JP2006320791A - Coating method and manufacturing method of electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating method in which no pulse derived from a pump occurs in a coating liquid inside a coating tank, and a uniform coat layer can be obtained stably also in a continuous coating production by a stabilization in a current speed of the coating liquid in the coating tank. <P>SOLUTION: In the coating method in which a coating film is formed on a coating workpiece by immersing the coating workpiece in the coating liquid and pulling up it, a coating device is used. The coating device has the coating tank immersing the coating workpiece, a recovery tank receiving the coating liquid overflowing the upper end edge of a sidewall of the coating tank, and a reservoir receiving the coating liquid sent from the recovery tank through piping having a liquid sending means. The coating liquid in the reservoir overflows the upper end edge of a reservoir sidewall full-time while the coating workpiece is immersed and pulled up, and a flooded surface of the coating liquid in the reservoir holds a higher position than a flooded surface of the coating liquid in the coating tank, by which an inflow of the coating liquid from a lower position compared to the coating liquid flooded surface of the reservoir to the coating tank circulates the coating liquid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dip coating method, and more particularly to continuous dip coating in the production of an electrophotographic photoreceptor.

  In the production of an electrophotographic photosensitive member, a roll coater method, a spray method, an electrostatic coating method, a dip coating method, etc. as a method for forming a coating layer such as a photosensitive layer, an undercoat layer, and a surface protective layer on a conductive support. Is mentioned. Among these, the dip coating method is widely practiced because it is an advantageous method for producing a three-dimensional photoreceptor such as a cylindrical body or a seamless belt. This method uses a coating tank containing a coating liquid and a device for holding and lifting the coated body, immersing the coated body in the coating tank, and then pulling up the coated body at an appropriate speed. A coat layer is formed on the surface of the film.

  In this dip coating method, a desired film thickness can be obtained by appropriately setting coating conditions such as the viscosity, solid content, and pulling speed of the coating solution according to the object to be coated. However, in the dip coating method, the surface of the coating liquid is lowered by simply immersing the object to be coated in the coating tank and pulling it up, due to the excluded volume of the object to be coated. This not only reduces the dimensional accuracy of the upper end of the coating part, but also the coating liquid surface is in contact with air, so the coating liquid adheres as a film inside the upper part of the coating tank and eventually peels off and enters the coating liquid. By re-mixing, the coating solution is contaminated. Further, the concentration change due to the volatilization of the solvent is significant on the liquid level in the coating tank, and a concentration gradient occurs in the vertical direction of the coating tank, resulting in uneven application of the photoreceptor. In the dip coating method using the coating solution that has been allowed to stand in this way, the above-mentioned disadvantages occur, and this disadvantage appears more prominently during mass production.

  In view of this, a method has been devised and used in which a coating solution is continuously circulated between a collection tank provided separately from a coating tank (see Patent Document 1). As shown in FIG. 1, this method uses a liquid feeding means 103 to feed the coating liquid from the recovery tank 102 to the lower part of the coating tank 101, and overflows the coating liquid exceeding the capacity of the coating tank to the recovery tank. It is a mechanism to circulate. Thereby, the height of the liquid level in the coating tank is kept constant, and the concentration of the coating liquid in the coating tank becomes uniform. As the liquid feeding means, in order to maintain a stable flow rate of the coating liquid without being affected by the pressure resistance by the filter 104, a pump having a high liquid feeding pressure such as a diaphragm pump is usually used.

  However, such a liquid feeding means has a drawback of causing pulsation in the flow of the coating liquid, and as a result, the flow rate of the coating liquid in the coating tank becomes unstable. Since the film thickness of the coating layer in the dip coating is determined by the relative pulling speed of the coated body with respect to the coating liquid, the disturbance of the coating liquid flow rate in the coating tank is caused by unevenness in the coating layer formed on the coated body surface. Causes defects. Therefore, the method shown in FIG. 1 has a problem that it is difficult to obtain a uniform photosensitive layer.

