JP2007225867A - Coating film formation device of electrophotographic photoreceptor and coating film formation method thereof, electrophotographic photoreceptor, image forming method and image forming apparatus using the same, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating film formation device of electrophotographic photoreceptor capable of forming a coating film free from coating irregularity and cissing even when performing a dip coating while circulating coating liquid, to provide a coating film formation method of an electrophotographic photoreceptor, to provide the electrophotographic photoreceptor formed by the coating film formation method thereof, and to provide an image forming apparatus comprising the electrophotographic photoreceptor. <P>SOLUTION: By using the coating film formation device provided with: a coating vessel 2 for performing dip coating of a conductive base body 1; a coating liquid tank 3 which stores coating liquid and is provided with a stirring means 5 and a cooling means 4; and a moisture adsorption tank 7 which is provided with a cooling means 8 and stores a moisture adsorbent 9, the coating liquid in the coating vessel is kept at 15°C or less by the cooling means of the coating liquid tank and moisture in the coating liquid is removed without temperature rising by the moisture adsorption tank while continuously circulating the coating liquid, a coating film is formed on the conductive base body 1 by the dip coating and the coating film is dried to prepare a photoreceptor layer comprising a pigment containing layer. The image forming apparatus is constituted by using the electrophotographic photoreceptor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating film forming apparatus and a coating film forming method for an electrophotographic photosensitive member, and more specifically, a coating film that forms a coating film by dipping and applying a coating liquid containing a pigment to a substrate for an electrophotographic photosensitive member. The present invention relates to a forming apparatus, a coating film forming method using the coating film forming apparatus, an electrophotographic photosensitive member obtained by the coating film forming method, an image forming method using the same, an image forming apparatus, and a process cartridge.

  An electrophotographic photosensitive member is generally manufactured by applying a photosensitive material to a peripheral surface of a drum-shaped electrophotographic photosensitive member substrate (hereinafter referred to as “photosensitive member substrate”). As a method for applying the photosensitive material on the photosensitive substrate, the photosensitive substrate is usually applied while relatively moving the photosensitive tank and the coating tank containing the photosensitive material and the photosensitive substrate. There is known a dip coating method in which a coating film is formed after being dipped in and pulled up.

  As a coating apparatus used for such a dip coating method, a coating tank for immersing a photoreceptor substrate and a coating liquid tank for storing a coating liquid are connected by a pipe, and a coating tank in the coating liquid tank is connected. A device is known that transports the working liquid by a pump, supplies the coating liquid into the coating tank from the lower part of the coating tank, and returns the circulating coating liquid from the upper part of the coating tank to the coating liquid tank for circulation. .

However, in the case of dip coating using the coating apparatus having the above-described configuration, the viscosity of the pigment-dispersed coating liquid increases with time, and the thixotropy inherent to it is further enhanced. Since non-uniformity occurs, the coating film to be dip coated is non-uniform and uneven coating tends to occur.
For example, in the case of a coating liquid in which a disazo pigment is dispersed, if the circulation period of the coating liquid is long, the viscosity of the coating liquid increases, and coating unevenness occurs. For this reason, when an electrophotographic photosensitive member provided with a disazo pigment-containing layer on a photosensitive substrate is mounted on a copying machine, it appears as a density unevenness image particularly in a halftone image at a halftone potential.
In addition, an organic solvent is used for the coating solution, and the moisture content in the coating solution increases with time by repeating the circulation of the coating solution. The property changes and a film defect due to repelling occurs.

As a countermeasure against coating unevenness due to an increase in the viscosity of the coating solution, a manufacturing apparatus has been proposed in which a stirring plate having a single hole only in the central portion is moved up and down in the immersion tank (for example, a patent) Reference 1). Or the manufacturing method which controls the flow of the coating liquid of the vicinity of a to-be-coated object when immersing a to-be-coated object in a coating liquid is proposed (for example, refer patent document 2).
However, each of the above proposals has a problem that it is difficult to obtain the effect when the coating solution viscosity increases.

In addition, an electrophotographic coating apparatus using a dehydrating filter has been proposed as a method for removing moisture in the coating liquid (see, for example, Patent Document 3).
According to this proposal, there is a certain effect with respect to the removal of moisture, but there is a problem that the increase in the liquid viscosity cannot be suppressed and the stability of the coating liquid over time cannot be achieved. In addition, there is a problem that the coating liquid temperature fluctuates when the moisture adsorbent is attached / detached, and as a result, coating unevenness occurs, resulting in inferior continuous productivity.

Note that the present applicant has previously applied an electrophotographic photosensitive member coating apparatus (see, for example, Patent Document 4) or an adsorbent tank provided with a dehydrating filter for controlling the water content in the photosensitive member coating liquid. Alternatively, an electrophotographic photosensitive layer forming coating solution coating apparatus provided with a desiccant tank (for example, see Patent Document 5) has been proposed.
According to the proposed apparatus, an increase in moisture is suppressed and repelling and the like are improved. However, this is not sufficient for increasing the viscosity of the coating liquid over time, and improvement in the generation of density unevenness images is desired.

JP-A-3-20747 Japanese Patent Laid-Open No. 10-48849 Japanese Patent Laid-Open No. 7-248632 JP-A-8-24743 JP 2000-275871 A

  The present invention has been made in view of the above-described prior art, and a substrate for a photoreceptor (hereinafter referred to as “conductive substrate”) is dip-coated in a coating solution containing a pigment that is repeatedly circulated. Even without increasing the viscosity of the coating solution over time, and without increasing the water content in the coating solution, it is possible to form a uniform and stable coating without the occurrence of uneven coating or repellency. A coating film forming apparatus capable of being used, and a coating film forming method using the coating film forming apparatus, and an electrophotographic photosensitive member free from occurrence of abnormal images (density unevenness, white spots, etc.) obtained by the coating film forming method. An object is to provide a body, an image forming method using the body, an image forming apparatus, and a process cartridge for the image forming apparatus.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by the inventions described in the following (1) to (15), and have reached the present invention. Hereinafter, the present invention will be specifically described.

