JP5162857B2 - Manufacturing method of coated product, coating apparatus, and manufacturing method of parts for electrophotographic apparatus - Google Patents

Description

  The present invention relates to a method for manufacturing a coated product, a coating apparatus, and a method for manufacturing a part for an electrophotographic apparatus.

  Electrophotographic apparatuses have been widely put into practical use as copying machines, printers, and the like, but in recent years, their resolution and full color have been advanced. As for higher resolution, a resolution of 1200 dpi, which has been 600 dpi in the past, is now required. Further, the color is full color, and full color quality comparable to silver salt is required. In these high-resolution or full-color electrophotographic apparatuses, parts directly related to image formation are required to have higher quality than conventional products. For example, an electrophotographic photosensitive member is an important part that forms an electrostatic latent image, and then attaches toner to form a toner image. This defect directly affects the electrostatic latent image and the toner image. Therefore, it is required to be uniform and free from defects.

  Electrophotographic photoreceptors include inorganic photoreceptors using amorphous silicon and the like, and organic photoreceptors (hereinafter abbreviated as OPC) using organic optical semiconductors. Organic photoreceptors are widely used because they can be produced by applying a photoreceptor material to a photoreceptor substrate, and the characteristics can be controlled by the composition of the coating film and the components and thickness of each coating film. In general, the electrophotographic photosensitive member is produced as follows. First, there is a cleaning step of cleaning the cylindrical conductive substrate cut to a predetermined length, and here, impurities such as oil and chips during cutting are removed. Usually, the cleaning step is performed with an aqueous cleaning solution. After cleaning, a drying process is provided to remove moisture remaining on the surface of the conductive substrate. Subsequently, there is a step of forming an undercoat layer, a photosensitive layer, a protective layer, etc. on the outer peripheral surface of the washed and dried conductive substrate. In forming each layer, a photosensitive material dissolved in a solvent is generally used. As a coating method for applying an undercoat layer, a photosensitive layer, a protective layer and the like to the outer peripheral surface of a conductive substrate, a dip coating method, a ring coating method, a spray coating method and the like are known.

  In the production of an electrophotographic photosensitive member, a spray coating method is often applied from the viewpoint of simplicity of the apparatus and adaptability to multi-product production. For example, according to Patent Document 1, it is possible to eliminate coating unevenness by fixing spray in spray coating, moving the object to be coated, and spray coating while rotating. According to Patent Document 2, the inside of a coating booth in spray coating is evacuated, and the surface of an object to be coated placed in the coating booth is dusted beforehand by air spray or the like before coating. As a result, the coating quality of the coated surface is improved.

However, in the spray coating method, some of the sprayed droplets do not adhere to the coating, and the use efficiency of the coating liquid is often lowered. As a spray coating method for improving the utilization efficiency of the coating liquid, an electrostatic spray coating method is known. In the electrostatic spray coating method, fine particles of the charged coating liquid are sprayed to generate an attractive force by electrostatic force between the fine particles of the charged coating liquid and the object to be coated. It is a method to work. Thereby, the adhesion efficiency of the coating liquid can be improved. Patent Document 3 discloses an electrostatic spray coating method in which paint is atomized by a rotating plate and sprayed on a coated object. Patent Document 4 discloses an electrostatic spray coating method for forming a coating surface having a uniform film thickness on a rotating cylindrical workpiece. The electrostatic spray coating method improves the adhesion efficiency of paint to the object to be coated, but sparks are generated between the coating liquid particles charged by electrostatic spray and the object to be coated and the spray coating booth. Easy to do. Usually, an organic solvent is used in the coating liquid of the electrostatic spray coating method, and the inside of the coating booth has a flammable atmosphere, which increases the risk of causing a flammable explosion due to a spark. In general, when using electrostatic spray, to avoid such danger, the work piece or spray coating booth is grounded, but to ensure safety such as poor grounding and possible short circuit. I had to be careful. In addition, in the electrostatic spray coating method, if the distance between the spray gun and the object to be coated is shortened, the electrostatic field formed between the spray gun and the object to be coated becomes stronger, so that the adhesion efficiency of the coating liquid can be improved. The speed of the coating liquid that reaches the coated product becomes too high, and there is a problem that the coating film unevenness occurs and the quality of the coating is not stable, and it is difficult to balance the use efficiency of the coating and the product quality assurance. Further, if the distance between the spray gun and the object to be coated is too short, there is a safety problem that a short circuit occurs between the spray gun and the object to be coated.
JP 2003-122035 A JP 2006-65149 A Japanese Patent Application Laid-Open No. 62-6172 Japanese Patent No. 3166270

  An object of the present invention is to provide a method for producing a coated product such as a part for an electrophotographic apparatus by an electrostatic spray coating method that ensures excellent coating film quality and avoids dangers such as explosion and fire, and electrostatic spray coating. It is to provide a painting device by a construction method.

  Means for solving the problems in the present invention are as follows.

The present invention is a method for manufacturing a coated product in which a coating object is spray-coated in a coating booth, and a voltage of −50 kV or more and −15 kV or less is applied by an electrostatic spray gun while moving the coating surface of the coating object. Spraying the charged coating liquid particles onto the coating surface, forming an air flow in a direction substantially parallel to the spraying direction of the coating liquid particles in the coating booth, and being disposed across the object to be coated, In the method for producing a coated product, the air flow is rectified by a rectifying plate having a narrower interval on the downstream side than the upstream side of the air flow, and the object to be coated is spray-coated in the air flow .

Preferred invention is said coated product manufacturing method for spray coating the velocity of the air current of the coated surface near as below 0.2 m / sec or more 1 m / sec.

A preferred aspect of the present invention is the method for manufacturing a coated product, wherein gas is supplied to the coating booth by a gas supply device having an intake side pressure of 0.01 MPa or more and 0.2 MPa or less to form an air flow.

A preferred aspect of the present invention is the method for producing a coated product, wherein the oxygen concentration in the coating booth is 10% by volume or less.

Preferred invention is said method for manufacturing a coated article for supplying nitrogen from the upstream side of the air flow within the coating booth during spray coating.

A preferred aspect of the present invention is the method for producing a coated product, wherein the concentration of nitrogen supplied from the upstream side of the airflow in the coating booth is 95% by volume or more.

A preferable aspect of the present invention is the method for producing a coated product, wherein an interval between the spray port of the electrostatic spray gun and the coating surface is 100 mm or more and 200 mm or less.

The present invention includes a coating booth for spray coating an object to be coated, a supporting means for supporting the object to be coated in the coating booth and moving the coated surface of the object to be coated, and −50 kV or more to −15 kV An electrostatic spray gun that sprays the coating liquid particles charged by applying the following voltage to the coating surface and an air flow in a direction substantially parallel to the spray direction of the coating liquid particles are formed, and A gas supply device for spray-coating a coating object and the coating booth are arranged with the object to be coated interposed therebetween, and the air flow is rectified by narrowing the interval downstream from the upstream side of the air flow. And a current plate .

Preferred invention is said coating apparatus equipped with an exhaust system for discharging the gas in the coating booth.

Preferably, in the present invention, the gas supply device includes a gas supply tank containing a gas having a pressure of 0.01 MPa or more and 0.2 MPa or less, and sucks the gas from the gas supply tank and supplies the gas into the coating booth. It is the said coating apparatus which has a blower for gas supply to perform.

Preferred invention, the distance between the rectifying plate and the object to be coated, which is the coating apparatus which can be made 40mm or 100mm or less.

Preferred invention, the rectifying plate is the coating apparatus comprising a conductive material.

