JPH01127060A - Coating device - Google Patents

Abstract

PURPOSE:To prevent the inner side of a recess of an object to be coated from being coated with coating liquid, by providing a protruding portion in a coating tank, allowing said protruding portion to be inserted into the recess of said object when said object is immersed in coating material, and controlling the pressure in the recess by means of a pressure control means. CONSTITUTION:An object to be coated 4 having a recess 4c therein is immersed in a coating liquid 1 contained in a coating tank 2 and then pulled up therefrom so that the coating liquid 1 is applied to the object 4, in which a protruding portion 3 is provided inside the bottom wall 2a of the coating tank 2 in such a manner that said portion 3 is inserted into the recess 4c when the object 4 is immersed, while the pressure within the recess 4c is controlled by a pressure control means comprising a piston 38 and a cylinder 39. As a result, application of coating liquid to the inner side of the recess 4c is prevented, resulting in saving coating liquid and in the elimination of troublesome work for removal of coating liquid having been applied, while defective coating due to air leak is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a coating apparatus, for example, a dip coating apparatus for coating and forming a photosensitive layer of an electrophotographic photoreceptor.

BACKGROUND OF THE INVENTION Conventionally, inorganic photoreceptors having a photosensitive layer containing an inorganic photoconductive substance such as selenium, zinc oxide, or cadmira sulfide are widely used as electrophotographic photoreceptors.

On the other hand, the use of various organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors has been actively developed and researched in recent years. For example, in Japanese Patent Publication No. 50-10496,
An organic photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2.4.7-)dinitro-9-fluorenone is described. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability. In order to improve such defects, in the photosensitive layer,
Attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the functions of carrier generation and transport to different substances. In such so-called function-separated type electrophotographic photoreceptors, substances that exhibit each function can be selected from a wide range of materials, so it is relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. Is possible.

When coating and forming the photosensitive layer of such an electrophotographic photoreceptor, it is necessary to form a thin, uniform layer with high precision in order to maintain good sensitivity characteristics and prevent image defects such as density unevenness, thereby exhibiting good performance as a photoreceptor. It is necessary to apply a layer.

Conventionally, various coating methods such as dip coating, spray coating, spinner coating, wire bar coating, blade coating, and roller coating have been known as coating methods for the photosensitive layer of electrophotographic photoreceptors, but dip coating and spray coating are the main methods. Coating is used.

Among these, dip coating is often used to form a uniform coating on a cylindrical object (such as a conductive substrate).

FIG. 13 shows a coating device used for dip coating.

A predetermined coating liquid 1 is contained in the coating tank 2 . During dip coating, the cylindrical conductive substrate C is sometimes referred to as a substrate drum.

) 4 into the coating liquid 1 with the opening 4b facing downward,
Next, hold the handle 5a of the lid 5 and leave it in the base drum, but when the base drum 4 is immersed, the outer circumferential surface 4e of the base drum 4 and the coating tank are mixed with the air filling the hollow part 4c inside the base drum 4. The coating liquid is applied to the outer circumferential surface 4e of the base drum up to a height of 48 of 2, and a uniform coating film is formed.

At this time, the liquid level rises by an amount corresponding to the volume of the immersed portion of the base drum 4 and the volume of air within that portion, that is, by a height l.

Therefore, such a coating device has the following problems.

That is, since the base drum 4 is immersed and moved up and down between the position 1 indicated by the dotted chain line, the coating liquid 1 adheres to the inner circumferential surface 2b of the side wall of the coating tank, and the adhered coating liquid dries. A dry product 9 is produced. It is believed that the dried matter 9 mixes into the coating liquid 1, causing a change in the composition of the coating liquid 1, causing deterioration, and further causing so-called foreign matter defects (coating defects). In addition, if the coating liquid 1 deteriorates, it will be necessary to discard it or replace it, which will lead to increased costs such as raw material costs, and will require cumbersome manual work such as cleaning the container each time it is disposed of or replaced. Become.

As a countermeasure to this problem, Utility Model Application No. 62-591
Japanese Patent No. 75 discloses a coating device that includes a pedestal that can be raised and lowered in a coating tank, an object to be coated is placed on the upper end of the pedestal, and the object to be coated is immersed and pulled up by raising and lowering the pedestal. In this method, a hole is provided in the bottom of the coating tank, the pedestal is fitted into the hole, and the pedestal is moved up and down by a drive device located outside the coating tank. However, in such coating devices, the coating liquid tends to leak from the gap between the coating tank and the pedestal (a separate sealing member is required, which complicates the device, and the coating liquid tends to leak especially when the pedestal is raised and lowered. It is also considered necessary to prevent the coating liquid from adhering and drying.

As a method for preventing such defects, a so-called overflow one-type method is known, and FIG. 14 shows a schematic cross-sectional view of a dip coating device using this method.

A predetermined coating liquid 1 is stored in the coating tank 2, and a tray 6 is provided around the side wall 2d of the coating tank 2, and the liquid is supplied into the coating tank 2 from a supply port 11 as shown by arrow E. Further, the liquid overflows over the upper edge 2e of the side wall 2d in the circumferential direction of the coating tank 2, is collected by the tray 6, and is discharged from the discharge port 8 into the tank 12. The cylindrical conductive substrate 4 is immersed in the coating liquid 1 as shown by the dashed line, and then the conductive substrate 4 is pulled up at a predetermined speed 5 as shown by the arrow to perform dip coating. During this dip coating, since the coating liquid 1 continues to overflow over the upper edge 2e of the side wall 2d as described above, the level of the coating liquid 1 is kept constant.

According to such an overflow one-type coating method, since the liquid level is kept constant in the coating device, there is no formation of dry solids on the inner wall of the coating tank, and even if they are formed, they can be filtered by the filter 14, so foreign substances can be removed. Effective in preventing coating defects due to adhesion.

However, overflow type coating equipment has the disadvantage of requiring a large amount of coating liquid for the coating tank and circulation system (for example, the amount of coating liquid required is several times that of the coating apparatus shown in Fig. 13). ). Therefore, the cost of raw materials is high, and when the coating liquid reaches its usage limit, a large amount of the coating liquid must be discarded or replaced, which is disadvantageous in terms of cost and the like.

