JPH01127073A - Coating apparatus - Google Patents

Abstract

PURPOSE:To effectively prevent the coating defect by the adhesion of foreign matter, by inserting the protruding part provided to the inner wall of a coating tank in the recessed part of an object to be coated when said object is immersed in the coating solution within the coating tank and controlling the pressure in the recessed part by a pressure control means. CONSTITUTION:An object 4 to be coated having a recessed part 4c is immersed in the coating solution 1 received in a coating tank 2 and drawn up to be coated with the coating solution 1. A protruding part 3 is provided to the inner wall 2a of the coating tank and inserted in the recessed part 4c when the object 4 to be coated is immersed and the pressure of the recessed part 4c is controlled by a pressure control means consisting of a tube 27, a fine differential pressure gauge 36 with a contact, relays 37A, 37B, solenoid valves 38A, 38B and a pressure pump 39. As a result, the coating defect caused by the adhesion of foreign matter can be effectively prevented and the amount of the coating solution required in coating is reduced to make it possible to achieve cost reduction.

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 cadmium sulfide as a main component have been 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°4,7-1-dinitro-9-fluorenone is described. However, this photoreceptor
Sensitivity and durability are not necessarily satisfactory. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the carrier generation function and carrier transport function to different substances in the photosensitive layer. ing. In such a so-called functionally separated electrophotographic photoreceptor,
Since substances that exhibit each function can be selected from a wide range of materials, it is possible to relatively easily produce an electrophotographic photoreceptor having arbitrary characteristics.

When coating and forming the photosensitive layer of such an electrophotographic photoreceptor, it is necessary to form the photosensitive layer with high precision and uniformity in order to maintain good sensitivity characteristics, prevent image defects such as density unevenness, and exhibit good performance as a photoreceptor. It is necessary to apply and form a thin 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. 12 shows a coating device used for dip coating.

A predetermined coating liquid 1 is contained in the coating tank 2 . At the time of dip coating, the z,u*-1ip-i cylindrical conductive substrate (hereinafter sometimes referred to as a substrate drum) 4 is immersed in the coating liquid 1 with the opening 4b facing downward, and then the lid 5 is immersed in the coating liquid 1. Grip the handle 5a and pull up the base drum 4 at a predetermined speed. However, when the base drum 4 is immersed, the air filling the hollow part 4C inside the base drum 4 causes the base drum 4 to reach the height of the outer peripheral surface 4e of the base drum 4 and the coating tank 2 (754a). The coating liquid is applied to the outer peripheral surface 4e of the drum, and a uniform coating film is formed.

At this time, the volume of the immersed portion of the base drum 4 and, therefore, the following problems arise with such a coating device.

The coating liquid 1 adheres to the inner circumferential surface 2b of the fabric side wall, and the attached coating liquid dries to produce a dried substance 9. It is believed that the dried matter S 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).

Furthermore, 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. .

As a countermeasure to this problem, Utility Model Application No. 62-591
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 a coating device, the coating liquid tends to leak from the gap between the coating tank and the pedestal, and a separate sealing member is required, making the device complicated, 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 to the outer peripheral surface of the pedestal and from drying out.

As a method for preventing such defects, a so-called overflow one-type method is known, and FIG. 13 shows a schematic cross-sectional view of a dip coating apparatus 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.
The liquid is supplied into the coating tank 2 as shown by the arrow E, and further overflows in the circumferential direction of the coating tank 2 over the upper edge 2e of the side wall 2d. More tank 12
is discharged to. 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 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, it requires several times the amount of coating liquid compared to the coating apparatus shown in Figure 12). ), 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.

C6 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.

21 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 part is provided on the inner wall of the coating tank, the convex part is inserted into the concave part when the object to be coated is immersed, and pressure control is performed to control the pressure in the concave part. The present invention relates to a coating device characterized in that a means is provided.

E, Example The present invention will be explained in detail below.

Figure 1 shows the coating device, Figure ta) is a schematic partial sectional view, Figure 1) is a sectional view showing the coating tank, and Figure 1(C) is a sectional view showing the state in which the base drum is immersed. .

