JP2006337545A - Method for manufacturing film covered substrate and method for manufacturing electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a film covered substrate by which a smooth film free from pinholes, bubbles, surface unevenness, etc., can easily be formed in a short period of time. <P>SOLUTION: A film 6 is formed on a substrate 5 by applying a coating liquid containing photosensitive layer forming materials and a solvent in which a solvent whose relative evaporation rate represented by following expression (1) is <1.7 is contained in an amount of ≥30 wt.%; expression (1): (relative evaporation rate)=(time in which n-butyl acetate evaporates)/(time in which solvent evaporates). The objective film covered substrate is manufactured using a drying apparatus 1 by heating the substrate 5 to 60-150°C by an induction heating means 2 and then drying the film 6 by heating by a far infrared heating means 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a coating film-coated substrate and a method for producing an electrophotographic photosensitive member.

  An electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) used in an image forming apparatus such as a copying machine, a printer, or a facsimile is formed by coating an organic photosensitive layer on the outer peripheral surface of a hollow cylindrical conductive substrate. The Many electrophotographic photoreceptors have been developed in response to demands for higher performance, and have a laminated structure in which an undercoat layer, a charge generation layer, a charge transport layer, a protective layer, and the like are laminated. A layer including at least two layers of a charge generation layer and a charge transport layer, or a single layer charge generation / transport layer containing a charge generation material and a charge transport material is referred to as a photosensitive layer.

  As an image forming method using an electrophotographic photosensitive member, an electrophotographic image forming method using a photoconductive phenomenon of the photosensitive member as described below is widely used. First, the photosensitive member is placed in a dark place, and the surface of the photosensitive member is uniformly charged by charging means, and then exposure corresponding to image information is performed to selectively discharge the surface charge of the exposed portion. As a result, the surface charge remains only in the non-exposed portion of the photoreceptor, and a difference occurs between the surface charge amount in the exposed portion and the surface charge amount in the non-exposed portion, and an electrostatic latent image is formed. Next, colored fine particles called toner are adhered to the formed electrostatic latent image by electrostatic attraction or the like to form a visible toner image. The formed toner image is transferred onto a transfer material such as paper and fixed as necessary to form an image.

  A photoreceptor used in an image forming apparatus that forms an image through a series of electrophotographic processes as described above has excellent electrical characteristics as a basic characteristic, for example, excellent charge retention capability, and charge in a dark place. There are demands for low discharge, excellent photosensitivity, and rapid discharge of light by light irradiation. In addition, the photoreceptor has stable electrical characteristics as described above (repetitive stability) and changes in temperature and humidity so that a uniform image can be formed over a long period of time. In addition, it is also required that the above-mentioned electrical characteristics are stable (environmental stability) so that a homogeneous image can be formed. In order to increase the cycle stability and the environmental stability, it is necessary to increase the durability against electrochemical action and mechanical external force during operation.

  The durability against the electrochemical action accompanying operation includes, for example, the durability against deterioration of the surface layer due to adhesion of active substances such as ozone and NOx (nitrogen oxide) generated by corona discharge during charging. In addition, the durability against mechanical external force includes the abrasion resistance and abrasion resistance that occur during transfer due to rubbing with a transfer material such as paper, etc., especially depending on the surface condition of the outermost surface layer of the photoreceptor. It is determined. For example, if the surface state of the photoconductor is not smooth and uneven, there is a problem that the frictional force during transfer increases in part of the surface layer and surface damage occurs, resulting in durability against mechanical external forces. descend. For example, when there are pores in the surface layer of the photosensitive member, the surface area to which the active substance generated during charging adheres increases and the durability against electrochemical action decreases. Therefore, it is indispensable to smooth the surface layer of the photoreceptor in order to improve the repetition stability and the environmental stability.

  An electrophotographic photoreceptor is conductive by spraying, ring coating, roll coating, blade, dipping, etc. with a coating solution in which a photosensitive layer forming material such as an organic functional material or binder resin is dissolved or dispersed in a solvent. A coating process for coating the substrate with a uniform thickness (hereinafter, a coating solution coated on the conductive substrate is referred to as a coating film), and drying for removing the solvent contained in the coating film by drying the coating film. It is manufactured through processes. Conventionally, the drying process is a batch type in which a certain number of conductive substrates on which a coating film has been formed are placed in an oven, and dried by blowing hot air at a temperature equal to or higher than the boiling point of the solvent. It is performed by a continuous method in which it is passed through a heat treatment furnace in which a plurality of heaters are installed and dried.

  However, when the coating film is dried with hot air, a heater, etc. as described above, a portion that is directly exposed to hot air, heat from the heater, etc., and a portion that is indirectly applied to the surface of the coating film are generated and heated to the surface of the coating film. Unevenness occurs, and this also causes unevenness of the surface state of the coated film after drying. Moreover, since the coating film surface is dried before the inside of the coating film, the surface becomes a very dense cured film by curing by drying. In the process of forming such a cured film, the viscosity of the coating film increases in the vicinity of the coating film surface, and it is difficult for the solvent gas inside the coating film heated and vaporized to escape from the coating film surface. As a result, defects such as bubbles and pinholes are generated on the surface and inside of the coating film, and defects such as film repelling that make it easier to peel off the coating film applied to the upper surface of the coating film surface. There are things to do. If there are such defects in the surface layer of the photoreceptor, cracks, peeling, etc. are likely to occur, and the durability against electrochemical action and mechanical external force will be reduced, so good repeatability and environmental stability will be achieved. Can't get.

  Further, drying of the formed coating film with hot air, a heater or the like takes time of 1 to several hours, and the production efficiency is lowered. In order to improve the production efficiency, if a large continuous drying furnace, a batch type oven or the like is used in the production line, the running cost and the maintenance cost are also high.

  As a method for solving such a problem, a method of directly heating the coating material itself or indirectly heating the coating film by heating the conductive substrate to dry the coating material has been proposed (for example, Patent References 1 to 6). Patent Document 1 discloses a method in which dielectric material is used to vibrate and heat constituent material molecules of a coating film to dry the coating film. Patent Documents 2 to 4 disclose a method of drying a coating film by using a far-infrared heater so that the constituent material of the coating film itself absorbs far-infrared rays and heats it. Patent Document 5 discloses a method in which a metal conductive substrate is heated by an induction heating method and the coating film is dried by heat generated from the conductive substrate. In patent document 6, the method of drying a coating film combining the induction heating method and methods other than the induction heating method used as needed is disclosed.

  According to the methods disclosed in Patent Documents 1 to 6, the coating material itself can be directly heated, or the inside of the coating can be heated and dried indirectly by heating the conductive substrate. Unevenness of heating can be reduced, and unevenness of the coating film surface after drying is reduced. In addition, according to these methods, it is possible to dry from the inside of the coating film, and it is possible to prevent the formation of a cured film formed by the progress of drying from the surface of the coating film. It is said that the solvent can be removed and dried, and the drying time can be shortened.

  However, these drying methods have the following problems. In the method using dielectric heating disclosed in Patent Document 1, if the metal conductive substrate is not grounded, a spark is generated from the edge portion, and the solvent in the vaporized coating film may ignite and explode. is there. In addition, the material heated by this method is only a dielectric having a dipole, and its heating efficiency is determined by the dielectric loss tangent tan δ which is an inherent value of the coating film constituent material, so it is used as a solvent for the coating solution. The material will be limited.

  In the heating and drying method using far infrared rays disclosed in Patent Documents 2 to 4, the constituent molecules of the coating film absorb the far infrared rays and heat them, so that high heating efficiency can be obtained for the coating film. Infrared rays are not absorbed and the metal conductive substrate is not heated. Therefore, even if the coating film is heated in the initial stage of drying, heat is conducted from the lower part of the coating film to the conductive substrate, and the heat conducted to the conductive substrate is released to the outside. It takes a long time to dry. In particular, when a large continuous drying furnace corresponding to mass production is used, a decrease in heating efficiency due to this heat radiation becomes a serious problem, and drying may take a longer time than drying with hot air.

  In the drying method based on the induction heating method disclosed in Patent Document 5, the metal conductive substrate is heated and the coating film is dried by the heat generated from the conductive substrate. However, the heating efficiency is higher than the heating method using hot air or a heater. Is very high, and the temperature of the coating film may increase rapidly, which makes it difficult to control the temperature of the coating film. In addition, when the temperature of the coating film is rapidly increased, there is a problem that the temperature of the coating film rises to a temperature higher than the heat resistance temperature of the photoreceptor and the electrical characteristics of the photoreceptor are deteriorated.

  Regarding the coating film drying method that combines the induction heating method disclosed in Patent Document 6 and a method other than the induction heating method used as necessary, the coating film is dried by the induction heating method. As in the method disclosed in the above, temperature management is difficult. Also, when using the induction heating method especially for those containing a low boiling point solvent such as tetrahydrofuran as the solvent for the coating film, use the induction heating method that the coating film surface hardens in a short time and can be heated from inside the coating film. There is a possibility that the effect of cannot be expressed.

JP 58-102238 A Japanese Patent Laid-Open No. 3-233895 Japanese Patent Publication No. 5-50742 JP-A-11-311871 JP 2003-275670 A Japanese Patent Laid-Open No. 2-72366

  An object of the present invention is to provide a method for producing a coating film-coated substrate and a method for producing an electrophotographic photosensitive member, which can easily form a smooth coating film free from pinholes, bubbles and surface unevenness in a short time. It is.

The present invention provides a method for producing a coating film-coated substrate having a coating film formed by applying a coating solution containing a coating film-forming material and a solvent on a metal substrate.
A coating process in which a coating liquid containing a coating film forming material and a solvent is coated on a substrate to form a coating film;
An induction heating step of heating the substrate on which the coating film is formed to 60 ° C. or more and 150 ° C. or less by an induction heating method;
A far-infrared heat drying step for drying the coating film formed on the substrate by heating with a far-infrared heating method,
When the ratio of the evaporation time of n-butyl acetate and the evaporation time of the solvent is the relative evaporation rate of the solvent,
In the method for producing a coating film-coated substrate, the solvent contains a solvent having a relative evaporation rate of less than 1.7 by 30% by weight or more.

In the present invention, the substrate has a cylindrical shape or a columnar shape,
The induction heating step and the far infrared heating drying step are:
The substrate is held such that the axial direction is parallel to the horizontal direction, and the substrate is rotated around the axial line.

