JP2009186642A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor free from scratches and cracks on a protective layer and free from transfer memory even when the photoreceptor is used for printing a great number of sheets (for example, 750,000 sheets). <P>SOLUTION: The electrophotographic photoreceptor having at least a substrate, an organic photosensitive layer and a protective layer is characterized in that the protective layer has a hardness of 2 to 7 GPa measured by a nano-indentation method and an ozone permeability of ≤10%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic photoreceptor.

  An electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor) is required to have required sensitivity, electrical characteristics, and optical characteristics according to the electrophotographic process used. Furthermore, in a photoreceptor that is used repeatedly over and over, the protective layer of the photoreceptor, that is, the layer farthest from the substrate, has electrical and mechanical external forces such as charging, exposure, development, transfer, and cleaning. Durability against them is required to be added directly. Specifically, durability against surface abrasion and scratches due to rubbing, ozone generated at the time of charging, deterioration caused by nitrogen oxides, etc. is required. On the other hand, there is also a problem that toner adheres to the protective layer surface due to repeated development with toner and cleaning with a cleaning blade, and foreign matter is deposited, and it is also required to improve the cleaning property of the protective layer. .

  In many cases, the durability of the photoreceptor is governed by deterioration of the potential characteristics due to wear of the protective layer and image defects due to scratches on the surface of the protective layer.

  For the purpose of improving durability against film abrasion and scratches, a method is disclosed in which a protective layer using a curable compound is provided on the surface of the photoreceptor to improve the film strength (see, for example, Patent Documents 1 to 3). .

The photoreceptor having the protective layer using the curable compound disclosed above significantly reduces the occurrence of wear and scratches and achieves high durability in terms of film strength.
JP-A-6-308766 Japanese Patent Laid-Open No. 6-282092 JP-A-5-173350

  However, the film strength is improved in a photoconductor using a curable compound, particularly a photo-radical curable compound as a constituent member of a protective layer, but there is a problem that a transfer memory is generated when a large number of sheets are printed. .

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member that does not generate scratches or cracks in a protective layer and does not generate a transfer memory even when a large number of sheets (for example, 750,000 sheets) are printed.

  The present invention is achieved by adopting the following configuration.

1. In an electrophotographic photoreceptor comprising at least a substrate, an organic photosensitive layer and a protective layer,
The hardness measured by the nanoindentation method of the protective layer is 2-7 GPa,
An electrophotographic photoreceptor having an ozone transmittance of 10% or less.

  2. 2. The electrophotographic photosensitive member according to 1 above, wherein the protective layer is formed by an atmospheric pressure plasma CVD method.

  The photoreceptor of the present invention has an excellent effect that no transfer memory is generated without causing scratches or cracks in the protective layer even when a large number of sheets (for example, 750,000 sheets) are printed.

  It is possible to provide a protective layer with very little wear on the surface of the photoconductor by deposition means such as atmospheric pressure plasma CVD (AGP), but the obtained photoconductor is transferred relatively early when a large number of sheets are printed. There was a problem that memory was generated.

  In the present invention, the transfer memory means that when a solid black and solid white mixed image is continuously printed, and then a uniform halftone image is printed, the solid black and solid white are included in the halftone image. This means that a history appears (memory generation).

  Occurrence of the transfer memory was thought to be due to oxidation of the protective layer and adhesion of oxides. However, as a result of experiments, the active layer (specifically, ozone) generated from the strip electrode deteriorates the charge transport material. It was found that it was caused by accumulation and progressing just below the interface of the charge transport layer.

  The present inventors have considered and considered that it is essential to provide the protective layer with gas barrier performance and wear resistance higher than those in the past in order to prevent deterioration of the charge transport material directly under the protective layer.

  The present inventors have made various studies in order to solve the above problems.

  As a result of various studies, by providing a protective layer with a hardness of 2 to 7 GPa and an ozone transmittance of 10% or less on the surface of the photoreceptor, even if a large number of sheets (for example, 750,000 sheets) are printed, It has been found that a photoconductor can be obtained in which there is little cracking and no transfer memory is generated.

  Specifically, the surface of the photosensitive member can be prevented from being worn or scratched even if it is repeatedly printed by setting the hardness by the nanoindentation method to 2 GPa or more by the protective layer. It is presumed that cracking can be prevented. In addition, it is presumed that the ozone transport rate is 10% or less, which prevents the charge transport material immediately below the protective layer from being decomposed by ozone gas generated from the discharge wire during charging. It is speculated that when the charge transport material directly under the protective layer is decomposed, the decomposed material becomes a charge trap and a transfer memory is generated.

  The method of forming a protective layer having a protective layer hardness of 2 to 7 GPa measured by the nanoindentation method and an ozone transmittance of 10% or less is not particularly limited. For example, an active gas such as ozone is formed on the protective layer film. An atmospheric pressure plasma CVD method in which there is no defect that allows a hardness to pass through and a hardness of 2 to 7 GPa can be obtained.

  Hereinafter, the present invention will be described in detail.

  First, a method for measuring the ozone transmittance of the protective layer and a method for measuring the hardness of the protective layer will be described.

<Measurement of ozone permeability of protective layer>
The ozone transmittance of the protective layer according to the present invention is 10% or less.

  In the present invention, the ozone transmittance of the protective layer is evaluated by the difference in the intensity of fluorescence emitted by the charge transport material before and after leaving the photoconductor having the protective layer in a constant ozone gas for a predetermined time.

  In addition, fluorescence intensity can be performed using a well-known measuring apparatus.

