EP0775942B1 - Elektrophotographisches, lichtempfindliches Element und es umfassende Prozesskassette und elektrophotographischer Apparat - Google Patents

Elektrophotographisches, lichtempfindliches Element und es umfassende Prozesskassette und elektrophotographischer Apparat Download PDF

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Publication number
EP0775942B1
EP0775942B1 EP19960308352 EP96308352A EP0775942B1 EP 0775942 B1 EP0775942 B1 EP 0775942B1 EP 19960308352 EP19960308352 EP 19960308352 EP 96308352 A EP96308352 A EP 96308352A EP 0775942 B1 EP0775942 B1 EP 0775942B1
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Prior art keywords
photosensitive member
electrophotographic photosensitive
resin
layer
electrophotographic
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English (en)
French (fr)
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EP0775942A1 (de
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Kazushige Nakamura
Akio Maruyama
Noriyuki Takagi
Michiyo Sekiya
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Canon Inc
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Canon Inc
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/147—Cover layers
    • G03G5/14704—Cover layers comprising inorganic material

Definitions

  • the present invention relates to an electrophotographic photosensitive member and, in particular, relates to an electrophotographic photosensitive member having a surface protective layer.
  • the present invention also relates to a process cartridge and an electrophotographic apparatus which have the foregoing electrophotographic photosensitive member.
  • the surface of an electrophotographic photosensitive member is required to be durable enough to withstand direct electrical or mechanical forces due to charging, light exposure, transferring, cleaning, and the like.
  • the practical durability is required to resist abrasion or flaws caused by contact with toner, paper, or cleaning members, and to resist deterioration due to the adhesion of active materials, such as ozone and NOx.
  • Japanese Patent Laid-Open No. 57-30846 discloses a surface protective layer comprising a resin and conductive metal-oxide particles.
  • zinc oxide, titanium oxide, and tin oxide which is doped with antimony oxide are proposed as a metal oxide for the surface protective layer.
  • Japanese Patent Laid-Open No. 57-30846 discloses a surface protective layer obtained by dispersing metal-oxide fine particles having an average diameter of 0.3 ⁇ m, which layer is substantially transparent with respect to visible light.
  • a large quantity of metal-oxide fine particles is required to achieve sufficient conductivity, thus resulting in insufficient transparency and a decrease in the strength of the surface protective layer.
  • an object of the present invention to provide an electrophotographic photosensitive member having a surface protective layer which exhibits excellent light transmittance and high conductivity, and a process cartridge and an electrophotographic apparatus which have the electrophotographic photosensitive member.
  • Another object of the present invention is to provide an electrophotographic photosensitive member which reliably provides high-quality images regardless of repeated use, and a process cartridge and an electrophotographic apparatus provided with the electrophotographic photosensitive member.
  • the present invention is an electrophotographic photosensitive member comprising a support, a photosensitive layer provided on the support, and a surface layer provided on the photosensitive layer, wherein the surface layer comprises tantalum-doped tin oxide particles and a resin.
  • the present invention includes a process cartridge and an electrophotographic apparatus which have the electrophotographic photosensitive member.
  • Fig. 1 shows an electrophotographic apparatus which has a process cartridge provided with an electrophotographic photosensitive member of the present invention.
  • the present invention is an electrophotographic photosensitive member comprising a support, a photosensitive layer provided on the support, and a surface layer provided on the photosensitive layer, wherein the surface layer comprises tantalum-doped tin oxide particles and a resin.
  • the tin oxide is doped with a tantalum compound in its crystal lattice.
  • the tantalum compound are tantalum, tantalum oxides, e. g., Ta 2 O 5 , and halogenated tantalum compounds, e. g., TaCl 5 .
  • tantalum oxides are more preferable, and Ta 2 O 5 is most preferable.
  • the preferable quantity of the doped tantalum compound is 1 to 50% by weight of the tin oxide and, more preferably, 2 to 20% by weight.
  • the above-mentioned tin oxide doped with tantalum can be prepared by a conventional doping method, such as alloying or diffusion.
