JPH02207259A - Dip coating device for conductive base body - Google Patents

Abstract

PURPOSE:To maintain a coated amt. constant and to always form a photosensitive layer having a uniform film thickness by occasionally recovering the photosensitive coating liquid in a dipping tank into an auxiliary tank and adjusting the viscosity of the recovered photosensitive coating liquid by a viscosity adjusting means to a prescribed value and then supplying the liquid again into the dipping tank. CONSTITUTION:After a cylindrical conductive base body 1 is dipped into the dipping tank 3 in which the photosensitive coating liquid 2 is housed, the base body is pulled up to apply the photosensitive coating liquid 2 on the conductive base body 1. The photosensitive coating liquid 2 housed in the dipping tank 3 is occasionally recovered into the auxiliary tank 5 and the viscosity of the photosensitive coating liquid 2 recovered in the auxiliary tank 5 is adjusted to a prescribed viscosity by a viscosity adjusting means 10. This liquid is circulated from the auxiliary tank 5 and is again supplied into the dipping tank 3 so that the viscosity of the photosensitive coating liquid 2 supplied into the dipping tank 3 is maintained constant. The coated amt. is kept constant in this way and the film thickness of the photosensitive layer formed on the conductive base body 1 is uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dip coating apparatus for a conductive substrate, which is used when applying a photosensitive coating liquid to a conductive substrate.

[Prior Art and its Problems] In photoreceptors, various organic and inorganic photoconductive materials have conventionally been used as materials constituting a photosensitive layer formed on a conductive substrate.

Here, photoreceptors using organic photoconductive materials as the material constituting the photosensitive layer have some problems in terms of sensitivity, durability, stability against the environment, etc., but such photoreceptors can be manufactured. In some cases, a photosensitive coating liquid is prepared by dissolving or dispersing an organic photoconductive material together with a resin in an organic solvent, and this photosensitive coating liquid is applied onto a conductive substrate and then dried. It is easier to manufacture than photoreceptors using inorganic photoconductive materials, and is attracting attention as a photoreceptor that is superior in terms of manufacturing cost.

In addition, in recent years, in order to solve the problems with photoreceptors using organic photoconductive materials as described above, the charge generation function and charge transport function in the photosensitive layer have been assigned to separate substances, respectively. A functionally separated organic photoreceptor has been developed in which characteristics such as two-spectral sensitivity, charging ability, and durability can be changed arbitrarily by combining arbitrary materials, allowing the selection of characteristics that suit the purpose.

Even in such functionally separated organic photoreceptors, a photosensitive coating liquid for the charge generation layer, in which a charge generation material is dispersed or dissolved in a binder, is generally applied onto a conductive substrate. is dried to form a charge generation layer with a thickness of 0.05 to 1 μm, and a photosensitive coating liquid for a charge transport layer in which a charge transport material is dispersed or dissolved in a binder is applied.
This is dried to form a charge transport layer with a thickness of 5 to 30 μm.

For these organic photoreceptors, methods such as spray coating, roll coating, blade coating, and dip coating are generally used to coat the above-mentioned photosensitive coating liquids on the conductive substrate. It is used.

Among these coating methods, after immersing the conductive substrate in a dipping tank containing each of the above-mentioned photosensitive coating liquids,
When manufacturing these photoreceptors, the dip coating method, in which the conductive substrate is lifted from a dipping tank and a photosensitive coating liquid is applied to the conductive substrate, is superior in terms of productivity and manufacturing cost. It is widely used in

In such a dip coating method, as described above, the conductive substrate is immersed in a dipping bath containing each photosensitive coating liquid and pulled up, and each photosensitive coating liquid is applied onto the conductive substrate. As a result, the photosensitive coating liquid tends to drip vertically on the conductive substrate, resulting in uneven coating or streaks in the photosensitive layer formed on the conductive substrate, and the film of the photosensitive layer in the vertical direction. There was a drawback that the thickness unevenness became large, which adversely affected the image.

In particular, when forming a thin layer with a thickness of 1 μm or less, such as the charge generation layer in the functionally separated photoreceptor, the adverse effects on the image due to uneven coating as described above become a major problem. Ta.

