JPH0473776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for manufacturing an electrophotographic photoreceptor by applying a photosensitive material coating onto a substrate.
In particular, the present invention relates to an electrophotographic photoreceptor manufacturing apparatus that can efficiently apply a dispersed photoreceptor coating in which a pigment is dispersed in a resin solution and can obtain a photoreceptor coating film with good properties.

Electrophotographic photoreceptors basically have a structure in which a photosensitive layer is formed on a conductive substrate. The photosensitive layer is generally made by vapor-depositing selenium, but the manufacturing cost is high and the productivity is not good. As a method for forming a photosensitive layer, a method of applying a photosensitive material coating onto a substrate is very advantageous in terms of cost, productivity, yield, and applicability to a wide variety of substrate shapes.

As a photosensitive layer produced by coating, one in which dye-sensitized powder of zinc oxide or cadmium sulfide is dispersed in a binder resin is known. These use inorganic photosensitive materials, but as organic photosensitive materials, polyvinylcarbazole, trinitrofluorene, phthalocyanine, pyrazoline oxadiazole, etc. are mixed with a binder as necessary.
Or dispersed ones are known. Furthermore, functionally separated photosensitive layers in which a charge generation layer and a charge transport layer are stacked are also known in order to increase sensitivity, improve repeatability, and improve durability. The charge generation layer may contain azo pigments such as Sudan Red, Diane Blue, and Jenas Green B, quinone pigments such as Algol Yellow, Pyrene Quinone, and Indanthrene Brilliant Violet RRP, quinocyanine pigments,
Indigo pigments such as perylene pigments, indigo and thioindigo, bisbenzimidazole pigments such as India First Orange toner, phthalocyanine pigments such as copper phthalocyanine, charge-generating substances such as quinacridine pigments, polyester, polystyrene, polyvinyl butyral, polyvinylpyrrolidone, etc. It is formed by being dispersed in a binder resin such as methyl cellulose, polyacrylic esters, and cellulose esters. Its thickness is about 0.01 to 1μ, preferably about 0.05 to 0.5μ. In addition, the charge transport layer contains a polycyclic aromatic compound such as anthracene, pyrene, phenanthrene, coronene, etc. in the main chain or side chain, or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole. It is formed by dissolving a hole-transporting substance such as a compound having a nitrogen-containing cyclic compound such as , triazole, or a hydrazone compound in a resin that has film-forming properties. This is because the charge transporting substance generally has a low molecular weight and has poor film-forming properties by itself. Examples of such resins include polycarbonates, polymethacrylates, polyarylates, polystyrene, polyesters, polysulfones, styrene-acrylonitrile copolymers, styrene-methyl methacrylate copolymers, and the like. The thickness of the charge transport layer is 5 to 20 microns.

Further, as the conductive substrate used in the present invention,
Used are aluminum, brass, stainless steel, etc. formed into cylinders or foils, and paper, plastic, etc. on which aluminum, tin oxide, antimony oxide, indium oxide, etc. are vapor-deposited or laminated. In addition, as a method for forming the conductive layer, metal powder such as aluminum, silver, gold, nickel, copper, carbon powder, tin oxide, antimony oxide, etc.
There is also a method of applying a conductive paint in which a conductive coating material such as indium oxide is dispersed in a resin.

The above has described electrophotographic photoreceptors manufactured by coating, but coating methods include spraying, roll coating, bar coating, knife coating,
There are various methods such as screen coating and dipping. Among these coating methods, the dip coating method is extremely advantageous for seamlessly coating a cylindrical substrate such as an electrophotographic photoreceptor by dipping the substrate into the coating and pulling it up. .

In such a dip coating method, in the case of a dispersed photosensitive material paint in which pigments are dispersed in a solution, the specific gravity of the pigment is generally large, so that the pigment tends to settle or accumulate in the paint. Therefore, uneven concentration and composition of the paint occur, which tends to cause unevenness in the paint film. As a countermeasure against this, it is desirable to put the photosensitive material paint in which the pigment has been dispersed into the coating tank for dipping as soon as possible. Furthermore, it is preferable to keep the paint in constant motion so that the pigments do not settle.

There are various methods for dispersing pigments, such as ball mills, roll mills, sand mills, attritor mills, and colloid mills.
The sand mill method is very advantageous in these respects. Since the sand mill method has the advantage of being able to continuously disperse pigments from rough dispersion to finishing, it is disadvantageous from the standpoint of sedimentation to store the paint after dispersion in a container. Also, it takes a lot of effort,
It also causes an increase in process steps.