  Further, as a method for improving this defect, as shown in FIG. 2, a storage tank 205 as a third tank is provided at a position higher than the coating tank 201 so that the pulsation by the liquid feeding means is not propagated to the coating tank. When the liquid is sent into the storage tank, a method has been proposed in which the liquid is once released under atmospheric pressure to release the pressurized state (see Patent Document 2). In this method, the liquid supply from the storage tank to the application tank is not performed using a power source such as a pump, and the liquid supply method uses only the gravity of the application liquid based on the principle of the siphon. Prevents fluid pulsation. This method has the advantage that pulsation by the pump does not reach the coating tank, but has the following disadvantages. First, it is difficult to keep the flow rate of the coating solution in the coating tank constant. That is, the flow rate of the coating liquid in the coating tank is affected by the difference in liquid level between the coating tank and the storage tank, and as long as the liquid level 206 of the coating tank always overflows and remains constant, the liquid in the storage tank Stabilizing the surface height 207 is a necessary condition for stabilizing the flow rate of the coating solution. However, in the case of the method illustrated in FIG. 2, when the coating object is immersed, the volume of coating liquid removed by the coating object is sent to the recovery tank at a time, so that the liquid in the storage tank is immediately after the coating object is pulled up. The surface will be lower than before immersion. In addition, consumption and replenishment of the coating liquid by continuous coating, and also increase / decrease of the total amount of coating liquid by replenishment of the dilution solvent accompanying adjustment of the viscosity of the coating liquid are factors that make the liquid level of the storage tank unstable, Accordingly, it is substantially difficult to keep the liquid level height of the storage tank constant and maintain the coating liquid flow rate in the coating tank constant during continuous application. Therefore, in continuous coating production, the value of the obtained film thickness tends to vary.

  The second disadvantage of the method of FIG. 2 is that the coating liquid is released from the pressurized state to the atmospheric pressure before entering the storage tank. It tends to occur. The bubbles may be sent to the coating tank and adhere to the object to be coated, which causes a coating defect.

Further, unlike FIG. 2, an apparatus has been proposed in which the storage tank is positioned higher than the application tank, unlike FIG. 2, but is not opened to atmospheric pressure when the coating liquid is sent to the storage tank (Patent Document). 3). Also in this method, it is difficult to keep the liquid level of the storage tank constant as in the method of FIG. 2, and it is not sufficient from the viewpoint of the flow rate stability of the coating liquid in the coating tank.
JP 59-90667 A Japanese Unexamined Patent Publication No. 09-122551 Japanese Patent Laid-Open No. 02-140751

  An object of the present invention is to eliminate the pulsation derived from the pump in the coating liquid in the coating tank, which has been a problem in the coating liquid circulation method in dip coating, and to stabilize the flow rate of the coating liquid in the coating tank. Another object of the present invention is to provide a coating method capable of stably obtaining a uniform coat layer even in continuous coating production, and a method for producing an electrophotographic photoreceptor using the coating method.

The present invention provides a coating method in which a coating film is formed on a coated body by immersing the coated body in a coating solution and pulling it up.
A coating tank for immersing the object to be coated, a recovery tank for receiving a coating liquid overflowing over the upper edge of the side wall of the coating tank, and a coating liquid sent from the recovery tank through a pipe having a liquid feeding means Using a coating device having a storage tank,
The coating liquid in the storage tank always overflows beyond the upper edge of the side wall of the storage tank while the substrate is immersed and pulled up, and the coating liquid overflow surface of the storage tank overflows the coating liquid in the coating tank. The coating method is characterized in that the coating liquid is circulated by holding the position higher than the surface and allowing the coating liquid to flow into the coating tank from a position lower than the coating liquid overflow surface of the storage tank.

  The present invention also provides a method for producing an electrophotographic photosensitive member using the coating method.

  According to the present invention, there is no pulsation derived from the pump in the coating liquid in the coating tank, which is a conventional problem in the coating liquid circulation method in the dip coating, and the flow rate of the coating liquid in the coating tank is stabilized. Further, it is possible to provide a coating method in which a uniform coat layer can be stably obtained even in continuous coating production, and a method for producing an electrophotographic photosensitive member using the coating method.

