JP2011025196A - Dip application apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dip application apparatus which forms an application film efficiently on an application object body while suppressing uneven application or application defects. <P>SOLUTION: The dip application apparatus includes: an application tank 10; an application liquid supply part 20 for supplying an application liquid L to the application tank 10 so that the application liquid overflows the application tank 10; an application liquid recovery part 30 for recovering the overflowing application liquid L; and a circulation path 40 which connects the application liquid recovery part 30 to the application liquid supply part 20 to circulate the application liquid L. The application liquid supply part 20 includes: an application liquid tank 21 which is connected to the circulation path 40 and used for storing the application liquid L; a liquid supply path 22 through which the application liquid L is supplied from the application liquid tank 21 to the application tank 10; a pump 23 which is arranged in the liquid supply path 22 and used for supplying the application liquid L from the application liquid tank 21 to the application tank 10; a pressure detector 24 for detecting the discharge pressure of the pump 23; and a series route part 27 provided downstream from the pressure detector 24 in the liquid supply path 22 and formed by arranging a filter 25 and a flow rate regulating valve 26 in this order. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dip coating apparatus for forming a coating film on the surface of an object to be coated by immersing and lifting the object to be coated in a coating solution.

A dip coating method (also referred to as a dip coating method) is known as a method for forming a coating film by applying a coating solution on the surface of an object to be coated.
Examples of a film formed on the surface of an object to be coated using this dip coating method include a photoconductor provided in an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile.

This photoreceptor has a coated body (conductive support base) made of a metal such as aluminum, copper, or nickel, and a photosensitive layer made of an organic or inorganic material laminated on the outer peripheral surface of the coated body. As the photosensitive layer, an organic photosensitive layer is widely used in consideration of cost, freedom of material design, toxicity, and the like.
When forming an organic photosensitive layer using the dip coating method, the substrate is immersed in a coating tank filled with an organic photoreceptor coating solution, which is a material solution for the photosensitive layer, and then coated at a constant speed or an arbitrary speed. By pulling up the coated body, a photosensitive layer is formed on the outer peripheral surface of the coated body.

Photoconductors are always required to have stable performance and a high quality level, and this is especially true for photoconductors for full-color image forming apparatuses.
For this reason, defects such as coating unevenness that occurs when the photosensitive layer is formed on the outer peripheral surface of the object to be coated and the entry of minute foreign matter into the photosensitive layer are inspected more strictly than before, and rejected products are poorly manufactured. Become a drum. Furthermore, in order to reduce environmental burdens, protect resources, and reduce manufacturing costs, it is necessary to work on reduction of defective photoconductors and improvement of usability of coating solutions, as compared with the conventional case.

For this reason, as the dip coating method, many methods for reducing the occurrence of coating unevenness and coating defects and making the film thickness of the photosensitive layer uniform have been proposed. For example, the following prior arts 1 to 3 are mentioned. .
In prior art 1, in order to stabilize the flow rate of the coating liquid supplied from the coating liquid tank to the coating tank, the pump is controlled by an inverter, or a bypass piping system having a flow rate adjusting valve is provided to provide a coating liquid circulation supply flow rate. Is a dip coating method and apparatus for controlling (see, for example, Patent Document 1).

Prior art 2 has an air chamber between the pump and the coating tank in order to prevent uneven coating due to pulsation from the pump, and the pressure fluctuation of the coating liquid supplied from the recovery tank to the coating tank is ± 30 in gauge pressure. % Is a dip coating method and apparatus that prevents the occurrence of unevenness in the thickness of the coating film formed on the substrate to be coated locally (see, for example, Patent Document 2).
In Prior Art 3, in order to eliminate the pulsation derived from the pump and stabilize the flow rate of the coating liquid in the coating tank, the overflow liquid level of the coating liquid in the storage tank is held at a position higher than the overflow liquid level of the coating liquid in the coating tank. And a dip coating method and apparatus for circulating the coating liquid by flowing it into the coating tank from a position lower than the overflow liquid level on the storage tank side (see, for example, Patent Document 3).

Japanese Patent Application Laid-Open No. 7-209885 JP 2005-238145 A Japanese Patent Laid-Open No. 2006-320791

  In Prior Art 1, when a filter is provided in a supply piping system between a pump and a coating tank in order to remove foreign matters in the coating liquid that may cause a coating defect, the filter is supplied to the coating tank due to clogging of the filter. Although the flow rate of the coating liquid gradually decreases, the flow rate decrease due to filter clogging is not taken into account when adjusting the flow rate to be constant. Furthermore, in order to suppress a decrease in flow rate due to filter clogging, it is necessary to replace it with a new filter frequently. As a result, the production efficiency of the coating film formation on the coated body is greatly reduced, and each time the filter is replaced. There is a problem that the loss of the coating liquid generated in the process increases, leading to an increase in cost.

In the prior art 2, it is considered that the pulsation of the coating liquid caused by the pump, that is, it is effective in preventing coating unevenness due to the flow rate change within a certain range and stabilizing the flow rate (flow velocity). This is insufficient to stabilize the flow rate against a change in flow rate over time due to clogging of the filter provided between the chambers.
In the prior art 3, since it is necessary to provide a collection tank separately from the storage tank for supplying the coating liquid to the coating tank and to store the coating liquid in the collection tank, the use efficiency of the coating liquid is deteriorated. Further, since the dip coating apparatus becomes large and complicated, a wide installation place is required and the maintainability is also inferior. Furthermore, it is difficult to adjust the flow rate by adjusting the height of the storage tank.

  The present invention has been made in view of these problems, and can easily control the flow rate of the coating liquid to the coating tank while having a simple configuration, and can suppress uneven coating and coating defects, and can achieve stable quality. It is a main object of the present invention to provide a dip coating apparatus that can efficiently form a coating film on a substrate.

  Thus, according to the present invention, a coating tank for storing a coating liquid for immersing an object to be coated and forming a coating film on the surface thereof, and a coating liquid for supplying the coating liquid to the coating tank and causing the coating tank to overflow. A supply unit, a coating solution recovery unit for recovering the overflowed coating solution, a circulation path for circulating the coating solution overflowed from the coating solution recovery unit by connecting the coating solution recovery unit and the coating solution supply unit, The coating liquid supply unit is connected to the circulation path and stores the coating liquid tank, the supply liquid path for supplying the coating liquid from the coating liquid tank to the coating tank, the supply liquid path provided from the coating liquid tank A series path section in which a pump for supplying the coating liquid to the coating tank, a pressure detector for detecting the discharge pressure of the pump, and a filter and a flow rate adjusting valve are provided in this order on the downstream side of the pressure detector of the liquid supply path Immersion coating device with There is provided.

  According to another aspect of the present invention, there is provided a dip coating method using the dip coating apparatus, wherein a pump is driven to supply a coating liquid from a coating liquid tank to a coating tank, and an object to be coated and a coating tank And immersing the coated body in the coating liquid in the coating tank, and then lifting the coated body from the coating liquid to form a coating film on the surface of the coated body. , The degree of opening of the flow rate adjustment valve and the number of rotations of the pump so that the control pressure value exceeds the maximum pressure value of the discharge pressure change that occurs when the pump is maintained at the predetermined speed and the flow rate adjustment valve is kept fully open. Is initialized, and the pressure value detected by the pressure detector is managed to provide a dip coating method for managing the flow rate of the coating liquid supplied to the coating tank.

The present invention has the following effects.
(1) The dip coating apparatus of the present invention includes a pump that is provided in a liquid supply path and supplies a coating liquid from a coating liquid tank to a coating tank, a pressure detector that detects a discharge pressure of the pump, and a pressure in the liquid supply path A filter and a flow rate adjusting valve are provided on the downstream side of the detector, and a serial path portion is provided in this order. Therefore, the degree of opening of the flow rate adjustment valve and the rotation of the pump are adjusted so that the control pressure value is equal to or greater than the maximum pressure value of the discharge pressure change that occurs when the pump is maintained at a predetermined rotational speed and the flow rate adjustment valve is kept fully open. The number can be initialized.
As a result, the flow rate of the coating liquid supplied to the coating tank can be managed by managing the discharge pressure of the pump detected by the pressure detector.
More specifically, if the pump is kept at a predetermined rotation speed and the flow rate adjustment valve is kept fully open and the coating liquid continues to be circulated, the filter is clogged by foreign matter in the coating liquid (completely clogged). In this case, the predetermined flow rate cannot be obtained, and the discharge pressure at this time means the “maximum pressure value”.
In the present invention, in order to manage the flow rate of the coating liquid by managing a management pressure value that is equal to or greater than the maximum pressure value, the flow rate adjustment valve is previously throttled so that the discharge pressure becomes the management pressure value in the initial setting. Further, in the initial setting, the number of revolutions of the pump is set in advance so that the discharge pressure becomes the management pressure value.