In particular,
1. Measure fluorescence intensity of photoconductor with protective layer (A)
2. The protective layer is removed by etching or polishing, and the fluorescence intensity is measured when ozone gas (containing 200 ppm of ozone in the air) is exposed to the sample from which the charge transport layer containing the charge transport material is exposed (B). )
3. Measure the fluorescence intensity when ozone gas (containing 200 ppm of ozone in the air) is exposed to a photoreceptor having a protective layer for 1 hour (C)
4). Ozone permeability = C / (A−B) × 100
<Measurement of hardness of protective layer>
The hardness when measured by the nanoindentation method of the protective layer is 2 to 7 GPa.

  By setting the hardness of the protective layer to 2 GPa or more, it is possible to prevent scratches from occurring. Moreover, it can prevent that a crack generate | occur | produces by the hardness of a protective layer being 7 GPa or less.

  The hardness of the protective layer by the nanoindentation method is a value obtained by directly measuring the surface of the protective layer.

  The hardness measurement method by the nanoindentation method is a method of measuring the relationship between the load and the indentation depth (displacement amount) while pushing a minute diamond indenter into the thin film, and calculating the hardness from the measured value.

  FIG. 1 is a schematic diagram showing an example of a measuring apparatus for measuring hardness by a nanoindentation method.

  In FIG. 1, 31 is a transducer, 32 is an equilateral triangular diamond Berkovich indenter, 1 is a photoreceptor, 11 is a substrate, 13 is a photosensitive layer, and 16 is a protective layer.

  This measuring apparatus can measure the displacement with nanometer accuracy using a transducer 31 and a diamond Berkovich indenter 32 while applying a load of μN order. For this measurement, commercially available “NANO Indenter XP / DCM” (manufactured by MTS Systems / MST NANO Instruments) can be used.

  FIG. 2 is a schematic diagram showing a state where the indenter is in contact with the sample.

  The hardness H is obtained from the following formula (1).

Formula (1)
H = Pmax / A
Here, P is the maximum load applied to the indenter, and A is the contact projected area between the indenter and the sample at that time.

  The contact projection area A can be expressed by the following formula (2) using hc in FIG.

Formula (2)
A = 24.5hc ²
Here, hc becomes shallower than the entire indentation depth h due to the elastic dent on the peripheral surface of the contact point as shown in FIG. 2, and is expressed by the following formula (3).

Formula (3)
hc = h−hs
Here, hs is the amount of indentation due to elasticity, and the following equation (4) is obtained from the gradient of the load curve after the indenter is pushed (gradient S in FIG. 4) and the shape of the indenter.
Formula (4)
hs = ε × P / S
It is expressed.

  Here, ε is a constant related to the shape of the indenter, and is 0.75 in the Berkovich indenter.

  Using such a measuring device, the hardness of the surface of the protective layer and the charge transport layer can be measured.

Measurement conditions Measuring instrument: NANO Indenter XP / DCM (manufactured by MTS Systems)
Measuring indenter: Diamond Berkovich indenter with a regular triangular tip Measurement environment: 20 ° C., 60% RH
Measurement sample: Cut the photoconductor to a size of 5 cm × 5 cm to prepare a measurement sample Maximum load setting: 25 μN
Indentation speed: A speed that reaches a maximum load of 25 μN in 5 seconds, and a load is applied in proportion to the time. In addition, each sample is measured at 10 points at random, and the average value is the hardness measured by the nanoindentation method. .

  Next, the layer structure of the photoreceptor will be described.

"Layer structure"
The photoreceptor of the present invention is obtained by providing a photosensitive layer on a substrate and further providing a protective layer thereon. In order to improve the adhesion between the substrate and the photosensitive layer, an intermediate layer can be provided between the substrate and the photosensitive layer.

  FIG. 3 is a schematic view showing an example of the layer structure of the photoreceptor of the present invention.

  In FIG. 3, 1 is a photoreceptor, 11 is a substrate, 12 is an intermediate layer, 13 is a photosensitive layer, 14 is a charge generation layer, 15 is a charge transport layer, and 16 is a protective layer.

  FIG. 3A is a schematic view of a photoreceptor produced by providing the photosensitive layer 13 and the protective layer 16 on the outer periphery of the substrate 11.

  FIG. 3B is a schematic view of a photoreceptor produced by providing a charge generation layer 14, a charge transport layer 15, and a protective layer 16 on the outer periphery of the substrate 11.

  FIG. 3C is a schematic view of a photoconductor produced by providing the intermediate layer 12 on the outer periphery of the substrate 11, and providing the charge generation layer 14, the charge transport layer 15, and the protective layer 16 thereon.

  Among these, the structure shown in FIG. 3C is preferable because the adhesion between the substrate and the photosensitive layer becomes better.

《Protective layer》
The protective layer according to the present invention is formed on a photosensitive layer (specifically, a charge transport layer) provided on the outer periphery of the substrate.

  The protective layer according to the present invention has a specific hardness and a gas barrier property. Specifically, a protective layer made of a metal oxide film such as silicon oxide, silicon oxynitride, silicon nitride, titanium oxide, titanium oxynitride, titanium nitride, or aluminum oxide is provided on the charge transport layer.

  Among these, a silicon oxide film that can form a uniform film and can satisfy specific hardness and gas barrier properties is preferable. A film made of a mixture thereof is also preferable.

  The protective layer in the present invention may be at least one layer. The protective layer preferably has a structure in which the hardness gradually increases from directly above the charge transport layer toward the surface of the protective layer farthest from the charge transport layer.

(Protective layer thickness)
The thickness of the protective layer is not particularly limited as long as hardness and absorbance can be satisfied, preferably 10 to 500 nm, more preferably 20 to 400 nm.