  • the tin oxide doped with tantalum exhibits similar conductivity to tin oxide doped with antimony and indium oxide doped with tin oxide.
  • the resultant film attains similar transparency to a film containing dispersed zinc oxide and titanium oxide.
  • the resistivity of the tin oxide doped with tantalum is preferably 10 2 ⁇ cm or less. If it exceeds 10 2 ⁇ cm, the surface layer cannot easily attain the preferable conductivity.
  • the resistivity is measured according to the following method:
  • a disk-shaped pellet having a diameter of 4 cm and a thickness of 0.2 cm is prepared from a sample by applying pressure of 100 kg/cm 2 to the sample. Then, the resistivity ⁇ v ( ⁇ cm) of the pallet is measured by using a Hiresta AP apparatus (manufactured by Mitsubishi Petrochemical Corporation).
  • the average diameter of the primary particles of the tin oxide doped with tantalum is preferably 0.3 ⁇ m or less and, more preferably, 0.1 ⁇ m or less to provide further transparency for the layer.
  • the average diameter of the particles can be obtained by measuring diameters of a hundred particles chosen at random with the transmission electron microscope (TEM).
  • the surface layer of the present invention contains tin oxide doped with tantalum and a binder resin.
  • the preferable content of the tin oxide of the present invention is 40 to 85% by weight based on the total weight of the surface layer and, more preferably, 50 to 75% by weight. If the content is less than 40% by weight, sufficient conductivity is not readily achieved when the content exceeds 85% by weight, the mechanical strength of the layer becomes insufficient.
  • binder resin examples include a polycarbonate resin, a polyester resin, a polyarylate resin, a polystyrene resin, a polyethylene resin, a polypropylene resin, a polyurethane resin, an acrylic resin, an epoxy resin, a silicone resin, a cellulose resin, a polyvinyl chloride resin, a phosphazen resin, a melamine resin, a vinyl chloride-vinyl acetate copolymer, and the like. These binder resins may be used alone or in combination with others.
  • curable resins are preferably used because they are advantageous in hardness, abrasion resistance, particle dispersibility, and dispersion stability of the surface layer.
  • the protective layer is formed as follows: A coating liquid is prepared by dispersing tin oxide particles of the present invention in a solution which contains a thermo- or photo-setting monomer or oligomer, coating the dispersion on a photosensitive layer, drying the coated layer, and exposing the dried layer to heat or light so that the curable film is cured to form a protective layer.
  • the curable resin are acrylic, epoxy, phenol, and melamine resins.
  • the tin oxide particles may be surface-treated with a finishing agent for improving particle dispersibility and dispersion stability and also for preventing environmental changes which affect the resistance of the surface layer.
  • a finishing agent for improving particle dispersibility and dispersion stability and also for preventing environmental changes which affect the resistance of the surface layer.
  • Various kinds of silane coupling agents, silicone oils, siloxane compounds, surface active agents, and the like are employed as the finishing agent for the surface treatment. Fluoro-substituted finishing agents are preferred.
  • fluorine-containing compounds are preferably used as the finishing agents, because they are advantageous in tin oxide particle dispersibility and dispersion stability.
  • Non-limiting examples preferably used for the above-mentioned compounds will be given below.
  • fluorine-containing silane coupling agents are as follows: CF 3 CH 2 CH 2 Si (OCH 3 ) 3 , C 4 F 9 CH 2 CH 2 Si (OCH 3 ) 3 , C 6 F 13 CH 2 CH 2 Si (OCH 3 ) 3 , C 8 F 17 CH 2 CH 2 Si (OCH 3 ) 3 , C 8 F 17 CH 2 CH 2 Si (OCH 2 CH 2 OCH 3 ) 3 , C 10 F 21 Si (OCH 3 ) 3 , C 6 F 13 CONHSi (OCH 3 ) 3 , C 8 F 17 CONHSi (OCH 3 ) 3 , C 7 F 15 CONHCH 2 CH 2 CH 2 Si (OCH 3 ) 3 , C 7 F 15 CONHCH 2 CH 2 CH 2 Si (OC 2 H 5 ) 3 , C 7 F 15 COOCH 2 CH 2 CH 2 Si (OCH 3 ) 3 , C 7 F 15 COSCH 2 CH 2 CH 2 Si (OCH 3 ) 3 , C 8 F 17 SO 2 NH
  • fluorine-modified silicone oils are the compounds having the following formula: wherein R is -CH 2 CH 2 CF 3 , m and n are positive integers.