(1): A coating film forming apparatus for an electrophotographic photoreceptor, in which a conductive substrate is immersed in a coating solution containing at least a pigment, and a coating film is formed on the substrate to form a pigment-containing layer by post-processing drying. There,
The device is
A coating tank for dip-coating a coating liquid containing a pigment on a conductive substrate;
A coating liquid tank that contains a stirring means and a cooling means for containing a coating liquid containing the pigment;
A coating liquid supply pipe for supplying a coating liquid from the bottom of the coating liquid tank to the bottom of the coating tank;
A circulation pump and a circulation filter sequentially arranged from the coating liquid tank side in the path of the coating liquid supply pipe;
A return liquid transport pipe that is introduced from the bottom of the coating tank and returns the coating liquid overflowed from the top of the coating tank to the coating liquid tank;
A circulation transport pipe that branches between a circulation pump and a circulation filter in the coating liquid supply pipe and circulates a part of the coating liquid supplied from the bottom of the coating liquid tank to the upper part of the coating liquid tank through a valve; ,
Comprising a cooling means arranged in the path of the circulating transport pipe, and a moisture adsorption tank containing a moisture adsorbent;
With
The coating liquid containing the pigment supplied into the coating tank is maintained at a predetermined temperature by the cooling means of the coating liquid tank, and the moisture in the coating liquid is not increased by the moisture adsorption tank provided with the cooling means. An apparatus for forming a coating film on an electrophotographic photosensitive member, wherein the coating film is formed so as to be removed.

According to the apparatus configured as described above, the coating liquid temperature is controlled by the cooling means, and even if the coating liquid containing the pigment is repeatedly circulated, the viscosity of the coating liquid does not increase with the passage of time, and therefore thixotropy is also achieved. It is not strong and does not cause non-uniform viscosity. For this reason, there is no occurrence of coating unevenness. In addition, since the moisture in the coating liquid is adsorbed without increasing the temperature by the moisture adsorbent accommodated in the moisture adsorption tank provided with the cooling means, no repelling or the like occurs. As a result, a uniform and stable coating film can be formed.
Furthermore, since the coating operation can be repeated while continuously circulating the coating liquid, it is efficient and has good productivity, and there is little loss of the coating liquid.

  (2) The coating film forming apparatus for an electrophotographic photosensitive member according to (1), wherein a predetermined temperature of the coating solution supplied into the coating tank is 15 ° C. or lower.

  By maintaining the temperature of the coating liquid at 15 ° C. or lower, even if the coating liquid containing the pigment is repeatedly circulated, an increase in the viscosity of the coating liquid over time is suppressed, and the occurrence of uneven coating is surely prevented. it can. Therefore, when the coated film is dried to form a pigment-containing layer, the occurrence of abnormal images can be prevented.

  (3): The coating liquid inflow side to the moisture adsorption tank disposed in the path of the circulation transport pipe is a lower side of the moisture adsorption tank, and the coating solution outflow side is an upper side of the moisture adsorption tank. The apparatus for forming a coating film on an electrophotographic photosensitive member according to (1) or (2).

  With the above configuration, it is possible to prevent the moisture content from increasing while improving the efficiency of adsorption of moisture in the coating liquid and improving the cooling efficiency.

  (4) The electrophotographic photosensitive member according to any one of (1) to (3), wherein the moisture adsorbent is filled in an adsorbent-filled container that is exchangeably stored in a moisture adsorption tank. This is a body film forming apparatus.

  By filling the adsorbent filling container that is exchangeably stored in the moisture adsorption tank with the moisture adsorbent, the exchange of the moisture adsorbent is facilitated, and maintenance management is simplified. When replacing the moisture adsorbent, the temperature rise of the coating liquid can be suppressed by closing the valve and stopping the circulation of the coating liquid to the moisture adsorption tank.

  (5) The electrophotographic photoreceptor coating film forming apparatus according to (4), wherein the moisture adsorbent is a synthetic zeolite (molecular sieve).

  By using the molecular sieve as the moisture adsorbent, moisture in the coating liquid containing the pigment can be effectively adsorbed and an increase in the amount of moisture can be reliably suppressed.

  (6): The coating liquid inflow side and the coating liquid outflow side of the adsorbent filling container filled with the moisture adsorbent each have an opening of a mesh structure (4) or (5) The electrophotographic photoreceptor coating film forming apparatus described in 1.

  By using the mesh-structured opening, the inflow and outflow of the coating liquid to the adsorbent-filled container can be facilitated, and the filled water adsorbent can be held and circulated without reducing the flow rate.

  (7) The coating film forming apparatus for an electrophotographic photosensitive member according to (6), wherein an opening diameter in the opening of the mesh structure is 130 μm or less.

  By setting the opening diameter to 130 μm or less, the moisture adsorbent is reliably held, and the occurrence of coating unevenness is suppressed.

  (8) The coating film forming apparatus for an electrophotographic photosensitive member according to any one of (1) to (7), wherein the coating liquid containing the pigment is a dispersion containing a disazo pigment. .

  When a dispersion containing a disazo pigment is used, the increase in viscosity over time is suppressed, the thixotropy is not strengthened, a coating without uneven coating or repellency is formed, and the coated coating is dried. An electrophotographic photoreceptor having a pigment-containing layer is good without generating white spots.

(9): A coating film forming method for an electrophotographic photosensitive member, wherein a conductive substrate is immersed in a coating solution containing at least a pigment, and a coating film is formed on the substrate to form a pigment-containing layer by post-processing drying. There,
The method
Using the electrophotographic coating film forming apparatus according to any one of (1) to (8),
A coating liquid containing a pigment contained in a coating liquid tank having a stirring means and a cooling means and whose liquid temperature is controlled is circulated in a path from the bottom of the coating liquid tank to the bottom of the coating tank and circulated in the path. Supply the filter from the coating liquid tank side through the coating liquid supply pipe,
The coating liquid introduced from the bottom of the coating tank and overflowed from the top of the coating tank is returned to the coating liquid tank by a return liquid transport pipe,
In parallel, a part of the coating liquid supplied from the bottom of the coating liquid tank is branched between a circulation pump and a circulation filter of the coating liquid supply pipe, and the moisture adsorption tank provided with a cooling means is routed. Circulate to the upper part of the coating liquid tank through a valve with the deployed circulating transport pipe, and remove the water in the coating liquid without increasing the temperature in the moisture adsorption tank containing the moisture adsorbent in the circulation path.
An electrophotographic method comprising: dipping a conductive substrate in a temperature-controlled coating solution introduced into the coating tank; and then pulling the film to form a pigment-containing layer on the substrate by drying after treatment. This is a method for forming a coating film on a photoreceptor.

  According to the coating film forming method, even when the coating liquid containing a pigment is repeatedly circulated, the viscosity of the coating liquid does not increase with time, and there is no occurrence of coating unevenness due to viscosity nonuniformity. Further, the moisture in the coating liquid is adsorbed without increasing the temperature by the moisture adsorbent, and no repelling or the like occurs. As a result, there is little loss of the coating liquid, and a uniform and stable coating film can be formed efficiently, with good productivity.