  The film thickness of the protective layer is a value obtained by measurement using “MXP21 (manufactured by Mac Science)”. A specific measurement of the film thickness can be performed by the following method.

  Copper is used as the target of the X-ray source and it is operated at 42 kV and 500 mA. A multilayer parabolic mirror is used for the incident monochromator. The incident slit is 0.05 mm × 5 mm, and the light receiving slit is 0.03 mm × 20 mm. Measurement is performed by the FT method with a step width of 0.005 ° and a step of 10 seconds from 0 to 5 ° in the 2θ / θ scan method. With respect to the obtained reflectance curve, Reflectivity Analysis Program Ver. 1 is used to perform curve fitting, and each parameter is obtained so that the residual sum of squares of the actually measured value and the fitting curve is minimized. The film thickness of the laminated film is obtained from each parameter.

  When the thickness of the protective layer is 10 nm or more, durability and surface strength are satisfactory, scratches do not occur due to transfer to cardboard, etc., and the thin film eventually wears unevenly, resulting in a decrease in transfer rate and uneven transfer. Is less likely to occur. When the thickness is 1000 nm or less, adhesion and bending resistance are not insufficient, and even when a large number of sheets are used, cracking and peeling are less likely to occur, and the time required for film formation is small, which is preferable from the viewpoint of production.

  Next, production of the photoreceptor will be described.

<< Production of photoconductor >>
The photoreceptor of the present invention has the layer structure shown in FIG.

  Hereinafter, an example of a method for producing a photoreceptor (FIG. 3C) in which an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer are provided in this order on the outer periphery of the substrate will be described. The invention is not limited to this.

(Substrate)
As the substrate of the photoreceptor, a conductive drum or a seamless belt can be used.

  The base material used in the present invention may be any material as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or seamless belt, aluminum Metal foil such as copper or copper laminated on plastic film, aluminum, indium oxide or tin oxide deposited on plastic film, metal or plastic with conductive layer applied alone or with binder resin Examples include film and paper.

(Middle layer)
In the present invention, an intermediate layer having a barrier function and an adhesive function may be provided between the substrate and the photosensitive layer. The intermediate layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, gelatin and the like. Of these, an alcohol-soluble polyamide is preferable. The film thickness of the intermediate layer is preferably 0.1 to 15 μm.

  Various conductive fine particles and metal oxides can be contained for the purpose of adjusting the electric resistance of the intermediate layer. For example, various metal oxides such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used. You may use these metal oxides 1 type or in mixture of 2 or more types. When two or more types are mixed, they may take the form of a solid solution or fusion. The average particle diameter of such a metal oxide is preferably 0.3 μm or less, more preferably 0.1 μm or less.

(Charge generation layer)
The charge generation layer is composed of azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as bilenquinone and anthanthrone, pyranthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and charge generation materials such as phthalocyanine pigments alone, Or it forms by apply | coating and drying the coating liquid disperse | distributed in the well-known binder resin. As the binder resin, a formal resin, a butyral resin, a silicone resin, a silicone-modified butyral resin, a phenoxy resin, polystyrene, polyvinyl acetate, an acrylic resin, and the like are desirable.

  The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. The film thickness of such a resin-dispersed charge generation layer is preferably 5 μm or less, more preferably 0.05 to 3 μm. Incidentally, the coating solution for the charge generation layer can prevent the occurrence of image defects by filtering foreign matter and aggregates before coating.

(Charge transport layer)
The charge transport layer is formed by coating and drying a coating solution in which a charge transport material and a binder resin are mainly dissolved in a solvent. Examples of the charge transport material include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds.

  These are combined with 0.5 to 2 times the amount of binder resin to produce a coating solution. Examples of the binder resin include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin. And a copolymer resin containing two or more of the repeating unit structures of these resins. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used.

  The charge transport layer preferably contains an antioxidant. A representative example of the antioxidant is a substance having a property of preventing or suppressing the action of oxygen under conditions of light, heat, discharge, etc., against an auto-oxidizing substance present in the photoreceptor. It is.

  The thickness of the charge transport layer is preferably 5 to 40 μm, and more preferably 15 to 30 μm.

(Protective layer)
The protective layer can be formed by an atmospheric pressure plasma CVD method.

  Hereinafter, the manufacturing apparatus and manufacturing method formed by the atmospheric pressure plasma CVD method, and the gas used for manufacturing will be described.

  FIG. 4 is an explanatory view of a first manufacturing apparatus for manufacturing the protective layer of the photoreceptor.

  The production apparatus and production method for forming the protective layer according to the present invention by plasma CVD and the gas used for production will be described in detail.

  FIG. 4 is an explanatory diagram of a first manufacturing apparatus for manufacturing a protective layer.

  In FIG. 4, 10 is a substrate provided with at least a photosensitive layer on the outer periphery of the substrate (hereinafter also referred to as photoreceptor A), 3 is a plasma CVD apparatus, 20 is an electrode, 21 is a fixed electrode, 23 is a discharge space, and G is a mixture. Gas, 24 is a mixed gas supply device, 29 is a discharge vessel, 25 is a first power source, 25a is a first filter, 26 is a second power source, 26a is a second filter, G1 is an excited mixed gas, G 'Indicates used exhaust gas, and 28 indicates an exhaust part.

  The plasma CVD apparatus 3 forms a protective layer on the charge transport layer, and is a film forming apparatus that forms the protective layer on the surface of the photoconductor A10 using the photoconductor A10 rotating in the direction of the arrow as the electrode 20.