Furthermore, if a low boiling point solvent is used as a solvent for photosensitive coating liquid, the solvent will evaporate from the photosensitive coating liquid stored in the immersion tank, changing the viscosity and concentration of the photosensitive coating liquid. ,
It is very difficult to form a photosensitive layer with a uniform thickness by keeping the amount of photosensitive coating liquid applied to the conductive substrate constant, and it is difficult to form a photosensitive layer with a uniform thickness by applying the photosensitive coating liquid to the conductive substrate one by one as described above. When applying a liquid to mass-produce photoreceptors, there is a problem in that the thickness of the photosensitive layer formed on the conductive substrate gradually changes, impairing the uniformity of the film thickness on the photoreceptor.

[Problems to be Solved by the Invention] The present invention utilizes a dip coating method in which a conductive substrate is immersed in a dipping bath containing a photosensitive coating liquid, and then the conductive substrate is lifted out of the dipping bath. The object of the present invention is to solve the above-mentioned problems when applying a photosensitive coating liquid to a conductive substrate.

That is, in the present invention, after a conductive substrate is immersed in a dipping tank containing a photosensitive coating liquid, the conductive substrate is pulled up from the dipping bath and the photosensitive coating liquid is applied onto the conductive substrate. In some cases, there is less occurrence of uneven coating of the photosensitive coating liquid on the conductive substrate, and thin layers with a thickness of 1 μm or less, such as the charge generation layer in a functionally separated photoreceptor, can be formed well. Furthermore, even when a low boiling point solvent is used as a solvent for the photosensitive coating liquid, it is possible to form a photosensitive layer with a uniform thickness by keeping the amount of the photosensitive coating liquid applied to the conductive substrate constant. An object of the present invention is to provide a dip coating apparatus for a conductive substrate, which is capable of making the film thickness of a photosensitive layer on each photoreceptor constant even during mass production.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention serves as a dip coating device for conductive substrates, and includes a dipping tank containing a photosensitive coating liquid to be applied to the conductive substrates, and a dipping tank containing a photosensitive coating liquid to be applied to the conductive substrates. An auxiliary tank that communicates with the immersion tank and collects and circulates the photosensitive coating liquid contained in the immersion tank, and a viscosity adjusting means that adjusts the viscosity of the photosensitive coating liquid collected in the auxiliary tank. That's what I did.

Here, the viscosity adjusting means for adjusting the viscosity of the photosensitive coating liquid collected in the auxiliary tank supplies an appropriate amount of solvent, etc. to this auxiliary tank while measuring the viscosity of the photosensitive coating liquid in the auxiliary tank. The viscosity of the photosensitive coating liquid in the auxiliary tank may be adjusted. However, while measuring the viscosity of the photosensitive coating liquid in the auxiliary tank, an appropriate amount of the coating liquid may be adjusted based on the measurement results. An automatic control type that automatically controls and supplies the solvent, etc. is convenient.

[Function] In the electroconductive substrate dip coating apparatus configured as described above, the photosensitive coating liquid contained in the dipping tank is appropriately collected in the auxiliary tank, and the recovered photosensitive coating liquid is collected in the auxiliary tank. The viscosity of the coating liquid is adjusted to a predetermined viscosity by the viscosity adjusting means.

The photosensitive coating liquid whose viscosity has been adjusted in this way is then circulated from the auxiliary tank and supplied to the dipping tank again to maintain a constant viscosity of the photosensitive coating liquid stored in the dipping tank. There is.

When a conductive substrate is immersed in a dipping tank in which the viscosity of the photosensitive coating liquid is kept constant in this way and the photosensitive coating liquid is applied, the photosensitive coating liquid applied on the conductive substrate is The coating amount of the coating liquid becomes constant, and the thickness of the photosensitive layer formed on the conductive substrate becomes uniform.

[Example] Hereinafter, an example of the present invention will be specifically described based on the accompanying drawings.

In the electroconductive substrate dip coating apparatus of each example shown in FIGS. 1 and 2, a photoconductive material is applied together with a binder resin as a photosensitive coating liquid (2) to be applied to a conductive substrate (1). The thus prepared photosensitive coating liquid (2), which is dispersed or dissolved in an organic solvent, is housed in a cylindrical dipping tank (3).