Preferred invention, the rectifying plate is the possible adjustment of the detachable and attachment angle of the coating booth said coating device.

According to a preferred embodiment of the present invention, the object to be coated is a cylindrical body disposed below the electrostatic spray gun, the central axis of the cylindrical body is supported so as to be substantially horizontal, and the central axis of the cylindrical body is the center. A support means for rotating, the spray direction of the electrostatic spray gun has an inclination of 3 ° or more and 6 ° or less with respect to the downward vertical direction, and represents the spray direction of the electrostatic spray gun. the intersection of the outer surface of the center line between the cylinder outer surface of the cylindrical body when the cylindrical body is rotated is the coating apparatus in a position going down downward.

In a preferred aspect of the present invention, the intersection of the injection center line representing the injection direction of the electrostatic spray gun and the outer surface of the cylindrical body is at a distance of 7 mm or more and 13 mm or less from a vertical plane including the central axis of the cylindrical body. is there the coating apparatus.

Preferred invention, the supporting means is a said coating apparatus capable of rotating the cylindrical body inclusive 130 rpm 180 rpm.

A preferred embodiment of the present invention is a method for producing a part for an electrophotographic apparatus in which a coating solution is applied to the surface of a substrate of the part for an electrophotographic apparatus using any one of the coating apparatuses .

According to the method for producing a coated product of the present invention , it is possible to provide a method for producing a coated product by an electrostatic spray coating method that ensures coating film quality and avoids dangers such as explosion and fire. In particular, the preferred method for producing a coated product of the present invention is suitable for producing a coated product having excellent coating film quality, and the preferred method for producing a coated product of the present invention is a static method that avoids dangers such as explosion and fire. to reach suitable for the production of coated product due to electrostatic spray coating method.

According to the coating apparatus of the present invention , it is possible to provide a coating apparatus that ensures coating film quality and avoids dangers such as explosion and fire. Particularly preferred coating apparatus of the present invention, there is coating apparatus suitable for the manufacture of coated product having excellent coating quality, preferably the coating apparatus of the present invention, an electrostatic to avoid explosion, fire hazard, etc. There are coating equipment suitable for the manufacture of coated products by spray coating. The preferred coating apparatus of the present invention, there is coating apparatus suitable for the manufacture of paint utilization efficient painted. Furthermore, according to the method for producing a part for an electrophotographic apparatus of the present invention , a high-quality part for an electrophotographic apparatus can be produced safely.

  Embodiments of the present invention will be described with reference to the drawings.

  In the method for manufacturing a coated product according to the present invention, in the method for manufacturing a coated product in which a coating object is spray-coated in a coating booth, the coating sprayed by an electrostatic spray gun while moving the coating surface of the coating material. This is a method for producing a coated product in which a voltage of −50 kV or more and −15 kV or less, preferably −40 kV or more and −20 kV or less is applied to a liquid particle to be charged and sprayed onto a coated surface. The structure of the coating apparatus for implement | achieving this manufacturing method of a coated article is illustrated in FIG. In a coating apparatus 26 shown in FIG. 1, a cylindrical coating object 2, for example, a photosensitive body for an electrophotographic apparatus, is installed in a spray coating booth 1, and a supporting apparatus 3 that rotates while supporting it. And an electrostatic spray gun 4 that sprays the coating liquid while moving in parallel with the axis of the workpiece 2. The electrostatic spray gun 4 includes a coating liquid tank 7 for supplying a coating liquid, a liquid feed pump 8, and a spraying gas supply device 9 for atomizing and spraying the supplied coating liquid. Spray coating is performed by the electrostatic spray gun 4 to form a coating film on the outer peripheral surface of the object to be coated 2 to produce a coated product.

  Here, the electrostatic spray gun 4 is an electrostatic spray gun. The electrostatic spray gun includes a voltage application device 5 and a voltage conversion controller 6. Usually, the voltage application device 5 applies a negative voltage to the ground voltage. In the present invention, a voltage of −50 to −15 kV, preferably −20 to −40 kV is applied to the tip 22 of the spray nozzle of the electrostatic spray gun 4 (see FIG. 7), and the spray of the electrostatic spray gun 4 is applied. When the coating liquid is sprayed from the tip 22 of the nozzle toward the workpiece 2, the sprayed coating liquid particles are sprayed with the above-described negative charge. On the other hand, if the workpiece 2 is grounded via the support device 3 or the like, an electrostatic field of −50 to −15 kV is generated between the workpiece 2 and the coating liquid particles. Due to the attractive force of the electrostatic field, the coating liquid particles adhere to the workpiece 2 so as to be sucked. For this reason, the electrostatic spray coating has a very high utilization efficiency of the coating liquid compared to the ordinary spray coating. By applying the electrostatic spray coating method, even with an expensive coating liquid, the coating efficiency can be increased and the coating liquid cost can be reduced to ½ or less. If the applied voltage for charging the coating liquid particles is too lower than −50 kV (potential difference from the ground voltage is too large), the adhesion attractive force is increased too much, and coating film unevenness is likely to occur, resulting in poor coating film quality. If the applied voltage is too higher than −15 kV (the potential difference from the ground voltage is too small), the electrostatic force is weakened and the adhesion efficiency is deteriorated. On the other hand, if the applied voltage is too lower than −50 kV, the risk of ignition explosion due to electrostatic spark increases.

  As a preferred embodiment of the present invention, in the above-described coating method, there is a method in which an air flow in a flow direction substantially parallel to the spray direction of the coating liquid particles is formed in the coating booth, and spray coating is performed in this air flow. As shown in FIG. 2, in the coating liquid particles or coating liquid that could not be applied to the workpiece 2 by flowing fresh gas from the upstream side to the downstream side with respect to the injection direction 10 of the electrostatic spray gun. It is possible to prevent flammable substances such as solvents contained from staying. This can reduce the risk of explosion and fire. In addition, by forming the above-mentioned air flow in the coating booth, the coating liquid particles that could not adhere normally to the coating object stay in the coating booth and are intended for the drying process of the coating object. It is possible to prevent adhesion to the object to be coated and to cause abnormal coating. FIG. 2 shows the injection direction of the electrostatic spray gun in the coating apparatus of the present invention by arrows, and the direction of airflow formation is also the same direction as this arrow. Note that the direction of the airflow is not strict, and in the same direction as the arrow indicating the spray direction in FIG. 2 in the vicinity of the coating object, from the upstream side of the coating nozzle 4 to the downstream side of the coating object 2. Just go to. In reality, the gas in the vicinity of the injection nozzle of the coating nozzle or in the vicinity of the object to be coated cannot flow strictly in the direction of the arrow indicating the spray direction. For example, as shown in FIG. 6, gas is accompanied by rotation of the object to be coated. The airflow in the flow direction substantially parallel to the spraying direction of the coating liquid particles here means that the coating liquid particles that cannot be normally adhered to the coating object among the coating liquid particles sprayed from the coating nozzle are not retained. As long as the airflow can be removed by placing it on the airflow. The spray direction of the electrostatic spray gun is a direction in which the coating liquid particles travel on a conical central axis formed by the sprayed coating liquid particles.