  The plasma CVD apparatus 3 includes at least one fixed electrode 21 arranged along the outer periphery of the electrode 20 having the photoreceptor A10 as an electrode, and a discharge space 23 in which discharge is performed in a region where the fixed electrode 21 and the electrode 20 face each other. A mixed gas supply device 24 that mixes at least the raw material gas and the discharge gas and supplies the mixed gas G to the discharge space 23, a discharge vessel 29 that reduces the inflow of air into the discharge space 23, and the photoconductor A10. A second power source 26 connected to the first electrode 25, a first power source 25 connected to the fixed electrode 21, and an exhaust unit 28 for exhausting the used exhaust gas G ′.

  The mixed gas supply device 24 supplies, to the discharge space 23, a mixed gas obtained by mixing a raw material gas for forming a protective layer and a discharge gas such as nitrogen gas or argon gas.

  The first power supply 26 outputs a voltage having a frequency ω1, the second power supply 25 outputs a voltage having a frequency ω2, and generates an electric field V in which the frequencies ω1 and ω2 are superimposed on the discharge space 23 by these voltages. . Then, the mixed gas G is turned into plasma by the electric field V to be an excited mixed gas G1, and a film (protective layer) corresponding to the source gas contained in the mixed gas G is deposited on the surface of the charge transport layer.

  As described above, the photoconductor A is the electrode 20, and at least one pair of fixed electrodes as the other electrode is provided along the outside of the photoconductor A, and an electric field is applied between these electrodes at or near atmospheric pressure. A plasma discharge is generated and a film is deposited and formed on the surface of the charge transport layer.

  As still another form, one of the electrodes of the photoreceptor A and the fixed electrode may be connected to the ground, and a power source may be connected to the other electrode. In this case, it is preferable to use the second power source 25 as the power source because a dense film can be formed, and particularly when a discharge gas such as argon is used as the discharge gas.

  FIG. 5 is an explanatory diagram of a second manufacturing apparatus for manufacturing a protective layer.

  In FIG. 5, 10 is a photoconductor A, 4 is a plasma CVD apparatus, 21a is a fixed electrode connected to a first power source, 21b is a fixed electrode connected to a second power source, 23a is a discharge space, and G is a mixing device. Gas, G2 is an excited mixed gas, 24 is a mixed gas supply device, 29 is a discharge vessel, 25 is a first power source, 25a is a first filter, 26 is a second power source, 26a is a second filter, G ′ is used exhaust gas, and 28 is an exhaust part.

  The plasma CVD apparatus 4 forms a protective layer on the surface of the photoreceptor A10, and is a film forming apparatus that forms a protective layer on the surface of the photoreceptor A10 that rotates in the direction of the arrow.

  The plasma CVD apparatus 4 is different from the plasma CVD apparatus 3 described above in connection with the connection of the power supply to the electrodes, the supply of the mixed gas, and the deposition of the film.

  The plasma CVD apparatus 4 has at least one pair of fixed electrodes arranged along the outer periphery of the photoconductor A10, and is fixed to the fixed electrode 21a connected to the first power supply 25 and the second power supply 26. A discharge space 23a in which discharge is performed in a region facing the electrode 21b, a mixed gas supply device 24 that generates a mixed gas G of at least a raw material gas and a discharge gas and supplies the mixed gas G to the discharge space 23a, and a discharge space A discharge vessel 29 that reduces the inflow of air into the gas generator 23a, the first power source 25 connected to the fixed electrode 21a, the second power source 26 connected to the fixed electrode 21b, and the used exhaust gas G ′. And an exhaust part 28 for exhausting the air.

  The mixed gas supply device 24 supplies, to the discharge space 23a, a mixed gas obtained by mixing a raw material gas for forming a protective layer and a discharge gas such as nitrogen gas or argon gas.

  The first power supply 25 outputs a voltage having a frequency ω1, the second power supply 26 outputs a voltage having a frequency ω2 higher than the frequency ω1, and the electric field in which the frequencies ω1 and ω2 are superimposed on the discharge space 23a by these voltages. V is generated. Then, the mixed gas G is turned into plasma by the electric field V to become an excited mixed gas G2, and the excited mixed gas G2 is jetted to the film forming region 41 and jetted onto the surface of the photoreceptor A10. A film corresponding to the source gas contained in G2 is deposited and formed on the surface of the charge transport layer.

  As still another form, one fixed electrode of a pair of fixed electrodes may be connected to the ground, and the power source may be connected to the other fixed electrode. As the power source in this case, it is preferable to use the second power source because a dense thin film can be formed, and particularly preferable when a discharge gas such as argon is used as the discharge gas.

  FIG. 6 is an explanatory diagram of a third manufacturing apparatus for manufacturing a protective layer.

  FIG. 6 is an apparatus in which a mixed gas supply apparatus is added to the second manufacturing film apparatus of FIG. 5, and a thin film can be formed simultaneously using a large number of mixed gases.

  The discharge gas according to the present invention refers to a gas that is plasma-excited under the above conditions, and examples thereof include nitrogen, argon, helium, neon, krypton, xenon, and mixtures thereof.

  As a raw material gas for forming the protective layer, an organic metal compound that is gaseous or liquid at room temperature, particularly an alkyl metal compound, a metal alkoxide compound, or an organometallic complex compound is used. The phase state of these raw materials does not necessarily need to be a gas phase at normal temperature and normal pressure, and may be solid even in a liquid phase as long as it can be vaporized through heating, decompression, etc. through melting, evaporation, sublimation, etc. It can also be used in phases.

  The source gas contains a component that is in a plasma state in the discharge space and forms a thin film, and is an organometallic compound, an organic compound, an inorganic compound, or the like.

