JP2015221402A - Manufacturing method of rotor and manufacturing method of photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit dripping of a coating liquid caused in an upper part of a base substance by the self-weight of the coating liquid applied to the base substance in an immersing manner.SOLUTION: A manufacturing method of a rotor includes: a first step where a cylindrical or columnar base substance is moved down to be immersed in a coating liquid and downward movement of the base substance is stopped when an upper part of the base substance is exposed from the coating liquid; a second step where the base substance is held in a stop position of the first step for a predetermined time period; a third step where the base substance is further moved down after the second step; and a fourth step where the base substance is pulled up from the coating liquid after the third step.

Description

  The present invention relates to a method for manufacturing a rotating body and a method for manufacturing a photoreceptor.

  Patent Document 1 discloses a coating method in which a coating liquid (photosensitive layer) is applied to a substrate of a photosensitive drum. In this coating method, the substrate immersed in the coating tank is once pulled up and re-immersed so that the upper part of the coating area of the substrate is exposed to the air on the liquid surface for a predetermined time. Pull up from the coating tank.

JP 2002-82454 A

  It is an object of the present invention to suppress dripping that occurs at the top of a substrate due to the weight of the coating liquid dip-coated on the substrate.

  The first aspect of the present invention is a first step in which a cylindrical or columnar substrate is lowered and immersed in a coating liquid, and the lowering is stopped in a state where the upper portion of the substrate is exposed from the coating liquid; A second step of holding the substrate at a process stop position for a predetermined time, a third step of further lowering the substrate after the second step, and a coating of the substrate after the third step. A fourth step of lifting from the liquid.

  In the invention of claim 2, the substrate is lifted after being lowered without stopping halfway to the position lowered in the third step, and the dripping is caused by the weight of the coating liquid above the substrate. The generated range is measured in advance, and the first step stops the descent so that the liquid level of the coating liquid is located within the range.

  According to a third aspect of the present invention, a photosensitive layer is formed on the outer periphery of the substrate by the manufacturing method of the first or second aspect.

  According to the manufacturing method of claim 1 of the present invention, compared with the comparative example in which the substrate is pulled up without being stopped halfway to the position lowered in the third step and then the substrate is pulled up, the coating applied by dip coating on the substrate is performed. It is possible to suppress dripping that occurs at the top of the substrate due to the weight of the liquid.

  According to the manufacturing method of claim 2 of the present invention, the substrate was dip-coated on the substrate as compared with the comparative example in which the descent of the substrate was stopped so that the liquid level of the coating liquid was positioned outside the range of the manufacturing method. The dripping generated at the upper part of the substrate due to the weight of the coating liquid can be suppressed.

  According to the manufacturing method of claim 3 of the present invention, compared with the comparative example in which the substrate is pulled up without being stopped halfway to the position lowered in the third step, and then the substrate is pulled up, the axial end portion of the substrate is Thinning of the photosensitive layer can be suppressed.

It is the schematic which shows the structure of the dip coating apparatus which concerns on this embodiment. FIG. 2 is a schematic diagram illustrating a configuration of a photoconductor according to an exemplary embodiment. It is the schematic which shows the manufacturing method which concerns on this embodiment. It is the schematic which shows the manufacturing method which concerns on this embodiment. It is the schematic which shows operation | movement of the coating liquid with which the viscosity rose in the manufacturing method which concerns on this embodiment. It is the schematic which shows the dripping in the manufacturing method which concerns on this embodiment and a comparative example. It is a table | surface which shows the evaluation result of an Example and a comparative example.

  Below, an example of an embodiment concerning the present invention is described based on a drawing.

(Dip coater 10)
First, the dip coating apparatus 10 used for the manufacturing method mentioned later is demonstrated. FIG. 1 is a schematic view showing the configuration of a dip coating apparatus.