This initial setting is to create a discharge pressure at or above the clogging of the filter (when it starts to drop below the specified flow rate) when the coating liquid is circulated. Therefore, the coating liquid is supplied to the coating tank at a predetermined flow rate, and the predetermined flow rate is maintained until the discharge pressure exceeds the management pressure value. During this time, adjustment of the flow rate adjustment valve and the pump is unnecessary.
On the other hand, when the discharge pressure starts to exceed the control pressure value even though the pump rotation number is kept constant, it indicates that the flow rate of the coating liquid has started to fall below the predetermined flow rate. This is a decrease in the flow rate due to the filter being clogged, and it is understood that it is time to replace the filter.
Therefore, the application process can be continued without replacing the filter until the discharge pressure exceeds the control pressure value.
As a result, the flow rate (supply amount) of the coating liquid to the coating tank due to filter clogging is prevented from being reduced, and a coating film with a stable quality with no coating defects and coating defects is formed on the coated body. Thus, the coating liquid can be supplied to the coating tank at a flow rate (supply amount).

(2) Since the filter and the flow rate adjusting valve are arranged in this order on the downstream side of the pressure detector, the differential pressure between the upstream pressure and the downstream pressure of the filter can be reduced to the same extent. The filter usability can be greatly improved.
In other words, when the filter is disposed downstream of the flow rate adjustment valve, the hydraulic pressure applied to the upstream side of the filter is significantly greater than the downstream hydraulic pressure, which causes the upstream side of the filter to be compressed and clogged. Although it becomes easy and the life is shortened, the differential pressure is reduced and the life of the filter can be extended by arranging the filter on the upstream side of the flow rate adjusting valve.
The effect of extending the service life can be obtained by both a disposable filter and a filter that can be washed and reused.

(3) Since the rotational speed of the pump is made higher than before, the pulsation derived from the pump can be kept smaller than before.
(4) In order to prevent a decrease in the flow rate of the coating liquid to the coating tank due to filter clogging, it is conceivable to use a variable output pump having a constant flow rate control function. It is possible to easily control the flow rate of the coating liquid to the coating tank using the constant power pump.

(5) In a conventional dip coating apparatus that does not monitor the discharge pressure of the pump, the output (rotation speed) of the pump is increased in order to prevent a decrease in the flow rate of the coating liquid to the coating tank due to filter clogging, or Since it is necessary to replace the filter with a new one, in the former case, a variable output pump is necessary, and in the latter case, the frequency of replacement of the filter increases, and the time required for the replacement work and loss of the coating liquid occur.
On the other hand, in the present invention, a general-purpose constant power pump can be used and the filter replacement frequency can be reduced. Therefore, the production efficiency of coating film formation on the coated body can be improved in terms of time and cost. Can greatly improve. In addition, the loss of coating liquid accompanying filter replacement can be reduced, contributing to resource conservation and environmental load reduction.

It is a schematic sectional drawing which shows Embodiment 1 of the dip coating apparatus which concerns on this invention. 1 is a longitudinal sectional view showing an electrophotographic photosensitive drum applicable to the present invention. It is a partial cross-sectional view showing various photosensitive drums applicable to the present invention. It is a schematic sectional drawing which shows Embodiment 2 of the dip coating apparatus which concerns on this invention. It is a schematic sectional drawing which shows Embodiment 3 of the dip coating apparatus which concerns on this invention.

  The dip coating apparatus according to the present invention includes a coating tank for storing a coating liquid for immersing an object to be coated and forming a coating film on the surface thereof, and a coating liquid for supplying the coating liquid to the coating tank and causing the coating tank to overflow. A supply unit, a coating solution recovery unit for recovering the overflowed coating solution, a circulation path for circulating the coating solution overflowed from the coating solution recovery unit by connecting the coating solution recovery unit and the coating solution supply unit, The coating liquid supply unit is connected to the circulation path and stores the coating liquid tank, the supply liquid path for supplying the coating liquid from the coating liquid tank to the coating tank, the supply liquid path provided from the coating liquid tank A series path section in which a pump for supplying the coating liquid to the coating tank, a pressure detector for detecting the discharge pressure of the pump, and a filter and a flow rate adjusting valve are provided in this order on the downstream side of the pressure detector of the liquid supply path With.

There are no particular restrictions on the substrate to which the coating liquid is applied using this dip coating apparatus and the shape thereof, and the coating liquid is a material liquid for the coating film to be formed on the surface of the cloth to be coated. Good.
In particular, it is suitable for use as a dip coating apparatus that is required to form a coating film having a uniform film thickness on the surface of the cloth to be clothed. One example of the coating liquid is a material liquid for forming a photosensitive layer of a photoreceptor for an image forming apparatus. The formation of the photosensitive layer as an example will be described later in detail.

You may comprise this dip coating apparatus as follows.
You may further provide the raising / lowering mechanism part which moves a to-be-coated body and a coating tank relatively, and immerses and raises a to-be-coated body in a coating liquid. By providing an elevating mechanism, it is possible to automate the dipping of the coated body into the coating liquid and the pulling up from the coating liquid, and it is possible to control the dipping speed and the lifting speed to be constant, and the coating film has a uniform film thickness. Can be formed stably.

The elevating mechanism unit may be one that raises and lowers the object to be applied relative to the application tank (Configuration 1), or may be one that raises and lowers the application tank relative to the object to be applied (Configuration 2).
In the structure 1, since the cloth body is moved up and down by the lifting mechanism unit, the lifting mechanism unit can be downsized. In this case, a plurality of objects to be coated may be held at a time by the elevating mechanism unit, but the objects to be coated need to be attached to and detached from the elevating mechanism unit.
In the configuration 2, for example, a plurality of objects to be coated are held in a suspended state, the coating tank is raised, the plurality of objects to be coated are immersed in the coating liquid, and then the coating tank is lowered to each of the objects to be coated. Since it is possible to perform a coating process in which the body is lifted from the coating liquid, it is possible to increase productivity by simultaneously performing coating on a plurality of coated bodies.
Examples of the lifting mechanism include a ball screw mechanism, a cylinder mechanism, a ball screw mechanism, or a link mechanism combined with a cylinder mechanism.

  In the coating liquid supply unit of the dip coating apparatus, any pump may be used as long as it has a capability of supplying a coating liquid that is equal to or larger than the volume of the body to be coated immersed in the coating tank within a predetermined time. Furthermore, as described above, an inexpensive constant output type general-purpose pump can be used, and in particular, a sine pump, a magnet pump, a gear pump, or the like with less pulsation is preferable.

  A maintenance valve is provided in the liquid supply path on the opposite side of the filter from the flow rate adjustment valve, and both valves are closed during maintenance such as filter replacement, so that the coating liquid can be removed from the coating liquid tank and coating tank. You may prevent it from leaking out.

The flow rate adjusting valve may be a handle type manual valve or an electric valve capable of electrically controlling the degree of opening and closing of the flow path.
As the pressure detector, a pressure gauge having a display unit that displays a pressure value is used when a manual valve is used, and a pressure sensor that converts a pressure into an electric signal and outputs it when an electric valve is used.
When using a pressure gauge and a manual valve, there exists an advantage which can produce a coating liquid supply part at low cost. In this case, the pressure gauge and the manual valve are arranged at a position where an operator can operate the manual valve while looking at the pressure value of the pressure gauge.