In the present invention, the metal substrate is a conductive substrate,
The coating film forming material is a photosensitive layer forming material,
The method for producing an electrophotographic photosensitive member according to the method for producing a coating-coated substrate, wherein the coating-coated substrate is an electrophotographic photosensitive member.

  According to the present invention, the solvent of the coating solution for forming the coating film contains 30% by weight or more of the solvent having a relative evaporation rate of less than 1.7, and the substrate on which the coating film is formed is heated at 60 ° C. by the induction heating method. The coating film-coated substrate is manufactured by heating to 150 ° C. or less and then heating and drying the coating film formed on the substrate with far infrared rays. By heating the substrate by induction heating before heating by the far infrared heating method, the heat conducted from the coating film during the far infrared heating drying process is released from the substrate and the temperature is lowered. Therefore, the coating film can be dried in a short time. In addition, heating by the induction heating method is performed to raise the substrate to a predetermined temperature, and is not performed for a long time so that the coating film is dried. There is no need for temperature control. Furthermore, since the coating film is dried by far-infrared heating, and the coating film can be dried from the inside, it becomes difficult to form a cured film on the surface of the coating film, and the internal solvent can be sufficiently removed. . This makes it possible to easily produce a coating-coated substrate having a smooth coating film free from pinholes, bubbles and surface irregularities in a short time.

  In addition, since the solvent in the coating solution contains a solvent having a relative evaporation rate of less than 1.7% by weight of 30% by weight or more, the evaporation rate of the solvent in the coating solution becomes slow. As a result, during the coating process, the surface of the coating film is rapidly dried compared to the inside of the coating film during the period from the coating process to the induction heating process and from the induction heating process to the far infrared heating drying process. And the formation of a cured film on the surface of the coating film can be prevented.

  Furthermore, by setting the temperature of the substrate in the induction heating step to 60 ° C. or more and 150 ° C. or less, the temperature of the substrate can be sufficiently increased, and the stability of the coating film with respect to the temperature can be maintained.

  In addition, according to the present invention, the induction heating step and the infrared heating drying step are performed while rotating the cylindrical or columnar substrate, which is held so that the axis is horizontal, around the axis. Then, the coating liquid having increased fluidity can be prevented from dripping in the direction of gravity through the substrate due to gravity, and the film thickness in the circumferential direction and axial direction of the cylindrical and columnar substrates can be made uniform. Further, by rotating the cylindrical and columnar substrates around the axis, heating around the axis by far infrared rays can be made uniform, and unevenness of the coating film surface after drying can be reduced.

  According to the present invention, the metal substrate is a conductive substrate, the coating film forming material is a photosensitive layer forming material, and the coating film coated substrate is an electrophotographic photosensitive member. As a film, an electrophotographic photosensitive member having a smooth coating film free from pinholes, bubbles, and surface unevenness can be easily formed in a short time without impairing electrical characteristics.

  The method for producing a coating film-coated substrate of the present invention comprises a coating step in which a coating solution containing a coating film forming material and a solvent is coated on the substrate to form a coating film, and an induction heating method for the substrate on which the coating film is formed. N-butyl acetate evaporates, including an induction heating step of heating to 60 ° C. or more and 150 ° C. or less, and a far infrared heating drying step of drying the coating film formed on the substrate by heating by a far infrared heating method. When the ratio between the time and the solvent evaporating time is defined as the relative evaporation rate of the solvent, the solvent contains 30% by weight or more of a solvent having a relative evaporation rate of less than 1.7.

  The method for producing a coated substrate according to the present invention includes, for example, applying a coating solution containing a photosensitive layer forming material and a solvent on a conductive substrate made of metal, and drying the coated film. It can be used as a method for producing an electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor) in which a photosensitive layer is formed on a substrate. Hereinafter, a method for producing an electrophotographic photosensitive member of the present invention, which is an embodiment of a method for producing a coating film-coated substrate of the present invention, will be described.

  In the present invention, the coating solution applied on the conductive substrate is called a coating film. Further, the whole liquid having a property capable of dissolving or dispersing a photosensitive layer forming material such as an organic functional material or a binder resin is called a solvent, and one or more substances constituting the solvent are called a solvent. Further, a layer comprising at least two layers of a charge generation layer and a charge transport layer, or a single charge generation / transport layer containing a charge generation material and a charge transport material is referred to as a photosensitive layer.

  First, a drying apparatus that performs the induction heating step and far-infrared heat drying step included in the method for manufacturing an electrophotographic photosensitive member of the present invention will be described, and then the electrophotographic photosensitive member of the present invention using the drying device will be described. A method will be described.

  FIG. 1 is a side view showing a simplified configuration of a drying apparatus 1 for carrying out an induction heating step and a far infrared heating drying step in the method for producing an electrophotographic photosensitive member of the present invention. The drying apparatus 1 includes an induction heating unit 2 that heats the metallic conductive substrate 5 on the surface of which the coating film 6 is formed by induction heating, and far infrared rays are applied to the coating film 6 that is formed on the conductive substrate 5. Far-infrared heating means 3 for irradiating and heating, blower nozzle 4 for supplying warm air to the coating film 6 formed on the conductive substrate 5, and a cylindrical shape on which the coating film 6 to be dried is formed Rotating means 7 for rotating the conductive substrate 5 around its axis is configured.

  The drying apparatus 1 includes a control unit that controls the operation of the entire apparatus, a substrate temperature detection unit that detects the temperature of the conductive substrate heated by the induction heating unit 2, and outputs the detected temperature to the control unit. Detecting the temperature of the coating film 6 heated by the far-infrared heating means 3 and outputting the detected temperature to the control means; and heating the conductive substrate 5 directly above the induction heating means 2 by far-infrared heating Although it is provided with a moving means for moving directly below the means 3, the illustration is omitted. The control means is realized by a central processing unit (CPU) or the like, and controls the operation of the entire apparatus including the far infrared heating means 3 and the blower nozzle 4. The temperature detection by the substrate temperature detection means and the coating film temperature detection means is performed by, for example, a non-contact radiation thermometer.

  The conductive substrate 5 is a cylindrical conductive substrate made of metal such as aluminum. A coating film 6 is formed on the surface of the conductive substrate 5 by applying a solvent in which the photosensitive layer forming material is dispersed or dissolved in a coating process described later. The conductive substrate 5 is held in parallel with the axis in the horizontal direction, and is supported so as to be rotatable around the axis by rotation means 7 having a motor (not shown). The conductive substrate 5 is movably supported so as to be disposed immediately above the induction heating means 2 in the induction heating process and to be disposed directly below the far infrared heating means 3 in the far infrared heating drying process.

  The movement of the conductive substrate 5 from directly above the induction heating means 2 to directly below the far infrared heating means 3 is performed by a moving means (not shown). The moving means moves the conductive substrate 5 horizontally in a direction orthogonal to the axial direction while holding the conductive substrate 5 so that the axial direction is horizontal. The operation of the moving means is controlled by the control means. For example, when the conductive substrate 5 whose temperature is detected by the substrate temperature detecting unit is heated by the induction heating unit 2 to be described later and the temperature reaches a predetermined temperature, the control unit detects the conductive substrate 5 as a far infrared heating unit. 3 so that it is arranged immediately below.

  The induction heating means 2 includes a flat induction coil and an output power source (not shown). The induction heating means 2 causes a current to flow from an output power source (not shown) to the induction coil, and generates a magnetic field by the current. As a result, an eddy current flows through the conductive substrate 5 so as to cancel the magnetic field generated by the induction coil. The induction heating means 2 thus causes a current to flow through the conductive substrate 5 and heats the conductive substrate 5 using the resistance heat generation of the eddy current. The heating of the conductive substrate 5 by the induction heating means 2 is determined by the material, thickness, etc. of the conductive substrate 5.

  The far infrared heating means 3 includes an output power source (not shown), and heats the coating film 6 by irradiating the coating film 6 formed on the conductive substrate 5 with far infrared rays. As the far infrared heating means 3, for example, a ceramic heater, a sheathed heater, a halogen lamp heater, a quartz tube heater or the like can be used. Among these, a ceramic heater that has a long life and can easily change the shape of the heater is particularly preferable.

  The far-infrared heating means 3 is provided longer than the conductive substrate 5 in the axial direction of the cylindrical conductive substrate 5 in order to uniformly heat the coating film 6 formed on the conductive substrate 5. Is preferred. On the opposite side of the conductive substrate 5 from the side facing the far-infrared heating means 3, a reflector (not shown) is provided. The reflector reflects the heat released from the heated coating film 6 and can effectively use the reflected heat for heating the coating film 6.

  The blower nozzle 4 is used to blow a gas against the coating film 6 applied to the conductive substrate 5. For example, a blower or an air shower is used as the blower nozzle 4. The blower nozzle 4 is provided with a hepa filter (not shown) that supplies clean gas to the conductive substrate 5 by filtering the gas. The hepa filter removes foreign matters such as dust and dust in the gas supplied from the blowing nozzle 4 to the conductive substrate 5 to prevent them from adhering to the coating film 6 and is generated when used as a photoconductor. Prevent image defects.

  Hereinafter, the manufacturing method of the electrophotographic photosensitive member of the present invention which is carried out using such a drying apparatus 1 will be described. As described above, the method for producing a photoreceptor of the present invention includes a coating process, an induction heating process, and a far infrared heating drying process.

  In the coating step, a coating solution 6 containing a photosensitive layer forming material and a solvent is applied onto the metallic conductive substrate 5 to form the coating film 6. The coating process can be performed by a known method, and a spray method, a ring coating method, a roll coating method, a blade method, a dipping method, or the like can be used.

  As the metal conductive substrate 5, for example, a metal material such as aluminum, aluminum alloy, copper, zinc, stainless steel, or titanium can be used. Further, the surface of the conductive substrate 5 may be subjected to surface treatment with an anodized film treatment, chemicals, hot water, or the like within a range that does not affect the image quality of an image formed when used as a photoconductor. Alternatively, irregular reflection treatment such as coloring treatment or roughening the surface may be performed. In the electrophotographic process using a laser as an exposure light source, the wavelengths of the incident laser light are uniform, so that the incident laser light and the light reflected in the electrophotographic photosensitive member cause interference, and interference fringes due to this interference are imaged. Appearing above may cause image defects. By performing the irregular reflection treatment as described above on the surface of the conductive substrate, it is possible to prevent image defects due to interference of laser light having the same wavelength.

