JP4774765B2 - Coating device, coating method, endless belt manufacturing method, endless belt obtained by the method, and electrophotographic apparatus - Google Patents

Description

  The present invention relates to a coating apparatus, a coating method, an endless belt manufacturing method, and an endless belt obtained by the method. The endless belt can be preferably used for a photoreceptor belt or a transfer belt in an electrophotographic apparatus. The present invention also relates to an electrophotographic apparatus provided with this endless belt.

  In an electrophotographic apparatus, a belt made of a plastic film that is thin and deformable may be used as a photosensitive member or a transfer member. If there is a seam on the belt, the output image will be traced. Therefore, an endless belt without a seam is preferable.

  In order to produce such an endless belt, a film-forming resin solution was applied to the outer surface of the cylindrical core body by a spiral coating method described in Patent Document 1 or a float coating method described in Patent Document 2, thereby forming a resin film. After that, there is a method of removing the resin film from the core.

  However, in order to produce an endless belt having a large circumferential length, that is, a large diameter by this method, it is necessary to prepare a cylindrical core body having a size corresponding to the endless belt. In particular, a cylindrical core having a diameter of 300 mm or more becomes expensive, and the cost of an endless belt obtained from the cylindrical core increases.

  On the other hand, in an endless belt having a seam, image formation must be performed while avoiding the seam, but in an endless belt having a long circumference, that is, a large diameter, the ratio of the portion including the seam is relative to the entire area. Therefore, even with an endless belt having a seam, it is relatively easy to form an image.

  On the other hand, when the circumference of the endless belt having a seam is shorter than the length of the image, the endless belt seam is included in the image, which is not suitable for image forming applications.

As a method for producing an endless belt having a seam, a method in which a film is rolled and joined is common. As a joining method, in addition to joining with an adhesive, as described in Patent Document 3, There are also an ultrasonic welding method and a puzzle cut joining method as described in Patent Document 4. However, in these joining methods, the joining portions are overlapped and the adhesive swells, so there is a disadvantage that the thickness increases, and the increase in the thickness of the endless belt may cause uneven rotation speed. For this reason, it is not preferable in driving the belt.
Japanese Patent Laid-Open No. 10-69183 JP 2002-91027 A JP-A-7-223263 JP-A-8-66974

  On the other hand, there is also a method of producing an endless belt by application, for example, a method of producing a resin film by rotating and applying a film-forming resin solution from a slit to the outer surface of a cylindrical core body. In this case, a seam is formed before and after the application, but since the portion is smoothed by the surface tension of the solution, the increase in thickness is small. Although this method is relatively easy to apply, it is disadvantageous in that a cylindrical core of that diameter must be prepared.

  Therefore, a method that can be applied without preparing a cylindrical core has been desired.

  Accordingly, an object of the present invention is to provide a coating apparatus and a coating method for obtaining a large-diameter endless belt at low cost. Moreover, it is providing the endless belt manufacturing method using this, and the endless belt obtained by it. Another object is to provide an electrophotographic apparatus to which the obtained endless belt is applied.

The above problem is solved by the following means.
That is, the coating apparatus of the present invention is a coating apparatus for continuously applying and coating the coating solution from the slit to the belt substrate surface having a seam,
The start position of the application is at or near the joint of the belt base.

  In the coating apparatus of the present invention, an inexpensive and flexible belt base that is simply a rolled metal thin plate or a resin film is used as the substrate to be coated, instead of a rigid cylindrical body, and the coating solution is applied to the surface of the belt substrate. By coating, a coating film for obtaining a large-diameter endless belt can be easily formed. Moreover, by setting the coating start position at or near the joint of the belt base, a defective portion caused by transfer by the joint of the belt base and a streak defective portion generated at the joint of the coating film at the start and end of coating Are overlapped at the same position and, as a result, have only one defective portion, which is sufficiently practical. Further, the endless belt obtained by coating does not increase the thickness of the seam.

  In the coating apparatus of the present invention, the belt substrate preferably has a diameter of 300 mm or more. The coating apparatus of the present invention is suitable for forming a coating film for obtaining an endless belt having a large diameter of, for example, 300 mm or more.

On the other hand, the coating method of the present invention is a coating method in which a coating solution is continuously extruded from a slit and applied to the belt substrate surface having a seam,
The start position of the application is at or near the joint of the belt base.