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. (However, in FIG. 1 (C1, the gripping tool 18 is omitted). The stand 34 is provided with a drive means (not shown), and the arm 35 is driven up and down as shown by arrows C and D. The base drum 4 also has arrow C,
It moves up and down like D. A through hole 17 is provided in the gripper 1, and the hollow portion 4C of the base drum communicates with a pressure control mechanism 40, which will be described later, via an open lower portion, the through hole 17, and a tube 27. The pressure control mechanism 40 has the function of maintaining 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 next.

First, from the state shown in FIG. 1 (al), the base drum 4 is immersed in the coating liquid 1 as shown by the arrow C, and is brought into the state B shown by the - dotted chain line (the state shown in FIG. 1 (C)). The inner diameter of the hollow part 4c is made slightly larger than the outer diameter of the convex part 3, so that the inner circumferential surface 4d of the base drum 4 and the outer circumferential 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 air in the hollow part 4C is removed by the convex part 3, and the coating liquid 1
, the pressure inside the hollow portion 4C increases. The contact differential pressure gauge (PC) 36 has been modified in advance to perform analog control, and the hollow part 4C
When the internal pressure increases, a signal is sent to relay (RA) 37A, which opens solenoid valve 38A and leads tube 27 to the open system. Therefore, the air corresponding to the increased pressure in the hollow part 4C is discharged into the open system through the tube 27 as shown by the arrow Al-A2-A3, and the pressure in the hollow part 4C is linearly controlled.

When the immersion of the base drum 4 is completed, the pressure in the hollow part 4C is linearly controlled, so that the coating liquid level is at the position 1c.
At the same time, it 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 to the state shown by the solid line in FIG. Pressure decreases.When the pressure inside the hollow part 4c decreases,
A signal is sent from the contact differential pressure gauge to the relay (R'') 37B, the solenoid valve 38B opens, and the tube 27 is connected to the pressure pump (
Leads to P')39. Therefore, from the pressure pump 39,
As shown by the arrow B5-132-81, the air flows into the hollow part 4C.
The pressure inside the hollow portion 4C is thereby linearly changed.

When the lifting of the base drum 4 is completed, 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.

The pressure is controlled by a differential pressure gauge with contacts, but specifically,
For example, when immersing the base drum, the pressure should be changed from 0mmAq to 30mmAq.
The pressure can be changed linearly from 0 to 500mmAq, and the pressure can be changed from 300 to 50mmAq when lifting the base drum.
It can be linearly changed from 0ma+Aq to 0IIlffiAq. In this case, the lower limit is OmmAq
The upper limit value is set to 300 to 500 nv+Aq. Of course, both the upper limit value and the lower limit value should be adjusted depending on the specific gravity of the coating liquid 1, the solvent, the vertical length of the base drum 4, etc., and the above range cannot necessarily be determined uniformly. . The above upper limit contact and lower limit contact are connected to the base drum 4 when the specific gravity of the coating liquid l is about 1.
This applies when the length in the vertical direction is approximately 250 to 400 mm.

According to such a coating device, even when the base drum 4 is immersed, the coating liquid level rises only slightly from the height Zta, and the vertical movement of the coating liquid level due to the immersion and lifting of the base drum 4 does not occur. Very little. Therefore, the coating tank side wall inner peripheral surface 2b
As a result, the frequency of occurrence of foreign matter defects can be significantly reduced, and compositional changes and deterioration of the coating liquid 1 can also be suppressed. Therefore, coating productivity can be improved, waste of raw materials can be prevented, and costs can be reduced.

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, conventionally, as shown in FIG. 12, the rise in the coating liquid level due to the immersion of the base drum 4 was as large as 12, and this rise in the coating liquid level from position 1b to position 1a caused a predetermined rise in the coating liquid level. It was possible to coat the outer circumferential surface 4e of the base drum up to position 4a.