When using a pressure sensor and an electric valve, the dip coating apparatus may be provided with a control unit that controls the electric valve.
The control unit may be provided with a function that enables fine flow rate adjustment according to every situation during the coating process, and may further be provided with a function of controlling the lifting operation of the lifting mechanism unit.
For example, when the object to be coated is dipped into the coating liquid in the coating tank by the relative movement between the coated object and the coating tank by the elevating mechanism, the amount of overflow of the coating liquid from the coating tank is constant. As described above, the control unit may have a function of temporarily controlling the electric valve so as to temporarily decrease and increase the flow rate of the coating liquid supplied to the coating tank. A function of controlling the elevating mechanism and the electric valve may be provided so that the elevating and lowering operations are synchronized with the operation of the opening degree of the electric valve.

  In this way, the amount of overflow (overflow surface) of the coating liquid from the coating tank can be made constant when the object to be coated is dipped in the coating liquid in the coating tank and pulled up. Even when the volume of the coated body immersed in the coating solution in the coating tank is reduced, the overflow can be prevented and the liquid level of the coating solution can be prevented from dropping. As a result, for example, it is possible to suppress the problem that the film thickness and film quality of the coating film under the coated body are not uniform due to the influence of the vapor of the coating liquid. In particular, when the coating liquid contains a volatile solvent, the above-mentioned problem is remarkable, and thus the flow rate adjustment of the coating liquid by the control unit for making the overflow amount constant is effective.

The control of the electric valve by the control unit is, for example, in the case of lifting the object to be coated, in advance, it is investigated to what extent the electric valve will be opened when it is pulled up, and the overflow will not stop. This can be done by programming to open.
Alternatively, a liquid level detection sensor for detecting the liquid level of the coating liquid may be provided at or near the opening of the coating tank, and the control unit may control the electric valve based on a signal from the liquid level detection sensor. .
In addition, when the fluctuation of the overflow surface is small when the object to be coated is immersed in the coating liquid in the coating tank and there is no effect on the quality of the coating film, the flow rate adjustment of the coating liquid during immersion may be omitted. .

  In addition, when a manual valve is used as the flow rate adjustment valve, for example, at the timing when the object is pulled up from the coating solution in the coating tank, the operator operates the manual valve to temporarily increase the flow rate of the coating solution. Can be adjusted. In this case, for example, the operator operates the manual valve while monitoring so as not to stop the overflow, or by checking the extent to which the overflow will not stop if the manual valve is opened in advance when the manual valve is opened. Can be operated.

The said structure in a dip coating apparatus may be combined and the above dip coating methods can be performed with the dip coating apparatus of the combined structure.
Furthermore, in the dip coating method, it is preferable to carry out as in the following (A) and (B).

(A) The degree of opening of the flow rate adjustment valve or the rotational speed of the pump is initially set so that the flow rate reduction rate due to pressure loss in the liquid supply path is 74% or less.
Here, the pump will be described. The performance of the pump is shown by a performance curve diagram represented by the discharge amount with respect to the discharge pressure for each liquid viscosity and the number of rotations of the pump. The discharge amount decreases as the discharge pressure increases. . The discharge pressure is the pressure on the discharge side of the pump.
As the pressure resistance in the liquid supply path, a pressure resistance due to the weight of the coating liquid in the coating tank, a pressure resistance due to piping, a pressure resistance due to a filter, and the like can be considered, and the total pressure resistance is the discharge pressure. Also, for example, the discharge pressure may change due to changes in pressure resistance due to clogging of the filter, changes in the weight of the coating liquid in the coating tank, pressure changes due to lifting and lowering of the coating tank in the case of the coating tank lifting method, changes in viscosity of the coating liquid May change.

This change in the discharge pressure is also a change in the discharge amount. When the discharge pressure increases, the discharge amount decreases. This decrease in the discharge amount is called pressure loss, and the discharge amount is not always constant even if the number of rotations of the pump is constant. In addition, since the decrease in the discharge amount is converted into thermal energy, the temperature of the pump and the coating liquid is increased.
Such a change in the temperature of the coating liquid causes a change in the viscosity of the coating liquid and affects the thickness of the coating film and the coating speed, thereby reducing the quality and productivity of the coating film. Further, when the liquid temperature adjusting device for the coating liquid is provided, extra energy is required for the liquid temperature management, so that the economy is poor and the environmental load is increased.
Therefore, in the method (A), application by pressure loss is performed by initially setting the degree of opening of the flow rate adjusting valve or the number of rotations of the pump so that the rate of decrease in flow rate due to pressure loss in the liquid supply passage is 74% or less. The temperature rise of the liquid is suppressed.

(B) The degree of opening of the flow rate adjusting valve so that the flow rate of the coating liquid between the coated body immersed in the coating liquid in the coating tank and the inner surface of the coating tank is 0.6 to 7.2 mm / sec. Alternatively, initialize the pump speed.
When the flow rate is less than 0.6 mm / sec, the coating liquid does not easily overflow from the opening of the coating tank, and streaky coating defects are likely to occur. On the other hand, when the flow rate is higher than 7.2 mm / sec, the coating liquid easily ripples at the opening of the coating tank, and coating defects such as shading unevenness (though there is a difference in film thickness within the specification) are likely to occur.
Therefore, in the method (B), the flow rate is set so that the flow rate of the coating liquid between the coated body immersed in the coating liquid in the coating tank and the inner surface of the coating tank is 0.6 to 7.2 mm / sec. By initially setting the degree of opening of the adjusting valve or the number of rotations of the pump, application defects and uneven application of the coating film formed on the surface of the object to be applied are suppressed.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.

(Embodiment 1)
FIG. 1 is a schematic sectional view showing Embodiment 1 of a dip coating apparatus according to the present invention.
The dip coating apparatus 100 supplies a coating solution L for immersing the object A to be coated and forms a coating film on the surface thereof, and supplies the coating solution L to the coating bath 10 to apply the coating solution 10. The coating solution supply unit 20 that overflows from the coating solution, the coating solution collection unit 30 that collects the overflowing coating solution L, the coating solution recovery unit 30 and the coating solution supply unit 20 are connected to overflow the coating solution recovery unit 30. A circulation path 40 for circulating the liquid L, and an elevating mechanism unit 50 that relatively moves the coated body A and the coating tank 10 to immerse and lift the coated body A in the coating liquid L are provided. .

In FIG. 1, the arrow indicates the flow direction of the coating liquid L, and the symbol L <b> 1 indicates the overflow surface of the coating liquid L.
Further, FIG. 1 shows a case where the lifting mechanism unit 50 holds and lifts one object A, but the lifting mechanism part 50 holds and lifts a plurality of objects A. In view of improving productivity, it is preferable that a plurality of coated objects A be applied simultaneously by one immersion. In this case, the coating tank 10 and the coating liquid recovery unit 30 are formed in a size that allows a predetermined plurality of coated bodies A to be immersed therein.

  The coating liquid supply unit 20 is connected to the circulation path 40 and stores a coating liquid tank 21 that stores the coating liquid L, a liquid supply path 22 that supplies the coating liquid L from the coating liquid tank 21 to the coating tank 10, and a liquid supply path 22, a pump 23 that supplies the coating liquid L from the coating liquid tank 21 to the coating tank 10, a pressure detector 24 that detects a discharge pressure of the pump 23, and a downstream side of the pump 23 in the liquid supply path 22. A filter 25 and a flow rate adjusting valve 26 are provided with a series path portion 27 provided in this order.

<Coating tank>
The coating tank 10 has an upper opening shape and may be of a size that can accommodate the coated body A. Moreover, you may use the application tank which can apply | coat several to-be-coated bodies A simultaneously for the purpose of the improvement of productivity.

<Coating liquid recovery part>
The coating liquid recovery unit 30 includes an L-shaped receiving portion 31 that is liquid-tightly integrated with the upper end portion of the outer peripheral surface of the coating tank 10, and an upper wall portion 32 that is connected to the upper end of the receiving portion 31. The upper wall portion 32 is provided with a hole 32a that allows the coated body A to be taken in and out of the coating tank 10.