  For example, as a silicon compound, silane, tetramethoxysilane, tetraethoxysilane (TEOS), tetra n-propoxysilane, tetraisopropoxysilane, tetra n-butoxysilane, tetra t-butoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane , Diethyldimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, phenyltriethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, hexamethyldisiloxane, bis (dimethylamino) dimethyl Silane, bis (dimethylamino) methylvinylsilane, bis (ethylamino) dimethylsilane, N, O-bis (trimethylsilyl) acetamide, bis (trimethylsilyl) carbodiimi , Diethylaminotrimethylsilane, dimethylaminodimethylsilane, hexamethyldisilazane, hexamethylcyclotrisilazane, heptamethyldisilazane, nonamethyltrisilazane, octamethylcyclotetrasilazane, tetrakisdimethylaminosilane, tetraisocyanatosilane, tetramethyldisilazane , Tris (dimethylamino) silane, triethoxyfluorosilane, allyldimethylsilane, allyltrimethylsilane, benzyltrimethylsilane, bis (trimethylsilyl) acetylene, 1,4-bistrimethylsilyl-1,3-butadiyne, di-t-butylsilane, 1,3-disilabutane, bis (trimethylsilyl) methane, cyclopentadienyltrimethylsilane, phenyldimethylsilane, phenyltrimethylsila , Propargyltrimethylsilane, tetramethylsilane, trimethylsilylacetylene, 1- (trimethylsilyl) -1-propyne, tris (trimethylsilyl) methane, tris (trimethylsilyl) silane, vinyltrimethylsilane, hexamethyldisilane, octamethylcyclotetrasiloxane, tetramethyl Examples include, but are not limited to, cyclotetrasiloxane, hexamethylcyclotetrasiloxane, M silicate 51, and the like.

  Titanium compounds include organometallic compounds such as tetradimethylaminotitanium, metal hydrogen compounds such as monotitanium and dititanium, metal halogen compounds such as titanium dichloride, titanium trichloride, and titanium tetrachloride, tetraethoxy titanium, tetraisopropoxy titanium And metal alkoxides such as tetrabutoxytitanium, but are not limited thereto.

  As aluminum compounds, aluminum n-butoxide, aluminum s-butoxide, aluminum t-butoxide, aluminum diisopropoxide ethyl acetoacetate, aluminum ethoxide, aluminum hexafluoropentanedionate, aluminum isopropoxide, 4-pentanedionate Dimethylaluminum chloride and the like, but are not limited thereto.

  These raw materials may be used alone or in combination of two or more components.

  The ozone permeability of the protective layer can be adjusted by the gas component forming the film, the film forming speed, and the like.

  Next, the image forming apparatus will be described.

<Image formation>
The photoreceptor of the present invention can be used not only in an image forming apparatus using electrophotography, but also widely used in electrophotographic applications such as laser beam printers, CRT printers, and laser plate making.

  Hereinafter, an image forming apparatus in which the photoreceptor of the present invention is preferably used will be described.

  FIG. 7 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus in which the photoconductor of the present invention can be used.

  The image forming apparatus 1 shown in FIG. 7 is capable of digital image formation, and is roughly composed of an image reading unit A, an image processing unit B, an image forming unit C, and a transfer paper transport unit D.

  In the upper part of the image reading unit A, automatic document feeding means for automatically conveying the document is provided, and the document placed on the document placing table 11 is separated and conveyed one by one by the document conveying roller 12, and the reading position 13a. Then, the image is read. The document whose image has been read is discharged onto the document discharge tray 14 by the document conveying roller 12.

  In addition to the automatic image reading described above, the image forming apparatus 1 shown in FIG. 7 can also read an original on the platen glass 13 one by one. When reading on the platen glass 13, the original image is read by the illumination mirror constituting the scanning optical system, the first mirror unit 15 including the first mirror, and the second mirror having a structure in which two mirrors are arranged in a V shape. Each unit 16 is moved. In the image forming apparatus of FIG. 7, the original image is read with the moving speed of the first mirror unit 15 set to v and the moving speed of the second mirror unit set to v / 2.

  The image read by the image reading unit A according to the above-described procedure is converted into a digital image signal by the next image processing unit B. In the image processing unit B, first, the image read by the image reading unit A is imaged on the light receiving surface of the image sensor CCD as a line sensor through the projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (luminance signal), and further converted into an A (analog) / D (digital) signal. The image signal converted into the digital signal is subjected to processing such as density conversion and filter processing, and the formed image information is temporarily stored in the memory as an image signal.

  The image forming unit C performs toner image formation using the digital signal formed by the image processing unit B, and has a unit structure in which components used for image formation are assembled as shown in FIG. . The image forming unit constituting the image forming unit C includes a drum-shaped photoconductor 21, a charging unit (charging process) 22 for charging the photoconductor 21 on the outer periphery of the photoconductor 21, and supplying toner to the photoconductor 21. Developing means (developing step) 23 and the like are arranged. Further, on the outer periphery of the photoconductor 21, a transfer conveyance belt device 45 that is a transfer unit (transfer process) for transferring a toner image formed on the photoconductor 21 onto a sheet P or the like, and residual toner on the photoconductor 21 are removed. A cleaning device (cleaning step) 26 and a precharge lamp 27 which is a light discharging means (light slowing step) for discharging the surface of the photoreceptor 21 in preparation for the next image formation are arranged. These members from the charging unit 22 arranged on the outer periphery of the photoconductor 21 to the light neutralizing unit 27 are arranged in the order of operations performed at the time of image formation.