Then, after immersing the cylindrical conductive substrate (1) in the dipping tank (3) containing the photosensitive coating liquid (2), the conductive substrate (1) is placed in the dipping tank (3). 3) The photosensitive coating liquid (2) is applied onto the conductive substrate (1) by pulling it up from inside.

Here, an overflow receiver (4) is provided at the upper part of the immersion tank (3) along its outer periphery, and the conductive substrate (1) is immersed in the immersion tank 3) as described above. In case,
Photosensitive coating liquid (2) overflowing from the dipping tank (3)
This overflow receiver is accommodated in part (4).

This overflow receiver is provided with a discharge port (4a) at the bottom of the part (4), and this discharge port (4a) and the auxiliary tank (
5) is connected to the recovery pipe 7〉 equipped with a valve (6) at an appropriate position, and the overflow receiver transfers the photosensitive coating liquid (2) stored in the part (4) to the auxiliary tank (5).
).

In addition, at the bottom of the dipping tank (3), there is a photosensitive coating liquid (2).
Collection port (3a) for collecting the water into the auxiliary tank (5)
and switch the bypass pipe (8) attached to this recovery port (3a) to the recovery pipe (7) with a valve (
9).

The photosensitive coating liquid (2) contained in the dipping tank (3)
When recovering the water into the auxiliary tank (5), the bypass pipe (8) and the recovery pipe (7) are communicated with each other by the switching valve (9), and the recovery port ( 3a) to bypass pipe (8) and recovery pipe 7
), the photosensitive coating liquid (2) is collected into an auxiliary tank (5).

On the other hand, the auxiliary tank (5) that collects the photosensitive coating liquid (2) from the immersion tank (3) is equipped with the auxiliary tank (5) as described above.
) is provided with viscosity adjusting means (10) for adjusting the viscosity of the photosensitive coating liquid (2) introduced into the photosensitive coating liquid (2).

Here, the auxiliary tank 5) is adjusted by the viscosity adjusting means
In order to adjust the viscosity of the photosensitive coating liquid (2) collected in the auxiliary tank (5), in the embodiment shown in FIG. (1
Add this photosensitive coating liquid (2) while stirring uniformly according to 1).
) is measured using a viscometer (12).

As a result of this measurement, if the viscosity of the photosensitive coating liquid (2) recovered in the auxiliary tank (5) has increased, the solvent tank (13) and the auxiliary tank (5) are connected. The solenoid valve (15) provided on the solvent supply pipe (14) is opened, and the photosensitive coating liquid (2) in the auxiliary tank (5) is stirred by the stirring means (11). ) is supplied into the auxiliary tank (5) until the dilution solvent (16) contained in the solvent tank (13) reaches a predetermined viscosity.

The embodiment shown in FIG. 2 is also almost the same as the embodiment shown in FIG. The control section (
12a) is connected to the solenoid valve (
15) so that the opening and closing of this solenoid valve (15) is automatically controlled by the control section (12a) of the viscometer (12), and the photosensitive coating liquid collected in the auxiliary tank (5) is connected to If the viscosity of (2) is increasing, check the viscometer (1).
The control unit (10a) of 2) automatically opens the solenoid valve (15), and the photosensitive coating liquid (2) in the auxiliary tank (5)
The diluent (16) is supplied from the solvent tank (13) to the auxiliary tank (5) until the viscosity reaches a predetermined value.

When the photosensitive coating liquid (2) adjusted to an appropriate viscosity is circulated in the auxiliary tank (5) and returned to the dipping tank (3), the bottom of the auxiliary tank (5) is The supply pipe (17) connected to the circulation port (5a) is passed from the provided circulation port (5a) to the auxiliary tank (
5) The photosensitive coating liquid (2) in the chamber is sucked by a pump (18), and foreign substances in the photosensitive coating liquid (2) are removed by a filter (19) connected to this supply pipe (17). The immersion tank (
3) While adjusting the flow rate of the photosensitive coating liquid (2) supplied into the dipping tank (3), the nozzle (2) provided at the bottom of the dipping tank (3) is adjusted.
1), a photosensitive coating liquid (2) adjusted to an appropriate viscosity is supplied into the dipping tank (3).