  In forming the airflow, the flow velocity of the airflow in the vicinity of the coating surface is preferably 0.2 m / second or more and 1 m / second or less, and preferably 0.3 m / second or more and 0.6 m / second or less. If the flow velocity of the airflow is slower than 0.2 m / sec, the above-mentioned effect of removing the coating liquid particles is insufficient, and if it is earlier than 1 m / sec, the coating liquid particles that should normally adhere to the coating surface are flowed by the airflow, Since it cannot adhere to the coated surface, the utilization efficiency of the coating liquid may decrease. By setting the flow velocity of the airflow within the above range, the airflow around the work piece can be prevented from being rolled up and rectified, and adheres to the work piece drifting around the work piece that occurs during spray coating. The overmist that did not exist can be efficiently flowed to the exhaust port side, and coating film defects can be reduced.

  Usually, in order to form an airflow, it is preferable to install a gas supply device upstream of the airflow in the coating booth. The gas supply device may be a high pressure gas direct supply device such as a high pressure cylinder or a gas supply blower. In the case of a gas supply blower, the intake side pressure is preferably set to 0.01 MPa or more and 0.2 MPa or less. By setting the pressure on the intake side of the gas supply blower to 0.01 MPa or more and 0.2 MPa or less, pulsation of the air current in the coating booth where the gas is supplied is prevented, and 0. An airflow having a flow velocity of 2 m / sec or more and 1 m / sec or less can be formed.

  As an aspect for suppressing the risk of flammable explosion in the coating booth, there is the above-described electrostatic spray coating method in which the oxygen concentration in the coating booth is 10% by volume or less, preferably 5% or less. If the oxygen concentration is 10% or less, preferably 5% or less, no explosion or fire occurs even when the electrostatic spark generated in the air reaches the ignition energy that can be the ignition source when electrostatic coating is applied. There is a case. This method reduces the amount of oxygen, which is one of the three principles of ignition and explosion, oxygen, ignition source, and combustible material. If the normal oxygen concentration is about 21%, the minimum ignition energy is 0.1 mJ-1 Even if a general coating solvent of about 0.0 mJ is used as a dilution solvent of the coating liquid, ignition is prevented. For example, in an environment where the oxygen concentration is 10% or less, the minimum ignition energy is often 1 mJ even with the solvent. If electrostatic spray coating is performed with the applied voltage in the present invention, the energy of electrostatic sparks of 1 mJ or more is rarely generated, and the danger of poor explosion is eliminated. As a specific method for setting the oxygen concentration in the coating booth to 10% by volume or less, for example, nitrogen from the upstream side of the air flow in the coating booth during spray coating, preferably the nitrogen concentration is 95% by volume or more, more preferably There is a method of supplying high concentration nitrogen of 99% by volume or more. If the purity of the nitrogen gas supplied into the coating booth is 95% by volume or more, preferably 99% by volume or more, the oxygen concentration in the coating booth 1 can be maintained at 10% or less, preferably 5% or less. Spark energy due to static electricity generated during painting cannot be a source of ignition energy such as solvent, preventing explosion and fire.

  FIG. 3 shows a coating apparatus of the present invention provided with an air supply blower and an exhaust fan. In the coating booth 1, this coating apparatus has an air supply port 11 on the upstream side with respect to the spray direction 10 and an exhaust port 12 on the downstream side with respect to the spray direction 10. An air supply blower 18 is attached to the air supply port 11. An exhaust fan 19 is attached to the exhaust port 12. An air supply port 11 is provided on the upstream side with respect to the spray direction 10 and an exhaust port 12 is provided on the downstream side with respect to the spray direction 10, and an air supply blower 18 and an exhaust fan 19 are additionally provided. Overmist that has not adhered to the coated material can be efficiently removed together with the exhaust, and the interior of the coating booth can be kept clean. In this way, the degree of cleanliness in the coating booth can be achieved to a class of 100 or less at the time of non-coating.

  Usually, in the manufacturing method of the coated article of this invention, after apply | coating in a coating booth, the applied coating film is dried. The drying of the coating film often takes a longer time than spray coating, and it is not economical to continue supplying nitrogen into the coating booth during this time. Therefore, it is preferable that the supply of nitrogen is stopped when the spraying of the coating liquid that causes a fire explosion ends and the process moves from the coating process to the drying process. By supplying nitrogen gas only during spray coating, the nitrogen supply amount can be reduced by 50% or more, the nitrogen supply device itself can be downsized, and the investment amount of the nitrogen supply device can be reduced to half or less.

  The distance between the spray nozzle at the tip of the spray nozzle of the electrostatic spray gun and the coating surface is desirably 100 mm or more and 200 mm or less, preferably 110 mm or more and 150 mm mm or less. When the distance 23 from the spray nozzle tip 22 of the spray nozzle of the electrostatic spray gun shown in FIG. 7 to the coating surface of the workpiece 2 is closer than 100 mm, the film quality of the coating film becomes rough and the film thickness varies. It becomes larger and the coating quality deteriorates. Further, there is a possibility that electric discharge occurs between the charged electrode portion at the tip 22 of the spray nozzle and the workpiece 2, which causes a safety problem. Further, if the distance 23 from the spray nozzle at the tip 22 of the spray nozzle to the coating surface of the workpiece 2 is longer than 200 mm, the coating liquid particle deposition efficiency is lowered, which is uneconomical.

  The coating apparatus of the present invention includes a coating booth for spray coating an object to be coated, a moving means for supporting the coated object in the coating booth and moving the coated surface of the coated object, and −50 kV or more to −15 kV An electrostatic spray gun that sprays coating liquid particles charged by applying the following voltage onto the coated surface; A preferred coating apparatus of the present invention is a gas supply device for supplying a gas for forming an air flow in a flow direction parallel to the spraying direction of the electrostatic spray gun in the coating booth, and discharges the gas in the coating booth. An exhaust device is provided. Furthermore, a preferable coating apparatus of the present invention includes a gas supply tank containing a gas having a pressure of 0.01 MPa or more and 0.2 MPa or less, and a gas that is sucked from the gas supply tank and supplied into the coating booth. A supply device.

  FIG. 4 shows a coating apparatus of the present invention which is a preferred embodiment for forming a nitrogen stream. In this coating apparatus, the supply gas supplied to the coating booth 1 may be air, but normally it is preferable to use nitrogen gas, so that the nitrogen gas generated by the nitrogen generator 20 and supplied from the nitrogen generator 20 is used. In the receiver tank 21, the pressure is reduced to 0.01 MPa to 0.2 MPa, preferably 0.01 MPa to 0.05 MPa, and is supplied to the coating booth 1 by the air supply blower 18. For this reason, the suction side of the air supply blower 18 can be set to 0.01 MPa to 0.2 MPa, preferably 0.01 MPa to 0.05 MPa. If the intake air of the air supply blower 18 is set in this way, the discharge pressure of the air supply blower 18 is stabilized, and stable nitrogen gas without pulsation can always be supplied into the coating booth 1, which is caused by the pulsation of the airflow. It is possible to prevent coating film defects due to overmisting in the coating booth and re-adhesion to the object to be coated.

  8 and 9 show a configuration example of a preferred coating apparatus of the present invention. The coating apparatus in FIG. 8 is a view from above, and the article 2 is assumed to be a cylindrical electrophotographic photosensitive member. A nitrogen generator 20 for supplying nitrogen from the right side of the coating booth 1, that is, the upstream side of the airflow, a receiver tank 21, and an air supply blower 18 are provided. An exhaust fan 19 is provided on the downstream side of the airflow coating booth 1. The electrostatic spray gun 4 is arranged so as to spray the coating liquid on the coating surface of the workpiece 2 from the right side of the workpiece 2, that is, from the upstream side of the airflow. The coating object 2 rotates around a cylindrical axis, and the electrostatic spray gun 4 is a coating booth so that the entire outer surface of the cylindrical coating object 2 can be coated from top to bottom in the figure. The inside of 1 can be moved up and down. Thus, the entire outer surface of the cylindrical object to be coated can be applied by moving the object to be coated 2 and the electrostatic spray gun 4.