  • the surface treatment of the tin oxide particles of the present invention is conducted preferably as follows:
  • the tin oxide particles of the present invention and a finishing agent are mixed and dispersed in an appropriate solvent so that the finishing agent adheres to the surface of the particles.
  • the solvent is removed from the dispersion so as to fix the finishing agent to the particle surface.
  • a heat treatment may also be employed.
  • a catalyst may be added to the treatment solution for accelerating the reaction.
  • the resultant tin oxide particles may be further subjected to a pulverizing process, as needed.
  • the preferable content of the adhered finishing agent is 1 to 65% by weight based on the total weight of the tin oxide and, more preferably, 5 to 50% by weight, although the content may vary according to the size of the tin oxide particles.
  • fluorine-containing resin particles may be added to the surface protective layer for improving the separating properties, water-proofing, and surface smoothness of the layer.
  • a fluorine-containing resin employed for the particles are tetrafluoroethylene, trifluorochloroethylene, hexafluoropropylene, vinyl fluoride, vinylidene fluoride, and difluorodichloro ethylene resins, and copolymers thereof. These are used alone or combined with others, depending on the conditions. Among these, tetrafluoroethylene and vinylidene fluoride resins are particularly preferable.
  • the molecular weight and the size of the particles are not limited to certain values and may be selected according to ambient conditions.
  • the content of the fluorine-containing resin particles is preferably 70% or less by weight of the total weight of the surface layer and, more preferably, 10 to 60% by weight. If the content is more than 70% by weight, the mechanical strength of the resultant layer occasionally becomes insufficient.
  • the resistivity of the surface layer of the present invention is preferably 10 10 to 10 15 ⁇ cm and, more preferably, 10 11 to 10 14 ⁇ cm. If the resistivity is less than 10 10 ⁇ cm, it becomes difficult to retain the charge, resulting in image flow. When it is more than 10 15 ⁇ cm, the charge is not readily moved, resulting in light image and negative ghost.
  • the resistivity is measured according to the following method:
  • a 4- ⁇ m-thick (T) surface layer of the present invention is formed on comb-shaped platinum electrodes having an inter-electrode distance (D) of 180 ⁇ m and a length (L) of 5.9 cm. Then, a DC voltage (V) of 100 V is applied between the electrodes to measure the current value (I) by a pA (pico ampere). meter.
  • an additive such as the finishing agent or an anti-oxidant, may be added to the surface layer for improving the dispersibility, binding properties, weatherability, and the like.
  • the preferable thickness of the surface layer of the present invention is 0.2 to 10 ⁇ m and, more preferably, 0.5 to 6 ⁇ m.
  • Typical conductive materials include: a sheet- or drum-shaped metal, such as aluminum, an aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, or indium; plastic films laminated with metal foil, such as aluminum or copper foil; plastic films deposited with aluminum, indium oxide, tin oxide, or the like; and metals, plastic films, and paper on which a conductive material alone or combined with a binder resin is applied to make conductive layers.
  • a sheet- or drum-shaped metal such as aluminum, an aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, or indium
  • plastic films laminated with metal foil such as aluminum or copper foil
  • plastic films deposited with aluminum, indium oxide, tin oxide, or the like plastic films deposited with aluminum, indium oxide, tin oxide, or the like
  • metals, plastic films, and paper on which a conductive material alone or combined with a binder resin is applied
  • the support can be formed in the shape of a drum, sheet, belt, or the like, it is desirable to select the most suitable form to be used in the corresponding electrophotographic apparatuses.