  In the coating method of the present invention, a coating film for obtaining a large-diameter endless belt can be easily obtained in the same manner as the coating apparatus of the present invention. Moreover, the endless belt obtained from the coating film has only one defective portion, and is sufficiently practical depending on the application.

  Also in the coating method of the present invention, the belt substrate preferably has a diameter of 300 mm or more. The coating method of the present invention is suitable for forming a coating film for obtaining an endless belt having a large diameter of, for example, 300 mm or more.

In addition, the method for producing an endless belt of the present invention includes:
A step of applying a film-forming resin solution to a belt substrate having a seam by the application method of the present invention;
Heating the applied film-forming resin solution to form a resin film;
Removing the resin film from the belt substrate;
It is characterized by having.

  In the method for producing an endless belt of the present invention, a coating film for obtaining a large-diameter endless belt can be easily obtained by applying the coating method of the present invention when the film-forming resin solution is applied. Moreover, a practical endless belt having only one defective portion can be obtained.

  Moreover, the endless belt of the present invention is obtained by the method for producing an endless belt of the present invention.

  Further, in the endless belt of the present invention, the defective portion generated by the transfer by the joint of the belt base and the defective portion generated by the joint of the coating film at the start and end of the coating overlap at the same position. The endless belt may be an image forming apparatus belt, and a circumference thereof may be equal to or longer than a length of an output image by the image forming apparatus. Thereby, although it has one defective part, it does not become a problem in practical use as a belt for an image forming apparatus.

  The electrophotographic apparatus of the present invention is characterized by including the endless belt of the present invention.

  According to the present invention, it is possible to provide a coating apparatus and a coating method for obtaining a large-diameter endless belt at low cost. Moreover, the manufacturing method of an endless belt using this, and the endless belt obtained by it can be provided. Moreover, an electrophotographic apparatus provided with the obtained endless belt can be provided.

  Hereinafter, the manufacturing method of the endless belt of the present invention will be described in detail together with the coating apparatus and the coating method of the present invention.

  The process for producing an endless belt of the present invention includes a step of applying a film-forming resin solution to a belt substrate (application step), and a step of heating the applied film-forming resin solution to form a resin film (film formation step). And a step of removing the resin film from the belt substrate (removal step). Hereinafter, each step will be described.

(Coating process)
In the coating step, a belt base having a seam is prepared, and a film-forming resin solution is applied to the outer peripheral surface of the belt base. Specifically, a coating process is performed using the coating apparatus shown in FIG. Here, FIG. 1 is a schematic configuration diagram showing an example of the coating apparatus of the present invention. FIG. 2 is an enlarged view showing an example of a joint of the belt base. FIG. 2A shows a case where the belt base is made of a resin film, and FIG. 2B shows a case where the belt base is made of a thin metal plate. Is shown.

  A coating apparatus shown in FIG. 1 includes a belt substrate 10 having a joint 10A as a substrate to be coated, a support roll 12 for supporting and rotating the belt substrate 10, and an applicator 14 disposed around the belt substrate 10. And comprising.

  The belt base 10 is manufactured by rolling a thin metal plate such as nickel, stainless steel, copper, or the like, or a heat-resistant resin film such as polyimide resin, and bonding them by a method such as adhesion or welding. The thickness is preferably about 0.05 to 1 mm, although it depends on the material. With this method, even a large diameter of 300 mm or more can be easily manufactured.

  Here, when the belt base 10 is made of a resin film as shown in FIG. 2A, the belt base 10 has a convex seam 10A along the belt width direction by adhesion, and is made of a thin metal plate. In this case, as shown in FIG. 2B, the convex seam 10A is provided along the belt width direction by welding, and it is also effective to smooth the seam 10A. Moreover, in the case of a resin film, it may be joined by the puzzle cut method described in Patent Document 4, but a convex seam is also formed at the joined portion, so that smoothing is preferable. To smooth the seam, there is a method of polishing with a file or sandpaper.

  A release agent may be applied to the surface of the belt base 10 so that the obtained coating resin does not adhere. Further, the surface may be roughened by blasting or the like.

  The applicator 14 is a so-called slit coater having a slit 16. There is a liquid reservoir 18 inside, and a film-forming resin solution is injected into the liquid reservoir 18 from the outside by a pump or air pressure from a pipe (not shown) and pushed out from the slit 16. The gap of the slit 16 is adjusted according to the applied thickness. The width of the slit 16 (the length in the width direction of the belt base 10) is longer than the width of the desired endless belt.