The first feature of the present invention is that the sand mill device and the coating tank for dip coating are integrally connected, and the process from inputting raw materials to coating is performed continuously. According to the present invention, if the pigment and the resin solution used as a binder are put into the sand mill device when the paint is needed, the dispersed paint is sent to the coating tank, so the steps in between can be omitted and sedimentation can be avoided. It can be less.
In particular, when electrophotographic photoreceptors are manufactured by coating, it is desired to automate the process in order to prevent dust and particles from forming in the coating film, and the present invention is highly effective.

An example of a sand mill apparatus for dispersing pigments is shown in FIG. The inside of the container (vessel) 1 is filled with small particles made of materials such as alumina, zirconia, stainless steel, glass, sand, iron, etc. as a dispersion medium. The paint raw material is supplied from the input port 2. A plurality of impellers 3 attached to a rotating shaft 4 are provided inside the container, and the impellers 3 rotate at high speed to agitate the pigment and resin solution in the container. The rotation speed is 200-4000 rpm. The dispersed paint is separated from the dispersion medium through a mesh or grid 5 and emerges from an outlet 6. Such a sand mill device may be used alone, or if dispersion is insufficient, a plurality of sand mill devices may be connected.

Although the paint that comes out of the sand mill equipment passes through the gap, it still contains crushed dispersion medium and undispersed coarse particles.
It is difficult to use when a highly smooth coating surface is required, such as electrophotographic photoreceptors. Therefore, the present invention provides a second method in which a filter for filtering paint after sand milling is integrally connected to the sand mill device.
The characteristics of

The filter may have a mesh that does not allow coarse particles to pass through the film, preferably one that is finer than the film thickness and larger than the pigment particles. In addition, it is more effective to reduce clogging by arranging a filter in series with a large-mesh filter to capture coarse particles and a fine-mesh filter to capture fine particles that cause dirt. .

The paint that has passed through the filter is sent to the coating tank. The third feature of the present invention is that in order to agitate the paint in the coating tank and to keep the surface of the paint always fresh, the paint is constantly overflowing from the top of the coating tank, and the overflowing paint is recycled again. It passes through a filter and is circulated and supplied to the coating tank.

A pump is connected to circulate the liquid in this way and to supply the sand mill equipment with the paint before dispersion. As the pump, any pump such as a magnetic pump, gear pump, diaphragm pump, screw pump, etc. may be used.

That is, the apparatus for manufacturing an electrophotographic photoreceptor according to the present invention is an apparatus for manufacturing an electrophotographic photoreceptor by coating a photosensitive material paint in which pigments are dispersed onto a substrate by a dip coating method, and includes a sand mill device for dispersing pigments. , a paint tank to store the paint dispersed by the sand mill device and paint overflowing from the top of the coating tank, a filter to filter the paint in the paint tank and supply it to the coating tank, and a filter to transfer the filtered paint onto the substrate. The present invention is characterized in that a coating tank for dip coating is continuously integrated with the coating tank.

Hereinafter, one embodiment of the apparatus of the present invention will be described with reference to FIG.

The paint 11 before being dispersed is placed in a front tank 12, to which a stirrer 13 is attached. The paint is pumped by a pump 14 and sent to a sand mill device 15. In the illustrated embodiment, a two-barreled sand mill apparatus is shown, each having a structure as shown in FIG. The dispersed paint 41 is stored in a paint tank 40, then pressurized by a pump 43, passes through a filter 17, and is sent to a coating tank 44. 18 indicates a valve.

The paint 46 that is continuously sent to the coating tank overflows from the top of the coating tank (overflow) and is deposited in the receiving tray 4.
5, is returned to the coating tank 40, and is again circulated and supplied to the coating tank through the filter 17. The coating tank has a lid 47 to reduce evaporation of the solvent during overflow.

A base 30 of the electrophotographic photosensitive member is attached to an elevating member 32 by a holding member 31, which is moved up and down by rotation of an elevating motor 34 and a screw screw 33.

As described above, the electrophotographic photoreceptor manufacturing apparatus according to the present invention includes a sand mill device 15 for dispersing pigment, a filter 17 for filtering the dispersed paint, and a coating tank for dip-coating the paint onto the substrate. 44, and the dispersed paint is supplied to the coating tank 44 through the filter 17 before the paint surface dries, the pigment reagglomerates, the viscosity increases, or gels. and coating tank 4
The paint overflowing from the upper part of the coating tank 4 passes through the filter 17 again and is circulated and supplied to the coating tank 44.