  Further, on the downstream side of the developing means 23, a reflection density detecting means 222 for measuring the reflection density of the patch image developed on the photosensitive member 21 is provided. As the photoconductor 21, a pyranthrone compound having peaks at Bragg angles of 12.3 °, 20.5 °, 25.3 °, and 28.3 °, which is the electrophotographic photoconductor according to the present invention, is used as a charge generating material. The photoconductor 21 is used and rotated in the illustrated direction, that is, in the clockwise direction during image formation.

  Next, a method for exposing the photosensitive member 21 will be described. The photosensitive member 21 is rotated by a driving unit (not shown), and the photosensitive member 21 is uniformly charged by the charging unit 22 during the rotation. The exposure optical system indicated by an image exposure unit (image exposure step) 30 stores the memory of the image processing unit B. The image is exposed on the basis of the image signal called from.

  An image exposure unit 30 corresponding to a writing unit that writes image information on the photosensitive member 21 uses a laser diode (not shown) as a light emission source, and an exposure sent by a polygon mirror 31, an fθ lens 34, a cylindrical lens 35, and a reflection mirror 32. Main scanning is performed with light. Image exposure is performed by irradiating the photosensitive member 21 with exposure light sent in this way at a position Ao in the drawing, and an electrostatic latent image is formed by rotation (sub-scanning) of the photosensitive member 21.

  In the present invention, when forming an electrostatic latent image on the photosensitive member 21, a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm is used as an exposure light source, and the dot diameter of exposure light from these exposure light sources is set to 10 to 10. It is preferable to perform exposure by setting to 50 μm. By exposure using so-called fine dot light in which the oscillation wavelength of the exposure light source and the exposure dot diameter are within the above ranges, it becomes possible to form a high-definition dot image compatible with digital image formation on the photosensitive member 21. . In other words, when the oscillation wavelength and the exposure dot diameter are within the above ranges, it is possible to form a high-resolution image on the photosensitive member 21 of, for example, 1200 dpi (dots per inch (2.54 cm per inch)) or more. become.

The exposure dot diameter refers to the length of the exposure beam along the main scanning direction in a region where the intensity of the exposure beam is 1 / e ² or more of the peak intensity. Examples of the light source of the exposure beam include a scanning optical system using a semiconductor laser and a solid state scanner using a light emitting diode (LED). Further, the intensity of the exposure beam can be expressed by a Gaussian distribution, a Lorentz distribution, or the like. However, in the present invention, it is not necessary to specify the light intensity distribution, and the exposure beam intensity consists of a region that is 1 / e ² or more of the peak intensity. What is necessary is just to be able to form a dot diameter of 10 to 50 μm in diameter.

  In addition, when a surface emitting laser array having three or more laser beam emission points in the vertical and horizontal directions is used as the exposure beam, the electrostatic latent image can be quickly written on the electrophotographic photosensitive member, so that high-speed printing can be performed. Preferred above. Then, by performing exposure with the surface emitting laser array on the electrophotographic photosensitive member according to the present invention capable of forming a stable latent image even if image formation is repeated, a printed matter having stable image quality can be quickly produced. To be able to

  The electrostatic latent image formed on the photoconductor 21 is developed by receiving toner supply from the developing unit 23, and a visible toner image is formed on the surface of the photoconductor 21. In order to realize high-definition image formation corresponding to digital, it is preferable to use polymerized toner as the developer supplied by the developing unit 23. That is, the polymerized toner can be produced while controlling the shape and particle size distribution in the production process. Accordingly, an electrophotography containing a small diameter toner having a uniform shape and size by a polymerization method and a pyranthrone compound having peaks at Bragg angles of 12.3 °, 20.5 °, 25.3 °, and 28.3 °. By using in combination with the photoreceptor, high-definition image formation with excellent sharpness is realized.

  Next, the transfer paper transport unit D transports the paper P, onto which the toner image formed on the outer periphery of the photoreceptor 21 in the image forming unit C has been transferred by the transfer unit 45, toward the next fixing unit 50. The transfer paper transport section D is provided with paper feed units 41 (A), 41 (B), and 41 (C), which are transfer paper storage means for storing transfer paper P of different sizes below the image forming unit. In addition, a manual paper feeding unit 42 that performs manual paper feeding is provided on the side of the paper feeding unit. The transfer paper P is selected from any of these transfer paper storage means, and is fed along the transport path 40 by the guide roller 43.

  The transfer paper transport unit D is provided with a paper feed registration roller 44 configured by a pair for correcting the inclination and bias of the transfer paper P to be fed. The transfer paper P is temporarily stopped by the paper feed registration roller 44. After that, it is fed again. The re-fed transfer paper P is guided to the transport path 40, the pre-transfer roller 43a, the paper feed path 46, and the entry guide plate 47.

  The toner image formed on the photoreceptor 21 is transferred onto the transfer paper P by the transfer pole 24 and the separation pole 25 at the transfer position Bo. At this time, the transfer paper P is transferred to the transfer paper belt 454 of the transfer and transport belt device 45 while being transferred to the transfer paper belt 454. The transfer paper P on which the toner image is transferred is transferred from the surface of the photosensitive member 21. The paper is separated and conveyed toward the fixing unit 50 by the transfer conveyance belt device 45.

  The fixing unit 50 includes a fixing roller 51 and a pressure roller 52. When the transfer paper P passes between the fixing roller 51 and the pressure roller 52, the toner image on the transfer paper P is heated and pressed. To fix. When the toner image is fixed on the transfer paper P in this way, the transfer paper P is discharged onto the paper discharge tray 64.