  As shown in FIG. 1, the dip coating apparatus 10 includes a coating liquid tank 12 in which a coating liquid L (coating liquid) into which the base 32 is immersed is stored, a storage unit 14 in which the coating liquid L is stored, and a storage. The supply pump 16 that supplies the coating liquid L of the section 14 to the coating liquid tank 12, the receiving section 18 that receives the coating liquid L overflowing from the upper part of the coating liquid tank 12, and the coating liquid L of the coating liquid tank 12. And an elevating device 20 that elevates and lowers the base body 32 so as to be immersed in the apparatus.

  In the dip coating apparatus 10, the coating liquid L is supplied from the storage unit 14 to the coating liquid tank 12 through the supply port 12 </ b> A at the lower part of the coating liquid tank 12 by the supply pump 16. Further, the receiving part 18 receives the coating liquid L overflowing from the opened upper part of the coating liquid tank 12, and the coating liquid L received by the receiving part 18 returns to the storage part 14. Thus, the coating liquid L circulates.

  Further, in the dip coating apparatus 10, the upper portion (axial end portion) of the substrate 32 is supported by the support portion 22 of the lifting device 20, and the substrate 32 is applied to the coating liquid L in the coating tank 12 by the lifting motion of the lifting device 20. The coating liquid L is applied to the outer periphery of the substrate 32 by being dipped in the coating liquid L and pulled up from the coating liquid L.

(Configuration of photoconductor and its constituent materials)
Next, a configuration of a photoconductor (an example of a rotating body) that is a manufacturing target of a manufacturing method that will be described later and its constituent materials will be described. FIG. 2 is a schematic view showing the structure of the photoreceptor.

  The photoreceptor 30 is a photoreceptor (photoreceptor drum) used in an electrophotographic image forming apparatus (laser printer or the like) that forms an image through processes such as charging, exposure, development, transfer, and fixing. Specifically, as shown in FIG. 2, the photoconductor 30 includes a cylindrical base 32 and a photosensitive layer 50. The photosensitive layer 50 includes an undercoat layer 34, a charge generation layer 36, a charge transport layer 38, and a surface layer 40 (overcoat layer). The undercoat layer 34, the charge generation layer 36, the charge transport layer 38, and the surface layer 40 are laminated on the outer peripheral surface of the base 32 in this order. Hereinafter, the constituent material of each part (each layer) will be described.

(Substrate 32)
As the base 32, for example, a conductive material is used. Specific examples of the substrate 32 include metal materials such as aluminum, copper, stainless steel, chromium, and nickel. “Conductive” means that the volume resistivity is less than 10 ¹³ Ωcm, for example.

(Underlayer 34)
The undercoat layer 34 is configured as a layer containing inorganic particles in a binder resin, for example. The undercoat layer 34 may contain a known additive.

  Examples of the inorganic particles include inorganic particles (conductive metal oxide) such as tin oxide, titanium oxide, zinc oxide, and zirconium oxide.

  Examples of the binder resin include acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, chloride Known polymer resin compounds such as vinyl-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, and charge transport property having a charge transporting group Examples thereof include conductive resins such as resins and polyaniline.

  The film thickness of the undercoat layer 34 is set to, for example, 15 μm or more and 50 μm or less.

(Charge generation layer 36)
The charge generation layer 36 is configured, for example, as a layer containing a charge generation material in a binder resin. The charge generation layer 36 may contain a known additive.

  Examples of the charge generation material include azo pigments such as bisazo and trisazo, condensed aromatic pigments such as dibromoanthanthrone, perylene pigments, pyrrolopyrrole pigments, phthalocyanine pigments, zinc oxide, and trigonal selenium.

  The binder resin may be selected from organic photoconductive polymers such as poly-N-vinyl carbazole, polyvinyl anthracene, polyvinyl pyrene and polysilane. Desirable binder resins include polyvinyl butyral resins, polyarylate resins (polycondensates of bisphenols and aromatic divalent carboxylic acids, etc.), polycarbonate resins, polyester resins, phenoxy resins, vinyl chloride-vinyl acetate copolymers, polyamides. Resins, acrylic resins, polyacrylamide resins, polyvinyl pyridine resins, cellulose resins, urethane resins, epoxy resins, caseins, polyvinyl alcohol resins, polyvinyl pyrrolidone resins, and the like.