  • the photosensitive layers are usually classified as monolayer types in which both a charge generation material and a charge transport material are mixed in the same layer or multilayer types which comprise a separate charge generation layer and a separate charge transport layer.
  • inorganic charge generation materials such as selenium, selenium-tellurium, and amorphous silicon
  • cationic dyes such as pyrilium, thiapyrilium, azulenium, thiacyanine, and quinocyanine dyes
  • squarium salt pigments such as pyrilium, thiapyrilium, azulenium, thiacyanine, and quinocyanine dyes
  • squarium salt pigments such as pyrilium, thiapyrilium, azulenium, thiacyanine, and quinocyanine dyes
  • squarium salt pigments such as pyrilium, thiapyrilium, azulenium, thiacyanine, and quinocyanine dyes
  • squarium salt pigments such as pyrilium, thiapyrilium, azulenium, thiacyanine, and quinocyanine dyes
  • squarium salt pigments such as pyrilium
  • a charge generation layer is obtained (i) as a deposition layer by vacuum-evaporating the foregoing materials or (ii) as a coated layer by applying and drying a coating liquid which is prepared by dispersing or dissolving the foregoing materials in a binder resin.
  • the binder resin is selected from various kinds of insulating resins and may be also selected from organic photoconductive polymers, such as poly-N-vinylcarbazole and polyvinyl pyrene.
  • organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinyl pyrene.
  • the binder resin are polyvinyl butyral, polyarylates (e. g., those which are obtained from copolycondensation of bisphenol A and phthalic acid), polycarbonates, polyesters, polyvinyl acetate, acrylic resins, polyacrylic amide, polyamides, cellulose resins, urethane resins, epoxy resins, and polyvinyl alcohol.
  • the binder resin is preferably contained in a charge generation layer in the amount of 80% or less by weight based on the total weight of the charge generation layer and, more preferably, 50% or less by weight.
  • the preferable thickness of the charge generation layer is 5 ⁇ m or less and more preferably, 0.01 to 1 ⁇ m.
  • a charge transport layer can be obtained by applying and drying a coating liquid which is prepared by dissolving a charge transport material in a binder resin.
  • the charge transport material are: polynuclear aromatic compounds of which the principal chain or the side chain has biphenylene, anthracene, pyrene, phenanthrene, and the like; nitrogen containing cyclic compounds, such as indole, carbazole, oxadiazole, and pyrazoline; hydrazone compounds and styryl compounds.
  • binder resin examples include: a polyarylate, polysulfone resin, polyamide resin, acrylic resin, acrylonitrile resin, methacrylate resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resins, polyester resin, alkyd resin, polycarbonate resin, polyurethane resin, and copolymers thereof, e. g., a styrene-butadiene copolymer, a styrene-acrylonitrile copolymer, and a styrene-maleate copolymer.
  • organic photoconductive polymers such as polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene can be used.
  • a binder resin Preferably, 100 parts by weight of a binder resin is used with 10 to 500 parts by weight of a charge transport material.
  • the thickness of the charge transport layer is preferably 5 to 40 ⁇ m and, more preferably, 10 to 30 ⁇ m.
  • a photosensitive layer of a monolayer type can be obtained by dispersing or dissolving the foregoing charge generation and charge transport materials in the foregoing binder resin to form a coating liquid and then applying the coating liquid to a support followed by drying.
  • an undercoating layer may be provided between the support and the photosensitive layer so as to work as a barrier and an adhesive between the layers.
  • the following materials can be used for the undercoating layer: polyvinyl alcohol, polyethylene oxide, nitrocellulose, ethylcellulose, methylcellulose, ethylene-acrylic copolymers, alcohol-soluble amides, polyamides, polyurethanes, casein, glue, gelatin, and the like.
  • the undercoating layer can be formed such that a solution prepared by dissolving the foregoing materials in an appropriate solvent is applied to a support followed by drying.
  • the thickness of the undercoating layer is preferably 5 ⁇ m or less and, more preferably, 0.2 ⁇ m to 3 ⁇ m.
  • the conductive layer can be obtained by dispersing carbon black and conductive powder, e. g. metal particles, in a binder resin to form a solution and applying the solution to a support followed by drying.