  A dip coating apparatus used in the coating method according to the present invention is shown in FIG. This will be described with reference to FIG. Reference numeral 300 denotes an object to be coated, and the upper part thereof is connected by a lifting device (not shown). Reference numeral 301 denotes an application tank for dip-coating an object to be coated. The coating liquid that always overflows the coating tank moves to the recovery tank 302 via the pipe. The coating liquid in the recovery tank is sent to the storage tank 305 by the liquid feeding means 303. Examples of the liquid feeding means include a diaphragm pump and a magnet pump. In the storage tank, like the coating tank, the coating liquid always overflows. Further, both tanks are arranged so that the coating liquid overflow surface 307 of the storage tank is positioned higher than the coating liquid overflow surface 306 of the coating tank. The coating liquid in the storage tank is sent to the coating tank by gravity from an outlet 309 provided at a position lower than the coating liquid overflow surface 307. Since the two overflow surfaces 306 and 307 that determine the flow rate of the coating liquid always overflow, they always maintain a constant height difference, and thus the flow rate of the coating liquid in the coating tank is a constant value. Can be maintained. Further, by causing the coating liquid to overflow in the storage tank, the pulsation of the coating liquid by the liquid feeding means is absorbed on the overflow side of the storage tank and is not transmitted to the coating tank. Furthermore, by providing the coating liquid inlet 308 in the storage tank at a position lower than the coating liquid overflow surface 307, it is possible to prevent air entrainment and shaking of the coating liquid overflow surface 307 when the coating liquid flows in. . In addition, the coating liquid overflowing from the storage tank is not sent directly to the coating tank, and the piping is configured so that it again passes through the filter 304 by the liquid feeding means. Therefore, if foreign matter such as dust or dust is mixed in the coating liquid in the storage tank, these are not sent directly to the coating tank, but are discharged by overflow in the storage tank. Inflow.

  Next, another embodiment of the dip coating apparatus used in the coating method according to the present invention is shown in FIG. A shielding object 410 such as a partition plate is provided between a straight line connecting the coating liquid inlet 408 and the outlet 409 in the storage tank 405 to prevent a short path of the coating liquid from the inlet to the outlet. In addition, by making the height position of the storage tank variable by the height adjusting means 411 so that the flow rate of the coating liquid in the coating tank 401 can be adjusted according to the type and properties of the coating liquid, or the desired film thickness, The mechanism is such that the height difference between the coating liquid overflow surfaces 406 and 407 in each of the coating tank and the storage tank can be adjusted. Here, the difference in the height of each overflow surface between the coating tank and the storage tank is preferably 10 to 1000 mm, more preferably 10 to 400 mm. As another means for adjusting the flow rate of the coating solution in the coating tank, a flow rate adjusting valve 412 may be disposed between the storage tank and the coating tank. The flow rate of the coating liquid in the coating tank is preferably 50 to 600 mm / min, more preferably 100 to 500 mm / min. Here, the flow velocity is a value calculated from measured values of the distance and time that the coating liquid rises in the coating tank after the liquid level of the coating liquid in the coating tank is once lowered to the lower part of the coating tank. If the flow rate in the coating tank is too small, a concentration gradient tends to occur in the coating solution, and if it is excessively large, the coating tends to be disturbed. In the coating method according to the present invention, since the liquid feeding from the storage tank to the coating tank is based only on gravity, the liquid feeding pressure can be controlled only within a weak range. In the place 415 where the pipe between the two tanks is arranged horizontally, air bubbles may stay in the pipe, and air bleed circulation for forcibly discharging the air bubbles to the coating tank side during maintenance is performed. In doing so, the pressure may be insufficient with only liquid feeding by gravity. Therefore, in order to enable forced bubble discharge maintenance using the pressure of the liquid feeding means, a valve 416 that leads directly from the secondary side of the liquid feeding means 403 to the coating tank side without passing through the storage tank is provided. A branch pipe 413 and valves 417 and 418 are arranged so that air can be circulated.

  Further, a mesh is used for the liquid receiving portion 414 of the recovery tank, and it is configured to trap foreign matters such as dust and bubbles.

  The coating method according to the present invention works particularly effectively for a coating solution having a relatively low viscosity of 100 mPas or less, particularly 10 mPas or less.

  In the present invention, the volume of the storage tank is 10 to 30 liters, the thickness of the pipe is in the range of 20 to 60 mm, and the length of one pipe does not exceed 3000 mm.

  Next, a method for producing an electrophotographic photoreceptor using the coating method according to the present invention will be described.