Here, when performing the induction heating process and the far-infrared heating drying process in the manufacturing method of the photoreceptor of the present invention for the coating film 6 of the photosensitive layer formed on the conductive substrate 5, the solvent of the coating solution used in the coating process. As for the relative evaporation rate of the solvent, which is the ratio of the time for evaporating n-butyl acetate and the time for evaporating the solvent, that is, 30% by weight of the solvent having a relative evaporation rate of less than 1.7 shown in the following formula (1). % Contained at least.
(Relative evaporation rate)
= (Time for n-butyl acetate to evaporate) / (Time for solvent to evaporate) (1)

  The induction heating step and far-infrared heating drying step included in the method for producing a photoreceptor of the present invention are preferably performed for all layers formed on the conductive substrate. However, the cost and the like required for these steps are considered. From which one or more selected layers may be performed. The layer that is not subjected to the induction heating step and the far infrared heating drying step may be left at, for example, room temperature for one hour after the coating step included in the method of the present invention, or may be charged into a drying furnace.

  If the surface state of the surface layer of the photoreceptor is uneven and not smooth, the durability against electrochemical action and mechanical external force may be reduced, and the repeat stability and environmental stability may be reduced. When the photosensitive layer is composed of two layers, a charge generation layer and a charge transport layer, the charge transport layer is usually formed on the outer surface side of the charge generation layer and is thicker than the charge generation layer. . Therefore, the induction heating step and the far infrared heating drying step are most preferably performed on the charge transport layer. Further, the method for producing a photoreceptor of the present invention is not limited to the charge generation layer and / or the charge transport layer, and can be used when forming the undercoat layer and the protective layer.

  When the solvent contained in the solvent of the coating solution is only a solvent having a relative evaporation rate of 1.7 or more and a large evaporation rate, the conductive substrate is heated by an induction heating step performed as a pre-drying step. The heat of the conductive substrate is conducted to the coating film, the coating film surface is dried and cured, and the solvent remains in the coating film even if the far-infrared heat drying process is performed. Therefore, by containing 30% by weight or more of a solvent having a relative evaporation rate of less than 1.7 and having a low evaporation rate in the solvent, the solvent inside the coating film can be efficiently removed without curing the coating film surface. It is possible to diffuse and vaporize. In addition, when such a solvent is used, the coating surface can be prevented from drying more rapidly than the inside of the coating film during the coating process and before moving from the coating process to the induction heating process. The formation of a cured film in can be prevented.

  The more preferable content of the solvent having a relative evaporation rate of less than 1.7 can be appropriately selected depending on the time used for the drying step, the kind of the solvent, and the like. The higher the content of the solvent having a relative evaporation rate of less than 1.7, the better the formation of a cured film on the coating film surface can be prevented. However, if a solvent having a relative evaporation rate of less than 1.7, such as diethylene glycol monobutyl ether, which is extremely difficult to evaporate, the evaporation rate may be too small. When such a solvent with a very low evaporation rate is contained in the solvent, it is preferable to contain a solvent with a high relative evaporation rate to some extent in order to perform drying in a short time. Table 1 shows the relative evaporation rates of typical solvents.

Next, a photosensitive layer forming material and a coating solution for forming each layer of the photosensitive layer will be described.
The charge generation layer contains, as a main component, a charge generation material that generates charges by absorbing light. Examples of charge generation materials include azo pigments such as monoazo pigments, bisazo pigments, and trisazo pigments, indigo pigments such as indigo and thioindigo, perylene pigments such as peryleneimide and perylene anhydride, and polycyclic quinones such as anthraquinone and pyrenequinone. Pigments, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, triphenylmethane pigments such as methyl violet, crystal violet, knight blue and victoria blue, acridine pigments such as erythrosin, rhodamine B, rhodamine 3R, acridine orange and frappeosin , Thiazine dyes such as methylene blue and methylene green, oxazine dyes such as capri blue and meldra blue, squarylium dyes, pyrylium salts, thiopyrylium salts Thioindigo dyes, bisbenzimidazole dyes, quinacridone dyes, quinoline dyes, lake dyes, azo lake dyes, dioxazine dyes, azurenium dyes, triallylmethane dyes, xanthene dyes, cyanine dyes, etc. Organic pigments, dyes, amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloys, cadmium sulfide, antimony sulfide, zinc oxide, zinc sulfide, and the like. These charge generation materials may be used alone or in combination of two or more.

  The charge generation layer is a coating solution for forming a charge generation layer obtained by dissolving or dispersing a charge generation material in a solvent, particularly a binder resin solution obtained by dissolving or mixing a binder resin as a binder in a solvent. Further, it is formed by applying a coating solution obtained by dispersing the charge generating material by a known method on the conductive substrate or the undercoat layer.

  Examples of the binder resin used in the charge generation layer forming coating solution include polyester resin, polystyrene resin, polyurethane resin, phenol resin, alkyd resin, melamine resin, epoxy resin, silicone resin, acrylic resin, methacrylic resin, polycarbonate resin, Use a resin selected from the group consisting of a resin such as a polyarylate resin, a phenoxy resin, a polyvinyl butyral resin, a polyvinyl formal resin, and a copolymer resin containing two or more repeating units constituting these resins. Can do. These may be used individually by 1 type and may use 2 or more types together. Examples of the copolymer resin include insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin. . The binder resin is not limited to those described above, and a commonly used known resin can be used.

  Examples of the solvent used as the solvent capable of dissolving or dispersing the charge generating material and the binder resin include 1,4-dioxane, methyl isobutyl ketone, ethanol, isopropanol, acetic acid, which are solvents having a relative evaporation rate of less than 1.7. Isobutyl, 1,3-dichloropropane, n-butyl acetate, n-propanol, xylene, isobutanol, ethylene glycol monomethyl ether, n-butanol, methyl amyl acetate, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monomethyl Ether acetate, cyclohexanone, 3-octanone, diisobutyl ketone, methylcyclohexanone, ethylene glycol monobutyl ether, isophorone, diethylene glycol monomethyl Ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether.

  Further, a solvent having a relative evaporation rate of less than 1.7 may be mixed with a solvent having a relative evaporation rate of 1.7 or more. At this time, the solvent having a relative evaporation rate of less than 1.7 is contained in the solvent by 30% by weight or more. Examples of the solvent having a relative evaporation rate of 1.7 or more include sec-butyl acetate, methanol, toluene, n-propyl acetate, trichloroethylene, isopropyl acetate, methyl ethyl ketone, benzene, ethyl acetate, 1,3-dioxolane, trichloroethane, and tetrahydrofuran. , Methyl acetate, acetone, methylene dichloride and the like.

  The blending ratio of the charge generation material and the binder resin is preferably such that the charge generation material is contained in the range of 10 wt% to 99 wt% with respect to the weight of the entire charge generation layer. If the charge generation material is less than 10% by weight, the sensitivity of the photoreceptor may be lowered. When the charge generation material exceeds 99% by weight, not only the strength of the charge generation layer is decreased, but also the dispersibility of the charge generation material is decreased and the coarse particles are increased. Therefore, image defects, particularly image fogging called black spots, in which toner adheres to a white background and minute black spots are formed, occur.

  As a pretreatment for dispersing the charge generation material in the binder resin solution, the charge generation material may be pulverized in advance by a pulverizer. Examples of the pulverizer used for the pulverization treatment include a ball mill, a paint shaker, a sand mill, an attritor, a vibration mill, and an ultrasonic disperser. As the dispersion condition at this time, it is desirable to select an appropriate condition so that impurities are not mixed due to wear of the container used and the members constituting the disperser.

  Furthermore, you may add various additives, such as a hole transport material, an electron transport material, antioxidant, a dispersion stabilizer, and a sensitizer, to a charge generation layer as needed. As a result, the potential characteristics are improved, and the stability as the coating liquid can be improved. Further, fatigue deterioration when the electrophotographic photosensitive member is repeatedly used can be reduced, and durability can be improved.

  The thickness of the charge generation layer after drying is preferably from 0.05 μm to 5 μm, and more preferably from 0.1 μm to 1 μm. If the film thickness of the charge generation layer is less than 0.05 μm, the light absorption efficiency is lowered, and the sensitivity of the photoreceptor may be lowered. If the film thickness of the charge generation layer exceeds 5 μm, charge transfer inside the charge generation layer becomes a rate-determining step in the process of erasing charges on the surface of the electrophotographic photosensitive member, and the sensitivity may be lowered.

  The charge transport layer can be obtained by including in the binder resin a charge transport material having the ability to accept and transport charges generated by the charge generation material. The charge transport layer is not limited to one layer, and may be composed of two or more layers. By using multiple layers in this way, the necessary functions of the charge transport layer can be assigned to different layers, and the width of the material is wider than in the case of a single layer. In addition, since it is almost unnecessary to consider the compatibility of various materials in the same layer, a highly functional photoreceptor can be easily provided.

  As the charge transport material, a hole transport material and an electron transport material can be used. Examples of hole transport materials include carbazole derivatives, pyrene derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, Polycyclic aromatic compounds, indole derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, triarylmethane derivatives, phenylenediamine derivatives, stilbene Derivatives, enamine derivatives, benzidine derivatives and the like. In addition, polymers having groups derived from these compounds in the main chain or side chain, such as poly-N-vinylcarbazole, poly-1-vinylpyrene, ethylcarbazole-formaldehyde resin, triphenylmethane polymer, poly-9-vinylanthracene And polysilane.

  Examples of the electron transport material include benzoquinone derivatives, tetracyanoethylene derivatives, tetracyanoquinodimethane derivatives, fluorenone derivatives, xanthone derivatives, phenanthraquinone derivatives, phthalic anhydride derivatives, diphenoquinone derivatives and other organic compounds, amorphous silicon, Examples include inorganic materials such as amorphous selenium, tellurium, selenium-tellurium alloy, cadmium sulfide, antimony sulfide, zinc oxide, and zinc sulfide. The charge transport material is not limited to those listed above, and can be used alone or in admixture of two or more.

  Similarly to the charge generation layer, the charge transport layer is obtained by dissolving or mixing a charge transport layer forming coating solution obtained by dissolving or dispersing a charge transport material in a solvent, particularly a binder resin as a binder in the solvent. In the binder resin solution obtained, a coating solution obtained by dissolving or dispersing the charge transport material by a known method is applied on the charge generation layer, preferably the induction heating step and far infrared heating drying step of the present invention. It is formed by making it dry through.