  • the thickness of the conductive layer is preferably 5 to 40 ⁇ m and, more preferably, 5 ⁇ m to 30 ⁇ m.
  • each of the layers mentioned above can be formed by a coating method, such as dip coating, spray coating, beam coating, spinner coating, roller coating, Meyer bar coating, or blade coating.
  • a coating method such as dip coating, spray coating, beam coating, spinner coating, roller coating, Meyer bar coating, or blade coating.
  • Fig. 1 shows a diagram of an electrophotographic apparatus which has a process cartridge provided with an electrophotographic photosensitive member of the present invention.
  • an electrostatic latent image is formed on the peripheral face of a drum-shaped electrophotographic photosensitive member 1 of the present invention.
  • the electrophotographic photosensitive member 1 is rotary-driven in the direction of the arrow around an axis 2.
  • the peripheral face of the electrophotographic photosensitive member 1 is uniformly charged to a predetermined positive or negative voltage by a primary charging means 3, and then subjected to image exposure light 4 from an image exposure means (not shown in the figure), such as slit exposure or laser-beam-scanning exposure.
  • the electrostatic latent image formed on the electrophotographic photosensitive member 1 is toner-developed by a developing means 5 and then, by a transfer means 6, transferred to a transfer medium 7 which is fed between the electrophotographic photosensitive member 1 and the transfer means 6 in synchronism with the rotation of the electrophotographic photosensitive member 1 from a feeding section (not shown in the figure).
  • the transfer medium 7 to which the image is transferred is separated from the surface of the electrophotographic photosensitive member 1, introduced into a image-fixing means 8 in which the image is fixed, and fed out from the apparatus as a copy.
  • the toner left on the surface of the electrophotographic photosensitive member 1 is cleaned by a cleaning means 9. Then, the electrophotographic photosensitive member 1 is subjected to pre-exposure light 10 from a pre-exposure means (not shown in the figure) to remove the charge so that it can be repeatedly used for image forming.
  • a contact-type means such as a charging roller, is employed as the primary charging means 3, pre-exposure is not always necessary.
  • a plurality of components among the above-mentioned electrophotographic photosensitive member 1, primary charging means 3, developing means 5, and cleaning means 9 may be integrated as a process cartridge which is detachable to a main body of an electrophotographic apparatus, such as a copying machine or a laser beam printer.
  • at least one of the primary charging means 3, developing means 5, and cleaning means 9 can be integrated with the electrophotographic photosensitive member 1 to form a process cartridge 11 which is supported as one body and detachable to a main body of an apparatus by utilizing guiding means, e. g., rails 12 of the main body.
  • An aluminum cylinder having a diameter of 30 mm and a length of 260 mm was used as a support.
  • a conductive layer 15 ⁇ m thick was formed by applying a solution having the following composition to the support by dip coating, followed by heating at 140°C for 30 min:
  • Ingredient Amount Conductive pigment: titanium oxide coated with tin oxide 10 parts
  • Resistance-regulating pigment titanium oxide 10 parts
  • Binder resin phenol resin 10 parts
  • Leveling agent silicone oil 0.001 part
  • Solvent: methanol/methylcellosolve 1/1 20 parts
  • the resultant solution was applied to the charge generation layer by dip coating followed by drying at 110°C for 1 hour to form a charge transport layer 18 ⁇ m in thickness.
  • the following materials were mixed and dispersed for 96 hours by a sand mill: 100 parts of Ta 2 O 5 -doped tin oxide particles, the primary particles of which had an average diameter of 0.02 ⁇ m and the resistivity of which was 2 x 10 1 ⁇ cm; 12 parts of 2,4-diethylthioxanthone, as an initiator for photopolymerization; 300 parts of toluene; and 60 parts of acrylic monomer having the following formula:
  • the resultant solution was applied to the charge transport layer by spray coating followed by drying. Next, ultraviolet radiation was applied for 20 seconds at 500 mW/cm 2 using a high-pressure mercury lamp to form a protective layer 4 ⁇ m thick.