(10): A pigment-containing product obtained by drying a coating film formed by dip-coating a conductive substrate in a coating solution containing at least a pigment by the coating film forming method for an electrophotographic photosensitive member according to (9) An electrophotographic photoreceptor having a layer comprising:
The electrophotographic photoreceptor, wherein the pigment-containing layer is a photosensitive layer containing a photoconductive pigment.

  As described above, a high-quality and highly reliable electrophotographic photosensitive member free from occurrence of abnormal images (density unevenness, white spots, etc.) can be obtained.

  (11) The electrophotographic photosensitive member according to (10), wherein the pigment-containing layer is a charge generation layer in a photosensitive layer having a laminated structure of a charge generation layer and a charge transport layer.

  The photosensitive layer has a function-separated structure consisting of a charge generation layer and a charge transport layer, thereby improving sensitivity and durability. By making the charge generation layer a pigment-containing layer, abnormal images (density unevenness, white spots, etc.) A high-quality and highly reliable electrophotographic photosensitive member without occurrence of) is obtained.

  (12) The electrophotographic photosensitive member according to (11), wherein the charge generation layer contains a disazo pigment.

  By containing a disazo pigment in the charge generation layer, an electrophotographic photoreceptor having high sensitivity and good charging characteristics can be obtained.

(13): An image forming method including steps of charging, exposing, developing and transferring an electrophotographic photosensitive member,
An electrophotographic photosensitive member according to any one of (10) to (12), wherein the electrophotographic photosensitive member is an image forming method.

Since the image forming method includes the electrophotographic photosensitive member according to any one of the above,
High-quality and highly reliable and stable image formation without occurrence of abnormal images such as density unevenness and white spots can be performed.

  (14) An image forming apparatus comprising at least a charging unit, an exposing unit, a developing unit, a transferring unit, and the electrophotographic photosensitive member according to any one of (10) to (12).

  According to the above configuration, since any one of the electrophotographic photosensitive members described above is provided, an image forming apparatus that can maintain high quality and reliability even during repeated use is provided.

  (15): At least the electrophotographic photosensitive member according to any one of claims 10 to 12 and at least one means selected from a charging means, an exposure means, a developing means, and a cleaning means are integrated. A process cartridge for an image forming apparatus.

  According to the above configuration, the apparatus can be reduced in size and maintainability can be improved, and high-quality, reliable and stable image formation can be achieved without occurrence of abnormal images such as uneven density and white spots even during repeated use. It can be carried out.

According to the coating film forming apparatus for an electrophotographic photosensitive member according to the present invention, even if the conductive substrate is dip coated while repeatedly circulating the coating liquid containing the pigment, the viscosity of the coating liquid increases and the coating is increased over time. Since there is no increase in the water content in the liquid, it is possible to form a uniform and stable coating film with no coating unevenness or repellency. If this film is dried and then dried, an electrophotographic photoreceptor having a pigment-containing layer on a conductive substrate can be obtained.
According to the method for forming a coating film on an electrophotographic photoreceptor according to the present invention, a reliable coating film having a uniform film thickness that does not cause coating unevenness or repellency over time can be reliably formed. In addition, the coating liquid can be formed efficiently and easily with little loss of coating liquid.
According to the electrophotographic photosensitive member of the present invention, it is possible to form a high-quality and high-reliability image without occurrence of density unevenness and abnormal images such as white spots in image formation by electrophotography. An electrophotographic photosensitive member with good photosensitivity can be obtained by making the photosensitive layer into a function-separated structure of the charge generation layer and the charge transport layer and containing the disazo pigment in the charge generation layer.
According to the image forming method of the present invention, abnormal images such as density unevenness and white spots are not generated, and a stable and clear image can always be formed.
According to the image forming apparatus and the process cartridge for the image forming apparatus according to the present invention, even when used for a long time, the photosensitivity and charging characteristics are maintained well, no abnormal image is generated, and high quality and reliability are maintained. An image can be formed.

As described above, the electrophotographic photoreceptor coating film forming apparatus in the present invention is a coating film in which a conductive substrate is immersed in a coating solution containing at least a pigment, and a pigment-containing layer is formed on the substrate by drying after treatment. An electrophotographic photoreceptor coating film forming apparatus for forming
The device is
A coating tank for dip-coating a coating liquid containing a pigment on a conductive substrate;
A coating liquid tank that contains a stirring means and a cooling means for containing a coating liquid containing the pigment;
A coating liquid supply pipe for supplying a coating liquid from the bottom of the coating liquid tank to the bottom of the coating tank;
A circulation pump and a circulation filter sequentially arranged from the coating liquid tank side in the path of the coating liquid supply pipe;
A return liquid transport pipe that is introduced from the bottom of the coating tank and returns the coating liquid overflowed from the top of the coating tank to the coating liquid tank;
A circulation transport pipe that branches between a circulation pump and a circulation filter in the coating liquid supply pipe and circulates a part of the coating liquid supplied from the bottom of the coating liquid tank to the upper part of the coating liquid tank through a valve; ,
Comprising a cooling means arranged in the path of the circulating transport pipe, and a moisture adsorption tank containing a moisture adsorbent;
With
The coating liquid containing the pigment supplied into the coating tank is maintained at a predetermined temperature by the cooling means of the coating liquid tank, and the moisture in the coating liquid is not increased by the moisture adsorption tank provided with the cooling means. This is characterized in that it is configured to remove the.

In general, pigment-dispersed coating liquids used for electrophotographic photoreceptors have thixotropic properties, and the viscosity increases with time and the thixotropic properties become stronger. appear. Moreover, since an organic solvent is used for the coating liquid, the water content in the coating liquid increases with time. For this reason, there has been a problem that a coating film defect occurs due to coating unevenness due to viscosity non-uniformity and repellency accompanying an increase in water content.
On the other hand, the coating film forming apparatus for the electrophotographic photosensitive member of the present invention is provided with a cooling means in the coating liquid tank, and cools the coating liquid containing the pigment to maintain the coating liquid in the coating tank at a predetermined temperature. At the same time, the moisture adsorbing tank provided with the cooling means is configured to remove moisture in the coating liquid without increasing the temperature.
For this reason, even if the coating liquid containing the pigment is repeatedly circulated, the change in thixotropy with time is small and viscosity nonuniformity does not occur. For this reason, the coating nonuniformity accompanying the nonuniformity of a viscosity and the generation | occurrence | production of the repellency accompanying a water | moisture content increase do not generate | occur | produce, and the uniform and stable coating film is formed.
Hereinafter, the electrophotographic photoreceptor coating film forming apparatus of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view showing one structural example of a coating film forming apparatus for an electrophotographic photosensitive member according to the present invention.
The coating film forming apparatus of FIG. 1 immerses a conductive substrate (1) and dip-coats a coating liquid containing pigment (substantially, “coating liquid”) on the conductive substrate (1). (2), a coating liquid tank (3) having a stirring means (5) for storing the coating liquid and a cooling means (4), and a cooling means (8) for removing water in the coating liquid. And a moisture adsorption tank (7) containing a moisture adsorbent (9).