C0 Purpose of the Invention The purpose of the present invention is to prevent coating defects due to foreign matter adhesion (foreign matter defects).
It is an object of the present invention to provide a coating device which can effectively prevent the above problems and which requires a small amount of coating liquid for coating.

28 Structure of the Invention The present invention provides a coating method in which an object to be coated having a concave portion is immersed in a coating liquid stored in a coating tank, and the object to be coated is pulled up to apply the coating liquid to the object to be coated. In the apparatus, a convex portion is provided on the inner wall of the coating tank, and the convex portion is configured to be inserted into the concave portion when the object to be coated is immersed, and pressure control means for controlling the pressure in the concave portion. The present invention relates to a coating apparatus characterized in that the pressure control means is small (both consisting of a piston and a cylinder).

The present invention will be explained in detail below.

Fig. 1 shows the coating device, Fig. 1(a) is a schematic partial sectional view, Fig. 1Cb') is a sectional view showing the coating tank, and Fig. 1(c) is a sectional view showing the state in which the base drum is immersed. It is.

A convex portion 3 is provided on the bottom inner wall 2a of the coating tank 2, and a hollow portion 3a is formed inside the convex portion 3. This convex portion 3 is a distinctive feature not seen in the prior art.

That is, a lid 15 is joined to the upper end of the base drum 4 via an O-ring 16, and this lid 15 is fixed to an arm 35 via a gripper 18 (see FIG. 1(c)). In this case, the gripping tool 17 is omitted from the illustration). The stand U is provided with a drive means (servo motor) not shown, and the arm 35 is driven up and down as shown by arrows C and D, and the base drum 4 is also moved up and down as shown by arrows C and D accordingly. The gripping tool 18 is provided with a through hole 17, and the base drum hollow portion 4c has an open lower opening. It also communicates with a pressure control mechanism 40, which will be described later, via a tube. The pressure control mechanism 40 consists of a cylinder 39 and a piston 38, and has the function of keeping the pressure within the hollow portion 4c within a certain range when the base drum 4 is immersed and pulled up.

The operation of this coating device will be described below.

First, from the state shown in FIG. 1(a), the base drum 4 is immersed in the coating liquid 1 as shown by arrow C by driving a servo motor (not shown), and the state shown by the - dotted chain line (FIG. 1(c) )
). The inner diameter of the hollow part 4c is made slightly larger than the outer diameter of the convex part 3 to prevent the inner circumferential surface 4d of the base drum 4 from coming into contact with the outer circumferential surface 3b of the convex part 3 when the base drum 4 is immersed. It has become. At this time, as the immersion of the base drum 4 progresses, the air in the hollow part 4c is removed by the convex part 3, and the pressure of the coating liquid 1 is also applied, so the pressure in the hollow part 4c increases. . On this occasion,
The servo motor that drives the base drum 4 is connected to another servo motor (not shown) that drives the piston 38 via a synchronization mechanism (not shown). Then, as the immersion of the base drum 4 progresses, the piston 38 is driven from the position shown by the solid line to the position shown by the dashed-dotted line in synchronization with this. Along with this operation,
The air in the hollow part 4c flows as shown by arrow A and enters the space 3.
7, the pressure within the hollow portion 4c, and thus the pressure of the entire system, is maintained within a certain range, and air within the hollow portion 4c is prevented from leaking into the coating liquid.

When the immersion of the base drum 4 is completed, the piston 38
moves to the position indicated by the dashed line. At this time, as a result of keeping the pressure in the hollow part 4c constant, the coating liquid level is at position 1.
c, and rises slightly by the volume of the space 140 in the region sandwiched between the inner circumferential surface 2b of the coating tank side wall and the outer circumferential surface 4e of the base drum. As a result, the base drum outer circumferential surface 4e is immersed up to a predetermined position 4a in the coating liquid.

Next, the base drum 4 is pulled up as shown by the arrow to bring it into the state shown by the solid line in FIG. 1(a). In this case, as the base drum 4 is pulled up, the pressure inside the hollow portion 4c decreases, contrary to what was described above. In this case as well, the motor that drives the base drum 4 and the motor E that drives the piston shaft are synchronized as the base drum 4 is lifted up.

The piston 38 is driven from the position shown by the dashed line to the position shown by the solid line. As this process progresses, space 3
The air in 7 flows as shown by arrow B and flows into the base drum hollow part 4c, and the pressure in the hollow part 4c, and by extension the pressure of the entire system, is maintained within a certain range, and the pressure in the hollow part 4c is maintained within a certain range.
This also prevents the air inside from leaking into the coating liquid.

When the lifting of the base drum 4 is completed, the piston 38 moves to the position shown by the solid line. At this time, the coating liquid level returns to the original position 1a, and coating is performed on the outer circumferential surface 4e of the base drum up to the height of the predetermined position 4a.

Here, the degree of volume change (expansion) of the space 37 due to the immersion of the base drum 4 will be briefly described.

The pressure P in the hollow portion 4c when the base drum 4 is in contact with the surface of the coating liquid is equal to the atmospheric pressure P.

That is, P=P itself (1) Next K, when the immersion of the base drum 4 is completed, the coating liquid level is at position 1.
If the difference in height between a and 1c is , (the rise in the liquid level due to immersion is negligible, it is ignored), then it is the gravitational acceleration.

The volume of air trapped in the hollow portion 4c at the moment when the base drum 4 contacts the liquid surface V1. ．． If the volume of air trapped in the space 37 at that time is t6, then the pressure P,
The volume of the entire system under is (V, , + V, ,
). However, tube n etc. are ignored.

Do a little. Therefore, due to the air flow shown by arrow A, the piston 38 moves as shown by the dashed line, and the volume of the space 37 becomes v! It increases to l. The volume of the entire system is (V, l
+Vll) ,! Jj le.

The above numerical relationship is shown below.

Pressure　　　　　P6〈PI Volume on the base side V, ・> V,.