  The film thickness of the charge generation layer 36 is set to, for example, 0.1 μm or more and 5.0 μm or less.

(Charge transport layer 38)
The charge transport layer 38 is configured as, for example, a layer containing a charge transport material in a binder resin. The charge transport layer 38 may contain a known additive.

  Examples of the charge transport material include known materials, such as oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, Phenyl-pyrazolin, pyrazoline derivatives such as 1- [pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, tris [4- (4,4- Diphenyl-1,3-butadienyl) phenyl] amine, N, N′-bis (3,4-dimethylphenyl) biphenyl-4-amine, tri (p-methylphenyl) aminyl-4-amine, dibenzylaniline, etc. Aromatic tertiary amino compounds, aromatic tertiary diaminos such as N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine Compound, 1,2,4-triazine derivatives such as 3- (4′-dimethylaminophenyl) -5,6-di- (4′-methoxyphenyl) -1,2,4-triazine, 4-diethylaminobenzaldehyde Hydrazone derivatives such as -1,1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) benzofuran, p- ( 2,2-diphenylvinyl) -N, N-diphenylaniline and other α-stilbene derivatives, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, hole transport materials such as poly-N-vinylcarbazole and its derivatives, chloranil , Quinone compounds such as bromoanthraquinone, tetracyanoquinodimethane compounds And electron transport materials such as fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone, xanthone compounds and thiophene compounds.

  Examples of the binder resin include polycarbonate resin (for example, polycarbonate resin such as bisphenol A or bisphenol Z type), acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, and acrylonitrile-styrene. Polymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride Resin, silicone resin, phenol-formaldehyde resin, polyacrylamide resin, polyamide resin, insulating resin such as chlorinated rubber, and polyvinylcarbazole, polyvinyl alcohol Anthracene, organic photoconductive polymers such as polyvinyl pyrene, and the like.

  The film thickness of the charge transport layer 38 is set to, for example, 5 μm or more and 50 μm or less.

(Surface layer 40)
The surface layer 40 includes, for example, a binder resin and fluorine-based particles. From the viewpoint of abrasion resistance, a curable resin is used as the binder resin, and from the viewpoint of improving toner transferability, fluorine-based particles are blended. The surface layer 40 may contain a known additive.

  Examples of the binder resin include a cross-linked product obtained by cross-linking a cross-linkable charge transport material.

  The material constituting the fluorine-based particles is not particularly limited as long as it is a resin containing a fluorine atom. For example, tetrafluoroethylene resin (PTFE), trifluorinated ethylene resin, hexafluoropropylene It is comprised from 1 type (s) or 2 or more types chosen from resin, a vinyl fluoride resin, a vinylidene fluoride resin, a 2 difluorinated ethylene chloride resin, and those copolymers.

(Photoconductor manufacturing method)
Next, a method for manufacturing a photoreceptor (an example of a rotating body) will be described. The method for producing a photoreceptor includes an undercoat layer forming step, a charge generation layer forming step, a charge transport layer forming step, and a surface layer forming step.

(Undercoat layer forming process)
In the undercoat layer forming step, the undercoat layer 34 is formed on the outer periphery of the substrate 32. Specifically, for example, a coating liquid obtained by adding the above-described constituent materials of the undercoat layer 34 to a solvent (dispersion medium) is applied to the base 32, and a coating film formed by the coating liquid is dried, whereby the base 32 is coated. An undercoat layer 34 is formed.

  As a method for applying the coating liquid to the substrate 32, known methods such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method are used. .

  Moreover, as a solvent (dispersion medium) for preparing the coating liquid, known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers, esters, etc. Selected. Specific examples of the solvent include methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, Organic solvents such as n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene are used. Moreover, you may use these solvents individually or in mixture of 2 or more types.

  In addition, as a method for dispersing the constituent material of the undercoat layer 34 in the liquid, for example, a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, an agitator, an ultrasonic disperser, a roll mill And a known dispersion method using a medialess disperser such as a high-pressure homogenizer.