  With the above procedure, the image forming apparatus of FIG. 7 can transfer the toner image to one side of the transfer paper P and create a printed matter on which the image is formed on one side. It is also possible to create a printed matter that has been transferred.

  When toner images are formed on both sides of the transfer paper P, the paper discharge switching member 170 of the transfer paper transport unit D is actuated to open the transfer paper guide unit 177, and the transfer paper P having a toner image formed on one side is broken. It is conveyed in the direction of the arrow. The transfer paper P is transported downward by the transport mechanism 178, is switched back by the transfer paper reversing unit 179, and is transported into the duplex printing paper supply unit 130 with the side that was the rear end of the transfer paper P being the leading edge. Is done.

  The transfer paper P is moved in the paper feed direction by a conveyance guide 131 provided in the double-sided copy paper feed unit 130, and the transfer paper P is fed again by the paper feed roller 132, and the transfer paper P enters the conveyance path 40. Guided. Then, according to the above-described procedure, the transfer paper P is transported in the direction of the photoconductor 21, the toner image is transferred to the back surface of the transfer paper P, fixed by the fixing unit 50, and then discharged to the paper discharge tray 64. . By such a procedure, it is possible to create a printed matter in which toner images are formed on both sides of the transfer paper P.

  Further, in the image forming apparatus shown in FIG. 7, a so-called process cartridge having a unit structure in which the photosensitive member 21, the developing means 21, the cleaning device 26 and the like are integrally coupled is formed, and this is attached to and detached from the apparatus main body. It is also possible to adopt a method of freely configuring. Further, in addition to a unit which forms all the components as in a process cartridge, at least one of a charger, an image exposure device, a developing means 23, a transfer or separation device, and a cleaning device is integrated with the photosensitive member 21. It is also possible to form a supported cartridge and to make a unit that can be detachably set to the apparatus main body.

  As described above, the toner image formed by the image forming apparatus using the photoconductor of the present invention is finally transferred onto the transfer paper P, and fixed on the transfer paper P through a fixing process. The transfer paper P used in the image forming apparatus is a support that holds a toner image, and is usually called an image support, a recording material, or a transfer material. Specifically, commercially available copy paper called plain paper or high-quality paper, printing paper that has been subjected to coating processing such as art paper or coated paper, commercially available Japanese paper or postcard paper, OHP plastic film, cloth, etc. Although what is mentioned is mentioned, what can be used for this invention is not limited to these.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this.

<< Production of photoconductor >>
A photoreceptor was prepared as follows.

(Preparation of substrate)
The cylindrical aluminum was cut (JISB-0601 standard 10-point surface roughness Rz: 0.81 μm) and then washed to prepare a substrate. This is referred to as “base 1”.

<Preparation of Photoreceptor 1>
(Formation of intermediate layer)
1 part by weight of binder resin (N-1) is added to 20 parts by weight of ethanol / n-propyl alcohol / tetrahydrofuran (45:20:35 volume ratio), dissolved with stirring, and then surfaced with 5% by weight of methyl hydrogen polysiloxane. 4.2 parts by mass of the treated rutile-type titanium oxide particles were mixed, and the mixed solution was dispersed using a bead mill. At this time, an average particle size of 0.1 to 0.5 mm was used and dispersed at a filling rate of 80%, a peripheral speed setting of 4 m / sec, and a mill residence time of 3 hours to prepare an intermediate layer coating solution. After the same solution was filtered through a 5 μm filter, the intermediate layer coating solution was applied to the outer periphery of the “substrate 1” prepared above by a dip coating method to form “intermediate layer 1” having a dry film thickness of 2 μm.

(Formation of charge generation layer)
The following components were mixed and dispersed using a sand mill disperser to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form “charge generation layer 1” having a dry film thickness of 0.3 μm.

Y-titanyl phthalocyanine (Titanyl phthalosine pigment having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum by Cu-Kα characteristic X-ray) 20 parts by mass Polyvinyl butyral (BX -1, manufactured by Sekisui Chemical Co., Ltd.) 10 parts by mass Methyl ethyl ketone 700 parts by mass Cyclohexanone 300 parts by mass (formation of charge transport layer)
The following components were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method and dried at 120 ° C. for 70 minutes to form a “charge transport layer” having a dry film thickness of 20 μm.

Charge transport material (the following structure) 50 parts by weight Polycarbonate resin “Iupilon-Z300” (Mitsubishi Gas Chemical Co., Ltd.) 100 parts by weight Antioxidant 2,6-di-t-butyl-4-methylphenol 8 parts by weight Tetrahydrofuran / Toluene (Volume ratio 8/2) 750 parts by mass

(Formation of protective layer)
Next, a protective layer was formed on the “charge transport layer 1” using the second manufacturing apparatus (plasma discharge treatment apparatus) shown in FIG.

  Tetraethoxysilane (TEOS) was used as a material for forming the protective layer. As the dielectric covering each electrode of the plasma discharge processing apparatus at this time, both electrodes facing each other were coated with 1 mm thick alumina by ceramic spraying. The electrode gap after coating was set to 1 mm. In addition, the metal base material coated with a dielectric is a stainless steel jacket specification having a cooling function by cooling water. During discharge, the electrode temperature is controlled by cooling water, and the “protective layer 1” is formed. Photoconductor 1 ”was prepared.

  Table 1 shows the conditions for forming the protective layer. Each source gas was heated to generate steam, mixed and diluted with a discharge gas and a reaction gas that had been preheated so that the source material did not aggregate in advance, and then supplied to the discharge space.