In other words, assuming that the coating liquid level does not rise as described above when the base drum 4 is immersed, it is impossible to perform the desired coating 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. Even if the base drum 4 is immersed as shown in FIG. 1 (C1), 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.
Until 2. rise greatly. Therefore, in this state, the first
When the base drum 4 is immersed into the coating liquid 1 as shown in Figure (C1), the desired coating can be carried out to the desired height of the predetermined position 4a at the same time while suppressing the vertical movement of the coating liquid level 1a as described above. .

Moreover, when the base drum 4 is immersed and pulled up, the pressure control mechanism 40 described above allows the base drum hollow portion 4c to
The pressure inside is made to change linearly. 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 the position IC shown in C). Therefore, it is possible to prevent the coating liquid from being applied or attached to the inner circumferential surface 4d of the base drum.

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 (Ji) from the inner circumferential surface 4d, and the coating liquid 1 would also be wasted, increasing the cost of materials, etc. This is inconvenient because it also increases.

On the other hand, if the air in the hollow portion 4C were to leak into the coating liquid 1, coating defects would occur, which would be inconvenient.

According to the present invention, both of these problems are technically solved, and the pressure control means 40 prevents the coating liquid 1 from entering the hollow portion 4C of the base drum, thereby reducing the troublesome operation as described above. This eliminates the need for the coating liquid 1, prevents wastage of the coating liquid 1, lowers the cost of materials, etc., and prevents coating defects due to air leaks.

As described above, according to the coating device of this example, it is possible to suppress vertical movement of the coating liquid level due to immersion and lifting of the substrate drum, reduce the amount of coating liquid required, and reduce the amount of coating liquid required to coat the inner circumferential surface of the substrate drum. It is also possible to prevent the coating liquid from being applied or attached to the surface.

Figure 2 shows another coating device, in which (a) is a schematic partial cross-sectional view, (bl is a cross-sectional view showing the coating tank, and (C) is a cross-sectional view showing the state in which the base drum is immersed. It is a diagram.

In the coating apparatus shown in FIG. 2, a convex portion 3 is provided on the bottom inner wall 2a of the coating tank 2, and a pressure control mechanism 40 is provided for controlling the pressure inside the base drum hollow portion 4c. , is a remarkable feature.

Note that, except for the above-mentioned points, the coating device shown in FIG.
It 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 not shown (see Figures 6 to 8). The same applies to equipment.)

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 made slightly larger than the outer diameter of the convex part 3, so that the false peripheral surface 4d of the base drum 4 and the outer peripheral surface 3b of the convex part 3 do not come into contact when the base drum 4 is immersed. It has become. 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 linearly changed.

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 falls to the level of the position IC. 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 lifting of the base drum 4 progresses, 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 is made to change linearly.

When the lifting of the base drum 4 is completed, 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 a predetermined height f4a.

The mode of control of the contact-equipped differential pressure gauge (PG) 36 is the same as that shown in FIG.

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 dried matter is generated on the inner circumferential surface 2b of the side wall of the coating tank, and the frequency of occurrence of foreign matter defects is significantly reduced. It is also possible to suppress component changes 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 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, it was necessary to fill the coating tank 2 and store a sufficient amount of coating liquid in the circulation system such as the tank 12. is required.

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 3, 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 is reduced, the amount of liquid in the circulation system is also reduced, and the overall amount of coating liquid required is significantly reduced. Accordingly, the pump can be made smaller by reducing the circulation amount (speed) of the coating liquid, and the filtration area of the filter can also be made smaller.

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 waste and replacement of the coating liquid is small, which is advantageous in that it prevents wastage of raw materials. It is.

Moreover, like the coating device shown in FIG. 1, the pressure control mechanism 40
Due to the function of the micro differential pressure gauge (PG) with a contact, the pressure inside the hollow part 4c is measured in advance even when the base drum 4 is immersed or pulled up.
36, thus preventing the coating liquid 1 from entering into the hollow portion 4c and preventing air from leaking into the coating liquid 1. 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, keeps material costs low, and eliminates coating defects caused by air leaks. It can also be prevented from occurring.

As described above, with the coating device of this example, it is possible to fully enjoy the advantages of the conventional overflow one-type method, reduce the amount of coating liquid required, and coat the inner circumferential surface of the base drum. It can also prevent liquid application and adhesion.