(Charge generation layer forming process)
In the charge generation layer forming step, the charge generation layer 36 is formed on the surface of the undercoat layer 34 formed on the substrate 32. Specifically, for example, a coating liquid obtained by adding the above-described constituent materials of the charge generation layer 36 to a solvent (dispersion medium) is applied onto the surface of the undercoat layer 34 formed on the base 32, and the coating liquid is applied. The charge generation layer 36 is formed on the surface of the undercoat layer 34 by drying the coating film.

  As a method of applying the coating liquid onto the surface of the undercoat layer 34, a known application method is used as in the case of forming the undercoat layer 34. As the solvent (dispersion medium) for preparing the coating liquid, for example, a known organic solvent is used in the same manner as the coating liquid for forming the undercoat layer 34. As a method for dispersing the constituent material of the charge generation layer 36 in the liquid, a known dispersion method may be used as in the case of the coating liquid for forming the undercoat layer 34.

(Charge transport layer forming step)
In the charge transport layer forming step, the outer periphery of the substrate 32 on which the undercoat layer 34 (see FIG. 2) and the charge generation layer 36 (see FIG. 2) are formed by the dip coating method using the dip coating apparatus 10 shown in FIG. A coating liquid (coating liquid) obtained by adding the above-described constituent materials of the charge transport layer 38 (see FIG. 2) to a solvent (dispersion medium) is applied to form the charge transport layer 38.

  In addition, as a solvent (dispersion medium) for preparing the coating liquid, for example, a known organic solvent is used in the same manner as the coating liquid for forming the undercoat layer 34. As a method for dispersing the constituent material of the charge transport layer 38 in the liquid, a known dispersion method may be used as in the case of the coating liquid for forming the undercoat layer 34.

  Specifically, the charge transport layer forming process includes a stop process (an example of the first process), a holding process (an example of the second process), a descending process (an example of the third process), and a pulling process (an example of the fourth process). Example). At least in the holding step, the supply pump 16 of the dip coating apparatus 10 is stopped, and the supply of the coating liquid L from the storage unit 14 to the coating liquid tank 12 is stopped.

  In the stopping step, as shown in FIG. 3A, the base 32 on which the undercoat layer 34 and the charge generation layer 36 are formed is lowered and the base 32 is immersed in the coating liquid L. Specifically, the upper portion of the substrate 32 is supported by the support portion 22 of the dip coating apparatus 10, and the substrate 32 is placed in the coating liquid tank 12 containing the coating liquid L by the lifting device 20 (see FIG. 1). To lower. Then, as shown in FIG. 3B, the lowering of the base 32 is stopped in a state where the upper part of the base 32 is exposed from the coating liquid L.

  In the holding step, the substrate 32 is held for a predetermined specified time at the stop position (the position shown in FIG. 3B) in the stop step. At this time, the base | substrate 32 is immersed to the 1st immersion position (immersion part) shown by the dashed-two dotted line A in a figure.

  For example, the first immersion position is set as follows. That is, without stopping in the middle of the descent (without stopping at the stop position (the position shown in FIG. 3B)), the lowermost position (the position shown in FIG. 4A) described later in the descent process. In the case of the first comparative example in which the substrate 32 is pulled up after the substrate 32 is lowered (see FIG. 6A), a range in which dripping occurs due to the weight of the coating liquid L above the substrate 32 (in FIG. 6A). D range) is measured in advance, and the first immersion position is set within the range. That is, the descent of the base 32 is stopped in the stopping step so that the liquid surface (upper surface) of the coating liquid L is located within the range.

  The liquid dripping in the first comparative example occurs in a specific range from the upper end of the coating film by the coating liquid L, and the range in which the film thickness is thinner than the film thickness in the axial central portion of the substrate 32 is the liquid. It is the range where anyone has occurred. For example, an average value of measured values measured at four locations in the circumferential direction of the base body 32 every 90 ° by the eddy current film thickness measurement device is defined as a film thickness.