(Protection layer deposition conditions)
Discharge gas: N ₂ gas reaction gas: 0 19 vol% with respect to ₂ gas all gases
Source gas: 1.4% by volume of tetraethoxysilane (TEOS) based on total gas
Low frequency side power (high frequency power (50 kHz) manufactured by Shinko Electric): 10 W / cm ²
High frequency side power supply (Pearl Industries high frequency power supply (13.56 MHz)): 5 W / cm ²
<Preparation of Photoreceptor 2>
“Photoreceptor 2” was produced in the same manner as in the production of photoconductor 1 except that the “protective layer 2” was formed by changing the formation conditions of the protective layer 1 as shown in Table 1.

<Preparation of Photoreceptor 3>
“Photoreceptor 3” was produced in the same manner as in the production of photoconductor 1, except that the “protective layer 3” was formed by changing the formation conditions of the protective layer 1 as shown in Table 1.

<Preparation of Photoreceptor 4>
“Photoreceptor 4” was produced in the same manner as in the production of photoconductor 1 except that the “protective layer 4” was formed by changing the formation conditions of the protective layer 1 as shown in Table 1.

<Preparation of Photoreceptor 5>
“Photoreceptor 5” was produced in the same manner as in the production of photoconductor 1 except that the “protective layer 5” was formed by changing the formation conditions of the protective layer 1 as shown in Table 1.

<Preparation of Photoreceptor 6>
“Photoreceptor 6” was produced in the same manner as in the production of photoconductor 1 except that the “protective layer 6” was formed by changing the formation conditions of the protective layer 1 as shown in Table 1.

<Preparation of photoconductor 7>
“Photoreceptor 7” was produced in the same manner as in the production of photoconductor 1 except that the “protective layer 7” was formed by changing the formation conditions of the protective layer 1 as shown in Table 1.

<Preparation of photoconductor 8>
In the production of the photoconductor 1, the photoconductor 8 without the protective layer 1 on the charge transport layer 1 was designated as “photoconductor 8” (no protective layer).

  Table 1 shows the conditions for forming the protective layers of the photoreceptors 1 to 7.

<Evaluation>
<Live-action evaluation>
“Bizhub PRO1050e” (manufactured by Konica Minolta Business Technologies, Inc.) was prepared as an image forming apparatus for actual image evaluation, and the photoreceptors prepared above were sequentially loaded, and the following evaluation items were evaluated. In addition, the evaluation results are ◎ and ○.

(Transfer memory)
In a high-temperature and high-humidity (30 ° C., 85% RH) environment where transfer memory is likely to occur, 750,000 prints of character images with a printing rate of 5% were printed. Thereafter, the developer is replaced with a new one, and 10 images of solid black and solid white mixed in the same environment are printed continuously, and then a uniform halftone image is printed. The degree of memory generation in which solid black and solid white histories appear was visually evaluated.

Evaluation criteria A: No occurrence of memory ○: A level where memory generation is recognized but no problem for practical use ×: A level where memory generation is recognized and causes a practical problem

(Image defects due to scratches)
In a low-temperature and low-humidity (10 ° C., 20% RH) environment in which scratches are likely to occur on the photoreceptor, 750,000 images with a printing rate of 5% were printed. Thereafter, the developer and the cleaning blade were replaced with new ones, a halftone image having an image density of 0.4 was printed, and image defects due to scratches on the photoreceptor were visually evaluated.

Evaluation Criteria A: Image defects due to photoconductor scratches are not recognized at all ○: Image defects due to photoconductor scratches are slightly present, but there is no practical problem ×: Image defects due to photoconductor scratches are many and practical The level at issue.

(Crack of protective layer)
In a low-temperature and low-humidity (10 ° C., 20% RH) environment, 750,000 images with a printing rate of 5% were printed. Thereafter, the developer and the cleaning blade were replaced with new ones, a halftone image having an image density of 0.4 was printed, and image defects due to cracks in the protective layer were visually evaluated.

Evaluation criteria ◎: Image defects due to cracks in the protective layer are not recognized at all ○: Image defects due to cracks in the protective layer are slightly present, but there is no practical problem ×: Many image defects due to cracks in the protective layer are practical The level at issue.

  Table 2 shows the results of live-action evaluation.

  From Table 2, it can be seen that the photoreceptors “1 to 5” of Examples 1 to 5 are excellent in evaluation of transfer memory, generation of scratches, and cracks in the protective layer after printing 750,000 sheets.

  On the other hand, it can be seen that the photoreceptors “6 to 8” of Comparative Examples 1 to 3 are not excellent in all the evaluation items and the object of the present invention is not achieved.

It is a schematic diagram which shows an example of the measuring apparatus by a nano indentation method. The schematic diagram of the state which the indenter and the sample are contacting is shown. FIG. 3 is a schematic diagram illustrating an example of a layer configuration of the photoreceptor of the present invention. It is explanatory drawing of the 1st manufacturing apparatus which manufactures a protective layer. It is explanatory drawing of the 2nd manufacturing apparatus which manufactures a protective layer. It is explanatory drawing of the 3rd manufacturing apparatus which manufactures a protective layer. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus that can use a photoconductor of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 11 Base | substrate 12 Intermediate | middle layer 13 Photosensitive layer 14 Charge generation layer 15 Charge transport layer 16 Protective layer

Claims (2)

In an electrophotographic photoreceptor comprising at least a substrate, an organic photosensitive layer and a protective layer,
The hardness measured by the nanoindentation method of the protective layer is 2-7 GPa,
An electrophotographic photoreceptor having an ozone transmittance of 10% or less. The electrophotographic photosensitive member according to claim 1, wherein the protective layer is formed by an atmospheric pressure plasma CVD method.

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