Volume of space 37 V,,<V□ Volume of entire system vl. +V,. ＞V,, ＋
V.

Among the above, ■10, ■. , ■Since P is known in advance, the size of h is set (that is, the position 1c of the coating liquid level is set), and P is determined accordingly.

or measure PI, set the volume of the space 37 according to each of the above numerical values, and drive the piston 38 according to the set value of the volume of the space 37, then the coating device shown in Fig. 1 can be used. By performing the above-described dipping operation and controlling the pressure in the hollow portion of the base drum 4cK, it is possible to easily maintain the liquid level at the position 1c.

It should be noted that since Boile-Charles' law holds true for each of the above numerical values, it is considered that the following equation (3) can be used.

P@+1(v1o+vI)=P, 11(vll+v□)
(3) If the above is further generalized, it can be considered as follows.

That is, if the pressure in the system at a certain point during immersion is P, the volume on the substrate side is vl, and the volume of the space 37 is K, then the following (
4) It is considered that the formula holds true.

P・(V, +V, )=C・・・・・・・・・・・・
(4) However, C is a constant.

What is necessary is to drive the piston 38 so that the volume V changes according to the above equation (4).

Above, we have outlined various relationships when the base drum 4 is immersed.
The degree of zero volume change (shrinkage), the relationship with pressure, etc. are also the same as in the case of immersion described above.

It is preferable that the pressure P in the system is usually within the range of 300 to 500 mmAq. Of course, this is the specific gravity of coating liquid 1,
This is a value that should be adjusted depending on the solvent, the vertical length of the base drum 4, etc., and the above range cannot necessarily be determined uniformly.

Usually, it is considered preferable that the specific gravity of the coating liquid 1 is within the range of 0.8 to 1.5.

According to such a coating device, even when the base drum 4 is immersed, the level of the coating liquid rises only slightly from the height of the position 1a. There is very little vertical movement.

Therefore, no dry matter is generated on the inner circumferential surface 2b of the side wall of the coating tank (it is possible to significantly reduce the frequency of occurrence of foreign particle defects, and it is also possible to suppress changes in the composition and deterioration of the coating liquid 1. It also improves productivity, prevents waste of raw materials, and reduces costs.

Moreover, what is noteworthy is that due to the presence of the convex portion 3, the amount of coating liquid 1 required for coating can be reduced. That is, in the past, as shown in FIG. 13, the magnitude of the rise in the coating liquid level due to the immersion of the base drum 4 was ! , and thick (,
Only when the surface of the coating liquid rose from position 1b to position 1a was it possible to coat the outer peripheral surface 4e of the base drum up to the predetermined position 4a.

In other words, it is assumed that the coating liquid level does not rise to the level 5 mentioned above when the base drum 4 is immersed.

It is impossible to perform the desired coating up to the height of the predetermined position 4a.

In contrast, in the present invention, by providing the convex portion 3, this trade-off can be resolved. That is,
As shown in FIG. 1(b), if we assume that the convex portion 3 is not provided on the bottom inner wall 2a of the coating tank, the coating liquid level should exist at the position 4b shown by the dashed line. Even if the base drum 4 is immersed as shown in FIG. 1(c),
It is not possible to perform the desired coating up to the height of the predetermined position 4a.

However, by providing the convex part 3, the coating liquid 1 is removed by the volume of the convex part 3, and the liquid level is at the position 1a shown by the solid line.
It increases significantly by 11. Therefore, in this state, as shown in FIG. 1(C), the base drum 4
By immersing the liquid, it is possible to suppress the vertical movement of the coating liquid level 1a as described above, and simultaneously perform the desired coating up to the height of the predetermined position 4a.

Furthermore, when the base drum 4 is immersed and pulled up, the pressure inside the base drum hollow portion 4c is maintained at a preset value by the function of the pressure control means described above. This prevents the coating liquid 1 from entering into the hollow part 4c of the base drum, and also prevents the air in the hollow part 4c from leaking into the coating liquid 1. As a result, the liquid level of the coating liquid can be lowered as shown in FIG. It can be held at position 1c shown in c). Therefore, the inner circumferential surface 4d of the base drum
It is possible to prevent the coating liquid from being applied or adhering to the surface.

That is, if the coating liquid 1 were to be applied to the inner circumferential surface 4d, a complicated operation would be required to remove the coating liquid (11) from the inner circumferential surface 4d, and the coating liquid 1 would also be wasted, resulting in waste of materials, etc. This is inconvenient because the cost also increases. On the other hand, if the hollow part 4
If the air in c leaks into the coating liquid 1, coating defects will occur, which is inconvenient. According to the present invention, both of these problems are technically solved, and the pressure control means 40
This prevents the coating liquid 1 from entering into the hollow portion 4c of the base drum, eliminates the need for the above-mentioned complicated manual work, prevents the coating liquid 1 from being wasted, and reduces the cost of materials, etc.
In addition, coating defects due to air leakage can be prevented.In addition to these, the pressure control means in this example essentially consists of a piston and a cylinder, and has a simple structure, which allows for miniaturization of the device and cost reduction. It is. Furthermore, since the base drum is shaped like a cylindrical drum, synchronization is considered to be easy. For example, if the base is “gourd-shaped”,
It is difficult to synchronize pressure control with pistons because the speeds differ between the thick and thin parts. The present invention facilitates synchronization when the cross-sectional areas of the piston and the base drum are each constant in the longitudinal direction. Furthermore, the piston is motor driven so that the pressure control is mechanically precise.

As described above, according to the coating device of this example, it is possible to suppress the vertical movement of the coating liquid level that occurs when the substrate drum is immersed and pulled up, and at the same time, it is possible to reduce the amount of coating liquid required, and It can prevent the coating liquid from being applied or attached to the surrounding surface, and the pressure can be easily controlled mechanically.

It can be carried out reliably, and the mechanism is simple and costs can be reduced.

Figure 2 shows another coating device (a so-called overflow type), in which (a) is a schematic partial sectional view and (b) is a schematic partial cross-sectional view.
) is a cross-sectional view showing the coating tank, and FIG.