As the binder resin for the charge transport layer, a resin having excellent compatibility with the charge transport material is selected. Examples of the binder resin include vinyl polymer resins such as polymethyl methacrylate resin, polystyrene resin, and polyvinyl chloride resin, and copolymer resins thereof, polycarbonate resin, polyester resin, polyester carbonate resin, polysulfone resin, phenoxy resin, and epoxy resin. , Silicone resin, polyarylate resin, polyamide resin, methacrylic resin, acrylic resin, polyether resin, polyurethane resin, polyacrylamide resin, phenol resin, and the like. Moreover, you may use the thermosetting resin which bridge | crosslinked these resin partially. These resins may be used alone or in combination of two or more. Among the resins described above, polystyrene resin, polycarbonate resin, polyarylate resin, or polyphenylene oxide has a volume resistance of 10 ¹³ Ω or more and is excellent in electrical insulation, and is also excellent in film formability and electrical characteristics. preferable.

  The ratio (B / A) of the weight (B) of the binder resin to the weight (A) of the charge transport material is preferably 12/10 or more and 30/10 or less (= 1.2 or more and 3.0 or less). When the ratio (B / A) exceeds 30/10 (= 3.0) and the binder resin content is increased, the viscosity of the coating solution for forming a charge transport layer increases, resulting in a decrease in coating speed and productivity. May decrease significantly. Further, if the amount of the solvent in the charge transport layer forming coating solution is increased in order to suppress this increase in viscosity, a brushing phenomenon that causes white turbidity in the formed charge transport layer occurs. Further, when the ratio (B / A) is less than 12/10 (= 1.2) and the binder resin ratio is low, the printing durability is lowered and the charge transport is lower than when the binder resin ratio is high. Since the amount of wear of the layer increases, the durability life is shortened. However, when the charge transport layer is composed of multiple layers, this ratio can be arbitrarily changed according to the function of each layer.

  In order to improve the film formability, flexibility, and surface smoothness, additives such as a plasticizer and a surface modifier may be added to the charge transport layer as necessary. Examples of the plasticizer include biphenyl, biphenyl chloride, benzophenone, o-terphenyl, dibasic acid ester, fatty acid ester, phosphoric acid ester, phthalic acid ester, various fluorohydrocarbons, chlorinated paraffin, and epoxy type plasticizer. It is done. Examples of the surface modifier include silicone oil and fluororesin.

  The charge transport layer may be added with fine particles of an inorganic compound or an organic compound in order to enhance mechanical strength and improve electrical characteristics. Furthermore, you may add various additives, such as antioxidant and a light stabilizer, as needed. As a result, deterioration of the charge transport layer due to adhesion of active substances such as ozone and NOx generated during charging is reduced, and durability when the electrophotographic photosensitive member is repeatedly used can be improved. In addition, the stability as a coating liquid for forming a charge transport layer is enhanced, the life of the liquid is extended, and the durability of the electrophotographic photosensitive member produced with the coating liquid is also improved because impurities are reduced.

  As the antioxidant and the light stabilizer, hindered phenol derivatives or hindered amine derivatives are preferably used. The hindered phenol derivative is preferably used in a weight ratio in the range of 0.001 to 0.10 with respect to the weight of the charge transport material. The hindered amine derivative is preferably used in a weight ratio in the range of 0.001 to 0.10 with respect to the weight of the charge transport material. Further, a hindered phenol derivative and a hindered amine derivative may be mixed and used. In this case, the total amount of hindered phenol derivative and hindered amine derivative used is preferably a weight ratio in the range of 0.001 to 0.10 with respect to the weight of the charge transport material.

  Charge transport layer formation when the amount of hindered phenol derivative used or the amount of hindered amine derivative used or the total amount of hindered phenol derivative and hindered amine derivative used is less than 0.001 by weight with respect to the weight of the charge transport material. It is not possible to exhibit a sufficient effect for improving the stability of the coating liquid for use and improving the durability of the electrophotographic photosensitive member. On the other hand, if the weight ratio exceeds 0.10, the electrical characteristics of the photoreceptor are adversely affected.

  Examples of the solvent that can be used as a solvent that can dissolve or disperse the charge transport material and the binder resin include 1,4-dioxane, methyl isobutyl ketone, isobutyl acetate, 1, which are solvents having a relative evaporation rate of less than 1.7. Examples include 3-dichloropropane, n-butyl acetate, xylene, methyl amyl acetate, ethylene glycol monomethyl ether acetate, cyclohexanone, 3-octanone, diisobutyl ketone, methylcyclohexanone, ethylene glycol monobutyl ether, isophorone, diethylene glycol monoethyl ether, and the like.

  Further, a solvent having a relative evaporation rate of less than 1.7 may be mixed with a solvent having a relative evaporation rate of 1.7 or more. At this time, the solvent having a relative evaporation rate of less than 1.7 is contained in the solvent by 30% by weight or more. Examples of the solvent having a relative evaporation rate of 1.7 or more include sec-butyl acetate, toluene, n-propyl acetate, trichloroethylene, isopropyl acetate, methyl ethyl ketone, benzene, ethyl acetate, 1,3-dioxolane, trichloroethane, tetrahydrofuran, acetic acid. Examples include methyl, acetone, methylene dichloride and the like.

  The thickness of the charge transport layer after drying is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 40 μm or less. If the thickness of the charge transport layer is less than 5 μm, the charge holding ability on the surface of the electrophotographic photosensitive member may be lowered. If the thickness of the charge transport layer exceeds 50 μm, the resolution of the electrophotographic photoreceptor may be lowered.

  In the case of a laminated type photoreceptor, a charge transport layer may be laminated on the charge generation layer formed on the conductive substrate, and conversely, the charge generation layer on the charge transport layer formed on the conductive substrate. May be laminated. In the case of a single layer type photoreceptor, the photosensitive layer containing the charge generating material and the charge transport material is formed by the same method as that for forming the charge transport layer described above. For example, a coating solution for forming a photosensitive layer is prepared by dissolving or dispersing a charge generating material, a hole transporting material or electron transporting material that is a charge transporting material, and a binder resin in a solvent composed of the appropriate solvent described above. It is formed by applying this photosensitive layer forming coating solution by the various coating methods described above. The film thickness of the photosensitive layer of the single-layer type photoreceptor is preferably 5 μm or more and 100 μm or less after drying, and more preferably 10 μm or more and 50 μm or less. When the film thickness of the photosensitive layer is less than 5 μm, the charge holding ability of the surface of the electrophotographic photoreceptor is lowered. When the film thickness of the photosensitive layer exceeds 100 μm, productivity decreases.

  The electrophotographic photosensitive member may be provided with an undercoat layer between the conductive substrate, the charge generation layer, and the charge transport layer as described above. By providing the undercoat layer, injection of charges from the conductive substrate to the photosensitive layer can be prevented, so that the charge holding ability of the photoreceptor can be prevented from being lowered. In addition, when a photoreceptor having an undercoat layer is used for image formation, a decrease in surface charge other than a portion to be erased by exposure is suppressed, so that defects such as fogging can be prevented from occurring in an image. Furthermore, since the surface of the conductive substrate can be smoothed by covering the defects on the surface of the conductive substrate with the undercoat layer, the film forming properties of the charge generation layer and the charge transport layer can be improved. Further, peeling of the charge generation layer and the charge transport layer from the conductive substrate can be suppressed, and adhesion to the conductive substrate can be improved.

  Examples of the undercoat layer include resin layers and alumite layers made of various resin materials. The resin material that forms the resin layer is polyethylene resin, polypropylene resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, polycarbonate resin, polyester carbonate resin, polysulfone. Resins, phenoxy resins, polyarylate resins, silicone resins, polyvinyl butyral resins, polyamide resins and the like, copolymer resins containing two or more repeating units constituting these resins, casein, gelatin, polyvinyl alcohol, Examples thereof include ethyl cellulose.

  The undercoat layer may contain particles such as a metal oxide. By containing these particles, the volume resistance value of the undercoat layer can be adjusted to further suppress charge injection from the conductive substrate to the photosensitive layer, and even if there is a change in temperature, humidity, etc. The electrical characteristics of the photographic photoreceptor can be maintained. Examples of the metal oxide particles include titanium oxide, aluminum oxide, aluminum hydroxide, and tin oxide particles. When particles such as metal oxide are contained in the undercoat layer, for example, a coating solution for forming the undercoat layer is prepared by dispersing these particles in a resin solution in which the above-described resin is dissolved. An undercoat layer is formed by coating on a conductive substrate.

  Examples of the solvent used as the solvent for the resin liquid include, in addition to the organic solvent used for the charge generation layer or charge transport layer coating liquid described above, for example, a solvent having a relative evaporation rate of less than 1.7. , 4-dioxane, methyl isobutyl ketone, ethanol, isopropanol, isobutyl acetate, 1,3-dichloropropane, n-butyl acetate, n-propanol, xylene, isobutanol, ethylene glycol monomethyl ether, n-butanol, methyl amyl acetate, water , Ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monomethyl ether acetate, cyclohexanone, 3-octanone, diisobutyl ketone, methylcyclohexanone, ethylene glycol monobutyl ether, isophor Emissions, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether.

  Further, a solvent having a relative evaporation rate of less than 1.7 may be mixed with a solvent having a relative evaporation rate of 1.7 or more. At this time, the solvent having a relative evaporation rate of less than 1.7 is contained in the solvent by 30% by weight or more. Examples of the solvent having a relative evaporation rate of 1.7 or more include sec-butyl acetate, methanol, toluene, n-propyl acetate, trichloroethylene, isopropyl acetate, methyl ethyl ketone, benzene, ethyl acetate, 1,3-dioxolane, trichloroethane, and tetrahydrofuran. , Methyl acetate, acetone, methylene dichloride and the like.

  As a method for dispersing the metal oxide particles in the resin solution, a general method using a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, or the like can be used.

  When the weight of the total content of the resin and the metal oxide in the coating solution for forming the undercoat layer is C and the weight of the content of the solvent in the coating solution for forming the undercoat layer is D, the content of the solvent The ratio (C / D) of the total content C of the resin and metal oxide to D is preferably 1/99 or more and 40/60 or less (= 0.01 or more and 0.67 or less), more preferably 2/98 or more and 30/70 or less (= 0.02 or more and 0.43 or less).

  The ratio (E / F) of the resin content (weight E) to the metal oxide content (weight F) in the coating solution for forming the undercoat layer is 1/99 or more and 90/10 or less (= 0.01 or more). 9.0 or less), more preferably 5/95 or more and 70/30 or less (= 0.05 or more and 2.33 or less).