The coating liquid tank (3) and the coating tank (2) are coated with a coating liquid supply pipe (20) for supplying the coating liquid from the bottom of the coating liquid tank (3) to the bottom of the coating tank (2). It is connected by.
A circulation pump (6) and a circulation filter (10) are sequentially arranged from the coating liquid tank (3) side in the path of the coating liquid supply pipe (20). The coating liquid is continuously supplied from the bottom of the coating liquid tank (3) to the bottom of the coating tank (2) by the circulation pump (6) via the circulation filter (10).

  Then, the coating liquid introduced from the bottom of the coating tank (2) is caused to overflow from the top of the coating tank (2), and the overflowed coating liquid is placed between the coating liquid tank (3) and the coating tank (2). Returned to the coating liquid tank (3) by a return liquid transport pipe (22) provided separately in the above, so that a new coating liquid is always supplied.

On the other hand, the coating liquid tank (3) and the moisture adsorption tank (7) are circulating transport pipes that circulate a part of the coating liquid from the bottom of the coating liquid tank (3) to the top of the working liquid tank (3) ( 23). The circulation transport pipe (23) is a pipe branched between the circulation pump (6) of the coating liquid supply pipe (20) and the circulation filter (10). The circulation pump (6) is used to connect the coating liquid tank (3). A part of the coating liquid supplied from the bottom is circulated through the valve (11) to the upper part of the coating liquid tank (3).
The circulation transport pipe (23) is provided with a cooling means (8) and a moisture adsorption tank (7) containing a moisture adsorbent (9).

  The cooling means (4) of the coating liquid tank (3) and the cooling means (8) of the moisture adsorption tank (7) are configured to cool from the outer surface of each tank (3), and the cooling medium is illustrated. It is designed to circulate with a pump that does not. The cooling medium of the cooling means (4) and (8) is not particularly limited as long as it can maintain the coating liquid at a predetermined temperature (for example, 15 ° C. or lower), and may be water. The cooling medium of the cooling means (4) and (8) may be the same or different. For example, the cooling medium of each cooling means can be the same cooling water.

  FIG. 2 is an enlarged view of the moisture adsorption tank (7) provided with the cooling means (8) in FIG. FIG. 2 shows a case where the cooling water is introduced from the lower part on one side and led out from the upper part on the other side in the cooling means (8) as an example. Reference numeral 21 denotes an opening having a mesh structure.

  It is preferable to maintain the temperature of the coating solution supplied into the coating tank (2) at 15 ° C. or lower. If the temperature is controlled to 15 ° C. or less by the cooling means, an increase in the viscosity of the coating solution can be suppressed for a long time even if the coating solution is repeatedly circulated, and the occurrence of uneven coating is reliably prevented.

Moreover, it is preferable that the coating liquid inflow side to the moisture adsorption tank (7) arranged in the path of the circulation transport pipe (23) is the lower side of the tank, and the coating liquid outflow side is the upper side of the coating liquid tank. .
By comprising in this way, since a coating liquid is conveyed upwards, filling the whole moisture adsorption tank (7), the adsorption | suction of the water | moisture content in a coating liquid can be performed efficiently, and also cooling efficiency increases.

Moreover, it is preferable that a water | moisture-content adsorption agent (9) is filled into an adsorption agent filling container, and this adsorption agent filling container is accommodated in a moisture adsorption tank (7) so that replacement | exchange is possible.
If comprised in this way, replacement | exchange of a moisture adsorption agent will become easy. And when changing a water | moisture-content adsorption agent, it can replace | exchange in the state which closed the said valve | bulb (11) and stopped the circulation of the coating liquid to a water | moisture-content adsorption | suction tank (7). Can be prevented from rising.

  Examples of the material (moisture adsorbent or absorbent) used as the moisture adsorbent (9) include synthetic zeolite (molecular sieve) and silica gel. Particularly preferred is molecular sieve. By using the molecular sieve as the moisture adsorbent, moisture in the coating liquid containing the pigment can be effectively adsorbed and an increase in the amount of moisture can be reliably suppressed.

Here, the coating liquid inflow side and the coating liquid outflow side of the adsorbent-filled container filled with the moisture adsorbent (9) each have an opening of a mesh structure, and particularly when the mesh opening diameter is 130 μm or less. Preferably there is. When the thickness exceeds 130 μm, the filled water adsorbent cannot be satisfactorily retained, coating unevenness occurs, and abnormal images are generated when the coated film is dried to form a pigment-containing layer (photosensitive layer). If it is about 130 micrometers, it can circulate, without reducing a flow volume, hold | maintaining a moisture adsorption agent. If the opening diameter becomes too small, the flow rate decreases due to pressure loss, so it is necessary to select desired conditions as appropriate.
According to the experiment, it is preferable that the circulation flow rate of the coating liquid circulated to the moisture adsorption tank (7) is equal to or less than the supply flow rate of the coating liquid supplied to the coating tank (2).

As shown in FIG. 1, a circulation filter (10) is provided in the path of the coating liquid supply pipe (20), and the coating is supplied to the bottom of the coating tank (2) by the circulation pump (6). The liquid is filtered with a circulation filter (10).
Since the average particle diameter of the pigment of the coating liquid containing the pigment is about 0.2 μm, the mesh of the circulation filter (10) is set to about 5 to 10 μm.
On the other hand, even if a moisture adsorbent (9) having a small particle size is mixed in the coating liquid, it is removed by the circulation filter (10), but the setting conditions of the moisture adsorption tank (7) are not appropriate (for example, open When the aperture exceeds 130 μm), the function of the circulation filter (10) does not function sufficiently, and the occurrence of coating unevenness causes an abnormal image when the coating film is dried to form a photosensitive layer.

  When a dispersion containing a disazo pigment is used as a coating solution containing a pigment, a viscosity increase over time is easily suppressed, and a coating film without coating unevenness or repellency is formed, and the coating film is dried to provide a photosensitive layer. In addition, the electrophotographic photoreceptor can produce a good image without white spots and the like.