Also in the coating device shown in FIG. 2, the bottom inner wall 2a of the coating tank 2 is
Remarkable features include the provision of a convex portion 3 and the provision of a pressure control mechanism 40 for controlling the pressure within the hollow portion 4c of the base drum.

Note that, except for the above-mentioned points, the coating device shown in FIG.
The coating device is the same as the coating device shown in the figure, and the same functional members are given the same reference numerals and their explanations are omitted, and the circulation system such as tanks and pumps is omitted from the illustrations except in Fig. 2 (a). (The same applies to the coating apparatuses shown in FIGS. 6 to 8).

The operation of this coating device is similar to that of FIG.

First, from the state shown in FIG. 2(a), the base drum 4 is immersed in the coating liquid 1 as shown by the arrow C to bring it into the state shown by the - dotted chain line (the state shown in FIG. 2(c)). The inner diameter of the hollow part 4c is slightly larger than the outer diameter of the convex part 3, so that the inner peripheral surface 4d of the base drum 4 and the outer peripheral surface 3b of the convex part 3 do not come into contact with each other when the base drum 4 is immersed. At this time, as the immersion of the base drum 4 progresses, the hollow part 4
Although the pressure in the hollow part 4c increases, the pressure control mechanism 40 operates in the same manner as described above, and the pressure in the hollow part 4c is kept constant.

When the immersion of the base drum 4 is completed, the pressure in the hollow portion 4c is kept constant, and as a result, the coating liquid level drops to the level of the position 1c. As a result, the base drum outer circumferential surface 4e is immersed up to a predetermined position 4a in the coating liquid.

Next, the base drum 4 is pulled up to the state shown by the solid line in FIG. 2(a). In this case, as the base drum 4 is pulled up, the pressure inside the hollow section 4c decreases, contrary to the above, but the pressure control mechanism 40 operates in the same manner as described above, and the pressure inside the hollow section 4c decreases. The pressure inside remains constant.

When the lifting of the base drum 4 is completed, the coating liquid level returns to the original position 1aK, and coating is performed on the outer circumferential surface 4e of the base drum up to the height of the predetermined position 4a.

According to such a coating device, all the advantages of the conventional overflow type coating device can be fully enjoyed. That is, the height of the coating liquid level is kept constant even when the base drum 4 is immersed, and therefore, no dry matter is generated on the inner circumferential surface 2b of the side wall of the coating tank, and the frequency of occurrence of foreign particle defects is significantly reduced. It is also possible to suppress changes in components and deterioration of the coating liquid 1. Therefore, coating productivity can be improved, waste of raw materials can be prevented, and costs can be reduced.

Moreover, what is particularly noteworthy is that due to the presence of the convex portion 3, less amount of the coating liquid 1 is required for coating. That is, conventionally, as shown in FIG. 14, it is necessary to fill the coating tank 2 and store a sufficient amount of coating liquid in the circulation system such as the tank 12. was needed.

In contrast, in the present invention, by providing the convex portion 3, the coating liquid 1 is removed by the volume of the convex portion 30, and the amount of coating liquid required to fill the coating tank is greatly reduced. Moreover, as the amount of coating liquid stored in the coating tank decreases,
There is also less ii in the circulatory system, and the overall amount of coating liquid required is significantly reduced. Further, as the amount of coating liquid decreases, the circulation amount (speed) of the coating liquid can be reduced to downsize the pump, and the filtration area of the filter can also be reduced.

By reducing the amount of coating liquid required and downsizing the equipment,
It is possible to reduce the cost of raw materials, etc., and even when the coating liquid finally reaches its usage limit, the amount of discarded or replaced coating liquid is small, which also prevents wastage of raw materials. It's advantageous.

Moreover, like the coating device shown in FIG. 1, the pressure control mechanism 40
Due to the function k, even when the base drum 4 is immersed and pulled up, the pressure inside the hollow part 4c is maintained at a preset value by the control of the drive motor of the piston 38, and therefore the coating liquid is not applied to the inside of the hollow part 4C. 1 and air leakage into the coating liquid 1 can be prevented. As with the coating device shown in Fig. 1, this eliminates the need for the above-mentioned complicated operations, prevents wastage of the coating liquid 1, and reduces the cost of materials, etc. It is also possible to prevent coating defects from occurring.

Further, the piston is driven by a motor, the pressure inside the hollow portion 4c can be easily and reliably controlled, and the mechanism is simple and costs can be reduced, similar to the coating device shown in FIG.

As mentioned above, with the coating device of this example, while fully enjoying the advantages of the conventional overflow type,
The required amount of the coating liquid can be reduced, and it is also possible to prevent the coating liquid from being applied or attached to the inner circumferential surface of the base drum, and pressure control is easy and reliable, and cost reduction can also be achieved.

FIG. 3 is a sectional view showing another coating device.

In this example, the height of the convex portion 13 is set higher than the liquid level position 1a. In the figure, 13a is a hollow portion, and 13b is an outer peripheral surface of a convex portion. The other parts are the same as the coating device shown in FIG. 1, and the base drum hollow portion 4c communicates with a pressure control mechanism 40 (not shown) (see FIG. 1) via an open lower part. These points also apply to the coating apparatuses shown in FIGS. 4 and 5.

FIG. 4 is a sectional view showing still another coating device.

In this example, a cylindrical convex portion 23 having an opening 23c above is provided. The upper end of the convex portion 23 is set higher than the liquid level position 1a to prevent the coating liquid 1 from flowing into the space 23a. Note that 23b is the outer peripheral surface of the convex portion.

FIG. 5 is a sectional view showing still another coating device.

In this example, the open lower is provided on the bottom surface 2c of the coating tank.

FIG. 6, FIG. 7, and FIG. 8 are sectional views showing still other coating apparatuses, all of which are of the overflow type.

In the example shown in FIG. 6, the height of the convex portion 13 is set higher than the liquid level position 1a. The other parts are the same as the coating device shown in FIG. 2, and the base drum hollow portion 4c communicates with a pressure control mechanism 40 (not shown) K (see FIG. 2) via an open lower part. These points also apply to the coating apparatuses shown in FIGS. 7 and 8.