  The support roll 12 is formed of a cylindrical body having substantially the same diameter as the belt diameter, and supports the belt base 10 by fitting the cylindrical body. And it is connected with the drive member (not shown) so that rotation is possible. Even if a cylindrical body having substantially the same diameter as the belt base 10 cannot be prepared, the belt base 10 can be stretched and supported by a plurality of support rolls 12, as shown in FIG.

  In the coating apparatus shown in FIG. 1, when the film base resin solution is extruded from the slit 16 of the applicator 14 while the belt base 10 is supported and rotated by the support roll 12, a coating film 20 is formed on the surface of the belt base 10, By causing the belt base 10 to make one turn, the coating film 20 is formed on the entire circumference of the belt base 10 surface.

  Here, usually, even if the film-forming resin solution is extruded from the applicator 14 (slit coater) and applied to the surface of the belt substrate 10 once, a mark remains on the joint at the start and end of application or smoothing is performed. Even if there is no apparent trace, a defect portion is generated in terms of characteristics, for example, mechanical properties and electrical characteristics. On the other hand, the surface shape of the joint 10A of the belt base 10 as the substrate to be coated is transferred to the coating film and becomes a defective portion. Even if the joint 10A is smoothed to prevent this, it cannot be completely smoothed. After all, it is slightly transferred and a defective part is generated.

  Therefore, the position at which the film forming resin solution begins to be pushed out from the slit 16 of the applicator 14 (that is, the application start position) is the seam 10A of the belt base 10 or the vicinity thereof. That is, by matching the joint at the start and end of application of the film-forming resin solution (the joint of the coating film 20) and the joint 10A of the belt base 10, the joints overlap each other and there is only one defective portion. It is. Note that the vicinity of the joint 10A of the belt base 10 indicates an area within a region displaced by about 50 mm in the circumferential direction from the joint 10A.

  Thus, the coating film 20 for obtaining a large-diameter endless belt can be easily obtained by using the belt base 10 having a seam and applying the coating solution to the surface of the belt base. In addition, the endless belt obtained from the coating film 20 has a defective portion generated by the transfer of the joint of the belt base, and at the start and end of coating by setting the coating start position to the joint 10A of the belt base 10 or the vicinity thereof. The streak-like defect portion generated at the joint of the coating film overlaps at the same position, resulting in only one defect portion, which is sufficiently practical.

  Next, the film forming resin will be described. Examples of the film-forming resin include polyimide (PI), polyamideimide (PAI), polyamide, polycarbonate, polyarylate, and polyester. The concentration, viscosity and the like of the film forming resin solution are appropriately selected. In the application, when the resin material is a thermoplastic resin, the solution is used, and when the resin material is a non-thermoplastic resin such as PI, the precursor solution is used.

  The PI precursor solution is obtained by reacting an acid dianhydride and a diamine component in an aprotic polar solvent such as N-methylpyrrolidone, N, N-dimethylacetamide, acetamide, N, N-dimethylformamide or the like. be able to. The kind of PI is not limited, but an aromatic polyimide obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine component is preferable from the viewpoint of film strength.

  Representative examples of the aromatic tetracarboxylic acid include, for example, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetra Carboxylic dianhydride, 2,3,4,4'-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic Examples thereof include acid dianhydrides, 2,2-bis (3,4-dicarboxyphenyl) ether dianhydrides, tetracarboxylic acid esters thereof, and mixtures of the above tetracarboxylic acids.

  On the other hand, as aromatic diamine components, paraphenylenediamine, metaphenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminophenylmethane, benzidine, 3,3′-dimethoxybenzidine, 4,4′-diamino Examples include diphenylpropane and 2,2-bis [4- (4-aminophenoxy) phenyl] propane.

  The PAI resin is an organic acid anhydride such as trimellitic acid anhydride, ethylene glycol bisanhydro trimellitate, propylene glycol bis anhydro trimellitate, pyromellitic acid anhydride, benzophenone tetracarboxylic acid anhydride, 3 , 3 ', 4,4'-biphenyltetracarboxylic anhydride and the like and an organic diamine, and is obtained by polycondensation reaction in an equimolar amount. Since the PAI resin has an amide group, it easily dissolves in the solvent even if the imidization reaction proceeds. Therefore, the PAI resin is preferably 100% imidized by raising the reaction temperature from room temperature. The solvent is preferably the aprotic polar solvent.