Next, a method for forming a coating film on the electrophotographic photoreceptor according to the present invention will be described.
The method for forming a coating film on an electrophotographic photosensitive member in the present invention is carried out using the coating film forming apparatus for the electrophotographic photosensitive member. That is, the method for forming a coating film on an electrophotographic photoreceptor is:
The coating liquid, which is contained in the coating liquid tank (3) having the stirring means (5) and the cooling means (4) and whose liquid temperature is controlled, is applied from the bottom of the coating liquid tank (3) to the coating tank ( 2) to the bottom of the coating liquid supply pipe (20) through the circulation filter (10) by the circulation pump (6),
At the same time, the coating liquid introduced from the bottom of the coating tank (2) and overflowed from the top of the coating tank is returned to the coating liquid tank (3) from the return liquid transport pipe (22),
In parallel, a part of the coating liquid supplied from the bottom of the coating liquid tank (3) is branched between the circulation pump (6) and the circulation filter (11) of the coating liquid supply pipe (20). The circulating transport pipe (23) is circulated through the valve (11) to the upper part of the coating liquid tank (3), and at the time of this circulation, the cooling means (8) provided in the circulating transport pipe (23) is provided. Remove the moisture in the coating liquid without increasing the temperature in the moisture adsorption tank (7),
The conductive substrate (1) is immersed in the temperature-controlled coating solution introduced into the coating tank (2) and then pulled up, and a coating film is formed on the substrate to form a pigment-containing layer by drying after treatment. It is characterized by.

  By the coating film forming method, a uniform and stable coating film with no coating unevenness or repellency is formed. That is, according to the above, even when the coating liquid containing the pigment is repeatedly circulated, the viscosity of the coating liquid does not increase, and therefore there is no occurrence of coating unevenness associated with the viscosity non-uniformity. Moreover, since moisture is reliably adsorbed by the moisture adsorbent and the moisture content in the coating liquid does not increase, no repelling or the like occurs. Furthermore, since the coating liquid can be repeatedly circulated for a long time, the loss of the coating liquid is small and the productivity is good.

Next, there is no occurrence of abnormal images (density unevenness, white spots, etc.) having a pigment-containing layer obtained by drying the coating film formed on the conductive substrate by the above-described electrophotographic photosensitive member coating method. The electrophotographic photoreceptor of the present invention will be described.
Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a cross-sectional view showing one structural example of the electrophotographic photosensitive member in the present invention.
In FIG. 3, a single photosensitive layer 33 mainly composed of a charge generation material and a charge transport material is provided on a conductive substrate 31. FIG. 4 is a cross-sectional view showing another structural example of the electrophotographic photosensitive member in the present invention. FIG. 5 is a cross-sectional view showing still another structural example of the electrophotographic photosensitive member in the present invention.
That is, in the electrophotographic photoreceptor shown in FIG. 4, a charge generation layer 35 mainly composed of a charge generation material and a charge transport layer 37 mainly composed of a charge transport material are sequentially laminated on a conductive substrate 31. The structure is taken. On the other hand, the electrophotographic photosensitive member shown in FIG. 5 has a configuration in which the stacking order of the charge generation layer 35 and the charge transport layer 37 in FIG. 4 is reversed.

  In the above configuration, sensitivity and durability are improved by adopting a function-separated photosensitive layer configuration including a charge generation layer and a charge transport layer. And by drying the coating film formed by immersing the conductive substrate by the coating film forming method of the present invention using a coating liquid containing a charge generating material (pigment), for example, by forming a charge generation layer Thus, a high-quality and highly reliable electrophotographic photosensitive member that does not generate abnormal images can be obtained. In particular, by containing a disazo pigment in the charge generation layer, an electrophotographic photosensitive member having good photosensitive characteristics without occurrence of abnormal images such as white spots can be obtained.

Each constituent layer of the electrophotographic photosensitive member will be described below.
[Conductive substrate]
A typical example of the shape of the conductive substrate (31) is a cylindrical one. Examples of such a conductive substrate (31) are those exhibiting conductivity of a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide In addition, metal oxide such as indium oxide is deposited or sputtered on a film or cylindrical plastic or paper, or a plate made of aluminum, aluminum alloy, nickel, stainless steel or the like and extruded or drawn out. After the tube is made by this method, it is possible to use a tube subjected to surface treatment such as cutting, superfinishing or polishing.

In addition, the conductive substrate 31 of the present invention can be used in which conductive powder is dispersed in a suitable binder resin and coated on the support.
Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, or metal oxide powder such as conductive tin oxide and ITO. It is done.

The binder resin used at the same time includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. Copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin , Thermoplastic resins such as melamine resin, urethane resin, phenol resin, and alkyd resin, thermosetting resin, or photocurable resin.
Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Furthermore, it is electrically conductive by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support 31 of the present invention.

Next, the photosensitive layer will be described. The photosensitive layer may be a single layer or a laminated layer. For convenience of explanation, a case where the photosensitive layer is composed of the charge generation layer 35 and the charge transport layer 37 will be described first.
[Photosensitive layer of laminated structure]
(Charge generation layer)
For the charge generation layer 35, a pigment, particularly an organic pigment, is dispersed in a suitable solvent together with a binder resin, if necessary, using a ball mill, an attritor, a sand mill, an ultrasonic wave, or the like, and preferably has a volume average particle size of 1 μm or less. The conductive substrate is immersed in a coating solution containing a pigment by dip coating, that is, a coating film forming method using the electrophotographic photosensitive member coating film forming apparatus of the present invention. After the coating film is formed, the coating film is dried to form a charge generation layer (pigment-containing layer).
By such dip coating, there is no coating unevenness or repellency, and a uniform coating film is formed and a stable charge generation layer is formed.

  Organic pigments that are photoconductive pigments include metal-free phthalocyanine pigments, oxotitanyl phthalocyanine pigments, mixed crystals of metal phthalocyanine and metal-free phthalocyanine pigments, disazo pigments containing fluorene and fluorenone rings, and aromatic amines. Examples include disazo pigments and trisazo pigments, and metal-free phthalo pigments and azo pigments may be mixed. As described above, the disazo pigment is preferably used as a coating liquid used in the coating film forming apparatus of the present invention.

  As the binder resin used for the charge generation layer 35 as necessary, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicon resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N -Vinylcarbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. Can be mentioned.

  Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. The thickness of the charge generation layer 35 is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

(Charge transport layer)
The charge transport layer 37 can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

  Charge transport materials include hole transport materials and electron transport materials. Examples of the charge transport material include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. Other known materials may be mentioned.
These charge transport materials may be used alone or in combination of two or more.

  Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin And thermoplastic or thermosetting resins such as alkyd resins.

  The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 100 μm. The effect of this case can be more obtained when the thickness is 15 μm or more.

  Examples of the solvent used here include tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, and acetone.

  In addition, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used for the charge transport layer. The charge transport layer composed of these polymer charge transport materials is excellent in wear resistance. A known material can be used as the polymer charge transporting material, but a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the general formulas (1) to (10) exemplified below are favorably used.

  Examples of polymer charge transport materials / general formula (1);

Wherein R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₅ and R ₆ are substituted or unsubstituted Unsubstituted aryl group, o, p and q are each independently an integer of 0 to 4, k and j represent a composition, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and n is a repeating unit And represents an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula (1-1).

[Wherein, R ₁₀₁ and R ₁₀₂ each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO ₂ —. , -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or the following general formula (1-2):

(Wherein, a represents an integer of 1 to 20, b represents an integer of 1 to 2000, R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or an aryl group). Here, R ₁₀₁ and R ₁₀₂ , and R ₁₀₃ and R ₁₀₄ may be the same or different. ]

  Example of polymer charge transport material / general formula (2);

(Wherein R ₇ and R ₈ represent a substituted or unsubstituted aryl group, Ar ₁ , Ar ₂ and Ar ₃ represent the same or different arylene groups. X, k, j and n represent the above general formula (1) Same as in the case of.)

  Example of polymeric charge transport material / general formula (3);

(Wherein R ₉ and R ₁₀ are substituted or unsubstituted aryl groups, Ar ₄ , Ar ₅ and Ar ₆ are the same or different arylene groups. X, k, j and n represent the above general formula (1). Same as in the case of.)

  Example of polymeric charge transport material / general formula (4);

(Wherein R ₁₁ and R ₁₂ are substituted or unsubstituted aryl groups, Ar ₇ , Ar ₈ and Ar ₉ are the same or different arylene groups, and p is an integer of 1 to 5. X, k, j and n Is the same as in the general formula (1).)

  Example of polymer charge transport material / general formula (5);

Wherein R ₁₃ and R ₁₄ are substituted or unsubstituted aryl groups, Ar ₁₀ , Ar ₁₁ and Ar ₁₂ are the same or different arylene groups, X ₁ and X ₂ are substituted or unsubstituted ethylene groups, or substituted or unsubstituted Represents an unsubstituted vinylene group, and X, k, j and n are the same as those in the general formula (1).)

  Example of polymeric charge transport material / general formula (6);

(Wherein R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ and Ar ₁₆ are the same or different arylene groups, Y ₁ , Y ₂ and Y _3. Represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group, which may be the same or different. X, k, j and n are the same as those in the general formula (1).)

  Example of polymer charge transport material / general formula (7);

(In the formula, R ₁₉ and R _{20 each} represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ may be the same or different. Represents an arylene group, and X, k, j and n are the same as those in the general formula (1).

  Example of polymeric charge transport material / general formula (8);

(Wherein R ₂₁ represents a substituted or unsubstituted aryl group, Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , and Ar ₂₃ represent the same or different arylene groups. X, k, j, and n represent the above general formula (1). Same as in the case of.)

  Example of polymeric charge transport material / general formula (9);

(In the formula, R ₂₂ , R ₂₃ , R ₂₄ and R ₂₅ are substituted or unsubstituted aryl groups, and Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ and Ar ₂₈ are the same or different arylene groups. X, k , J and n are the same as those in the general formula (1).)

  Example of polymeric charge transport material / general formula (10);

(In the formula, R ₂₆ and R ₂₇ are substituted or unsubstituted aryl groups, Ar ₂₉ , Ar ₃₀ and Ar ₃₁ are the same or different arylene groups. X, k, j and n represent the above general formula (1). Same as in the case of.)

  In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 37. As the plasticizer, those used as general plasticizers such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is suitably about 0 to 30% by weight based on the binder resin.

As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 0 with respect to the binder resin. 1% by weight is suitable.
The liquid viscosity of the charge transport coating solution in the dip coating method is preferably 100 mPa · s or more, and preferably 300 to 1000 mPa · s.

[Single layer photosensitive layer]
Next, the case of the single photosensitive layer 33 having a single photosensitive layer structure will be described.
A photoreceptor in which a pigment is dispersed in a binder resin can be used. The single-layer photosensitive layer 33 can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance, and a binder resin in a suitable solvent, and applying and drying them. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

As the binder resin, the binder resin previously mentioned in the charge transport layer 37 is used as it is, and the binder resin mentioned in the charge generation layer 35 may be mixed and used. Of course, the polymer charge transport materials mentioned above can also be used favorably. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight, and more preferably 50 to 150 parts by weight.
The single-layer photosensitive layer is formed by using a coating solution in which a charge generating material and a binder resin are dispersed together with a charge transporting material, if necessary, using a solvent such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane by a dispersing machine. It can be formed by the dip coating method of the invention. The thickness of the single photosensitive layer is suitably about 5 to 50 μm.

Next, an image forming apparatus and an image forming method using the electrophotographic photosensitive member of the present invention will be described in detail with reference to the drawings.
FIG. 6 is a schematic view for explaining the electrophotographic process and the electrophotographic apparatus of the present invention. In FIG. 6, an electrophotographic photosensitive member (photosensitive member) 51 is a conductive layer having a pigment-containing layer formed by drying a coating film formed by a coating film forming method using the coating film forming apparatus of the present invention. Provided on the conductive substrate.

  For the pre-transfer charger 57, the transfer charger 60, the separation charger 61, and the pre-cleaning charger 63, known means such as a corotron, a scorotron, a solid state charger (solid state charger), and a charging roller are used. As the transfer means, the above charger can be generally used. However, as shown in the figure, a combination of the transfer charger 60 and the separation charger 61 is effective.

  Light sources such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), an electroluminescence (EL), etc. All things can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  The toner developed on the photoconductor 51 by the developing unit 56 is transferred to the transfer paper 59, but not all is transferred, and some toner remains on the photoconductor 1. Such toner is removed from the photoreceptor by the fur brush 64 and the cleaning blade 65. Cleaning may be performed only with a cleaning brush. In this case, known cleaning brushes such as a fur brush and a mag fur brush are used.

  When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. When this is developed with negative (positive) polarity toner (electrodetection fine particles), a positive image can be obtained, and when developed with positive (negative) polarity toner, a negative image can be obtained. A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.