In the example shown in FIG. 7, an opening 53c is provided at the bottom of the convex portion 53.
is provided, and a space 53a communicates with the outside.

In addition, in the figure, 53b represents the outer circumferential surface of the convex portion.

In the example shown in FIG. 8, a cylindrical convex portion n having an opening 23c above is provided. The upper end of the convex portion 23 is set higher than the liquid level position 1a.

FIG. 9 shows yet another coating device.

The drive mechanism and the like are not shown.

In this example, the piston rod 18 is joined to the lid body 15. The base drum 4 is immersed and pulled up using the piston rod 1.
This is done by driving B in the direction of arrow C%D.

In this example as well, the pressure control means 60 consists of a piston 48 and a cylinder 39, and the cylinder 39 is fixed. The operation of the pressure control means 600 is similar to that of the pressure control means 40 described above (see FIGS. 1 and 2), but the point is that when the base drum 4 is immersed, the cylinder 48 moves in the direction of arrow C, and the base drum When the base drum 4 is pulled up, the cylinder 48 moves in the direction of the arrow, and along with these movements, the space 37 expands and contracts, and the pressure inside the base drum hollow part 4c is controlled. In this example, the pressure can be mechanically controlled by appropriately selecting the diameter of the cylinder 39. For example, the inner diameter of the cylinder and the outer diameter of the convex portion may be approximately equal.

When the present invention is applied to the coating formation of the constituent layers of an electrophotographic photoreceptor, especially the photosensitive layer, it is possible to suppress the occurrence of image defects (for example, black spots) caused by foreign object defects, improve the productivity of the photoreceptor, and reduce the cost of raw materials. This is particularly advantageous in terms of cost reduction (for example, carrier-generating substances).

Further, it is believed that the present invention is particularly effective when applied to an overflow type coating device and applied to a coating liquid for forming a carrier generation layer. This also applies to a single-layer photosensitive layer containing both a particulate carrier-generating substance and a carrier-transporting substance. This is because these coating liquids are usually pigment dispersion systems in which granular pigments are dispersed in the liquid, and many of the pigments are easily changeable in crystal form, resulting in changes in viscosity due to circulation and changes in the crystal form of the pigment. This is because it has a large influence. Therefore, if the amount of coating liquid and the amount of circulation of the coating liquid can be reduced compared to the coating apparatus K of the present invention, it is considered to be more advantageous in terms of cost.

10 to 12 each show an example of an electrophotographic photoreceptor in which layers are formed by coating according to the present invention.

In the photoreceptor shown in FIG. 10, a carrier generation layer 31 is provided as a first layer on a conductive substrate 30, and a carrier transport layer 32 is provided as a second layer on the carrier generation layer 31. The photoreceptor in Fig. 11 has a conductive substrate (material).
When viewed from the side, a carrier transport layer 32 as a first layer and a carrier generation layer 31 as a second layer are sequentially laminated.

The photoreceptor shown in FIG. 12 has, as a first layer, a photosensitive layer 33 having a single-layer structure containing both a carrier-generating substance and a carrier-transporting substance.

Of course, the number and types of coating layers coated and formed by the coating apparatus of the present invention are not limited to the examples shown in FIGS. It can be set freely according to the design intention.

For example, when viewed from the conductive substrate side, the first layer and the second layer are an undercoat layer and a photosensitive layer with a single layer structure, the photosensitive layer with a single layer structure, and a protective layer. The second layer and the third layer are respectively a subbing layer, a carrier transport layer, and a carrier generation layer; a carrier generation layer, a carrier transport layer, and a protective layer; a first layer, a second layer, a third layer, and a third layer; 411 is an undercoat layer, a carrier generation layer, a carrier transport layer, and a protective layer, respectively, or an undercoat layer, a carrier transport layer, and a carrier generation layer.

Examples include those that are protective layers.

The undercoat layer is acrylic, methacrylic, vinyl chloride,
Vinyl acetate, epoxy, polyurethane, phenol, polyester, alkyd, polycarbonate, silicone, melamine, vinyl chloride/vinyl acetate copolymer, vinyl chloride/vinyl acetate maleic anhydride copolymer, etc. It can be formed from various resins.

The carrier generation layer is made of, for example, a monoazo dye, a disazo dye,
Azo dyes such as trisazo dyes, perylenic anhydride,
Perylene dyes such as perylenic acid imide, indigo dyes such as indigo and thioindigo, anthraquinone,
Polycyclic quinones such as pyrenequinone and furapanthrones, quinacridone pigments, bisbenzimidazole pigments, indathrone pigments, squarelyricum pigments, metal phthalocyanine pigments, 7-thalocyanine pigments such as metal-free 7-thalocyanine, biryllium salt pigments, It can be formed by dissolving or dispersing various known carrier-generating substances, such as a eutectic complex formed from a thiapyrylium salt dye and polycarbonate, in a solvent together with a suitable binder resin and, if necessary, a carrier-transporting substance, and coating the solution.

The carrier transport layer can be made of electron-accepting substances that easily transport electrons, such as trinitrofluorenone or tetranitrofluorenone, as well as polymers with side chains of heterocyclic compounds such as poly-N-vinylcarbazole, and triazoles. Various known holes such as derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives, polyarylalkali/derivatives, phenylenediamine derivatives, hydrazone derivatives, amino-substituted chalcone derivatives, triarylamine derivatives, carbazole derivatives, stilbene derivatives, phenothiazine derivatives, etc. It can be formed by dissolving a gear transport material that is easy to transport in a solvent together with a suitable binder resin, coating, and drying.

Further, a photosensitive layer having a single layer structure can be formed by dissolving or dispersing the carrier-generating substance as described above in a solvent together with a suitable carrier-transporting substance and a binder resin, and coating the solution.