  Organic diamines include bis [4- {3- (4-aminophenoxy) benzoyl} phenyl] ether, 4 · 4'-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl]. Sulfone, 2,2'-bis [4- (3-aminophenoxy) phenyl] propane, 3,3'-diaminobenzophenone, P-phenylenediamine, 4,4'-diaminodiphenyl, 4,4'-diaminodiphenylmethane, It is selected from any one or more of 4,4′-diaminodiphenyl ether and the like.

Here, when the endless belt needs conductivity, a conductive substance is dispersed in the film-forming resin. Examples of the conductive material include carbon-based materials such as carbon black, carbon fiber, carbon nanotube, and graphite, metals or alloys such as copper, silver, and aluminum, tin oxide, indium oxide, antimony oxide, SnO ₂ —In ₂ O. ₃ Conductive metal oxides such as complex oxides.

  When the film forming resin solution is applied, the application speed (peripheral speed during rotation) to the belt base 10 is preferably about 0.2 to 2 m / min, more preferably 0.4 to 1.5 m / min. is there.

(Film formation process)
In the film forming step, after the coating film is formed by the coating process, the coating film is dried, and the resin film can be formed by heating or curing as necessary. By this drying, the solvent after coating the film forming resin solution is evaporated.

  At the time of drying, the evaporation of the aprotic polar solvent is slow, so that the coating film tends to sag downward at the time of drying. In that case, you may dry, rotating a belt base | substrate.

  The drying conditions are performed by appropriately setting the temperature and time depending on the type of resin and the type of solvent. In the case of PAI resin, it is preferable to remove the residual solvent by heating to 200 to 300 ° C. In the case of the PI precursor, if the solvent completely evaporates, the film may be easily cracked. Therefore, a certain amount of the solvent (for example, about 5 mass% to 40 mass% at the beginning) should be left. The time is appropriately set at a temperature of about 50 to 150 ° C.

  Moreover, it heats further depending on resin with reaction. For example, in the case of a PI resin, for imidization, it is heated to 250 to 450 ° C. (preferably 300 to 400 ° C.) after drying, whereby the PI precursor becomes a PI resin. A preferable film thickness of the endless belt is about 30 to 150 μm.

(Removal process)
In the removing step, the resin film is extracted from the belt base, and slit processing, punching drilling processing, tape winding processing, or the like is performed on the end portion as necessary. Thus, the endless belt 22 is obtained. As shown in FIG. 4, the obtained endless belt 22 has a streak formed along the belt width direction as a result of overlapping of a defective portion caused by the joint of the belt base and a defective portion caused by the joint of the coating film. The defective portion 24 is provided.

The resistance value when the obtained endless belt is used as a transfer belt is preferably about 10 ⁵ to 10 ¹³ Ωcm in terms of volume resistivity and about 10 ⁸ to 10 ¹² Ω / □ in terms of surface resistivity.

  When the obtained endless belt is used as a photosensitive belt, a photosensitive layer may be formed on the endless belt (semiconductive belt), but more preferably, a metal layer is provided on the surface to form an electrode. It is good to do. In this case, the endless belt may be insulative. As a method of providing a metal layer on the endless belt surface, vapor deposition or sputtering may be used, but there is also a method of applying ultrafine metal particles.

  Here, a method for forming a metal layer on the endless belt surface will be described. In order to improve the adhesion of the metal layer, the dry film of the film-forming resin solution is a solvent that dissolves the film in advance and is swelled or dissolved only on the surface before the metal layer is formed. Alternatively, the surface may be roughened. Further, the surface of the film may be chemically treated with an aqueous solution of acid / alkali, oxidizing agent / reducing agent or the like.

  The ultrafine metal particles refer to metal particles having a particle size of 1 nm to 100 nm, preferably 3 nm to 50 nm. When the metal is made to such a fine size, the melting point is lowered. This is because as the particle size decreases, the surface energy increases dramatically and attempts to bond (sinter) each other. Examples of metals that are preferably used include gold, silver, copper, nickel, palladium, indium, and platinum. The shape of the ultrafine particles is preferably spherical or an ellipsoid similar to a sphere.

  The melting point varies depending on the particle size, but also varies depending on the dispersion concentration in the dispersion medium, the type and concentration of the dispersant, and the like. A preferable melting point for producing the metal melt layer is 100 to 300 ° C.