  In the coating apparatus of this invention, in order to arrange the flow direction of the airflow in a coating booth, it is preferable to provide a baffle plate in a coating booth. FIG. 9 is a view of the coating booth 1 in FIG. 8 as viewed from the upper part of the drawing (in the direction of the arrow A), that is, the inside of the workpiece 2 from the axial direction of the cylinder. As can be seen from FIG. 9, the two rectifying plates 13 are arranged with the object to be coated interposed therebetween, and the distance between the two rectifying plates 13 is narrower on the downstream side than on the upstream side of the airflow. In addition, this baffle plate 13 can be attached or detached, and the distance of the space | interval 16 in the supply gas downstream side can be changed. The rectifying plate 13 is preferably 40 mm or more and 100 mm or less in distance from the object to be coated 2 for airflow to flow, and more preferably the rectifying plate 13 made of a conductive material. Such a rectifying plate 13 is preferably attachable to and detachable from the coating booth 1 and adjustment of the mounting angle.

  5, 6, and 9 are explanatory diagrams of the current plate provided in the coating booth. These drawings are, for example, views of the inside of the coating booth 1 shown in FIG. 3 as viewed from above. In these figures, when a cylindrical coating object 2 is installed in the coating booth 1 and a coating film is formed on the surface of the coating object 2 while rotating it, the cylinder of the coating object 2 is used. Two rectifying plates 13 are provided so as to sandwich the workpiece 2 at a position parallel to the axis. 5 and 6, the electrostatic spray gun is not shown, but it is on the right side of the figure, and the right side is the upstream side of the airflow. By providing the rectifying plate 13, the air flow in the coating booth 1 can be rectified, and the flow velocity of the air flow between the workpiece 2 and the rectifying plate 13 can be rectified with a small amount of supplied air. .

  The ratio of the distance 15 between the rectifying plates on the upstream side of the air flow shown in FIG. 5 to the distance 16 between the rectifying plates on the downstream side of the air flow is 1.5 to 1 to 3 to 1, preferably approximately 2 to 1. Is desirable. By setting this ratio to 1.5 to 1 to 3 to 1, preferably approximately 2 to 1, even if the flow velocity of the entire air in the coating booth is relatively slow, the current plate is around the workpiece 2. The effect of rectifying the airflow is increased, and the overmist that has not adhered to the coating object floating around the coating object 2 generated during spray coating can be efficiently discharged to the exhaust port side. Thereby, adhesion of the mist which is not intended to the to-be-coated article 2 can be prevented, and a coating film defect can be reduced. In addition, the danger of explosion due to the retention of solvents and the like can be prevented.

  FIG. 6 shows a state in which the airflow in the coating booth is disturbed by the airflow accompanying the rotation of the workpiece in the vicinity of the workpiece 2. In this case, when the distance between the current plate 13 and the workpiece 2 is 40 mm or more, preferably 60 mm or more, and 100 mm or less, preferably 80 mm or less, the vicinity of the coating object 2 generated by the rotation of the coating object 2 The overmist can be efficiently discharged to the exhaust port side without being affected by the turbulence of the airflow due to the accompanying airflow 17, and the coating film defect due to the reattachment of the overmist to the workpiece 2 can be reduced.

  In a preferred embodiment of the coating apparatus according to the present invention, the object to be coated is a cylindrical body disposed below the electrostatic spray gun, supports the central axis of the cylindrical body to be substantially horizontal, and It has a support that can be rotated around the central axis, and the center line representing the spray direction of the electrostatic spray gun has an inclination of 3 ° to 6 ° with respect to the downward vertical direction. There is a coating apparatus in which the intersection between the center line representing the injection direction of the electrospray gun and the outer surface of the cylindrical body is at a position where the outer surface of the cylindrical body descends downward when the cylindrical body rotates.

  FIG. 10 shows an example of the configuration of this coating apparatus. In FIG. 10, symbols are added for explanation when the coating liquid is applied onto the cylindrical workpiece 2 using the electrostatic spray gun 4. In this coating apparatus 26, the vertical relationship of the coating booth 1 is determined as shown in the figure. The upper part of the figure is the upper part of the coating booth 1. The object to be coated 2 is supported by a support device 3 (not shown) and is rotatable about the central axis O of the cylindrical body of the object to be coated 2. The article to be coated 2 is arranged so that the central axis O of the cylindrical body is in a substantially horizontal direction. The electrostatic spray gun 4 is above the workpiece 2 and is movable in parallel to the central axis O of the cylindrical body of the workpiece 2. Further, a clean gas such as air or nitrogen is supplied from the air supply blower 18 and exhausted from the lower side of the coating booth 1. The electrostatic spray gun 4 can be charged by atomizing the coating liquid and applying a voltage to the atomized coating liquid. The charged coating liquid particles are sprayed toward the cylindrical workpiece 2 to coat the outer surface of the workpiece 2. The object to be coated 2 is grounded, and since an electric field is formed between the coating liquid particles ejected from the electrostatic spray gun 4 and the object to be coated 2 and an electrostatic attractive force acts, the coating liquid particles are In addition to the spraying force, it is attracted to the workpiece 2 by electrostatic attraction, thereby improving the coating liquid adhesion efficiency. The voltage applied to the atomized coating liquid can be appropriately changed between −15 kV to −50 kV, preferably −20 kV to −40 kV, depending on the required adhesion efficiency of the coating liquid. is there.

In the coating apparatus shown in FIG. 10, rectifying plates 13 that rectify the airflow are installed on both the left and right sides of the cylindrical workpiece 2. The rectifying plate 13 has a width W ₂ on the downstream side that is narrower than a width W ₁ on the upstream side of the airflow. The rectifying plate 13 can suppress the generation of a turbulent flow and a stagnant portion of the airflow. Therefore, it is possible to suppress the re-adhesion of the coating liquid that has not adhered to the object to be coated 2 to the object to be coated 2, and the coating film quality and the yield of the object to be coated 2 are improved. Further, since the rectifying plate 13 has a structure in which the width is narrowed vertically downward, on the downstream side of the airflow, the flow velocity of the airflow increases and the movement speed of the sprayed coating liquid particles increases. Thereby, the adhesion efficiency of the coating liquid to the workpiece 2 can be improved.

  The material of the current plate 13 is not particularly limited, but is preferably made of a conductive material. Thereby, the electrification of the rectifying plate 13 due to the sprayed coating liquid can be suppressed. As a result, the occurrence of sparks and the like can be suppressed, and the safety of the painting process can be ensured. It is preferable that the current plate 13 is detachable and the attachment position and the attachment angle can be adjusted. For example, by providing attachment guides for a plurality of rectifying plates 13 on the side surface of the coating booth 1, the rectifying plates 13 can be attached and detached, and the attachment position and the attachment angle can be adjusted.

  In the present invention, the direction in which the electrostatic spray gun 4 sprays the charged coating liquid, that is, the spray direction corresponding to the center line direction of the conical shape formed by the sprayed coating liquid dragon, The substrate 2 is preferably inclined 3 ° to 6 ° in the rotational direction, more preferably 4 ° to 5 ° (this angle is represented by θ in FIG. 10). As a result, the spray pattern on the object to be coated 2 can be widened in a range not exceeding the outer diameter of the object to be coated 2, and the coating liquid is sprayed in such a range. Can be improved. When θ is less than 3 °, the spray pattern on the workpiece 2 may hardly spread. When θ exceeds 6 °, the spray pattern on the workpiece 2 may exceed the outer diameter of the cylindrical conductive substrate 1.