The above binder resins include, for example, polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene copolymer resin (for example, styrene-butadiene copolymer) , styrene-methyl methacrylate copolymer), acrylonitrile copolymer resin (e.g. vinylidene chloride-acrylonitrile copolymer, etc.), vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer , silicone resins, silicone-alkyd resins, phenolic resins (e.g. phenol-formaldehyde resins).

Preferred are film-forming polymers such as m-cresol-formaldehyde resin, etc.), styrene-alkyd resin, poly-N-vinylcarbasol, polyvinyl butyral, and polyvinyl formal.

In addition, the protective layer contains polyurethane, polyethylene, polypropylene, etc. as the carrier transporting substance and the binder resin.
Acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, phenol resin, polyester resin, polycarbonate resin, silicone resin, melamine resin, etc., and copolymers containing two or more repeating units of these resins. It can be formed from resin or the like.

Solvents used in coating and forming the carrier transport layer, carrier generation layer, etc. include acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2-)IJ / Lorethane, 1,1,2
．． 2-tetrachloroethane, 1,1.2-)dichloropropane, 1゜1.2.2-tetrachloropropane, 1,
2.3-trichloropropane, 1,1.2-trichlorobutane 7.1.2,3.4-tetrachlorobutane, tetrahydrofuran, monochlorobenzene, dichlorobenzene, dioxane, methanol, ethanol, inglobanol, Ethyl acetate, butyl acetate, dimethyl sulfoxide, methylcellosolve acetate, n-butylamine,
Examples include diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N,N-dimethylformamide, and the like.

Further, as a solvent for dissolving the carrier transport substance and binder resin to form a coating liquid, a solvent that can uniformly dissolve these is selected, and a solvent with a boiling point (bp) of 80°C is selected.
A temperature of 150°C to 150°C is preferable, and a temperature of 90°C to 120°C is more preferable. If the boiling point is less than 80° C., drying is too fast, resulting in dew condensation and blurring, and drying is too fast, making leveling impossible and making it difficult to obtain a smooth photosensitive layer. Furthermore, if the temperature exceeds 150°C, dripping and uneven coating are likely to occur.

Specifically, dichloromethane, 1,2-dichloroethane (bp=83.5°C), 1,1.2-)dichloroethane (bp=113.5°C), 1,4-dioxane (bp
= 101.3°C)% benzene (bp = 80.1°C), toluene (bp = 110.6°C), OI In *
p.

-xylene (bp=138-144°C), tetrahydrofuran, dioxane, monochlorobenzene and the like. Further, even if the boiling point of a solvent is not in the range of 80°C to 150°C, the boiling point can be adjusted by mixing a high boiling point solvent and a low boiling point solvent.

Further, as a solvent for forming a carrier generation layer and a photosensitive layer having a single layer structure, it is necessary to dissolve the binder resin and the carrier transport substance contained if necessary, and to transfer the carrier generation substance to a particle size of preferably 2 μm or less, more preferably 1 μm or less. A material that can be dispersed in the form of fine particles and provide a stable dispersion, and that does not unduly dissolve or swell the underlying carrier transport layer, subbing layer, etc., if present, is selected.

In particular, among the above, toluene, chloroform, dichloromethane, 1,2-dichloroethane, 1,1゜2-trichloroethane, 1,1,2.2-tetrachloroethane, tetrahydrofuran, monochlorobenzene, and dioxane are used in the carrier generation layer. , is a preferred solvent for both carrier transport layers.

The coating liquid used in the present invention may contain other substances in addition to those mentioned above. For example, the inclusion of a siloxane compound has the effect of smoothing the coating surface. Examples of the siloxane compounds include dimethylpolycloxane and methylphenylpolysiloxane.

The amount added is preferably 1 to 10000111 ml, more preferably 10 to 100011'1 ml, based on the total amount of the coating liquid.

Further, in the photosensitive layer, for the purpose of reducing residual potential and memory, an electron-accepting substance such as succinic anhydride, maleic anhydride, or phthalic anhydride is preferably added to the carrier-generating substance 1.
It can be added at a ratio of 0.1 to 100 parts by weight per 00 parts by weight. Furthermore, the photosensitive layer may contain an organic amine such as butylamine or diisobutylamine in a mole number equal to or less than that of the carrier-generating substance, if necessary, for the purpose of improving sensitivity and reducing memory.

In addition, it is also possible to form a photoreceptor using the same binder resin and the same solvent as in the coating solution for the carrier transport layer and the coating solution for the carrier generation layer. In that case, the productivity of the photoreceptor and the This has the advantage of further improving performance.

In other words, if the same binder resin can be used, the barrier between the carrier generation layer and the carrier transport layer will be reduced, and the carriers generated during light irradiation will be smoothly injected and transported to the carrier transport layer, which will improve the photoreceptor's sensitivity characteristics, residual potential, and memory. Characteristics etc. are also improved.

Furthermore, if the same binder resin, solvent, etc. can be used in common, there is an advantage that the coating process becomes easier, more accurate, and faster.

Although the shape, material, etc. of the conductive substrate are not particularly limited, a cylindrical shape is preferably used. In addition, the material may be a metal plate such as an aluminum alloy, a metal drum, or a conductive thin layer made of a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum, palladium, or gold, such as coating, vapor deposition, or lamination. A material provided on a substrate such as a patterned plastic film by the above method is used.

More specifically, the following method is selected for forming the carrier generation layer and the photosensitive layer having a single layer structure.

(a) A method of applying a solution in which a carrier-generating substance is dissolved in a suitable solvent, or a solution in which a binder is added and mixed and dissolved.

(b) A method in which a carrier-generating substance is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., and a binder is added as necessary to mix and disperse the obtained dispersion, and the resulting dispersion is applied.

Dispersing the particles under the action of ultrasound in these methods allows for homogeneous dispersion.

The viscosity of the coating liquid for forming photoreceptor constituent layers such as the photosensitive layer, undercoat layer, and protective layer is preferably within the range of 5 to 500 cp (centivoise), and more preferably within the range of Hro to 300 cp. preferable. If the viscosity is smaller than the above range, the coating film tends to sag (the film tends to be thicker at the bottom of the drum than at the top, and if it is larger than the above range, the viscosity of the coating liquid in the coating tank will become uneven). Easy (There is a tendency to cause uneven film thickness in the coating film.)