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

In this example, in Figure 0, in which the height of the convex portion 13 is higher than the liquid level position 1a, 13a is a hollow portion, and +3b is the outer peripheral surface of the 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) via an open lower part (see FIG. 2). These points also apply to the coating apparatuses shown in FIGS. 7 and 8.

In the example shown in FIG. 7, a cylindrical convex portion 23 having an opening 23c above is provided. The upper end of the convex portion 23 is higher than the liquid level position 1a.

In the example shown in FIG. 8, the open lower is provided on the bottom surface 2c of the coating tank.

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).

In addition, particularly when the present invention is applied to an overflow type coating device and applied to a coating liquid for forming a carrier generation layer, zero-grain carrier generation substances and carrier transport are considered to be particularly effective. This also applies to a single-layer photosensitive layer containing a 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.
This is because the effects of circulation include changes in viscosity and changes in the crystalline form of pigments. Therefore, if the coating apparatus of the present invention reduces the amount of coating liquid and the amount of circulation of the coating liquid, it is considered to be cost-effective.

FIGS. 9 to 11 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.
A carrier generation layer 3t is provided as a layer, and a carrier transport layer 32 is provided as a second layer on the carrier generation layer N31. The photoreceptor shown in FIG. 10 has a carrier transport layer 32 as a first layer and a carrier generation layer 31 as a second layer stacked in this order when viewed from the conductive substrate 30 side. 1st
The photoreceptor shown in FIG. 1 has a photosensitive layer 3 having a single layer structure containing both a carrier-generating substance and a carrier-transporting substance as the first N.
3.

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. 9 to 11, nor are their compositions, functions, etc. 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. 2N, the third layer is an undercoat layer, a carrier transport layer, and a carrier generation layer, the carrier generation layer, a carrier transport layer, and a protective layer, the first layer, the second layer, the third layer, the 4N Examples include those in which each of the layers is an undercoat layer, a carrier generation layer, a carrier transport layer, and a protective layer, or an undercoat layer, a carrier transport layer, a carrier generation layer, and a protective layer.

The undercoat layer can be made of acrylic, methacrylic, vinyl chloride, vinyl acetate, epoxy, polyurethane, phenol, polyester, alkyd, polycarbonate, silicone, melamine, vinyl chloride/vinyl acetate, etc. It can be formed from various resins such as polymers and vinyl chloride/vinyl acetate/maleic anhydride copolymers.

The carrier generation layer is made of, for example, a monoazo dye, a disazo dye,
Azo dyes such as trisazo dyes, perylene dyes such as perylene anhydride and perylene imide, indigo dyes such as indigo and thioindigo, polycyclic quinones such as anthraquinone, pyrenequinone and furapanthrones, quinacridone dyes, bis Generates various known carriers, such as benzimidazole dyes, induthrone dyes, squarelillium dyes, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, biryllium salt dyes, and eutectic complexes formed from thiapyrylium salt dyes and polycarbonate. The material can be formed by dissolving or dispersing the material in a solvent together with a suitable binder resin and, if necessary, a carrier transport material, and applying the solution.

The carrier transport layer is made of a polymer having a heterocyclic compound in its side chain, such as Bakapoly-N-vinylcarbazole, which is an electron-accepting substance that easily transports electrons, such as trinitrofluorenone or tetranitrofluorenone.
Various known compounds such as triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives, polyarylalkane derivatives, phenylenediamine Hg derivatives, hydrazone derivatives, amino-substituted chalcone derivatives, triarylamine derivatives, carbazole derivatives, stilbene derivatives, phenothiazine derivatives, etc. It can be formed by dissolving a carrier transport material that easily transports pores in a solvent together with a suitable binder resin, applying the solution, and drying it.

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.