  In addition to ultrafine particles, fine particles having a particle size of 0.1 μm or more and 10 μm or less may be used in combination. Although the fine particles have a low melting point, when the ultrafine particles are melted and sintered, the fine particles are also sintered at the same time. Therefore, the fine particles can be used as an extender and are effective for reducing the material cost. . The mixing ratio of the ultrafine particles and the fine particles is arbitrary, but the ultrafine particles need to be 5% by mass or more of the fine particles. The ultrafine particles and the fine particles may be the same metal or different metals, but in the case of different metals, it is preferable that they are easily fused to each other.

  The surface of the ultrafine particles may be coated with a resin or an additive. Examples of such a resin include an acrylic resin, a urethane resin, an epoxy resin, and a butyral resin. Examples of such additives include amine compounds, silicone compounds, coupling agents, and organic acids.

  The ultrafine metal particles are dispersed in a dispersion medium and applied. Examples of the dispersion medium include water and organic solvents such as alcohols, ketones, esters, and hydrocarbon compounds, and a plurality of types may be mixed. A surfactant or a thickener may be used for dispersion or dispersion stability.

  A small amount of binder resin may be used. The binder resin is preferably one that is separated or decomposed when the ultrafine metal particles melt and hardly remains in the metal layer. For example, acrylic resin, urethane resin, epoxy resin, butyral resin, polyethersulfone, polysulfone, Etc.

  10-60 mass% is preferable, and, as for the solid content concentration of a metal ultrafine particle dispersion liquid, More preferably, it is 12-55 mass%. The viscosity of the metal ultrafine particle dispersion is preferably 1 to 1000 mPa · s, more preferably 2 to 900 mPa · s or less. The thickness of the metal melt layer formed by applying ultrafine metal particles is preferably 0.01 to 10 μm or less, and more preferably 0.05 to 6 μm.

  The coating method is arbitrary, and in addition to the same slit coating as described above, since the film thickness is thin, spray coating, gravure coating, roll coating, and inkjet coating methods can also be employed. The seam that occurs during the application should match the seam of the endless belt.

  After the application, heating is performed at a temperature equal to or higher than the melting point, so that the ultrafine particles are sintered and a metal molten layer is formed. The melting temperature of the sintered metal layer becomes the original melting point of the metal and does not dissolve at the above temperature. During sintering, if the metal ultrafine particles are sintered and the PI precursor layer is imidized at the same time, the adhesion between the two becomes strong. That is, during imidization, a part of the metal constituting the metal layer formed on the surface of the PI precursor layer enters the PI precursor layer, and the PI precursor reacts in a state where the metal is taken in. It is considered that the adhesion between the layer and the PI resin layer is increased.

  When the metal constituting the metal melting layer is easily oxidized or denatured, such as copper or nickel, it is preferable to heat in an inert gas such as nitrogen or argon.

  The photosensitive belt is obtained by providing a photosensitive layer on a metal layer formed on the surface of an endless belt, and uses the metal layer as a ground electrode. You may add the electrode for conduction | electrical_connection to the edge part of a metal layer. Although it does not specifically limit as a photosensitive layer, For example, the OPC photosensitive layer which used organic substance as the photosensitive substance can be used.

  The OPC photosensitive layer can be either a single layer type or a laminated type composed of a function-separated charge generation layer and a charge transport layer. Further, an undercoat layer can be provided between the photosensitive layer and the substrate as necessary. Furthermore, a protective layer for protecting the photosensitive layer may be provided on the photosensitive layer. A known structure can be used for each of these layers.

  The undercoat layer may be, for example, a phenol resin, a urethane resin, a polyvinyl acetal resin, an alcohol-soluble nylon resin, or a copolymer thereof, or a curable metal organic compound (for example, a zirconium alkoxide compound, a titanium alkoxide compound, or a silane coupling). Agent or the like) is a layer formed by coating alone or in combination of two or more. In order to form the undercoat layer, the endless belt of the present invention is dip-coated in a coating solution for the undercoat layer and dried at 50 to 150 ° C. for 5 to 20 minutes. The thickness of the undercoat layer is preferably 0.1 μm to 5 μm.

  The charge generation layer (CGL) is formed, for example, by dispersing a charge generation agent (for example, phthalocyanine, perylene, bisazo pigment) in a binder resin (for example, polyvinyl butyral).

  CGL is formed by preparing a dispersion for CGL, applying it on the undercoat layer, and drying at 20 to 150 ° C. for 5 to 20 minutes. The thickness of CGL is preferably 0.01 μm or more and 1 μm or less.

  The charge transfer layer (CTL) includes a charge transport agent (for example, hydrazone compound, stilbene compound, benzidine compound, butadiene compound, triphenylamine compound, etc.) and a binder resin (for example, polycarbonate, polyarylate, polymethyl methacrylate, polyester, etc.). It is mixed and formed by coating.