The thickness of the carrier transport layer after coating and drying is preferably in the range of 5 to 50 μm. If it is less than 5 μm, the desired charging ability (
±500 to 800 V) may not be obtained, and a sufficient carrier transport function may not be achieved.If it exceeds 9 μm, the charging ability is too high (100 OV or more).

Image quality tends to deteriorate, resolution decreases, and residual potential tends to become large. The amount of carrier transport substance per 100 parts by weight of binder resin is from 20 to 200 parts by weight, preferably from 30 to 150 parts by weight.
It is best to keep it within the range of parts by weight. If it is less than 4 parts by weight, the carrier transport function will be low, sensitivity will decrease and residual potential will increase, and if it exceeds 200 parts by weight, the viscosity and surface tension will be large and coating processability will tend to deteriorate.

Further, the carrier generation layer after coating and drying usually has a thickness of 0.05 to 10 μm. If there is no groove of 0.05 μm, carrier generation ability is insufficient, and uniform coating is difficult ((,1
If it exceeds 0 μm, generated carriers will be trapped and sensitivity will tend to decrease. The amount of the carrier-generating substance per 100 parts by weight of the binder resin is preferably 5 to 500 parts by weight, preferably 20 to 100 parts by weight. If the carrier-generating substance is less than 5 parts by weight, the carrier-generating ability will be insufficient, and if the carrier-generating substance is less than 5 parts by weight,
If the weight part is exceeded, carriers will be trapped and sensitivity will decrease.
Memory generation is likely to occur. Further, the amount of the carrier transport substance to be included if necessary is 20 to 200 parts by weight, preferably 30 to 150 parts by weight, per 100 parts by weight of the binder resin.
It is best to keep it within the range of parts by weight.

In the case of a single-layer photosensitive layer, the layer thickness after coating and drying is 10 to 5.
Preferably, it is 0 μm. If the layer thickness is smaller than the above range, the charging ability will be low and the printing durability will be poor. On the other hand, if the layer thickness is larger than the above range, the residual potential increases and sufficient transport ability cannot be obtained (or tends to become so).

The thickness of the protective layer provided on the surface of the photoreceptor is 0.01 to 1μ
It is preferable to set it within the range of m. Further, the thickness of the subbing layer (or intermediate layer, barrier layer, adhesive layer, etc.) provided between the photosensitive layer and the conductive substrate is preferably within the range of 0.01 to 2 μm.

The ratio of the diameter of the base drum to the outer diameter (diameter) of the cylindrical convex portion is preferably within the range of 100:98 to 100:50. From this K, the volume of the convex portion is also large enough to push up the coating liquid level, and in some cases,
It is considered that there is no possibility that the base drum and the convex portion will come into contact with each other.

In addition, when forming the photoconductor constituent layers, blade coating,
Coating methods such as spray coating and spiral coating may be used in combination.

Examples of the present invention will be described in more detail below, but the present invention is not limited thereto.

<Preparation of coating liquid> First, a coating liquid was prepared as follows.

Preparation of coating liquid for carrier generation layer formation 1. 2-Dichloroethane (manufactured by Kanto Kagaku Co., Ltd.) (boiling point 83.
Polycarbonate (Panlite-L-1250, manufactured by Konjin Kasei Co., Ltd.) 5 as a binder resin in 5°C) 100 d.
．． 0g was dissolved. In addition, as a carrier generating substance, 4.
10 g of 10-dibromoanthrone was ground in a ball mill for 24 hours, the above solution was added thereto, and the solution was further dispersed in a ball mill for 24 hours to obtain a coating solution (dispersion) for forming a carrier generation layer with a viscosity of 160 cp. .

Coating liquid for carrier transport layer formation 1,2-dichloroethane (manufactured by Kanto Kagaku Co., Ltd.) 1000d
100 g of polycarbonate (Panlite-L-1250, manufactured by Kinjin Kasei Co., Ltd.) was dissolved therein as a binder resin, and 1,1-bis(4-N,
A coating solution for forming a carrier transport layer was prepared by dissolving 100 g of N-dibenzylamino-2-methylphenyl) normal butane.

<Coating experiment 1> Example 1 A coating experiment was conducted using the coating apparatus shown in FIG.

The diameter of the coating tank 2 is 120 mm, the height is 350 mm,
The diameter of the convex portion 3 was 75 am, and the height was 300 M.

The coating liquid for forming a carrier generation layer and the coating liquid for forming a carrier transport layer are stored in respective coating tanks, and the carrier generation layer and the carrier transport layer are sequentially coated on the base drum, and then One hundred photographic photoreceptors were manufactured in succession. However, the base drum is 80mmφx350
A cylindrical conductive substrate made of aluminum and having a diameter of 1 mm was used.

Comparative Example 1 Using the coating tank shown in FIG. 13 and under the same conditions as in Example 1, 100 negatively charged photoreceptors were continuously manufactured.

However, the diameter of the coating tank should be 80 mm and the height should be 350 mm.
And so.

<Results of Coating Experiment 1> Example 1 For the carrier generation layer, the amount of coating liquid was 21 initially and the additional amount was 0.51, so a total of 2.51 was required.

Regarding the carrier transport layer, the amount of coating liquid was 21 initially and 11 additionally, totaling 31.

Out of 100 photoconductors, 90 are good and the remaining 1
A coating defect (foreign object defect) was observed in 0 pieces.

Comparative example 1 What is the amount of coating liquid for the carrier generation layer and carrier transport layer?

Both were the same as in the example.

Furthermore, out of 100 photoreceptors, 80 were good, and the remaining 20 had significant coating defects (foreign object defects).

As described above, according to the coating apparatus of Example 1, although the required amount of coating liquid is about the same, deterioration of the coating liquid is suppressed, and the frequency of occurrence of coating defects is significantly reduced. It is clear that productivity has improved.

<Coating experiment 2> Example 2 A coating experiment was conducted using the coating apparatus shown in FIG.