  In this coating apparatus, the intersection of the center line representing the spraying direction of the electrostatic spray gun 4 and the outer surface of the cylindrical body that is the workpiece 2 is the distance d from the vertical plane including the central axis of the cylindrical body. Is 7 mm or more, preferably 9 mm or more, 13 mm or less, preferably 11 mm or less. In this case, the intersection of the center line representing the spray direction of the electrostatic spray gun 4 and the outer surface of the cylindrical body that is the workpiece 2 is an electrostatic spray gun with respect to a vertical plane including the central axis of the cylindrical body. 4 is preferably on the same side as 4. Thereby, the spray pattern on the to-be-coated object 2 can be expanded in the range which does not exceed the outer diameter of the to-be-coated object 2. When the distance d is less than 7 mm, the spray pattern on the workpiece 2 may hardly spread. Moreover, when d exceeds 13 mm, the spray pattern on the workpiece 2 may exceed the outer diameter of the workpiece 2.

  In this invention, it is preferable that the rotation speed which the support apparatus 3 rotates the to-be-coated article 2 is 130-180 rpm, and it is further more preferable that it is 150-160 rpm. By doing in this way, generation | occurrence | production of the rolling-up by rotation of the to-be-coated object 2 of the airflow containing the coating liquid particle sprayed from the electrostatic spray gun 4 can be suppressed, and the surface to the to-be-coated object 2 can be suppressed. Uneven coating can be prevented. For this reason, it is excellent in the stability of the film thickness in the coating to the to-be-coated article 2, and can improve the coating-film quality. When the rotational speed of the workpiece 2 is less than 130 rpm, uneven coating tends to occur and the stability of the film thickness tends to decrease. When the rotational speed of the workpiece 2 exceeds 180 rpm, the coating is performed. The airflow is affected in the vicinity of the object 2, so that the airflow may roll up and the stability of the film thickness may be lowered.

  In the coating apparatus of the present invention, the distance l between the tip 22 of the spray nozzle that ejects the charged coating liquid from the electrostatic spray gun 4 and the coating surface of the workpiece 2 is 100 mm to 200 mm, preferably 110 mm to It is desirable to make it variable between 150 mm, more preferably between 120 mm and 130 mm. Thereby, the high coating-film stability of the coating formed in the to-be-coated article 2 is obtained. When the distance l between the tip 22 of the spray nozzle and the coating surface of the workpiece 2 is less than 100 mm, the sprayed coating liquid particles reach the workpiece 2 with a strong momentum, and the coating film If the distance l exceeds 200 mm, the use efficiency of the coating liquid on the workpiece 2 may be deteriorated.

  In the coating apparatus shown in FIG. 10, instead of moving the electrostatic spray gun 4 substantially parallel to the central axis O of the cylinder of the article 2 to be coated, a supporting device or other moving means is used to The coated object 2 may be rotated about the central axis O and may be moved along the direction of the central axis O. In this way, the entire outer surface of the article to be coated 2 can be applied without moving the electrostatic spray gun 4.

  Using the coating apparatus described above, the parts of the electrophotographic apparatus including the photosensitive member base of the electrophotographic apparatus and other parts to be coated are coated, so that the parts and other parts of the electrophotographic apparatus including the photosensitive member are coated. Product can be manufactured.

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to the examples shown below.

Example 1
15 parts by mass of alkyd resin (Beccosol 1307-60-EL (Dainippon Ink Chemical Co., Ltd.)) and 10 parts by mass of melamine resin (Super Becamine G-821-60 (Dainippon Ink Chemical Co., Ltd.)) It melt | dissolved in the mass part, 90 mass parts of titanium oxide powder (Typer CR-EL (made by Ishihara Sangyo Co., Ltd.)) was added to this, and it disperse | distributed for 12 hours with the ball mill, and created the dispersion liquid. This dispersion was taken out into a container and diluted with cyclohexanone so that the solid content was 25% by mass to prepare an undercoat layer coating liquid. This coating solution for the undercoat layer is applied to the outer surface of a cylindrical aluminum drum having a diameter of 80 mm, a length of 380 mm, and a thickness of 2 mm by a dip coating method. After coating, the coating liquid is dried at 130 ° C. for 20 minutes and has a film thickness of 8 An aluminum drum coated with an undercoat layer having a maximum film thickness difference of 0.4 μm and an effective image area of 2 μm was obtained.

  Next, 4 parts by mass of polyvinyl butyral resin (ESREC HL-S (manufactured by Sekisui Chemical Co., Ltd.)) is dissolved in 150 parts by mass of cyclohexanone, and 10 parts by mass of the trisazo pigment (1) represented by the following structural formula is added to this solution. After dispersion for 48 hours with a ball mill, 210 parts by mass of cyclohexanone was further added and dispersed for 3 hours to prepare a dispersion.

This dispersion was taken out into a container and diluted with cyclohexanone so that the solid content was 1.5% by mass to prepare a coating solution for a charge generation layer. The charge generation layer coating liquid is applied by dip coating on an aluminum drum coated with the undercoat layer, and then 130 ° C.
An aluminum drum coated with a charge generation layer having a transmittance of 4% at a wavelength of 690 nm and a maximum transmittance difference of 0.2% in the effective image area was obtained by drying for 20 minutes.

Next, 10 parts by mass of bisphenol A type polycarbonate resin and 0.002 parts by mass of silicon oil (KF-50 (manufactured by Shin-Etsu Chemical Co., Ltd.)) are dissolved in 83 parts by mass of tetrahydrofuran, and the charge shown in the following structural formula is dissolved therein. 8 parts by mass of the transport material (2) was added and dissolved, and diluted with cyclohexanone so that the solid content was 8% by mass to prepare a coating liquid for a charge transport layer.

  The coating liquid for charge transport layer thus obtained was applied on the aluminum drum coated with the charge generation layer by a spray coating method using an electrostatic spray coating apparatus having the configuration shown in FIGS. The coating conditions are described below.

Applied voltage to electrostatic spray nozzle 22: -40 KV
Air velocity from upstream to downstream near aluminum drum 2 in coating booth 1: 0.3 m / sec Oxygen concentration in coating booth 1: 5%
Nitrogen concentration in coating booth 1: 95%
Nitrogen gas supply to coating booth 1: Available only when spray coating (not when drying coating)
Nitrogen gas pressure in the receiver tank: 0.01 MPa
Distance between electrostatic spray nozzle 22 and surface to be coated: 110 mm
Presence or absence of the current plate 13 or material: stainless steel Ratio of the distance between the upstream side 15 and the distance between the downstream side 16 of the current plate 13: 2: 1
Distance 24: 80mm between rectifying plate 13 and aluminum drum 2
Rotating speed of aluminum drum 2: 80 rpm
Electrostatic spray 4 moving speed: 5 mm / sec Electrostatic spray 4 coating liquid discharge rate: 25 ml / min After electrostatic spray coating, it is dried in coating booth 1 at 130 ° C. for 20 minutes, film thickness 25 μm, effective A coated aluminum drum coated with a three-layer coating film having a charge transport layer having a maximum film thickness difference of 1.2 μm in the image region was produced. This coated aluminum drum can be used as an electrophotographic photosensitive member, and is used as an electrophotographic photosensitive member (1). Similarly, ten electrophotographic photosensitive members (1) for the electrophotographic photosensitive member of Example 1 were produced.