  Since the image forming apparatus having the above configuration includes the electrophotographic photosensitive member of the present invention, high quality and reliability are maintained even when used repeatedly. In addition, according to the image forming method performed by such an image forming apparatus, abnormal images such as density unevenness and white spots are not generated, and stable and high-quality and reliable image formation can always be performed. .

  The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photosensitive member and includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. Although there are many shapes and the like of the process cartridge, a general example is a configuration example shown in the schematic diagram of FIG.

In FIG. 7, 76 denotes a photosensitive member, 77 denotes a charging charger as a charging unit, 78 denotes a cleaning brush as a cleaning unit, 79 denotes an image exposure unit as an exposure unit, and 80 denotes a developing roller as a developing unit.
The photoreceptor 76 has a photosensitive layer including a pigment-containing layer formed by drying a coating film formed by a coating film forming method using the coating film forming apparatus of the present invention provided on a conductive substrate. .

  According to the above configuration, it is possible to provide a process cartridge in which abnormal images such as density unevenness and white spots do not occur even when used repeatedly, and the apparatus can be reduced in size and maintainability can be improved.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples. “Parts” are all in weight units.

Example 1
A coating solution for the undercoat layer, the charge generation layer, and the charge transport layer is prepared under the following conditions, which are sequentially provided on a conductive cylindrical substrate made of aluminum having an outer diameter of 30 mm and a length of 340 mm. 100 bodies were produced.

<Underlayer>
The composition of the following formulation was dispersed for 72 hours with a ball mill using aluminum balls to prepare an undercoat layer coating solution.
<Prescription of undercoat layer coating solution>
Titanium oxide powder: 50 parts Alkyd melamine resin: 25 parts Methyl ethyl ketone: 100 parts

  The undercoat layer coating solution was dip coated on a conductive substrate and dried at 130 ° C. for 20 minutes to form an undercoat layer having a thickness of 4 μm. In addition, 100 pieces were produced under the same conditions.

<Charge generation layer>
Next, according to the following formulation, a solution in which polyvinyl butyral was dissolved in a ball mill and a disazo pigment powder were all added and dispersed for 150 hours to prepare a charge generation layer coating solution.
<Formulation of charge generation layer coating solution>
Disazo pigment powder represented by the following structural formula (a): 50 parts Polyvinyl butyral: 5 parts Methyl ethyl ketone: 300 parts Cyclohexanone: 3000 parts

The charge generation layer coating solution is filled in the coating solution tank of the coating film forming apparatus shown in FIG. 1, and the moisture adsorption tank and the coating solution tank are cooled to maintain the coating solution temperature at 15 ° C. The charge generation layer coating solution was circulated for months. That is, the coating liquid is supplied from the coating liquid tank to the coating layer, and the overflowed coating liquid returns to the coating liquid tank, and also circulates from the coating liquid tank to the coating liquid tank through the moisture adsorption tank. is doing. In addition, the mesh opening length of the moisture adsorption tank was 130 μm, and molecular sieve (synthetic zeolite) was filled as the moisture adsorbent.
After immersing the conductive substrate on which the undercoat layer has been formed in the charge generation layer coating liquid (coating tank) after one month of circulation, the film is pulled up to form a coating film. Each coating was dried at 130 ° C. for 30 minutes to form a charge generation layer.

<Charge transport layer>
Next, a charge transport layer coating solution was prepared by uniformly mixing the components of the following formulation.
<Prescription of charge transport layer coating solution>
Polycarbonate: 15 parts Charge transport material represented by the following structural formula (b): 7 parts Tetrahydrofuran: 70 parts

  The conductive substrate on which the charge generation layer was previously formed was dip-coated in the charge transport layer coating solution, and then dried at 130 ° C. for 30 minutes to form a charge transport layer having a thickness of 30 μm. 100 electrophotographic photoreceptors were produced.

(Comparative Example 1)
In Example 1, except that the coating liquid tank was cooled and circulated while keeping the temperature of the coating liquid at 15 ° C., except that the coating liquid tank was not cooled (room temperature 25 ° C.). 100 electrophotographic photoreceptors of Comparative Example 1 were produced in exactly the same manner as in Example 1.

(Comparative Example 2)
Example 1 is the same as Example 1 except that the moisture adsorption tank was cooled and circulated while maintaining the temperature of the coating liquid at 15 ° C., except that the moisture adsorption tank was not cooled (room temperature 25 ° C.). 100 electrophotographic photosensitive members of Comparative Example 2 were produced in exactly the same manner.

(Comparative Example 3)
In Example 1, the coating liquid was changed from passing from the coating liquid tank to the coating liquid tank through the moisture adsorption tank and circulated to the coating liquid tank. Similarly, 100 electrophotographic photoreceptors of Comparative Example 3 were produced.

(Comparative Example 4)
The electrophotographic photosensitive member of Comparative Example 4 was prepared in the same manner as in Example 1 except that the mesh opening diameter of the moisture adsorption tank in Example 1 was 130 μm and that the mesh opening diameter was 155 μm. 100 were produced.

  Each of the 100 electrophotographic photoreceptors prepared in Example 1 and Comparative Examples 1 to 4 was visually inspected for the state of the coating film, evaluated for the occurrence of coating unevenness and repellency, and further laser printers. The quality of the image was evaluated. The results are shown in Table 1 below.

From the evaluation results in Table 1 above, all of the electrophotographic photoreceptors of the examples in which the coating film was formed by the coating film forming method using the coating film forming apparatus of the present invention to form the charge generation layer were coated unevenness and repellency. It can be seen that there is no occurrence of abnormal images in the image quality by the laser printer. On the other hand, Comparative Example 1 without temperature control of the coating liquid tank, Comparative Example 2 without temperature control of the moisture adsorption tank, Comparative Example 3 without circulation to the moisture adsorption tank, and the mesh opening length of the moisture adsorption tank was set to 155 μm In the case of Comparative Example 4, it can be seen that many defective products (NG) are generated.
By using the coating film forming apparatus of the present invention, it is possible to form a uniform and stable coating film without occurrence of coating unevenness and repellency, and an electron that does not generate abnormal images (density unevenness, white spots, etc.). A photographic photoreceptor is obtained. If this electrophotographic photosensitive member is mounted on an image forming apparatus or a process cartridge for an image forming apparatus, a high-quality image can be stably formed.