  The thickness of the undercoat layer after drying is preferably 0.01 μm or more and 20 μm or less, and more preferably 0.1 μm or more and 10 μm or less. When the film thickness of the undercoat layer is less than 0.01 μm, it does not substantially function as the undercoat layer, and a uniform surface cannot be obtained by covering defects of the conductive substrate. Further, since it becomes impossible to prevent the injection of charges from the conductive substrate to the photosensitive layer, the chargeability of the photosensitive layer is lowered. If the thickness of the undercoat layer exceeds 20 μm, it is difficult to form the undercoat layer uniformly, and the sensitivity of the electrophotographic photosensitive member is lowered, which is not preferable.

  A protective layer may be provided on the outer periphery of the charge generation layer and the charge transport layer. By providing a protective layer, it is possible to improve the wear life of the electrophotographic photosensitive member, and electrochemically apply to the photosensitive layer such as ozone and NOx generated by corona discharge when the surface of the electrophotographic photosensitive member is charged. Durability to action can be improved.

  As the protective layer, for example, a layer made of a curable resin, an inorganic filler-containing resin, an inorganic oxide, or the like is used. Examples of the resin used for the protective layer include acrylonitrile-butadiene-styrene resin, acrylonitrile-chlorinated polyethylene-styrene resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, and polyamide. Polyamideimide, polyacrylate, polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, acrylonitrile-styrene resin , Butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, epoxy resin Include resins, such as.

  Examples of the filler added to the protective layer include titanium oxide, tin oxide, zinc oxide, zirconium oxide, indium oxide, silicon nitride, calcium oxide, barium sulfate, indium-tin oxide (ITO), silica, colloidal silica, Alumina, carbon black, fluorine resin fine powder, polysiloxane resin fine powder, polymer charge transport material fine powder and the like can be mentioned. These may be used alone or in combination of two or more. These fillers may be surface-treated with an inorganic substance or an organic substance for reasons such as improving dispersibility and modifying surface properties. Among these surface treatments, the water-repellent treated fillers include those treated with a silane coupling agent, those treated with a fluorinated silane coupling agent, those treated with higher fatty acids, and polymer materials. Etc. Moreover, as what was processed with the inorganic substance, what processed the filler surface with an alumina, a zirconia, a tin oxide, a silica etc. is mentioned, for example.

  In addition, a hole transport material or an electron transport material which is the above-described charge transport material may be added to the protective layer for the purpose of efficiently transporting holes or electrons. In addition, for the purpose of improving charging properties, a phenol compound, a hydroquinone compound, a hindered phenol compound, a hindered amine compound, a compound in which hindered amine and hindered phenol are present in the same molecule, and the like can be added. Further, a plasticizer and / or a leveling agent may be added. As a plasticizer, what is generally used as a plasticizer of resin, such as dibutyl phthalate and dioctyl phthalate, can be used, for example. The amount of the plasticizer used is suitably 0.1% by weight or more and 30% by weight or less based on the resin. As the leveling agent, for example, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers having a perfluoroalkyl group in the side chain, oligomers and the like can be used. The amount of the leveling agent used is suitably 0.001% by weight or more and 1% by weight or less based on the resin.

  In order to form the protective layer with a layer containing at least a curable resin, various crosslinking reactions known in the field of materials, for example, radical polymerization, ionic polymerization, thermal polymerization, photopolymerization, radiation polymerization, etc. are used. be able to. In order to realize a cured protective layer having a low surface energy, a material having a silicone structure, a perfluoroalkyl structure, a long-chain alkyl structure, or the like may be subjected to a crosslinking reaction by a known method.

  As described above, in order to provide the protective layer with a charge transport function, a substance having a charge transport function or a polymer charge transport substance may be subjected to a crosslinking reaction. As such a protective layer, for example, a layer made of a polysiloxane resin obtained by mixing and curing a crosslinkable organopolysiloxane resin and a compound containing a structural unit capable of binding to it and having a charge transporting property is used. A protective layer having excellent durability and electrical characteristics can be realized.

  The protective layer is prepared by dissolving or dispersing the resin and, if necessary, additives such as the filler in a solvent composed of a suitable solvent to prepare a coating solution for forming a protective layer, and using this coating solution as a charge transport layer or the like. It is formed by coating on and drying.

  Examples of the solvent used as the solvent for the protective layer forming coating solution include 1,4-dioxane, methyl isobutyl ketone, ethanol, isopropanol, isobutyl acetate, 1,3, which are solvents having a relative evaporation rate of less than 1.7. -Dichloropropane, n-butyl acetate, n-propanol, xylene, isobutanol, ethylene glycol monomethyl ether, n-butanol, methyl amyl acetate, water, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monomethyl ether acetate, Cyclohexanone, 3-octanone, diisobutyl ketone, methylcyclohexanone, ethylene glycol monobutyl ether, isophorone, diethylene glycol monomethyl ether, diethylene glycol Monoethyl ether, diethylene glycol monoethyl ether.

  Further, a solvent having a relative evaporation rate of less than 1.7 may be mixed with a solvent having a relative evaporation rate of 1.7 or more. At this time, the solvent having a relative evaporation rate of less than 1.7 is contained in the solvent by 30% by weight or more. Examples of the solvent having a relative evaporation rate of 1.7 or more include sec-butyl acetate, methanol, toluene, n-propyl acetate, trichloroethylene, isopropyl acetate, methyl ethyl ketone, benzene, ethyl acetate, 1,3-dioxolane, cyclohexane, trichloroethane. , Tetrahydrofuran, methyl acetate, acetone, methylene dichloride and the like. Among these, those containing at least one of water, alcohols such as methanol, ethanol and n-butanol and glyme solvents such as ethylene glycol monobutyl ether and diethylene glycol monobutyl ether are preferable.

  In addition, when the protective layer forming material and the lower layer forming material provided under the protective layer are soluble in the same solvent, the protective layer formed as a layer farther from the conductive substrate is formed by the roll coating method. Preferably it is applied on top.

  The thickness of the protective layer after drying is preferably 0.5 μm or more and 5 μm or less, and more preferably 1 μm or more and 3 μm or less. When the thickness of the protective layer is less than 0.5 μm, the protective layer easily peels off from the interface with the lower layer when subjected to external force due to contact with the blade or the charging roller. This is because, when the protective layer is thin, when the external force is applied, the protective layer itself is not fully resisted and a force is constantly applied to the interface with the lower layer, and if it is applied over a long period of time, the applied force is applied to the interface. This is considered to be because the shift tends to occur. If the protective layer is thin, all the protective layer may be lost before the lifetime of the electrophotographic photosensitive member due to wear. If the thickness of the protective layer is greater than 5 μm, the carrier diffuses in the process of moving through the protective layer, so that character thickening or the like is likely to occur, and there is a risk that the sensitivity of the photoreceptor is lowered and the residual potential is increased due to repetition. .

  As described above, the antioxidant and / or the light stabilizer used as necessary in the charge transport layer may be contained in any one of the charge generation layer, the charge transport layer, and the protective layer. It may be contained in all.

  When the coating process for coating the photosensitive layer 5 as described above is applied to the conductive gas 5 and the coating film 6 is formed on the conductive substrate 5, the coating is immediately placed in the drying apparatus 1 and the induction heating process. And subjected to a far infrared heat drying process.

  Next, the induction heating process and the far infrared heating drying process, which are the features of the present invention, will be described. In the induction heating step, the conductive substrate 5 disposed immediately above the induction heating unit 2 is heated to 60 ° C. or more and 150 ° C. or less by the induction heating unit 2. If the temperature at which the conductive substrate 5 is heated is less than 60 ° C., the temperature of the conductive substrate 5 is low, and even if the coating film 6 is heated in the initial stage of the far-infrared heating drying process described later, Heat is conducted to the conductive substrate 5, and the conducted heat is released from the conductive substrate 5 to the outside, resulting in a reduction in heating efficiency. On the other hand, if the temperature exceeds 150 ° C., the coating film 6 may be heated to a temperature higher than the heat resistant temperature of the photosensitive layer forming material.

  The conductive substrate 5 to be heated by the induction heating means 2 is heated to 60 ° C. or more and 150 ° C. or less, but the solvent having the lowest boiling point among the solvents constituting the coating solution for forming the coating film 6 is used. Heating to a temperature lower than the boiling point is preferred. When heated at a temperature higher than the boiling point of the solvent that forms the coating film 6, the coating film 6 begins to dry during the induction heating step and hardens, and a cured film may be formed on the surface of the coating film 6.

  For example, when an aluminum cylindrical conductive substrate having a thickness of about 1 mm is used as the conductive substrate 5 and the conductive substrate 5 is uniformly heated, a low to high frequency oscillation frequency of 50 Hz (commercial frequency) to 250 kHz is used. Inductive heating is preferable from the viewpoint of heating efficiency, and induction heating at a low frequency of 50 Hz (commercial frequency) to 1 kHz is most preferable from the viewpoint of uniformly heating the entire conductive substrate.

  Moreover, it is preferable that the time which heats with the induction heating means 2 is about 0.5 to 60 second. If the heating time is less than 0.5 seconds, it is difficult to bring the conductive substrate 5 to a desired temperature. Even if the heating time exceeds 60 seconds, there is no particular problem. However, since the production efficiency is lowered, the heating time is preferably 60 seconds or less.

  In the induction heating step, the conductive substrate 5 is rotated around the axis by the rotating means 7. When the conductive substrate 5 is heated in the induction heating step, the temperature of the coating film 6 rises as the temperature of the conductive substrate 5 rises, the viscosity of the coating film 6 decreases, and the fluidity increases. When the fluidity of the coating film 6 increases, the coating film 6 hangs down in the direction of gravity through the conductive substrate 5, and the film thickness in the circumferential direction of the conductive substrate 5 becomes non-uniform. By holding the conductive substrate 5 so that the axial direction is parallel to the horizontal direction and rotating around the axial line, the influence of gravity on the coating film 6 can be made uniform, and the film thickness in the circumferential direction can be made uniform. Can be dried.

  Here, the rotational speed of the conductive substrate 5 by the rotating means 7 is preferably 1 rpm or more and 500 rpm or less, more preferably 5 rpm or more and 200 rpm or less. When the rotational speed of the conductive substrate 5 is less than 1 rpm, the coating film 6 formed on the surface of the conductive substrate 5 is dripped in the direction of gravity and dried as it is, and unevenness in the thickness of the coating film 6 after drying occurs. When the rotational speed of the conductive substrate 5 exceeds 500 rpm, the coating film 6 is scattered by centrifugal force.

  When the temperature of the conductive substrate 5 heated by the induction heating step reaches a predetermined temperature, the control unit controls the operation of the moving unit according to the temperature detection output, and the conductive substrate 5 moves immediately below the far-infrared heating unit 4. And subjected to a far infrared heating drying process.