  In the measurement of the thickness of the undercoat layer and the charge transport layer of the electrophotographic photoreceptor (1) and the variation thereof, a single film is provided on each aluminum drum, and an eddy current film thickness measuring instrument ( The film thickness at 80 arbitrary measurement points was measured by Fischer), and the average value was the film thickness, and the difference between the maximum value and the minimum value was the maximum film thickness difference. For the transmittance and maximum transmittance difference of the charge generation layer, a single film was similarly provided on the transparent PET film, and the transmittance at 690 nm was measured at 60 arbitrary measurement points with a spectrophotometer. It was calculated as the difference between the value and the minimum value.

(Example 2)
Ten electrophotographic photoreceptors (2), which are coated aluminum drums, were produced in the same manner as in Example 1 except for the coating conditions for the charge transport layer shown below.
Applied voltage: -20KV
Air velocity from upstream to downstream in the vicinity of the aluminum drum 2 in the coating booth 1: 0.5 m / sec Oxygen concentration in the coating booth 1: 2%
Nitrogen concentration in coating booth 1: 98%
Nitrogen gas supply to coating booth 1: Available only when spray coating (not when drying coating)
Nitrogen gas pressure in receiver tank: 0.05 MPa
Distance between electrostatic spray nozzle 22 and surface to be coated: 150 mm
Distance 24: 60mm between current plate 13 and aluminum drum 2
The film thickness and the maximum film thickness difference of the obtained electrophotographic photosensitive member (2) were almost the same as those of the electrophotographic photosensitive member (1) of Example 1.

(Comparative Example 1)
Ten electrophotographic photosensitive members (3), which are coated aluminum drums, were produced in the same manner as in Example 1 except for the coating conditions for the charge transport layer shown below.

Applied voltage to electrostatic spray nozzle 22: -10 KV
Air velocity from upstream to downstream in the vicinity of aluminum drum 2 in coating booth 1: 0.1 m / sec Oxygen concentration in coating booth 1: 15%
Nitrogen concentration in coating booth 1: 85%
Nitrogen gas pressure in the receiver tank: 0.3 MPa
Distance between electrostatic spray nozzle 22 and surface to be coated: 200 mm
Ratio of the distance between the upstream side 15 and the distance between the downstream side 16 of the current plate 13: 1: 1
Distance 24: 150mm between current plate 13 and aluminum drum 2
The film thickness and the maximum film thickness difference of the obtained electrophotographic photosensitive member (3) were almost the same as those of the electrophotographic photosensitive member (1) of Example 1.

(Comparative Example 2)
Ten electrophotographic photosensitive members (4), which are coated aluminum drums, were produced in the same manner as in Example 1 except for the coating conditions for the charge transport layer shown below.
Applied voltage to electrostatic spray nozzle 22: -10 KV
Air velocity from upstream to downstream near the aluminum drum 2 in the coating booth 1: 1 m / sec Oxygen concentration in the coating booth 1: 10%
Nitrogen concentration in coating booth 1: 90%
Nitrogen gas supply to coating booth 1: Available only when spray coating (not when drying coating)
Nitrogen gas pressure in receiver tank: 0.25 MPa
Distance between electrostatic spray nozzle 22 and surface to be coated: 185 mm
Presence or absence of the current plate 13 or material: stainless steel Ratio of the distance between the upstream side 15 and the distance between the downstream side 16 of the current plate 13: 1.2: 1
Distance 24: 200mm between current plate 13 and aluminum drum 2
The film thickness and the maximum film thickness difference of the obtained electrophotographic photosensitive member (4) were almost the same as those of the electrophotographic photosensitive member (1) of Example 1.

(Evaluation of electrophotographic photoreceptors (1) to (4) obtained in Examples 1 and 2 and Comparative Examples 1 and 2)
Electrophotographic photosensitive member (1), electrophotographic photosensitive member (2), electrophotographic photosensitive member (3) and electrophotographic photosensitive member (4) obtained in Examples 1 and 2 and Comparatives 1 and 2 (coated aluminum drum) ) Using 10 units each as a photoconductor, using a remodeled machine (λ = 655 nm, 1200 dpi, beam spot 2.7 × 10 ⁻³ mm ² ) of Ricoh's full color laser printer IPSIO Color 5000, Image formation was performed and the quality of the image was judged visually. The halftone image is a 2 × 2 dot image. Table 1 shows the image evaluation results. As can be seen from Table 1, the electrophotographic photosensitive member (1) and the electrophotographic photosensitive member (2) produced according to Examples 1 and 2 of the present invention do not cause any abnormality and can be used as suitable photosensitive drums. However, more than half of the electrophotographic photoreceptors (3) and electrophotographic photoreceptors (4) produced according to Comparative Examples 1 and 2 showed abnormalities and were not suitable for use as photosensitive drums.

  The energy generated by the electrostatic spark in the electrostatic spray coating as in the present invention is about 0.24 mJ. As shown in Table 2, when the oxygen concentration in the coating booth during spray coating is set to less than 5%, which is a requirement of the present invention (Examples 1 and 2), ordinary solvents such as methyl ethyl ketone, cyclohexane, and tetrahydrofuran are used. The minimum required ignition energy for such as is said to be 1.0 mJ or more, and there is no danger of ignition explosion due to electrostatic sparks, and safe electrostatic spray coating is possible. On the other hand, in an atmosphere having an oxygen concentration of 10% or more (Comparative Examples 1 and 2), for example, the necessary minimum ignition energy for a general solvent such as methyl ethyl ketone, cyclohexane, and tetrahydrofuran is about 0.1 mJ to 1.0 mJ. is there. Therefore, it cannot be said in Comparative Examples 1 and 2 that there is no risk of a flammable explosion due to electrostatic sparks.

(Example 3)
Using the coating apparatus 26 shown in FIG. 1, an undercoat layer, a charge generation layer, and an outer surface of a cylindrical conductive substrate, which is an object to be coated 2 having an outer diameter of 100 mm and a total length of 360 mm, are applied by electrostatic spray coating, respectively. A charge transport layer was formed in order.

(Formation of undercoat layer)
The undercoat layer coating solution used was the same as in Example 1. Coating was performed by an electrostatic spray coating method. The conditions for electrostatic spray coating are described below.

Applied voltage to electrostatic spray nozzle 22: -35 KV
Air velocity from upstream to downstream in the vicinity of the aluminum drum 2 in the coating booth 1: 0.4 m / sec Distance between the electrostatic spray nozzle 22 and the surface to be coated: 120 mm
Presence or absence of the current plate 13 or material: stainless steel Ratio of the upstream space and the downstream space of the current plate 13: 2: 1
Tilt angle θ with respect to the vertical direction of the center line representing the spray direction of the electrostatic spray gun: 4 °
Distance d: 9 mm from the intersection of the center line representing the spray direction of the electrostatic spray gun and the outer surface of the object 2 to be coated and the vertical plane including the central axis of the cylinder of the object 2
Rotation speed of workpiece 2: 150 rpm
Electrostatic spray 4 moving speed: 2.5 mm / sec Coating liquid discharge amount of electrostatic spray 4: 6.0 ml / min Pressure of atomized air (compressed air) of electrostatic spray 4: 25 kPa
After the undercoat layer coating liquid was spray-coated on the object 2 to be coated, it was dried in the coating booth 1 at 130 ° C. for 20 minutes to form an undercoat layer. The inclination angle θ of the center line representing the spray direction of the electrostatic spray gun with respect to the vertical direction is the same as the rotation direction of the article 2 in the direction of rotation from the vertical line to the center line representing the spray direction of the electrostatic spray gun. The case is positive and the rotation angle in the opposite direction is negative. Further, the distance d from the intersection of the center line representing the spray direction of the electrostatic spray gun and the outer surface of the object 2 to the vertical plane including the central axis of the cylinder of the object 2 is such that the intersection is the object to be painted. The case of rotating down from the top of the cylinder of the object 2 is positive, and the case of going up toward the top of the cylinder of the object 2 is negative.