  The vertical length of the range (the range D in FIG. 6A) is, for example, 20 mm when the vertical length of the base body 32 is 300 to 350 mm. Since the degree of dripping varies depending on the viscosity of the coating liquid L, the vertical length of the range (the range of D in FIG. 6A) can vary depending on the viscosity of the coating liquid L.

  In the holding step, the substrate 32 is held for a specified time because the viscosity of the coating liquid L is evaporated by evaporation of the solvent on the liquid surface (gas-liquid interface) of the coating liquid L, and the liquid surface (gas-liquid interface) of the coating liquid L. The specified time is set in a range of 2 seconds to 20 seconds, for example.

  The lower limit of the specified time is set by the time required for the solvent of the coating liquid L to evaporate in the holding step and to increase to a viscosity necessary for exhibiting the required dripping suppression effect. This is because in the state where the viscosity of the coating liquid L has hardly increased, dripping occurs due to its own weight.

  On the other hand, the upper limit of the specified time is set so that when the substrate 32 is pulled up from the coating liquid L (lifting step), the viscosity is such that air bubbles can be discharged from the coating liquid L due to evaporation of the solvent. If the viscosity of the coating liquid L increases, the movement of the bubbles is restricted, and the coating liquid L does not flow easily and is thickened. If the viscosity of the coating liquid L is too high, the bubbles are discharged from the coating liquid L. Is inhibited.

  The degree of increase in viscosity per elapsed time varies depending on the boiling point (volatility) of the solvent of the coating liquid L, and thus the specified time can vary depending on the boiling point (volatility) of the solvent of the coating liquid L. In the coating liquid L using a known organic solvent, if it is in the range of 2 seconds or more and 20 seconds or less, the required dripping suppression effect is exhibited and the viscosity rises to ensure the discharge of bubbles.

  After the holding process, a descending process is performed. In the descending step, as shown in FIG. 4A, the substrate 32 is lowered until a part of the upper portion exposed in the holding step in the substrate 32 is immersed in the coating liquid L. Thereby, the base | substrate 32 is immersed to the 2nd immersion position shown by the dashed-two dotted line B in a figure. When the substrate 32 is immersed to the second immersion position, the substrate 32 is positioned at the lowest position (lowermost position) in the charge transport layer forming step.

  After the descending process, a pulling process is performed. In the pulling-up process, as shown in FIG. 4B, the substrate 32 immersed in the coating liquid L in the descending process is pulled up from the coating liquid L. Thereby, the coating liquid L is applied onto the charge generation layer 36.

  And the charge transport layer 38 is formed by wiping off the coating liquid L adhering to the lower end part of the base | substrate 32 pulled up from the coating liquid tank 12, and drying the coating film by the coating liquid L (removing a solvent by evaporation).

(Surface layer forming step)
In the surface layer forming step, the surface layer 40 is formed on the surface of the charge transport layer 38 formed on the substrate 32. Specifically, for example, a coating liquid obtained by adding the above-described constituent materials of the surface layer 40 to a solvent (dispersion medium) is applied onto the surface of the charge transport layer 38 formed on the base 32, and the coating liquid is used. The surface layer 40 is formed on the surface of the charge transport layer 38 by drying the coating film.

  As a method of applying the coating liquid onto the surface of the charge transport layer 38, a known coating method is used as in the case of forming the undercoat layer 34. As a solvent (dispersion medium) for preparing a coating liquid for forming the surface layer 40, for example, a known organic solvent is used in the same manner as the coating liquid for forming the undercoat layer 34. As a method for dispersing the constituent material of the surface layer 40 in the liquid, a known dispersion method may be used as in the case of the coating liquid for forming the undercoat layer 34.

  As described above, a photoreceptor (an example of a rotating body) used in an electrophotographic image forming apparatus through the above-described undercoat layer forming step, charge generation layer forming step, charge transport layer forming step, and surface layer forming step. Is manufactured.