In this way, the viscosity of the photosensitive coating liquid (2) in the dipping tank (3) is always kept constant, and the conductive substrate (1) is immersed in this dipping tank (3). When applying the photosensitive coating liquid (2), a certain amount of the photosensitive coating liquid (2) is always applied to the conductive substrate (1), and a uniform photosensitive layer is always formed on the conductive substrate (1). will be done.

In addition, when the work of applying the photosensitive coating liquid (2) to the conductive substrate (1) is interrupted, the switching valve (
9), the recovery pipe (7) and the bypass pipe (8)
The photosensitive coating liquid (2) contained in the dipping tank (3) is passed through the bypass pipe (8) and the recovery pipe (7) from the collection port (3a) at the bottom of the dipping tank (3). is collected in the auxiliary tank (5).

Then, in this way, the photosensitive coating liquid (2) is placed in the auxiliary tank (5).
), the valve (6) provided on the recovery pipe (7) and the supply amount adjustment valve (20) provided on the supply pipe (17) are closed, and the photosensitive coating liquid (2 ) is stored in the auxiliary tank (5) in a sealed state, evaporation of the solvent is suppressed, and the photosensitive coating liquid (
The viscosity change in 2) and the loss of the photosensitive coating liquid (2) are reduced, and deterioration of the working environment is also suppressed.

Although not shown in the above embodiments, in order to stabilize the state of the photosensitive coating liquid (2), temperature adjustment means may be provided in the dipping tank (3) and the auxiliary tank (5). It is preferable to do so.

[Effects of the Invention] As described in detail above, in the dip coating apparatus for conductive substrates according to the present invention, the photosensitive coating liquid contained in the dipping tank is appropriately collected in the auxiliary tank, and the photosensitive coating liquid is collected in the auxiliary tank. The viscosity of the recovered photosensitive coating liquid is adjusted to a predetermined value by a viscosity adjusting means, and the photosensitive coating liquid whose viscosity has been adjusted in this way is circulated and supplied to the auxiliary tank and then to the immersion tank again. As a result, the viscosity of the photosensitive coating liquid contained in the dipping tank is always maintained at a desired viscosity.

As a result, when a conductive substrate is immersed in such a dipping bath and pulled up to apply a photosensitive coating liquid to the conductive substrate, the viscosity of the photosensitive coating liquid contained in the dipping bath is always constant. The coating amount of the photosensitive coating liquid applied to the conductive substrate is maintained at a predetermined value, and a photosensitive layer with a uniform thickness is always formed. Even if the film thickness is as thin as 1 μm or less, such as the charge generation layer in the body, it is now possible to form a film with a constant and uniform thickness, eliminating the negative effects on images caused by uneven coating. Became.

Furthermore, even if the solvent used in the photosensitive coating liquid is a low boiling point solvent, there is no change in the viscosity of the photosensitive coating liquid, and a constant photosensitive layer is always formed, resulting in a photoreceptor with stable performance. can now be mass-produced.

Furthermore, by collecting the photosensitive coating liquid contained in the immersion layer into an auxiliary tank as needed, it is now possible to suppress loss of photosensitive coating liquid due to solvent evaporation and deterioration of the working environment.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a dip coating apparatus according to one embodiment of the invention, and FIG. 2 is a schematic sectional view of a dip coating apparatus according to another embodiment of the invention. (1) Conductive substrate (3) Immersion tank (8) Viscosity adjustment means (2) Photosensitive coating liquid (5) Auxiliary tank

Claims (1)

[Claims] 1. An immersion tank containing a photosensitive coating liquid to be applied to a conductive substrate, an auxiliary tank communicated with this immersion tank to collect and circulate the photosensitive coating liquid contained in the immersion tank, and this auxiliary tank. 1. A dip coating apparatus for a conductive substrate, comprising: viscosity adjusting means for adjusting the viscosity of a photosensitive coating liquid recovered.