamond of the electrophotographic photosensitive member according to the present invention will be described below. The conductive substrate is intended to supply charges having a polarity opposite to that of the charged charges to the substrate side, has an electric resistivity of 10 ³ Ωcm or less, and has an intermediate layer, a charge generation layer and a charge transfer layer. Any material that can withstand the above film forming conditions can be used. Examples of these include electrically conductive metals and alloys such as Al, Ni, Cr, Zn, and stainless steel, inorganic insulating substances such as glass and ceramics, and organic insulation such as polyester, polyimide, phenol resin, nylon resin, and paper. Conductive treatment is performed by coating the surface of the conductive material with an electrically conductive material such as Al, Ni, Cr, Zn, stainless steel, carbon, SnO ₂ , In ₂ O ₃ by a method such as vacuum deposition, sputtering, and spray coating. And the like.

As the charge generating substance, for example, CI Pigment Blue 25 [CI (Color Index) 2
1180], CI Pigment Red 41 (CI21
100), CI Acid Red 52 (CI4510
0), CI Basic Red 3 (CI4521)
0), phthalocyanine pigments having a porphyrin skeleton, azulenium salt pigments, squaric salt pigments, anthanthansulon pigments, azo pigments having a carbazole skeleton (described in JP-A-53-95033),
Azo pigments having a stilbene skeleton (JP-A-53-138)
No. 229), an azo pigment having a triphenylamine skeleton (described in JP-A-53-132547), an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728), and oxadiene. Azo pigments having an azole skeleton (described in JP-A-54-12742), azo pigments having a fluorenone skeleton (described in JP-A-54-22834), azo pigments having a bisstilbene skeleton (JP-A-54). No. 17733), an azo pigment having a distyryl oxadiazole skeleton (described in JP-A No. 54-2129), a trisazo pigment having a distyryl carbazole skeleton (JP-A No. 54-129).
No. 17734), a trisazo pigment having a carbazole skeleton (described in JP-A-57-195767), and CIVAT BROWN 5 (CI734).
It is possible to use organic pigments such as 10), indigo-based pigments such as CI Avatar Dye (CI73030), and perylene-based pigments such as Argol Scarlet B and Indus Scarlet R (manufactured by Bayer).

Examples of the binder resin include polystyrene, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, polyester, polyarylate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. Polymer, polyvinyl acetate, polyvinylidene chloride, polyacrylate, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl acetal, polyvinyl benzal, polyvinyl formal, phenoxy resin, polyvinyl pyridine, poly-N-vinylcarbazole, acrylic Thermoplastic or thermosetting resin such as resin, silicone resin, nitrile rubber, chloroprene rubber, butadiene rubber, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin And the like. These binder resins may be used alone or as a mixture.

Examples of the solvent include benzene, toluene, xylene, methylene chloride, dichloroethane, monochlorobenzene, dichlorobenzene, ethyl alcohol, methyl alcohol, butyl alcohol, isopropyl alcohol, ethyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, cyclohexane. , Methyl cellosolve, ethyl cellosolve and the like, and these solvents can be used alone or in combination. The thickness of the charge generation layer is suitably about 0.05 to 2 μm, preferably 0.1 to 1 μm.

The charge-transporting layer is prepared by dissolving or dispersing the charge-transporting substance and the binder resin, and when the charge-transporting layer is the outermost surface, by dissolving or dispersing the diamond fine particles in a suitable solvent. Can be formed. Further, if necessary, a plasticizer, a leveling agent, an abrasion resistance enhancer, etc. can be added.

As the charge transport material, poly-N-carbazole and its derivative, poly-γ-carbazolylethylglutamate and its derivative, pyrene-formaldehyde condensate and its derivative, polyvinylpyrene, polyvinylphenanthrene, oxazole derivative and imidazole. Derivatives, triphenylamine derivatives, and JP-A-55-
154955, JP-A-55-156954, JP-A-55-52063, JP-A-56-81850, JP-A-51-10983, JP-A-51-94829, and JP-A-52-128373. JP-A-56-29245
JP-A-58-58552, JP-A-57-7307
5, JP-A-58-198043, JP-A-49-10.
5537, JP-A-52-139065, JP-A-52
The charge transport material described in each item of No. 139066 can be used. The binder resin and solvent in the charge transport layer may be the same as those used in the charge generation layer.