As described above, the electrophotographic photoreceptor manufacturing apparatus according to the present invention, in which a sand mill dispersion device, a filter, and a coating tank are integrally connected, can shorten the process and prevent pigment sedimentation when coating a pigment dispersion type paint. It is very effective in preventing reagglomeration and reducing solvent evaporation. It is also possible to prevent accidents such as paint stains and scattering during the process.

Furthermore, the device of the invention is very effective, especially when the dispersion coating is thixotropic.
If the paint is thixotropic, the viscosity of the paint will vary depending on the fluidity of the paint, and when the paint is allowed to stand still, the viscosity will gradually increase, and eventually it will gel and lose its fluidity. In order to prevent this, it is possible to constantly stir the paint or apply dynamic stimulation from the outside, but once the paint after being dispersed is taken out from the disperser, it is time-consuming. However, unlike the present invention, without taking the paint outside,
If data is sent continuously, there is no need to worry about this.

Furthermore, since the paint overflows from the top of the coating tank and the overflowing liquid is passed through the filter again and supplied to the coating tank, it is also effective in removing particles that have aggregated or precipitated in the coating tank.

In addition, in the device of the present invention, the dispersion of the paint is
It is not necessary to do this all the time, and it is sufficient to just compensate for the loss caused by application. An operator may confirm that the amount of paint has decreased each time and operate the sand mill dispersion machine, but it is more preferable to use automation. To do this, a mechanism for detecting the amount may be attached to the paint tank 40, so that when the amount decreases below a certain level, the dispersed paint is supplied, and when the amount is filled, the dispersion is stopped. Examples of mechanisms for detecting the amount of paint include a method using a float and a method of optically detecting the liquid level.

Hereinafter, an example in which an electrophotographic photoreceptor was manufactured using the electrophotographic photoreceptor manufacturing apparatus shown in FIG. 2 will be described.

Example 1 shows the step of forming a subbing layer on the substrate of an electrophotographic photoreceptor using the apparatus shown in FIG. 2 shows the step of forming a photosensitive layer on the .

Example 1 In an electrophotographic photoreceptor manufacturing apparatus as shown in FIG. 2, the internal volume of the sand mill device 15 is 2.8.
And so. The interior is shown in Figure 1, and the blades used were made up of eight blades. The space was filled with glass beads (manufactured by Toshiba Glass) having an average diameter of 1 mm. The rotation speed of the blade was 2000 rpm. The number of stages in the sand mill is two as shown in Fig. 2, and the pump 14 is equipped with a
A 100ml/min diaphragm pump was used. The capacity of the front tank 12 was 5, and a homogenizer (manufactured by Yamato Kagaku) was attached to it to enable pre-dispersion.

The capacity of the paint tank 40 was 5, and a rotary agitator (manufactured by Shinsha Kagaku) was attached to it. Pump 43 is a diaphragm pump with a flow rate of 1/min. Filter 17 was a 25μ filter (manufactured by Toyo Paper Co., Ltd., trade name: Tocel TCW-25RS) installed in the housing.

The coating tank 44 has a cylindrical shape with an inner diameter of 80 mm and a height of 350 mm, and a saucer 45 is attached to the top to catch overflowing paint.
I connected the piping so that the paint could return to.

The base 30 of the electrophotographic photoreceptor has an outer diameter of 60 mm and a height
A 260mm aluminum cylinder with a closed top and an open bottom was used. This is achieved by a variable speed motor (Fuji Electric PS motor).
be raised and lowered.

The paint was dispersed and applied using the electrophotographic photoreceptor manufacturing apparatus in which the sand mill device, filter, and coating tank were integrated as described above. First of all, the special request was made in 1983.
A conductive smooth layer as shown in No. 195062 was formed. Titanium oxide powder (manufactured by Sakai Chemical) 10 parts (parts by weight,
(The same applies below) 5 parts of tin oxide powder (manufactured by Mitsubishi Metals), 15 parts of one-component epoxy resin (solid content concentration 50%, manufactured by Amicon), and 30 parts of toluene were weighed and put into the front tank of the manufacturing equipment. . 10 in homogenizer
After stirring for more than a minute, the mixture was pumped to a sand mill device. After 15 minutes, the first stage sand mill device was rotated, and after a further 15 minutes, the second stage was rotated.
Continuous operation was carried out in this condition, but the paint that came out during the first 30 minutes was returned to the front tank.