Examples of the above seven inder resins include polycarbonate, polyester, methacrylic resin, acrylic resin,
polyvinyl chloride, polyvinylidene chloride, polystyrene,
Polyvinyl acetate, styrene copolymer resin (e.g. styrene-butadiene copolymer, styrene-methyl methacrylate copolymer), acrylonitrile copolymer resin (
For example, vinylidene chloride-acrylotolyl copolymer, etc.)
, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone, resin, silicone-alkyd resin, phenol resin (e.g. phenol-formaldehyde resin, m-talesol-formaldehyde m fat, etc.) , styrene-alkyd resin,
Film-forming polymers such as poly-N-vinylcarbazole, polyvinyl butyral, and polyvinyl formal are preferred.

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

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-) dichloroethane. ,1,1.2.2
-tetrachloroethane, 1,1.2-trichloropropane, 1°1.2.2-tetrachloropropane, 1,2.
3-trichloropropane, 1,1,2-trichlorobutane, 1,2,3,4-tetrachlorobutane, tetrahydrofuran, monochlorobenzene, dichlorobenzene, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate , dimethyl sulfoxide, methylcellosolve acetate, n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N.

Examples include N-dimethylformamide.

Further, as a solvent for dissolving the carrier transport substance and binder resin to form a coating solution, a solvent that can uniformly dissolve these is selected, but a solvent with a boiling point (b p) of 80
℃~150℃ is preferable, and 90℃~120℃ is more preferable. If the boiling point is less than 80℃, it dries too quickly and condenses, easily causing brushing, and also dries too quickly and leveling is not possible. , it is easy to become unable 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 (b p =83.5°C), 1.1.2-)dichloroethane (b p =113.5°C), 1,4-dioxane (b p =101 .3℃), benzene (b p
= 80.1°C), toluene (b p = 110.6°C),
Examples include o, m, p-xylene (bp -138 to 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, undercoat layer, etc., if present, is selected. In particular, among the above, toluene, chloroform, dichloromethane, 1,2-dichloroethane, 1゜1.2-)
Dichloroethane, 1,1.2.2-tetrachloroethane, tetrahydrofuran, monochlorobenzene, and dioxane are preferred solvents for both the carrier generation layer and the carrier transport layer.

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 siloxane compounds include dimethylpolysiloxane and methylphenylpolysiloxane.

The amount added is preferably 1 to 110,000 ppm, more preferably 10 to LOOOppm, 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, especially in the coating liquid for the carrier transport layer and the coating liquid for the carrier generation layer. In that case, the productivity and performance of the photoreceptor may be improved. This has the advantage of further improving the performance. That is,
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, memory characteristics, etc. will also be 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 paper or a plastic film 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 10 to 300 cp. preferable. If the viscosity is lower than the above range, the coating film tends to sag, and the film tends to be thicker at the bottom of the drum than at the top. If the viscosity is higher than the above range, the viscosity of the coating liquid in the coating tank tends to become uneven. , there is a tendency for film thickness unevenness to occur 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) and may not be able to exhibit sufficient carrier transport function.If it exceeds 50 μm, the charging ability is too high (more than 100 OV), the image quality tends to be rough, the resolution decreases, and the residual potential becomes large. easy. The amount of carrier transport material per 100 parts by weight of binder resin ranges from 20 to
The amount is preferably within the range of 200 parts by weight, preferably from 30 to 150 parts by weight. If it is less than 20 parts by weight, the carrier transport function will be low, sensitivity will decrease, residual potential will increase, and 2
If the amount exceeds 0.00 parts by weight, the viscosity and surface tension will be high and the 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 it is less than 0.05 μm, the carrier generation ability will be insufficient, and it will be difficult to apply it uniformly.
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 amount of the carrier-generating substance is less than 5 parts by weight, the carrier-generating ability is insufficient, and if it exceeds 500 parts by weight, carriers are trapped, and sensitivity decreases and memory generation is likely to occur. Further, the amount of the carrier transport substance to be included if necessary is preferably in the range of 20 to 200 parts by weight, preferably 30 to 150 parts by weight, per 100 parts by weight of the binder resin.

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 tends to increase and it becomes difficult to obtain sufficient transport ability.