  The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a so-called laminated photosensitive layer having a charge generation layer and a charge transport layer on a cylindrical support. The laminated type photosensitive layer includes a normal layer type photosensitive layer laminated in the order of the charge generation layer and the charge transport layer from the support side, and a reverse layer type photosensitive layer laminated in the order of the charge transport layer and the charge generation layer from the support side. From the viewpoint of electrophotographic characteristics, a normal type photosensitive layer is preferred.

  As the cylindrical support (hereinafter also simply referred to as “support”), it is only necessary to have conductivity (conductive support). For example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, A support made of metal (made of alloy) such as molybdenum, chromium, titanium, nickel, indium, gold, or platinum can be used. In addition, the metal support having a layer formed by vacuum deposition of these metals (alloys) or a support made of plastic (polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyethylene terephthalate resin, acrylic resin, etc.) is used. You can also. In addition, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, and silver particles are impregnated into plastic or paper together with an appropriate binder resin, or a plastic support having a conductive binder resin, etc. Can also be used.

  The surface of the support may be subjected to cutting treatment, roughening treatment, alumite treatment, etc. for the purpose of preventing interference fringes due to scattering of laser light or the like.

  A conductive layer may be provided between the support and the charge generation layer or charge transport layer or an intermediate layer described later for the purpose of preventing interference fringes due to scattering of laser light or the like, or for covering scratches on the support. .

  The conductive layer can be formed by dispersing conductive particles such as carbon black, metal particles, and metal oxide particles in a binder resin.

  The thickness of the conductive layer is preferably 1 to 40 μm, and more preferably 2 to 20 μm.

  Further, an intermediate layer having a barrier function or an adhesive function may be provided between the support or the conductive layer and the charge generation layer or the charge transport layer. The intermediate layer is formed for the purpose of improving the adhesion of the photosensitive layer, improving the coating property, improving the charge injection property from the support, and protecting the photosensitive layer from electrical breakdown.

  The intermediate layer is acrylic resin, allyl resin, alkyd resin, ethyl cellulose resin, ethylene-acrylic acid copolymer, epoxy resin, casein resin, silicone resin, gelatin resin, phenol resin, butyral resin, polyacrylate resin, polyacetal resin, polyamideimide resin , Polyamide resin, polyallyl ether resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl alcohol resin, polybutadiene resin, polypropylene resin, urea resin, aluminum oxide, etc. It can be formed using the material. Further, the intermediate layer may contain metals, alloys, oxides thereof, salts, surfactants and the like.

  The thickness of the intermediate layer is preferably 0.05 to 7 μm, and more preferably 0.1 to 2 μm.

  The charge generation layer is formed by applying a charge generation layer coating solution obtained by dispersing a charge generation material together with a binder resin and a solvent, and drying and / or curing by heating and / or radiation irradiation. Can do. Examples of the dispersion method include a method using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, a liquid collision type high-speed disperser, and the like.

  Examples of the charge generating material include azo pigments such as monoazo, disazo, and trisazo, phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, indigo pigments such as indigo and thioindigo, and perylene acid anhydride and perylene imide. Perylene pigments, polycyclic quinone pigments such as anthraquinone and pyrenequinone, squarylium dyes, pyrylium salts and thiapyrylium salts, triphenylmethane dyes, inorganic substances such as selenium, selenium-tellurium, amorphous silicon, quinacridone pigments, And azurenium salt pigments, cyanine dyes, xanthene dyes, quinone imine dyes, styryl dyes, cadmium sulfide, and zinc oxide. These charge generation materials may be used alone or in combination of two or more.

  Examples of the binder resin used for the charge generation layer include acrylic resins, allyl resins, alkyd resins, epoxy resins, diallyl phthalate resins, silicone resins, styrene-butadiene copolymers, phenol resins, butyral resins, benzal resins, polyacrylate resins, Polyacetal resin, polyamideimide resin, polyamide resin, polyallyl ether resin, polyarylate resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl acetal resin, polybutadiene resin, polypropylene resin, Examples include methacrylic resin, urea resin, vinyl chloride-vinyl acetate copolymer, vinyl acetate resin and the like. In particular, a butyral resin is preferable. These can be used singly or in combination of two or more as a mixture or copolymer.