<Circulation path>
A coating liquid L outlet is formed in a part of the receiving part 31 of the coating liquid recovery unit 30, and an inlet of the coating liquid L is formed in a part of the upper end portion of the outer peripheral wall 21 a of the coating liquid tank 21. Both ends of the tubular circulation path 40 are connected to the outlet and the inlet. Since the inlet is disposed at a position higher than the outlet, the coating liquid L recovered by the coating liquid recovery unit 30 flows into the coating liquid tank 21 from the inlet through the circulation path 40. Circulate.

<Coating liquid supply unit>
In the coating liquid supply unit 20, the coating liquid tank 21 only needs to have a volume that can accommodate the minimum amount of the coating liquid L necessary for circulation of the coating liquid and the coating liquid L corresponding to the volume of the coated body A. In addition, a lid that can be opened and closed is provided at the top of the coating solution tank so that the coating solution L can be charged and the coating solution L and a solvent in the coating solution can be added. Further, a stirrer for stirring and mixing the coating liquid L in the coating liquid tank 21, a viscometer for measuring the viscosity of the coating liquid L, and the like are provided in the coating liquid tank 21 so that the liquid physical properties of the coating liquid L can be adjusted. It is preferable to do.

Both ends of the tubular liquid supply path 22 are connected to an outlet formed on the bottom wall of the coating liquid tank 21 and an inlet formed on the bottom wall of the coating tank 10.
As the pump 23, a sine pump, a magnet pump, a gear pump, or the like is used, and is disposed on the upstream side of the liquid supply path 22.
A pressure detector 24 is disposed downstream of the pump 23 in the liquid supply path 22. As the pressure detector 24, an analog type or digital type pressure gauge having a display unit for displaying a hydraulic pressure value in the liquid supply path 22 is used.

  A filter 25 is disposed downstream of the pressure detector 24 in the liquid supply path 22. More specifically, the filter 25 is housed in a filter housing section provided in a part of the liquid supply path 22 in an exchangeable manner.

The filter 25 used for the circulation filtration may be a filter having a pore diameter capable of filtering unnecessary materials that become application defects such as foreign matter defects. Moreover, it is necessary to use the thing of the effective filtration area which can obtain the required circulation flow volume in consideration of the pressure resistance by a filter. However, in the case of a filter having a large size, the loss of the coating solution when replacing the filter also increases. For this reason, it is preferable to use a filter having a small size with a small loss of coating liquid when replacing the filter so that the replacement frequency is low.
Furthermore, the filter 25 is required to have pressure resistance because it receives pressure from the coating liquid L sent from the pump 23. The pressure resistance performance of the filter is determined by a specification called the maximum allowable differential pressure, which is the difference between the pressure applied to the upstream side of the filter and the pressure applied to the downstream side.

  A flow rate adjustment valve 26 is disposed downstream of the filter 25 in the liquid supply path 22. As the flow rate adjusting valve 26, a manual valve 26 having a handle 26a that can adjust the degree of opening of the flow path by the operator is used.

<Elevating mechanism part>
The elevating mechanism unit 50 is a ball screw mechanism including a movable unit 51 that holds one end of the workpiece A and a drive unit 52 that elevates and lowers the movable unit 51.
The drive unit 52 has a screw shaft 52a, a guide shaft 52b, a lower connection portion 52c that rotatably holds the lower end of the screw shaft 52a and is connected to the lower end of the guide shaft 52b, and an upper end of the screw shaft 52a that is rotatable. The upper connection part 52d which hold | maintains and connects with the upper end of the guide shaft 52b, and hold | maintains these in parallel, and the motor 52e attached to the upper connection part 52d and rotating the screw shaft 52a are provided.

The movable portion 51 is connected to an elevating plate 51a having a screw hole screwed into the screw shaft 52a and a guide hole through which the guide shaft 52b is inserted, and a lower surface on the distal end side of the elevating plate 51a, and the upper end of the object A to be coated is provided. Holding part 51b to hold.
In addition, the holding | maintenance part 51b will not be specifically limited if the upper end of the to-be-coated body A can be hold | maintained. For example, a protrusion is provided on the upper end surface of the object to be coated A, and a chuck claw mechanism that detachably grips the protrusion of the object to be coated A is provided in the holding part 51b. Or a loop part is provided in the upper end surface of to-be-coated body A, and the hook part which can be engaged / disengaged with the loop part of to-be-coated body A is provided in the holding | maintenance part 51b.

  In the elevating mechanism 50 configured as described above, the elevating plate 51a is horizontally attached to the screw shaft 52a and the guide shaft 52b, and the coated body A is detachably attached to the holding portion 51b in a vertical manner. When the screw shaft 52a rotates in the forward and reverse directions at 52e, the workpiece A is lifted and lowered together with the lifting plate 51a. In addition, you may enable it to adjust the raising / lowering speed of the raising / lowering board 51a by using a servomotor as the motor 52e.

<Coating body and coating liquid>
In the first embodiment, a case where a cylindrical metal body for a photosensitive drum provided in an image forming apparatus is used as the coated body A and a material liquid for forming a photosensitive layer is used as the coating liquid L will be described.
In the manufacture of an electrophotographic photosensitive member, a conductive cylindrical substrate is generally used as the coated body A. In addition, the coating liquid L, which will be described in detail later, has many liquid properties that are optimized depending on the film thickness, coating properties, etc. required for each coating film in many cases because coating liquids with different functions are often applied repeatedly. ing.

[Description of Photosensitive Drum]
FIG. 2 is a longitudinal sectional view showing an electrophotographic photosensitive drum applicable to the present invention.
The photosensitive drum includes a photosensitive drum body 3 including a cylindrical conductive support base 1 as an object to be coated, and a laminated film 2 including a photosensitive layer formed on the outer peripheral surface of the support base 1, and a photosensitive drum main body. 3 and a pair of flanges 4 that cover the openings at both ends. Hereinafter, the “conductive support substrate” may be abbreviated as “support substrate”.

FIG. 3 is a partial cross-sectional view showing various photosensitive drums applicable to the present invention.
The photosensitive drum shown in FIG. 3 has an undercoat layer 5, a charge generation layer 6 a containing a charge generation material, and a charge transport layer 6 b containing a material for transporting the generated charge on the outer peripheral surface of the conductive support substrate 1. And a photosensitive layer 6 laminated in this order. Such a laminated photosensitive drum is widely used. Further, a surface protective layer (not shown) may be provided on the photosensitive layer 6 of the photosensitive drum for the purpose of improving printing durability.

[Conductive support substrate (element tube)]
As a material for the conductive support substrate (object to be coated) 1, metals such as aluminum, copper, nickel, stainless steel, and brass are used, and these metal materials are processed into a cylindrical shape or a cylindrical shape to form a support substrate. It is manufactured. The surface of the support substrate 1 is roughened by machining or chemical surface treatment for the purpose of preventing interference fringes caused by interference of laser light in the photosensitive layer. The point average roughness Rz is 0.5 or more and 2.0 or less.

[Undercoat layer (intermediate layer)]
The undercoat layer 5 is provided on the support substrate 1 as a base layer on the support substrate 1 for the purpose of, for example, covering the surface of the blank tube and covering the unevenness, and preventing deterioration of the chargeability in the photosensitive layer into which charge has been injected. .
Examples of the material for the undercoat layer 5 include polymer materials such as polyamide, copolymer nylon, polyvinyl alcohol, polyurethane, polyester, epoxy, phenol resin, casein, cellulose, and gelatin. Particularly, alcohol-soluble copolymer nylon is used. desirable.
Further, for the purpose of adjusting the volume resistivity of the undercoat layer 5 and improving the repeated aging characteristics in a low temperature and low humidity environment, the undercoat layer 5 includes zinc oxide, titanium oxide, tin oxide, indium oxide and silica. Inorganic pigments such as antimony oxide may be included. In this case, it is preferable to disperse and contain the inorganic pigment in the polymer material so that the weight ratio of the inorganic pigment to the polymer material is about 60/40 to 95/5.

The undercoat layer 5 is prepared by dissolving the polymer material of the undercoat layer 5 in water and a solvent to prepare a material solution for forming an undercoat layer, and optionally mixing and dispersing the inorganic pigment in the material solution, It is formed by applying a material liquid to the surface of the support substrate 1. The thickness of the undercoat layer 5 is preferably about 0.3 to 5.0 μm.
Examples of the solvent used in the material liquid include lower alcohols such as methanol, ethanol, and butanol, mixed solvents of chlorinated solvents such as dichloroethane, chloroform, trichloroethane, trichloroethylene, and perchloroethylene and alcohol solvents.