In the present invention, an undercoat layer may be provided between the conductive substrate and the charge generation layer. As the resin used for the undercoat layer, polyamide, vinyl chloride-vinyl acetate copolymer, casein, polyvinyl alcohol, polyvinyl acetal, polyvinyl benzal, polyacrylanilide, polyacrylate, polyhydroxymetaarylate, epoxy resin, phenol resin , Urethane resin and the like. These may be used alone or in combination. Further, these resins may be used in combination with a white pigment such as titanium oxide, tin oxide, zinc oxide, magnesium oxide, barium sulfate, lithopone and the like. The thickness of the undercoat layer is preferably 0.05 μm to 10 μm, more preferably 0.2 μm to 5 μm.

The intermediate layer provided between the protective layer and the charge transport layer is formed by dissolving the binder resin in a suitable solvent, applying this, and drying. The same binder resin and solvent as those used for the undercoat layer can be used. The protective layer is formed by dispersing or compatibilizing the diamond fine particles together with a binder resin in a suitable solvent, coating the intermediate layer with the fine particles, and drying. Examples of the binder resin include silicon resin, epoxy resin, urethane resin and melamine resin. These binder resins may be used alone or as a mixture.

[0017]

[Undercoat layer coating liquid]

Alkyd resin 3 parts by weight (Beckolite M-6401: Dainippon Ink and Chemicals, Inc.) Melamine resin 2 parts by weight (Super Beckamine G-821: Dainippon Ink and Chemicals, Inc.) Titanium oxide (CR-EL: Ishihara Sangyo) 30 parts by weight Methyl ethyl ketone 15 parts by weight was dispersed in a ball mill for 24 hours, followed by polyethylene glycol (PEG600S: Sanyo Kasei Co., Ltd.)
0.25 parts by weight was diluted with a dilute solution of methyl ethyl ketone / isopropyl alcohol = 10/10 parts by weight to obtain an undercoat layer coating solution. [Charge Generating Coating Liquid] Next, a cyclohexanone dispersion of an azo pigment of the following structural formula (Formula 1) is dip-coated on the undercoat layer and dried by heating to form a charge generating layer of about 0.2 μm. Formed.

[Chemical 1] [Coating Liquid for Charge Transport Layer] Next, a charge transport material (D) represented by the following structural formula (Formula 2), a polycarbonate (R) represented by the following structural formula (Formula 3) and an average particle size of 50Å Diamond fine particles (F), D / R / F = 70/1
00 / 0.3 (weight ratio), solid content concentration about 15% (solvent:
A liquid mixed so as to be methylene chloride was dispersed in a sand mill for 24 hours, and then silicon oil (KF-50:
Shin-Etsu Silicone Co., Ltd.) was added to the polycarbonate (R) in an amount of 0.02% by weight to prepare a coating liquid for the charge transport layer. This charge transport layer coating liquid is applied on the charge generation layer by dip coating,
It was dried by heating to form a charge generation layer of about 25 μm to prepare an electrophotographic photoreceptor.

[Chemical 2]

[Chemical 3]

Examples 2 to 7 The addition amount of diamond fine particles is 0.03, 0.05,
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 0.1, 0.5, and 1.2% by weight [ratio to polycarbonate (R)] was used.

Examples 8 to 10 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that diamond fine particles having an average particle size of 250, 500 and 1000Å were used.

Comparative Example 1 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that fine diamond particles were not added.

Comparative Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that polytetrafluoroethylene (Hostaflon: manufactured by Hoechst) was used in place of the diamond fine particles.

Comparative Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a fluorine-containing block copolymer (Modiper F-110: NOF CORPORATION) was used in place of the diamond fine particles.

The electrophotographic photosensitive member obtained as described above is a commercially available copying machine (Recopy FT4520: manufactured by Ricoh Company).
Installed in a modified machine that modified the cleaning part of so that the cleaning blade abuts in the counter direction.
All images were printed. The results are shown in Table 1.