  The ratio of the binder resin in the charge generation layer is preferably 90% by mass or less, more preferably 50% by mass or less, with respect to the total mass of the charge generation layer.

  The solvent used in the coating solution for the charge generation layer is selected from the solubility and dispersion stability of the binder resin and charge generation material used, and the organic solvents include alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogens. Hydrocarbons and aromatic compounds.

  The thickness of the charge generation layer is preferably 0.001 to 6 μm, and more preferably 0.01 to 1 μm.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary.

  Next, the charge transport layer is formed by applying a charge transport layer, a binder resin coating solution obtained by dissolving a binder resin in a solvent, and drying and / or curing by heating and / or radiation irradiation. Can be formed. Examples of the charge transport material contained in the charge transport layer coating solution include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triarylmethane compounds. These charge transport materials may be used alone or in combination of two or more.

  The ratio of the charge transport material in the charge transport layer is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total weight of the charge transport layer. Therefore, the charge transport layer coating liquid preferably contains a charge transport material so that the ratio of the charge transport material after formation of the charge transport layer is in the above range.

  Examples of the binder resin to be included in the charge transport layer coating solution include acrylic resin, acrylonitrile resin, allyl resin, alkyd resin, epoxy resin, silicone resin, phenol resin, phenoxy resin, butyral resin, polyacrylamide resin, and polyacetal resin. , Polyamideimide resin, polyamide resin, polyallyl ether resin, polyarylate resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl butyral resin, polyphenylene oxide resin, polybutadiene resin, polypropylene Examples thereof include resins, methacrylic resins, urea resins, vinyl chloride resins, and vinyl acetate resins. In particular, polyarylate resin, polycarbonate resin and the like are preferable. These can be used singly or in combination of two or more as a mixture or copolymer.

  The ratio between the charge transport material and the binder resin is preferably in the range of 5: 1 to 1: 5 (mass ratio).

  Examples of the solvent used in the charge transport layer coating solution include monochlorobenzene, dioxane, toluene, xylene, N-methylpyrrolidone, dichloromethane, tetrahydrofuran, and methylal.

  In addition, an antioxidant, an ultraviolet absorber, a plasticizer, and the like can be added to the charge transport layer, that is, the charge transport layer coating solution, as necessary.

  A protective layer may be provided on the charge transport layer (in the case of a normal layer type photosensitive layer) or a charge generation layer (in the case of a reverse layer type photosensitive layer) for the purpose of protecting it. The protective layer can be formed by applying a protective layer coating solution obtained by dissolving the various binder resins described above in a solvent, and drying and / or curing by heating and / or radiation irradiation.

  Further, the surface layer of the electrophotographic photosensitive member of the present invention may contain a lubricant. Examples of the lubricant include polymers, monomers and oligomers containing silicon atoms and fluorine atoms. Specifically, N- (n-propyl) -N- (β-acryloxyethyl) -perfluorooctylsulfonic acid amide, N- (n-propyl)-(β-methacryloxyethyl) -perfluorooctylsulfone Acid amide, perfluorooctanesulfonic acid, perfluorocaprylic acid, Nn-propyl-n-perfluorooctanesulfonic acid amide-ethanol, 3- (2-perfluorohexyl) ethoxy-1,2-dihydroxypropane, N -N-propyl-N-2,3-dihydroxypropyl perfluorooctylsulfonamide and the like. Also, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene Examples also include particles of fluorine atom-containing resins such as copolymers and tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymers. These may be used alone or in combination of two or more. Moreover, it is preferable that the number average molecular weights of a lubricant are 3000-5 million, and it is especially preferable that it is 10000-3000000. When the lubricant is a particle, the average particle diameter is preferably 0.01 to 10 μm, and particularly preferably 0.05 to 2.0 μm.

The surface layer of the electrophotographic photosensitive member of the present invention may contain a resistance adjusting agent. Examples of the resistance adjuster include SnO ₂ , ITO, carbon black, silver particles, and the like. Moreover, you may use what performed the hydrophobization process to these. The resistance of the surface layer when a resistance adjusting agent is added is preferably 10 ⁹ to 10 ¹⁴ Ω · cm.