  • the resistivity of a layer prepared according to the same method as this protective layer was 3 x 10 12 ⁇ cm, when measured by the above-mentioned manner.
  • An electrophotographic photosensitive member produced according-to the foregoing manner was stored at 23°C and at 45% RH (relative humidity) overnight. After storage, the electric potential of the member was measured using a laser beam printer LBP-NX (manufactured by Canon Inc.), as follows:
  • a developer unit and a cleaner were removed from a process cartridge of the laser beam printer, an electric-potential sensor was fixed to the position where the developer unit had been installed, and the photosensitive member of the process cartridge was replaced by the above-explained electrophotographic photosensitive member.
  • a transfer roller was removed from the main body of the printer and, after carrying out a solid black image mode (i. e., the entire surface was subjected to light exposure) electrophotographic process on 5 sheets of A4-size paper, the electric potential of the surface of the photosensitive member was measured and defined as VL. Then the electrophotographic photosensitive member was allowed to rotate 5 times under continuous laser exposure with the primary charging de-energized. The electric potential of the surface of the electrophotographic photosensitive member was measured again and defined as the residual electric potential (Vr).
  • An electrophotographic photosensitive member was produced and evaluated according to the same manner as in Example 1, except that the protective layer thereof was formed by the method as described below. The results are shown in Table 1.
  • the following materials were mixed and dispersed for 72 hours by a sand mill: 100 parts of Ta 2 O 5 -doped tin oxide particles-the primary particles of which had an average diameter of 0.02 ⁇ m and the resistivity of which was 2 x 10 1 ⁇ cm; 90 parts of a resol-type phenol resin having a solid content of 70% (trade name: Pli-O-Phen J-325, manufactured by Dainippon Ink and Chemicals, Incorporated), and 300 parts of methyl isobutyl ketone.
  • the resuling solution was applied to the charge transport layer by spray coating followed by heating at 140°C for 30 min. to form a protective layer 4 ⁇ m thick.
  • the resistivity of a layer prepared according to the same method as this protective layer was 5 x 10 ⁇ 13 ⁇ cm when measured by the above-mentioned manner.
  • An electrophotographic photosensitive member was prepared and evaluated according to the same manner as in Example 1, except that the protective layer thereof was formed by the method as described below. The results are shown in Table 1.
  • the following materials were mixed and dispersed for 72 hours by a sand mill: 100 parts of Ta 2 O 5 -doped tin-oxide particles-the primary particles of which had an average diameter of 0.02 ⁇ m and the resistivity of which was 2 x 10 1 ⁇ cm; 80 parts of a methyletherified melamine-formaldehyde resin (trade name: Symer 303, manufactured by Mitsui Cyanamid), 300 parts of ethanol, and 20 parts of bisphenol compound having the following formula:
  • the resulting solution was applied to the charge transport layer by dip coating followed by heating at 140°C for 2 hours to form a protective layer 4 ⁇ m thick.
  • the resistivity of a layer prepared according to the same method as this protective layer was 5 x 10 13 ⁇ cm when measured by the above-mentioned manner.
  • An electrophotographic photosensitive member was prepared and evaluated according to the same manner as Example 1, except that the thickness of the protective layer thereof was 6 ⁇ m. The results are shown in Table 1.
  • An electrophotographic photosensitive member was prepared and evaluated according to the same manner as in Example 1, except that the protective layer thereof was formed by the method as described below. The results are shown in Table 1.
  • the following materials were mixed and subjected to milling for 20 hours by a mill: 100 parts of Ta 2 O 5 -doped tin-oxide particles-the primary particles of which had an average diameter of 0.02 ⁇ m and the resistivity of which was 0.5 x 10 1 ⁇ cm; 20 parts of (3,3,3-trifluoropropyl)trimethoxysilane (manufactured by Chisso Corporation), and 300 parts of ethanol. The resulting solution was filtered, washed with ethanol, dried, and heated for 2 hours at 150°C so as to surface-treat the tin-oxide particles.