It is the schematic which shows one structural example of the coating-film formation apparatus of the electrophotographic photoreceptor in this invention. It is an enlarged view of the water | moisture-content adsorption | suction tank (7) which comprises the cooling means (8) in FIG. FIG. 2 is a cross-sectional view showing an example of the configuration of the electrophotographic photosensitive member in the present invention. It is sectional drawing which shows another structural example of the electrophotographic photoreceptor in this invention. It is sectional drawing which shows another example of a structure of the electrophotographic photoreceptor in this invention. It is the schematic for demonstrating the electrophotographic process and electrophotographic apparatus of this invention. It is a schematic diagram showing a configuration example of a process cartridge of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive substrate 2 Coating tank 3 Coating liquid tank 4 Cooling means 5 Stirring means 6 Sequential circulation pump 7 Moisture adsorption tank 8 Cooling means 9 Moisture adsorbent 11 Valve 10 Circulating filter 20 Coating liquid supply pipe 21 Opening of mesh structure Section 22 Return liquid transport pipe 23 Circulating transport pipe 31 Conductive substrate 33 Photosensitive layer 35 Charge generation layer 37 Charge transport layer 51 Photoconductor 52 Static elimination lamp 55 Image exposure section 56 Development unit 57 Pre-transfer charger 59 Transfer paper 60 Transfer charger 61 Separation Charger 63 Pre-cleaning charger 64 Fur brush 65 Cleaning blade 76 Photoconductor 77 Charger 78 Cleaning brush 79 Image exposure unit,
80 Development roller

Claims (15)

A coating film forming apparatus for an electrophotographic photosensitive member, wherein a conductive substrate is immersed in a coating solution containing at least a pigment, and a coating film is formed on the substrate to form a pigment-containing layer by post-processing drying,
The device is
A coating tank for dip-coating a coating liquid containing a pigment on a conductive substrate;
A coating liquid tank that contains a stirring means and a cooling means for containing a coating liquid containing the pigment;
A coating liquid supply pipe for supplying a coating liquid from the bottom of the coating liquid tank to the bottom of the coating tank;
A circulation pump and a circulation filter sequentially arranged from the coating liquid tank side in the path of the coating liquid supply pipe;
A return liquid transport pipe that is introduced from the bottom of the coating tank and returns the coating liquid overflowed from the top of the coating tank to the coating liquid tank;
A circulation transport pipe that branches between a circulation pump and a circulation filter in the coating liquid supply pipe and circulates a part of the coating liquid supplied from the bottom of the coating liquid tank to the upper part of the coating liquid tank through a valve; ,
Comprising a cooling means arranged in the path of the circulating transport pipe, and a moisture adsorption tank containing a moisture adsorbent;
With
The coating liquid containing the pigment supplied into the coating tank is maintained at a predetermined temperature by the cooling means of the coating liquid tank, and the moisture in the coating liquid is not increased by the moisture adsorption tank provided with the cooling means. An apparatus for forming a coating film on an electrophotographic photosensitive member, wherein the coating film forming apparatus is configured to remove the toner.   2. The coating film forming apparatus for an electrophotographic photosensitive member according to claim 1, wherein a predetermined temperature of the coating liquid supplied into the coating tank is 15 [deg.] C. or less.   The coating liquid inflow side to the moisture adsorption tank disposed in the path of the circulation transport pipe is configured to be the lower side of the moisture adsorption tank, and the coating solution outflow side is configured to be the upper side of the moisture adsorption tank. The electrophotographic photoreceptor coating film forming apparatus according to claim 1 or 2.   4. The coating film forming apparatus for an electrophotographic photosensitive member according to claim 1, wherein the moisture adsorbent is filled in an adsorbent filling container that is exchangeably stored in a moisture adsorption tank. .   5. The coating film forming apparatus for an electrophotographic photosensitive member according to claim 4, wherein the moisture adsorbent is a synthetic zeolite (molecular sieve).   6. The electrophotographic photosensitive member according to claim 4 or 5, wherein the coating liquid inflow side and the coating liquid outflow side of the adsorbent filling container filled with the moisture adsorbent respectively have openings of mesh structure. Body coating device.   The coating film forming apparatus for an electrophotographic photosensitive member according to claim 6, wherein an opening diameter in the opening portion of the mesh structure is 130 μm or less.   The coating film forming apparatus for an electrophotographic photosensitive member according to claim 1, wherein the coating liquid containing the pigment is a dispersion liquid containing a disazo pigment. A method for forming a coating film on an electrophotographic photoreceptor, comprising immersing a conductive substrate in a coating solution containing at least a pigment, and forming a coating film on the substrate to form a pigment-containing layer by post-processing drying,
The method
Using the electrophotographic coating film forming apparatus according to claim 1,
A coating liquid containing a pigment contained in a coating liquid tank having a stirring means and a cooling means and whose liquid temperature is controlled is circulated in a path from the bottom of the coating liquid tank to the bottom of the coating tank and circulated in the path. Supply the filter from the coating liquid tank side through the coating liquid supply pipe,
The coating liquid introduced from the bottom of the coating tank and overflowed from the top of the coating tank is returned to the coating liquid tank by a return liquid transport pipe,
In parallel, a part of the coating liquid supplied from the bottom of the coating liquid tank is branched between a circulation pump and a circulation filter of the coating liquid supply pipe, and the moisture adsorption tank provided with a cooling means is routed. Circulate to the upper part of the coating liquid tank through a valve with the deployed circulating transport pipe, and remove the water in the coating liquid without increasing the temperature in the moisture adsorption tank containing the moisture adsorbent in the circulation path.
An electrophotographic method comprising: dipping a conductive substrate in a temperature-controlled coating solution introduced into the coating tank; and then pulling the film to form a pigment-containing layer on the substrate by drying after treatment. A method for forming a coating film on a photoreceptor. An electron having a pigment-containing layer obtained by drying a coating film formed by dip-coating a conductive substrate in a coating solution containing at least a pigment by the method for forming a coating film on an electrophotographic photosensitive member according to claim 9. A photographic photoreceptor,
The electrophotographic photoreceptor, wherein the pigment-containing layer is a photosensitive layer containing a photoconductive pigment.   The electrophotographic photoreceptor according to claim 10, wherein the pigment-containing layer is a charge generation layer in a photosensitive layer having a laminated structure of a charge generation layer and a charge transport layer.   The electrophotographic photosensitive member according to claim 11, wherein the charge generation layer contains a disazo pigment. An image forming method including steps of charging, exposing, developing and transferring an electrophotographic photosensitive member,
An image forming method, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 10.   An image forming apparatus comprising at least a charging unit, an exposure unit, a developing unit, a transfer unit, and the electrophotographic photosensitive member according to claim 10. 13. An image forming apparatus comprising at least the electrophotographic photosensitive member according to claim 10 and at least one unit selected from a charging unit, an exposure unit, a developing unit, and a cleaning unit. Process cartridge.

Images