(Charge generation layer)
The charge generation layer 6a is mainly composed of a charge generation material that generates charges by light irradiation, and includes binder resins, additives such as known binders, plasticizers, and sensitizers used as necessary.
Examples of charge generating materials include perylene imides and perylene acid anhydrides, polycyclic quinone pigments such as quinacridone and anthraquinone, phthalocyanine pigments such as metal phthalocyanines, metal-free phthalocyanines, and halogenated metal-free phthalocyanines, and squalium dyes. Skeletons such as azulenium dye, thiapyrylium dye, carbazole skeleton, styryl stilbene skeleton, triphenylamine skeleton, dibenzothiophene skeleton, oxadiazole skeleton, fluorenone skeleton, bis stilbene skeleton, distyryl oxadiazole skeleton, distyryl carbazole skeleton Azo pigments, bisazo pigments containing a fluorene ring and a fluorenone ring, bisazo pigments containing an aromatic amine, and trisazo pigments.

Examples of the binder resin of the charge generation material include melamine resin, epoxy resin, silicone resin, polyurethane, phenoxy resin, acrylic resin, vinyl chloride-vinyl acetate copolymer resin, polycarbonate, polyvinyl butyral, polyarylate, polyamide, polyester, and the like. . These resins can be used alone or in combination of two or more.
Examples of the organic solvent for the binder resin for the charge generation material include ketones such as acetone, methyl ethyl ketone, cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran and dioxane, and aromatics such as benzene, toluene and xylene. And aprotic polar solvents such as group hydrocarbons, N, N-dimethylformamide, and dimethyl sulfoxide. These organic solvents can be used alone or in combination of two or more.

The material liquid for forming the charge generation layer is prepared by dissolving and dispersing the charge generation material, the binder resin, and, if necessary, an additive in an organic solvent. 30 to 90% by weight is preferable.
The charge generation layer 6a is formed by applying this material solution to the surface of the undercoat layer 5, and the film thickness is preferably about 0.1 to 5 μm.

(Charge transport layer)
The charge transport layer 6b is mainly composed of a charge transport material capable of transporting the charge generated in the charge generation layer 6a, and includes a binder resin, an antioxidant, a plasticizer, a sensitizer, and a lubricant that are used as necessary. Etc. as additives.
Examples of charge transport materials include poly-N-vinyl carbazole and derivatives thereof, poly-γ-carbazolyl ethyl gourmet and derivatives thereof, bilene-formaldehyde condensates and derivatives thereof, polyvinyl bilene, polyvinyl phenanthrene, oxazole derivatives, oxodi Azole derivatives, imidazole derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylvirazoline, phenylhydrazones, hydrazone derivatives, 3-methyl-2 -Electron donating substances such as azine compounds having a benzothiazoline ring, or fluorenone derivatives, dibenzothiophene derivatives, intenothiophene derivatives, phenanthrenequinone derivatives, intenopyridine derivatives, Examples include electron demanding substances such as sandton derivatives, benzo [C] cinnoline derivatives, phenazine oxide derivatives, tetracyanoethylene, tetracyanoquinodimethane, promanyl, chloranil, and benzoquinone.

  Binder resins for charge transport materials include polycarbonate, polyarylate, polyvinyl butyral, polyamide, polyester, polyketone, polyvinyl ketone, polystyrene, polyacrylamide, polysulfone, and other thermoplastic resins, epoxy resins, polyurethane, phenol resins, phenoxy resins, etc. These thermosetting resins can be mentioned. These resins can be used alone or in combination of two or more.

  Organic solvents for binder resins for charge transport materials include alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, and aromatic hydrocarbons such as benzene, toluene and xylene Halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone, cyclohexanone, ethyl acetate And esters such as methyl acetate, and solvents such as dimethylformamide and dimethyl sulfoxide. These organic solvents can be used alone or in combination of two or more.

The material liquid for forming a charge transport layer is prepared by dissolving and dispersing a charge transport material, a binder resin, and, if necessary, an additive in an organic solvent. At this time, the ratio of the charge transport material is the entire material liquid. Is preferably about 3 to 15% by weight.
The charge transport layer 6b is formed by applying this material solution to the surface of the charge generation layer 6a, and the film thickness is preferably about 5 to 50 μm.

[Surface protective layer]
The surface protective layer has a function of improving the durability of the photosensitive layer 6, includes a binder resin as a main component, a charge transport material for improving the responsiveness of the photoreceptor, and a filler for improving wear resistance. May be included.
As the binder resin for the surface protective layer, one or more of the same binder resins as those contained in the charge generation layer 6a can be used.
As the charge transport material for the surface protective layer, one or more of the same charge transport materials as those contained in the charge transport layer 6b can be used.
As the organic solvent for the binder resin of the surface protective layer, one or more of the same solvents as those used for the material liquid for forming the charge generation layer can be used.

  As the filler for the surface protective layer, organic filler such as fluororesin powder such as polytetrafluoroethylene, silicone resin powder and amorphous carbon powder; metal powder such as copper, tin, aluminum and indium; silicon dioxide (silica), aluminum oxide Metal oxides such as (alumina), tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, tin-doped indium oxide; alkali metal of titanate such as potassium titanate Examples thereof include inorganic fillers such as salts. Among these, an inorganic filler is preferable from the viewpoint of wear resistance.

Since the inorganic filler has a suitable hardness, particularly excellent wear resistance can be imparted by adding the inorganic filler to the surface protective layer. Among the inorganic fillers, metal oxides are preferable, and silicon oxide, aluminum oxide, and titanium oxide are particularly preferable.
The filler content in the surface protective layer is preferably 5 to 50% by weight, particularly preferably 10 to 30% by weight of the total solids constituting the surface protective layer.
The thickness of the surface protective layer is not particularly limited, but is preferably about 0.1 to 10 μm.

<Description of immersion coating operation by immersion coating device>
As shown in FIG. 1, the dip coating apparatus 100 is driven in a predetermined state by a pump 23 that rotates at a constant rotational speed so that the coating liquid L passes from the coating liquid tank 21 through the liquid supply path 22 into the coating tank 10. It is continuously supplied at a flow rate. Accordingly, the coating liquid L overflows from the inside of the coating tank 10 and is collected by the coating liquid collection unit 30, and the coating liquid L is returned from the coating liquid collection unit 30 through the circulation path 40 into the coating liquid tank 21. As described above, the coating liquid L circulates in the circulation path of the dip coating apparatus 100.

Prior to this coating liquid circulation, initial setting of the manual valve (flow rate adjusting valve) 26 and the pump 23 is performed.
In the initial setting, the degree of opening of the manual valve 26 and the pump are set so that the control pressure value is equal to or greater than the maximum pressure value of the discharge pressure change that occurs when the pump is maintained at a predetermined number of rotations and the manual valve 26 is fully opened. Is set.
With this initial setting, in the coating process until the filter 25 is replaced, the coating liquid L is supplied to the coating tank 10 at a predetermined flow rate.

On the other hand, by attaching the upper end of the object to be coated A to the holding part 51b at the ascending standby position of the elevating mechanism part 50, the object A is set on the elevating mechanism part 50, and the motor 52e is driven to connect the screw shaft 52a. By rotating in one direction, the elevating plate 51a is lowered, the lower end of the coated body A is passed through the hole 32a of the coating liquid recovery unit 30, and the entire coated body A is immersed in the coating liquid L in the coating tank 10. . At this time, the entire conductive support substrate 9 (see FIG. 2) as the coated body A may be immersed in the coating liquid L.
When the entire body A to be coated is immersed in the coating liquid L, the elevating mechanism unit 50 switches the screw shaft 52a from the descending operation to the ascending operation and pulls up the body A to be coated from the coating liquid L. In addition, it is preferable that the immersion speed and pulling-up speed of the to-be-coated body A by the elevating mechanism 50 are constant.