  The CTL is formed by applying a coating solution for CTL onto the CGL and drying at 50 to 150 ° C. for 10 to 60 minutes. The thickness of the CTL is preferably 10 μm or more and 50 μm or less.

  Each of the above layers may be formed by an annular coating method or other known methods. When forming each layer, as disclosed in Japanese Patent Application Laid-Open No. 2003-337434, it is preferable to apply each layer on the endless belt without removing the endless belt on the core, and remove it from the core after all the layers are formed.

  Next, an image forming apparatus provided with an endless belt will be described. First, a case where an endless belt is applied as a photosensitive belt will be described. FIG. 5 is a schematic configuration diagram showing an example of the electrophotographic apparatus of the present invention.

  The electrophotographic apparatus shown in FIG. 5 is a color image forming apparatus and includes a photoreceptor belt 100. The photosensitive belt 100 is stretched around at least two drive rolls 110 and a backup roll 120.

  Further, around the photosensitive belt 100, a process unit 130 in which a charger 131, an exposure unit 132, and a developing unit 133 are integrally stored is disposed, and a transfer roll 140 is also disposed opposite to the backup roll 120. . In the electrophotographic apparatus shown in FIG. 5, four process units 130 are arranged for each color of black, cyan, magenta, and yellow. However, in the case of monochrome, one process unit 130 is sufficient.

  Here, a contact type or a non-contact type is used as the charger 131. Examples of the contact type include a charging roll and a charging brush. Examples of the non-contact type include a corotron, a scorotron, and a proximity charging roll. The exposure unit 132 is preferably an LED array for miniaturization. The developing device 133 includes a one-component type and a two-component type.

  In the electrophotographic apparatus shown in FIG. 5, the photosensitive belt 100 is charged by the charger 131, the image is exposed by the exposure device 132, and the toner is developed by the developing device 133. After the development of each color, the toner is transferred to the paper 150 by the transfer roll 140 and fixed on the paper by the fixing device 160. The fixing device 160 includes a pair of rotating bodies, either or both of which are rolls or belts.

  Although not shown, residual toner on the photosensitive belt 100 after the toner is transferred may be cleaned by a cleaning device, or the residual potential on the photosensitive belt 100 may be discharged by a static eliminator.

  Next, a case where the endless belt is applied as an intermediate transfer belt will be described. FIG. 6 is a schematic configuration diagram showing another example of the electrophotographic apparatus of the present invention.

  The electrophotographic apparatus shown in FIG. 6 is a tandem color image forming apparatus, and includes a transfer belt 200. The transfer belt 200 is stretched by at least two drive rolls 210 and backup rolls 220.

  Further, around the transfer belt 200, a process unit 230 in which a photosensitive drum 231, a charger 232, an exposure unit 233, and a developing unit 234 are integrally stored is disposed, and the primary unit is disposed so as to face the photosensitive drum 231. A secondary transfer roll 241 is also arranged opposite to the transfer roll 240 and the backup roll 220. In the process unit 230, a charger 232, an exposure device 233, and a developing device 234 are disposed around the photosensitive drum 231. In the electrophotographic apparatus shown in FIG. 6, four process units 230 are arranged for each color of black, cyan, magenta, and yellow. However, in the case of monochrome, only one process unit 230 is required.

  In the electrophotographic apparatus of FIG. 6, an image is formed on the photosensitive drum 231 by charging the photosensitive drum 231 with the charger 232, exposing the image with the exposure unit 233, and developing the toner with the developing unit 234. . After development, the toner is transferred to the transfer belt 200 by the primary transfer roll 240, subsequently transferred to the paper 250 by the secondary transfer roll 241, and fixed to the paper 250 by the fixing device 260.

  Although not shown, the photosensitive drum 231 after the toner has been transferred may be cleaned of residual toner by a cleaning device, or the residual potential on the photosensitive belt 100 may be discharged by a static eliminator.

  As described above, when an endless belt is applied to the photosensitive belt and the transfer belt of the electrophotographic apparatus described above, it is not preferable to form an image on a defective portion. Therefore, it is necessary to detect the position of the defective portion of the endless belt and perform image formation so as to remove it. In this case, the circumferential length of the endless belt may be equal to or longer than the length of the output image, specifically the length of the paper, and it may be controlled to remove the defective portion of the endless belt and perform image formation. If the circumferential length of the endless belt is made longer than the length of the output image (preferably twice or four times the length of the output image), there is little time waste for removing the defective portion of the endless belt.