  In the far infrared heating and drying step, the coating 6 formed on the surface of the conductive substrate 5 is heated by the far infrared heating means 3 and dried. In the far-infrared heat drying step, the temperature of the coating film 6 was increased to a temperature suitable for drying the coating film 6 (a temperature lower than the heat resistance temperature of the photoconductor and not higher than the boiling point of the solvent and as high as possible). Thereafter, the temperature is maintained and the solvent is evaporated.

  As a far infrared ray irradiated to the coating film 6, a thing with a wavelength of 4-1000 micrometers can be used. Moreover, when the solvent in the coating film 6 is an organic compound, it is preferable that far infrared rays have the maximum energy in a wavelength range of 4 to 25 μm where the absorption rate into the solvent is high.

  In the initial stage of drying, the heating output from the far-infrared heating means 3 is consumed for increasing the temperature of the coating film 6 due to the heat capacity of the coating film 6. Therefore, in the initial stage of drying, the temperature of the coating film 6 can be raised in a short time by increasing the heating output from the far-infrared heating means 3.

  Here, if the heating output in this initial stage is kept as it is, the temperature of the coating film 6 will always rise. In the middle stage of drying, the temperature of the coating film 6 is higher than the heat resistance temperature of the photoreceptor or the coating film. 6 may exceed the boiling point of the solvent in 6. If the coating film 6 is heated to a temperature higher than the heat resistance temperature of the photoconductor, problems such as ineffectiveness of the charge generating material having a low heat resistance temperature occur, and the electrical characteristics of the photoconductor deteriorate. Further, when the temperature of the coating film 6 rises beyond the boiling point of the solvent in the coating film 6, the solvent generates a large amount of bubbles, resulting in bubbles and uneven thickness on the surface of the coating film 6. Therefore, the control means controls the operation of the far-infrared heating means 3 according to the temperature detection output. When the temperature of the coating film 6 reaches a predetermined temperature, the heating from the far-infrared heating means 3 is prevented so that the temperature does not become higher. The output is controlled to be smaller than the initial stage.

  Further, when the far-infrared heat drying process is performed while blowing gas from the blower nozzle 4 to the coating film 6 on the conductive substrate 5, the solvent vapor from the coating film 6 can be efficiently released to the outside. It is preferable because drying can be performed and unevenness in thickness can be prevented from occurring on the surface.

  The temperature of the gas ejected from the blow nozzle 4 is preferably 50 ° C. or higher and 130 ° C. or lower. When the temperature of the gas is less than 50 ° C., the coating film 6 is cooled in reverse, so that drying in a short time becomes difficult. If the heating output from the far-infrared heating means 3 is increased in order to dry the coating film 6 in a short time while spraying such a low-temperature gas, the conductive substrate 5 is heated in the induction heating step. Therefore, even if the surface of the coating film 6 has an appropriate temperature, the temperature inside the coating film 6 may increase excessively. When the internal temperature rises too much and the heating is performed exceeding the boiling point of the solvent in the coating film 6, a large amount of bubbles are generated, and the thickness of the coating film 6 is uneven. In addition, when heating is performed at a temperature equal to or higher than the heat-resistant temperature of the photosensitive layer forming material, the properties of the charge generating substance are deteriorated, and the electrical characteristics as the photoreceptor are deteriorated.

  On the other hand, when the temperature of the gas exceeds 130 ° C., drying is performed by hot air, and the surface of the coating film 6 is dried and cured before the solvent in the coating film 6 evaporates. May remain. Moreover, when the coating film 6 is heated in this gas by the far-infrared heating means 3, the temperature of the coating film 6 becomes too high, and the same problem as when the temperature inside the coating film 6 rises too much occurs.

  The flow rate of the gas supplied from the blowing nozzle 4 is preferably 1 m / min or more and 100 m / min or less, and more preferably 5 m / min or more and 50 m / min or less. When the flow rate is less than 1 m / min, the amount of gas supplied to the conductive substrate 5 is small, and it becomes difficult to control the temperature and discharge the solvent in the vaporized coating film 6. When the flow rate exceeds 100 m / min, the shape of the undried coating film 6 is changed by the force of the gas, and the coating film 6 after drying, that is, the photosensitive layer may be uneven.

The flow rate of the gas supplied from the blower nozzle 4 is preferably 0.1 m ³ / min or more ^{10 m} 3 / min or less in order to discharge the solvent in the coating film 6 temperature control and vaporization. If the flow rate is less than 0.1 m ³ / min, the amount of gas supplied to the conductive substrate 5 is small, and it may be difficult to control the temperature and discharge the solvent in the vaporized coating film 6. If the flow rate exceeds 10 m ³ / min, the temperature of the coating film 6 may not easily rise due to the cooling effect of the gas.

  When the drying apparatus 1 having such a blowing nozzle 4 is used, the far infrared heating drying process can be performed in a gas having a gas temperature of 50 ° C. or higher and 130 ° C. or lower and higher than normal temperature. The temperature rise can be accelerated and the drying can be performed in a short time.

  It is preferable that the temperature and flow rate of the gas are also adjusted in the initial stage and the intermediate stage of the drying nozzle 4 as well. For example, in the initial stage of drying, the temperature of the gas supplied from the blower nozzle 4 to the coating film 6 is increased and the flow rate is increased. As a result, the temperature of the atmosphere for drying the coating film 6 is increased, and the time required for the temperature increase of the coating film 6 is shortened. In the middle of drying, the temperature of the atmosphere is lowered by lowering the temperature of the gas supplied from the blower nozzle 4 to the coating film 6, and the gas flow rate is appropriately adjusted according to the degree of the temperature of the gas to coat the coating film. 6. Prevents temperature rise more than necessary.

  The gas flow rate in the middle of drying needs to be adjusted in consideration of the gas temperature and the temperature of the coating film 6. The control means controls the operation of the blower nozzle 4 according to the temperature detection output. For example, when the temperature of the coating film 6 is higher than the temperature of the gas, the temperature increase of the coating film 6 is promoted by increasing the gas flow rate, and the temperature increase can be moderated by decreasing the flow rate. it can. When the temperature of the coating film 6 is lower than the temperature of the gas, the temperature of the coating film 6 can be decreased by increasing the gas flow rate, and the temperature decrease can be moderated by decreasing the flow rate. .

  In the middle stage of drying, the drying of the solvent in the coating film 6 proceeds and the amount of the solvent remaining in the coating film 6 decreases, so that the heat of vaporization required to vaporize the solvent also decreases. Considering this, it is preferable to further reduce the heating output of the far-infrared heating means 3 and further lower the temperature of the gas supplied to the coating film 6 from the blower nozzle 4.

  In addition, the conductive substrate 5 rotates around the axis during the far-infrared heating drying process as in the induction heating process. This prevents unevenness of the thickness of the coating film 6 after drying due to dripping of the coating film 6, and also prevents uneven heating of the conductive substrate 5 due to the fact that the portion not irradiated with far infrared rays is not heated. The entire substrate 5 can be heated uniformly.

  According to the method for producing an electrophotographic photosensitive member of the present invention, an induction heating step is performed as a pre-step of the far infrared heating drying step, and the conductive substrate 5 is preheated. In the stage, it is possible to prevent the heat conducted from the lower part of the coating film 6 from being released from the conductive substrate 5 to the outside. Thereby, since the temperature drop of the coating film 6 due to heat radiation from the conductive substrate 5 can be prevented, the coating film 6 can be dried in a short time.

  Moreover, since the far-infrared heating means 3 can heat the solvent inside the coating film 6 and can dry the coating film 6 from the inside, it is possible to prevent a cured film from being formed on the surface of the coating film 6. As a result, pinholes, bubbles, uneven surface thickness, and the like are prevented from occurring in the coating film 6 as the photosensitive layer of the photoreceptor, and a smooth photosensitive layer can be formed. Further, since the amount of the solvent remaining in the coating film 6 after drying can be reduced, it is possible to prevent the electrical characteristics of the electrophotographic photosensitive member from being deteriorated.

  The drying apparatus 1 that realizes the method for producing a photoreceptor of the present invention is not limited to the above configuration, and various modifications can be made.

  The induction heating means 2 of the drying apparatus 1 is a flat induction coil in this embodiment, but in order to uniformly heat the conductive substrate 5, it enters and exits the inside of the hollow cylindrical conductive substrate 5. The structure arrange | positioned freely, the structure provided so that the circumference | surroundings of the cylindrical conductive base | substrate 5 may be covered may be sufficient.

  The reflecting plate provided on the side opposite to the side facing the far-infrared heating means 3 of the conductive substrate 5 is for improving the heating efficiency, and thus does not necessarily need to be provided.

  The photoreceptor manufactured by the method of the present invention is not limited to the cylindrical shape of the conductive substrate, but may be a columnar shape, a sheet shape, or the like. When the conductive substrate is in the form of a sheet, for example, it is placed on a movable stage in a horizontal plane, the conductive substrate is heated by induction heating, the stage is moved, and the coating film is heated by far infrared rays and dried. be able to.

  FIG. 2 is a side view schematically showing the configuration of the drying apparatus 11 for carrying out the induction heating step and the far-infrared heating drying step in the method for producing a photoreceptor of the present invention. The method for producing an electrophotographic photoreceptor of the present invention may be performed as a continuous production process using a drying apparatus 11 as shown in FIG. Such a drying apparatus 11 is optimal when applied to mass production of a photoreceptor. The three-dimensional XYZ axis shown in FIG. 2 is defined as follows. The direction constituting the horizontal plane is the XY direction, the axial direction of the conductive substrate 12 is the Y direction, and the moving direction of the conductive substrate 12 orthogonal to the Y direction is the X direction. A vertical direction perpendicular to the XY direction is taken as a Z direction.

  The drying apparatus 11 includes a pair of base substrates 14a and 14b that extend in the X-axis direction and are spaced apart from each other in the Z direction, and a pair of plate-shaped induction heating means 15a and 15b that are respectively provided on the base substrates 14a and 14b. , Provided between a plurality of pairs of far infrared heating means 16a, 16b provided on the base substrates 14a, 14b, a blower nozzle 17a provided between the plurality of far infrared heating means 16a, and a plurality of far infrared heating means 16b, respectively. The blower nozzle 17b, the rotation base means (not shown) that conveys the pair of base substrates 14a and 14b at a constant speed in the X-axis direction while rotating the conductive substrate 12 in the axial direction, and the operation of the entire apparatus are controlled. Control means.