After the dispersed paint had accumulated to some extent in the paint tank, it was pumped into the coating tank. When paint began to overflow from the coating tank and was accumulated in the paint tank, the sand mill equipment and pump were stopped. After that, the dispersion process is
This is to be done when the paint is running low.

After the substrate was immersed in the coating tank, it was pulled up at a speed of 180 mm/min. After air drying for 5 minutes, it was cured at 170°C for 30 minutes. In this way, an undercoat layer with a thickness of 15 μm was formed. This layer is provided to cover scratches and irregularities on the surface of the substrate.

Example 2 Polyamide resin (trade name: Amilan) was applied onto the undercoat layer formed in Example 1 using another coating device.
A 4% methanol solution (CM8000, manufactured by Toray Industries, Ltd.) was applied to form a 0.5μ thick resin layer. This is to improve the charge injection properties of the photosensitive layer to be formed next.

An electrophotographic photoreceptor manufacturing apparatus as shown in FIG. 2 was used. However, at this stage, the sand mill device was a four-stage continuous type. The flow rate of the pump 14 was 50 ml/min. The filter was a 25μ filter, and then a 5μ filter (Tocel TCW-5RS manufactured by Toyo Paper Co., Ltd.) was connected to make two filters.
A solvent dripper was attached to the paint tank 40.

Next, add 10 parts of the disazo pigment with the following structural formula. Cellulose acetate butyrate resin (product name: CAB-381:
(manufactured by Eastman Chemical) and 60 parts of cyclohexanone were weighed out, mixed well, and then charged into the front tank. After stirring with a homogenizer for more than 15 minutes, the pump was activated to begin pressure feeding. The sand mill apparatus was rotated one stage every 30 minutes. After all four stages were rotated to achieve continuous operation, the paint that came out was returned to its original front tank for the first hour. After that, the paint that came out was stored in the paint tank, and at this time, methyl ethyl ketone was dropped in an amount equal to the volume of the paint that came out.

When enough paint accumulated in the coating tank and overflowed to allow sufficient liquid circulation, the disperser was stopped, and from then on, when the amount of paint decreased, it would be dispersed.

The substrate provided with the polyamide resin layer was immersed in this coating bath and pulled up at a speed of 160 mm/min. 60℃
was dried for 10 minutes to form a charge generation layer with a thickness of 0.1μ.

Although the disazo pigment used here tends to re-agglomerate even after being dispersed, it was possible to apply it efficiently by using the apparatus according to the present invention.

Next, add 10 parts of a hydrazone compound having the following structural formula. and 20 parts of styrene-methyl methacrylate copolymer resin (trade name: MS-200, manufactured by Nippon Steel Chemical) were dissolved in 90 parts of toluene. This liquid was coated on the charge generation layer using a separate coating device and dried at 100° C. for 1 hour to form a charge transport layer with a thickness of 16 μm.

An electrophotographic photoreceptor was manufactured as described above.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a sand mill device used in the device of the present invention, and FIG. 2 is a schematic diagram showing one embodiment of the device of the present invention. 1...Sand mill device container (Bethcel), 2
...Input port, 3...Impeller, 4...
Rotating shaft, 5...Gap, 6...Exit, 11...
Paint before dispersion, 12... Front tank, 13... Stirrer, 14... Pump, 15... Sand mill device,
16...Motor, 17...Filter, 18...
Bulb, 30... Substrate of electrophotographic photoreceptor, 31...
...Holding member, 32... Lifting member, 33... Screw screw, 34... Lifting motor, 40... Paint tank, 41... Paint after dispersion, 43... Pump,
44...application tank, 45...saucer, 46...paint.

Claims (1)

[Scope of Claims] 1. In an apparatus for manufacturing an electrophotographic photoreceptor by coating a photosensitive material paint in which a pigment is dispersed onto a substrate by a dip coating method, there is provided a sand mill device for dispersing the pigment; A paint tank that stores the applied paint and the paint that overflows from the top of the application tank.
An electronic photograph characterized in that a filter for filtering the paint in the paint tank and supplying it to the coating tank, and a coating tank for applying the filtered paint onto a substrate by dip coating are continuously integrated. Photoconductor manufacturing equipment. 2 Add a mechanism to detect the amount of paint in the paint tank,
2. The apparatus for manufacturing an electrophotographic photoreceptor according to claim 1, wherein when the amount of paint decreases below a certain amount, a sand mill device is driven to supply the paint.