The coating tank 2 had a diameter of 240 mm and a height of 350 m, and the convex portion 3 had a diameter of 190 m and a height of 300 m.

The above-mentioned coating solution for forming a carrier generation layer and coating solution for forming a carrier transport layer are placed in respective coating tanks, and the carrier generation layer and the carrier transport layer are sequentially applied and formed on the base drum, and electrophotography using negative charging is performed. 100 photoreceptors were manufactured continuously. However, the base drum is 200mmφx35
A 0 mm aluminum cylindrical conductive substrate was used.

Comparative Example 2 Using the coating bath shown in FIG. 14, 100 negatively charged photoreceptors were continuously manufactured under the same conditions as in the example. However, the diameter of the coating tank should be 240 mm and the height should be 350 mm.
And so.

<Results of Coating Experiment 2> Example 2 Regarding the carrier generation layer, the amount of coating liquid was initially 101 (61 in the coating tank, 41 in the piping), and an additional amount of 1! So, a total of 111 were required.

Regarding the carrier transport layer, the coating liquid amount was initially 10 Il.
(61 for the coating tank, 47 for the piping), and 21 more for a total of 121.

Out of 100 photoreceptors, 96 were good.

Comparative Example 2 Regarding the carrier generation layer, the amount of coating liquid was initially 221 (6 J for 161% piping in the coating tank), and the additional amount was 11, for a total of 23 J.
It was necessary.

Regarding the carrier transport layer, the amount of coating liquid was initially 221 (161 for the coating tank and 61 for the piping), and 21 was added for a total of 241.

Out of 100 photoreceptors, 96 were good.

Coating device> In addition, the pump capacity was set to a flow rate of 201/m1n (Comparative example 2).
It was possible to reduce the size from 2 J/m1n (Example 2). In addition, the filtration area of the filter was 130,000 - (Comparative Example 2)
The size could be reduced from 1300 crA (Example 2).

As described above, it is clear that according to the coating apparatus of Example K, the required amount of coating liquid can be suppressed to less than half, and the capacity of the pump and the filtration area of the filter can also be reduced.

Although the present invention has been illustrated above, the embodiments of the present invention are not limited to the above embodiments, and various modifications are possible.

For example, the dimensions, shapes, positions, etc. of the coating tank, the object to be coated, and the convex portion may vary.

It is also possible to use various pressure control means in combination, for example, those whose volume changes in response to increases and decreases in the pressure in the hollow part of the base drum (1! L ship, bellows, etc.), and those with a chave etc. It is conceivable to connect it to the hollow part of the base drum through the hollow part of the base drum.

According to the coating device of the present invention, a convex portion is provided on the inner wall of the coating tank, and the convex portion is inserted into the concave portion when dipping the object to be coated. Since the coating liquid is removed by the convex part in the coating tank, the object to be coated can be coated to a predetermined position with a smaller amount of coating liquid corresponding to the amount of liquid that is removed, and it is also possible to coat the object to be coated to a predetermined position. In this case, the vertical movement of the coating liquid can be reduced by the volume of the convex portion. As a result, it is possible to suppress the formation of dry matter on the side wall of the coating tank, thereby significantly reducing the frequency of occurrence of foreign substance defects, and also to reduce the required amount of coating liquid, thereby achieving cost reduction.

In addition, since a pressure control means is provided to control the pressure inside the recess of the object to be coated, K
By controlling the pressure within the recess, it is possible to prevent the coating liquid from entering the recess and preventing air within the recess from leaking into the coating liquid. Therefore, it is possible to avoid applying or adhering the coating liquid to the inside of the recess, eliminating the need for waste of the coating liquid and the complicated work of removing the applied and adhered coating liquid, and also preventing coating defects due to air leakage. .

Furthermore, since the pressure control means consists of at least a piston and a sill, pressure control can be easily and accurately performed by the operation of the piston, and the mechanism is relatively simple.

[Brief explanation of the drawing]

1 to 9 show embodiments of the present invention. Fig. 1 shows the coating device, Fig. 1(a) is a schematic partial sectional view showing the coating amount, Fig. 1(b) is a sectional view showing the coating tank, and Fig. 1(c) shows the base drum for applying the coating liquid. 2 shows another coating device, FIG. 2(a) is a schematic partial sectional view showing the coating device, FIG. 2(b) is a sectional view showing the coating tank, c) is a cross-sectional view showing the state in which the base drum is immersed in the coating liquid; FIG. 2 is a sectional view showing the device. FIG. 10, FIG. 11, and FIG. 12 are sectional views each showing an example of an electrophotographic photoreceptor. FIGS. 13 and 14 are sectional views showing conventional coating devices, respectively. In addition, in the symbols shown in the drawings, 1......Coating liquid la, lb, lc...Position 2 of the coating liquid level... Coating tank 2d...Coating tank side wall 2e...Coating tank side wall upper part 3.13, n
, 53... Convex portions 3a, 13a...
...Hollow parts 3b, 13b, 23b, 53b...
......Convex portion outer peripheral surface 4...Base drum 4a...Predetermined position 4c...Hollow portion 4d... ...Base drum inner peripheral surface 7...
...Opening 9...Dry solids 23a, 53a, 37...Space n.
......Chave blade, 4B...Piston 39...Cylinder chrysanthemum, 60...Pressure control means A1. ...
・・・・・・The amount of rise in the liquid level due to the convex portion is 1,・
......It is the magnitude of the vertical movement of the liquid level due to immersion. Agent Patent Attorney Aisaka Tsu Figure 7 Figure 9 - IQ$;l - Figure 10 Figure 13 Figure 9 Portion Figure 14

Claims (1)

[Claims] 1. In a coating device that applies the coating liquid to the object by immersing the object having a concave portion in a coating liquid stored in a coating tank and pulling up the object, the inner wall of the coating tank is provided with a convex portion, the convex portion is configured to be inserted into the concave portion when the object to be coated is immersed, and pressure control means for controlling the pressure within the concave portion is provided; A coating device characterized in that the control means includes at least a piston and a cylinder.