  The induction heating means 15a and 15b, the far-infrared heating means 16a and 16b, and the blower nozzles 17a and 17b are provided facing each other in the Z-axis direction. Hereinafter, except for the case where a specific induction heating means, far infrared heating means or blower nozzle is designated and described, the alphabet is omitted and referred to as induction heating means 15, far infrared heating means 16 and blower nozzle 17. The induction heating means 15, far infrared heating means 16 and blower nozzle 17 have the same configuration as the induction heating means 2, far infrared heating means 3 and blower nozzle 4 provided in the above-described drying apparatus 1, respectively. Is omitted.

  The rotational movement means holds the cylindrical conductive base 12 so that the axial direction is parallel to the horizontal direction, and rotates the conductive base 12 around the axial line between the pair of base substrates 14a and 14b in the X-axis direction. At a constant speed.

  In such a drying apparatus 11, the conductive substrate 12 on which the coating film 13 is formed passes between the induction heating means 15 provided on the pair of base substrates 14a and 14b at a constant speed while rotating around the axis. Then, it passes between the far infrared heating means 16 and the blower nozzle 17. As a result, an induction heating step of raising the conductive substrate 12 to a suitable temperature while passing between the induction heating means 15 is performed. The conductive substrate 12 is moved between the far-infrared heating means 16 and the blower nozzle 17. Further, a far-infrared heating drying process for drying the coating film 13 formed on the conductive substrate 12 is performed while passing between the far-infrared heating means 16 and the blower nozzle 17. When such a drying apparatus 11 is used, the coating film 13 formed on the plurality of conductive substrates 12 can be continuously dried in a short time, so that the production efficiency is improved.

  In addition, the heating output of the induction heating unit 15 is controlled so that the conductive substrate 12 rises to a suitable temperature while the conductive substrate 12 moving at a constant speed passes between the induction heating units 15. It is preferable.

  In addition, it is preferable that the plurality of far-infrared heating means 16 and the blowing nozzles 17 be provided alternately from the viewpoint of facilitating temperature control of the coating film 13. Furthermore, from the vicinity of the induction heating means 15 to the outlet is divided into several units composed of a plurality of far-infrared heating means 16 and blower nozzles 17, and the heating output of the far-infrared heating means 16 and the blower nozzles 17 for each unit. It is preferable to control the condition of the gas to be ejected to an optimum condition.

  For example, in the unit from the position of the far infrared heating means 16 closest to the induction heating means 15 to the position where the temperature of the coating film 13 becomes a suitable temperature, the heating output from the far infrared heating means 16 is increased and The temperature of the gas supplied from the nozzle 17 is increased to accelerate the temperature rise of the coating film 13, and the coating film 13 is dried in a short time. On the other hand, in the unit near the exit from the position where the temperature of the coating film 13 becomes a suitable temperature, the heating output from the far-infrared heating means 16 is reduced, the temperature of the gas supplied from the blower nozzle 17 is lowered, and the coating film The temperature of 13 should not be raised too much. As a result, drying can be completed in a short time, and the outputs of the far-infrared heating means 16 and the blowing nozzles 17 that are provided need to be individually controlled so that the temperature of the coating film 13 does not rise too much. Does not occur.

  Hereinafter, the conductive substrate of the photoreceptor that can be produced by the production method of the present invention, the photosensitive layer forming material for forming each layer of the photosensitive layer, and the coating solution will be described.

Examples of the present invention will be described below.
Example 1
10 parts by weight of a charge transport material represented by the following structural formula (2), which is a charge transport material, and triphenylamine dimer (abbreviation: TPD: internal standard material) represented by the following structural formula (3) 0.1 A charge transport layer is formed by dissolving parts by weight and 18 parts by weight of polycarbonate resin (Iupilon Z400, manufactured by Mitsubishi Engineering Plastics) as binder resin in 112 parts by weight of cyclohexanone having a relative evaporation rate of less than 1.7. A coating solution was prepared. A wire bar is applied to the surface of the thermocouple mounting side of a 0.5 mm thick aluminum substrate on which a sheet couple thermocouple (C060-T; manufactured by Chino Corporation) is mounted. A coating film sample was obtained by coating with a thickness of 20 μm.

The obtained coating film sample is immediately placed immediately above the coil of an induction heating device (manufactured by Kyodo Denki Kogyo Co., Ltd.) and heated at an oscillation frequency of 60 Hz and an output of 300 W for 5.0 seconds to raise the substrate temperature to 135 ° C. It was. Immediately after that, a far-infrared ray having a maximum energy at a wavelength of 4.5 μm is radiated at 10 cm directly below a ceramic heater (SEG-EX type, manufactured by Futaba Kagaku Co., Ltd.) having a heater temperature of 240 ° C., and a temperature of 80 ° C. and a flow rate of 10 m. A gas having a flow rate of 0.5 m ³ / min was uniformly supplied to the coating film sample, and the coating film sample was dried by far-infrared heating for 10 minutes to prepare a coating film-coated substrate.

(Example 2)
The coating-coated substrate of Example 2 was produced in the same manner as in Example 1 except that the output of the induction heating apparatus was 150 W and the substrate temperature was increased to 61 ° C. by heating for 3.0 seconds.

(Example 3)
As a solvent for the coating liquid for forming a charge transport layer, 72 parts by weight of toluene having a relative evaporation rate of 1.7 or more and 40 parts by weight of cyclohexanone having a relative evaporation rate of less than 1.7 (36% by weight of cyclohexanone in the solvent) The coating film of Example 3 was used in the same manner as in Example 1 except that the output of the induction heating apparatus was 300 W and the substrate temperature was increased to 109 ° C. by heating for 4.0 seconds. A coated substrate was prepared.

(Comparative Example 1)
A coating-coated substrate of Comparative Example 1 was produced in the same manner as in Example 1 except that the induction heating step of heating the substrate with an induction heating device was not performed.

(Comparative Example 2)
A coated substrate of Comparative Example 2 was produced in the same manner as in Example 1 except that the output of the induction heating device was 150 W and the substrate temperature was raised to 49 ° C. by heating for 2.0 seconds.

(Comparative Example 3)
A coating film-coated substrate of Comparative Example 3 was produced in the same manner as in Example 1 except that the coating film was dried in a 130 ° C. hot air drying furnace.

(Comparative Example 4)
As a solvent for the coating solution for forming the charge transport layer, 84 parts by weight of toluene having a relative evaporation rate of 1.7 or more and 28 parts by weight of cyclohexanone having a relative evaporation rate of less than 1.7 (25% by weight of cyclohexanone in the solvent) The coating film of Comparative Example 4 was used in the same manner as in Example 1 except that the output of the induction heating apparatus was 300 W and the substrate temperature was increased to 109 ° C. by heating for 4.0 seconds. A coated substrate was prepared.

(Comparative Example 5)
As a solvent for the coating solution for forming the charge transport layer, 112 parts by weight of tetrahydrofuran having a relative evaporation rate of 1.7 or more is used. The output of the induction heating device is 150 W, and the substrate temperature is increased to 68 ° C. by heating for 4.0 seconds. A coating film-coated substrate of Comparative Example 5 was produced in the same manner as in Example 1 except that the film was raised.

[Evaluation 1]
FIG. 3 is a graph showing the results of measuring the change with time of the coating film temperature in the induction heating process and the far infrared heating drying process of Examples 1 and 2 and Comparative Examples 1 to 3. The change with time in the coating film temperature shown in FIG. 3 is as follows. For Examples 1 and 2 and Comparative Examples 2 and 3, the starting point is when the coating process is completed and induction heating is started. The substrate was placed directly below the ceramic heater, and the temperature change for 0 to 5 minutes (0 to 300 seconds) was measured with a sheet couple thermocouple, starting from when far infrared heating was started.

  In addition, a part of the coating film samples of Examples 1 to 3 and Comparative Examples 1 to 4 were cut out, the coating film constituents were extracted with acetone, and the extract was subjected to a high performance liquid chromatography apparatus (Agilent 1100 series, Yokogawa Analytical). The amount of residual solvent was determined by TPD as an internal standard substance.

  Table 2 shows the measurement results of the substrate temperature after the induction heating step, the drying method, the state of the coating film obtained after the far infrared heating drying step, and the amount of solvent remaining in the coating film in the examples and comparative examples. The residual solvent amount is the ratio of the weight of the residual solvent to the weight of the solid content (charge transport material and binder resin) in the coating film.

  According to the change with time of the coating film temperature shown in FIG. 3, when the substrate is preheated by induction heating before the coating film is dried by far infrared rays as in Examples 1 and 2, the substrate is induced. The temperature of the coating film could be raised in a shorter time than the coating film formed on the coating film-coated substrate of Comparative Example 1 that was not heated by heating, and the coating film could be dried in a short time. Moreover, in the coating-coating base | substrate of Example 1 and 2, there was little residual solvent amount after drying for 10 minutes, the surface of the coating film was smooth, and it was in the favorable state.

  However, as shown in Comparative Example 2, even when the substrate was preheated by induction heating and then the coating film was dried by far-infrared heating, the temperature of the substrate was less than 60 ° C. The change over time was the same as the change over time in the coating temperature of Comparative Example 1 in which the substrate was not heated by induction heating. In addition, the amount of residual solvent after drying for 10 minutes could not be reduced.

  In the coating film-coated substrate of Comparative Example 3 in which the substrate was preheated by induction heating and then the coating film was dried by hot air drying, a cured film was formed on the coating film surface, and the coating film surface was smooth and in a good state. However, due to the presence of the cured film, the solvent present inside the coating film could not be evaporated and the amount of residual solvent increased.

  Further, in the coating film-coated substrate of Example 3 in which cyclohexanone having a low relative evaporation rate was contained in the solvent at 30% by weight or more, the coating film could be almost dried in about 10 minutes. On the other hand, the coating film-coated substrate of Comparative Example 4 containing less than 30% by weight of cyclohexanone having a relative evaporation rate of less than 1.7 was cured by curing the coating surface before drying inside the coating film was completed. Since a film was formed and the solvent inside the coating became difficult to evaporate, a large amount of residual solvent was detected. In addition, the occurrence of a large amount of bubbles and cracks was confirmed by raising the temperature of the coating film in a short time.

  In the coating film-coated substrate of Comparative Example 5 in which only toluene having a large relative evaporation rate of 1.7 or more was used as a solvent, the coating film already started to dry before charging into the induction heating apparatus, Even when touched with a finger, there was almost no trace and the fluidity was not present. The coating film after drying for 10 minutes had a large amount of bubbles and cracks on the surface.