(Operation according to this embodiment)
In the charge transport layer forming step in the manufacturing method of the present embodiment, as shown in FIG. 3B, the substrate 32 is lowered so as to be immersed up to the first immersion position of the substrate 32 (position of the two-dot chain line A). And the base 32 is held at the stop position for a predetermined time. As described above, the base 32 stays at the stop position (position shown in FIG. 3B) for a specified time, so that the flow of the coating liquid L (overflowing operation) is delayed, and as shown in FIG. In the liquid surface (gas-liquid interface) of the coating liquid L, the solvent of the coating liquid L evaporates and the viscosity of the coating liquid L increases. The coating liquid LA whose viscosity has increased around the substrate 32 adheres to the first immersion position (the position of the two-dot chain line A) of the substrate 32. In FIGS. 5A, 5B, and 5C, the coating liquid having an increased viscosity is indicated by reference sign LA.

  On the other hand, in the first comparative example in which the base 32 is pulled up without being stopped halfway to the lowest position (position shown in FIG. 4A) in the lowering step, the liquid level of the coating liquid L (gas Since the state in which the coating liquid L flows is maintained at the liquid interface), the viscosity of the coating liquid L does not increase locally. Therefore, adhesion of the coating liquid LA having an increased viscosity to the substrate 32 does not occur. For this reason, as shown in FIG. 6A, in the upper part of the substrate 32, dripping due to the gravity of the coating liquid L occurs in the range of the reference sign D.

  For this reason, the thickness of the charge transport layer formed is thinner at one axial end of the substrate 32 than at the central portion in the axial direction, and the thickness of the charge transport layer varies in the axial direction of the substrate 32. If the film thickness of the charge transport layer varies in the axial direction of the substrate 32, uneven charging occurs and uneven density of the image occurs, and the lifetime due to wear of the photosensitive layer depends on the portion where the thickness of the charge transport layer is thin. As a result, the life of the photoreceptor is shortened.

  Accordingly, a portion where the thickness of the charge transport layer is thin cannot be used as an image area, and the range R that can be used as an image area in the base 32 is narrowed. Therefore, in order to ensure the required image area, it is necessary to lengthen the base 32.

  In the second comparative example in which the base 32 is lowered without being stopped halfway to the lowest position in the lowering step (the position shown in FIG. 4A) and held for a predetermined time, and then the base 32 is pulled up. The coating liquid having an increased viscosity adheres to the second immersion position (position of the two-dot chain line B) of the substrate 32. For this reason, as shown in FIG. 6 (B), the coating liquid L is downward at the second immersion position (the position of the two-dot chain line B) of the base 32, that is, at the upper end of the coating liquid L applied to the base 32. And the dripping due to the gravity of the coating liquid L is suppressed. However, dripping due to the gravity of the coating liquid L occurs below the upper end of the substrate 32. Accordingly, as in the first comparative example, the range R that can be used as the image area is narrowed, and the base 32 needs to be lengthened to ensure the required image area.

  On the other hand, in this embodiment, as shown in FIG. 5A, the coating liquid LA having an increased viscosity adheres to and adheres to the first immersion position (the position of the two-dot chain line A) of the base 32. The coating liquid LA follows the ascending / descending operation of the base 32 in the lowering process (see FIG. 5B) and the lifting process (see FIG. 5C).

  When the base 32 is pulled up (lifting step), the coating liquids L and LA applied to the base 32 are less likely to flow downward at the first immersion position of the base 32 (the position of the two-dot chain line A). For this reason, as shown in FIG. 6C, dripping that occurs below the upper end of the coating liquid L applied to the base 32 at the top of the base 32 is suppressed.

  For this reason, the coating film by the coating liquid L is thickened on the upper portion of the substrate 32, and the above-mentioned problems such as uneven image density due to the variation in film thickness and the short life of the photosensitive member due to wear of the photosensitive layer are solved. The range R that can be used as an image area is enlarged. As a result, the axial length of the base 32 necessary to obtain an image area having a required length can be reduced, and the manufacturing cost of the photoreceptor can be reduced.

