JP2010066673A - Method for manufacturing multilayer electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a multilayer electrophotographic photoreceptor in which the occurrence of a photomemory phenomenon is suppressed. <P>SOLUTION: The method includes: a step of preparing a coating liquid of a charge transport layer by dissolving a charge transport material and a binder resin in a solvent containing monochlorobenzene; a step of dip-coating an electrically conductive support body having a charge generating layer in the coating liquid of a charge transport layer; and a step of heating and drying the electrically conductive support while the solvent content of the applied coating liquid of the charge transport layer is equal to or more than 10% of the content when the application is completed. The photoreceptor contains a charge transport material having solubility of 50 mg/g or more and 300 mg/g or less in the solvent at 25°C, by 10 mass% or more and 100 mass% or less based on the entire charge transport material present in the charge transport layer, and contains a polycarbonate resin by 95 mass% or more and 99.9 mass% or less and a polyarylate resin by 0.1 mass% or more and 5 mass% or less based on the entire binder resin present in the charge transport layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  As an electrophotographic photosensitive member, a photosensitive layer (organic photosensitive layer) using an organic material as a photoconductive substance (a charge generating material or a charge transporting material) is provided on a support for the advantages of low cost and high productivity. An electrophotographic photosensitive member, so-called organic electrophotographic photosensitive member, is widely used. Organic electrophotographic photoreceptors have a charge generation layer containing a charge generating material such as a photoconductive dye or a photoconductive pigment, and a charge containing a charge transport material such as a photoconductive polymer or a photoconductive low molecular weight compound. The mainstream is a photosensitive layer formed by laminating a transport layer, that is, a so-called laminated photosensitive layer. This takes into account the advantages of high sensitivity and material design diversity.

  When using a photoconductive low molecular weight compound as the charge transport material, the charge transport layer can be formed by depositing the charge transport material itself by vacuum evaporation or the like, or dissolving the charge transport material in a solvent together with the binder resin. Alternatively, a method of coating by dispersing and forming a film can be mentioned. From the viewpoint of productivity, it is preferable to use the film formation method by coating described in the latter.

  When forming a film by coating, the selection of the binder resin is extremely important. The selection of the binder resin includes compatibility with the charge transport material, light transmission, gas permeability (shielding) such as oxygen and water vapor, charging characteristics, electrical resistance, solubility in the solvent used for coating, It is necessary to select in consideration of various properties such as solvent resistance against other solvents. In addition, when the charge transport layer is the outermost surface layer of the electrophotographic photosensitive member, a property to withstand mechanical external forces such as charging characteristics and wear is also strongly required.

  Here, an example of a binder resin generally used for the charge transport layer is shown.

  For example, acrylic resin, styrene resin, polyester resin, polycarbonate resin, polyarylate resin, polysulfone resin, polyphenylene oxide resin, epoxy resin, polyurethane resin, alkyd resin, and polymethyl methacrylate resin. Further, polystyrene resin, styrene-acrylonitrile copolymer resin, polycarbonate resin, polyarylate resin, diallyl phthalate resin or unsaturated resin may be used. These resins can be used alone, as a mixture or as a copolymer, or one or more of them can be used.

  Among the binder resins listed above, the polycarbonate resin is excellent in abrasion resistance, charging characteristics and solubility in organic solvents, and is useful as a binder resin for a charge transport layer of an electrophotographic photoreceptor (patent) Literature 1, Patent Literature 2).

  As described above, the electrophotographic photoreceptor contains a charge generating material such as a photoconductive dye or a photoconductive pigment, and a charge transport material such as a photoconductive polymer or a photoconductive low molecular weight compound. Yes. For this reason, when light strikes the photosensitive layer, charge carriers are generated by the charge generating material, and when an electric field is applied to the photosensitive layer, the movement of the charge carriers occurs due to the presence of the electric field and the charge transport material. In order to efficiently perform an electrophotographic process such as charging, exposure, development of toner, and transfer to a photoreceptor, the electrophotographic photoreceptor is required to have high sensitivity to exposure light and high charge carrier transport performance.

  However, at the same time, the electrophotographic photosensitive member is also required to have light resistance to light that should not be irradiated to the electrophotographic photosensitive member (hereinafter referred to as unnecessary light). Examples of unnecessary light include light that can be applied to the electrophotographic photosensitive member when the electrophotographic photosensitive member itself or the process cartridge having the electrophotographic photosensitive member is attached to or detached from the electrophotographic apparatus, such as room light or natural light. It is done. When unnecessary light is irradiated onto the electrophotographic photosensitive member, the sensitivity of the portion irradiated with unnecessary light may change substantially. When image output is performed in a state where the sensitivity change remains, unevenness in density may occur on the image due to a sensitivity difference between a portion irradiated with unnecessary light and a portion not irradiated with unnecessary light. This is a so-called photo memory or optical memory phenomenon.

  Many proposals have been made to prevent photo memory.

  For example, in the case of a process cartridge having an electrophotographic photosensitive member, a method of attaching a shutter to the process cartridge is disclosed for the purpose of preventing unnecessary light irradiation to the electrophotographic photosensitive member that occurs when the process cartridge is attached to and detached from the electrophotographic apparatus. (Patent Document 3).

  Regarding the charge generation layer, as a method for improving the photomemory due to the high residual potential of the charge generation material, a method using a combination of a specific charge generation material and a specific binder resin is disclosed (Patent Literature). 4).

Regarding the charge transport layer, a method of using a charge transport material having specific parameters and providing an undercoat layer between the conductive support of the electrophotographic photoreceptor and the photosensitive layer (Patent Document 5), A method of containing an antioxidant in the transport layer (Patent Document 6) is disclosed.
JP 59-071057 A Japanese Patent Laid-Open No. 05-113671 JP 2002-278416 A JP-A-5-119493 JP 2007-293372 A Japanese Patent Laid-Open No. 1-200261

  The most effective means for preventing photo memory is to prevent unnecessary irradiation of the electrophotographic photosensitive member itself which causes photo memory. Therefore, the method of attaching a shutter to the process cartridge described in Patent Document 3 is effective. However, there are cases where it is difficult to attach a shutter to the process cartridge when the process cartridge is not used, or for other reasons due to the structure. Therefore, it is required to suppress the photo memory as the electrophotographic photosensitive member itself.

  When the present inventors are studying an electrophotographic photoreceptor, the following phenomenon occurs when a charge transport material having low solubility in a solvent used for a polycarbonate resin and a charge transport layer coating solution is used for the charge transport layer. I found.

  When an electrophotographic photosensitive member is produced, a photo memory is likely to occur when the time from immediately after application of the charge transport layer coating solution to the drying step by heating is longer than a certain time.

  Formation of a film by coating can be considered by dividing it into the following two processes. It is a coating process and a volatilization process of the coating solvent from the coated film.

  When the charge transport layer is formed by coating the charge transport layer coating liquid, it is preferable that the charge transport layer coating liquid has a uniform liquid composition and liquid concentration by stirring or the like. When the present inventors examined, the coating liquid composition and the coating liquid concentration at the time of coating were in a uniform state, and immediately after coating, the liquid composition and the liquid concentration in the coating film were sufficiently uniform. Conceivable.

  In a state where the applied film contains a large amount of solvent, molecular migration within the film can occur sufficiently. Thereafter, as the solvent gradually evaporates, the molecular movement in the film is gradually restricted. Then, after the solvent is sufficiently volatilized, the molecular movement in the film hardly occurs.

  In the study by the present inventors, as described above, the time from the application of the charge transport layer to the drying process by heating of the charge transport layer is likely to cause photo memory in the produced electrophotographic photosensitive member. There was a difference. This is considered to indicate that the length of time during which molecules can move in the applied film has an effect on the likelihood of photomemory in the produced electrophotographic photosensitive member.

  In the study by the present inventors, a material having low solubility in the solvent used for the charge transport layer coating solution was used as the charge transport material. Such a material is considered to be a material that easily aggregates and precipitates when the solvent evaporates from the applied film and the concentration of the charge transport material in the applied film increases. When the time required for the solvent to fully evaporate is compared with the time required for the charge transport material to agglomerate or deposit in the applied film, if the former is short, photo memory is unlikely to occur, and the latter is short Is presumed to be prone to photo memory.

  As a cause of the photo memory in the study by the present inventors, when the charge transport material aggregates or precipitates in the coated film, the so-called charge trap site in which the aggregated or deposited charge transport material hinders charge transport. Presumed to work as.

  As described above, in the case of using a charge transport material having low solubility in the solvent used for the polycarbonate resin and the charge transport layer coating solution, in order to obtain an electrophotographic photosensitive member that is unlikely to cause photo memory, immediately after coating the charge transport layer. The time from the drying process to the drying process may be shortened.

  However, from the viewpoint of productivity, it is strongly required to obtain an electrophotographic photosensitive member that is less likely to cause photo memory even when the time from the application of the charge transport layer to the drying step becomes longer.

  An object of the present invention is to produce a multilayer electrophotographic photosensitive member that stably suppresses the generation of photomemory even when the time from the application of the charge transport layer to the drying step of the charge transport layer is longer than a certain time. Is to provide a method.

  The present inventors use a charge transport material having a low solubility in the solvent used for the charge transport layer coating solution for the charge transport layer and a binder resin in which the polycarbonate resin is present in the charge transport layer as a binder resin. Using 95% by mass or more of the entire resin, under the condition that the time from the completion of the application of the charge transport layer to the time when the solvent content in the applied charge transport layer is 10% or less of the application is 5 minutes or more As a result of intensive studies on the phenomenon in which the photoconductor is prone to generate memory when irradiated with light, the generation of optical memory is suppressed by adding a small amount of polyarylate resin to the charge transport layer coating solution. The present inventors have found that the manufactured photoreceptor can be produced, and have achieved the present invention.

  That is, the present invention provides a method for producing a laminated electrophotographic photoreceptor having a charge generation layer on a conductive support and a charge transport layer on the charge generation layer. A step of preparing a charge transport layer coating solution by dissolving in a solvent containing monochlorobenzene, a step of dip coating the conductive support having the charge generation layer in the charge transport layer coating solution, and a step of dip coating And drying the conductive support coated with the charge transport layer coating solution in an oven, wherein the charge transport material has a solubility in a solvent containing monochlorobenzene at 25 ° C. of 50 mg / g. The charge transport material having a concentration of 300 mg / g or less is contained in an amount of 10% by mass to 100% by mass with respect to the entire charge transport material present in the charge transport layer, and the charge transport layer coating solution is applied. The solvent content in the charge transport layer is 10% or more and less than 100% at the completion of coating after 5 minutes of coating at room temperature, and the binder resin is the binder resin present in the charge transport layer. It is characterized by containing polycarbonate resin in an amount of 95 to 99.9% by mass and polyarylate resin in an amount of 0.1 to 5% by mass with respect to the whole.

  In the present invention, a charge transport material having low solubility in the solvent used for the charge transport layer coating solution is used for the charge transport layer, and the polycarbonate resin is 95% by mass to 99.9% by mass and the polyarylate resin is 0% for the binder resin. .1 mass% or more and 5 mass% or less are used. Thereby, even when the time from the application of the charge transport layer coating solution to the drying process of the charge transport layer is longer than a certain time, the production of a multilayer electrophotographic photosensitive member that stably suppresses the generation of photo memory A method can be provided.

  Hereinafter, the present invention will be described in more detail.

  As described above, the method for producing a multilayer electrophotographic photoreceptor of the present invention relates to a method for producing a multilayer electrophotographic photoreceptor having at least a conductive support, a charge generation layer, and a charge transport layer. In this charge transport layer, a charge transport material having a solubility at 25 ° C. in a solvent used for the charge transport layer coating solution of 50 mg / g or more and 300 mg / g or less is 10 mass relative to the entire charge transport material present in the charge transport layer. % To 100% by mass. In addition, the solvent content in the applied charge transport layer is 10% or more and less than 100% at the completion of application after 5 minutes of completion of application at room temperature. In the charge transport layer, the polycarbonate resin is present in an amount of 95% by mass or more and 99.9% by mass or less of the entire binder resin present in the charge transport layer. On the other hand, the present invention is a method for producing a laminated electrophotographic photosensitive member, characterized in that the polyarylate resin is present in an amount of 0.1% by mass or more and 5% by mass or less based on the entire binder resin present in the charge transport layer.

  First, a method for producing a multilayer electrophotographic photoreceptor according to the present invention will be described. In the present invention, the multilayer electrophotographic photoreceptor is produced by laminating at least a charge generation layer and a charge transport layer on a conductive support. In the present invention, each layer of the multilayer electrophotographic photoreceptor can be formed by a known method, but at least the charge transport layer is formed by a coating step of coating a coating solution. For the coating step, for example, a coating method such as a dip coating method, a spray coating method, or a ring coating method can be used. From the viewpoint of productivity, it is preferable to use a dip coating method as a method of forming each layer on the conductive support, not limited to the charge transport layer.

  Next, the structure of the electrophotographic photosensitive member produced according to the present invention will be described. The electrophotographic photosensitive member produced according to the present invention has a conductive support and an organic photosensitive layer (hereinafter also simply referred to as “photosensitive layer”) provided on the support. The present invention can be widely used for the production of a cylindrical electrophotographic photosensitive member having a photosensitive layer formed on a cylindrical support, but is also applicable to the production of a belt-shaped or sheet-shaped electrophotographic photosensitive member. is there.

  The photosensitive layer of the electrophotographic photosensitive member produced according to the present invention is a laminated type (functional separation type) photosensitive layer separated into a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. The photosensitive layer may be a normal layer type photosensitive layer laminated in the order of the charge generation layer and the charge transport layer from the support side, or a reverse layer type photosensitive layer laminated in the order of the charge transport layer and the charge generation layer from the support side. Also good. Further, the charge generation layer may have a laminated structure, and the charge transport layer may have a laminated structure. Furthermore, it is possible to provide a protective layer on the photosensitive layer for the purpose of improving the durability performance.

  As the conductive support, for example, a metal support such as aluminum, aluminum alloy, or stainless steel can be used. In the case of aluminum or aluminum alloy, ED tube, EI tube, and these are cut, electrolytic composite polishing (electrolysis with electrode having electrolytic action and polishing with grinding stone having polishing action), wet or dry honing treatment Can also be used. Moreover, the said metal support body and resin support body which have the layer by which the film was formed by vacuum deposition of aluminum, aluminum alloy, or indium tin oxide (ITO) can also be used. Examples of the resin that can be used for the resin support include polyethylene terephthalate, polybutylene terephthalate, phenol resin, polypropylene, and polystyrene resin. In addition, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, or silver particles are impregnated in a resin or paper, or a plastic having a conductive binder resin can also be used.

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

When the volume resistivity of the support is a layer provided for imparting conductivity to the surface of the support, the volume resistivity of the layer is preferably 1 × 10 ¹⁰ Ω · cm or less, In particular, it is more preferably 1 × 10 ⁶ Ω · cm or less.

  Between the support and an intermediate layer or photosensitive layer (charge generation layer, charge transport layer) described later, there is a conductive layer for the purpose of preventing interference fringes due to scattering of laser light and covering scratches on the support. It may be provided. This is a layer formed by applying a coating liquid in which conductive powder is dispersed in an appropriate binder resin.

  Examples of such conductive powder include the following. Carbon black, acetylene black; metal powder such as aluminum, nickel, iron, nichrome, copper, zinc or silver; metal oxide powder such as conductive tin oxide or ITO.

  Moreover, as binder resin used simultaneously, the following thermoplastic resins, thermosetting resins, or photocurable resin resins are mentioned. Polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, and polyvinylidene chloride. Further, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, and polyvinyl toluene may be used. Furthermore, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, or alkyd resin can also be used.

  The conductive layer can be formed by dispersing or dissolving the conductive powder and the binder resin in a solvent and applying the solution. Usable solvents are ether solvents such as tetrahydrofuran or ethylene glycol dimethyl ether; alcohol solvents such as methanol; ketone solvents such as methyl ethyl ketone; aromatic hydrocarbon solvents such as toluene.

  The average thickness of the conductive layer is 0.2 μm or more and preferably 40 μm or less, more preferably 1 μm or more and 35 μm or less, and further 5 μm or more and 35 μm or less. It is even more preferable.

  The surface of a conductive layer in which a conductive pigment or a resistance adjusting pigment is dispersed tends to be roughened.

  An intermediate layer having a barrier function or an adhesive function may be provided between the support or the conductive layer and the photosensitive layer (charge generation layer, charge transport layer). The intermediate layer is formed, for example, for improving adhesion of the photosensitive layer, improving coating properties, improving charge injection from the support, and protecting the photosensitive layer from electrical breakdown.

  The intermediate layer can be formed by applying a curable resin and then curing to form a resin layer, or applying an intermediate layer coating solution containing a binder resin on the conductive layer and drying.

  Examples of the binder resin for the intermediate layer include the following. Water-soluble resins such as polyvinyl alcohol, polyvinyl methyl ether, polyacrylic acids, methyl cellulose, ethyl cellulose, polyglutamic acid or casein; polyamide resins, polyimide resins, polyamideimide resins and polyamic acid resins. Moreover, a melamine resin, an epoxy resin, a polyurethane resin, or a polyglutamic acid ester resin may be used.

  In order to effectively develop the electrical barrier property, the binder resin of the intermediate layer is preferably a thermoplastic resin from the viewpoints of coatability, adhesion, solvent resistance and resistance. Specifically, a thermoplastic polyamide resin is preferable. The polyamide resin is preferably a low crystalline or non-crystalline copolymer nylon that can be applied in a solution state. The average film thickness of the intermediate layer is preferably 0.05 μm or more and 7 μm or less, more preferably 0.1 μm or more and 2 μm or less.

  Also, in order to prevent the flow of electric charges (carriers) in the intermediate layer, the semiconductive particles are dispersed in the intermediate layer, or an electron transport material (electron-accepting material such as an acceptor) is contained. You may let them.

  Next, the photosensitive layer of the electrophotographic photoreceptor produced according to the present invention will be described.

  Examples of the charge generating material used for the photosensitive layer include the following. An azo pigment such as monoazo, disazo or trisazo; a phthalocyanine pigment such as metal phthalocyanine or non-metal phthalocyanine; an indigo pigment such as indigo or thioindigo; and a perylene pigment such as perylene anhydride or perylene imide. Also, polycyclic quinone pigments such as anthraquinone or pyrenequinone; squarylium dyes, pyrylium salts or thiapyrylium salts, triphenylmethane dyes; inorganic substances such as selenium, selenium-tellurium or amorphous silicon may be used. Furthermore, a quinacridone pigment, an azulenium salt pigment, a cyanine dye, a xanthene dye, a quinoneimine dye, or a styryl dye may be used. These charge generation materials may be used alone or in combination of two or more. Among these, metal phthalocyanines such as oxytitanium phthalocyanine, hydroxygallium phthalocyanine or chlorogallium phthalocyanine are particularly preferable because of their high sensitivity.

  Examples of the binder resin used for the charge generation layer include the following. Polycarbonate resin, polyester resin, polyarylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, and vinyl acetate resin. Further, phenol resin, silicone resin, polysulfone resin, styrene-butadiene copolymer resin, alkyd resin, epoxy resin, urea resin or vinyl chloride-vinyl acetate copolymer resin may be used. In particular, a butyral resin is preferred. These may be used alone or in combination as a mixture or copolymer.

  The charge generation layer can be formed by applying and drying a charge generation layer coating solution obtained by dispersing a charge generation material together with a binder resin and a solvent. The charge generation layer may be a vapor deposition film of a charge generation material. Examples of the dispersion method include a method using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, or a roll mill. The ratio between the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10 (mass ratio), and more preferably in the range of 3: 1 to 1: 1 (mass ratio).

  The solvent used for the charge generation layer coating solution is selected based on the solubility and dispersion stability of the binder resin and charge generation material used. Examples of the organic solvent include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

  The average film thickness of the charge generation layer is preferably 5 μm or less, and more preferably 0.1 to 2 μm.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, or plasticizers can be added to the charge generation layer as necessary. In order to prevent the flow of charges (carriers) in the charge generation layer from stagnation, the charge generation layer may contain an electron transport material (an electron accepting material such as an acceptor).

  Next, the charge transport layer coating solution and the formed charge transport layer in the present invention will be described.

  The charge transport layer coating solution in the present invention contains at least one kind of charge transport material, polycarbonate resin, and polyarylate resin in addition to the solvent.

  Examples of the charge transport material used for the charge transport layer in the present invention include the following. Benzidine compound, triarylamine compound, hydrazone compound, styryl compound, stilbene compound, pyrazoline compound, oxazole compound, thiazole compound or triallylmethane compound. These charge transport materials may be used alone or in combination of two or more. Of these, at least one charge transport material has a solubility at 25 ° C. in a solvent used for the charge transport layer coating solution of 50 mg / g. It is 300 mg / g or less. The charge transport material preferably has a compound represented by the following general formula (1).

(In the general formula (1), Ar ₁ , Ar ₂ , Ar ₅ and Ar ₆ represent aryl groups which do not contain nitrogen and may have a substituent, and may be the same or different. Ar ₃ and Ar ₄ represent an arylene group which may have a substituent, and may be the same or different.

  The charge transport layer in the present invention contains 95% by mass or more and 99.9% by mass or less of the total binder resin present in the charge transport layer as a binder resin, and a polyarylate resin is present in the charge transport layer. 0.1 mass% or more and 5 mass% or less of the whole binder resin to contain.

  The reason why the photomemory is suppressed by including the polyarylate resin is to prevent the charge transport material from aggregating or precipitating in the applied film to form charge trap sites as described above. It is estimated that. The reason why the polyarylate resin is particularly effective is thought to be influenced by the molecular structure of polyarylate and polycarbonate, but details are not clear at this time.

  The effect of suppressing the photomemory can be obtained by making the polyarylate resin at least 0.1% by mass or more of the entire binder resin present in the charge transport layer. Further, the effect of suppressing the photomemory can be sufficiently achieved if the polyarylate resin is contained in an amount of 5% by mass or less of the entire binder resin present in the charge transport layer. The polyarylate resin is used in an amount of 0.5% by mass or more in order to exhibit the effect of suppressing the photomemory with almost no change from the characteristics when the polycarbonate resin is used alone as the binder resin for the charge transport layer. More preferably, the content is less than or equal to mass%.

  The ratio between the charge transport material and the binder resin is preferably in the range of 2: 1 to 1: 2 (mass ratio).

  In addition, for example, an antioxidant, an ultraviolet absorber, or a lubricant can be added to the charge transport layer as necessary. The following are mentioned as a solvent used for a charge transport layer coating liquid. Ketone solvents such as acetone or methyl ethyl ketone; ester solvents such as methyl acetate or ethyl acetate; ether solvents such as tetrahydrofuran, dioxolane, dimethoxymethane or dimethoxyethane. An aromatic hydrocarbon solvent such as toluene, xylene or chlorobenzene may also be used. These solvents may be used alone or in combination of two or more. Among these solvents, it is preferable to use an ether solvent, an aromatic hydrocarbon solvent, or a solvent obtained by mixing these solvents from the viewpoints of resin solubility and film formability.

  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 charge transport layer is applied using a coating method such as a dip coating method. In the present invention, 5 minutes after the charge transport layer coating is completed, the solvent content in the applied charge transport layer at room temperature is the applied amount. It is 10% or more and less than 100% when completed.

  The solvent content in the applied charge transport layer 5 minutes after completion of the charge transport layer coating was measured by the following method.

  The sample weight before application of the charge transport layer is A, the sample weight 5 minutes after completion of the application of the charge transport layer is B, and the weight after the sample after application of the charge transport layer is dried in an oven at 120 ° C. for 30 minutes is C. A, B, and C were measured, respectively. For the measurement, a known weight measuring device such as an electronic balance can be used. Further, D was the ratio of the solid content contained in the charge transport layer coating liquid immediately after completion of the charge transport layer coating.

  The ratio of the solid content of the charge transport layer coating solution can be determined using a known method such as a heat-dry weight method with respect to the coating solution immediately after the completion of coating.

  First, the solid content weight E of the applied charge transport layer can be found by calculating C-A. Next, by calculating A + (E / D), the sample weight F in a state where the solvent in the applied charge transport layer is not volatilized after the charge transport layer is applied can be found. Further, by calculating (F−B) / (F−C), the solvent content in the applied charge transport layer 5 minutes after the completion of the application of the charge transport layer can be calculated. The ratio with respect to solvent content can be calculated | required.

  In the practice of the present invention, it is a principle that the drying is performed for 30 minutes in an oven heated to 120 ° C. after 5 minutes from the completion of coating.

  The average film thickness of the charge transport layer formed through the coating process and the drying process is preferably 5 to 50 μm, more preferably 8 to 35 μm.

  Various additives can be added to each layer of the electrophotographic photoreceptor produced according to the present invention. Examples of the additive include an antioxidant, a deterioration inhibitor for ultraviolet absorbers, and a lubricant for fluorine atom-containing resin particles.

  Next, a process cartridge and an electrophotographic apparatus having an electrophotographic photosensitive member manufactured according to the present invention will be described. FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having an electrophotographic photosensitive member according to the present invention.

  In FIG. 1, reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is rotationally driven in a direction of an arrow about a shaft 2 at a predetermined peripheral speed.

  The surface of the electrophotographic photosensitive member 1 that is rotationally driven is uniformly charged to a predetermined positive or negative potential by a charging unit (primary charging unit: for example, a charging roller) 3. Next, exposure light (image exposure light) 4 output from exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the surface of the electrophotographic photosensitive member 1.

  The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in the developer of the developing means 5 to become a toner image. Next, the toner image formed and supported on the surface of the electrophotographic photoreceptor 1 is sequentially transferred onto a transfer material (for example, paper) 11. The transfer material 11 is electrophotographic photosensitive between a transfer material supply unit (not shown) and the electrophotographic photosensitive member 1 and the transfer unit 6 (contact portion) by a transfer bias from a transfer unit (for example, a transfer roller) 6. It is fed in synchronization with the rotation of the body 1.

  The transfer material 11 that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member 1 and introduced into the fixing means 7 to receive image fixing, thereby printing out as an image formed product (print, copy) outside the apparatus. Is done.

  The surface of the electrophotographic photoreceptor 1 after the transfer of the toner image is cleaned by receiving a developer (toner) remaining after transfer by a cleaning means (for example, a cleaning blade) 8. Further, the surface of the electrophotographic photoreceptor 1 is subjected to charge removal processing by pre-exposure light (not shown) from pre-exposure means (not shown), and then repeatedly used for image formation. As shown in FIG. 1, when the charging unit 3 is a contact charging unit using, for example, a charging roller, pre-exposure is not always necessary.

  Among the components of the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5 and the cleaning unit 8, a plurality of components may be housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. In FIG. 1, the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5 and the cleaning unit 8 are integrally supported to form a cartridge, and the electrophotographic apparatus is used with a guide unit 9 such as a rail of the electrophotographic apparatus main body. The process cartridge 10 is detachable from the apparatus main body.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. In the examples, “part” means “part by mass”.

Example 1
<Production of electrophotographic photoreceptor>
An aluminum cylinder having a diameter of 24 mm and a length of 257 mm obtained by hot extrusion in an environment of 23 ° C. and 60% RH was used as a support (cylindrical support). This aluminum cylinder is an aluminum alloy ED pipe (manufactured by Showa Aluminum Co., Ltd.) specified as a material symbol A3003 in JIS.

Next, a solution comprising the following components was dispersed with a ball mill for about 20 hours to prepare a conductive layer coating solution.
Powder made of barium sulfate particles having a tin oxide coating layer (trade name: Pastoran PC1, manufactured by Mitsui Mining & Smelting Co., Ltd.) 60 parts Titanium oxide (trade name: TITANIX JR, manufactured by Teika Co., Ltd.) 15 parts phenol resin (Product name: Priorofen J-325, manufactured by Dainippon Ink & Chemicals, Inc., resin solid content 60%) 43 parts silicone oil (Product name: SH28PA, manufactured by Toray Dow Corning Co., Ltd.) 0.015 parts Silicone Resin particles (trade name: Tospearl 120, manufactured by Momentive Performance Materials Japan (G)) 3.6 parts 1-methoxy-2-propanol 50 parts methanol 50 parts

  The conductive layer coating solution prepared by the above method is applied on the support by a dipping method, and cured by heating in an oven heated to 140 ° C. for 1 hour, so that the position at 125 mm from the upper end of the support is obtained. A conductive layer having an average film thickness of 15 μm was formed.

Next, a coating solution for an intermediate layer in which the following components are dissolved in a mixed solution of 400 parts of methanol / 200 parts of n-butanol is dip-coated on the conductive layer. Then, the intermediate layer with an average film thickness of 0.60 μm at a position of 125 mm from the upper end of the support was formed by heating and drying in an oven heated to 100 ° C. for 30 minutes.
Copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) 10 parts N-methoxymethylated 6 nylon resin (trade name: Toresin EF-30T, manufactured by Nagase ChemteX Corporation) 30 parts Were dispersed for 4 hours in a sand mill using 1 mm diameter glass beads, and 700 parts of ethyl acetate was added to prepare a coating solution for a charge generation layer.
Hydroxygallium phthalocyanine (in CuKα characteristic X-ray diffraction, 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 °, 28.3 ° (Bragg angle (2θ ± 0.2 ° )) Strong diffraction peak) 20 parts Calixarene compound represented by the following structural formula (2) 0.2 part polyvinyl butyral (trade name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 10 parts cyclohexanone 600 Part

  The charge generation layer coating solution is applied on the intermediate layer by a dip coating method, and is heated and dried in an oven heated to 80 ° C. for 15 minutes, whereby the average film thickness at a position of 125 mm from the upper end of the support is 0.00. A 17 μm charge generation layer was formed.

Next, the following components were dissolved in a mixed solvent of 600 parts of monochlorobenzene and 200 parts of dimethoxymethane to prepare a charge transport layer coating solution. Using this, the charge transport layer is dip-coated on the charge generation layer, and after 5 minutes from the completion of the coating, by heating and drying in an oven heated to 120 ° C. for 30 minutes, 125 mm from the upper end of the support. A charge transport layer having an average film thickness of 20 μm was formed. Five minutes after the charge transport layer application was completed, the solvent content in the applied charge transport layer was 40% of the completion of the application.
80 parts of charge transport material (hole transport material) represented by the following structural formula (3) Polycarbonate resin composed of repeating units represented by the following structural formula (4) (Iupilon Z-400, Mitsubishi Engineering Plastics Co., Ltd.) Manufactured) [viscosity average molecular weight (Mv) 40,000] 99 parts 1 part of polyarylate resin represented by the following structural formula (5)

  Table 1 shows the solubility of the charge transport material represented by the structural formula (3) at 25 ° C. with respect to the solvent used in the charge transport layer coating solution.

<Characteristic evaluation of electrophotographic photoreceptor>
The optical memory test of the produced electrophotographic photosensitive member was performed as follows.

First, a part of the produced electrophotographic photoreceptor was irradiated with white light adjusted so that the amount of light on the photoreceptor surface was 2000 Lux for 60 minutes, and then stored in a dark place for 24 hours. Next, the photoconductor was mounted on a potential measuring jig for a laser beam printer (trade name: Laserjet 3700, manufactured by Hewlett-Packard Company). Next, it was mounted on the laser beam printer modified so that the dark portion potential was −500 V and the exposure light amount was 0.28 μJ / cm ² , and the bright portion potential difference between the white light exposed portion and the non-exposed portion was measured. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 1, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Example 2)
The solvent used for the charge transport layer coating solution was prepared and evaluated in the same manner as in Example 1 except that only 800 parts of monochlorobenzene was used. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 50% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 2, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Example 3)
It was produced and evaluated in the same manner as in Example 1 except that the solvent used for the charge transport layer coating solution was changed to a mixed solvent of 400 parts of monochlorobenzene and 400 parts of dimethoxymethane. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 30% at the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 3, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

Example 4
The charge transport material was changed to 60 parts of a charge transport material (hole transport material) represented by the structural formula (3) and 20 parts of a charge transport material (hole transport material) represented by the following structural formula (6). It produced and evaluated similarly to Example 1. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 4, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Example 5)
Implementation was carried out except that the charge transport material was changed to 40 parts of the charge transport material (hole transport material) represented by the structural formula (3) and 40 parts of the charge transport material (hole transport material) represented by the structural formula (6). It produced and evaluated like Example 1. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 5, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Example 6)
Implemented except that the charge transport material was changed to 8 parts of charge transport material (hole transport material) represented by structural formula (3) and 72 parts of charge transport material (hole transport material) represented by structural formula (6). It produced and evaluated like Example 1. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 6, the bright part potential difference between the white light exposed part and the non-exposed part is 5 V or less, and the occurrence of photo memory is suppressed.

(Example 7)
Example except that the resin was changed to 97 parts of the binder resin represented by the structural formula (4), 1 part of the binder resin represented by the structural formula (5) and 2 parts of the resin represented by the following structural formula (7). 1 was prepared and evaluated. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 7, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Example 8)
It was produced and evaluated in the same manner as in Example 1 except that the time from the completion of the application of the charge transport layer to the heat drying in the oven was changed to 15 minutes. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 8, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

Example 9
The resin was prepared and evaluated in the same manner as in Example 1 except that the resin was changed to 98 parts of the binder resin represented by the structural formula (4) and 2 parts of the binder resin represented by the structural formula (5). At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 9, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Example 10)
The resin was prepared and evaluated in the same manner as in Example 1 except that the resin was changed to 99.5 parts of the binder resin represented by the structural formula (4) and 0.5 part of the binder resin represented by the structural formula (5). . At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 10, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Example 11)
The resin was prepared and evaluated in the same manner as in Example 1 except that the resin was changed to 99.9 parts of the binder resin represented by the structural formula (4) and 0.1 part of the binder resin represented by the structural formula (5). . At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 11, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V, and the suppression of the occurrence of photomemory is not as high as in Examples 1-10.

Example 12
Example except that the polycarbonate resin composed of the repeating unit represented by the structural formula (4) was changed to Iupilon Z-200 (manufactured by Mitsubishi Engineering Plastics) [viscosity average molecular weight (Mv) 20,000] 1 was prepared and evaluated. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 12, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

  Therefore, even if the polycarbonate resin has a low molecular weight, the polycarbonate resin is present in an amount of 95% by mass or more and 99.9% by mass or less of the entire binder resin present in the charge transport layer, and the remainder of the resin is a polyarylate resin. The occurrence of photo memory can be suppressed.

(Example 13)
The resin was prepared and evaluated in the same manner as in Example 1 except that the resin was changed to 95 parts of the binder resin represented by the structural formula (4) and 5 parts of the binder resin represented by the structural formula (5). At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Example 13, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

  In Table 2, it can be seen that in Example 13, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

  Therefore, if the polycarbonate resin is present in an amount of 95% by mass or more and 99.9% by mass or less of the entire binder resin present in the charge transport layer and the remainder of the resin is a polyarylate resin, the occurrence of photo memory can be suppressed.

(Comparative Example 1)
The resin was prepared and evaluated in the same manner as in Example 1 except that only 100 parts of the binder resin represented by the structural formula (4) was used. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, in Comparative Example 1, the bright portion potential difference between the white light exposed portion and the non-exposed portion reaches 35 V, and it cannot be said that the occurrence of photo memory is suppressed.

(Comparative Example 2)
The solvent used for the charge transport layer coating solution was prepared and evaluated in the same manner as Comparative Example 1 except that only 800 parts of monochlorobenzene was used. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 50% of the completion of the application. The results are shown in Table 2.

  In Table 2, in Comparative Example 2, it cannot be said that the bright portion potential difference between the white light exposed portion and the non-exposed portion reaches 30 V, and the occurrence of photo memory is not suppressed.

(Comparative Example 3)
Comparison except that the charge transport material was changed to 40 parts of charge transport material (hole transport material) represented by structural formula (3) and 40 parts of charge transport material (hole transport material) represented by structural formula (6) It produced and evaluated like Example 1. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, in Comparative Example 3, the bright portion potential difference between the white light exposed portion and the non-exposed portion reaches 15 V, and it cannot be said that the occurrence of photo memory is suppressed.

(Comparative Example 4)
Comparison except that the charge transport material was changed to 8 parts of charge transport material (hole transport material) represented by structural formula (3) and 72 parts of charge transport material (hole transport material) represented by structural formula (6) It produced and evaluated like Example 1. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, in Comparative Example 4, the bright portion potential difference between the white light exposed portion and the non-exposed portion reaches 10 V, and it cannot be said that the occurrence of photo memory is suppressed.

(Reference Example 1)
The charge transport material was prepared and evaluated in the same manner as in Comparative Example 1 except that the charge transport material was changed to only 80 parts of the charge transport material (hole transport material) represented by the structural formula (6). At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Reference Example 1, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Reference Example 2)
It was produced and evaluated in the same manner as in Comparative Example 1 except that the time from the completion of the application of the charge transport layer to the heat drying in the oven was changed to 1 minute. The sample weight 5 minutes after completion of charge transport layer application was measured by removing the sample from the oven 5 minutes after completion of charge transport layer application. Five minutes after the charge transport layer application was completed, the solvent content in the applied charge transport layer was 5% or less when the application was completed. In the measurement of the photo memory, a sample that was not taken out of the oven during the oven drying for 30 minutes was used. The results are shown in Table 2.

  In Table 2, it can be seen that in Reference Example 2, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

(Reference Example 3)
Comparison except that the charge transport material was changed to 4 parts of charge transport material (hole transport material) represented by structural formula (3) and 76 parts of charge transport material (hole transport material) represented by structural formula (6) It produced and evaluated like Example 1. At the time of production, 5 minutes after the completion of the application of the charge transport layer, the solvent content in the applied charge transport layer was 40% of the completion of the application. The results are shown in Table 2.

  In Table 2, it can be seen that in Reference Example 3, the bright portion potential difference between the white light exposed portion and the non-exposed portion is 5 V or less, and the occurrence of photo memory is suppressed.

1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having an electrophotographic photosensitive member according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Fixing means 8 Cleaning means 9 Guide means 10 Process cartridge 11 Transfer material

Claims (5)

In a method for producing a laminated electrophotographic photoreceptor having a charge generation layer on a conductive support and a charge transport layer on the charge generation layer,
Dissolving a charge transport material and a binder resin in a solvent containing monochlorobenzene to prepare a charge transport layer coating solution;
Dip-coating the conductive support having the charge generation layer in the charge transport layer coating solution;
Heating and drying the conductive support coated with the charge transport layer coating solution in the dip coating step in an oven;
With
The charge transport material is 10 masses of the charge transport material having a solubility in a solvent containing monochlorobenzene at 25 ° C. of 50 mg / g or more and 300 mg / g or less with respect to the entire charge transport material present in the charge transport layer. % To 100% by mass or less,
The solvent content in the charge transport layer coated with the charge transport layer coating solution is 10% or more and less than 100% at the completion of coating after 5 minutes of coating at room temperature,
The binder resin is 95% by mass or more and 99.9% by mass or less of polycarbonate resin, 0.1% by mass or more and 5% by mass or less of polyarylate resin with respect to the entire binder resin present in the charge transport layer. A method for producing a laminated electrophotographic photosensitive member, comprising:   2. The method for producing a laminated electrophotographic photoreceptor according to claim 1, wherein the solvent containing monochlorobenzene is a mixed solvent of monochlorobenzene and dimethoxymethane or monochlorobenzene.   3. The multilayer electrophotographic image according to claim 1, wherein the polyarylate resin is present in an amount of 0.5% by mass or more and 2% by mass or less with respect to the entire binder resin present in the charge transport layer. Photoconductor manufacturing method.   4. The method for producing a laminated electrophotographic photosensitive member according to claim 1, wherein a ratio of the charge transport material and the binder resin is 2: 1 to 1: 2 by mass ratio. . 5. The method for producing a laminated electrophotographic photosensitive member according to claim 1, wherein the charge transporting material includes a compound represented by the following general formula (1).

(In the general formula (1), Ar ₁ , Ar ₂ , Ar ₅ and Ar ₆ represent aryl groups which do not contain nitrogen and may have a substituent, and may be the same or different. Ar ₃ and Ar ₄ represent an arylene group which may have a substituent, and may be the same or different.