  Hereinafter, the present invention will be described specifically by way of examples.

Example 1
As a film-forming resin solution, a polyimide precursor solution (trade name: U varnish S, manufactured by Ube Industries, solid concentration 18 mass%, viscosity of about 5 Pa · s, solvent N-methylpyrrolidone) was prepared.

  A stainless steel (SUS304) plate having a width of 400 mm and a thickness of 0.5 mm was rolled as a belt substrate, and both ends were joined by welding to produce a cylindrical body having an outer diameter of 366 mm. The seam was raised by welding, but was polished and polished to a thickness of about 0.8 mm to eliminate protrusions. The belt base produced in this way can be manufactured at a much lower cost than a cylindrical core made of a stainless steel cylinder.

  Next, a silicone release agent (trade name: Sepacoat, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface.

  A slit applicator provided with a slit having a width of 2 mm and a length of 24 mm was prepared. In the applicator, there is a liquid pool with an inner diameter of 15 mm at the tip of the slit, and the film-forming resin solution is fed into this from an external pump. The coating width was set to be 380 mm.

  Next, the belt base was fitted on a support roll having an outer diameter of 365 mm and rotated slowly at a peripheral speed of 1.5 rpm. When the belt base seam passed just below the slit of the applicator, the discharge of the solution was started from the slit. When the belt substrate was rotated once and the joint line was again directly below the slit of the applicator, the discharge of the solution from the slit was stopped and the coating was completed. At that time, there was no cut before and after the coating film.

  Thereafter, the belt substrate was removed from the support roll, and dried at 100 ° C. for 30 minutes while rotating at 10 rpm with its longitudinal direction horizontal, to form a PI precursor layer. Meanwhile, the seam before and after the coating was naturally smoothed to some extent. Subsequently, it heated at 250 degreeC for 30 minutes, and 350 degreeC for 30 minutes, and PI resin was made to react.

  After the belt substrate was cooled to room temperature, the PI resin film was removed to obtain a PI resin endless belt having a thickness of 75 μm. In the endless belt, a defective portion consisting of a seam of the coating film at the time of application is seen, but since it overlaps with a defective portion due to the transfer of the seam of the belt base, there is only one defective portion. Moreover, the thickness of the part was 70-80 micrometers, and it was not doubled like the case where the film | membrane was accumulated.

(Comparative Example 1)
In Example 1, when the seam of the coating film was not matched with the seam of the belt base during application, the obtained endless belt had a defect in which the seam of the belt base was transferred as a defective portion due to these. There are two disadvantages, namely, a defective portion due to the seam of the coating film at the time of application, and there are many ineffective portions.

(Example 2)
As a belt base, a stainless steel (SUS304) plate having a width of 400 mm and a thickness of 0.1 mm was rolled and joined at both ends by welding to produce a cylindrical body having an outer diameter of 366 mm. The seam was raised by welding, but was polished and polished to a thickness of about 0.8 mm to eliminate protrusions. Next, a silicone release agent (trade name: Sepacoat, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface.

  Next, the belt base was stretched on two support rolls having an outer diameter of 100 mm and rotated slowly at a peripheral speed of 1.5 rpm. The slit applicator is the same as in Example 1.

  As a film-forming resin solution, a polyimide precursor solution (trade name: U varnish A, manufactured by Ube Industries, solid concentration 18% by mass, viscosity of about 5 Pa · s, solvent N-methylpyrrolidone) was prepared. To this PI precursor solution, 23% by mass of carbon black (trade name: Special Black 4, manufactured by Degussa Huls Co., Ltd.) with respect to the solid content was added and dispersed with a counter collision type disperser. Using the solution, an endless belt was produced in the same manner as in Example 1.

The obtained belt had a semiconductivity of about 10 ¹⁰ Ωcm and a surface resistivity of about 10 ¹¹ Ω / □ at 100 V.

  This endless belt was cut into a width of 340 mm, and mounted on the electrophotographic apparatus shown in FIG. 6 as a transfer belt. When the image is formed, the transfer belt has a circumference of about 1150 mm. Therefore, it is possible to form an image for two sides of A3 paper having a length of about 420 mm and five sides of A4 paper having a length of about 210 mm. The transfer belt can be used effectively by providing a detection mark at the position of the defective portion of the transfer belt (endless belt) and controlling the detection mark to be a non-image forming portion.