  When the protective layer is provided, the protective layer is a surface layer of the electrophotographic photosensitive member, and when the protective layer is not provided and the photosensitive layer is a normal type photosensitive layer, the charge transport layer is the electrophotographic photosensitive member. In the case where the protective layer is not provided and the reverse type photosensitive layer, the charge generation layer is the surface layer of the electrophotographic photosensitive member.

  FIG. 5 shows an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 5, reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is driven to rotate at a predetermined peripheral speed in the direction of the arrow about the shaft 2.

  The surface of the electrophotographic photosensitive member 1 that is rotationally driven is uniformly charged to a predetermined positive or negative potential by a charging unit (primary charging unit: charging roller or the like) 3, and then subjected to slit exposure, laser beam scanning exposure, or the like. Exposure light (image exposure light) 4 output from exposure means (not shown) is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the surface of the electrophotographic photosensitive member 1.

  The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in the developer of the developing means 5 to become a toner image. Next, the toner image formed and supported on the surface of the electrophotographic photoreceptor 1 is transferred from a transfer material supply means (not shown) to the electrophotographic photoreceptor 1 and the transfer means by a transfer bias from a transfer means (transfer roller or the like) 6. 6 (contact portion) is sequentially transferred onto a transfer material (paper or the like) P taken out and fed in synchronization with the rotation of the electrophotographic photosensitive member 1.

  The transfer material P that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member 1 and introduced into the fixing means 8 to receive the image fixing, and is printed out as an image formed product (print, copy). Is done.

  The surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is cleaned by a cleaning means (cleaning blade or the like) 7 to remove the developer (toner) remaining after transfer, and further from a pre-exposure means (not shown). After being subjected to charge removal processing by pre-exposure light (not shown), it is repeatedly used for image formation. As shown in FIG. 5, when the charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not necessarily required.

  Among the above-described components such as the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, the transfer unit 6, and the cleaning unit 7, a plurality of components are housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. In FIG. 5, the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5 and the cleaning unit 7 are integrally supported to form a cartridge, and the electrophotographic apparatus is used by using a guide unit 10 such as a rail of the electrophotographic apparatus main body. The process cartridge 9 is detachable from the main body.

  The coating method of the present invention can be used for dip coating in the formation of a conductive layer, an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer. It is particularly suitable for an intermediate layer, a charge generation layer, and a protective layer, which are often set to a low viscosity.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these. In the examples, “part” means “part by mass”.

Example 1
An aluminum cylinder having a diameter of 30 mm and a length of 254 mm was used as a support (cylindrical support).

  Next, 10 parts of tin oxide-coated titanium oxide, 10 parts of titanium oxide, 10 parts of phenol resin, 0.001 part of silicone oil, 15 parts of methanol and 15 parts of methyl cellosolve are dispersed for 3 hours in a sand mill device, and applied for a conductive layer. A liquid was prepared.

  This conductive layer coating solution was dip-coated on a support using the coating apparatus shown in FIG. 1, and dried and cured at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 15 μm.

  Next, 10 parts of polyamide resin (trade name: M-4000, manufactured by Toray Industries, Inc.) is dissolved in a mixed solvent of 100 parts of methanol / 90 parts of isopropanol, and an intermediate layer coating solution having a viscosity of 8 mPa · s. Was prepared.

  This intermediate layer coating solution is dip coated on the conductive layer using the coating apparatus according to the present invention shown in FIG. 4 and dried at 90 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.6 μm. did. At this time, the height difference between the overflow surface 406 of the coating tank and the overflow surface 407 of the storage tank was 70 mm, and the flow rate of the coating liquid in the coating tank was 380 mm / min.

  Next, 9 parts of HOGaPc crystals having strong peaks at 7.4 ° ± 0.2 ° and 28.1 ° of Bragg angle 2θ in X-ray diffraction of CuKα and polyvinyl butyral (trade name: ESREC BX-1, Sekisui Chemical) A solution obtained by dissolving 3 parts in 100 parts of tetrahydrofuran was dispersed for 3 hours with a sand mill using 1 mmφ glass beads. 200 parts of butyl acetate was added thereto for dilution and then recovered to obtain a charge generation layer coating solution having a viscosity of 1 mPa · s. This was applied by dip coating on the intermediate layer using the coating apparatus according to the present invention shown in FIG. 4 and dried at 80 ° C. for 15 minutes to form a charge generation layer having a thickness of 0.15 μm. At this time, the difference in height between the overflow surface 406 of the coating tank and the overflow surface 407 of the storage tank was 50 mm, and the flow rate of the coating liquid in the coating tank was 310 mm / min.