(Formation of charge generation layer)
10 parts by mass of the trisazo pigment (1) used in Example 1 was added to a solution in which 5 parts by mass of polyvinyl butyral resin S-LEC HL-S (manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 150 parts by mass of methyl ethyl ketone, and 48 hours by a ball mill. After the dispersion, the charge generation layer coating solution was prepared by diluting with cyclohexanone so that the solid content was 1.5% by mass. Using this charge generation layer coating, a charge generation layer was formed on the article 2 on which the undercoat layer was formed. A charge generation layer was formed in the same manner as the undercoat layer coating conditions including the drying conditions except that the undercoat layer coating conditions were changed as follows.

Electrostatic spray 4 moving speed: 12 mm / sec Coating liquid discharge amount of electrostatic spray 4: 5.0 ml / min Pressure of atomized air (compressed air) of electrostatic spray 4: 90 kPa
Thus, the article 2 to be coated on which the charge generation layer was formed was obtained.

(Formation of charge transport layer)
Using the charge transport layer coating liquid prepared in Example 1, a charge generation layer was formed on the object to be coated 2 on which the charge generation layer was formed. A charge generation layer was formed in the same manner as the undercoat layer coating conditions including the drying conditions except that the undercoat layer coating conditions were changed as follows.
Electrostatic spray 4 moving speed: 2.0 mm / sec Coating liquid discharge rate of electrostatic spray 4: 11 ml / min Pressure of atomized air (compressed air) of electrostatic spray 4: 45 kPa
As described above, an object to be coated on which an undercoat layer, a charge generation layer, and a charge generation layer were formed in order was obtained. An object to be coated on which the undercoat layer, the charge generation layer, and the charge generation layer are formed in this order is referred to as an electrophotographic photosensitive member (5). The electrophotographic photoreceptor (5) can be used as a photoreceptor. For evaluation, 50 electrophotographic photoreceptors (5) were prepared.

Example 4
An electrophotographic photoreceptor (6) was produced in the same manner as in Example 3 except that the coating conditions for the undercoat layer, the charge generation layer, and the charge transport layer were changed from Example 3 as follows.

Applied voltage to electrostatic spray nozzle 22: -40 KV
Air velocity from upstream to downstream in the vicinity of the aluminum drum 2 in the coating booth 1: 0.6 m / sec Distance between the electrostatic spray nozzle 22 and the surface to be coated: 130 mm
Tilt angle θ with respect to the vertical direction of the center line representing the spray direction of the electrostatic spray gun: 5 °
Distance d: 11 mm from the intersection of the center line representing the spray direction of the electrostatic spray gun and the outer surface of the object 2 to be coated to the vertical plane including the center axis of the cylinder of the object 2
Rotation speed of workpiece 2: 160 rpm
50 electrophotographic photoreceptors (6) were produced.

(Example 5)
An electrophotographic photoreceptor (7) was produced in the same manner as in Example 3, except that the coating conditions for the undercoat layer, the charge generation layer, and the charge transport layer were changed from Example 3 as follows.

Applied voltage to electrostatic spray nozzle 22: -40 KV
Air velocity from upstream to downstream in the vicinity of the aluminum drum 2 in the coating booth 1: 0.6 m / sec From the intersection of the center line representing the spray direction of the electrostatic spray gun and the outer surface of the workpiece 2 Distance d to the vertical plane including the central axis of the cylinder of the workpiece 2 d: 11 mm
50 electrophotographic photoreceptors (7) were produced.

(Example 6)
An electrophotographic photoreceptor (8) was produced in the same manner as in Example 3, except that the coating conditions for the undercoat layer, the charge generation layer, and the charge transport layer were changed from Example 3 as follows.

Applied voltage to electrostatic spray nozzle 22: -45 KV
Distance between electrostatic spray nozzle 22 and surface to be coated: 130 mm
Tilt angle θ with respect to the vertical direction of the center line representing the spray direction of the electrostatic spray gun: 5 °
Rotation speed of workpiece 2: 160 rpm
50 electrophotographic photoreceptors (8) were produced.

(Comparative Example 3)
An electrophotographic photoreceptor (9) was produced in the same manner as in Example 3, except that the coating conditions for the undercoat layer, the charge generation layer, and the charge transport layer were changed from Example 3 as follows.

Applied voltage to electrostatic spray nozzle 22: −0 KV
Distance between electrostatic spray nozzle 22 and surface to be coated: 180 mm
Presence / absence of the current plate 13 or material: nylon resin Inclination angle θ with respect to the vertical direction of the center line representing the spray direction of the electrostatic spray gun: 10 °
Distance d: 15 mm from the intersection of the center line representing the spraying direction of the electrostatic spray gun and the outer surface of the workpiece 2 to the vertical plane including the central axis of the cylinder of the workpiece 2
Rotation speed of workpiece 2: 80 rpm
50 electrophotographic photoreceptors (9) were produced.

(Comparative Example 4)
An electrophotographic photoreceptor (10) was produced in the same manner as in Example 3, except that the coating conditions for the undercoat layer, the charge generation layer, and the charge transport layer were changed from Example 3 as follows.

Applied voltage to electrostatic spray nozzle 22: 0 KV
Air velocity from upstream to downstream in the vicinity of the aluminum drum 2 in the coating booth 1: 0.6 m / second Distance between the electrostatic spray nozzle 22 and the surface to be coated: 80 mm
Presence or absence of current plate 13 or material: nylon resin Inclination angle θ with respect to the vertical direction of the center line representing the spray direction of the electrostatic spray gun: −5 °
Distance d: −9 mm from the intersection of the center line representing the spraying direction of the electrostatic spray gun and the outer surface of the object 2 to be coated and the vertical plane including the central axis of the cylinder of the object 2
Rotation speed of workpiece 2: 200 rpm
50 electrophotographic photoreceptors (10) were produced.

(Comparative Example 5)
An electrophotographic photoreceptor (11) was produced in the same manner as in Example 3, except that the coating conditions for the undercoat layer, the charge generation layer, and the charge transport layer were changed from Example 3 as follows.

Applied voltage to electrostatic spray nozzle 22: 0 KV
Air velocity from upstream to downstream in the vicinity of the aluminum drum 2 in the coating booth 1: 0.2 m / second Presence or absence of the current plate 13 or material: Nylon resin Center line indicating the spray direction of the electrostatic spray gun Tilt angle to the vertical direction θ: 2 °
Distance d: −11 mm from the intersection of the center line representing the spray direction of the electrostatic spray gun and the outer surface of the object 2 to be coated and the vertical plane including the central axis of the cylinder of the object 2
Rotation speed of workpiece 2: 160 rpm
50 electrophotographic photoreceptors (11) were produced.

(Comparative Example 6)
An electrophotographic photoreceptor (12) was produced in the same manner as in Example 3, except that the coating conditions for the undercoat layer, the charge generation layer, and the charge transport layer were changed from Example 3 as follows.

Applied voltage to electrostatic spray nozzle 22: 0 KV
Air velocity from upstream to downstream near the aluminum drum 2 in the coating booth 1: 1.2 m / sec Distance between the electrostatic spray nozzle 22 and the surface to be coated: 120 mm
Presence or absence of rectifying plate 13 or material: none 50 electrophotographic photosensitive members (12) were produced.