When the coated body A rises to the ascending standby position, the motor 52e stops, the coated body A coated with the coating liquid is removed from the holding portion 51b, and dried and / or heat-treated to form a coating film. To be coated A is set on the holding portion 51b. Thereafter, the coating liquid L is applied to the surface of the coated body A in the same manner as described above to form a coating film.
In this way, while continuing dip coating on the plurality of coated objects A, the operator monitors the discharge pressure value indicated by the pressure detector 24.

When the circulation of the coating liquid L is continued, foreign matters in the coating liquid L are removed by the filter 25, so that the clogging of the filter 25 gradually proceeds. However, the coating liquid L is predetermined to a certain degree of clogging. It is supplied to the coating tank 10 at a flow rate. The discharge pressure value indicated by the pressure detector 24 at this time is a management pressure value.
When the clogging of the filter 25 exceeds a certain limit, the flow rate of the coating liquid L starts to fall below a predetermined flow rate, and at the same time, the discharge pressure starts to exceed the management pressure value. By recognizing that the discharge pressure has started to exceed the control pressure value, the operator can know that the flow rate of the coating liquid L has started to drop below the predetermined flow rate and that the filter replacement time has come.

Therefore, in such a situation, the operator stops the pump 23 and interrupts the operation of immersing the article A to be applied in the application tank 10 to perform the replacement operation of the filter 25.
When replacing the filter, the manual valve 26 is completely closed, and a maintenance valve (not shown) provided in the liquid supply path 22 opposite to the manual valve 26 is closed with respect to the filter 25 so that a desired flow rate cannot be obtained. Replace the old filter 35 with a new filter.
And after filter replacement | exchange, the initial setting of the manual valve 26 and the pump 23 is performed again, and the immersion application to the to-be-coated body A is restarted. If the rotational speed of the pump 23 is fixed at the initial initial setting, the initial setting of the pump 23 is not necessary.

By the way, in the coating process, when the coated body A immersed in the coating liquid L in the coating tank 10 is pulled up, the volume decreasing rate of the coated body A in the portion immersed in the coating liquid L and the coating liquid L Depending on the flow rate, the overflow of the coating liquid L may stop. In this case, it is preferable that the operator operates the manual valve 26 so as to temporarily increase the flow rate of the coating liquid at the timing of lifting the coated body A from the coating liquid L in the coating tank 10.
Thereby, the malfunction that the film thickness and film quality of the coating film of the lower part of a to-be-coated body become non-uniform | heterogenous under the influence of the vapor | steam of a coating liquid can be suppressed. In particular, when the volatile solvent is contained in the coating solution, the above-mentioned problem is remarkable, and thus the flow rate adjustment of the coating solution with a constant overflow amount is effective.

When the photosensitive drum is manufactured, the conductive support base 1 described with reference to FIG. 2 is used as the coated body A, and the undercoat layer 5, the charge generation layer 6 a described with reference to FIG. The photosensitive layer 6 is formed by sequentially forming the layer 6b and optionally the surface protective layer.
In forming the undercoat layer 5, the undercoat layer forming material liquid is used as the coating liquid L, and the undercoat layer forming material liquid is dip-coated on the outer peripheral surface of the support base 1 as described above, followed by drying and / or drying. The undercoat layer 5 is formed by heat treatment.
The charge generation layer 6a, the charge transport layer 6b, and the surface protective layer are also formed in the same manner as the undercoat layer 5 using the material liquid for forming each layer.

(Embodiment 2)
FIG. 4 is a schematic sectional view showing Embodiment 2 of the dip coating apparatus according to the present invention. In FIG. 4, elements similar to those in FIG. 1 are denoted by the same reference numerals.
The dip coating apparatus 200 of the second embodiment shown in FIG. 4 is different from the dip coating apparatus 100 of the first embodiment shown in FIG. 1 in that the pressure detector 24 in the coating liquid supply unit 220 is a pressure sensor, The flow rate adjustment valve 226 is an electric valve 226, and further includes a control unit 228 having a function of controlling the electric valve 226 to adjust the flow rate of the coating liquid L supplied to the coating tank 10 to a predetermined flow rate. Other configurations are substantially the same as those in the first embodiment.
Also in the case of the second embodiment, as in the first embodiment, after the electric valve 226 and the pump 23 are initially set, the coating liquid L is circulated and the coated body A is dip-coated to form a coating film. A process is performed.

  In this dip coating apparatus 200, the coating body A is applied to the coating body A by the relative movement of the body A to be coated and the coating tank 10 (in this case, movement of the body A to be coated) by the elevating mechanism 50. The controller 228 temporarily increases the flow rate of the coating liquid L to be supplied to the coating tank 10 so that the overflow amount of the coating liquid L from the coating tank 10 becomes constant when it is pulled up after being immersed in L. A function of controlling the electric valve 226 is provided.

  When the coated body A immersed in the coating liquid L is pulled up, when the flow rate of the coating liquid L flowing into the coating tank 10 is smaller than the volume reduction amount of the coated body A in the coating liquid L, the coating liquid L Overflow from the coating tank 10 and the liquid level of the coating liquid L in the coating tank 10 descends. As a result, the solvent vapor of the coating liquid L accumulates in the coating tank 10 and is more susceptible to the solvent vapor toward the lower end side of the surface of the coated body A at the time of pulling up. The film thickness of the coating film may become uneven on the side.

According to the dip coating apparatus 200, when the volume reduction amount of the coated body A in the coating liquid L is smaller, the control unit 228 enters the coating tank 10 so that the overflow from the coating tank 10 of the coating liquid L does not stop. The degree of opening of the electric valve 226 can be controlled to be temporarily increased so as to temporarily increase the flow rate of the coating liquid L to be supplied, thereby forming a coating film uniformly on the surface of the coated body A. Can do.
In the case of the second embodiment, the control of the electric valve 226 by the control unit 228 is carried out by checking in advance to what extent the electric valve 226 is opened at the time of pulling up, before the overflow stops. The electric valve 226 is programmed to open to that extent at the timing.

Here, instead of controlling the electric valve 226 to be temporarily opened largely by the control unit 228, the lifting speed of the coated body A by the elevating mechanism unit 50 is controlled to be slow so as not to stop the overflow of the coating liquid L. It is possible. However, since the film thickness of the coating film formed on the surface of the coated body A is related to the lifting speed of the coated body A from the coating liquid L, it is not preferable to change the lifting speed.
Further, the flow rate adjustment by the electric valve 226 controlled by the control unit 228 may be performed from the start to the completion of the application A to be lifted, but from the start of the lowering of the application A by the elevating mechanism 50. It may be performed until the completion of the ascent. After completion of the pulling up, the control unit 228 controls the electric valve 226 so that the coating liquid L is again supplied into the coating tank 10 at a predetermined flow rate.

(Embodiment 3)
FIG. 5 is a schematic sectional view showing Embodiment 3 of the dip coating apparatus according to the present invention. In FIG. 5, elements similar to those in FIG. 1 are denoted by the same reference numerals.
The dip coating apparatus 300 of the third embodiment shown in FIG. 5 is different from the dip coating apparatus 100 of the first embodiment shown in FIG. 1 in that the coating tank 10 is moved up and down by the lifting mechanism 350. The configuration is substantially the same as that of the first embodiment.
In the case of the third embodiment, as in the first embodiment, after the initial setting of the manual valve 26 and the pump 23 is performed, the coating liquid L is circulated and the coated body A is dip-coated to form a coating film. A process is performed.

In the dip coating apparatus 300 according to the third embodiment, the elevating mechanism unit 350 has a screw shaft 351 erected in the vertical direction, a motor 352 that rotates the screw shaft 351, and a screw hole that is screwed into the screw shaft 351. A lifting plate 353 fixed to the outer peripheral surface of the tank 10, a wire 354 having one end connected to an attachment piece fixed to the outer peripheral surface of the coating tank 10 on the opposite side of the lifting plate 353, and a load reduction to the motor 352 Therefore, a balance weight 355 connected to the other end of the wire 354 and a pulley 356 on which the wire 354 is hung so as to suspend the balance weight 355 are provided.
The weight of the balance weight 355 is substantially equal to the weight of the coating tank 10 filled with the coating liquid L.