  Next, 10 parts of a styryl compound (charge transport material) having a structure represented by the following formula and 10 parts of a polycarbonate resin (trade name: Iupilon Z-400, manufactured by Mitsubishi Gas Chemical Co., Ltd.) are added to 120 parts of monochlorobenzene. It melt | dissolved and the coating liquid for charge transport layers was prepared. This charge transport layer coating solution was dip-coated on the charge generation layer using the coating apparatus shown in FIG. 1 and dried at 120 ° C. for 60 minutes to form a charge transport layer having a thickness of 30 μm. In this way, 100 electrophotographic photoreceptors whose surface layer was a charge transport layer were continuously prepared. When the film thickness of the intermediate layer and the charge generation layer was confirmed for every ten pieces, the intermediate layer maintained a stable state by maintaining a film thickness of 0.6 μm and the charge generation layer of 0.15 μm. In addition, there were no coating film defects such as turbulence, bubbles, and foreign matters in the coating film of the intermediate layer and the charge generation layer.

  Further, in the application of the intermediate layer coating solution, the flow rate of the coating solution in the coating tank when the drop between the coating solution overflow surfaces 406 and 407 is changed using the height position adjusting means 411 shown in FIG. As shown in FIG. As can be seen from FIG. 6, the flow rate can be freely controlled by adjusting the drop between the coating liquid overflow surfaces 406 and 407.

It is a figure for demonstrating the conventional dip coating method. It is a figure for demonstrating the conventional dip coating method. It is a figure for demonstrating the dip coating method of this invention. It is a figure for demonstrating the dip coating method of this invention. 1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention. FIG. 5 is a correlation diagram between the overflow surface drop in the coating apparatus of FIG. 4 and the flow velocity in the coating tank of the intermediate layer coating solution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photosensitive member 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 10 Guide means P Transfer material 100, 200, 300, 400 To-be-coated body 101, 201, 301, 401 Coating tank 102, 202, 302, 402 Recovery tank 103, 203, 303, 403 Liquid feeding means 104, 204, 304, 404 Filter 205, 305, 405 Storage tank 106, 206, 306, 406 Overflow surface (coating tank )
207, 307, 407 Overflow surface (storage tank)
308, 408 Coating liquid inlet (storage tank)
309, 409 Application liquid outlet (storage tank)
410 Shield 411 Height Position Adjusting Unit 412 Valve 413 Maintenance Branch Pipe 414 Liquid Receiving Portion (Recovery Tank)
415 Piping horizontal arrangement part 416, 417, 418 Valve

Claims (6)

In the coating method of forming a coating film on the coated body by immersing and lifting the coated body in a coating solution,
A coating tank for immersing the coated body, a recovery tank for receiving the coating liquid overflowing over the upper edge of the side wall of the coating tank, and a coating liquid sent from the recovery tank through a pipe having a liquid feeding means Using a coating device having a storage tank,
The coating liquid in the storage tank always overflows beyond the upper edge of the side wall of the storage tank while the substrate is immersed and pulled up, and the coating liquid overflow surface of the storage tank overflows the coating liquid in the coating tank. A coating method, wherein the coating liquid is circulated by holding the position higher than the surface and allowing the coating liquid to flow into the coating tank from a position lower than the coating liquid overflow surface of the storage tank.   The coating method according to claim 1, wherein the coating liquid sent from the recovery tank flows into the storage tank from a position lower than the coating liquid overflow surface of the storage tank.   The coating method according to claim 1, wherein a straight line connecting the pipe connection port on the collection tank side and the pipe connection port on the application tank side in the storage tank is shielded by a shielding object.   The coating method according to claim 1, wherein one or both of the storage tank and the coating tank have means for adjusting the height position of the one or both.   The coating method according to claim 1, wherein the coating liquid overflowing in the storage tank is not sent directly to the coating tank, but is returned to the recovery tank or the storage tank via a pipe. A method for producing an electrophotographic photosensitive member, wherein the coating method according to claim 1 is used.

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