(Evaluation of electrophotographic photoreceptors (5) to (12) obtained in Examples 3 to 6 and Comparative Examples 3 to 6)
Using the electrophotographic photoreceptors (5) to (12) obtained in Examples 3 to 6 and Comparative Examples 3 to 6, the following (A) to (D) were evaluated.
(A) The average deposition efficiency (%) of the coating liquid was calculated from the amount of the coating liquid ejected during spray coating of the undercoat layer, the charge generation layer and the charge transport layer and the amount deposited on the electrophotographic photosensitive member.
(B) Using a clean air tracer and liquid nitrogen, the flow of nitrogen gas was visualized to visually confirm the presence of turbulent flow in the coating booth and the stagnant portion of the air flow.
(C) The produced electrophotographic photosensitive member was attached to a laser printer (manufactured by Ricoh Company), and the presence or absence of image defects on the print screen was confirmed. The number with image defects is the number out of 50 evaluations.
(D) Immediately after spraying the coating liquid, the charge amount of the rectifying plate 13 was measured with a static electricity meter.

  The above evaluation results are shown in Table 3.

  As can be seen from Table 3, the electrophotographic photoreceptors (5) to (8) in Examples 3 to 4 are the paints compared to the paints of the electrophotographic photoreceptors (9) to (12) in Comparative Examples 3 to 4. It is an economical coating method with a high average adhesion rate. In addition, there was no turbulent flow or airflow retention in the coating booth, and as a result, there were no image defects in the image test of the print screen using a laser printer. It was also found that the charging voltage of the rectifying plate was very low and the possibility of electrostatic sparks was low.

  The present invention can be suitably applied to the manufacture of a coated product by an electrostatic spray method, particularly to the manufacture of an electrophotographic photoreceptor.

Illustration of the configuration of the coating apparatus of the present invention Explanatory drawing of the spray direction in the coating apparatus of this invention Illustration of the configuration of the coating apparatus of the present invention Illustration of the configuration of the coating apparatus of the present invention Explanatory drawing of the baffle plate in the coating apparatus of this invention Explanatory drawing of the accompanying airflow in the coating apparatus of the present invention Explanatory drawing showing the distance between the spray nozzle and the coating surface Illustration of the configuration of the coating apparatus of the present invention Explanatory drawing of the coating booth in Fig. 3 as seen from the A direction Illustration of the configuration of the coating apparatus of the present invention

Explanation of symbols

1: Coating booth 2: Object to be coated 3: Support device 4: Electrostatic spray gun 5: Voltage application device 6: Voltage conversion controller 7: Coating liquid tank 8: Liquid feed pump 9: Spray gas supply device 10 : Arrow indicating the spraying direction of the spray nozzle 11: Air supply port 12: Exhaust port 13: Current flow plate 14: Air supply gas traveling direction 15: Spacing of the current flow plate on the upstream side of the air flow 16: Current flow on the current flow plate on the downstream side of the air flow Interval 17: An arrow indicating the airflow around the workpiece 18: Supply blower 19: Exhaust fan 20: Nitrogen generator 21: Receiver tank 22: Tip of spray nozzle 23: From tip of spray nozzle to coating surface Distance 24: Distance from the current plate to the object to be coated 25: Arrow indicating the rotation direction of the object to be coated 26: Coating apparatus (also referred to as coating apparatus)

Claims (17)

In the manufacturing method of the coated product that sprays the object to be coated in the coating booth,
Spraying coating liquid particles charged by applying a voltage of −50 kV to −15 kV with an electrostatic spray gun while moving the coated surface of the object to be coated ;
Forming an air flow in a direction substantially parallel to the spray direction of the coating liquid particles in the coating booth;
Arranged across the object to be coated, rectifies the airflow with a rectifying plate having a narrower interval on the downstream side than the upstream side of the airflow,
A method for producing a coated product, characterized in that the object to be coated is spray-coated in the air stream . The manufacturing method of the coated goods of Claim 1 which spray-coats by making the flow velocity of the airflow of the said coating surface vicinity into 0.2 m / sec or more and 1 m / sec or less. The manufacturing method of the coated goods of Claim 1 or 2 which forms gas flow by supplying gas to the said coating booth with the gas supply apparatus whose intake side pressure is 0.01 Mpa or more and 0.2 Mpa or less. The manufacturing method of the coated goods as described in any one of Claims 1 thru | or 3 which makes oxygen concentration in the said coating booth 10 volume% or less. The manufacturing method of the coated goods as described in any one of Claims 1 thru | or 4 which supplies nitrogen from the upstream of the airflow in the said coating booth at the time of spray coating. The manufacturing method of the coated goods of Claim 5 which makes the nitrogen concentration supplied from the upstream of the airflow in the said coating booth 95 volume% or more. The manufacturing method of the coated goods as described in any one of Claims 1 thru | or 6 which makes the space | interval of the spray port of the said electrostatic spray gun and the said coating surface 100 mm or more and 200 mm or less. A coating booth for spray coating the object to be coated,
A supporting means for supporting an object to be coated in the coating booth and moving a coated surface of the object to be coated;
An electrostatic spray gun that sprays coating liquid particles charged by applying a voltage of −50 kV or more and −15 kV or less onto the coated surface ;
A gas supply device for forming an air flow in a direction substantially parallel to the spray direction of the coating liquid particles, and spray coating the object to be coated in the air flow;
In the coating booth, arranged across the object to be coated, a rectifying plate that rectifies the air flow by narrowing the interval on the downstream side from the upstream side of the air flow, and
A painting device comprising: The coating apparatus of Claim 8 provided with the exhaust apparatus which discharges | emits the gas in the said coating booth. The gas supply device includes a gas supply tank containing a gas having a pressure of 0.01 MPa or more and 0.2 MPa or less, and a gas supply blower that sucks gas from the gas supply tank and supplies the gas into the coating booth. The coating apparatus according to claim 8 or 9 , comprising: Painting device according to any one of claims 8 to 10 interval is 40mm or more than 100mm between the rectifier plate and the object to be coated. The coating apparatus according to claim 8 , wherein the current plate is made of a conductive material. The said baffle plate is a coating apparatus as described in any one of Claims 8 thru | or 12 in which attachment or detachment to the said coating booth and adjustment of an attachment angle are possible. The object to be coated is a cylindrical body arranged below the electrostatic spray gun, and supports the central axis of the cylindrical body to be substantially horizontal, and supporting means for rotating about the central axis of the cylindrical body. And the injection direction of the electrostatic spray gun has an inclination of 3 ° or more and 6 ° or less with respect to the downward vertical direction, and the injection center line representing the injection direction of the electrostatic spray gun and the cylinder The coating apparatus according to any one of claims 8 to 13 , wherein an intersection with an outer surface of the body is at a position where the outer surface of the cylindrical body is lowered downward when the cylindrical body rotates. And the center line of the jet which represents the injection direction of the electrostatic spray gun, the intersection of the outer surface of the cylindrical body, to claim 14 at a distance of 7mm or more 13mm or less from the vertical plane including the central axis of the cylindrical body The coating equipment described. The coating apparatus according to claim 14 or 15 , wherein the support means can rotate the cylindrical body at 130 rpm or more and 180 rpm or less. A method for producing an electrophotographic apparatus part, wherein the coating apparatus according to any one of claims 8 to 16 is used to apply a coating liquid to a surface of a substrate of the electrophotographic apparatus part.

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