[0024]

[Table 1] * 1: Polytetrafluoroethylene powder is used instead of diamond particles * 2: Fluorine-containing block copolymer is used instead of diamond particles

Example 11 An undercoat layer was prepared in the same manner as in Example 1, and a cyclohexanone dispersion of an azo pigment of the following structural formula (Formula 4) was dip-coated on this undercoat layer and dried by heating. A charge generation layer of about 0.2 μm was formed.

[Chemical 4] Next, the charge transporting material (D ') represented by the following structural formula (Formula 5) and the polycarbonate resin (R) represented by the structural formula (Formula 3) are combined with each other to obtain D' / R = 9/10 (weight). Ratio) and a solid content concentration of about 15% (solvent: methylene chloride), and then add 0.02% by weight of silicone oil (KF-50: manufactured by Shin-Etsu Silicone Co., Ltd.) to the polycarbonate resin (R). The charge transport layer coating solution was applied onto the charge generation layer by dip coating and dried by heating to form a charge generation layer having a thickness of about 28 μm to prepare an electrophotographic photoreceptor.

[Chemical 5] Next, 0.4 part by weight of polyamide (CM800: manufactured by Toray Industries, Inc.) was dissolved in a solvent of methanol / 1-butanol = 7/3 (weight ratio), and an intermediate layer coating solution was spray-coated on the charge transport layer. Then, it was dried by heating to form an intermediate layer of about 0.3 μm.

Next, styrene / methyl methacrylate /
2-hydroxyethyl methacrylate = 10/40/5
0 (weight ratio) of copolymer resin 120 parts by weight, average particle size 5
150 parts by weight of 0Å diamond particles and toluene /
Cellosolve acetate / methyl isobutyl ketone = 3 /
850 parts by weight of a mixed solvent of 4/3 (weight ratio) is added to 48
After being dispersed in a sand mill for a period of time, the mill base, the dilute resin solution of the coating liquid for the undercoat layer of Example 1 and the trimethylolpropane adduct of hexamethylene diisocyanate (Sumijour HT: manufactured by Sumitomo Bayer Co., Ltd.) were added to the coating liquid. The diamond fine particles were mixed at a weight ratio of 75% by weight to the resin, and the isocyanate group and the number of hydroxyl groups were mixed at a ratio of 1: 1 to prepare a protective layer coating solution. This protective layer coating solution was spray coated on the intermediate layer and dried by heating to form a protective layer of about 5 μm to obtain an electrophotographic photoreceptor.

Examples 12 to 16 The amount of diamond fine particles added was changed with respect to the resin of the protective layer.
An electrophotographic photosensitive member was produced in the same manner as in Example 11 except that the amount was 40, 60, 90, 120, and 140% by weight.

Examples 17 to 19 Electrophotographic photosensitive members were prepared in the same manner as in Example 11 except that diamond fine particles having an average particle size of 250, 500 and 1000Å were used.

Comparative Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 11 except that tin oxide (manufactured by Mitsubishi Materials Corporation) was used instead of diamond fine particles.

Comparative Example 5 An electrophotographic photosensitive member was prepared in the same manner as Comparative Example 4 except that 20% by weight of polytetrafluoroethylene (phosphlon: manufactured by Hoechst) was added to the binder resin of the protective layer.

The electrophotographic photosensitive member obtained as described above was mounted on a remodeling machine so that the cleaning section of a commercially available copying machine (Imagio MF530: manufactured by Ricoh) was remodeled so that the cleaning blade abuts in the counter direction. 50,000 images were printed. The results are shown in Table 2.

[Table 2] * 3: Use tin oxide instead of diamond particles * 4: Use tin oxide + polytetrafluoroethylene powder instead of diamond particles

[0032]

By adding diamond fine particles to the surface layer, the lubricity of the surface layer is improved, and as a result, an electrophotographic photoreceptor having excellent cleaning properties and abrasion resistance can be obtained.

Claims (1)

[Claims] 1. An electrophotographic photosensitive member comprising an organic photoconductive layer provided on a support directly or via an intermediate layer, and an organic protective layer if necessary, on the outermost surface layer portion. An electrophotographic photosensitive member characterized by containing fine diamond particles dispersed therein.