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 undercoat 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. As a result, the volume of the convex portion becomes large enough to push up the liquid level of the coating liquid, and there is no possibility that the base drum and the convex portion come into contact with each other in some cases.

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.

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

Ki 1 no Xu ゛'s ill
, 2-dichloroethane (manufactured by Kanto Kagaku Co., Ltd.) (boiling point 83.5
5.0 g of polycarbonate (Panlite L-1250, manufactured by Kijin Kasei Co., Ltd.) as a binder resin was dissolved in 100 ml of Il. In addition, 10 g of 4,10-dibromoanthrone as a carrier-generating substance was ground in a ball mill for 24 hours, the above solution was added to this, and the solution was further dispersed in a ball mill for 24 hours, and a coating solution for forming a carrier-generating layer with a viscosity of 160 cp ( A dispersion liquid) was obtained.

Gear 1a fIkN 1.2-dichloroethane (manufactured by Kanto Kagaku Co., Ltd.) 10100
Polycarbonate resin (
100 g of Panrai IL-1250 (manufactured by Kijin Kasei Co., Ltd.) was dissolved, and 1゜1-bis (
4-N,N-dibenzylamino-2-methylphenyl)
A coating solution for forming a carrier transport layer was prepared by dissolving 100 g of normal butane.

<Coating experiment 1> 1 piece on a plate A coating experiment was conducted using the coating apparatus shown in FIG.

The diameter of coating tank 2 is 120III11, and the height is 350mm.
The diameter of the convex portion 3 was set to 75 mm+, and the height was set to 30 mm.

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 80ma + φX 35
A 0 mm aluminum cylindrical conductive substrate was used. In addition, a small differential pressure gauge with contacts (manufactured by Nagano Keiki), a solenoid valve, and a relay (manufactured by GK-DCORPORATION) were used. These are the same in Example 2 as well.

Using the coating tank shown in FIG. 12, 100 negatively charged photoreceptors were continuously manufactured under the same conditions as in Example 1.

However, the diameter of the coating tank is 8011Iffl, and the height is 350.
It was set as 01-.

Results of Coating Experiment 1> For the carrier generation layer on Huangfeng charcoal, the amount of coating liquid was 21 initially and the additional amount was 0.51, which required a total of 2.51.

Regarding the carrier transport layer, the coating liquid amount was 21 initially and an additional 1a, totaling 31.

Out of 100 photoconductors, 95 are good and the remaining 5 are good.
Coating defects (foreign object defects) were observed in the book.

The amounts of coating liquids for the carrier generation layer and the carrier transport layer on the stop plate were the same as in Examples.

Furthermore, out of 100 photoreceptors, 85 were good, and the remaining 15 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 the same, deterioration of the coating liquid is suppressed, the frequency of occurrence of coating defects is significantly reduced, and productivity is improved. It is clear that the results have improved.

Coating experiment 2> Real I [vomit] A coating experiment was conducted using the coating apparatus shown in FIG.

The diameter of coating tank 2 is 24011I11, and the height is 350ma.
+, the diameter of the convex portion 3 was 19011II11, and the height was 300+an+.

The above-mentioned coating liquid for forming a carrier generation layer and coating liquid for forming a carrier transporting layer are respectively stored in a coating tank, and a carrier generating layer and a carrier transporting layer are sequentially coated onto a base drum to form a negatively charged electrophotographic image. 100 photoreceptors were manufactured continuously. However, the base drum is 200mm φX 35
A 0 mm aluminum cylindrical conductive substrate was used.

Stop comparison test 1 Using the coating tank shown in FIG. 13, 100 negatively charged photoreceptors were continuously produced under the same conditions as in the examples. However, the diameter of the coating tank was 240 mm, and the height was 350 mm.

Results of Coating Experiment 2> Execution ±1 Regarding the carrier generation layer, the amount of coating liquid was initially 101 (61 for the coating tank, 41 for the piping), and an additional 11, for a total of 111.

Regarding the carrier transport layer, the amount of coating liquid was initially 1°l (61 in the coating tank and 41 in the piping), and an additional 21, for a total of 121.

Out of 100 photoreceptors, 98 were good.