  • the resulting solution was applied to the charge transport layer by dip coating followed by drying and then ultraviolet radiation was applied for 20 seconds at 500 mW/cm 2 using a high-pressure mercury lamp to form a protective layer 4 ⁇ m thick.
  • the resistivity of a layer prepared according to the same method as this protective layer was 5 x 10 12 ⁇ cm when measured by the above-mentioned manner.
  • An photosensitive member was prepared and evaluated according to the same manner as in Example 1, except that the protective layer thereof was formed by the method as described below. The results are shown in Table 1.
  • the following materials were mixed and stirred for 48 hours by a stirring mill: 100 parts of Ta 2 O 5 -doped tin-oxide particles-the primary particles of which had an average diameter of 0.02 ⁇ m and the resistivity of which was 0.5 x 10 1 ⁇ cm; 15 parts of (3,3,3-trifluoropropyl)trimethoxysilane (manufactured by Chisso Corporation), and 300 parts of ethanol. The resultant solution was filtered, washed with ethanol, dried, and heated for 2 hours at 150°C so as to surface-treat the tin-oxide particles.
  • tetrafluoroethylene resin particles (trade name: Lublon L-2, manufactured by Daikin Industries, Ltd.) were mixed in the resulting solution and further dispersed by a sand mill for 4 hours.
  • the resulting solution was applied to the charge transport layer by dip coating followed by drying and then ultraviolet radiation was applied for 20 seconds at 500 mW/cm 2 using a highpressure mercury lamp to form a protective layer of 4 ⁇ m thick.
  • the resistivity of a layer prepared according to the same method as this protective layer was 1 x 10 13 ⁇ cm when measured by the above-mentioned manner.
  • An electrophotographic photosensitive member was prepared and evaluated according to the same manner as in Example 1, except that no protective layer was prepared.
  • An electrophotographic photosensitive member was prepared and evaluated according to the same manner as in Example 1, except that antimony-doped tin-oxide particles-the primary particles of which had an average diameter of 0.02 ⁇ m and the resistivity of which was 2 ⁇ cm were employed instead of the Ta 2 O 5 -doped tin oxide particles. The results are shown in Table 1.
  • the light transmittance of the protective layer was low, the absolute values of the initial VL and Vr were high, and the lines of the resultant images became narrower.
  • the absolute value of VL substantially decreased corresponding to an increase in shaving of the protective layer.
  • the resistivity of a layer prepared according to the same method as this protective layer was 1 x 10 12 ⁇ cm when measured by the above-mentioned manner.
  • An electrophotographic photosensitive member was prepared and evaluated according to the same manner as Example 1, except that tin-oxide-doped indium-oxide particles (trade name: ITO, manufactured by Mitsubishi Materials Corporation)-the primary particles of which had an average diameter of 0.03 ⁇ m and the resistivity of which was 0.1 x 10 1 ⁇ cm were employed instead of the Ta 2 O 5 -doped tin oxide particles.
  • ITO indium-oxide particles
  • the absolute value of VL substantially decreased corresponding to an increase in shaving of the protective layer.
  • the resistivity of a layer prepared according to the same method as this protective layer was 8 x 10 11 ⁇ cm when measured by the above-mentioned manner.
  • An electrophotographic photosensitive member was prepared and evaluated according to the same manner as in Example 1, except that titanium oxide particles-the primary particles of which had an average diameter of 0.03 ⁇ m and the resistivity of which was 6 x 10 2 ⁇ cm were employed instead of the Ta 2 O 5 -doped tin oxide particles. The results are shown in Table 1.
  • the resistivity of a layer prepared according to the same method as this protective layer was 1.5 x 10 15 ⁇ cm when measured by the above-mentioned manner.

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Claims (12)

  1. Elektrophotographisches lichtempfindliches Element, das einen Träger, eine auf dem Träger aufgebrachte lichtempfindliche Schicht und eine auf der lichtempfindlichen Schicht aufgebrachte Oberflächenschicht umfaßt, wobei die Oberflächenschicht mit Tantal dotierte Zinnoxidteilchen und ein Harz umfaßt.