  Note that, since the viscosity of the coating liquid L is not increased above the first immersion position of the base 32, the liquid dripping occurs, but the coating liquid LA having an increased viscosity is at the first immersion position of the base 32. The coating liquid L whose viscosity has not increased is supported, and dripping of the coating liquid L is suppressed. In FIG. 6C, the dripping that occurs in the first comparative example (see FIG. 6A) is indicated by a two-dot chain line DA.

  In particular, in the present embodiment, in the holding step, in the case of the first comparative example, the coating liquid L falls within a range where the dripping occurs due to the weight of the coating liquid on the base 32 (range D in FIG. 6A). The descent of the base body 32 is stopped so that the liquid level is positioned. For this reason, a coating film is thickened in the range D which produces dripping in the 1st comparative example and the 2nd comparative example. For this reason, the area | region R which can be used as an image area is expanded more effectively.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Example 1]
-Formation of charge transport layer-
8 parts by mass of tetrafluoroethylene resin particles (average particle size: 0.2 μm) and 0.01 parts by mass of a fluorinated alkyl group-containing methacrylic copolymer (weight average molecular weight 30000), 4 parts by mass of tetrahydrofuran, and 1 part by mass of toluene The mixture was kept at a liquid temperature of 20 ° C. and stirred for 48 hours to obtain a tetrafluoroethylene resin particle suspension A.

  Next, 4 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine as a charge transport material, and bisphenol Z type 6 parts by mass of polycarbonate resin (viscosity average molecular weight: 40,000), 0.1 part by mass of 2,6-di-t-butyl-4-methylphenol as an antioxidant are mixed, 24 parts by mass of tetrahydrofuran and 11 of toluene. Mass parts were mixed and dissolved to obtain a mixed solution B.

  Dispersion after increasing the pressure to 500 kgf / cm 2 using a high pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a penetrating chamber having a fine flow path after adding the A liquid to the B liquid and stirring and mixing. 5 ppm of fluorine-modified silicone oil (trade name: FL-100 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the solution obtained by repeating the treatment six times, and the mixture was sufficiently stirred to obtain a coating solution for forming a charge transport layer.

  This coating solution was adjusted to a temperature of 24 ° C. and a viscosity of 440 mPa · s, and applied on an aluminum pipe substrate having an outer diameter of 30 mm and a length of 340 mm based on the above-described charge transport layer forming step. While descending the substrate, it was stopped for 5 seconds at a stop position 6 mm shallower than the lowest position, then dipped to the lowest position, and pulled up to a film thickness of 30.0 μm at the center at a pulling rate of 170 mm / min. Was dried to prepare the charge transport layer of Example 1.

[Example 2]
A charge transport layer was prepared under the same conditions except that the stop time described in Example 1 was 2 seconds.

[Example 3]
A charge transport layer was prepared under the same conditions except that the stop time described in Example 1 was 10 seconds.

[Example 4]
A charge transport layer was prepared under the same conditions except that the stop time described in Example 1 was 15 seconds.

[Example 5]
A charge transport layer was prepared under the same conditions except that the stop time described in Example 1 was 20 seconds.

[Example 6]
A coating solution was obtained under the same conditions except that 1,4-dioxane (boiling point was higher than tetrahydrofuran) was used as the coating solution described in Example 1 instead of tetrahydrofuran. Thereafter, a charge transport layer was prepared under the same conditions as described in Example 1.

[Example 7]
A coating solution was obtained under the same conditions except that 1,4-dioxane was used as the coating solution described in Example 1 instead of tetrahydrofuran. A charge transport layer was prepared under the same conditions except that the stop time described in Example 1 was 20 seconds.

[Comparative Example 1]
The substrate was lowered without stopping halfway to the lowest position described in Example 1, and then the substrate was pulled up to form a charge transport layer. Other conditions are the same as in the first embodiment.

(Evaluation)
The film thickness of the charge transport layer prepared in Examples 1 to 7 and Comparative Example 1 is 50 mm or more and 310 mm from the upper end (application start position on the upper end side) of the charge transport layer using an eddy current film thickness measurement device (manufactured by our company). Measurements were made at intervals of 20 mm at four locations in the circumferential direction every 90 °, and the average value was defined as the average film thickness A (μm).

  Measurement was performed at four locations in the circumferential direction every 90 ° at 10 mm from the upper end of the charge transport layer, and the average value was defined as the film thickness B (μm), and the value AB was defined as the amount of the upper part of the substrate.

  Further, it was visually confirmed whether or not the prepared charge transport layer had a coating film defect due to bubbles. In the evaluation results shown in FIG. 7, the case where there was no coating film failure was indicated as “◯”, and the case where bubbles were confirmed but did not affect the image quality was indicated as “Δ”.

  Further, the photoconductor drum having the charge transport layer prepared in Examples 1 to 6 and Comparative Example 1 was incorporated into an electrophotographic image forming apparatus, and image quality evaluation was performed. In the image quality evaluation, a single-color halftone image was output on a sheet, and the density unevenness on the halftone image was visually evaluated. In the evaluation results shown in FIG. 7, “◯” indicates that no density unevenness is found in the halftone image, and “Δ” indicates that there is no problem in image quality although there is a slight density unevenness in the halftone image. A case where density unevenness was found in the image and there was a problem with the image quality was indicated as “x”.

  As a result, as shown in FIG. 7, the upper liquid dripping amount was reduced in Examples 1 to 7 as compared with Comparative Example 1. In addition, the image quality density unevenness was also better in Examples 1-7 than in Comparative Example 1. In Example 5, although a coating film defect due to bubbles was confirmed, there was no effect on image quality density unevenness.

(Modification)
In the above-described descending step, the substrate is lowered until a part of the exposed upper portion of the substrate 32 is immersed in the coating liquid in the stopping step and the retaining step. The substrate may be lowered until the entire upper part exposed in step 1 is immersed in the coating solution.

  Further, the manufactured rotating body is not limited to the photosensitive body (photosensitive drum), and may be a roll-shaped member such as a fixing roll.

  Further, the shape of the substrate 32 immersed in the coating liquid L is not limited to a cylindrical shape, and may be formed in a columnar shape, for example.

  In the present embodiment, the charge transport layer 38 is formed by the dip coating method including the stop process, the holding process, the descending process, and the pulling process in the charge transport layer forming process, but the present invention is not limited to this. For example, when forming the undercoat layer 34, the charge generation layer 36, and the surface layer 40, a configuration in which dip coating is performed using the dip coating method may be employed.

  Further, in the above-described stopping step, in the case of the first comparative example (see FIG. 6A), within the range where dripping occurs due to the weight of the coating liquid L above the base 32 (D in FIG. 6A). Although the descent of the base body 32 is stopped so that the liquid level of the coating liquid L is located in the range), the present invention is not limited to this. For example, it may be stopped at the lower side of the range of D in FIG. 6A (slightly lower side of the range), and may be stopped with the upper portion of the base 32 exposed.

  The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made without departing from the spirit of the present invention. For example, the modification examples described above may be appropriately combined.

30 photoconductor (an example of a rotating body)
32 Substrate 50 Photosensitive layer L Coating liquid

Claims (3)

A first step in which a cylindrical or columnar substrate is lowered and immersed in a coating liquid, and the lowering is stopped in a state where the upper portion of the substrate is exposed from the coating liquid;
A second step of holding the substrate at a stop position of the first step for a predetermined time;
A third step of further lowering the substrate after the second step;
A fourth step of lifting the substrate from the coating liquid after the third step;
The manufacturing method of the rotary body which has this. Measuring the range in which dripping occurs due to the weight of the coating liquid at the upper part of the substrate by pulling up the substrate after lowering the substrate without stopping halfway to the position lowered in the third step,
The method of manufacturing a rotating body according to claim 1, wherein the first step stops the descent so that the liquid level of the coating liquid is located within the range.   A method for producing a photoreceptor, wherein a photosensitive layer is formed on the outer periphery of the substrate by the production method according to claim 1.