(Comparative Example 2)
In Example 2, when an endless belt manufactured without matching seams in the same manner as in Comparative Example 1 is used as a transfer belt, there are two defective portions, so that it is difficult to control the non-image forming portion. is there. When the defective part entered the image, the defect part due to the transfer of the seam of the belt base became a tone pattern, and at the defective part due to the joint of the coating film at the time of application, there was a problem that density unevenness occurred before and after that. .

(Example 3)
In Example 1, on the surface of the PI precursor layer after drying, a dispersion of ultrafine silver particles (spherical particles having a particle size of 5 to 10 nm, melting point 200 ° C.) (Osaka Cement Co., Ltd., solid concentration 40 mass) %, Viscosity 3 mPa · s) was applied once by a gravure coating method. The seam at that time was matched with the seam of the PI precursor layer.

  Next, heating was performed in the same manner as in Example 1 to simultaneously imidize the PI resin and melt the silver layer. The volume resistivity of the silver layer was about 10 μΩcm and was conductive. Moreover, since each layer was produced by simultaneous heating, the adhesion was good.

  On the other hand, 1 part of polyvinyl butyral resin (BM1, manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 19 parts of cyclohexanone, and 3 parts of chlorogallium phthalocyanine was added thereto and dispersed by a sand mill to further add 20 parts of acetone. . This dispersion was used as a coating solution, and was coated once on the metal layer by a gravure coating method to form CGL having a thickness of 0.12 μm.

  Subsequently, 40 parts of N, N′-diphenyl-N, N ′-(m-tolyl) benzidine as a charge transport agent and a polycarbonate Z resin having a weight average molecular weight of 60,000 (Iupilon Z600, manufactured by Mitsubishi Gas Chemical Company) 60 Parts were dissolved in 200 parts of tetrahydrofuran. This coating solution was applied once on the CGL by a gravure coating method and dried at 135 ° C. for 40 minutes to form a CTL having a thickness of 20 μm. Thereafter, the film was removed from the belt substrate to obtain a flexible belt-like photoreceptor.

  When the adhesion of the photosensitive layer was investigated by the gobang eye peeling test using the cellophane tape for the produced photoreceptor belt, it was found that the adhesion of the metal layer was excellent, and thus the adhesion of the entire photosensitive layer was also excellent. .

  This photoreceptor belt was cut to a width of 340 mm and mounted on the electrophotographic apparatus shown in FIG. When an image was formed, the endless belt could be used effectively by controlling not to form an image on the defective portion of the photoreceptor belt (endless belt) as in Example 2.

・
From these examples, it can be seen that even when a resin endless belt is produced using a belt base having a seam, there is only one defective portion, and the endless belt has reduced waste during image formation. It can also be seen that the obtained endless belt does not increase the thickness of the defective portion and is preferably applied to a transfer belt or a photoreceptor belt.

It is a schematic block diagram which shows an example of the coating device of this invention. It is an enlarged view which shows an example of the joint of a belt base, (A) shows the case where a belt base is comprised with the resin film, (B) has shown the case where a belt base is comprised with the metal thin plate. It is a schematic block diagram which shows another example of the coating device of this invention. It is a perspective view which shows the endless belt obtained using the coating device of this invention. It is a schematic block diagram which shows an example of the electrophotographic apparatus of this invention. It is a schematic block diagram which shows another example of the electrophotographic apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Belt base | substrate 12 Support roll 14 Applicator 16 Slit 18 Puddle 20 Coating film 22 Endless belt 24 Defective part

Claims (6)

A coating device for continuously extruding a coating solution from a slit to a belt substrate surface having a seam;
The coating apparatus is characterized in that the coating start position is at or near the joint of the belt base. A coating method in which a coating solution is continuously extruded from a slit and applied to a belt substrate surface having a seam,
The coating method is characterized in that the coating start position is at or near the joint of the belt base. Applying the film-forming resin solution to the belt substrate having a seam by the coating method according to claim 2;
Heating the applied film-forming resin solution to form a resin film;
Removing the resin film from the belt substrate;
A process for producing an endless belt, comprising:   An endless belt obtained by the method for producing an endless belt according to claim 3.   The endless belt according to claim 4, wherein a defect portion caused by transfer by the joint of the belt base and a defect portion caused by a joint of the coating film at the start and end of coating overlap at the same position. .   An electrophotographic apparatus comprising the endless belt according to claim 4.

Images