For the carrier generation layer, the amount of coating liquid was initially 221 (1611 in the coating tank and 61 in the piping), and the additional amount was 11, for a total of 23 f.
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, 98 were good.

<Coating device> In addition, the capacity of the pump is ff1201 /win (
The size could be reduced from Comparative Example 2) to 2f/ll1in (Example 2). In addition, the filtration area of the filter was increased to 1300
0 cd (Comparative Example 2) to 1300 aa (Example 2)
).

As described above, it is clear that according to the coating apparatus of the example, 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 exemplified above, the embodiments of the present invention are not limited to the above embodiments (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.

Further, the means for sensing and detecting the pressure in the hollow portion of the base drum may be other than a differential pressure gauge with a contact point, and it is sufficient that the pressure change can be detected by some means and can be output as a signal. In addition, various means may be used to switch the connection with the hollow part of the base drum between a pressurizing pump system and an open system.
In short, any device that can perform the switching operation upon receiving the above signal is sufficient.

The pressure control means as a whole is not limited to the above.

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, significantly reducing the frequency of occurrence of foreign substance defects, and 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 within the recess of the object to be coated, when the object to be coated is immersed or pulled up, the pressure within the recess is controlled to prevent the coating liquid from entering the recess. Air in the recess can be prevented 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. .

[Brief explanation of the drawing]

1 to 8 show embodiments of the present invention, FIG. 1 shows a coating device, FIG. 1A is a schematic partial sectional view showing the coating device, and FIG. A cross-sectional view showing the tank, (C) a cross-sectional view showing the base drum immersed in the coating liquid, Fig. 2 showing another coating device, and (a) a schematic partial cross-section showing the coating device. Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 3, Fig. 4, Fig. 5, Fig. 6; , FIG. 7, and FIG. 8 are sectional views showing still other coating devices. FIG. 9, FIG. 10, and FIG. 11 are sectional views each showing an example of an electrophotographic photoreceptor. FIGS. 12 and 13 are cross-sectional views showing conventional coating devices, respectively. In addition, in the symbols shown in the drawings, t------------- Coating liquid 1a, 1b, 1 c----- Coating liquid level position 2.- ---1---------・Coating tank 2 d
−−1−−−−−−−−Coating tank side wall 2e・−1−
−−−−−−−−−・Green part on the side wall of the coating tank 3.13.2
3----------Convex portions 3a, 13a
-・-------1.Hollow part 3b, 13b, 23b-
・−−−−−−−−−−・Convex part outer peripheral surface 4−−−−−−
--------1.Base drum 4a~---1------
--- Predetermined position 4C --- ---------- Hollow part 4 d --- One --- Inner circumferential surface of base drum 7 --- −−・−−−−One opening 9−・−・−・
-・Dry substance 23 a------------One space 27・-
・-1~---------Tube 36---111-----Poor differential pressure gauge with contact (PG) 37A, 37B.--
-----1-・-1---Relay (RA, R") 38
A, 38 B------------- Solenoid valve 3 B-----------・Pressure pump (
P') βl ---m=・- Size β of rise in liquid level due to convex portion! ------・It is the magnitude of the vertical movement of the liquid level due to immersion. Agent: Hiroshi Aisaka, Patent Attorney Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 12 Figure 13 (Voluntary) Child material ε Ne T'4T Masculinity: Month C 1986 υ Day 1, Indication of the case 1986 Patent Application No. 286375'2, Name of the invention Coating device 3, Person making the amendment Relationship to the case Patent applicant address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name name
(127) Konica Co., Ltd. 4, agent address: FINE Building fl, 2-4-11 Shibasaki-cho, Tachikawa-shi, Tokyo 0425-24-5411■ (1) "Coating" on page 22, line 8 of the specification was changed to " I corrected it to ``application device''. −1 or more

Claims (1)

[Claims] 1. In a coating device that applies the coating liquid to the object by immersing an 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, configured so that the convex portion is inserted into the concave portion when the object to be coated is immersed, and is provided with pressure control means for controlling the pressure within the concave portion. A coating device featuring: