JP2015176084A - Method of manufacturing electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an electrophotographic photoreceptor, which efficiently removes aggregated particles to suppress image defects due to deposition of aggregated particles.SOLUTION: The method of manufacturing an electrophotographic photoreceptor uses a dip coating device and includes a step (i) of cleaning a coating bath or a recovery tank with a solvent satisfying formulae (1) and (2) before introduction of a coating liquid to a coating device and a step (ii) of introducing the coating liquid to the coating device and performing dip coating while circulating the coating liquid.

Description

  The present invention relates to a method for producing an electrophotographic photoreceptor.

  Electrophotographic photoreceptors are widely used in the market due to recent rapid spread of copying machines, laser beam printers and the like. As an electrophotographic photoreceptor, a photoreceptor having an undercoat layer for the purpose of charge blocking from a conductive substrate is generally used. Also disclosed is a technique for suppressing interference fringes in an output image by containing particles (organic resin particles) in an undercoat layer and scattering light of a semiconductor laser used as an exposure means. As the particles, hydrophobic organic resin particles such as silicone resin particles having an average primary particle size of 1.0 μm or more, and organic resin particles such as crosslinked polymethyl methacrylate resin (crosslinked PMMA) particles are used. Patent Document 1 discloses an electrophotographic photoreceptor in which an undercoat layer contains a metal oxide surface-treated with a specific amount of aminosilane and crosslinked polymethyl methacrylate resin particles.

  In these electrophotographic photoreceptor manufacturing methods, as a method of applying the coating liquid of each layer, a dip coating method, a spray coating method, a ring coating method, a spin coating method, a roller coating method, a Meyer bar coating method, a blade coating method, etc. The coating method is known. Of these, the dip coating method is advantageous in producing a cylindrical electrophotographic photosensitive member, and is generally widely used because it can be applied simultaneously to a plurality of electrophotographic photosensitive members. This method uses a coating tank containing a coating liquid and a device for holding and lifting the coated body, soaking the coated body in the coating tank, and then pulling it up at an appropriate speed, A coating film is formed on the surface. Usually, the dip coating apparatus has a coating tank and a recovery tank, and is used in a state where the coating liquid is circulated.

  When production is not performed for a certain period due to maintenance or production adjustment, or when another coating liquid having different components is used in the same coating apparatus, the coating liquid is temporarily recovered from the coating apparatus. At this time, it is necessary to clean the coating apparatus, but usually the solvent contained in the coating solution used is often used as the cleaning solvent. Further, in Patent Document 2, before supplying the coating liquid to the coating apparatus, the coating liquid or a solution containing the main components of the coating liquid is introduced into the coating apparatus, and is preliminarily removed after being circulated. A coating method is disclosed. It is described that this makes it possible to eliminate the non-uniformity of the composition of the coating liquid due to the residual solvent in the coating apparatus.

JP 2013-114177 A Japanese Patent Laid-Open No. 10-314659

  However, as a result of the study by the present inventors, it was found that when the particles having the average primary particle size of 1.0 μm or more are contained in the coating liquid, the particles may be aggregated inside the photoreceptor coating apparatus. It was. For example, during the period in which the electrophotographic photosensitive member is produced by dip coating in a state where the coating solution is circulated, aggregation is suppressed because a certain pressure is applied to the coating solution in the circulation direction. However, when the circulation of the coating apparatus is stopped, the specific gravity of the particles is high with respect to the solvent of the commonly used coating solution, and thus the organic resin particles tend to settle. The settled particles are aggregated with each other, and an aggregate in which the particles and other coating liquid components are mixed is easily formed inside the coating apparatus.

  When collecting the coating liquid in the coating apparatus, there is a coating liquid that is held in the dead space of the apparatus or piping and cannot be collected easily, and the above-mentioned aggregates tend to stagnate there. Usually, after the coating liquid in the coating apparatus is collected, circulation cleaning in the coating apparatus is often performed using a solvent for forming the coating liquid or a part thereof. However, although a part of the agglomerate that has settled down and is once separated is peeled and collected again, it is difficult to remove all of the agglomerate, and the remaining agglomerate becomes dry. When the electrophotographic photosensitive member is manufactured again using the same coating apparatus after a certain period of time, the aggregate inside the apparatus gradually peels off and circulates in the coating apparatus while aggregating, so that the electrophotographic photosensitive member is being produced. There is a possibility of sticking to. When the aggregates adhere to the coating film of the electrophotographic photosensitive member, the uniformity of the film thickness of the electrophotographic photosensitive member is lost, and it tends to cause image defects such as black spots in the output image.

As described above, the object of the present invention is to provide an electrophotographic photosensitive member by dip coating using a coating solution for an electrophotographic photosensitive member containing particles having an average primary particle size of 1.0 μm or more.
An object of the present invention is to provide a method for producing an electrophotographic photosensitive member that efficiently removes aggregated particles and suppresses image defects due to adhesion of the aggregated particles.

The present invention is a method for producing an electrophotographic photosensitive member having a coating tank and a collection tank for supplying a coating liquid to the coating tank, and using a coating apparatus that applies the coating liquid to a coated body by dip coating,
(I) a step of washing the coating tank or the recovery tank with a solvent satisfying the following formulas (1) and (2) before introducing the coating solution into the coating apparatus; and (ii) the coating solution. A step of performing dip coating in a state where the coating liquid is circulated,
The present invention relates to a method for producing an electrophotographic photosensitive member, characterized in that the coating liquid contains particles having an average primary particle size of 1.0 μm or more, which has a specific gravity greater than that of a binder resin and a solvent contained in the coating liquid.

| SP ₁ −SP ₂ | ≦ 1.0 (cal / cm ³ ) ^1/2 (1)
(In Formula (1), SP ₁ represents the SP value of the solvent, and SP ₂ represents the SP value of the binder resin.)
d ₁ / d ₂ ≧ 0.69 Formula (2)

  According to the present invention, in a method for producing an electrophotographic photosensitive member by dip coating using a coating solution for an electrophotographic photosensitive member containing particles having an average primary particle size of 1.0 μm or more, the aggregated particles are efficiently removed. It is possible to provide a method for producing an electrophotographic photosensitive member that suppresses image defects caused by adhesion of removed and aggregated particles.

It is a figure which shows an example of the coating device (dip coating device) of the electrophotographic photosensitive member which concerns on this invention.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

  The present invention uses a coating apparatus that has a coating tank and a recovery tank that supplies the coating liquid to the coating tank, and that applies the coating liquid to an object to be coated by dip coating. The present invention has the following two features. First, the method for producing an electrophotographic photosensitive member includes (i) a step of washing the coating tank or the recovery tank using a solvent satisfying the formulas (1) and (2) before introducing the coating liquid into the coating apparatus. , (Ii) introducing a coating solution into a coating device and performing dip coating in a state where the coating solution is circulated.

| SP ₁ −SP ₂ | ≦ 1.0 (cal / cm ³ ) ^1/2 (1)
(In Formula (1), SP ₁ represents the SP value of the solvent, and SP ₂ represents the SP value of the binder resin.)
d ₁ / d ₂ ≧ 0.69 Formula (2)
(In formula (2), d ₁ represents the specific gravity of the solvent, and d ₂ represents the specific gravity of the particles.)
The other is that the coating liquid contains particles having an average primary particle size of 1.0 μm or more, which has a specific gravity greater than that of the binder resin and the solvent contained in the coating liquid.

  Particles having an average primary particle size of 1.0 μm or more having a specific gravity greater than that of the solvent contained in the coating solution are mainly contained in the undercoat layer of the electrophotographic photoreceptor, and the surface roughness and transmittance of the undercoat layer are adjusted, or Used for the purpose of reducing cracks in the pulling layer. As the particles, hydrophobic organic resin particles such as silicone resin particles and hydrophilic organic resin particles such as crosslinked polymethyl methacrylate particles (PMMA) are used, and crosslinked PMMA particles are particularly preferable.

Furthermore, it is preferable that the solvent satisfies the following formula (3).
d ₁ / d ₂ ≧ 0.76 Formula (3)
(In formula (3), d ₁ represents the specific gravity of the solvent, and d ₂ represents the specific gravity of the particles.)

  An example of a coating apparatus according to the present invention is shown in FIG. In the coating apparatus shown in FIG. 1, the coating liquid is fed to the lower part of the coating tank 2 via the recovery tank 3 by liquid feeding means 4 such as a pump. The coating liquid that exceeds the coating liquid level 7 falls into the overflow tank 5 and is then circulated to the recovery tank 3 via the pipe. In addition, the cover lid 6 provided with a through-hole for allowing the substrate 1 to pass through covers the top of the coating tank 2 and suppresses the entry of foreign matter into the coating solution and the volatilization of the solvent from the coating solution. doing. Part of the cylindrical coated body 1 is gripped by lifting means (not shown), dipped in a coating solution in the coating tank 2 and then pulled up to form a wet paint film on the surface. Is done.

  The cleaning of the present invention mainly includes the same binder resin and particles after producing the photoconductor using the coating liquid in the coating apparatus, collecting the coating liquid, storing it without using the coating apparatus for a certain period of time. This is preferably performed when using a coating solution. Specifically, before storing the coating device, the coating solution and solvent in the coating device are collected, and before all the solvent is volatilized, circulating cleaning is performed with a solvent satisfying the above formulas (1) and (2). Is preferred. Furthermore, it is more preferable to carry out circulation cleaning with a solvent satisfying the above formulas (1) and (2) as a pre-stage at the next use even after storage of the coating apparatus.

The formula (1) means that the difference between the SP value of the cleaning solvent and the SP value of the binder resin in the coating solution is small. The SP value (solubility parameter) is a parameter defined on the assumption that the force acting between the solvent and the solute is an intermolecular force, and is defined by the square root of the cohesive energy density as shown in the following formula (4).
SP value = (ΔE / V) ^1/2 (4)
(In the formula (4), ΔE is the cohesive energy and V is the molar molecular volume.)
As a result of examination, it is known that two components having a small difference in SP value have high solubility.

  The main component of adhesion that may occur when collecting the coating liquid and storing the coating apparatus is particles having an average primary particle size of 1.0 μm or more. However, when the particles settle and aggregate in the coating device, the binder resin, and other particles and additives contained in the coating liquid, if necessary, are mixed with the solid components that make up the coating liquid. It is expected to agglomerate in this state. In order to peel this aggregate inside the coating apparatus, it is considered efficient to dissolve a binder resin that contains a certain amount in the aggregate component and is soluble in the solvent. Therefore, it is presumed that using a solvent having a small difference in SP value from the binder resin in the coating solution contributes to the effect of peeling off the aggregates inside the coating apparatus.

  As the solvent constituting the coating solution, a solvent that dissolves the binder resin is selected. However, the solvent of the coating solution is not only soluble in the binder resin, but also particle dispersibility, long-term stability of the dispersion, reactivity with other components, coating properties (boiling point, viscosity, etc.), It is necessary to select an appropriate one in consideration of the influence on the characteristics of the electrophotographic photoreceptor due to the residual of the toner.

  As a method for obtaining the SP value, various methods are known: a method of estimating from the physical property value and a method of estimating from the molecular structure. The SP value of a general solvent is described in the literature, and for example, “Plastic Processing Technology Handbook” (June 12, 1995, edited by Polymer Society, published by Nikkan Kogyo Shimbun) can be referred to.

Moreover, when there is no literature value, it can estimate from a molecular structure. In the present invention, Fedors' estimation method was used for solvents having no literature values and SP values of resins. The Fedors method is a calculation method that assumes that both the cohesive energy density and the molar molecular volume depend on the type and number of substituents, and the cohesive energy density obtained by adding the numerical values for each unit when the molecule is divided into units. Each uses a molar molecular volume.
SP value = (ΣEcoh / ΣV) ^1/2 formula (5)
(In formula (5), ΣEcoh represents the cohesive energy and ΣV represents the molar molecular volume.)

  Formula (2) means that the specific gravity of the cleaning solvent with respect to the specific gravity of the particles is a certain value or more. In order to efficiently discharge the aggregate separated from the coating apparatus from the coating apparatus in the cleaning process, it is necessary to prevent the aggregate from settling again. While the coating liquid or the cleaning liquid is circulated, settling is suppressed because a certain pressure is applied. However, after the circulation is completed, the liquid tends to settle during liquid recovery. These agglomerates are held in the dead space in the device and cause adhesion to cause image defects due to solidification by storage, so that the specific gravity of the solvent is larger than the particles in order to efficiently discharge from the coating device, When it is small, it is desirable that the dissociation is small.

  Next, the electrophotographic photoreceptor formed by the production method of the present invention will be described. The electrophotographic photoreceptor according to the present invention has a support, an undercoat layer formed on the support, and a photosensitive layer formed on the undercoat layer. The photosensitive layer functions as a single layer type photosensitive layer containing a charge generation layer material and a charge transport material in a single layer, a charge transport layer containing a charge transport material, and a charge generation layer containing a charge generation material. You may have any structure of the separated function separation type (lamination type) photosensitive layer. From the viewpoint of electrophotographic characteristics, a function separation type (lamination type) is preferable, and a function separation type (lamination type) in which a charge generation layer and a charge transport layer are sequentially laminated from the support side is more preferable. Further, if necessary, a protective layer may be further provided on the photosensitive layer.

  As the support (conductive support), for example, a support made of metal (made of alloy) such as cylindrical aluminum, aluminum alloy, stainless steel, nickel, or the like can be used. In addition, the metal support having a layer in which aluminum, an aluminum alloy, an indium oxide-tin oxide alloy, or the like is formed by vacuum deposition can also be used.

  Further, the surface of the support may be subjected to a cutting process, a roughening process, or an alumite process for the purpose of suppressing interference fringes due to scattering of laser light.

  An undercoat layer is provided between the support and the photosensitive layer (charge generation layer, charge transport layer). The undercoat layer is preferably formed by the production method of the present invention. When the undercoat layer is composed of two or more layers, it is preferable that at least one layer is formed by the production method of the present invention.

  In the undercoat layer coating solution, metal oxide particles are preferably used from the viewpoint of the stability of the output image. Examples of the metal oxide particles include titanium oxide, zinc oxide, tin oxide, zirconium oxide, and aluminum oxide. These metal oxides are preferably subjected to a surface treatment from the viewpoint of the dispersibility of the coating solution and the electrical characteristics of the electrophotographic photosensitive member. Among these, surface-treated zinc oxide is preferable. Further, two or more kinds of different metal oxide species, different surface treatments, or different specific surface areas may be used in combination.

  The undercoat layer coating solution preferably further contains an organic compound that interacts with the metal oxide particles. By containing the organic compound in the undercoat layer together with the metal oxide particles, it is possible to output an image with stable electrical characteristics and few image defects. Preferred organic compounds include benzophenone compounds having a hydroxy group and anthraquinone compounds having a hydroxy group.

  Examples of the binder resin for the undercoat layer include acrylic resin, allyl resin, alkyd resin, ethyl cellulose resin, ethylene-acrylic acid copolymer, epoxy resin, casein resin, silicone resin, gelatin resin, phenol resin, butyral resin, poly Acrylate resin, polyacetal resin, polyamideimide resin, polyamide resin, polyallyl ether resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl alcohol resin, polybutadiene resin, polypropylene resin, etc. Can be mentioned. Moreover, 1 type or 2 or more types can be mixed and used. Among these, a curable polyurethane produced by a crosslinking reaction between a hydroxy group-containing resin and an isocyanate compound is preferable.

For the purpose of adjusting the surface roughness of the undercoat layer, when particles having an average primary particle size of 1.0 μm or more are contained in the undercoat layer, the surface roughness Rz of the surface of the undercoat layer is 0.6 μm or more. It is preferably in the range of 0 μm or less, and RSm is preferably 0.010 mm or more and 0.024 mm or less. Here, Rz (μm) means 5 points from the highest peak and 5 points from the lowest valley bottom for each reference length of the roughness curve obtained by measuring the surface roughness of the undercoat layer surface. The average height (ten-point average roughness) when selected. Moreover, RSm (mm) represents the average value of the interval between the peaks and valleys (average interval of the irregularities) obtained from the intersection where the roughness curve obtained by the surface roughness measurement intersects the average line. Rz and RSm are measurement methods defined by JIS B0601: 2001 (ISO 4287: 1997).
Moreover, you may make a coating liquid for undercoat layers contain a leveling agent as needed.

The coating method for the undercoat layer is preferably a dip coating method according to the production method of the present invention.
The thickness of the undercoat layer is preferably about 0.5 to 30 μm, and more preferably 1 to 25 μm.

  Examples of the charge generation material include azo pigments such as monoazo, disazo, and trisazo, phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, indigo pigments such as indigo and thioindigo, perylene pigments such as perylene acid anhydride and perylene imide, Polycyclic quinone pigments such as anthraquinone, pyrenequinone, dibenzpyrenequinone, squarylium dyes, pyrylium salts and thiapyrylium salts, triphenylmethane dyes, quinacridone pigments, azurenium salt pigments, cyanine pigments such as quinocyanine, anthanthrone pigments, pyranthrone pigments, xanthenes Examples thereof include dyes, quinoneimine dyes, and styryl dyes.

Among these, phthalocyanine pigments and azo pigments are preferable from the viewpoint of sensitivity, and phthalocyanine pigments are more preferable. Among phthalocyanine pigments, oxytitanium phthalocyanine, chlorogallium phthalocyanine, or hydroxygallium phthalocyanine exhibits excellent charge generation efficiency.
These charge generation materials may be used alone or in combination of two or more.

  When the photosensitive layer is a laminated type, examples of the binder resin for forming the charge generation layer include acrylic resins, allyl resins, alkyd resins, epoxy resins, diallyl phthalate resins, styrene-butadiene copolymers, butyral resins, and benzal. Resin, polyacrylate, polyacetal, polyamideimide, polyamide, polyallyl ether, polyarylate, polyimide, polyurethane, polyester, polyethylene, polycarbonate, polystyrene, polysulfone, polyvinyl acetal, polybutadiene, polypropylene, methacrylic resin, urea resin, vinyl chloride-acetic acid Examples include vinyl copolymers, vinyl acetate resins, and vinyl chloride resins. Among these, a butyral resin is preferable. These may be used alone or in combination as a mixture or copolymer.

  The charge generation layer can be formed by applying a charge generation layer coating solution obtained by dispersing a charge generation material together with a binder resin and a solvent and drying the coating solution. Examples of the dispersion method include a method using a homogenizer, an ultrasonic disperser, a paint shaker, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, and a liquid collision type high-speed disperser. The ratio of the charge generation material and the binder resin is preferably in the range of 0.3: 1 to 10: 1 by mass ratio.

  Examples of the organic solvent used in the charge generation layer coating solution include alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogenated hydrocarbons, and aromatic compounds.

  The thickness of the charge generation layer is preferably 5 μm or less, and more preferably 0.1 μm or more and 2 μm or less. In addition, various sensitizers, antioxidants, ultraviolet absorbers, and plasticizers can be added to the charge generation layer as necessary.

  Examples of the charge transport material include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, and butadiene compounds. Among these, a triarylamine compound is preferable from the viewpoint of high charge mobility.

  When the photosensitive layer is a laminated type, examples of the binder resin used for the charge transport layer include acrylic resin, acrylonitrile resin, allyl resin, alkyd resin, epoxy resin, silicone resin, phenol resin, phenoxy resin, polyacrylamide, Examples include polyamideimide, polyamide, polyallyl ether, polyarylate, polyimide, polyurethane, polyester, polyethylene, polycarbonate, polysulfone, polyphenylene oxide, polybutadiene, polypropylene, and methacrylic resin. In particular, polyarylate and polycarbonate are preferable. These may be used alone or in combination as a mixture or copolymer.

  The charge transport layer can be formed by applying a charge transport layer coating solution obtained by dissolving a charge transport material and a binder resin in a solvent and drying it. The ratio of the charge transport material and the binder resin is preferably in the range of 0.3: 1 to 10: 1 by mass ratio. From the viewpoint of suppressing cracks, the drying temperature is preferably 60 ° C. or higher and 150 ° C. or lower, and more preferably 80 ° C. or higher and 120 ° C. or lower. The drying time is preferably 10 minutes or more and 60 minutes or less.

  Examples of the solvent used in the charge transport layer coating solution include alcohols such as propanol and butanol (particularly alcohols having 3 or more carbon atoms), aromatic hydrocarbons such as anisole, toluene, xylene, and chlorobenzene, methylcyclohexane, and ethyl. And cyclohexane.

  Further, when the charge transport layer has a laminated structure, the charge transport layer on the surface side of the electrophotographic photosensitive member is preferably formed as follows. That is, in order to increase the mechanical strength of the electrophotographic photosensitive member, it is preferable to form a layer obtained by curing a charge transport material having a chain polymerizable functional group by polymerization and / or crosslinking. Examples of the chain polymerizable functional group include an acryloyloxy group, a methacryloyloxy group, an alkoxysilyl group, and an epoxy group. In order to polymerize and / or crosslink a charge transport material having a chain polymerizable functional group, heat, light, radiation (electron beam or the like) can be used.

  When the charge transport layer of the electrophotographic photoreceptor is one layer, the thickness of the charge transport layer is preferably 5 μm or more and 40 μm or less, and more preferably 8 μm or more and 30 μm or less.

  The thickness of the charge transport layer on the support side of the electrophotographic photosensitive member when the charge transport layer has a laminated structure is preferably 5 μm or more and 30 μm or less. For the charge transport layer on the surface side of the electrophotographic photosensitive member, It is preferable that they are 1 micrometer or more and 10 micrometers or less.

  In addition, an antioxidant, an ultraviolet absorber, a plasticizer, and the like can be added to the charge transport layer as necessary.

  A protective layer for the purpose of protecting the photosensitive layer may be provided on the photosensitive layer. The protective layer can be formed by applying a protective layer coating solution obtained by dissolving the various binder resins described above in a solvent and drying the coating solution. Moreover, you may form a protective layer by apply | coating the coating liquid for protective layers obtained by dissolving a resin monomer or an oligomer in a solvent, and hardening and / or drying this. For curing, light, heat, or radiation (such as an electron beam) can be used.

  The thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, and particularly preferably 1 μm or more and 7 μm or less. Moreover, electroconductive particle etc. can also be added to a protective layer as needed.

  Further, the outermost layer of the electrophotographic photoreceptor may contain a lubricant such as silicone oil, wax, polytetrafluoroethylene particles, silica particles, alumina particles, and boron nitride.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these. In the examples, “part” means “part by mass”.
(Preparation of coating solution A for undercoat layer)
Undercoat layer coating solution A was prepared as follows.

100 parts of zinc oxide particles (specific surface area: 19 m ² / g, powder resistance: 4.7 × 10 ⁶ Ω · cm) are stirred and mixed with 500 parts of toluene, and 0.8 part of a silane coupling agent is added thereto. And stirred for 6 hours. Thereafter, toluene was distilled off under reduced pressure, followed by heating and drying at 140 ° C. for 6 hours to obtain surface-treated zinc oxide particles. As a silane coupling agent, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane (trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.)) was used.

  Next, 15 parts of a butyral resin having a molecular unit of about 40,000 having a structural unit represented by the following formula (5) as a polyol resin and 15 parts of a blocked isocyanate (trade name: Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.) are added to methyl ethyl ketone 68. And a mixed solution of 72 parts of 1-butanol. To this solution, 4.05 parts of a purified 2,3,4-trihydroxybenzophenone solution (solid content 10%) and 81 parts of surface-treated zinc oxide particles were added. This was dispersed in a sand mill apparatus using glass beads having a diameter of 0.8 mm in an atmosphere of 23 ± 3 ° C. for 3 hours. After dispersion, 0.01 parts of silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Silicone), crosslinked PMMA particles (trade name: TECHPOLYMER SSX-103, manufactured by Sekisui Plastics Co., Ltd., average primary particle size) 11 μm) was added and stirred to prepare an undercoat layer coating solution A.

  In addition, SP value of the butyral resin which has a structural unit shown by Formula (5) was calculated with 11.3. The cross-linked PMMA particles have a specific gravity of 1.20.

(In formula (5), the average values when a + b + c = 100 are a = 65, b = 1, and c = 34.)

(Preparation of coating liquid B for undercoat layer)
In the preparation of the coating solution A for the undercoat layer, a butyral resin having a structural unit represented by the structural formula (5) having a molecular weight of about 40,000 was converted into a molecular weight having a structural unit represented by the following structural formula (6) of about 53, 000 butyral resin. Otherwise, undercoat layer coating solution B was prepared in the same manner.

  In addition, SP value of the butyral resin shown by Structural formula (6) was calculated with 10.7.

(In the formula (6), the average values when a + b + c = 100 are a = 73, b = 5, and c = 22.

(Preparation of coating liquid C for undercoat layer)
In the preparation of the coating liquid A for the undercoat layer, silicone resin particles (trade name: Tospearl 120, manufactured by Momentive Performance Materials, average primary particle size 2.0 μm) were used instead of the crosslinked PMMA particles. Otherwise, undercoat layer coating solution C was prepared in the same manner. The specific gravity of the silicone resin particles is 1.32.

Example 1
The dip coating apparatus having the configuration shown in FIG. 1 is filled with the coating liquid A for the undercoat layer. After recovering the coating solution A for the undercoat layer from the coating device, a mixed solvent in which equal parts by mass of methyl ethyl ketone and 1-butanol are mixed is introduced from the recovery tank of the coating device, and this mixed solution is put into the entire coating device including the coating tank. After filling and circulating for 30 minutes, the mixed solution was recovered. Next, 1-methoxy-2-propanol (SP value 11.3 (calculated value), specific gravity 0.92) was similarly charged from the recovery tank, filled in the coating tank and the coating apparatus, and circulated for 30 minutes. It was later recovered. The cleaned coating device was stored for 1 month without any liquid. Before the coating apparatus was again used for forming the undercoat layer, circulation cleaning using 1-methoxy-2-propanol was similarly performed. Subsequently, circulation cleaning was performed with a mixed solvent of methyl ethyl ketone and 1-butanol, and after recovering the solvent, the undercoat layer coating solution A was charged into the coating apparatus.

(Manufacture of electrophotographic photoreceptor 1)
By using a coating apparatus filled with the coating solution A for the undercoat layer, the coating solution A for the undercoat layer is dip-coated on an aluminum cylinder having a diameter of 30 mm and a length of 370 mm, and this is dried at 160 ° C. for 40 minutes. An undercoat layer having a thickness of 18 μm was formed.

  Next, a crystalline hydroxygallium phthalocyanine crystal (charge generation material) having strong peaks at 7.4 ° and 28.1 ° with a Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction was prepared. 4 parts of this hydroxygallium phthalocyanine crystal and 0.04 part of a compound represented by the following structural formula (A)

Was added to a solution obtained by dissolving 2 parts of polyvinyl butyral (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. Thereafter, dispersion treatment was performed in a sand mill using glass beads having a diameter of 1 mm in an atmosphere of 23 ± 3 ° C. for 1 hour, and after dispersion treatment, 100 parts of ethyl acetate was added to prepare a charge generation layer coating solution. This charge generation layer coating solution was dip-coated on the undercoat layer, and the resulting coating film was dried at 90 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.19 μm.

  Next, 60 parts of a compound represented by the following formula (B) (charge transporting substance), 30 parts of a compound represented by the following formula (C) (charge transporting substance), 10 parts of a compound represented by the following formula (D), polycarbonate 100 parts of resin (trade name: Iupilon Z400, Mitsubishi Engineering Plastics Co., Ltd., bisphenol Z type polycarbonate), polycarbonate having a structural unit represented by the following formula (E) (viscosity average molecular weight Mv: 20000) 0.02 A coating solution for charge transport layer was prepared by dissolving a part in a mixed solvent of 600 parts of chlorobenzene and 200 parts of dimethoxymethane. The charge transport layer coating solution was dip coated on the charge generation layer to form a coating film, and the resulting coating film was dried at 100 ° C. for 30 minutes to form a charge transport layer having a thickness of 21 μm. .

  Next, a protective layer coating solution (second charge transport layer) was applied on the charge transport layer according to the following procedure.

  1.5 parts of fluorine atom-containing resin (trade name: GF-300, manufactured by Toagosei Co., Ltd.) was added to 1,1,2,2,3,3,4-heptafluorocyclopentane (trade name: Zeolora H , Manufactured by Nippon Zeon Co., Ltd.) and 45 parts of 1-propanol. Thereafter, a solution obtained by adding 30 parts of tetrafluoroethylene resin powder (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) was added to a high-pressure disperser (trade name: Microfluidizer M-110EH, US Microfluidics ( The dispersion liquid was obtained. Thereafter, 70 parts of a hole transporting compound represented by the following formula (F),

  30 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane and 30 parts of 1-propanol were added to the dispersion, and a polyflon filter (trade name: PF-040, manufactured by Advantech Toyo Co., Ltd.) ) To prepare a protective layer coating solution.

  This protective layer coating solution was dip-coated on the charge transport layer, and the resulting coating film was dried at 50 ° C. for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under the conditions of an acceleration voltage of 60 KV and an absorbed dose of 8000 Gy in a nitrogen atmosphere. Thereafter, heat treatment was performed for 1 minute in a nitrogen atmosphere under conditions where the temperature of the coating film was 130 ° C. The oxygen concentration from the electron beam irradiation to the heat treatment for 1 minute was 20 ppm. Next, heat treatment was performed in the atmosphere for 1 hour under the condition that the coating film became 110 ° C. to form a protective layer having a thickness of 5 μm. Thus, an electrophotographic photoreceptor 1 having an undercoat layer, a charge generation layer, a charge transport layer, and a protective layer on a conductive support was produced.

(Example 2)
In the same manner as in Example 1 except that benzyl alcohol (SP value 11.6 (calculated value), specific gravity 1.05) was used instead of 1-methoxy-2-propanol in Example 1, electrophotographic photosensitive Body 2 was produced.

(Example 3)
In the same manner as in Example 1 except that N, N-dimethylformamide (SP value 12.0, specific gravity 0.94) was used instead of 1-methoxy-2-propanol in Example 1, Body 3 was produced.

Example 4
In Example 1, an electrophotographic photoreceptor 4 was produced in the same manner as in Example 1 except that the undercoat layer coating solution B was used instead of the undercoat layer coating solution A.

(Example 5)
In Example 4, instead of 1-methoxy-2-propanol, except that ethylene glycol monoethyl ether (cellosolve) (SP value 9.9, specific gravity 0.93) was used, it was the same as Example 4 An electrophotographic photoreceptor 5 was manufactured.

(Example 6)
The coating device is filled with the coating liquid A for the undercoat layer. After recovering the coating liquid A for the undercoat layer from the coating apparatus, a mixed solvent in which equal parts by mass of methyl ethyl ketone and 1-butanol are mixed is introduced from the recovery tank of the coating apparatus, filled in the coating tank and the coating apparatus, and for 30 minutes. After being circulated, it was collected. Next, benzyl alcohol (SP value 11.6 (calculated value), specific gravity 1.05) was similarly charged from the collection tank, filled in the coating tank and the coating apparatus, circulated for 30 minutes, and then collected. The cleaned coating device was stored for 1 month without any liquid. Before the coating apparatus was used again for forming the undercoat layer, circulation cleaning using benzyl alcohol was similarly performed. Subsequently, circulation cleaning was performed with the mixed solvent of methyl ethyl ketone and 1-butanol, and after recovering the solvent, the undercoat layer coating solution C was charged into the coating apparatus.

  An electrophotographic photosensitive member 6 was produced in the same manner as in Example 1 by using a coating apparatus filled with the undercoat layer coating solution C.

(Example 7)
In Example 1, an electrophotographic photoreceptor 7 was produced in the same manner as in Example 1 except that the undercoat layer coating solution C was used instead of the undercoat layer coating solution A.

(Comparative Example 1)
In Example 1, electrophotographic photosensitive member C1 was produced in the same manner as in Example 1 except that methyl ethyl ketone (SP value 9.3, specific gravity 0.81) was used instead of 1-methoxy-2-propanol. did.

(Comparative Example 2)
Example 1 except that in Example 1, a mixed solvent (SP value 10.2, specific gravity 0.81) in which equal parts by mass of methyl ethyl ketone and 1-butanol were mixed instead of 1-methoxy-2-propanol was used. In the same manner as above, an electrophotographic photoreceptor C2 was produced.

(Comparative Example 3)
In Example 1, electrophotographic photoreceptor C3 was prepared in the same manner as in Example 1 except that 1-butanol (SP value 11.1 and specific gravity 0.81) was used instead of 1-methoxy-2-propanol. Manufactured.

(Comparative Example 4)
In Example 7, an electrophotographic photoreceptor C4 was produced in the same manner as in Example 7, except that methyl ethyl ketone was used instead of 1-methoxy-2-propanol.

(Comparative Example 5)
In Example 1, electrophotographic photosensitive member C5 was produced in the same manner as in Example 1 except that ethanol (SP value 14.8, specific gravity 0.79) was used instead of 1-methoxy-2-propanol. did.

<Sensitivity evaluation of electrophotographic photoreceptor>
As an electrophotographic apparatus for evaluation, a modified machine of a copy machine imageRUNNER iR-ADV C5051 manufactured by Canon Inc. was used. After leaving the electrophotographic photosensitive members 1 to 7 and C1 to C5 together with the copying machine in an environment of a temperature of 23 ° C. and a humidity of 50% RH for 3 days, the electrophotographic photosensitive member 1 is set in the copying machine and an A4 size halftone image is displayed. Output and image evaluation.

Halftone image evaluation is
If the black spot is not observed with the naked eye on the image,
A black spot with a width of 0.2 mm or less observed in a part of the image is “black spot level 2”.
A black spot with a width of 0.3 mm or less observed in a part of the image is “black spot level 3”.
A black spot with a width of 0.4 mm or more observed in a part of the image is “black spot level 4”.
It was.

  Further, the image evaluation was performed in the same manner for the electrophotographic photoreceptors 2 to 7 and C1 to C5. For the case where black spots were observed in the image, the surface of the photoreceptor was observed with the naked eye. The evaluation results are shown in Table 1.

  As shown in Table 1, according to the manufacturing method of the present invention, when the coating apparatus is cleaned using a specific cleaning solvent between the time when the coating liquid is recovered from the coating apparatus and before the next application, Compared to the case where no cleaning solvent is used, black spots on the image are suppressed.

Further, when the surface of the photoreceptor on which black spots were confirmed on the image was observed with the naked eye, aggregates were observed in accordance with the positions where the black spots were generated in the image evaluation.

Claims (6)

An electrophotographic photosensitive member manufacturing method using a coating tank and a recovery tank for supplying a coating liquid to the coating tank, and using a coating apparatus that applies the coating liquid to a coated body by dip coating,
(I) a step of washing the coating tank or the recovery tank with a solvent satisfying the following formulas (1) and (2) before introducing the coating solution into the coating apparatus; and (ii) the coating solution. A step of performing dip coating in a state where the coating liquid is circulated,
The method for producing an electrophotographic photoreceptor, wherein the coating solution contains particles having an average primary particle size of 1.0 μm or more, which has a specific gravity greater than that of the binder resin and the solvent contained in the coating solution.
| SP ₁ −SP ₂ | ≦ 1.0 (cal / cm ³ ) ^1/2 (1)
(In Formula (1), SP ₁ represents the SP value of the solvent, and SP ₂ represents the SP value of the binder resin.)
d ₁ / d ₂ ≧ 0.69 Formula (2)
(In formula (2), d ₁ represents the specific gravity of the solvent, and d ₂ represents the specific gravity of the particles.)   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the particles are organic resin particles.   The method for producing an electrophotographic photosensitive member according to claim 2, wherein the organic resin particles are crosslinked polymethyl methacrylate particles. The method for producing an electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the solvent satisfies the following formula (3).
d ₁ / d ₂ ≧ 0.76 Formula (3)
(In formula (3), d ₁ represents the specific gravity of the solvent, and d ₂ represents the specific gravity of the particles.)   The method for producing an electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the solvent is 1-methoxy-2-propanol, benzyl alcohol, N, N-dimethylformamide, or ethylene glycol monoethyl ether. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the binder resin is a polyurethane resin.

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