  In the case of the dip coating apparatus 300, in the coating liquid supply unit 320, the liquid supply path 322 between the flow rate adjusting valve 26 and the coating tank 10 is made of a flexible material, and the coating tank 10 The circulation path 340 between the coating liquid tank 21 is made of a flexible material. The liquid supply path 322 and the circulation path 340 having flexibility are made of, for example, pipes made of solvent-resistant rubber or soft plastic.

In the case of the third embodiment, for example, a plurality of objects to be applied A are sequentially moved to the application tank 10 while being suspended by the moving means 70 using a chain or a wire.
5 shows a case where the moving means 70 moves the objects A to be applied to the position of the application tank 10 one by one, but moves the objects A to be applied to the position of the application tank 10 a plurality of times. From the viewpoint of improving productivity, it is preferable that a plurality of objects to be coated A are applied simultaneously by one immersion. In this case, the coating tank 10 and the coating liquid recovery unit 30 are formed in a size that allows a predetermined plurality of coated bodies A to be immersed therein.

Then, the application tank 10 is raised by the elevating mechanism 350 and the object A is immersed in the coating liquid L in the application tank 10, and the application tank 10 is lowered by the elevating mechanism 350 to apply the application A to the application liquid. By pulling up from L, dip coating can be performed sequentially on the plurality of coated bodies A. At this time, since the liquid supply path 322 and the circulation path 340 on the application tank 10 side have flexibility, they follow the raising / lowering operation of the application tank 10.
The object A to which the coating liquid L is applied is transported to the transport downstream side of the dip coating apparatus 300 by the moving means 40, and dried and / or heat-treated to form a coating film.

(Other embodiments)
1. In the third embodiment (FIG. 5), the controller 228 controls the electric valve based on the pressure detection signal from the pressure sensor, like the coating liquid supplier 220 in the second embodiment (FIG. 4). The flow rate of the coating liquid L to the coating tank 10 may be adjusted to a predetermined flow rate.
2. The elevating mechanism unit may be omitted from the dip coating apparatus, and the object to be coated may be manually dipped in the coating solution in the coating tank and pulled up.

Example 1
Using the dip coating apparatus described in Embodiment 1 (FIG. 1), an undercoat layer, which is a constituent layer of the photosensitive layer, was formed on the surface of the coated body A as a step of manufacturing the electrophotographic photoreceptor. However, as the coating tank 10, a coating tank having an inner diameter of 65 mm that can immerse 40 coated bodies A at a time was used.
As the coated body A, an aluminum cylindrical tube (conductive support base) having an outer diameter of 30 mm and a length of 357 mm is used, and an undercoat layer is formed on the outer peripheral surface of the coated body A in the manner described in the first embodiment. Formed. The used coating liquid and coating method are as follows.

<Coating solution>
10 parts by weight of titanium oxide (TTO55A: manufactured by Ishihara Sangyo Co., Ltd.) and 10 parts by weight of copolymer nylon (CM8000: manufactured by Toray Industries, Inc.) are added to a mixed solvent of 150 parts by weight of methanol and 100 parts by weight of 1,3-dioxolane, and paint By applying a dispersion treatment for 8 hours with a shaker, 100 kg of a coating solution for forming an undercoat layer was prepared.

<Application method>
This coating liquid was put into the coating liquid tank 21 of the dip coating apparatus 100 shown in FIG. 1 and circulated and filtered. As the pump, a sine pump with a discharge rate of 0.12 L / rotation (Primics Co., Ltd., sine pump MR-120) is used, and the filter 25 has a nominal pore diameter of 20 μm and an effective filtration area of 400 square cm (Advantech Toyo Co. A stainless steel mesh cartridge filter TMC-20-STCH) was used.

As an initial setting, the pump rotation speed is kept constant at 360 rpm so that a flow rate of 10 to 15 liters per minute can be obtained, and the discharge pressure is set to 0.3 MPs in consideration of clogging of the filter 25. The degree of opening of the manual valve 26 was adjusted.
The flow rate of the coating liquid L is a value measured by collecting the coating liquid L overflowed from the coating tank 10.
After the initial setting, the coating liquid L was circulated, and using the elevating mechanism 50, the coated body A was dipped in the coating liquid L filled in the coating tank 10, pulled up, and applied to the coated body A. The coating solution was naturally dried to form an undercoat layer having a thickness of 1.0 μm. At this time, the immersion speed and pulling speed of the coated body A were both set to 3.0 mm / sec.
The formation of such an undercoat layer on the coated body A was performed for 20,000 pieces in 5 days.

(Comparative Example 1)
An undercoat layer was formed in the same manner as in Example 1 except that the circulation flow rate was controlled by adjusting the number of revolutions of the pump.
(Comparative Example 2)
An undercoat layer was formed in the same manner as in Example 1 except that the circulating flow rate was controlled by replacing the clogged filter 25 with a new and washed filter.

<Result>
The discharge pressures of Example 1 and Comparative Examples 1 and 2 in the initial stage between 1 to 200 dip-coated objects A and the final stage of 19800 to 20000 dip-coated objects A, Table 1 shows the number of revolutions of the pump and the flow rate of the coating liquid.
Further, the flow rate reduction rate due to pressure loss in Example 1 and Comparative Examples 1 and 2, the flow rate in the coating tank during coating, the number of pump adjustments, the number of filter replacements, the continuous productivity, the temperature rise of the coating solution, coating defects, and coating unevenness Are also shown in Table 1.

The flow rate reduction rate due to pressure loss was determined by the following formula (1) based on the numerical values shown in Table 1.
Formula (1): 100- (a / (b * c)) * 100
a: Flow rate of coating liquid b: Pump discharge amount c: Pump rotation speed

The flow rate in the coating tank during coating is the flow rate of the coating liquid between the coated body and the inner surface of the coating tank, and was determined by the following equation (2).
Formula (2): (d−e) ÷ (f−g)
d: Flow rate of the coating liquid e: Volume decrease of the coated body in the coating liquid f: Area of the coating tank opening g: Cross-sectional area of the coated body

The temperature of the coating solution was increased by measuring the temperature of the coating solution in the coating solution tank.
Evaluation of coating defects and coating unevenness was made by visually observing the undercoat layer after drying, and ◯ when it was not present, Δ when it was within the quality limit, and × when it was beyond the quality limit.

The evaluation of continuous productivity was based on the following evaluation criteria.
〔Evaluation criteria〕
○: There was no production interruption for the circulation flow rate control and no consumption of coating liquid other than coating.
Δ: It was necessary to temporarily interrupt production (about 30 minutes) for circulation flow rate control.
X: Production was required to be interrupted temporarily (about 30 minutes) for circulation flow rate control, and the coating solution was consumed except for coating.

In Example 1, the circulation flow rate could be maintained at 15 L / min from the initial stage to the end stage. Further, the continuous productivity was good (◯), and there was no temperature rise of the coating solution, no coating defects, and coating unevenness.
In Comparative Example 1, since the flow rate decrease due to clogging of the filter was adjusted by the number of rotations of the pump in order to keep the circulating flow rate in the range of 10 to 15 L / min, the continuous productivity was slightly poor (Δ). There was no temperature rise of the coating solution, coating defects, and coating unevenness.
In Comparative Example 2, since the dip coating was interrupted and the filter was replaced when the flow rate became insufficient due to filter clogging, the coating solution lost due to the filter replacement occurred, and the continuous productivity was poor (x). However, there was no temperature rise of the coating solution, coating defects, and coating unevenness.

(Example 2)
The same procedure as in Example 1 was performed except that the pump speed was changed to 340 rpm and the discharge pressure was controlled so that the flow rate of the coating liquid was 12 liters per minute.
(Example 3)
The same procedure as in Example 1 was performed except that the pump rotation speed was changed to 380 rpm and the discharge pressure was controlled at 0.4 MPs so that the flow rate of the coating liquid was 12 liters per minute.
(Example 4)
The same procedure as in Example 1 was performed except that the pump rotation speed was changed to 410 rpm and the discharge pressure was controlled at 0.5 MPs so that the flow rate of the coating liquid was 12 liters per minute.