Example 4
An aluminum cylindrical conductive substrate having an outer diameter of 40 mm, a wall thickness of 1 mm, and a length of 340 mm was prepared, and each layer was applied and formed as follows.

a: Undercoat layer 21 parts by weight of titanium oxide (TTO55A, manufactured by Ishihara Sangyo Co., Ltd.) and 39 parts by weight of copolymer nylon resin (Amilan CM8000, manufactured by Toray Industries, Inc.), 329 parts by weight of methanol and 1,3-dioxolane 611 In addition to the mixed solvent with parts by weight, the coating solution for forming the undercoat layer was prepared by dispersing for 8 hours using a paint shaker. An undercoat layer having a film thickness of 1.0 μm is formed by a dip coating method in which the coating solution for forming the undercoat layer is filled in a coating tank and the conductive substrate is immersed in the coating tank and then pulled up. After being allowed to stand, the next charge generation layer was applied.

b: Charge generation layer As a charge generation material, an X-ray diffraction spectrum by Cu-Kα characteristic X-ray (wavelength: 1.54Å) has a clear diffraction peak at least at a Bragg angle 2θ (error: ± 0.2 °) 27.2 ° 2 parts by weight of oxotitanium phthalocyanine having a crystal structure showing 1 part by weight of polyvinyl butyral resin (S-REC BM-S, manufactured by Sekisui Chemical Co., Ltd.) and 97 parts by weight of methyl ethyl ketone are dispersed in a paint shaker. It processed and the coating liquid for charge generation layer formation was prepared. By applying this coating solution for forming a charge generation layer on the undercoat layer by the same dip coating method as that for the undercoat layer, a charge generation layer having a thickness of 0.4 μm was formed on the undercoat layer. . After standing at room temperature for 1 hour, the next charge transport layer was applied. Here, the Bragg angle 2θ is an angle formed by incident X-rays and diffracted X-rays, and represents a so-called diffraction angle.

c: Charge transport layer 10 parts by weight of the charge transport material represented by the structural formula (2), which is a charge transport material, and 0.1 part by weight of triphenylamine dimer (abbreviation: TPD) represented by the structural formula (3) And 18 parts by weight of a polycarbonate resin (Iupilon Z300, manufactured by Mitsubishi Engineering Plastics) as a binder resin, and 0.5 parts by weight of 2,6-di-t-butyl-4-methylphenol (abbreviation: BHT) Was dissolved in 130 parts by weight of cyclohexanone having a relative evaporation rate of less than 1.7 to prepare a coating solution for forming a charge transport layer. The obtained charge transport layer forming coating solution was applied onto the charge generation layer by a roll coating method to form a coating film.

Immediately after application of the coating liquid for forming the charge transport layer, the conductive substrate is placed immediately above the coil of the induction heating device (manufactured by Kyodo Denki Kogyo Co., Ltd.) and rotated at a rotation speed of 10 rpm with an oscillation frequency of 60 Hz and an output of 300 W. The induction heating process was performed by heating for 10.0 seconds and raising the temperature of the conductive substrate to 132 ° C. Immediately after that, the conductive substrate is placed 10 cm directly below a ceramic heater (SEG-EX type, manufactured by Futaba Kagaku Co., Ltd.) having a heater temperature of 260 ° C., and far infrared rays having a maximum energy at a wavelength of 4.5 μm are emitted. Charge transport formed on the surface of the conductive substrate by uniformly supplying a gas at a temperature of 100 ° C., a flow rate of 20 m / min, and a flow rate of 1.0 m ³ / min while rotating the substrate at the same rotational speed as in the induction heating step. The coating film of the layer was dried by far-infrared heating for 10 minutes to produce an electrophotographic photoreceptor of Example 4.

(Comparative Example 6)
An electrophotographic photosensitive member of Comparative Example 6 was produced in the same manner as in Example 4 except that the cylindrical conductive substrate was not rotated in the induction heating step and the far infrared heating drying step.

[Evaluation 2]
The film thickness distribution near the center in the axial direction of the charge transport layer in the circumferential direction of the electrophotographic photosensitive member produced in Example 4 and Comparative Example 6 was measured with a multifunctional multichannel spectrophotometer (MCPD2000, manufactured by Otsuka Electronics Co., Ltd.). did.

  FIG. 4 is a view showing the film thickness distribution in the circumferential direction of the electrophotographic photoreceptors produced in Example 4 and Comparative Example 6. Note that the circumferential position shown in FIG. 4 is a point to indicate the position when the reference point existing on the surface of the charge transport layer is in the vertical plane including the axis of the photosensitive member as a reference (0 degree). Is the angle at which the photoconductor rotates about the axis when it is placed at the position where the reference point exists in the vertical plane.

  As in Example 4, when the axial direction of the cylindrical conductive substrate is held parallel to the horizontal direction and dried while rotating around the axial line, the film thickness is substantially constant in the circumferential direction. A thickness distribution could be obtained. On the other hand, as in Comparative Example 6, the photosensitive body that was held in parallel with the axis direction of the conductive substrate but was not rotated around the axis line had a coating solution whose viscosity decreased and fluidity increased with an increase in temperature. Gravity caused the conductive substrate to hang down in the direction of gravity, resulting in uneven film thickness in the circumferential direction.

(Comparative Example 7)
An electrophotographic photoreceptor of Comparative Example 7 was produced in the same manner as in Example 4 except that the output of the induction heating apparatus was 500 W and the substrate temperature was increased to 171 ° C.

[Evaluation 3]
For the electrophotographic photoreceptors produced in Example 4 and Comparative Example 7, the amount of residual solvent was quantified in the same manner as in Evaluation 1. In addition, each photoconductor is mounted on a laser printer (DM-4501, manufactured by Sharp Corporation), and a surface potential meter (on the inside of the laser printer body so that the surface potential of the electrophotographic photoconductor in the image forming process can be measured. CATE751, manufactured by Gentec Co., Ltd.), in a high temperature and high humidity environment of 35 ° C./80% relative humidity, and in a low temperature and low humidity environment of 5 ° C./20%, a charging potential Vo (V) that is the surface potential immediately after charging. The exposure potential VL (V), which is the surface potential immediately after the exposure with the laser beam, was measured. Furthermore, this potential measurement was performed both at the initial stage before image formation and after fatigue after 10,000 image formation. The surface of the electrophotographic photosensitive member was charged by a negative charging process.

  Furthermore, a halftone image for image quality evaluation was formed at an initial stage and after fatigue after 10,000 images were formed, and image defects and image quality were evaluated. The obtained halftone image was visually observed, and the image quality was evaluated according to the degree of image defects such as white spots, black belts, and image blur. The evaluation criteria for image quality were as follows.

A: Good. No image defects.
B: Somewhat bad. There are image defects that can be ignored.
C: Defect. There is an obvious image defect.

  Table 3 shows the charging potential Vo and exposure potential VL measured under the conditions as described above, and the evaluation results of the formed image, together with the temperature of the conductive substrate immediately after the induction heating step and the amount of residual solvent in the charge transport layer. Shown in

  According to the results shown in Table 3, the electrophotographic photoreceptors produced in Example 4 and Comparative Example 7 were able to dry almost all the solvent in the photosensitive layer. However, the electrophotographic photosensitive member produced in Comparative Example 7 has a difference between the initial stage charging potential Vo and the post-fatigue charging potential Vo and the initial stage exposure in both high temperature and high humidity environments and low temperature and low humidity environments. The difference between the potential VL and the exposure potential VL after fatigue was larger than that of the electrophotographic photosensitive member produced in Example 4, and lacked repeated stability.

  In addition, the electrophotographic photosensitive member produced in Comparative Example 7 has a particularly large difference between the exposure potential VL in the high temperature and high humidity environment and the exposure potential VL in the low temperature and low humidity environment both in the initial stage and after fatigue. The environmental stability was bad. Furthermore, the image formed by the photoconductor produced in Comparative Example 7 had a clear image defect and could not be put to practical use.

  As described above, according to the method for producing a coating film-coated substrate of the present invention, it is possible to easily form a photosensitive layer composed of a smooth coating film that does not generate pinholes, bubbles, surface unevenness, etc. in a short time. I understand that I can do it. In addition, it was confirmed that the photoconductor produced by the method for producing a photoconductor of the present invention was excellent in repetitive stability and environmental stability and could form a good image.

It is a side view which simplifies and shows the structure of the drying apparatus 1 for implementing the induction heating process and the far-infrared heating drying process in the manufacturing method of the electrophotographic photosensitive member which is one Embodiment of this invention. It is a side view which shows roughly the structure of the drying apparatus 11 for implementing the induction heating process and the far-infrared heating drying process in the manufacturing method of the photoreceptor of this invention. It is a graph which shows the result of having measured the time-dependent change of the coating-film temperature in the induction heating process and far-infrared heat drying process of Examples 1, 2 and Comparative Examples 1-3. It is a figure which shows the film thickness distribution of the circumferential direction of the electrophotographic photoreceptor produced in Example 4 and Comparative Example 6. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Drying device 2,15a, 15b Electromagnetic induction heating means 3,16a, 16b Far-infrared heating means 4,17a, 17b Blast nozzle 5,12 Conductive base 6,13 Coating film 7 Rotating means 14a, 14b Base substrate

Claims (3)

In a method for producing a coating film-coated substrate having a coating film formed by applying a coating solution containing a coating film-forming material and a solvent on a metal substrate,
A coating process in which a coating liquid containing a coating film forming material and a solvent is coated on a substrate to form a coating film;
An induction heating step of heating the substrate on which the coating film is formed to 60 ° C. or more and 150 ° C. or less by an induction heating method;
A far-infrared heat drying step for drying the coating film formed on the substrate by heating with a far-infrared heating method,
When the ratio of the evaporation time of n-butyl acetate and the evaporation time of the solvent is the relative evaporation rate of the solvent,
The method for producing a coating film-coated substrate, wherein the solvent contains 30% by weight or more of a solvent having a relative evaporation rate of less than 1.7. The substrate is cylindrical or cylindrical,
The induction heating step and the far infrared heating drying step are:
2. The method for producing a coating-coated substrate according to claim 1, wherein the substrate is held while the axial direction is parallel to the horizontal direction and the substrate is rotated around the axial line. The metal substrate is a conductive substrate,
The coating film forming material is a photosensitive layer forming material,
3. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the coating film-coated substrate is an electrophotographic photosensitive member.

Images