  2. Elektrophotographisches lichtempfindliches Element nach Anspruch 1, wobei das Harz ein härtbares Harz ist.
  3. Elektrophotographisches lichtempfindliches Element nach Anspruch 1, wobei die mit Tantal dotierten Zinnoxidteilchen ein an der Oberfläche der Teilchen haftendes Mittel zur Oberflächenmodifikation einschließen.
  4. Elektrophotographisches lichtempfindliches Element nach Anspruch 3, wobei das Mittel zur Oberflächenmodifikation aus der Gruppe ausgewählt ist, die aus Silanhaftmitteln, Silikonölen, Siloxanverbindungen und grenzflächenaktiven Mitteln besteht.
  5. Elektrophotographisches lichtempfindliches Element nach Anspruch 4, wobei das Mittel zur Oberflächenmodifikation mit Fluor substituiert ist.
  6. Elektrophotographisches lichtempfindliches Element nach Anspruch 1, wobei die Oberflächenschicht desweiteren fluorhaltige Harzteilchen umfaßt.
  7. Elektrophotographisches lichtempfindliches Element nach Anspruch 1, wobei der spezifische elektrische Widerstand des mit Tantal dotierten Zinnoxids 102 Ω·cm oder weniger beträgt.
  8. Elektrophotographisches lichtempfindliches Element nach Anspruch 1, wobei der spezifische elektrische Widerstand der Oberflächenschicht 1010 bis 1015 Ω·cm beträgt.
  9. Elektrophotographisches lichtempfindliches Element nach Anspruch 1, wobei die Tantalverbindung, mit der das Zinnoxid dotiert wurde, ein Tantaloxid ist.
  10. Elektrophotographisches lichtempfindliches Element nach Anspruch 9, wobei das Tantaloxid Ta2O5 ist.
  11. Prozeßkasette, die (a) ein elektrophotographisches lichtempfindliches Element und (b) mindestens eine Einrichtung umfaßt, die aus der Gruppe ausgewählt ist, die aus einer Ladeeinrichtung, einer Entwicklungseinrichtung und einer Reinigungseinrichtung besteht;
    wobei (a) und (b) als ein eine Einheit bildender Körper enthalten sind und vom Hauptkörper eines elektrophotographischen Geräts abmontiert werden können; und
    wobei das elektrophotographische lichtempfindliche Element einen Träger, eine auf dem Träger aufgebrachte lichtempfindliche Schicht und eine auf der lichtempfindlichen Schicht aufgebrachte Oberflächenschicht umfaßt;
    wobei die Oberflächenschicht mit Tantal dotierte Zinnoxidteilchen und ein Harz umfaßt.
  12. Elektrophotographisches Gerät, das ein elektrophotographisches lichtempfindliches Element, eine Ladeeinrichtung, eine Belichtungseinrichtung, eine Entwicklungseinrichtung und eine Übertragungseinrichtung umfaßt,
    wobei das elektrophotographische lichtempfindliche Element einen Träger, eine auf dem Träger aufgebrachte lichtempfindliche Schicht und eine auf der lichtempfindlichen Schicht aufgebrachte Oberflächenschicht umfaßt;
    wobei die Oberflächenschicht mit Tantal dotierte Zinnoxidteilchen und ein Harz umfaßt.
EP19960308352 1995-11-24 1996-11-19 Elektrophotographisches, lichtempfindliches Element und es umfassende Prozesskassette und elektrophotographischer Apparat Expired - Lifetime EP0775942B1 (de)

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JP30549295 1995-11-24
JP305492/95 1995-11-24
JP30549295 1995-11-24

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US6492081B2 (en) * 2000-06-21 2002-12-10 Canon Kabushiki Kaisha Electrophotographic photosensitive member, and process cartridge and electrophotographic apparatus including the photosensitive member

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JPH0661004B2 (ja) * 1985-02-15 1994-08-10 ミノルタカメラ株式会社 感光体
JP2801664B2 (ja) * 1988-09-05 1998-09-21 株式会社リコー 電子写真感光体
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