(Example 5)
The same procedure as in Example 1 was performed except that the pump rotation speed was changed to 440 rpm and the discharge pressure was controlled at 0.6 MPs so that the flow rate of the coating liquid was 12 liters per minute.
(Example 6)
The same procedure as in Example 1 was performed except that the pump rotation speed was changed to 302 rotations per minute and the discharge pressure was controlled so that the flow rate of the coating liquid was 8 liters per minute.
(Example 7)
The same procedure as in Example 1 was performed except that the pump rotation speed was changed to 310 rotations per minute and the discharge pressure was controlled so that the flow rate of the coating liquid was 9 liters per minute.

(Example 8)
Using a sine pump with a discharge rate of 0.22 L / rotation (sign pump MR-125, manufactured by Primex Corporation), changing the pump rotation speed to 395 rotations per minute so that the flow rate of the coating liquid is 50 liters per minute The same operation as in Example 1 was performed except that the discharge pressure was controlled.
Example 9
Using a sine pump with a discharge rate of 0.22 L / revolution (sign pump MR-125, manufactured by Primex Corporation), changing the pump rotation speed to 435 revolutions per minute so that the flow rate of the coating solution is 60 liters per minute The same operation as in Example 1 was performed except that the discharge pressure was controlled.

<Result>
Table 1 shows the results of Examples 2, 3, 4, 5, 6, 7, 8 and 9 for the same items as in Example 1.
In each of Examples 2, 3, 4, 5, 6, 7, 8, and 9, the pump rotation speed adjustment and filter replacement were not necessary, and the continuous productivity was good.
In Examples 2, 3, 8 and 9, the flow rate reduction rate due to pressure loss was 74% or less, and no increase in the temperature of the coating liquid due to the effect of pressure loss was observed.

In Examples 4, 5, 6 and 7, the flow rate drop rate due to the pressure loss was 76% or more, and it was found that the temperature of the coating liquid increased due to the effect of the pressure loss. Therefore, in these cases, it is preferable to provide a liquid temperature adjusting means for suppressing the temperature rise of the coating liquid in the dip coating apparatus. Although the temperature rise of the coating solution depends on the degree, it may affect the viscosity of the coating solution, the film thickness of the coating film, and the coating speed, so that the quality and productivity may decrease.
In Examples 2, 3, 4, 5, 7, and 8, the flow rate of the coating solution in the coating tank during dip coating is in the range of 0.6 to 7.2 mm / sec, and there are no coating defects and coating unevenness. It was.
On the other hand, in Example 6, the flow rate of the coating liquid in the coating tank was smaller than 0.6 mm / sec, and streaky coating defects occurred within the quality limit. Further, in Example 9, the flow rate of the coating solution in the coating tank was larger than 7.2 mm / sec, and slight coating unevenness occurred within the quality limit.

1 Conductive support substrate (Subject to be coated)
DESCRIPTION OF SYMBOLS 2 Laminated | multilayer film 3 Photosensitive drum main body 4 Flange 5 Photosensitive layer 5a Undercoat layer 5b Charge generation layer 5c Charge transport layer 10 Coating tank 20 Coating liquid supply part 21 Coating liquid tank 22 Liquid supply path 23 Pump 24 Pressure detector 25 Filter 26 Flow adjustment valve (manual valve)
27, 227 Series path 30 Coating liquid recovery part 40 Circulation path 50, 350 Lifting mechanism part 226 Flow rate adjusting valve (electric valve)
228 Control unit A Object to be coated L Coating liquid

Claims (11)

A coating tank for storing a coating liquid for immersing the object to be coated and forming a coating film on the surface thereof, a coating liquid supply unit for supplying the coating liquid to the coating tank and causing the coating tank to overflow, and an overflowing coating liquid And a circulation path for circulating the coating liquid overflowed from the coating liquid collecting section by connecting the coating liquid collecting section and the coating liquid collecting section and the coating liquid supply section,
The coating liquid supply unit is connected to the circulation path and stores the coating liquid tank, the supply liquid path for supplying the coating liquid from the coating liquid tank to the coating tank, the supply liquid path provided from the coating liquid tank A series path section in which a pump for supplying the coating liquid to the coating tank, a pressure detector for detecting the discharge pressure of the pump, and a filter and a flow rate adjusting valve are provided in this order on the downstream side of the pressure detector of the liquid supply path A dip coating apparatus comprising:   The dip coating apparatus according to claim 1, wherein the pressure detector is a pressure gauge and the flow rate adjusting valve is a manual valve. While the pressure detector is a pressure sensor, the flow rate adjustment valve is an electric valve,
The dip coating apparatus according to claim 1, further comprising a control unit that controls the electric valve.   The dip coating apparatus according to any one of claims 1 to 3, further comprising an elevating mechanism that moves the coated body and the coating tank relatively to immerse and lift the coated body in the coating solution. Further comprising an elevating mechanism that raises and lowers the object to be applied with respect to the application tank and immerses it in the application liquid and pulls it up;
When the object to be coated is dipped in the coating solution in the coating tank by the relative movement between the coated object and the coating tank by the elevating mechanism, the overflow amount of the coating liquid from the coating tank is constant. The dip coating apparatus according to claim 3, wherein the control unit has a function of controlling the electric valve so as to temporarily increase the flow rate of the coating liquid supplied to the coating tank.   The dip coating apparatus according to any one of claims 1 to 5, wherein the coated body is a cylindrical or columnar metal body, and the coating liquid is a material liquid for forming a photosensitive layer of the photosensitive body. A dip coating method using the dip coating apparatus according to claim 1, wherein the pump is driven to supply the coating liquid from the coating liquid tank to the coating tank, and the object to be coated and the coating tank are relatively moved. And after immersing the object to be coated in the coating solution in the coating tank, the step of pulling up the object to be coated from the coating solution and forming a coating film on the surface of the object to be coated,
Adjust the degree of opening of the flow rate adjustment valve and the rotation speed of the pump so that the control pressure value is equal to or greater than the maximum pressure value of the discharge pressure change that occurs when the pump is maintained at the specified speed and the flow rate adjustment valve is kept fully open. Initial settings,
A dip coating method for managing the flow rate of the coating liquid supplied to the coating tank by managing the pressure value detected by the pressure detector.   When the object to be coated is dipped in the coating solution in the coating tank by the relative movement between the coated object and the coating tank by the elevating mechanism, the overflow amount of the coating liquid from the coating tank is constant. The dip coating method according to claim 7, wherein the flow rate adjusting valve is temporarily adjusted so as to temporarily increase the flow rate of the coating liquid supplied to the coating tank. A dip coating method using the dip coating apparatus according to claim 5, wherein the pump is driven to supply the coating liquid from the coating liquid tank to the coating tank, and the object to be coated and the coating tank are relatively moved. And after immersing the object to be coated in the coating solution in the coating tank, the step of pulling up the object to be coated from the coating solution and forming a coating film on the surface of the object to be coated,
Adjust the degree of opening of the flow rate adjustment valve and the rotation speed of the pump so that the control pressure value is equal to or greater than the maximum pressure value of the discharge pressure change that occurs when the pump is maintained at the specified speed and the flow rate adjustment valve is kept fully open. Initial settings,
By managing the pressure value detected by the pressure sensor, the flow rate of the coating liquid supplied to the coating tank is managed,
When the object to be coated is dipped in the coating solution in the coating tank by the relative movement between the coated object and the coating tank by the elevating mechanism, the overflow amount of the coating liquid from the coating tank is constant. A dip coating method in which the control unit temporarily controls the electric valve so as to temporarily increase the flow rate of the coating liquid supplied to the coating tank.   The dip coating according to any one of claims 7 to 9, wherein the degree of opening of the flow rate adjusting valve or the number of rotations of the pump is initially set so that a flow rate reduction rate due to pressure loss in the liquid supply path is 74% or less. Method.   The degree of opening of the flow rate adjusting valve or the pump is adjusted so that the flow rate of the coating liquid between the coated body immersed in the coating liquid in the coating tank and the inner surface of the coating tank is 0.6 to 7.2 mm / sec. The dip coating method according to any one of claims 7 to 10, wherein the rotational speed is initially set.

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